What causes the surge in luteinizing hormone just prior to ovulation? |
- What causes the surge in luteinizing hormone just prior to ovulation?
- Is there actually a solution to the twin paradox?
- How do bees know their way back home?
- On the complex number plane, why are coordinates expressed as a value, like 2i+1, and not as an ordered pair, like (1, 2i)? Or do they represent something other than corrdinates?
- Are birds monophyletic?
- What makes mining asteroids so potentially profitable?
- Did insects evolve from crustaceans?
- Why was carbon-dioxide used in the Chicago Pile 1?
- When elements and/or compounds freeze, do the molecules arrange themselves in a hexagonal array, or is only H20 only like that? If elements and/or compounds do not form hexagonal arrays when frozen, what kind of structure do they form?
- Has a CPU ever been designed for a specific programming language ?
- What makes sunset red?
- Does background radiation play any role in genetic mutation, ageing, or development of cancer?
- How are we able to predict trajectories based only on feeling?
- So we know that black holes exist, does that mean the theoretical white hole exists also?
- If a computer is based on transistors that go off and on for a 0 or 1 how do computers do basic math functions(add,subtract,multiply,divide)?
- Do cars in higher elevations get better gas mileage?
- Why doesn't the well ordering principle apply to nonnegative rationals, or negative integers?
| What causes the surge in luteinizing hormone just prior to ovulation? Posted: 16 Jun 2019 12:12 AM PDT I have read a few physiology textbooks that were published a few years ago, and I have not gotten anything concrete. I read from the 9th edition (latest) of Sherwood Physiology, which states that there are two sets of kiss1 neurons in the hypothalamus. According to the text, negative feedback involves low concentrations of estrogen inhibiting the kiss1 neurons in the arcuate nucleus whereas positive feedback involves high concentrations of estrogen stimulating the kiss1 neurons in the anteroventral periventricular nucleus. Kiss1 neurons secrete kisspeptin, which act on GnRH-secreting cells in the hypothalamus. However, the 13th edition (latest) of Guyton-Hall says that "the cause of this abrupt surge in LH secretion is not known". It states two possible explanations. The first one is the one that Sherwood gives - about how estrogen has a "peculiar positive feedback effect" of stimulating pituitary secretion of LH, which is in "sharp contrast to the normal negative feedback effect of estrogen that occurs during the remainder of the female monthly cycle." The second explanation Guyton-Hall suggests is that the granulosa cells begin to secrete a small but increasing amounts of progesterone a day or so before the LH surge, and it has been suggested that this secretion might be the factor that stimulates the excess Lh secretion. My main question is: since the publication of these textbooks, have we learnt anything new or is this still something that we are not sure of? edit1: Added some info for clarification. [link] [comments]  |
| Is there actually a solution to the twin paradox? Posted: 16 Jun 2019 06:50 AM PDT All the ones I've come across assume that the twin on the rocket is the one changing velocity, (accelerating) which breaks the symmetry, causing him to come back younger. The whole point of relativity is that there are no preferred frames of motion. (each twin would have the same right to claim that it's the other one who is accelerating) In general relativity it's not only the apple that falls to the earth, but the earth that falls to the apple. Both points of view are equally valid. To have it simplified, substitute the twins with two objects in empty space that break apart and come back together again. There is nothing else in that universe for these objects to move relative to so what's to decide if one object's acceleration was any more real than the other? [link] [comments]  |
| How do bees know their way back home? Posted: 15 Jun 2019 09:41 PM PDT I was watching my garden this morning and I saw some bees buzzing around. I followed some of them and found out that they visit many flowers in a way that appears very random. How can they know their way back home? [link] [comments]  |
| Posted: 15 Jun 2019 07:18 PM PDT |
| Posted: 16 Jun 2019 07:43 AM PDT Obviously at some point all birds share a common ancestor, but I'm wondering if that family tree also contains dinosaurs that we do not consider to be birds. Essentially, is the only truly defining trait of the "avian dinosaurs" that they were the ones that survived to the present, or are they are clearly distinct taxonomic group? [link] [comments]  |
| What makes mining asteroids so potentially profitable? Posted: 15 Jun 2019 07:12 PM PDT To add to the question, what rocks/ore/minerals within the asteroid are so valuable and who on earth (literally!) would pay big bucks for it? [link] [comments]  |
| Did insects evolve from crustaceans? Posted: 15 Jun 2019 08:47 AM PDT |
| Why was carbon-dioxide used in the Chicago Pile 1? Posted: 15 Jun 2019 09:35 PM PDT I read that the Chicago Pile 1 was encased by a large balloon which was then filled with carbon-dioxide. What would this accomplish? [link] [comments]  |
| Posted: 15 Jun 2019 05:16 PM PDT |
| Has a CPU ever been designed for a specific programming language ? Posted: 15 Jun 2019 03:25 PM PDT |
| Posted: 15 Jun 2019 06:42 PM PDT Sometimes sunsets tend to more more red-ish. From where I live, most of the time it is not. The sky is dark blue. On the other hand, on other times, a big chunk of the sky would be red. Why is that? [link] [comments]  |
| Does background radiation play any role in genetic mutation, ageing, or development of cancer? Posted: 15 Jun 2019 03:23 PM PDT |
| How are we able to predict trajectories based only on feeling? Posted: 15 Jun 2019 05:25 AM PDT How are we able to "calculate"without actively using any calculations? [link] [comments]  |
| So we know that black holes exist, does that mean the theoretical white hole exists also? Posted: 15 Jun 2019 07:52 PM PDT |
| Posted: 15 Jun 2019 02:50 PM PDT |
| Do cars in higher elevations get better gas mileage? Posted: 15 Jun 2019 05:25 AM PDT I'd think so, because there's less air to create drag, but then again, maybe less/thinner air affects the engine somehow. [link] [comments]  |
| Why doesn't the well ordering principle apply to nonnegative rationals, or negative integers? Posted: 15 Jun 2019 08:08 AM PDT The well ordering principle is that every nonempty set of nonnegative integers has a least element. For a set of nonnegative rationals, shouldn't the least element be zero, or whatever number is closest to zero? For a set of negative integers, shouldn't the least element be the negative number with the largest magnitude? Why can't the well ordering principle apply to these sets? [link] [comments]  |
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