1

Cells, Microbes & Viruses / Re: Are bacteria intelligent?

« on: 18/11/2013 01:55:33 »

Communities of bacteria also employ decision-making processes involving quorum sensing, where each bacterium produces and emits signaling molecules, and in turn, senses those signaling molecules from other bacteria and modifies its gene expression and/or behavior based on the levels that it senses. In this way, bacteria can behave as one organism based on the size of their community.

For example, a few bacteria inside a human body would not be effectively virulent and would be defeated if they attacked the body. However, if they waited for sufficient numbers, then they could produce a sufficient virulence to overwhelm the body's defenses and complete their objective.

I crudely described it here, so perhaps someone else could give a better or more specific example.

2

Physiology & Medicine / Re: Why don't maternal IgGs attack foetal tissues?

« on: 17/11/2013 22:00:04 »

Regarding the mother's immune system contact with non-mother cells, what about it attacking the placenta itself? Certainly it comes into contact with the placenta, right?

The placenta is a very invasive organ, and in an extreme placentation called placenta percreta, it can grow through the uterine wall and into the rectum or bladder, which is obviously life-threatening, and yet the mother's immune system apparently allows it. 

3

Marine Science / Re: Why is ocean marine life more colorful than in lakes?

« on: 17/11/2013 21:19:40 »

So, what is it in lakes that discourages the same coral growth that one finds in the sea?  Perhaps not high enough levels of free calcium in the water.

Does calcium readily leach out of soil? Yes, it would, wouldn't it, because it's an alkaline ion. So it accumulates in the oceans where it's readily used to make coral.

4

Physiology & Medicine / Re: Tip of the tongue experiences

« on: 08/11/2013 20:20:45 »

I experienced this working on crossword puzzles. The best way for me to describe it is like crawling along tree branches looking for fruit. I see a fruit (that is, line of sight, or shortcut method) that seems to be on a particular branch (a methodical method), and I crawl towards it, but I can't get it because I'm on the wrong branch. So I must *go back* and select another branch.

It's the *going back* and selecting another branch that people have a problem with. Similarly, let's say you have a simple, spiral maze. If you put a chicken in the middle and a cat on the outside, it will easily spiral in towards the chicken and get it because it's always getting closer to it. BUT, if you put the chicken on the outside and the cat in the middle, it can't figure out how to get the chicken because its problem-solving powers cannot accept going farther away from it in order to get it.

5

Physiology & Medicine / Re: What causes generalized numbness and poor balance?

« on: 06/11/2013 09:30:26 »

Has a neurovascular specialist reviewed the images for stenosis of the vertebrobasilar distribution system?

6

Plant Sciences, Zoology & Evolution / Re: Animals get smaller in response to global warming

« on: 05/11/2013 05:37:56 »

Two terrestrial ecogeographical rules may come into play.

According to Bergmann's Rule on body size first proposed in 1847, within the same species of warm-blooded animals, individuals from populations living in warmer environments tend to have less body mass than do those from populations in colder areas because of the selective advantage that less body mass provides. A smaller body produces less internal heat and radiates relatively more of it into the environment because the skin’s surface area is relatively larger.

According to Allen's Rule on appendage size first proposed in the 1870s, within the same species of warm-blooded animals, individuals from populations living in warmer environments tend to have longer/larger appendages (limbs, ears, tail, etc)  than do those from populations in colder areas because of the selective advantage longer/larger appendages provide. Longer or larger appendages provide greater surface area and can radiate more heat into the environment because the skin’s surface area of the appendages is greater.

Similarly, the fennec fox, the smallest species of canid in the world, lives in the desert and has large ears.

7

Question of the Week / Re: QotW - 13.07.11 - Power from Poo?

« on: 23/10/2013 09:11:07 »

Rural people in developing countries have used sewage biogas generators for decades.

Do-It-Yourself Methane Generator

8

Cells, Microbes & Viruses / Re: Why is the mould on this apple arranged in stripes?

« on: 07/10/2013 22:07:05 »

Curious: Has the mold formed several rings (plural) or one continuous spiral (singular)?

9

Technology / Re: How could we best advertise our presence to aliens?

« on: 28/09/2013 05:32:22 »

Methane, plenty of methane. Baked beans and sauerkraut, anyone?

10

Technology / Re: Concave glass-clad skyscraper (doh!)

« on: 12/09/2013 16:33:27 »

Coat the windows with a material that would disperse the reflected sunlight.

11

Physiology & Medicine / Re: Wny "under the tongue"?

« on: 12/09/2013 16:26:38 »

With nitroglycerine, it's a matter of quick absorption to relieve an ongoing heart attack as soon as possible and to bypass the digestive system, which would take too much time and would destroy it, which would make it useless. 

The digestive system would digest nitroglycerine. Enduring the rigors of digestion is also why some protein-based medicines (such as insulin) are injected, otherwise they would be digested (ie, reduced to its parts) and, thus, rendered useless.

The "A" in the term "ADME" stands for Absorption.

12

Technology / Re: Concave glass-clad skyscraper (doh!)

« on: 10/09/2013 18:49:56 »

a curved building with solar reflection problems


Hmm.....

Eliminate the curves — too difficult

Eliminate the building — far too difficult

Eliminate the Sun — infinitely too difficult

Eliminate the reflectivity — sounds reasonable *

* "How often have I said to you that when you have eliminated the impossible more difficult solution, whatever remains, however improbable undesirable, must be the truth reasonable solution?" — Sherlock Holmes

13

General Science / Re: Forensic experts 'biased towards side which pays them'

« on: 07/09/2013 01:57:27 »

The OP's study involved testimony/opinions from "experts" in the "soft sciences" of psychology and psychiatry.

I remember the day-care child-abuse hysteria that swept the US. Some experts were hired in multiple cases, and the children's testimony in those cases described the same abuse — clowns, "secret" rooms, morbid rituals, baby sacrifices, etc — allegations that may have only existed in the minds of the "experts" who apparently implanted false memories into the minds of little children.

However, we are now coming to realize that, in some ways, experts in physical evidence also can be far from impartial.

The case against chemist Annie Dookan alleges that she habitually ignored good science in order to find defendants more guilty than they actually were.

People are now beginning to question the reliability of the methodology of some kinds of forensic analysis, and they're finding that other physical "analysis" isn't so scientific. For example, the forensic disciplines of  hair-match analysis and bite mark analysis has come under serious scrutiny.

Analyses that result in opinions (versus analysis by instruments) are apparently more susceptible to being more subjective than objective.

14

New Theories / Re: thrust does not work in space

« on: 05/09/2013 17:18:40 »

In space, objects have no weight but still have the same mass.

...and so they develop equipment and methods to measure mass, such as people's masses as part of monitoring their health. Quite the high-tech "bathroom scale". What you don't notice is that, according to Newton's Third Law of Motion, as the person moves "up" and "down", the ISS is moving (ever so slightly) "down" and "up".

15

Physiology & Medicine / Re: Discuss: Tickling your brain: why do we laugh?

« on: 01/09/2013 01:40:34 »

Bob Mankoff on the anatomy of a New Yorker cartoon

16

Plant Sciences, Zoology & Evolution / Hummingbirds: Nutritional intake → Nectar: Ideal food?

« on: 28/08/2013 00:45:24 »

The recent thread on the hummingbird-like insect, the hummingbird hawkmoth, prompted me to search YouTube, where I found Rescued Baby Hummingbird.

The video showed the hummingbird drinking what was probably sugar water, which caused me to wonder. Sugar is a carbohydrate, containing only carbon, hydrogen and oxygen. But a hummingbird needs all sorts of chemicals. So, a hummingbird could not subsist only on sugar water because it would suffer malnutrition and die.

A hummingbird's (or hummingbird hawkmoth's) food in nature is nectar, which, if it's the bird's only food source, must contain all sorts of chemicals needed for survival, growth, etc. Wikipedia says that nectars contain all sorts of chemicals, so nectar is the ideal food — for hummingbirds, at least.

So, I'm wondering if nectar is the ideal food for all species (including humans), or just the animals that naturally feed on it? Nectar seems to have a high sugar content to restore the energy required to collect it. Do nectar-feeding animals depend on nectar from particular plants, or will any plant do? What if these animals are restricted to one species of plant; will the animal survive?

It seems that the animals and their nectars co-evolved. Has anyone read/studied anything about this?

Thanks.

17

Technology / Re: How does one modify a 4-stroke engine to run on compressed air?

« on: 04/08/2013 02:58:59 »

Okay, so how would the engine or vehicle operator control the power being produced? We wouldn't want to drive around with maximum power all the time. The carburetor wouldn't be necessary because there's no need to regulate the fuel/air mixture, right?

18

Technology / Re: What does work to rule mean for air-traffic control?

« on: 02/08/2013 15:32:45 »

ATCs are unionized, so they have contracts with their employers. More money may not always be the objective of work-to-rule campaigns.

If you think of ATCs as high-tech traffic police, they provide a service to the public, so they feel an obligation to ensure the public receives sufficient coverage. Air travel is also a monopoly in that there are no other realistic alternatives that the public can seek. Traveling by car, rail or ship takes much longer, and most people have become accustomed to the convenience of flying.

But air traffic control is a hectic job, so time off for ATCs is considered precious, and the extra money for working voluntary overtime (even though paid at a higher pay rate) may not be worth the bother. So these campaigns might be to coerce their employers to hire more ATCs, instead of asking the current ATCs to do their employers a favor in working overtime.

19

Physiology & Medicine / Re: Discuss: Tickling your brain: why do we laugh?

« on: 31/07/2013 14:30:12 »

Why do we laugh? 

Perhaps to express (or to "release" or "disarm") cognitive dissonance. People mostly laugh at "funny" situations or at jokes, and there's almost always some cognitive dissonance in a funny situation). However, laughing is also a known response to nervousness, stressful situations, even extremely stressful situations, although such "laughs" might only be a chuckle or two or just holding the "face" of a laugh (as when stumped or puzzled), but it may also be quite extensive, as in hysterics.

Any pleasure/bonding derived from laughing in groups might come from the realization that everyone in the group suffers the same cognitive dissonance from the same situation and that they trivialize that dissonance. Notice how people tend to question someone about why they didn't laugh when everyone else thought it was "funny".

Also consider the other definition for "joke" — something not to be taken seriously. So, in this way, we mean ... yes, it doesn't make sense (ie, some cognitive dissonance exists), but don't take it seriously. We "laugh" things off.

20

Cells, Microbes & Viruses / Re: How do cells migrate in a developing embryo?

« on: 30/07/2013 17:40:40 »

1. It's a specific type of chemical gradient for each migration group, at least concerning the development of the cerebral cortex. The migrating cells aren't in their ultimate stage, because of the amoeboid movement they require and because their ultimate stage forms connections with approximately 50,000 other neurons, and the two don't seem compatible (at least to me).

2. It's more like the scaffolding they must climb through, like a kid climbing out of a jungle gym. The scaffolding is the existing neurons in the cerebrum (I would say mostly white cells), and purely structural cells. such as glia cells, and when the migrating neurons reach the cortical regions, they climb through any previous layers of cortical cells that have gone before and installed themselves at the surface. I'm not familiar with the entire scaffolding structure of the brain, but I do know of the glia cells, and there may be other components, including those that are not cells.

On the origin of the scaffolding, there's at least the white brain cells and glia cells, where the glia cells are purely structural. What I remember of the white cells, they seem mostly to be interconnections of regions within the cerebrum (such as, between the various areas of the visual system), and with the rest of the body (such as the muscles and the senses). I'm not remembering much about the scaffolding, and I don't remember about its development.