Recent comments in /f/askscience

mfb- t1_j5ild6m wrote

Reply to comment by Paracelsus19 in How do scientists calculate the size of planets and stars only by using a telescope? by BigBashyBoo

There are only a handful of stars where we can measure the angular size directly. It's far more common to measure the distance, the temperature (-> surface brightness) and apparent brightness of stars. Combined they tell us the radius of the object. That knowledge then be applied to stars too far away to measure the distance directly.

For exoplanets the brightness in images can still be useful, but the most accurate radius measurements come from transits: We measure which fraction of the starlight is blocked, so we can use the radius of the star to measure the radius of the planet.

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CaneCrumbles t1_j5iiar5 wrote

Reply to Can you scan a brain and diagnose a mental disorder? by friday_panda

The short answer is that we do not yet know. There is not yet adequate evidence to identify mental illnesses by way of MRI brains scan or PET scan. (CT scans have been replaced by MRIs for detailed brain imagining.)

There have been many small studies over the years trying to answer your question. Studies are ongoing. This article explains in non-technical terms why past studies are insufficient to come to reliable conclusions and what is happening to try to get answers to questions like yours:

https://news.yahoo.com/george-santos-married-woman-while-161923713.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_sig=AQAAAM7gyZ-j7rRPH_Mslo4CKHIALYgVLdSvFlezFrMcwSa1x9b9X10uzkzrVrSNAQdaltWrRrfFx2dfHoXncbKBAoeUlV-lsSBj6J1ZYRepJENCl8lY5DtZwI8eZQ7DVGHBX1G5xl6yRHti1_VgtSi2QH0Ol7vkN4g5TDIWifZjvjIV

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sharplydressedman t1_j5idqp7 wrote

Reply to Can you scan a brain and diagnose a mental disorder? by friday_panda

There have been decades of research trying to identify biomarkers and structural differences in individuals with neuropsychiatric diseases, using imaging (MRI, fMRI), electrical activity (EEG), or serum markers (blood work) . In major depressive disorder for example, there have been associations made with changes in the prefrontal cortex, thalamus, hypothalamus etc. as seen on MRI. However these findings are neither sensitive nor specific, so psychiatric/behavioral disorders such as MDD is still a clinical diagnosis.

I should make the distinction that there are some psychiatric diseases result from structural diseases of the brain. E.g. Alzheimer's disease, Lewy body dementia, Parkinson's disease, all have distinctive findings on MRI and can have psychiatric symptoms. However most people with psychiatric disorders do not have obvious neurological disease that can be identified with imaging.

There is a lot of research and development in the field, and there is a great effort in psychiatry to incorporate objective measurements to validate clinical findings. So our understanding of neuropsychiatric diseases is likely to change dramatically in the coming years, once we develop the tools to understand these disorders better.

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Supraspinator t1_j5i6h9n wrote

Reply to Does Mother's Rubella Vax Protect Fetus? by MaryGodfree

Short answer, yes.

Long answer: while in the womb, the mothers immune system protects the fetus. However, maternal rubella antibodies are also transmitted via the placenta to the fetus, protecting the baby after birth. The transfer increases towards the end of pregnancy, so preterm babies have lower levels, making them more vulnerable.

https://pubmed.ncbi.nlm.nih.gov/10378133/

There are other antibodies that are transferred to the fetus: measles, covid, diphtheria*, pertussis*, polio, chickenpox, and others.

*diphtheria, pertussis and tetanus requires the vaccination of the mother during pregnancy.

There is a term in German, Nestschutz - “nest protection” that refers to the passive protection babies have in their early months against some diseases. It wanes as the maternal antibodies degrade, requiring vaccines for the baby.

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sharplydressedman t1_j5i3jug wrote

Reply to Does Mother's Rubella Vax Protect Fetus? by MaryGodfree

Short answer, yes. Pregnant women are recommended to receive the MMR vaccine BEFORE pregnancy as this confers protection to the developing fetus from rubella infection. Not having immunity to rubella greatly increases the risk of Congenital Rubella Syndrome (CRS) in the fetus if the mother acquires rubella during pregnancy.

The vaccine should be administered before pregnancy since the MMR vaccine is live attenuated virus, meaning there is a small chance of developing a mild version of the disease. Although the symptoms would be mild for the mother, the risk of CRS for the fetus means it is advised to not receive the vaccine during pregnancy.

In terms of immunity, typically people who have completed the full course of MMR as a child are considered to have life-long immunity. Antibody titers do wane over time, so the only way to confirm would be to measure antibody titers with blood work.

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[deleted] t1_j5i1hqi wrote

Reply to How do we know how old viruses are? by Darth_Fatass

May I recommend this eye opening video

https://youtu.be/FmX8au0xGlY

Viruses are directly involved in our evolution. As in, you have virus dna in your dna. This is how we can tell species apart and stuff like that and see when they branched off (rough paraphrasing) viruses have been merging with our dna for a long time and scientists can use this information to map out the tree of life.

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Pikachorizo t1_j5hwq47 wrote

Reply to Does Mother's Rubella Vax Protect Fetus? by MaryGodfree

I think it depends - the pregnant women may or may not have persisting immunity against rubella.

If she does have immunity, then there is supposed to be protection from rubella, as there is a fraction of her rubella antibodies that is transferred to the fetal circulation through the placenta.

In Canada (or at least the province I'm in), it's routine to check rubella antibody levels in the a women's blood prior to or during early pregnancy, and see if they correspond to levels indicating immunity. The mother may have immunity from an actual previous exposure/infection with the virus, or from vaccination. There are certainly cases where the result has come back as no or indeterminate immunity, rather than suggestive of immunity.

Since the MMR (measles, mumps, rubella) vaccine is a live-virus vaccine, and the big reason to care about rubella in pregnancy is birth defects, the MMR vaccine is not recommended within a few weeks of starting to try and get pregnant, or during pregnancy.

All that said, I think the general recommendation is for pregnant women (immunized or not) is to avoid people with infectious diseases when possible.

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Paracelsus19 t1_j5hu5ak wrote

Reply to How do scientists calculate the size of planets and stars only by using a telescope? by BigBashyBoo

Basically, by careful observation and then doing math calculations. You measure the object's angular size as you see it in the sky and then you work out its distance based on its orbit. When you combine these two measurements, you should then be able to find the real size of an object. I hope I am explaining both correctly and clearly. There are some links below to help beak down the answer and go into further detail.

https://www.astronomynotes.com/solarsys/s2.htm

https://lonewolfonline.net/angular-size/#:~:text=Angular%20size%20refers%20to%20the,size%20of%20approximately%2030%20arcminutes.&text=The%20angular%20size%20of%20an,its%20distance%20from%20the%20observer.

https://youtu.be/Cn8Yuf0Pnsw

https://youtu.be/XF9stDi8XkM

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