Medescape

Skepticism, Medicine and Science News

Fast Food Advertising

A new study finds that banning fast food advertising during children’s TV-shows could reduce obesity in children ages 3-11 by 18%. In children ages 12-18 the effect would be less, about 14% according to the study. 

The study was published in the Journal of Law and Economics, and conducted by researchers from the National Bureau of Economic Research (NBER) with funding from the National Institutes of Health. The researchers used data from the 1979 Child-Young Adult National Longitudinal Survey of Youth and the 1997 National Longitudinal Survey of Youth, enabling them to assess the viewing habits of over 13,000 children.

The researchers pointed out that implementing a ban on advertising might not be the most practical thing to do. The only countries having this kind of ban against commercial sponsorship of children’s TV-shows are currently Norway, Sweden and Finland, and these countries have a much more of a tradition for government involvement in these kinds of matters than the US. Another solution might be to eliminate the tax deductibility that comes with advertising. Since advertising is considered an expense it reduces the company’s income and thus the amount of tax. Eliminating the deductibility would in effect mean that advertising would become about 54% more expensive, and even though it would be less effective than an advertising ban, it would still reduce by about 5-7%.

November 30, 2008 Posted by | Economics, Medicine | , , , , , , , , , , , , , , , , , | Leave a comment

Photons to Power Nanomachines

Photons are elementary particles and the basic units of light, and they are capable of exerting forces. Recently, this force was shown to be strong enough to power a small, mechanical resonator, in other words a proof of concept that may lead to a new way of powering nanoscale machines. The research was done by Hong Tang et al at Yale University. They designed and tested a device that was able to take advantage of the optical gradient force to create vibrations. The device channelled incoming light through an extremely thin passage, only about 110 nanometres wide, in a photonic circuit. This caused the material to resonate at right angles to the beam. Even though the force generated is extremely small, the researchers claim it is strong enough to power small-scale devices, and since light can easily be beamed at large areas at a time, several devices could be powered with little effort. 

A picture of the photonic circuit with one of the resonators highlighted. 

The full article can be found here.

November 29, 2008 Posted by | General Science, Physics | Leave a comment

Science Quickies 3

A new study in mice shows that increased calcium sensitivity in the heart can lead to an irregular heartbeat. 

Scientists have identified 13 new tumor-suppressing genes in liver cancer. 

Scientists have calculated what they believe is the fastest 100-meter sprint time humanly possible. This was done using a mathematical model, and the time was found to be 9.48 seconds. 

A meteor streaking across parts of Canada last week was caught on video:

November 28, 2008 Posted by | General Science | , , , , , , , , , , , , , , , , | Leave a comment

Hubble Captures Two Ginormous Stars

A new picture from the Hubble Space Telescope shows two massive stars, WR 25 and Tr16-244, located in the open cluster Trumpler 16. This cluster lies within the Carina Nebula, approximately 7500 light years from earth. The nebula is home to many massive stars, including Eta Carinae, a supermassive luminous blue variable star with a luminosity four million times that of our sun, and a mass of 100-150 solar masses. WR 25 and Tr16-244 are not as big as Eta Carinae, but they are still pretty massive. 

WR 25 is located near the centre of the picture (the most blue of the big stars). It is binary star, and the largest of the two stars is a Wolf-Rayet star with a mass of about 50 solar masses. Wolf-Rayet stars are stars with a mass of >20 solar masses, and they loose their mass extremely rapidly due to a strong solar wind, typically about nine orders of magnitude more rapidly than our sun. The smaller star in the binary system is thought to have a mass of about half that of the other. 

Tr16-244 is located just to the left and up from WR 25, and is the third brightest star in the picture. The second brightest is a low-mass star much closer to earth (and thus it appears more luminous). This is a triple star, two of which are so close to each other that it took a while to determine they were in fact two separate stars. The third uses hundreds of thousands of years to orbit the first two. 

These new observations were made as part of a project led by Jesús Maíz Apellániz from the Instituto de Astrofísica de Andalucía in Spain, and consist of astronomers from the US, Argentina, Spain and Chile.

November 27, 2008 Posted by | Astronomy | , , , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

New Insight Into Familial Early-Onset Parkinson

A new study that will appear in the December 1, 2008 print issue of the Journal of Cell Biology provides new insight into the mechanisms of how mutations in the Parkin gene (PARK2) are linked to Parkinson’s Disease (PD). Specific genetic mutations have been known to correlate with early-onset PD, with Parkin, LRRK2 and PINK1 being the most studied. PINK1 have even been found to cause a type of PD indistinguishable from late onset idiopathic PD, and this suggest that genetic mutations may play a role in sporadic PD. 

The study, by Narendra et al., explains that E3 ubiquitin ligase (Parkin) is linked to mitochondrial damage in that the protein may help trigger the removal of damaged mitochondria. Mitochondrial damage have been investigated as a possible candidate for the pathological process of PD through mitochondria-induced apoptosis (although other theories currently have more general support for the cause of iPD, such as proteolytic stress, inflammation and oxidative stress), and the researchers found that in cells that had mitochondrial damage, Parkin had translocated from the cytoplasma to the mitochondria. This translocation was shown to trigger phagosomes to degrade the mitochondria, and thus prevent a possible mitochondria-induced apoptosis.

November 26, 2008 Posted by | Medicine | , , , , , , , , , , , , , , , , , , , , | Leave a comment

Binary Star Explosion

For the first time in over 100 years, scientist have witnessed the explosion of a binary star inside a planetary nebula. Astronomers at University College London predict that the two stars eventually may spiral into each other and trigger a much larger supernova explosion. 

A planetary nebula is a glowing shell of gas and plasma formed by certain types of stars when they reach the red giant phase of their lives. During this phase, the outer layers of the star are expelled by strong pulsations and solar winds. The core of the star then emits ultraviolet radiation that ionises these ejected layers, and they radiate out as a planetary nebula. 

A nova, on the other hand, is nuclear explosion caused by accretion of hydrogen onto the surface of a nearly-dead white dwarf star.  In a closed binary system, the nova occurs as matter is transferred from one star to the other, which eventually causes a cataclysmic thermonuclear explosion. Novas are in themselves not uncommonly observed, but a nova inside a planetary nebula is rarely seen. The nova illuminates the surrounding gases and plasma as the light passes through it, and the UCL scientist say this could help us understand more about the life cycle of stars. 

The has been given the name V458 Vulpeculae, and it could turn out to provide researchers with an opportunity of observing how a nova might evolve into a supernova. 

The top image was taken in May 2008, and the bottom in September 2008. The changes that occur due to the ongoing nova are clearly visible. From University College London

November 25, 2008 Posted by | Astronomy | , , , , , , , , , , , , , , , , , , , , | Leave a comment

Completely Random

Randomness is a tricky thing. It is easily found in the world around us, but if you want to actively generate, say, a random sequence of numbers, it suddenly becomes quite elusive. The more advanced hand-held calculators have a program that generates, seemingly, random numbers by using specific algorithms, but the fact is that this is not true randomness, but rather pseudorandomness. This means that although the number sequence generated may seem random to a person, a statistical analysis may reveal subtle patterns and skews in the data. For the applications of a pocket calculator, this is probably not a big deal. However, random numbers are a big part of modern cryptography, and are used in, for example, Internet banking. It would be inherently bad if your personal bank ID could be easily predicted by a large statistical analysis of ID-data, so true randomness would be an advantage for these applications.

One common pseudorandom number generator is the linear congruential generator (LCG). It uses the following algorithm to generate seemingly random numbers (click the link for a proper explanation of the equation): 

This is one of the oldest methods for generating random numbers, but it has several problems, and is subsequently not recommended when high-quality randomness is needed.  

A more recent algorithm is the Mersenne twister developed in 1997. It is by far more complicated than the LCG, but also produces a better result. It passes a lot of different tests for true randomness, including the Diehard tests and even some of the more rigorous TestU01 Crush randomness tests (go here for a brief description of these tests, and for the really daring, go here for a more….detailed document). 

To generate a truly random sequence of numbers, a hardware random number generator is required. These devices uses random processes in nature to generate randomness. These processes can range from radioactive decay, thermal noise, avalanche noise and atmospheric noise. These devices have been known to silently break over time though, and the true randomness of the numbers generated should therefore be tested from time to time. 

Another problem with these devices have been that they do not generate random numbers very fast. Typical existing devices only generate a random string of numbers with a speed of 10s-100s megabits per second. To deal with this problem, a new method for generating random numbers have recently been developed. According to the researchers, the method is capable of generating random numbers with a speed of up to 1.7 gigabits, which is 10 times faster than previous devices. The method was developed by researchers at Saitama University in Japan, and uses semiconductor lasers. The process itself is really quite simple, and consist of an external mirror that reflect some of the light back inside the laser. This feedback causes the light to oscillate randomly, and this is then converted into an AC current and further to a binary signal. In total, the process uses two of these lasers to produce a single, random number sequence. According to the researchers, Atsushi Uchida and Peter Davis, the system can be built into cryptographic systems for secure network links with very little extra cost.

November 24, 2008 Posted by | General Science, Math, Physics | , , , , , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

New Method for Detecting Colon Cancer

The standard method for detecting colon cancer is a colonoscopy, but this is often painful, and a lot of patients choose not to undergo the procedure. Therefore, a new method of detecting colon polyps, precursors to colon cancer, have been developed. The test consist of a simple blood test that looks for distinct biomarkers that are typical for polyps. If a patients is found to be at risk, they would be more likely to agree to a colonoscopy to see if the polyps have advanced to form cancerous adenomas. The researchers say that the test can identify polyps correctly about 80% of the time. 

A colon polyp

November 23, 2008 Posted by | Medicine | , , , , , , , , , , , , , | Leave a comment

CAM in Med Schools

A recent survey showed that non-white medical students are more likely than white to reject CAM, or complementary and alternative medicine. The study consisted of two sets of questionnaires, one which the students answered in their first year of medical school, and another in their fourth year. The survey also showed that students opinions tended to solidify over time, meaning that if you began with a somewhat positive attitude towards CAM, you would most likely become more positive over time, and vice versa. Also, the researchers reported that the overall attitude towards CAM did not change significantly between the two surveys. The study was conducted by researchers at four medical schools, Peninsula (UK), Birmingham (UK) Georgetown (USA) and Auckland (New Zealand). 

I have no problem with these kinds of studies being conducted, but I do have some issues with some of the things Hakima Amri, the main author, says. One quote from her is (talking about why the students who became more negative towards CAM did so): 

One explanation for the decrease in positive attitude about CAM may result from the students’ increased medical knowledge and contact with skeptical clinicians, which are not counter-balanced by CAM teaching.

It almost sounds as if she thinks that is a bad thing. And the sentence doesn’t even make sense to me. According to her, as students learn more and knows more about medicine, they become more negative towards CAM when this is not counter-balanced by CAM teaching. So, the bottom line is that the science-based teachings of medicine are not balanced with non-science-based teachings of CAM. When I go to a doctor I would like him to have an education based on science, wouldn’t you? I am not completely sure what Hakima Amri’s angle on CAM is, but she has done an awful lot of studies looking into medical students attitudes towards CAM. In a study in which she was one of the co-authors, she reported that over 10% of first/second year medical students wanted to be taught healing touch so they could provide it themselves to patients. 10%! Healing touch! It just boggles the mind, at least my mind. 

I have one problem with the methods used in the study. Not all of the students who took part in the original survey took part in the second. Only students who “indicated willingness to complete the second questionnaire” were invited to do so. This could cause a bias in the data, as I believe many students who originally did not really care much for CAM wouldn’t be bothered to take the second survey. Students who on the other hand wanted CAM in ther curriculum would in my opinion be much more likely to also take the second survey. Thus, the overall attitude of CAM could very well have become more negative over time, and not be as stable as the study reports. 

Personally I don’t really understand all the fuss about CAM. What’s wrong with trusting science? Why not stick to drugs and treatments that have been thoroughly tested for safety and efficacy? The difference between a drug bought at the pharmacy and a herbal pill is that the latter contains a varying amount of active ingredient, and the effects and side effects have not been scientifically tested. But they are both still drugs. Would you take a drug developed by a drug company if they told you they had not tested it for…well…anything? Herbal remedies are basically that; untested and sometimes unsafe (more often than you would think also).

November 22, 2008 Posted by | General Skepticism, Medicine | , , , , , , , , , , , , , , , , , , , | Leave a comment

New Dolphin Species

Due to unforeseen, unwanted and, I presume, unintended events, the network at my flat died over night. This post will therefore be quite short, since I’m doing it from a public computer.

I’ll just inform everybody that a new species of dolphin have been discovered near southern Australia. It was discovered using DNA analysis, and has been given the name Southern Australian bottlenose.

The Southern Australian bottlenose dolphin. Credit: Macquarie University

November 21, 2008 Posted by | Biology, General Science | , , , , , , , , , | Leave a comment