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Comment Erroneous Summary (Score 4, Informative) 139

First off, the original article is open access at PLOS ONE here:

The summary statement, "The tip of the olfactory nerve, which contains the smell receptors, is the only part of the human nervous system that is continuously regenerated by stem cells", implies several things that are misleading and/or totally untrue.

The tip of the olfactory nerve is the olfactory epithelium, where the olfactory sensory receptor cells are located. The olfactory nerve travels through the cribriform plate, a porous area of skull, where it then synapses with the olfactory bulb. The olfactory bulb has several cell types, and only one of these, inhibitory granule cells, is continually regenerated via neuroblasts migrating along the rostral migratory stream from the sides of the lateral ventricles. These cells are thought to play a role in associative learning and coding of new olfactory cues. The olfactory nerve does not have a capacity for self-renewal, nor do any of the olfactory receptor cells.

Furthermore, there is more than one area where neurons undergo continual self-renewal. The dentate gyrus of the hippocampus also fosters a neurogenic niche, and these new cells have important implications for learning, memory, stress, and emotion that we are just beginning to understand.

Thirdly, we don't really know if neurogenesis in the olfactory bulb has anything at all to do with the observed results because this was not measured in the study, but it is a plausible hypothesis for future study.

As a side note, one of the very intriguing aspects of neurogenesis is that after cortical injuries such as trauma or stroke, neuroblasts from the ventricles migrate toward the lesion, rather than toward the olfactory bulb. These cells are capable of forming electrochemically active synapses at the lesion site and appear to aid in recovery. Unfortunately, astrocytic scarring and inflammation limit the regenerative capacity of these cells - but this is an area of intense research in the field of neurotrauma. My current (undergraduate) research is focused on analyzing the effects of post-injury recovery environment (for rats) on subventricular and hippocampal neurogenesis.

For a good summary on neurogenesis:

Comment Re:It is a farce. (Score 1) 626

"It's a distribution problem", which is to say "It's a capitalism problem".

This is exactly right. World hunger today is an emergent consequence of the global capitalist economy. People who were once able to grow crops to feed their families now have their land aggressively taken over by corporations (often with threats of violence). They then have no choice but to work growing whatever luxury crops the corporation dictates, such as hot peppers or coffee - crops that are rarely capable of sustaining a community. Then, whenever the value of that crop plummets or there is a drought, these communities are left without money to buy food.

Even during the worst famines, marketplaces can be seen selling an abundance of food. Those that die of hunger die not because there isn't food available. They die because they cannot afford it.

Comment Re:There is more to it. Or actually, less. (Score 2) 203

The fact that their results were insignificant means something different in statistics than it does in everyday speech. What it means is they are less than 95% certain their results were due to changes in the independent variable (Megaupload being shutdown or not) rather than chance.

Typically this means you can't make any conclusion about the strength or direction of the correlation.

Comment In favor of algorithms (Score 2, Informative) 245

I know there is a general backlash to the increasing use of algorithms in determining major decisions such as hiring. However, from a quantitative standpoint interviews have been shown to be extremely inaccurate as a judge of future job performance. There are simply far too many opportunities for bias on the interviewers part and so they tend to be neither reliable nor valid. Irrelevant characteristics such as appearance end up having far too much weight due to the halo effect. If you want the best result, depending on faulty human judgement is often the wrong choice.

For example, the Apgar score for judging the stability of newborn babies was designed to combat biases on the part of delivery room doctors. Prior to the use of this score, doctors rated how healthy newborns were based on a wide-range of criteria, and each doctor did it differently. When the Apgar score was introduced, it standardized the process by rating newborns on five categories: skin complexion, pulse rate, reflexes, muscle tone, and breathing. The result was that the error introduced by human bias was reduced and countless babies have been saved by quick intervention.

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