Older men like me are routinely given a PSA test for prostate cancer as part of our check-ups. My numbers fluctuated from year to year. Some years my number would rise slightly and my physician would alert me to it, but the next year it would drop. I never did anything about it since I was not convinced that the tests were conclusive enough. Now a new study seems to indicate that my skepticism was justified, since the PSA seems to have high levels of false negatives and even higher levels of false positives.

This latest study was carried out in Norrkoping in Sweden. It followed 9,026 men who were in their 50s or 60s in 1987.

Nearly 1,500 men were randomly chosen to be screened every three years between 1987 and 1996. The first two tests were performed by digital rectal examination and then by prostate specific antigen testing.

The report concludes: “After 20 years of follow-up, the rate of death from prostate cancer did not differ significantly between men in the screening group and those in the control group.”

The favoured method of screening is the prostate specific antigen (PSA) test.

However, around 15% of men with normal PSA levels will have prostate cancer and two-thirds of men with high levels of PSA do not in fact have prostate cancer.

One study has suggested that to prevent one death from prostate cancer you would have to screen 1,410 men and treat 48 of them. (My italics)

Five years after the Dover trial, Scientific American looks at the state of teaching evolution.

(via Machines Like Us.)

I was stunned recently by this report that there may be a massive new planet that we did not know about in our very own Solar system. I thought this must be a hoax report but apparently it is being considered as a serious possibility.

The hunt is on for a gas giant up to four times the mass of Jupiter thought to be lurking in the outer Oort Cloud, the most remote region of the solar system. The orbit of Tyche (pronounced ty-kee), would be 15,000 times farther from the Sun than the Earth’s, and 375 times farther than Pluto’s, which is why it hasn’t been seen so far.

But scientists now believe the proof of its existence has already been gathered by a Nasa space telescope, Wise, and is just waiting to be analysed.

You would have thought that our knowledge of our own stellar neighborhood was complete but apparently not. The suggestion that Tyche existed was first made as far back as 1999 but not everyone is persuaded that it exists.

We should know with greater certainty either way by 2012. This is what makes science so much fun. There are always new discoveries to look forward to.

The idea that the electromagnetic radiation can exert pressure is an interesting idea that I taught in my physics courses. As an example, the idea of using the pressure from solar radiation to power a spacecraft has been around for a long time, and I used to give this as a homework problem.

It looks like it has finally come to fruition. Japan used one to fly by Venus in 2010 and now NASA has deployed one to orbit the Earth. Plans are underway to use one to fly to Jupiter later in the decade.

(via Machines Like Us.)

Some of you may be aware that many parents are not giving their children the MMR (measles, mumps, rubella) vaccine out of fears that it may cause autism. These fears were generated by a paper published in 1998 by the British medical journal Lancet by Andrew Wakefield and others suggesting such a link. The findings were challenged but the journal only withdrew the paper in 2010.

The British Medical Journal has now published a detailed investigation and concludes that all of the twelve original cases reported had had their data misreported or altered in order to make the link.
[Read more…]

Of all the arguments that are used by religious people against evolution, the most fraudulent is that there are no transitional forms between species. People who say this either willfully ignore the evidence that does exist or think that a transitional form must be a hybrid between two currently existing species.

Do you think that no one could be that stupid? Behold the infamous crocoduck argument.

[Read more…]

Critics of evolution sometimes try to argue that the mechanism of natural selection works too slowly to produce the world we now have in the time that was available. P. Z. Myers shows why that argument is wrong.

… and can thus work together for good or bad. Fascinating.