When a human egg is ready to be fertilised, it releases a chemical that signals “come hither” to nearby sperm. Now we know how this signal whips sperm into shape, which might make it possible to develop non-hormonal contraceptives that turn the signal off.
Although biologists have known for decades that egg cells provide sperm with a little chemical encouragement to reel them in, the molecular nature of this interaction has remained elusive.
‘If you think you understand it, you don’t know nearly enough about it.’
It will soon be 200 years since the birth of Charles Darwin and 150 years since the publication of On the Origin of Species, arguably the most important book ever written. In it, Darwin outlined an idea that many still find shocking - that all life on Earth, including human life, evolved through natural selection.
Most of us are happy to admit that we do not understand, say, string theory in physics, yet we are all convinced we understand evolution. In fact, as biologists are discovering, its consequences can be stranger than we ever imagined. Evolution must be the best-known yet worst-understood of all scientific theories.
So here is New Scientist’s guide to some of the most common myths and misconceptions about evolution.
Stem cells derived from human menstrual blood have, in mice, prevented limbs with restricted blood flow from withering. Trials in humans facing amputations are expected to start next year.
Now Thomas Ichim, of MediStem, and his team have published a proof-of-principle study in mice, showing that the endometrial stem cells revitalise damaged limbs in much the same way that bone-marrow-derived stem cells do.
“The following is an actual question given on a University of Washington chemistry mid term. The answer by one student was so profound that the professor shared it with colleagues, via the Internet, which is, of course, why we now have the pleasure of enjoying it as well:
“Bonus Question: Is Hell exothermic (gives off heat) or endothermic (absorbs heat)?”
Most of the students wrote proofs of their beliefs using Boyle’s Law (gas cools when it expands and heats when it is compressed) or some variant.
One student however, wrote the following…
First, we need to know how the mass of Hell is changing in time. So we need to know the rate at which souls are moving into Hell and the rate at which they are leaving. I think that we can safely assume that once a soul gets to Hell, it will not leave. Therefore, no souls are leaving. As for how many souls are entering Hell, let’s look at the different religions that exist in the world today.
Most of these religions state that if you are not a member of their religion, you will go to Hell. Since there is more than one of these religions and since people do not belong to more than one religion, we can project that all souls go to Hell. With birth and death rates as they are, we can expect the number of souls in Hell to increase exponentially. Now, we look at the rate of change of the volume in Hell because Boyle’s Law states that in order for the temperature and pressure in Hell to stay the same, the volume of Hell has to expand proportionately as souls are added.
This gives two possibilities:
1. If Hell is expanding at a slower rate than the rate at which souls enter Hell, then the temperature and pressure in Hell will increase until all Hell breaks loose.
2. If Hell is expanding at a rate faster than the increase of souls in Hell, then the temperature and pressure will drop until Hell freezes over.
So, which is it???
If we accept the postulate given to me by Teresa during my Freshman year that, ‘It will be a cold day in Hell before I sleep with you,’ and take into account the fact that I slept with her last night, then number two must be true, and thus I am sure that Hell is exothermic and has already frozen over. The corollary of this theory is that since Hell has frozen over, it follows that it is not accepting any more souls and is therefore, extinct……leaving only Heaven, thereby proving the existence of a divine being which explains why, last night, Teresa kept shouting ‘Oh my God.’
1. THE CALM Not a single visual of chest-beating or wild grief. Sorrow itself has been elevated. 2. THE DIGNITY Disciplined queues for water and groceries. Not a rough word or a crude gesture. 3. THE ABILITY The incredible architects, for instance. Buildings swayed but didn’t fall. 4. THE…