Recent comments in /f/askscience

zumiaq t1_jcpf1ql wrote

Reply to How does immunity to larger internal parasites such as worms work? by OryuSatellite

I can't say for sheep specifically, but most immune response is targeted at initial infection with the parasite.

In human helminthiasis, the main defenders are T-lymphocytes and eosinophils. They produce a ton of cytokines that are mainly focused on damaging/inhibiting eggs or young, very small parasites during initial infection. B cells and antibodies may be involved, but--once again--antibodies are not going to have substantive effects on the type of large intestinal worms you are talking about.

While I'm sure the host body has some immune tricks to tackle adult helminths, and others can hopefully chime in with them, by the time you have a chronic infection with large worms the parasite-host relationship is pretty established. Many helminths produce immunomodulating compounds which actively tell the immune system to not fight the worm, and, for the most part, the host is now a host and spontaneous recovery without some sort of medical intervention is unlikely.

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KauaiCat t1_jcp2xwe wrote

Reply to How do greenhouses actually work? by _Dnikeb

A "greenhouse" gas or "greenhouse" effect really has nothing to do with a literal greenhouse.

A molecule can only absorb IR if its vibrational modes cause a change in its dipole moment. No matter how you configure the two nitrogens of N2, it will always have zero dipole. Therefore, N2 is not a greenhouse gas, but if you bend a CO2 molecule, it will have a net dipole.

This means it will absorb IR photons of certain wavelengths and become excited where the wavelengths are associated with vibrational modes of the molecules.

Once a greenhouse gas has absorbed an IR photon it could: transfer the photon's energy to another gas molecule during a collision, relax and re-emit the photon, or lose the energy by combination of collision and emisssion which will result in emission of a photon with a different wavelength than the original photon.

As greenhouse gas concentration increases, re-emitted photons are more likely to be absorbed by another molecule, providing resistance to the energy leaving the earth.

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loki130 t1_jcoq0lp wrote

Reply to comment by EarthHuman0exe in How do greenhouses actually work? by _Dnikeb

Those are the most important in Earth's atmosphere, but methane, ozone, and NO2 also contribute, and there are numerous other gasses that could act as greenhouse gasses (and some cases where certain combinations of gasses can have a stronger greenhouse effect than either alone).

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Broad-Turnover6945 t1_jcoitf1 wrote

Reply to How does the body excrete bacteria and infections? by leinard97

Great question! Physician here. The body has a really neat way of cleaning up infections and a multitude of pathways to achieve it. Typically, once your body recognizes a foreign pathogen and attacks it (either by antibody’s or special cells called T-Cells) it will pick up said offender from tissue and deliver it to the lymphatic system. This a system composed of highways that parallel veins/arteries. Within the lymphatic system are lymph nodes, this is where your body will “sound the alarm” and help to amplify the specific defense against that pathogen. It will break down the bacteria or virus that is encountered and essentially ultimately break down its components to sub unit level where their parts can be recycled.

In the blood, a similar process but with the reticuloendothelial system, one that consists of the spleen, liver, and blood that involve clearing bacteria from the system

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elegance78 t1_jcoaeqz wrote

Reply to comment by Jarlentium in How do greenhouses actually work? by _Dnikeb

https://youtu.be/oqu5DjzOBF8 For the first time I actually understood what earth scale "greenhouse" effect is. The stupid name does so much damage.

Actual greenhouses - infrared escapes through the glass easily and heat losses are very high at night. To the extent that growers measure this with pyrgeo sensors and take actions to prevent it (closing thermal screens so that plants "see" the warm screen material instead of the -50C clear night sky.

They work by trapping warmed air (warmed either by sun or warmed by hot water pipes). Actual trapping works by greatly limiting air exchange. In fact, there is not enough air exchange capacity to even out inside temperature of an empty greenhouse and outside temperature on warm summer day. We rely on the moisture transpired by the plants to cool down the greenhouse. To achieve this we limit the air exchange - it may be 40C outside but it can be 31-33C inside.

We also enrich air with co2 to 1000ppm. Only way this affects the inside temperature is the effect it has on plant transpiration.

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GulliblePlantain6572 t1_jco58ix wrote

Reply to comment by Greyswandir in What decides which wavelength to reflect and which one to be absorbed in an object? by TheSimpleHumans

Thank you for elaborating! So the color of something is mainly based on what color of those that we can see that is absorbed least, pretty intuitive. I'm assuming there are also times when we would have to take combinations into account if there are a few wavelengths that are not absorbed much? Also I was reading a bit more about complementary colors and I think the premise is that 2 complementary colors would combine to form white. So I guess the idea is that if one color is absorbed much more than others, we would interpret the remaining light as the complementary color to the one that was absorbed, since the light was initially white and lost a lot of light of a specific color.

And 1 more question, does an emission spectrum for some molecule give essentially the same information as an absorption spectrum?

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