genetics - How do circulating androgens contribute to higher rates of hirsuteness in some women?

I was reading up on ethnic groups in which the women are naturally more hirsute (such as South Asian women) in the context of evolving standards of beauty. I came across this statement on a forum:

Hirsutism is much more common in South Asian women (particularly North Indians such as Punjabi Sikhs) asymptomatically because they tend to have higher levels of circulating androgens than your typical [North or Western European ethnic group]. This is also true of Eastern European women to an extent.

Per Wikipedia, I learned:

Circulating levels of androgens can influence human behavior because some neurons are sensitive to steroid hormones. Androgen levels have been implicated in the regulation of human aggression and libido. Indeed, androgens are capable of altering the structure of the brain in several species, including mice, rats, and primates, producing sex differences.

So: do circulating androgens trigger higher testosterone production in some women? Is this what yields higher instances of "hirsutism" among certain populations? How are some women more prone to this than others? (That is, per the forum post, why are South Asian women more likely to have this than Western European women?)

neuroscience - The Operation of tuning in the S1 layer of ventral model

According to my previous question in ventral Stream pathway and architecture, I want now to get a brief example about how the S1 layer is constructed. In other words, how all the simple units are tuned with the gaussian-Like tuning (for example). I am only interested to get such a cartoon example in step by step how this operation can be achieved in given of inputs (which inputs? and what we mean about these inputs?) in order to obtain the tuned simple units.

We all know that each simple unit is obtained after a tuning operation around their inputs (Subunits) in order to select an optimal output which corresponds to the preferred orientation for such a simple unit.

Moreover, I know that the S1 layer units perform a convolution on regions of the raw input image using gabor filters at different orientations and sizes. The entire population of S1 units represents a convolution map of Gabor filters of different sizes and orientations with the entire raw image (really I didn't understand this point) you can read the subsection 2.2 in this article

The image below contains the image to be recognized by the brain and some simple units obtained after the tuning operation. So what I want is to obtain a brief example which can include the details (step by step) of how the operation of tuning can be achieved.

i didn't understand well the concept. That's why i need a real example with a specific image which can contains all the steps described in my attached image (step by step) because i still don't understand what we mean about inputs x, etc.
So please if anyone can give me a real example with a specific image which can respond briefly to this attached image

human biology - Can a color-deficient person be made to visualize the missing colors?

It is a very interesting question and I did some efforts to investigate the literature on this topic, but yet I don't have a definitive answer for you. But let's start from the beginning.

First of all, the reason for color deficiency can be not only lack (rare) or impairment (more often) of certain types of color-perceiving cells (cones) in retina, but also brain injures: the central color blindness can develop after head trauma or as a result of some neurodegenerative deceases, like Parkinson's decease. In case of brain origin of the color blindness it is usually the complete color blindness (no color is percieved), whereas congenical primary color blindness (receptor-based) is usually just the unability to distinguish one or two colors, whereas the rest can be more or less separated.

I searched Pubmed for the literature on the topic and found a recent PNAS paper about the simulation of primary and secondary visual cortex on humans using intracranial electrodes. As they describe their results (bold font by me):

When percepts were elicited from late areas, subjects reported that
they were simple shapes and colors....

But the paper investigated only healthy humans, no color impaired subjects were used for the tests, so cannot conclude from here whether we can elicit the perception of the color the person is incapable to see with the eyes using these stimulations.

I took this paper as the starting point and did some reference research, looking for the paper referenced there and for newer publications referencing this one: PNAS is one of the top journals in this area with very high impact factor and if there were a publication about brain stimulation and color blindness I would have definitely identified it.

During my investigations I came accross a series of interesting articles devoted to "cortical visual neuroprosthesis for the blind" (read this paper^<1> from 2005 for review on this topic), but this is the treatment of conventional blindness, not the color blindness. There was no intersection in keywords or titles for color blindness and brain stimulation, both in the referenced articles and in the complete article database.

So, I would suggest that you address some talented experimentalist with your question and maybe one day, who knows, we will read your name under the Nature article dedicated to the novel way to cure color blindness.

---

^<1> -- unfortunately not available publicly for free, I am sorry.

gene expression - What is the best way to express two proteins in a mammalian cell?

You can use a bidirectional promoter. The problem that you mentioned about proteins not expressed in same level happens because of competition for polymerase. But there are well optimized parts and also commercially available vectors that work fine.

You can clone genes in a serial order. It won't be a problem. Just leave a 100bp linker after the polyA signal of previous gene. If your cassette becomes too huge, then insertion becomes slightly difficult. That's why people use IRES or TA-peptides, etc.

Retroviral based insertions work quite decently, but you can't control copy number variation between different cells.

You can use two different promoters. The dynamics will depend on the promoter strength and concentration of inducer.

philosophy of science - How to define "evolution"?

Theoretical biology spans multiple disciplines and the unaccompanied term evolution is defined differently in each:

As such chemical evolution is different from time evolution in physics and many other systems in theoretical biology that "evolve". These do play a role in theoretical biology.

Also, what standard answer to evolution in the field of theoretical biology are you referring to?

I recall learning that an allele as a special[:species:] gene variant, is defined as such as being present in at least one percent of the population. That definition has broadened meanwhile. A definition that has broadened.

Point in case, I don't believe there to be an evolutionary master-framework to (yet) exist, along the lines of desires for a Theory of Everything in physics.

On the other hand, as soon as you cross the boundaries of biological evolution, like let's say in the most primitive of living, biological entities, you are bound to cross over to cultural evolution as well. ( I am no expert on the subject, there are probably other intermittent steps as well). Synergistic effects in the process of evolution may even be considered in Quorum Sensing's most favorite model: Vibrio fischeri.

A simple search on the subject instantly yielded me:

"Evolution of alkaline phosphatase in marine species of Vibrio". J Bacteriol....

In other words: molecular evolution, as being part of the many evolutiony research focuses.

The idea and gross effects of Darwinian evolution are often rather straightforward at first glance. All the little details, that have to be accounted for -with scientific rigor-, as science itself is evolving, are probably where the team-work starts, as do the discussion.

So the only fixture you can count on is team in science.

The introduction to the evolutionary topic at hand, that you would use in an abstract or introduction would depend on the scientific sub-discipline, and would likely already be readily available through peer-publication.

bioinformatics - What is the difference between local and global sequence alignments?

Global alignment is when you take the entirety of both sequences into consideration when finding alignments, whereas in local you may only take a small portion into account. This sounds confusing so here an example:

Lets say you have a large reference, maybe 2000 bp. And you have a sequence, which is about 100 bp. Lets say that the reference contains the sequence almost exactly. If you did a local alignment, you would have a very good match. But if you did a global alignment, it may not match. Instead, it may look for matches throughout the entire reference, so youd end up with an alignment with many large gaps. It does not matter that it matches near perfectly at one particular region on the reference, because its looking for matches globally (ie throughout the reference).

If you have a really good match it may not matter what type of alignment you use. But when you have mismatches and such it starts to get important. This is because of the scoring algorithms used. In the example above lets say that there is a 100bp region in the reference that matches your 100bp sequence with 85% accuracy. In local alignment its very likely it will align there. Now lets say that the first 30 bp of your sequence matches a region in the beginning of the reference 95%, and the next 30bp matches a region in the middle of the reference 85%, and the final 40bp matches a region at the end of the reference about 90%. In global alignment the best match is the gapped alignment, whereas in local alignment the ungapped alignment would be best. I think in general gap penalties are less in global alignments, but Im not really an expert on the scoring algorithms.

What you want to use depends on what you are doing. If you think your sequence is a subsequence of the reference, do a local alignment. But if you think your entire sequence should match your entire reference, you would do a global alignment.

botany - How do trees lift water higher than 10 meters?

The atmosphere pressure is 10 meters of water (approx). This means that it is impossible to lift water higher than 10 meters with vacuum or сapillary action (on Earth, under normal conditions).

There are trees higher than 10 meters.

How do they lift water to their tops?

UPDATE

In other words: how cohesion-tension theory can be true if it apparently contradicts the laws of physics?

UPDATE 2

Atmospheric pressure helps to rise the water, not resists rising. What is resisting is water weight. When water column is 10 meters high, then atmospheric pressure can't help anymore.

Any adhesion/cohesion mechanism can't help here too, because it acts only in thin molecular layer. To transfer action force further the pressure is required, which is insufficient at 10 meters.

UPDATE 3

If we had capillary small enough to rise water to 10 meters and then we will build smaller capillary which we expect will rise water higher, we will fail. Water column will break and does not climb higher than 10 meters.

Menisci acts like small piston and can't help rising water higher than 10 meters.

UPDATE 4

Common pressure distribution in capillary is follows:

$P_0$ is atmospheric pressure. As you see, right under menisci, the pressure is lowered by $2 \sigma / R$ where $R$ is the radius of menisci and $\sigma$ is surface tension. The entire term is called "Laplace pressure". As you see, it can't supersede atmospheric pressure, because water continuity will be broken in the case.

I.e. no any menisci can rise water higher than 10 meters.

The existence of higher trees PROVES that there are some other significant mechanisms, not adhesion/cohesion, not capillary.

UPDATE 5

Current version, as I understood it, is based on a declaration, that a water, if put into thin capillary, can behave like a solid body. Particularly, it can resist tension up to minus 15 atmospheres.

This is a tensile strength of concrete, so I don't believe that without additional proofs.

I think it is just not hard to make thin tube, put water into it and check, how high it can climb.

Was it done ever?