text:
If a woman was fertilized with her own DNA, would it be her clone?
Several questions:

1) Can human DNA fertilize an egg, without having been naturally packaged in a sperm cell?
2) If a female had her ovum fertilized with her own DNA, would the fetus be her clone?
3) If this technology of fertilizing ovum from arbitrary samples of human DNA were effective, would males be unnecessary for reproduction of the human species? (No political implications, just a thought experiment.)

Thank you for your insight!

You might be interested in this.

1)
In principle yes, you could in theory use micro injection to inject haploid DNA into the egg. I don't think this has been used in practice though. However Dolly the sheep was created by exchanging haploid nucleus of a sheep egg with a diploid nucleus from a mammary gland cell.
2)
Not necessarily, DNA is packaged into chromosomes and diploid cells have two copies of the same chromosome (with the exception being the sex chromosomes MALE:XY FEMALE:XX). Remember that gametes are haploid (single copy of each chromosome) and that homologous recombination occurs during gamete formation, therefore the chance of obtaining two identical sets of haploid DNA that also match the females is extremely low, unless all chromosome pairs are completely identical.
3)
In principle yes. I could imagine that DNA extraction from eggs could be used for artificial fertilization and the result of that would be a race of all females.

Thank you especially for clarifying the clone issue (2). Appreciated

No it is not possible. For fertilization only DNA is not required. Sperm is necessary for fertilization because it provides centriole also for cleavage of zygote as ovum does not contain centriole.

Again, see my comment about your answer style.


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Are lanternfish real?
Is there a real lantern fish existing in the world? If yes, kindly share a picture if one exists. I searched online for images, but most of them seem to be fake. The pictures I have seen on the internet were of a fish with a hanging lantern over its head. Are these possibly real pictures?

Do you have a picture? And yes, these fish are real.

Fish you are referring to by description "fish with a hanging lantern over its head", are not lanternfish. Fish with "lantern" bait above head are members of group of fish named anglerfish (Lophiiformes).
You can find more information about them here: https://en.wikipedia.org/wiki/Anglerfish
Lanternfishes or myctophids are smaller fish that use bioluminecence for communication during mating season.
https://en.wikipedia.org/wiki/Lanternfish

Any added image would be appreciated :)

As Domagoj mentions in his answer, it sounds like you are actually referring to an anglerfish (family Lophiiformes) and not a lanternfish (family Myctophidae).
Assuming this is the case, you can see video footage of the Black Seadevil (genus Melanocetus), a deep-sea anglerfish here.
I've copied some footage from the video (from MBARI*) below as gifs:

The Aquarium video provides the following description:

Deep-sea anglerfish are strange and elusive creatures that are very rarely observed in their natural habitat. Fewer than half a dozen have ever been captured on film or video by deep diving research vehicles. This little angler, about 9 cm long, is named Melanocetus. It is also known as the Black Seadevil and it lives in the deep dark waters of the Monterey Canyon. MBARI's ROV Doc Ricketts observed this anglerfish for the first time at 600 meters on a midwater research expedition in November 2014. We believe that this is the first video footage ever made of this species alive and at depth.

You can see footage of another species of anglerfish here.
*MBARI = Monterey Bay Aquarium Research Institute.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

sort: votes


text:
Why aren't drugs tested on sick patients proactively?
I read an article about a new drug which may stop neurodegenerative activity in the brain and this triggered a question I had for some time already.
Why such novel drugs are not tested on seriously/terminally ill patients, to check whether they are not dangerous, and maybe useful?
I completely understand the need for double - blind trials which can assess that the drug works or not. This requires a lot of tests beforehand to make sure that the drug is reasonably safe for humans.
On the other hand I am sure that seriously or terminally ill patients would take the risk to, maybe, have a chance with the new drug, with the risk of complications (all in reasonable boundaries). I know I would.
Beside some indication that the drug works or not (again, I understand the  implications of a lack of double-blind trial but if the result is 100% success or failure, it is at least one data point) it could be an indication of its lack of safety. If all patients develop an unrelated organ failure (as it was the case in the article I linked), it would help research which otherwise relies on similarities between animals and humans.
Is it just an ethical concern or are there scientific reasons not to use these opportunities?

For one reason: It is extremely unethical. Additionally, such patients are not really the optimal candidates, as they have underlying diseases and treatments, which might affect the outcome of the trial without anybody noticing. Then you want to have a homogenous treatment group to detect negative effects of your treatment. There are some examples of new drugs being tested in patients, but these are then the last hope to get some treatment.

Sometimes they are, as mentioned by Chris. But keep in mind, please, that without proper testing (and even sometimes with), drugs may shorten a lifespan. There is an ethical and scientific responsibility to avoid administering drugs willy-nilly, just because someone is close to death. With trazadone, there should be ample evidence out there already, visible through the retrospectoscope. Many drugs have found a new use through this method, including minoxidil and amantadine.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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What does chrUn mean in the output from a Bowtie run on human sequences?
After having performed an alignment using bowtie2 and GRCh38 as a reference sequence, I got inusual matches on chrUn.
Here a small part of the SAM file:
@SQ     SN:chr22   LN:50818468
@SQ     SN:chrX    LN:156040895
@SQ     SN:chrY    LN:57227415
@SQ     SN:chrM    LN:16569
@SQ     SN:chrUn_KI270424v1     LN:2140

All the other chr values are clear to me (M indicates the Mitochondrial DNA, while 22, Y and X are just the usual chromosomes number/name) but I couldn't figure out what chrUn stands for and what about that code after the _?

Usually "Unknown". Sequences that have not been assigned to one of the chromosomes. I think this is from the Human genome, which has multiple sequences not assigned to a chromosome, so they have identifiers (the KI...)

@skymningen Thank you. If you add a reference and post it as an answer I will accept it.

There is no reference for this, other than experience, sorry.

I presume chrUn_KI270424v1 refers to a scaffold or sequence that has not yet been assigned to a chromosome. The designation after the Un (unknown or unassigned?) may refer to a particular single sequence or a scaffold. You will be able to determin this by examining the reference sequence and its documentation.
(My assumption is based on the sort of thing one finds in the various versions of Drosophila reference genomes, with which I am familiar. So I can’t help you with the specifics of the human genome.)

It is for unassigned sequences. See this reference from the UCSC Genome Browser FAQ: https://genome.ucsc.edu/FAQ/FAQdownloads.html#download11


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Why are there two mature sequences of microRNAs in miRBase entries?
In the miRBase database entries generally show a stem loop sequence and two mature sequences. For example the entry for hsa-mir-15a gives three sequences: (1) the Stem-loop sequence hsa-mir-15a, (2) Mature sequence hsa-miR-15a-5p, and (3) Mature sequence hsa-miR-15a-3p.
What is the difference between the two mature sequences? Does the stem loop structure divide into two different miRNA species?

I am not sure whether it is made clear in the Wikipedia article on microRNAs, but, yes, there are two possible mature mir species that can be generated from the stem-loop precursor — one from each side of the stem — although most often one greatly predominates.
The diagram in Wikipedia shows the generation of a single miRNA:

However, the entry mentioned in the question (hsa-mir-15a) shows that although the 5′-stem component (UAGCA…) is most abundant in this case, there is a small amount of the 3′-stem component (CAGGC…).

In Drosophila melanogaster a single stem component (more often from the 3′-stem, but also from the 3′-stem) most frequently predominates, but I have personally found microRNAs in which both components occur in similar amounts (unpublished).


text:
What is meant by “genes at the trunk of the evolutionary tree”?
Recently I went through a paper about hepatocellular carcinoma in which they talked about trunk genes (p. 26, second paragraph):

Branching tumor evolution complicates efforts to implement
  personalized medicine and suggests that targeted therapies might be
  directed to genes that are mutated at the trunk of the evolutionary
  tree. Transposons provide powerful tools for identifying trunk genes,
  as insertions in trunk genes are more likely to be associated with a
  higher number of sequencing reads.

I really don’t understand what are the trunk genes. Can anyone please explain them clearly.
Thank you

I've tidied up you question a little and given focus to the key concept at issue — the "genes at the trunk of the evolutionary tree".

I think the article is using a phylogenetic tree to explain the stages of how the tumor has evolved.
According to Nature.com >>

All trees have a shared 'trunk', which represents the complement of
  mutations shared by all malignant cells within the cancer.

Or simplified by Britannica.com >>

Phylogenetic tree, also called Dendrogram, a diagram showing the
  evolutionary interrelations of a group of organisms derived from a
  common ancestral form. The ancestor is in the tree “trunk”; organisms
  that have arisen from it are placed at the ends of tree “branches.”

For a visual representation, this is a phylogenetic tree for evolution of breast cancer >>

Image Source: Phylogenetic Cancer Trees

My first few readings of the sentence, I thought the article meant the ontogenetic tree -- that is, the mutation occurred early in the life of that specific individual.  From the word "evolutionary", though, I think you are right.  Still, the confusion is a warning to technical writers to use metaphors only very carefully.

@Malvolio I had the similar confusion, although upon reading the abstract the OP has provided, I am pretty sure the trunk genes they have mentioned in the context of evolutionary trees is what I have answered. Needless to say, I totally agree with you about the careful use of these terms.

@user3351523 My pleasure. Glad I could help.


text:
What is the name of this yellow flower?
India, It was growing outside.
April 2017

Center part of the flower giving me Heebie-jeebies.

'Center part of the flower giving me Heebie-jeebies'... it is a compositae (= asteraceae) member, and  anatomically not a flower-rather an entire inflorescence . The flowers at  central part is called disk-florets.

I think this is Cosmos sulphureus which is also known as yellow cosmos or sulfur cosmos. See the image (from here) as comparision:

More information can be found here and here.


text:
Can Blood Types Change?
I recently heard a radio show where two callers claimed that their blood types had changed. One caller claimed that he was born O-, but recent tests said he was A+. Another caller claimed to change from AB- to AB+. Both callers claim that they had multiple tests before and after the change.
What I noticed is that both cases claim a conversion from Rh- to Rh+, or from type O to some other type. These could potentially be explained by a person carrying a gene for Rh factor or some other blood type, but failing to express the protein. Then the gene starts expressing, changing their blood type.
Of course both stories could be false, intentionally or otherwise. This is purely anecdotal evidence, and one caller claimed that her blood type change was due to extraterrestrial interference. I couldn't find any better documented cases of blood type changes after a quick search on the internet, so I thought I'd ask here.
Are there any documented cases of a change in blood type?

This is highly unlikely. The only reason which comes to my mind would be a transfer of stem cells (aka bone marrow transplant).

@Chris And I doubt that aliens are transferring stem cells.

Embryonic bone marrow transplant, maybe...? But that wouldn't work since they'd tested blood group earlier too ;)

@another'Homosapien' I would suspect that either the first test was wrong or somebody remembered something wrong.

@chris my first idea would be: "if your blood type has changed, then your body (immune system) will very soon kill you". It surely isn't easy at all...there has to be some misunderstanding here.

Possible in leukaemia.

@another'Homosapien' not in the cases when antigen is not expressed ie. if blood group changes from AB to A or B or O , or from AorB to O.

@jm97 yeah...I meant that only in cases mentioned here :P

And how are we 100% sure that hemagglutination will not happen? I also believe that there is a very high death rate, and as a result, there will be no longer human living populations with that symptoms. But what happens if the O- type changes to A+ type, I don't know. And especially how Rh- changes to Rh+, is just a mystery. @user137 Can you provide us a link where we can see if that hypothesis is true? Please check online for that radio conversation you heard. To sum up, what happens with the antigenes? It is extremely lethal to mix the blood types...

@The_Mad_Fish This was the show, I think it was the April 13th or 14th shows, but they don't let you listen to past shows without paying, so I can't link to the exact shows. But the evidence I list is the evidence they gave, purely anecdotal. Could the antigens be expressed at such low levels that hemagglutination doesn't happen?

@user137 No antigenes dont express "mildly" or "in a soft way". Their expression (if it happens, but in our case it happens 100%) is done with an almost sure result (e.g Hemagglutination).

Blood group antigens are either sugars or proteins found attached to the red blood cell membrane. ABO blood group antigens are the most clinically important antigens because they are the most immunogenic. As red blood cell antigens are inherited traits, they are usually not altered throughout the life of an individual. There have been occasional case reports of ABO blood group antigen change in malignant conditions,ABO antigen alteration associated with acute myeloid leukemia. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5242122/
https://www.ncbi.nlm.nih.gov/pubmed/15135601 ( B to O change)
https://www.ncbi.nlm.nih.gov/pubmed/22270426 (New laboratory procedures and Rh blood type changes in a pregnant woman.)
A bone marrow transplant will replace the cells which make your blood cells with cells from the donor. Over about 3-4 months (life span of a red cell), your blood will become your donors type.


text:
Can plants produce oxygen at night (without light)?
I accidentally clicked on a "Top n X's that Y" result in google and found Top 9 Plants that gives (sic) off Oxygen at night as well (best for indoors).
In this helpful answer I've found a nice, concise description that I'm just going to reproduce here:

Photosynthesis consists of two general steps, one that requires light and one that does not. The first step occurs in the thylakoid membrane, and splits water into oxygen, hydrogen ions, and energy. The second step is the carbon fixation step, which occurs in the chloroplasts and uses energy to convert the carbon dioxide into carbohydrates.
Step 1: $\ce{2 H2O + light → 2 H+ + O2 + energy}$
Step 2: $\ce{3 CO2 + 6 H+ + energy → C3H6O3-P + 3 H2O}$

In general, the oxygen released from plants comes from water splitting which is driven (in a multi-step process) by photons. From what I remember, the oxygen molecules ($\ce{O2}$) are usually produced and released to the air within seconds, and certainly within minutes after all of the necessary photons for it have been absorbed.
So I am asking; are there plants that really make meaningful, or even just measurable amounts of oxygen without light?
(Or is the idea here that you leave your lights on at night and so actually any plant can make oxygen at night?)

Oh noooo the website did a rigorous mistake. It is true that CAM plants can absorb CO2 at night; but it is FALSE that CAM plants give out O2at night. They can do it only at presence of light.

@AlwaysConfused what are CAM plants? Could you include a link in your comment - or expand to an answer? This sounds like a very plausible scenario.

Thank you but it was just a short hint. To write a detailed, referenced answer (following community standards) it will take time whereas I'm busy with someother work now. However here I link the wikipedia page on CAM. In short, it is an adaptation to reduce stomatal opening at the daytime to save water.

@tomd someone else may take the ball because looks like upcoming 2 days I'll  not be able to write an answer following community standards. Also later-on I could write an answer?

@AlwaysConfused you can write answer anytime you want...write now, I am writing one (though it doesn't involve your point :)

@another'Homosapien' et al remember the question is primarily about oxygen production in the dark, not what the advertisers may have been confused about.

To the unclear what you're asking voter - I am asking if plants can make oxygen at night or not. Yes or no. I'll remove the word "these" from the title.

@tomd I'll do the reading you mentioned, thanks. I need to ease myself into photosynthesis slowly, from the edges. I know I should follow the electrons, but I'm curious how the two oxygens meet up. I wish I could see an animation, or read a description of what happens to the two oxygen atoms in the two initial water molecules.

@tomd wow - too many big words for me! :)

@tomd this sounds really interesting! There are a lot of big words here, and some of them seem important: https://www.researchgate.net/post/How_CAM_plants_handle_the_O2_evolved_in_photosynthesis_during_daytime My title says "...produce oxygen... without light" and the restatement at the end of the question says "...make...
oxygen without light..." so I think the answer as I wrote it is still "no" — but now I regret that I didn't say "...release oxygen..."

Short Answer: Any plant can produce oxygen at night, but plants cannot produce oxygen without light.
Longer Answer: It all comes down to spontaneity of a reaction i.e. whether a reaction can occur without input of energy or not.
Before we talk about spontaneity, I feel it better to first know about the process we're talking about here. In photosynthesis, the water-splitting reaction occurs in the oxygen-evolving complex through a process known as Joliot-Kok cycle (or simply, Kok cycle)1. Although, the complete mechanism of this process is not understood yet, the basic reaction can be depicted in a diagram as2:

(Pay attention that in the diagram, the time taken is in microseconds and even nanoseconds. So, at molecular level, oxygen evolution does not take minutes or even seconds! However, at larger scale, release of oxygen might take longer time since the formed oxygen has to pass through many fluids, like thylakoid membrane, stroma, chloroplast membrane, cytoplasm, etc. before finally coming out in atmosphere)
To know where the photons are required (since the above diagram doesn't talk about that), I'll let in another diagram involving the steps where photons come in (as depicted by Rutherford et al, 1989):

As you can see, Kok cycle does not get direct input of energy through photons. Rather, it is the high energy P680+ which oxidizes a redox active tyrosine (YZ), which drives the reaction forward (the actual process is much more complex, see another answer or Halverson et al, 2003 for details).
Now, talking about spontaneity of this reaction, oxidation of water into hydrogen and oxygen is an endothermic process i.e. it is non-spontaneous in nature. In fact, the process requires 475 kJ/mol energy for occurring (Wikipedia). This energy barrier is so large that in the Kok cycle too, 4 photons are required to bring about oxidation of 1 water molecule (generally, catalysts are used so that they bring down the energy barrier of a non-spontaneous reaction so that it can be performed under normal conditions). Nilsson et al, 1857 talks about free energy change ($\Delta G_0$) of the cycle. See the graph for free energy change:

As is clearly visible from the graph, a higher amount of energy is needed to oxidize water ($E_P^+, S_2 \rightarrow S_3$) and even higher for liberation of dioxygen from the complex ($S_4 \rightarrow S_0$) (though the free energy change is negative for the last step i.e. liberation of oxygen is spontaneous, still the overall energy is larger than that at S3). Thus, since the reaction requires overall energy input, plants cannot produce oxygen without light. Also, as you suspect already, the point here is the abundance of light from man-made sources which makes some plants able to produce oxygen at night.
BONUS: I'll add some details about the thermodynamics of the system (skip this part if you're not interested in maths). The basic equations I will use here are Gibbs Fundamental Equation ($\Delta G = \Delta H - T\Delta S$), Arrhenius Equation ($k = A \times e^{-E_a/RT}$) and Eyring Equation ($k = k_BT/h \times e^{-\Delta G^\ddagger/RT}$) and used data will be from Nilsson et al, 1857.
From $\Delta G = \Delta H - T\Delta S$, to make a reaction spontaneous ($\Delta G < 0$), either there should be release of heat ($\Delta H < 0$) or increase in entropy ($\Delta S > 0$). As we know now, the reaction is endothermic i.e. there is absorption of heat. So, there must be increase in overall entropy to drive the reaction forward. If you look at the graph for free energy change in different steps of reaction, it comes out to be like this:

In this, $\Delta G_0$ is overall energy change, $\Delta G_{in}$ is the required energy input (given by photons), $\Delta G_{ex}$ is final free energy change and $\Delta G^\ddagger$ is Gibbs energy of activation. Here, $\Delta G_{ex}$ (shown in blue) corresponds to only the entropy change when final products (oxygen and protons) are released from the system as there is no enthalpy change here.
In release intermediate stage, the mole fraction $x = 1$ for oxygen, whereas in dissociated product stage mole fraction for water $x_1 = 56 /( [O_2]_0 + 56)$ and for oxygen $x_2 = [O_2]_0 / ([O_2]_0 + 56)$ (assuming molarity of water = 56 M) since in the final stage, water or oxygen or both can remain binded to the active site.
For release of oxygen: $[O_2]_0 = 273~\mu M$ and $T = 298~K$
which gives $\Delta G_1 = -~T\Delta S_1 = -~314~meV$
For release of proton: $\Delta G_2 = -~T\Delta S_2 = -~516~meV$ (since there is no enthalpy change, $\Delta H$ is neglected)
Now, $\Delta G_{ex} = \Delta G_1 + \Delta G_2 = -~314 - 516 = -~830~meV$
Also $\Delta G_0 = \Delta G_{in} + \Delta G_{ex}$
Since $\Delta G_{ex} > \Delta G_0$ therefore $\Delta G_{in} > 0$ i.e. energy is supplied.
Now, for the reaction $~~P_{680}Y_Z^{ox}M_3 \rightarrow P_{680}Y_ZM_0 + O_2$ (for which we've made the above graph)
Time constant $\tau \approx 10^{-3}~s$
i.e. $1/k = 10^{-3}~s$
or $k = 10^3~s^{-1}$
Using Eyring equation $k = k_BT/h \times e^{-\Delta G^\ddagger /RT}$
We get $\Delta G^\ddagger = -~580~meV$
In other words $\Delta G_{in} \leq -~580~meV$
Again $\Delta G_0 = \Delta G_{in} + \Delta G_{ex}$
On solving, $\Delta G_0 \leq -~250~meV$
Again, from Eyring equation, we get $k \geq 10^4~s^{-1}$
The large rate constant shows that there is a strong driving force for release of oxygen from the system, which is very likely due to increased entropy of the final product.
Thus, the enzyme brings down the free energy of the reaction, but at the expense of an increased activation energy barrier. Coming back to the main point, since energy is supplied to the system for the reaction, the reaction is non-spontaneous. However, the last step of the reaction is spontaneous (as also seen in the first graph) because of increase in translational and rotational entropy of final products when they are released (in above calculations, we neglected rotational entropy because of lack of data). Also, the above calculations were only for the last step of reaction ($S_4 \rightarrow S_0$) to show its spontaneity. In all other steps, energy has to be supplied to the system to drive the reaction forward (as shown in both first and second graphs above), making the overall reaction endergonic. I hope this helps now.
References:
 1. Wikipedia contributors. "Oxygen-evolving complex." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 1 Jan. 2017. Web. 18 Apr. 2017.
 2. Oxygen Evolution - 1996, Antony Crofts, University of Illinois at Urbana-Champaign
 3. A.W. Rutherford, Photosystem II, the water-splitting enzyme, Trends in Biochemical Sciences, Volume 14, Issue 6, 1989, Pages 227-232, ISSN 0968-0004, http://dx.doi.org/10.1016/0968-0004(89)90032-7.
 4. Halverson, Kelly M., and Bridgette A. Barry. “Evidence for Spontaneous Structural Changes in a Dark-Adapted State of Photosystem II.” Biophysical Journal 85.4 (2003): 2581–2588. Print.
 5. Wikipedia contributors. "Heterogeneous water oxidation." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 18 Apr. 2017. Web. 18 Apr. 2017.
 6. Håkan Nilsson, Laurent Cournac, Fabrice Rappaport, Johannes Messinger, Jérôme Lavergne, Estimation of the driving force for dioxygen formation in photosynthesis, Biochimica et Biophysica Acta (BBA) - Bioenergetics, Volume 1857, Issue 1, January 2016, Pages 23-33, ISSN 0005-2728, http://doi.org/10.1016/j.bbabio.2015.09.011.

Oh my goodness this is very helpful, thank you. I'll take some time to read through it. Is the $\ce{O2}$ released in milliseconds all the way to the air, or does it have to diffuse through some fluid first?

And if you catch your breath, I've asked another photosynthesis question as well.

I would like to add CAM plants, they open their stomata only during the night, to absorb CO2. For the rest of the day it is closed. So the O2 produced through calvin cycle is not released during the day, does it release at night, is the question. I couldn't find much research on this, possibly not much has been done. I didn't check if the plants enlisted in OP's website are CAM. They might be. Interesting though. Researchgate has a discussion on this.

I'm sorry, not Calvin cycle, through photolysis.

Won't be writing answers anymore. It just takes too much time.

I've just seen the "enhancements" here - will need a bit longer to read it all, but wow! In the mean time, I have this affliction that causes me to spot tiny errors without even looking - the units here should be inverse seconds: $k = 10^3~s$

Junior high physics teacher was obsessive about units, taught us to look at the units before looking at the equation. Now it's just a reflex I must live with ;)

Can you please stop excessive commenting and move over into the chat for this?


text:
What species is this bird (found in Cousset, Switzerland)?
A friend of mine saw that bird in Cousset, Switzerland but it doesn't look like anything we know or we've already seen before around here. Does anyone have an idea of what species it could be? Thank you in advance (and sorry for the bad quality of the picture)!

This is really hard to tell given the quality of the picture. What size was it?
Could be Emberiza citrinella, the so-called yellowhammer - a year-long resident in Switzerland. It is about 16 cm in size and its breeding season starts beginning to mid-April and males are advertising for females in a golden plumage.

Again, this is only a best guess and without a better quality image it can never be more. RHA pointed out in the comments that the head of the bird in your image appears to be darker than one would expect in E. citrinella, suggesting it could also be E. melanocephala - the black-headed bunting, Spinus spinus - the Eurasian siskin, or Serinus serinus - the European serin. But consider this:

The bird on your picture appears to have a somewhat dark head but it does not seem to be black (but with the resolution it is hard to tell). E. citrinella males have brown stripes on their head that can be more or less pronounced (see examples in Google search for yellowhammer) - blurred, this fits the brown head in your picture.
In your comment, you give the bird's size as the size of a house sparrow which exactly fits E. citrinella.
E. melanocephala males have a pitch black head and the range it can be found does not fit your location. There are reports of vagrants but in combination with the brownish head in your picture this seems somewhat unlikely to me.
Sp. spinus and Se. serinus are smaller (max. of 12 cm in length) than what you describe.
Se. serinus is a partial migrant in Switzerland which decreases the probability of finding it in April, compared to a year-long resident. Additionally, it also only has brown stripes on its head.

In summary, I think the the most parsimonious call is that the bird on your picture is E. citrinella. However, keep in mind that it could also be one of the other species mentioned above, with E. melanocephala - given your size description and the dark head - perhaps being the second most likely identification.

My friend says it was as big as a house sparrow... We think he escaped from somewhere and I thought of an american goldfinch first, but I don't really see why a goldfinch should escape from somewhere in Europe.

@AlissaDeschamps: That fits the size of E. citrinella as well.

I know, I was just reporting the exact words of my friend ;) Thanks for your help anyway :)

The bird in the (vague) picture clearly shows a black head, that lacks in E. citrinella. Can you explain how you can rule out other species that have a dark head, for example Carduelis spinus, Emberiza melanocephala and Serinus serinus? @AllisaDeschamps

@RHA: I mentioned the bad quality in the picture. There is a reason why I think it is most likely E. citrinella. I'll edit the answer to make that more clear.

Thanks for your edit. I am still not convinced it is E. citrinella, but your answer reflects the doubts now well enough IMHO.


text:
Is Bramble (blackberry bush) carnivorous?
I have come across this video which put forth the hypothesis that bramble actually qualifies as a carnivorous plant.  The observations that have led to the hypothesis are:
1. Sheep getting caught frequently in bramble
2. Sheep will die  without human intervention.
3. The rotting corpse of the sheep will nourish the plant for many days.
4. The thorns angle inward -- supposedly evidence for adaptation that helps trap prey animal.
I agree , on the surface it looks plain silly but that is a reflexive reaction, not an argument.  Is this a plausible hypothesis? If not , please give reasons.

Could you provide more information about why this plant may be carnivorous?

Are you using the word 'carnivorous' as meaning "meat eating"? What is the (unstated) hypothesis that the plant is carnivorous? ("The plant is carnivorous" is not a hypothesis. It is a conclusion.) Please do not simply link to a video; summarizing the relevant content is more likely to get you a good answer. Thanks.

@anongoodnurse: There are also some of us for whom video is not a good way of conveying information.  Even if I chose to spend my time watching, the amount of information I'd retain would be significantly less than if it was presented as text.

@jamesqf I understand your point, but in that case we would have to present information always in many different ways to provide for all types of learners. For me, a mp3 file with spoken word, please.

Voted to reopen and flagged. Thanks for the edit!

@skymningen: But StackExchange is fundamentally based on the written word.

Even if the adaptations to tangle were well supported, brambles would still not be carnivorous.
Carnivorous plants release digestive enzymes to digest their prey or have other adaptations specifically to pull nutrients from the things they kill. Brambles would have to rely on something else to rot the carcass and pick up whatever trace nutrients that get released into the soil like any other plant. Brambles tendency to tangle could just as easily be a defensive adaptation meant to encourage herbivores to avoid it. Without any specific adaptations to uptake the nutrients from killed animals, classifying them as carnivorous would be premature.

This is really more of a comment than an answer, but I'd challenge most of those premises.
1) Sheep getting caught.  But (AFAIK) wooly sheep are the (recent, in evolutionary terms) product of human breeding.  Blackberries &c wouldn't have had time to evolve specific mechanisms to trap them.  Most animals have relatively slick hair (or none, as with humans), and don't get trapped.
2) Domestic sheep don't really exist in the wild, do they?  So there almost always will be human intervention.
3) Does rotting meat provide needed nutrition to the plant?  I grow blackberries & raspberries, and they seem to do just fine without dead critters.
4) But if you spend time in places where blackberries or other brambles grow wild in some profusion (western Oregon, for instance), you do not notice (or at least I never have) an abundance of dead critters in the bushes. (Addendum: and dead critters of significant size, say larger than a rabbit, tend to be noticable, especially when you hike with dogs :-))
So I have to conclude that there's something wrong with this claim.

I had a farm so cluttered by brambles that I considered calling it Bramble Hill. My goats loved to eat brambles (I think they're well known for it), and, as you said, slick hair means no problem. Never lost a goat to brambles nor found any dead animals amongst them.

I saw the same video and thought it was interesting. While others who didn't bother to watch the video might miss a few interesting points.
Video link
https://youtu.be/RuzLXxbGc4c
It was pointed out that the thorns didn't stick straight out defensively as many thorns do, but rather raked back, thus grabbing and making it difficult to pull away.
Based on this article, it appears it would be more appropriate to call bramble "Protocarnivorous".
https://en.m.wikipedia.org/wiki/Protocarnivorous_plant

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Are two colors (red + blue) necessary for LED grow lights, or would either color be sufficient?
Below are some chlorophyll absorption spectra from other answers here. There is strong absorption at both the blue/violet end, and the red end of the spectrum, and presumably both of these contribute to steps in water splitting used in photosynthesis.
Do the two broad but widely-separated peaks correspond to different steps, so that both are required? Or is it sufficient to have light present in one band alone?
If both are required, how are they used differently?
If not, why do LED grow lamps have both? Would twice-as-bright light with either wavelength be just as effective and useful to plants?

That horribly un-natural purple light looks cool in high tech settings, but it's kind-of ugly in ones living room.
note: Originally I had though that Chlorophyl A and B corresponded to the two peaks, but clearly this is not at all the case. From here:

Both Chl-a and Chl-b primarily absorb red and blue light, the most effective colors in photosynthesis. They reflect or transmit green light, which is why leaves appear green. The ratio of Chl-a to Chl-b in the chloroplast is 3:1.

above: From this answer, also seen here.

above: x2 From this answer.

It's possible that white or yellow lighting might be less efficient for growing plants. (Then again, maybe not.) Still, perhaps you'd want to splurge on running possibly-less-efficient lighting, at least during the hours when you're sitting in your living room?

The plant uses light to produce energy but also as a signal of how and when to grow (phototropism, photoperiodism). In the context of your question I'll first cover light-harvesting in photosynthesis and then phototropism.
Tl;DR
Blue and red light are important for plant growth. Red light is the main one in photosynthesis and if a plant is exposed to another low intensity, full spectrum light source there is no (theoretical) need for a blue LED.
Photosynthesis

(from WTAMU)
The light from the sun arrives in many wavelengths, no one material can use all this energy. In photosynthesis light is intercepted by an antenna, a Light Harvesting Complex, made of different pigments, each intercepting photons in a unique energy level (wavelength). These antennas are situated around a reaction center and redirect the photons to it. Only the reaction center releases an electron to the electron transport chain. The pigment in the reaction center is modified chlorophyll a. In PSII (Photo System II, beginning of the chain) it's called P680 and in PSI it's called P700, the number denotes the excitation wavelength. The goal of the antenna is to gradually redirect photons to the reaction center and to its energy level (reducing the energy).

(Pandit, Anjali & Holzwarth, Alfred & Groot, Huub. (2006). Harnessing Solar Energy for the Production of Clean Fuels.)
When a photon excites a chlorophyll molecule this energy needs to dissipate in some manner. Energy dissipation from a blue photon excitation is too fast for it to be captured by the electron chain reaction. All the of the energy difference between blue and red photons is wasted (regarding photosynthesis).

(Dr. Shilo Rosenwasser presentation)
From the chlorophyll and other pigment explanation we understand that using any light except red is wasteful regarding energy conversion efficiency, the plant photosynthetic system will "ignore" any energy extras above the red photon.
Phototropism
The stem of the plant grows towards light and the roots grow away from light, this phenomenon is easily observed by looking at plants close to a window, they tend to "look out" of the window. This means that plants have a sensor for light.
This observation was first correctly analyzed by Darwin (a historical review).
Without blue light plants will elongate in an proportional way called etiolation. Etiolation makes a deformed, fragile plant because of its mechanism. Without blue light a plant will etiolate, even with enough energy for photosynthesis.
It is important to note that the light intensity required in light-sensing responses is much lower than the intensity required for photosynthesis.
It is also important to remember that blue & red light take part in other critical steps in plant growth like germination and flowering.
In conclusion
Red light is the major contributor to photosynthesis. Blue light indicates to the plant that there is light and it should start growing normally and do photosynthesis.
In the LiCOR photosynthesis measurement instruments the default settings are 96% red light and 4% blue light, showing that empirically red light is relevant to photosynthesis and blue is for signaling.
If your plants are exposed to some natural light or white light (from a window or lamp in your living room) I don't think that you need to supply blue light as they will get the required amount from those sources. Growing in a controlled, closed environment does require the blue light.

Fascinating! Thank you for your thorough and well-organized answer.

tl;dr: Sort of?
Logically, either red or blue light should be sufficient. Chlorophyll a and chlorophyll b preferentially activate different photosystems, and both photosystems are required in green plants.
Practically, we're in luck and someone has actually done the experiment.
As the original study reports, plants need a little blue light to grow into the right shape. Red-only plants produce oxygen and grow, but they take weird shapes. It seems like plants can grow on red light, but they use blue light to work out where light is. See here for a reasonably lengthy treatment on most of the obvious combinations.

These are very interesting, thanks! It certainly seems that red-only is suggested to be all that's needed for substantial photosynthesis (though it's not clear yet if there is a slight improvement in photosynthesis or not with blue added) Has it been stated anywhere that blue-only is not sufficient? Since the absorption spectra show big peaks at both ends, I'm asking if either one is fine. Will plants not grow with blue-only?

Uh, long story short: I don't know and I also don't know how to find out. (Other than the obvious way)

OK thanks. I think the idea that multiple bands of wavelengths are important for more than just photosynthesis rate is really interesting. I have read that the newest LED modules used on the International Space Station will now include Green light as well, though I'm not sure if that's for the plants, or for the astronauts to improve their ability to do visual inspection.

I've slightly modified the wording of the question, changing "one color" to "either color" in two places. I didn't realize until now that it's did not read clearly.

Hi, I've un-accepted your answer because both of your links to hortsci.ashspublications.org have broken/rotted and you only included minimal information from them of them within your answer itself, and actually not even the titles of the works nor the authors' names. This is now an unsupported answer; is it possible to find new links to support it? Thanks!

@uhoh: Being an abuser of bare links in unpaid forum posts myself, I should illustrate that the information is recoverable:  https://pubmed.ncbi.nlm.nih.gov/11537611/ https://www.researchgate.net/publication/263124879_Plant_Productivity_in_Response_to_LED_Lighting  Just do a web search for the quoted link.

@Mike please feel free to edit the post; once it's in good shape I'll accept it. Thanks!

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Could plants do photosynthesis at moonlight?
Related to this and this but not exactly same; could plants do photosynthesis at moonlight or more dim-intensity light?

Of course they can and do, except in total darkness (spectroscopically, only bands in the far red and in the blue spectra matter - blanking these affects 'total darkness').
In photosynhesis a photon is adsorbed by Photosystem II to break down water into oxygen and protons in solution. Another photon must be adsorbed by Photosystem ! to power the enzymatic machinery that make NADPH and ATP that power the Calvin cycle.
We know the sun powers photosynthesis effectively. The sun produces somewhat less than 100,000 lux (lumen per square meter). Moonlight is one one millionth of this or about 0.1 lux. One lux is something like 10^15 photons per second (per square meter); so moonlight provides something approaching 10^14 photons per second to drive photosynthesis. The spectrum of moonlight is not markedly different from that of sunlight. So, moonlight provides an ample number of photons per second per square meter to power photosynthesis.
The trouble, though, is that the rate of photosynthesis is low compared to the rate of metabolism in the rest of the plant. So, in effect, the plant gives off carbon dioxide by night and oxygen by day even though both gasses are being emitted all the time.
EDIT (per request) some references:

Photosynthesis
Respiration
Moonlight lux versus sunlight
Photons per second in a lumen

Nice answer, upvoted and accepted. But you could add some reference so that the information and data become verifiable; to meet community standards


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What is this insect in North Carolina?
This insect is in my house in North Carolina, USA. I think it shares similar body features of that of a wasp, but it is far too narrow and has what appears to be a long stinger. What is it?

The long stinger is an ovipositor. (https://en.m.wikipedia.org/wiki/Ovipositor?wprov=sfla1)

This is some species of ichneumon wasp.
The ichneumon wasps are parasitoid wasps in the order Hymenoptera. They commonly parasitize other invertebrates, especially larvae and pupae of Coleoptera, Hymenoptera, and Lepidoptera.
Specifically, this appears to be Dolichomitus irritator.

 Photo credit:  Thomas wilson
Here's another specimen of the same species found in Weymouth Woods-Sandhills Nature Preserve, Southern Pines, Moore County, NC:

 Photo credit:  Dorothy Pugh
You can find additional high-quality images from Jeff Tome's Flickr page.
I could not find too many sources with good information about this specific species. Fontanelle Forests' Nature Search provided the most complete info:

Description: 7/8 inch long, not including the ovipositor.  The head and thorax are black.  The abdomen is red-orange.  The legs are yellow and orange.  The antennae are black.  The black ovipositor is at least as long as the body and head.
Ecology: Parasitoids of many woodboring insect larvae including long-horned beetles, weevils, metallic wood-boring beetles and some moths that are wasp look-alikes.
Taxonomy: In the subfamily Pimplinae, which has 180 species in 28 genera in North America.

Thank you very much, I thought it had to do something with wood

@Evander_C Some additional info: the long ovipositor has a purpose, but it isn't used for making holes in wood. Other species, like solitary bees lay eggs in existing or newly made holes. They make small walls between each egg (actually they also put eggs with females deeper into the wood). The longer your ovipositor, the more eggs the wasp can reach. A beautiful example of Ecology and evolution if you ask me.


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The Identity of this Lepidopteron
I snapped this picture on a walk in the Pacific Northwest last week, and, being new to entomology, cannot manage to identify whether this is a moth or a butterfly.

It seems to have the coloring of a moth, yet it was out around 4-5 PM, with the sun still shining brightly. Its antenna look like a butterfly's, but its face (particularly the eyes) seems to be that of a moth. The wings are folded up like a butterfly (in another picture of the lepidoptera), but they look quite drab for a butterfly. Any help?

This looks like the Satyr Comma or Polygonia satyrus.
Characteristic of this species is a dark border near the tops of wings, fading near the bottom. They are common across the Western United States and Southern Canada.

For more information on this species, try this link and this link.
To differentiate between moths and butterflies you can look at the anntenae. Butterflies often have a bulb at the end whereas moth antennae are feathery or saw-edged.

Looks right to me. Nice find!

The hindwing submarginal pale spots of the two photographs show clearly that two species (both in Polygonia) are involved; in the species of the answer, these spots are fused past the tail, the species of the question has two separate spots past the tail (which condition is true for three of the four Pacific Northwest species).

This is an anglewing (genus Polygonia), but the hindwing submarginal spots are more consistent with the Zephyr Anglewing (P. gracilis zephyrus); see http://www.butterfliesofamerica.com/L/t/Polygonia_gracilis_zephyrus_a.htm for several photographs of set specimens and living butterflies.  For future reference on photographing this genus: showing the underside is often more useful than the upperside.

Arthur, I believe you're right. What is the best way for me to change my answer? Should I delete mine and upvote yours or make edits to mine?

As for my answer, I'm no longer as convinced as I was when I wrote it; I had initially eliminated another species due to its rarity (Polygonia oreas: see http://www.butterfliesofamerica.com/L/t/Polygonia_oreas_a.htm for examples, paying closest attention to the first three subspecies shown); reading Pyle's The Butterflies of Cascadia now convinces me that species is an even better match (underside figured on page 315; the main species account on page 319).


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What is this insect (Egypt)?
I am from Egypt, and I found this insect in my house. It's slow when it moves, and I didn't see it fly. It's green (my phone camera didn't get the colors right).

This is some species of aphid.
Most people are familiar with the wingless stages of these insects that crawl on and eat plants. There are also winged 'alates'. For example, see the life cycle of the soybean aphid:

Due to the picture quality, I'm uncertain about the exact species. However, I can show you alates from some similar looking species:
Nasonovia ribisnigri (Currant-lettuce aphid)

 Source: influentialpoints.com
Aphis pomis (Green Apple Aphid)

 Source
Macrosiphum rosae (Rose Aphid)

 Source: Bernard Dupont
As you can see, these phenotypic characteristics (i.e., green body with black head, clear wings, black/green striped legs, green cauda and black cornicles) are present in numerous diverse species of aphids.
Perhaps you could comment on nearby crop plants or garden plants near your house or produce that you've recently purchased or brought into the house. Sometimes knowing possible host plant species can help narrow down possibilities.


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Is Berlin patient immune to HIV after bone marrow transplant?
Is the Berlin patient here : https://biology.stackexchange.com/a/39364 become immune to HIV after bone marrow transplant? Or in other words: Can he get HIV infection again?


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What does the species name 'fistula' mean?
Cassia fistula is tree with yellow flowers. As a medical student what amazes me is that the word fistula implies other meanings. A fistula, at least in medical science refers to a tract with two epithelial openings.

Have you looked at pictures of the plant, especially the fruit? Fistula is the latin word for tube. It is used in medicine, but also in botany. So basically, the word fistula does not only imply other meanings, it has other meanings.

@skymningen could you post it as an answer? Yes now I recall. It has long tube shaped pods. Thanks

The botanic and medical term fistula is directly derived from the latin word fistula meaning tube or pipe.
Both the medical fistula and the fruits of the Cassia fistula tree show phenotypes similar to a tube.
I will spare everyone the medical example picture, but here are the fruit of Cassia fistula, which are sold as "manna":


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Why can't we grow more teeth?
A similar question but about teeth healing themselves is Do teeth have the capacity to heal?.

So I understand that teeth have the capacity to heal themselves to a certain degree. It appears to be that part of the reason they can't heal all of themselves is that they are not surrounded by cells. In that case why can't we grow teeth back?
If a tooth is grown in the gum, or somewhere else, it would be surrounded by cells and so should be able to grow back right?
It appears that sharks can grow their teeth back:

New teeth are continually grown in a groove in the shark’s mouth and the skin acts as a “conveyor belt” to move the teeth forward into new positions.

Why can't we do this?

Short answer: Teeth are formed prenatally in tissue destined to become bone (the mandibles), that is, in the embryo. Once they have formed, they can grow and develop, but new teeth do not form after mid-gestation. Shorter answer: that's how the genes for tooth formation expression are regulated. It's like asking why we don't grow a new leg if our leg is amputated.

@anongoodnurse why not put that as an answer?

@another'Homosapien' - I don't know;  "because" is not much of an answer.

@anongoodnurse it would be enough for an answer. I might edit that up too :)

Possible duplicate of Why do some bad traits evolve, and good ones don't?

Note everything but mammals continue to grow new teeth, sharks are not the weird ones, mammals are weird for not doing it

Unfortunately, the answer to your question isn't as well researched as other areas, I believe...let's add some complexity into this.
You're correct, teeth does "grow" in the gums. And it does start off surrounded by cells (look up: tooth bud, cap, bell stage)!
The tooth originates from an interaction between the ectomesenchyme (likely originating from the neural crest cells) and the epithelium of the mouth when it is forming while you're still an embryo in your momma's tummy.
Unlike sharks, which are homodonts (meaning, their tooth are all of one morphology), we are heterodonts (e.g. we have different shaped teeth - e.g. molars, canines, incisors, premolars). There are a couple of theories to why this occurs (look up: clone model, field model, odontogenic homeobox code - a combination of all these theories). Basically, a bunch of genes transcribe for proteins and signalling factors that create the complexity of your tooth shape and position in the mouth.
Basically, this means, our teeth are going to take longer and require more energy and effort to carve into (yes carve! lot's of the tooth shape is create by apoptosis of the regions around the "cusp" area when it is developing).
When your primary/baby teeth pop out, they serve functions such as developing speech, allowing you to eat, strengthening your jaw muscles (which in turn helps to develop your mandible and shape of the face), all this so you can have a great bite when you get older!
Luckily, sharks don't speak much underwater, so they probably don't give a poop about having properly lined up teeth. Their teeth grows everywhere. Proper bite for eating various nuts, fruits, meats and vegetables? NAH. WE JUST CHEW OFF LEGS. WE CAN ONLY SHRED STUFF. Sharks need strong ankylosed teeth (ankylosed = like an anchor? teeth are anchored into the mandible of the shark).
In contrast, humans have teeth in gomphosis (sockets), which gives our teeth some cushioning and sense of proprioception (the sense knowing how hard you're biting) when we bite on something extremely hard, to prevent us breaking our teeth - thus helping us preserve our teeth. Sharks don't have that, they just break their teeth.
Humans do finally replace their teeth, after our jaw grows enough for us to accommodate them at a genetically planned stage. This happens by tooth germs (cells) being bud off (like a flower yes :D) from the baby teeth. Note though, your 1st adult/permanent molars are already beginning to form when you're still in your momma's tummy.
I believe that the continuous creation of teeth requires more energy, but takes less time (sharks). For humans, one time creation of teeth requires less energy, but takes wayyyyy more time (and also has to be timed correctly with all our other growing bits).
TL;DR Evolutionary reasons and different functional uses of teeth between sharks and humans probably determine why we only have two sets of teeth (diphyodonts). That being said, it would be cool if we were like rats (have molars/incisors) though, which replace their teeth anytime its lost. Maybe one day we can evolve into it? Yay!

Some interesting points: You mentioned teeth "healing".
Your teeth is made up of enamel on the outside, which is NEVER replaced. It "heals" by remineralisation which is not exactly the same as growing new crystals on top of it. Kinda complex, won't go into it.
However, your teeth is always forming new dentine, which is below the enamel. In a way, your tooth really is growing back all the time. Because a new layer of dentine is deposited everyday (like...4 micrometers). This is because the dentine producing cells, called odontoblasts, are still around. In contrast, the enamel producing cells, called ameloblasts, are removed when your tooth has developed. I THINK, the reason is to make space in your enamel so it can be fully mineralised and completely filled up by hydroxyapatite. (Too much fluoride when young can block this removal of ameloblasts and its proteins like amelogenin and enamelin = forming holes, which cavitate resulting in fluorosis).
Hopefully all that answered your question. But, it was fun for me to rant anyway. Cheers.

Nice effort on this answer! However, please provide some resources or citations to back-up your claims. We want all of our users to feel confident that the information they read on Bio.SE is well-researched and reflects scientific understanding and not simply opinion. Thanks!

Actually it is quite well researched, Mammals are the only group of animals that grow only a limited number of teeth but socketed teeth and heterodont teeth are not limited to mammals.

Also rats do not replace lost teeth, they have incisors which never stop growing, those are very different things.

Because mammals had to be different, and spent way too much of their evolutionary history being tiny short lived creatures.
No seriously, mammals are outliers in this. Growing endless numbers of teeth (Polyphyodont) is the normal aka basal condition in vertebrates. Every other group of animals with teeth just keep replacing them forever. Mammals uniquely have lost this ability.
All mammals grow a fixed number of teeth, most are diphyodont growing their teeth in two distinct sets, a few mammals (elephants and kangaroo) spread their number of teeth into multiple series but the total number of teeth they produce is still fixed, they are sort of pseudo-polydont. Some whales produce a much larger number of teeth but the total number of teeth is still fixed.
Why are mammals weird, because the ancestors of all extant mammals were small short lived insectivores. If you are short lived insectivores wear is insignifiant on teeth and dislodging them is a minimal risk. Multiple sets of teeth is not a significant advantage. What is a significant advantage is tightly occluding teeth, that is teeth that fit together very tightly with multiple cusps, this shape is perfect for processing insects into digestible pieces,  but it does not work well when teeth are replaced. The current thought is that mammals repurposed or lost the genes that allowed for new tooth bud formation. Many believe the genes were repurposed possibly into some of the genes that control tooth shape allowing the complex tooth structure mammals have. This is difficult to test but is supported by the fact the groups of mammals to increase the number of teeth, whales, armadillo, and some seals, also have extremely simply tooth structures and high numbers of anomalous teeth, that is teeth with seemingly no controls on their shape. Although I should note extra erroneous teeth occasionally occur in  nearly every mammal line.
The exact changes have not yet been discovered and is an are with much interest. We know why pretty well even if we don't know how. Although there is some fascinating work being done by studying how reptiles continue to replace teeth throughout life. Certain basal cell lines persist in reptiles but completely differentiate in mammals during early development. Whales get around this by making a lot of new buds early on and holding on to them, but they still can't make new ones past a certain point.
Also related, why mammals have bigger nerves in their teeth.


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What is mold detection threshold in humans?
I managed to find primary taste detection thresholds, e.g. for sweetness it's 1 part in 200 of sucrose in solution.
Recently I've noticed that I can detect mold smell/taste even if there are no signs of product getting spoiled.
What is the mold detection threshold in humans, and is that a dangerous amount?

Different molds might have different taste. Thresholds can be set for primary tastes, and maybe for very basic molecules and compounds, but it is unlikely to be able to find one consistent threshold for something as varied as mold.

Maybe asking for one consistent treshold is too much, but some numbers would give at least an overview. It's an interesting research topic, shame it looks hard to do at home.

It depends on the mold. For example, humans can smell octenol in ppb concentrations[1], presumably long before any toxic effects of this or other compounds produced by molds. Octenol is produced by many molds, always through breakdown of linoleic acid (part of many triglycerides, i.e., fatty oils present in most food).
Update: another example of a non-toxic mold is that causing cork taint. The responsible substances (trichloroanisoles, TCA) can be tasted by humans in wine at 2-4ng (nanograms) per liter wine.[2]
[1] M. J. Saxby: Food Taints and Off-Flavours., 2. ed., Springer 1995, ISBN 978-0-7514-0263-6, S. 210–212.
[2] http://schaechter.asmblog.org/schaechter/2018/07/tainted.html


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How do plants maintain air spaces in leaves?
As we know, there are air spaces in the mesophyll layer which allows carbon dioxide to diffuse in and oxygen to diffuse out, but cell membranes are partially permeable and allow water to diffuse to regions with lower concentration. Yet these air spaces still manage to not get flooded by liquid water.
How does this happen?

Welcome to Biology.SE! This question is off-topic since you don't show any research effort. Also, it might be a better fit for Physics.SE

I in-fact did some research but i came up empty handed as all the resources i have got my hand on to don't address this problem directly and the only helpful resource was this research https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1066361/pdf/plntphys00565-0087.pdf

That is wrong, yes it will displace it eventually making it move out the stomata unless ur saying that air is compressed (which is not and can't be as its content actually diffuse to and from cells) that it won't let water molecules through the pores that it fits through which again can't be the case, it is water and it can go out of the cell but why doesn't it?

in the end all sciences interlock, diffusion and osmosis for example are from physics, so if a question is asked about it relating living things u can't just claim it is off-topic

There has not been not much research on this topic, which has caused lack of definite answer. Sibbernsen et al, 2017 performed a study on response of stomatal opening on filling these air spaces with water. They suggest the existence of a vapor-phase signal (from water) that originates in the mesophyll and causes stomata to open in the light. In another research, Wiebe et al, 1976 were able to remove the air spaces with the use of paraffin oil which infiltrated the spaces. They show that leaf air spaces contain invaginations which are extensions of air space system and increase conductivity of CO2 to the chloroplasts which line these invaginations.
Stomatal transpiration gives a clue to this. When the stomata open, they expose the internal environment to the atmosphere. Due to this, the air spaces get filled with water vapors which, due to concentration gradient, flow outwards from the leaf. To maintain the inner water vapors, more water is evaporated from the nearby cells, which leads to more transpiration. This hints that some water is present all the time in these air spaces in the form of water vapors. However, when the concentration of vapors becomes high, the nearby cells might take in some water or the stomata might open to maintain the concentration. See this article for some details on this.

At last, there is Woolley et al, 1983 which concludes that the mechanism behind the maintenance of these air spaces is still largely unknown.


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Could we eradicate mosquitoes?
Researchers have proposed the application of CRISPR/Cas9 and gene drive to genetically alter wild mosquito populations such that they don't transmit malaria. The government of New Zealand has announced a program to eliminate several invasive mammals from that island, also using gene drive (among other things).
Could we use this technology to completely eradicate from the world all species of mosquito that prey on humans? Also, could we accurately predict the extent of the resulting ecological disruption so we could decide if it was worth it?

"Primarily opinion-based"?

Could we use this technology to completely eradicate from the world
  all species of mosquito that prey on humans?

Yes, implemented correctly, a gene drive has this capability.

Also, could we accurately predict the extent of the resulting
  ecological disruption so we could decide if it was worth it?

The current scientific and political consensus is that, no, we can't predict the potential consequences with high enough confidence to move forward with such a large-scale manuever.
One of the leading scientists studying and improving gene drives, Kevin Esvelt at the MIT Media Lab, instead supports a "daisy chain gene drive" which is pre-programmed to weaken with each successive generation, allowing humans to effectively control the spread of gene drives to a specific geographic area and time frame.


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Fraction of naive T-cells in CD4+ T-cells isolated from whole blood?
Many papers isolate CD4+ T-cells from whole blood.
I am wondering approximately what proportion of naive T-cells there will be from such a sample? Are these predominately naive T-cells or are there more memory and effector cells?

are you looking for absolute numbers or relative amounts?

I updated the question. I just want a ballpark estimate. I do not have a biology background :)

Stemcell Technologies has a really good wall poster for this. You can enumerate roughly 80,000 to 760,000 naive CD4+ T cells from peripheral blood per mL. This is 1-10% of leukocytes.
One of the things you need to remember about memory cells is that they do circulate, but it follows that among the circulating subsets of memory cells, they highly express markers for lymph node localization such as CCR7 and CD62L. Their presence in the blood at a given time is influenced by a number of factors including disease state.
Likewise, effector cells are programmed to localize within infected or distressed tissues through the actions of chemokines and chemokine receptors. The presence of effectors will depend on the same sort of factors, and as effector T cells, they are typically either made anergic and die by apoptosis or differentiated into memory cells.


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What is this spider? Two black stripes

When I opened my front door, there were five of this type of spider sitting on the door. I can't quite find anything online matching the two black stripes on it's back.
I vacummed them up before I realized I should identify them, so the above picture is the only one I have available. (I like spiders, but there were too many.) I'd feel more comfortable if someone could identify the spider and determine it's threat level.
Details:

Inch or so longer
Brown
North East Wisconsin
Wooded Area with little to no grass
Mile away from lake Michigan
Jumpers
Party of about 5
Door was in direct sunlight

It's hard to see from where the picture is a bit blurry, but does the spider look anything like this or this? I'm assuming the legs are different..

It's like, a mix between a nursery web spider and a wolf spider..ahhh.

It musb be a Lycosa erythrognatha

Judging by the stripes, it's most likely a wolf spider.

If they didn't have a web I would say they're almost certainly wolf spiders, since they don't build webs. Like most spiders in North America, they are harmless to humans.

The stripes in your specimen are drastically different from the OP's spider. This is not a good answer. Please consider updating with more evidence.

The family of Lycosidae (wolf spiders) is correct, but it is hard to justify with evidence aside from the general shape/proportions and colour and the geography of the observation. The most telling attribute to ID wolf spiders is the eye arrangement but they can't be seen in the quality of the pic provided in the question.

The spider in the original post is probably genus Gladicosa.

I think the spider you have found must be https://en.wikipedia.org/wiki/Tegenaria_domestica
In europe this is called the Domestic house spider,It can bite humans and pets the bite is painless.
This spider is common in Europe-USA-Canada.

No, the pictured specimen is not T.domestica or any funnel weaver. It does not have the abdominal markings or leg annulations or spinnerets. The spider in question is most likely a wolf spider.

@JimN thank you for the feedback,if it is a wolf spider you should upvote the other answer it is how our site works ,good answers should be upvoted and bad answers like mine should not.you might consider making an answer to the question yourself.


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What are important temperature breakpoints for plant distributions?
I am working on a climate classification system. Some previous works like Koppen and Trewartha use temperature breakpoints of 18℃ monthly minimum of daily average to delimit tropical climates, and 0℃ monthly minimum of daily average to distinguish subtropical from continental (Koppen only).
The first question, is there any scientific basis for these specific temperature breakpoints?
As an example of what I am looking for, I want to point out something in plant distributions in the area of the world I'm most familiar with; the South of the US. In Atlanta, where January averages are 6.3℃ and lows are 1.3℃, most of the natural trees you see around are either conifers or deciduous hardwoods (Oaks, hickories, yellow poplar (Liriodendron tulipifera) and sweetgum (Liquidambar styraciflua). However, towards the coast in New Orleans 11.9℃/7.1℃ or Savannah 9.8℃/3.7℃, there are a lot more evergreen non-coniferous trees. If you look at the (very similiar) distributions from Wikipedia of evergreens such as southern magnolia, live oak, or swamp laurel oak, you can see that there is a cline where the coolest month-averaged daily temperature goes below around 6-8℃ where these evergreen plant no longer grow.
So the general second question is, are there temperature breakpoints that are significant in controlling what sorts of plants can actually grow in an area?

Can't help with citations.  For temperate climates there are several critical temps that I know of:
First one is 0 or possibly -2.  The freezing point of water.  Most plant cells have enough dissolved material in their sap/protoplasm that there is 1-2 degrees of freezing point reduction.
Next one down seems to be somewhere around -10 C.  There is a big reduction in plant species counts around this temp.
Not sure where the next one is.  Jack Pine can tolerate temps down to -60C  Apparently their protoplasm has enough sugars and alcohols that it becomes a glass -- no expansion.

Climate imposes other limits.

I bought 500 mountain hemlocks one year.  Everything I read said zone 3.  Maybe for the tops.  Where they grow, there is typically several feet of snow in winter.  Roots never got below freezing.
In our region of central Alberta Crimson King Norway maple is hardy -- most of the time.  If it gets cold early, say November, it kills the buds.  It's not just how cold it gets, but when and how fast it gets cold.
Near Edmonton we can grow a variety of birches.  Calgary 300 km south is a growing zone warmer than us, but birches don't do well there.  The chinooks are warm enough that they break bud, then the buds die when it gets cold again.  Other plants avoid this by having a chilling requirement matched to our winters.
Our winters are very long.  Some of the problem isn't cold as much as desiccation.  In some cases a warmer winter will be more fatal -- warmer air can draw off more moisture from buds and twigs.
I think there are temps above freezing that are important:  When trying to grow eggplant, any day that got below +10C seem to make the eggplants sulk and do nothing for about 3 days while they were recovering.
Another critical temp is in the high 80's/low 90's. (Farenheit)  Many plants shut down photosynthesis to conserve water.  Greenhouse operators go to great lengths to keep their houses below 90 F


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Are humans the only mammals that are known to display homosexuality?
REQUEST: In this post I do not refer to, nor do I encourage reference to, any ethical/moral/emotional aspects of homosexuality. So please don't start an pro/anti- LGBT campaign in the comments section.

Are mammals (other than humans) known to engage in homosexual activity of any sort?
From the way I see it, homosexual activities carry no evolutionary or reproductive benefit: No offspring produced, no continuation of species...hence pointless.
Yes, I get that the "need to mate and to produce and protect offspring" is hard-wired into every (normal) mammalian brain. If I've interpreted this correctly; intercourse is a fairly energy-expensive act so if there were no immediately clear "incentive" for mammals to mate they wouldn't mate at all, hence heralding the decline and eventual extinction of a species. Nature solved this conundrum by ensuring that the brain would perceive intercourse as highly pleasurable, thereby securing the necessary "incentive" for mammals to mate.
The only "flaw" here, is that simply stimulating the genitals is sufficient enough to elicit a sensation of pleasure. So there's no real need to go through all the trouble of finding a suitable animal of the opposite sex and "do it" to feel good. A sufficiently intelligent mammal would soon figure that out; so this opens up two more possibilities: 1) Masturbation and 2) Homosexuality. (Since this post's on Homosexuality, I'm only going to deal with the latter)
So, a mammal intelligent enough to figure this out would have three options before it : 1) Heterosexual activity, 2) Masturbation, 3) Homosexual activity; the last two options being a way to bypass Nature's original intent.
So before I continue, I want to make what I mean by "homosexuality" very clear:
a) A being that displays option 1) or both 1) and 2) is heterosexual.
b) A being that displays options 1) and 3) [and maybe 2) too] is bisexual.
c) A being that displays option 3) or both 3) and 2) is homosexual.
[Just to make it explicitly clear, a homosexual will always steer clear of option 1)]
So let me just put all of that together and re-phrase my question:
Q- Are there any known instances where a (non-human) mammal consciously avoids heterosexual acts and instead prefers to engage in homosexual activity
Personally, I find this doubtful, since the existence of homosexuality (among humans) is the unintended result of Human self-consciousness/intelligence, something that other mammals apparently lack.
HOWEVER: (Considering another possible reason for homosexuality)
If occurrence of homosexual tendencies is (also) due to, say, the stochastic, faulty "hard-wiring" of the human brain due to mutation or damage to neural tissue (I'm not sure if this really is one of the reasons for homosexuality), then it would seem plausible that other mammals could also be affected by this stochastic "fault" and thereby display homosexual tendencies.

Have you looked at the wikipedia article on homosexual behaviour in animals?

@Remi No, no I haven't ._.

Sentences like the last two options being a way to bypass Nature's original intent. seems at least partially opinion based. You might want to have a look at the post How can homosexuality evolve despite natural selection?. Note also that there is no such thing as intention in nature but I suppose it was only a way of speaking)

@Remi "...I suppose it was only a way of speaking" It was ;)

Since answers will deal with homosexuality, I just want to mention that masturbation is quite natural as well, even porcupines do it. there are several hypothesis about its function with varying levels of support. Most likely several are true.

Although intuitively it would seem unlikely that there could be an evolutionary advantage to homosexuality (other than some theories regarding population control), homosexual behavior has been clearly observed in a variety of birds, monkeys and apes, lions, dolphins, lizards, insects, and plenty more.
The case of the bonobo is particularly striking in that homosexuality and bisexuality are more common than heterosexuality.  According to this Wikipedia article:

Bonobos, which have a matriarchal society, unusual among apes, are a fully bisexual species—both males and females engage in heterosexual and homosexual behavior, being noted for female–female homosexuality in particular. Roughly 60% of all bonobo sexual activity occurs between two or more females. While the homosexual bonding system in bonobos represents the highest frequency of homosexuality known in any species, homosexuality has been reported for all great apes (a group which includes humans), as well as a number of other primate species.

Although the complexity of sexuality likely points to the existence of multiple genes playing a role in sexual behavior and preference, at least one study$^1$ points to a single gene playing an important role in the sexual behavior, of female mice:

In this study, we generated mutant mice specifically lacking the FucM gene that encodes fucose mutarotase. The homo- and heterozygous mutant females exhibited deficits in sexual receptivity as demonstrated by a drop in lordosis score. Moreover, the mutants displayed masculine behaviors and preferences to female urine over male urine.

1) Male-like sexual behavior of female mouse lacking fucose mutarotase, Dongkyu Park, Dongwook Choi, Junghoon Lee, Dae-sik Lim and Chankyu Park, BMC Genetics201011:62, DOI: 10.1186/1471-2156-11-62

Regarding your first sentence: https://biology.stackexchange.com/a/7675/107

@kmm , interesting studies cited, particularly the twin study. Too bad there isn't more understood about the why of it, as in why heterosexual relatives of homosexuals are more promiscuous. Something to do with a balance of hormones maybe. Pretty complex picture. Thx for the link.

This reminded me of the rat overpopulation experiments from the 1960'sish, in a nutshell, if rats are allowed to overpopulate in a confined area, the males become stressed, violent and homosexual.

Whoa! That's something you don't hear everyday. Did the study suggest any reason for male homosexuality in this case? (I can't seem to think of any )

I can't remember any, other than as a means of displaying dominance, it has been used by armchair scientists as an example of why overpopulation leads to depravity and the "sin" of homosexuality. But mainly it's been used to guide animal welfare standards (at least in lab animals).


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Point mutation vs Indels
DNA sequence of a gene can be altered in a number of ways. Gene mutations have varying effects on health, depending on where they occur and whether they alter the function of essential proteins.
I know that there different types of mutations.
Missense, Nonsense, Insertion, Deletion, Duplication, Silent, Frameshift indel, Repeat expansion, Inframe indel, stoploss, splicing.
Can anyone please tell me which mutations are Point mutations and which come under Indels?
Thank you

What research have you done before asking it here?

A point mutation is a mutation causing the substitution, insertion or deletion of a single nucleotide.
An indel is a change in the number of nucleotides (either through insertion or deletion hence the name). When talking about indel most people (in evolutionary biology at least) refer to the insertion or deletion of a single nucleotide but some might refer to greater changes when talking about indels.
An indel which concern the insertion or deletion of a single nucleotide is a point mutation.


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Why are some bird species placed as family Incertae sedis while some families are simply monotypic?
The Bananaquit and Western Spindalis are passerines of Incerta sedis. But species such as the Osprey, Limpkin and Olive Warbler belong to their own, monotypic, family.
Why aren't Bananaquit and Western Spindalis simply assigned to a new family?


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Why do Guinea Pigs chirp / sing?
Ok, so this appears to be quite a mystery. Me and my girlfriend have 2 Guinea Pigs, 1 male and 1 female.
My girlfriend once picked up the female one and took her outside into our garden. The Guinea got scared for some unknown reason and jumped out of my girlfriend's arms and fell down hard.. That night, the female Guinea woke us up with some very strange sounds. She sounded like a chirping bird.
Since then, she sometimes repeats these sounds (most often at night, but not always). Mostly, we are puzzled as to why as there is often no apparent reason for her sounds. Also, when she makes the sounds, she appears to be in a trance-like state, making no movements at all.
Looking for the answer online I found many discussions on the subject like this one or this one. Mostly, the sounds (and the often mentioned trance like behavior) appear to be interpreted as either (1) alarm sounds, (2) loneliness sounds or (3) happiness sounds.
There are also recordings of it one Youtube, like this one.
What I was wondering:
Does anybody know about some actual research that has been committed on this subject? If so, what were the results?
I'm just so very curious to find out!

Today's night my guinea pig did the same chirping sound, as you explained early. I got really scared, i did not know what to do. I almost felt like his going to die. Then when i stept out of my bed, those chirping noises magicaly stoped. So i got to him, turned on the light, and i tried to make him calm. I got to bed, and after 2 minutes or so, i heared the same exact sound, repeating over and over again. It really sounds like a bird or fire alarm. Now i decided to move my guinea pig in my room, so if he does it, i could easely calm him down. Now i'll get some good sleep. By the way, as soon a

I found this question very interesting so I did some research. Here's a brief summary of what I've found:
Researchers have found that there are 11 different call types. Some of these include a "sharp alarm cry", "sociable clucking", chutter, whining, purring etc. Using body position and behaviour, researchers attempted to associate these vocalizations with behaviour. Some vocalizations had no apparent associated action including what researchers designated the "chirrup" ( I think this is similar to what your guinea pig might have emitted.)
For more information you can read the results section of this paper by Berryman. You can find a full description of each of the 11 calls and their assumed cause or purpose. Some involve social interaction, reproduction, and distress. Much of the research regarding Guinea pig vocalization involves communication and response between mothers and pups.
In short, it seems as though this chirping behaviour your Guinea pig is exhibiting is normal, but not of any known cause.

Plus one and labeled as solved for the extensive reply and link to comitted research. Sadly though that they have not yet figured out it's cause, as I am almost sure the sound does indeed have a function.. almost all the sounds they make have a quite clear purpose, as you'll notice if you ever have them as pets. But with this sound, the entire behaviour changes (the trance thing). I even read somewhere that someone who had a chirping pig noticed how all her other pigs would group up and get into the trance state all together to become hyperactive afterwards.. mysterious sounds they remain...

Yes, a lot of vocalization seems to involve communication with offspring. With your Guinea pig, it could be a misdirected maternal instinct. The paper I cited was from 1975, so it is possible that other researchers have suggested a reason or cause for the vocalization though I did quite an extensive search on scholar.google.com and couldn't find anything else!

Hmm, maybe there is also confusion on what sound should/could be labeled as a chirp with Guinea Pigs. In this more recent article (2013) the chirp is described as: Chirp is an isolated brief acoustic impulse with a harmonic structure accompanying the calming of an animal in comfortable conditions. But this does not at all seem similar to the singing bird like sounds that our own Guinea makes at night (and some others as well as I read on Internet forums) that sometimes can go on for up to 20 minutes or more..


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What is the average age of my flesh and my bone?
A study reported in the New York Times on August 2, 2005, claims that the average age of all cells in a middle age human is 7-10 years. This was based on new techniques at the time that allowed for very precise measurements of carbon-14 in human DNA.
My question is partly regarding whether or not this claim has been confirmed, changed or improved upon in the 12-odd years since the original study.
Mainly however, my question is simply: What is the average age of the flesh, bone and body as a whole of a middle-aged human?


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What kind of spider is this? Brown with white spots

It was found in Houston, Texas, but I've never seen one before. Does anyone know what it is?

Why did you have to kill it by burning it? Couldn't you just step on it? Or, even better, just leave it alone?

Your pictures are really small. Don't you have better ones? 2) You displayed twice the same picture. Why? 3) The fact that you were scared of this little creature and decided to offer it one of the worst possible death is up to your own standards in ethics but it is certainly not a necessary information to ID this species.

The fact that you killed it is irrelevant and apparently unsettling to some people. Stop putting it back in your question.

Sub-adult tropical orb weaver spider.  "Its range is largely circum-Caribbean, occurring in Florida, Louisiana, and Texas along the Gulf Coast of the United States."

Harmless to humans and considered beneficial.

Bites of this species are not known to cause serious effects to humans. ... The web probably catches many moths and other night flying insects; these spiders may be particularly beneficial along woodland borders of field agroecosystems and within orchards.


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Splicing and “the dominance of RNA-world”
This is a paragraph from my textbook.

The significance of such complexities is now beginning to be
  understood. The split-gene arrangements represent probably an ancient
  feature of the genome. The presence of introns is reminiscent of antiquity,
  and the process of splicing represents the dominance of RNA-world. In
  recent times, the understanding of RNA and RNA-dependent processes
  in the living system have assumed more importance.

NCERT XII (pg. 111)
I am unable to understand the above sentence in bold. Can anybody explain. Thanks

I have changed the title so it is more general. This will allow better indexing and make it more likely that it is noticed by people searching the terms splicing and RNA world for general information, rather than wishing to interpret the same phrase in this book.

This is a badly-worded phrase that means nothing in the context of the paragraph in which it occurs. There is no way the reader could be expected to understand it from this awful book on its own. Normally I would not think it the role of this site to remedy deficiencies in text books. However, as this involves some interesting questions I will try to read the author’s mind.
The author probably means something like:

“splicing is a relic of the RNA world”

…although a more measured statement would be:

“the existence of self-splicing supports the idea that the current DNA/protein world was preceded by an RNA world”

The author’s use of the word “predominance” is just incorrect English. (Sloppiness or deficient vocabulary.)
An RNA world?
So what is all this about an ‘RNA world’? The author refers to this on p. 104. He states as a categorical fact what it is important to realize is only a theory:

RNA was the first genetic material…RNA used to act as a genetic material as well as a catalyst…

Why is splicing relevant to this? Some types of splicing are catalysed by the RNA itself — self-splicing — an example of an RNA enzyme (ribozyme). From the existence of these and other ribozymes it is argued that originally all enzymes may have been ribozymes, and protein enzymes only developed later, taking over most, but not all enzyme functions.
It is important to realize that RNA preceding DNA, and the first enzymes being RNA rather than protein, are two independent ideas. Although both these ideas are widely held, and I personally tend to favour them, certain scientists have argued strongly against them, as discussed by Harold S Bernhardt.

Thnx for your answer. I have accepted it. Can u plz explain that how the “the existence of self-splicing supports the idea that the current DNA/protein world was preceded by an RNA world”

@San — As I wrote, the RNA World idea postulates a stage before protein enzymes in which all enzymes were RNA. (Among other things this addresses the chicken/egg problem of protein synthesis discussed in https://biology.stackexchange.com/questions/43111/was-there-originally-a-non-ribosomal-way-of-synthesizing-proteins/43792#43792.) At a basic level, any contemporary RNA enzyme demonstrates that such a world of non-protein enzymes might have been possible. For more details you should look at the references I have included in my answer.


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Excessive sweating in dry heat
It's pre-monsoon season here in India. The temperatures in the Northwest of the country really take a spike around mid April. Apparently the heatwave-like conditions seem to have announced themselves quite early this year. The mercury is at 42°C for most of this past week.
I'm new to this region and even though the relative humidity is quite low, such weather conditions prove unbearable to me. A few minutes walk down the Avenue and I start to sweat in bucket loads.  However, I find locals here don't sweat too much even in this hell of a weather. They say this weather is still bearable and that the monsoon phase proves to be the worst.
Having witnessed monsoon in other parts of the country I find favorable weather conditions prevailing at that time. The rain brings down the temperature and the air seems to get cooler. Most people here and elsewhere in the world would disagree with me on that. They say humidity is the worst and than dry heat can be combated by drinking enough fluids. I also see people sweating more in humid conditions compared to in temperatures of 42°C. The opposite applies to me. I barely break a sweat in temperatures of mid 30s despite there being high humidity.
What is this anomaly? Is there evidence that some bodies are just meant to excel in certain weather conditions while finding life difficult in others? Kindly help me understand the science behind it all.

It's not so much that you sweat more in humid conditions, but that the sweat doesn't evaporate as fast.  Beyond that, I'd say you have two kinds of adaptation going on.  First is personal adaptation: since you're new to the region, your body hasn't gotten used to the heat yet.  (Especially if you spend a significant amount time in air conditioned buildings.)  Second is genetic adaption: the locals and their ancestors have spent millenia in that climate.  People who couldn't handle it either left or died.

My assumption is that if you're sweating excessively, you could also be suffering from a condition called hyperhidrosis. This is a condition whereby your hands and feet sweat excessively. I would suggest that you try looking into using a solution like an iontophoresis machine to be able to treat this condition. I too have suffered from sweaty hands for a long time, and after trying different options, I found that using an iontophoresis machine provided me with the best results.

Suggesting the OP to use a device to combat a condition based on your assumption would be a bad way to answer this question.

I'm pretty sure I don't suffer from hyperhidrosis. I don't sweat excessively unless I'm working out or being physically active. I figured my choice of clothes had something to do with my woes against dry heat. Simply tricks such as walking in shade and walking at a slow pace as opposed to a brisk one, latter being inherent in nature, have made a huge difference.

Another thing I noticed about my body is that it likes being wet. As long as I have water on my skin, my body stays cool. However, the moment water has dried off, the body gets hot. I notice this after the bath. My understanding is that there's nothing unusual about it. But this phenomenon absolutely plays to my advantage in humid weather, where the sweat doesn't evaporate. With sweat on the skin, acting almost like water, my body doesn't warm up too much.


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What is the name of this tree with yellow flowers?
Location is South India,
Tree is very large, but leaves are very small.

Image: https://i.stack.imgur.com/CsSKp.jpg

For next time (because it has already been answered), it would be good to have a close-up on the flowers.

Looks like this one: https://en.wikipedia.org/wiki/Peltophorum_pterocarpum
Peltophorum pterocarpum or the Copperpod

How did you find it? which site helped you to identify this tree?

Honestly? https://en.wikipedia.org/wiki/Trees_of_India This right here.

@MalharKhushu OP's specimen almost certainly Peltophorum pterocarpum ; but the picture you attached, looks slightly different, with drooping inflorescence, and leaflets are quite different.

Sorry, @AlwaysConfused should I find a new picture?

@MalharKhushu that might be better. You would find more typical image on wikipedia and Wikimedia such as this and this . If you have trouble with image resize, feel free to let me know; I'll made smaller version for you.

I don't know the image attached currently to your answer is really a different species or just another form-variation of P. pterocarpum; but it is looking much atypical than P. pterocarpum.

@AlwaysConfused is this better?

@MalharKhushu Seems better


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What bird is this?

Location: Urban area near the Western Ghats, Kerala, South India.
Date: 20th April, 2017
Current Climate: Hot and humid. Occasional rains.
Brief Description:
Not large, about the size of a house sparrow. Didn't make any characteristic sound/chirping during the period of observation. Pointed,slightly curved, thin beak. Probably feeds on insects, grain, nuts. Has a black crest atop its head, similar to that of a woodpecker. Appears to have an off-white or pale yellow "mouth" (couldn't get a picture of that, sorry). Chin and throat have white feathers. Foot and legs appear dark gray, if not black. Possesses conspicuous red infraorbital patches (of feathers?) below each eye.
Additional Information:
The locality is often frequented by feral pigeons. However, this particular bird made its appearance when there were no pigeons in sight.

That is a red whiskered bulbul.

(image from the Wikipedia article)
The crest isn't as prominent in your pictures - maybe it has just been to the barbers.


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Help identify this mite?
I saw a decimal-sized dot walking on my hand. I wanted to know what this is, so I got it onto some paper and sandwiched below a piece of clear tape so I could keep it in place and photograph it. However it's so small that even with my camera lens almost touching the specimen, I can't get a great photo. It's small, about 0.8mm long, beige or gray or brown with a pattern on the back. It's a little smooshed from the tape so it's hard to tell if it has 6 or 8 legs and is an insect or an arachnid. But hopefully based on the shape, size, and pattern it can be identified.
Location is southern California.

Update: I now believe this to be a rat mite or bird mite. I'll include some additional photos that were better quality (photos were taken with a close-focus camera, mites were on printer paper underneath Scotch tape, back-lit by an LED light):

@theforestecologist I updated it again with a few more photos.

Related: Bug Identification: Tiny Bugs, Tiny white very hard cell bug! Please help to identify!

This appears to be a bird mite (or possibly rat mite) in the genus Ornithonyssus of the parasitic family Macronyssidae.

 Credit: user Aewills on bugguide.com
Distinguishing between species is difficult.
In fact, according to idtools.org, identification of Mesostigmata to family or lower can usually only be accomplished if the specimen is an adult female.
Blaine Mathison mentions the following features useful for identifying these mites to lower taxonomic levels under magnification [source: bugguide.com]:

chelicerae shape
dorsal plate breadth and degree of dorsal coverage
spiracle present between legs
genitoventral plate width
sternal plate shape and presence of setae

You can find existing answers to posts about bird mites on Biology.Stackexchange below:

Bug Identification: Tiny Bugs
Tiny white very hard cell bug! Please help to identify!

It could be a tick nymph. Difficult to tell as you can't see the beak and the front legs very well. Check out this tick identification site:
http://www.tickencounter.org/tick_identification/tick_species
Looks most like the dog tick maybe?

Thanks. Actually it turned out to probably be a mite, probably a rat mite. I found many more which appeared to be coming from the attic where we have had rats, and when I took more macros they did appear to look like rat or bird mites. I just never got around to updating this with the new info and photos.