Hot answers tagged

33

Off the top of head as a medical professional I can imagine the following mechanisms (everything is just speculative reasoning): Insects don't have blood. Instead, they have hemolymph whose primary role is not oxygen transport (they have an additional tracheal system for this purpose), but rather that of nutrients. Thus they don't need (and don't have) an ...


15

My friend Brightblades is right in one thing. It seems your teacher was working off a caricature of what the theory of evolution actually says. First of all, you should read Sklivvz's excellent answer at this question. Now to address the elephant in the room, the accident at Chernobyl only happened in 1986. That was only 26 years ago. In that timeframe, ...


13

Studies of Deinococcus radiodurans, the most radioactively tolerant microorganism we know, show that it has many genes for DNA repair. In the case of the cockroach, I would assume that in addition to repairing genes, and maybe some antioxidants produced in the cells to quench free radicals produced by radiation, the fact that the roaches lay many, many ...


8

I think you have a fundamental misunderstanding of the chemical reactions involved in radiation therapy. Neither photon based or proton based therapies "create electrons", but they do cause ionization by adding enough energy to existing electrons around atoms so that the electron is ejected from the atom, creating an ion or free radical, which can then ...


6

Radiation poisoning causes mutations in DNA that affect normal cell function, often causing them to die. Cells normally have a number of repair mechanisms but if the damage is too great they won't be able to do so. In particular, cells that are dividing quickly will not have time to repair their DNA before division and so die far quicker than other cells. ...


5

No, one can't confirm age by carbon dating. That doesn't mean we can't make a decent guess by other methods. There is an interesting case of a 33 year old Texas woman who enrolled in 10th grade in Texas. She said she had no transcripts because she had been homeschooled. She looked like a teenager and acted like a one too. She even fooled her new 23 year old ...


4

It's actually because of the greater risk "from breast, ovarian, and uterine cancers" (article). There's a more scientific write-up here, and while I don't have access the abstract implies that a more rigorous update of the exposure criteria upheld sex differences. From a more terrestrial perspective, The Nuclear Information and Resource Service (nirs.org) ...


4

The type of radiation is quite different in a medical X-ray vs. an airport scanner. Medical X-rays are high frequency (beyond ultraviolet) radiation, typically on a wavelength of a few angstroms. While I would emphasize that @Ram is right to point out that there is not very much radiation in a medical X-ray since electronic detectors have been in place ...


4

According to Paul Stamets, Gomphidius glutinosus is especially well suited to collecting Cesium-137: G. glutinosus has been reported to absorb – via the mycelium – and concentrate radioactive Cesium 137 more than 10,000-fold over ambient background levels. That article and Stamets' book Mycelium Running have more details on other species.


4

Addition to the previous answer First you need to understand how radiation causes cellular damage. EM waves like γ-rays, X-rays and high-energy UV (in certain molecules even visible light) can knock out the electrons from the atom and create an ion and free radicals by breaking chemical bonds. This term — ionizing radiation is not used for low energy UV ...


4

Yes, this can happen, although the risk is low. The problem is that some tumors need to be irradiated since the cannot be operated (this is true for some brain tumors). Here the radiation therapy is the therapy of choice. The effect of the therapy is that the tumor cells get a high radiation dose which either kills them or drives them into apoptosis. The ...


4

Microwave ovens can indeed kill bacteria in food by heating them to high temperatures. For example, this article found that microwave heating could kill all of the Salmonella bacteria in a chicken thigh sample: The effect of microwave heating on Salmonella Enteritidis inoculated on fresh chicken was investigated using a microwave oven (800 w) to ...


4

Yup. Radiation induced secondary cancers exist and vary in their site of incidence and risk of incidence based on the site of treatment. In breast cancers treated with radiation, for example , there is upto a 3 fold increase in relative risk relative to the general population for leukaemias within five years and 1.5 times the relative risk for secondary lung ...


3

This is an interesting - and highly debated question. Generally there are two completely different directions of thinking when talking about dangerous substances (this applies to dangerous chemicals as well): The linear no-threshold model (LNT). The hormesis model, in our case the model of radiation hormesis. Summarizing the models the LNT model says ...


3

In the most technical sense, yes. In a practical sense, no. Average background radiation dose from food and water sources is ~.3 mSv according to the UN. Given that it takes 1 full Sv to increase cancer risk by ~5-6%, it seems unlikely that, under normal conditions, variability in consumption of water will change risk in a significant fashion. Now, when ...


3

How far could we go towards engineering a space-durable human species? I think this question is likely to get closed as off-topic. It is extremely hypothetical and would be a better fit on WorldBuilding.SE. But here is my messy attempt to answer this question. Assumptions So, I guess in your question, you assume that we know everything about how our ...


3

Great question. It is unfortunate that more people don't understand what "radiation" is and how it affects biology. Firstly, you must distinguish between ionizing radiation and non-ionizing radiation. Wikipedia describes the former rather well: Ionizing (or ionising) radiation is radiation composed of particles that individually carry enough kinetic ...


3

Good question, but I'm not sure if anyone really knows the answers. The governments of Japan and the U.S. have both been very secretive at best, while an army of propagandists have made it very difficult to distinguish between truth and fiction. Any health effects are likely to be too small and gradual to make headlines. For example, suppose there was a 1% ...


2

Not sure that I understood your question correctly. The concept of "effective dose" was specially introduced to provide a mechanism for assessing the radiation detriment from partial body irradiations in terms of data derived from whole body irradiations. The effective dose is the mean absorbed dose from a uniform whole-body irradiation that results in the ...


2

The original article cited in your reference is available here for free. After a quick skim, I saw that their study was based on fossils of a single species (Moas) all taken within a 5 km radius. Thus, it's possible the fossils were preserved under relatively similar conditions, despite different preservation ages. So, it's not yet clear how their results ...


2

To grab this opportunity to sum up the comments for the C-14 dating method, including those of of @MattDMo and @canadier: Theoretically spoken - Yes we can! But only after (1) killing the person and (2) waiting a few hundred years. As carbon keeps on being recycled in a living carbon-based organism, it has to be dead first. Secondly, because the margin or ...


2

Xrays are not scans. They are one shot (or a series of a few). Say that a chest Xray (two views) doses you with .1 mSv of radiation. The dose from a standard chest CT is 7 mSv.[1] That is 70 times what a chest film gives you, not a few hundred (though that might seem like quibbling). The TL;DR answer is: no one knows for sure. Radiation (especially in ...


2

As a rule of thumb you can say that a CT scan exposes you to a higher dose than a X-ray examination, due to the different techniques. For CT scans a number of single 2D photos is processed into the 3D models. However, the dose strongly depends on what body part is examined. See a part of this table (the complete table can be found in reference 1): The ...


2

The three major nuclear incidents I can think of are the Japanese atomic bomb attacks, the Chernobyl disaster, and Fukushima disaster. Of course other nuclear incidents have occurred, but usually give much higher doses to far fewer people. Many studies have been done on the survivors from the atomic bomb attacks, and increased rates of cancer have been the ...


2

This study has received next to no media coverage. With RFR impacting so many people it makes me wonder, is this study valid? Well first of all, lets be clear: that is not a study. Its a review article, basically a paper that summarizes a series of studies published. The review itself isn't valid or invalid necessarily, it simply takes a series of papers ...


2

Is background radiation a critical component of evolution? No, it most certainly is not. The DNA replication and DNA repair mechanisms aren't perfect and errors happen without any external cause or catalyst. You could say mutations happen on their own. There are mutagens that also cause DNA damage or mutations, but they're merely affecting the DNA ...


2

Afaik. radio waves don't have enough energy to cause anything similar to the damage ionizing radiation (gamma rays) does. What it can cause is probably heat damage similar to microwave ovens. According to the United States Food and Drug Administration's Center for Devices and Radiological Health, a U.S. Federal Standard limits the amount of microwaves ...


2

In order to date the age of a tree, you have three solutions : If you can cut the tree then you can simply count the number of rings. Note that for very old trees the central rings will have rotted and you will only have a lower bound on its age. If some parts of the tree are dead, you can use radiocarbon dating to estimate the time of death with a ...


2

I'm no expert, and this is more of a physics answer rather than biology. The microwaves will not reach all of the food. This is why you get hot and cold spots. The rotating plate mitigates this to some extent, but not all of the food will receive a blast. However heat will slowly spread throughout the food. If the contaminated bits are hot enough for long ...


2

Regarding your first question, I don't know of any instance in which irradiation was used to select for a beneficial trait in humans. I italicized 'used' because I think that you could argue that naturally occurring sources of irradiation have led to the selection of traits that protect us from radiation damage. That might sound like a bit of a circular ...



Only top voted, non community-wiki answers of a minimum length are eligible