15 posts · 5,399 views
Science and reason is all about... science and reason. News and explanations of recent developments in the most intriguing branches of science. Philosophical and political issues of relevance are also discussed.
Charles Daney
15 posts
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- January 31, 2010
- 12:31 AM
- 42 views
Magnetic fields in gamma-ray burst jets
by Charles Daney in Science and Reason
Gamma-ray bursts (GRBs) are the most dramatic short-lived violent events observed in the universe. They are often described as releasing a quantity of energy, in less than a minute, that is at least as much as a star like the Sun releases in its entire 10 billion year lifetime. Since the first detection of a gamma-ray burst in 1967, the central question has been to determine the nature of the process or processes that can release so much energy so quickly.We've discussed gamma-ray burst several ........ Read more »
Steele, I., Mundell, C., Smith, R., Kobayashi, S., & Guidorzi, C. (2009) Ten per cent polarized optical emission from GRB 090102. Nature, 462(7274), 767-769. DOI: 10.1038/nature08590
- January 4, 2010
- 03:07 AM
- 113 views
Space is very fine-grained
by Charles Daney in Science and Reason
It would take you a lot longer to hike a significant distance over very hilly terrain than it would over a completely flat plain. For much the same reason, it would take light longer to cover the same distance depending whether the space through which it moves does or doesn't have large "hills".But what does it mean for space to contain "hills"? And how large do "hills" need to be to make a difference?Consider the second question first. There's no natural place on Earth that is perfectly flat, o........ Read more »
Abdo, A., Ackermann, M., Ajello, M., Asano, K., Atwood, W., Axelsson, M., Baldini, L., Ballet, J., Barbiellini, G., Baring, M.... (2009) A limit on the variation of the speed of light arising from quantum gravity effects. Nature, 462(7271), 331-334. DOI: 10.1038/nature08574
- November 2, 2009
- 01:26 AM
- 164 views
Most Distant Known Object In The Universe
by Charles Daney in Science and Reason
On April 23 of this year the Swift Gamma-Ray Burst Telescope detected, just as it was designed to do, a gamma-ray burst (GRB). Within less than a day two of the most powerful Earth-based telescopes had begun studying the quickly fading light of the object, known as GRB 090423. (There were other observatories investigating it as well.)Because the light from GRBs fades so rapidly, most such objects are detected from space-based instruments that are especially designed for the purpose, like Swift. ........ Read more »
Tanvir, N., Fox, D., Levan, A., Berger, E., Wiersema, K., Fynbo, J., Cucchiara, A., Krühler, T., Gehrels, N., Bloom, J.... (2009) A γ-ray burst at a redshift of z ≈ 8.2. Nature, 461(7268), 1254-1257. DOI: 10.1038/nature08459
Salvaterra, R., Valle, M., Campana, S., Chincarini, G., Covino, S., D’Avanzo, P., Fernández-Soto, A., Guidorzi, C., Mannucci, F., Margutti, R.... (2009) GRB 090423 at a redshift of z ≈ 8.1. Nature, 461(7268), 1258-1260. DOI: 10.1038/nature08445
- October 26, 2009
- 02:22 AM
- 152 views
A surprisingly compact early galaxy
by Charles Daney in Science and Reason
Astronomers are beginning to learn significant details of the structure of galaxies in the early universe. And what they're learning is rather surprising: at least some early galaxies are almost as massive as otherwise similar galaxies in the present universe, yet they are much smaller in linear size, by a factor of five, thus much more compact.What time period are we talking about here? It's not actually the time that the earliest galaxies formed, which was less than a billion years after the b........ Read more »
van Dokkum, P., Kriek, M., & Franx, M. (2009) A high stellar velocity dispersion for a compact massive galaxy at redshift z . Nature, 460(7256), 717-719. DOI: 10.1038/nature08220
- October 10, 2009
- 05:15 AM
- 211 views
Telomerase and Wnt signaling
by Charles Daney in Science and Reason
Now that research into telomeres and telomerase has (finally) garnered a Nobel Prize, it's a good time to write about recent research on the subject.Seminal work on telomeres by Elizabeth Blackburn, one of the Nobel winners, was published way back in 1978, and active studies have been going on ever since. So perhaps it's not surprising that the rate of new findings is not so rapid as occurs in newer areas – such as stem cells.But fascinating new results on telomeres and telomerase do still........ Read more »
Park, J., Venteicher, A., Hong, J., Choi, J., Jun, S., Shkreli, M., Chang, W., Meng, Z., Cheung, P., Ji, H.... (2009) Telomerase modulates Wnt signalling by association with target gene chromatin. Nature, 460(7251), 66-72. DOI: 10.1038/nature08137
- September 26, 2009
- 12:28 AM
- 238 views
Induced pluripotent stem cells with one transcription factor
by Charles Daney in Science and Reason
Just under three years ago, in October 2006, some important stem cell research was announced by a Japanese scientific team led by Shinya Yamanaka. The team showed how ordinary mouse skin cells could be transformed into cells that turned out to be pluripotent, just like embryonic stem cells (ESCs). The new cells were called induced pluripotent stem cells (iPSCs). Although "ground-breaking" is an over-used term, this research genuinely deserved the description.Aside from the fact that it could be ........ Read more »
Kim, J., Greber, B., Araúzo-Bravo, M., Meyer, J., Park, K., Zaehres, H., & Schöler, H. (2009) Direct reprogramming of human neural stem cells by OCT4. Nature. DOI: 10.1038/nature08436
- September 8, 2009
- 03:57 AM
- 236 views
New anti-cancer role for p53
by Charles Daney in Science and Reason
I suppose that just about everyone knows of the important role the p53 protein plays in protecting cells from becoming cancerous. The protein was identified 30 years ago and its gene (TP53) cloned soon thereafter. What's not so widely known is just how complex the operation of p53 in protecting against cancer really is. And very recent research shows the complexity is even more than previously thought. However, the complexity is to be expected, because evolution doesn't "design" cellular mechani........ Read more »
Suzuki, H., Yamagata, K., Sugimoto, K., Iwamoto, T., Kato, S., & Miyazono, K. (2009) Modulation of microRNA processing by p53. Nature, 460(7254), 529-533. DOI: 10.1038/nature08199
- August 17, 2009
- 02:14 AM
- 237 views
Inflammation, microRNA, and cancer
by Charles Daney in Science and Reason
If there's just one single point worth making about the biology of cancer, it would have to be "it's complicated".Cells in general, and animal cells in particular, are extremely intricate Rube-Goldberg-like mechanisms. Their correct functioning depends on the integrity of 20,000 or so genes (in the case of humans), and at least 5 times as many proteins whose form is specified by the genes. Damage to even one of a few thousand important genes can put a cell on the road to becoming cancerous. So t........ Read more »
Pedersen, I., Otero, D., Kao, E., Miletic, A., Hother, C., Ralfkiaer, E., Rickert, R., Gronbaek, K., & David, M. (2009) Onco-miR-155 targets SHIP1 to promote TNFα-dependent growth of B cell lymphomas. EMBO Molecular Medicine, 1(5), 288-295. DOI: 10.1002/emmm.200900028
- July 12, 2009
- 05:45 AM
- 373 views
Rapamycin and lifespan extension
by Charles Daney in Science and Reason
Will a pill containing the immunosuppressant drug rapamycin someday extend human lifespan a few years? In spite of the hopeful research announcements that appeared a few days ago, I wouldn't recommend getting one's hopes up just yet.This is a topic I've discussed before: Calorie restriction, TOR signaling, and aging. And for related stuff on mTOR: here.The executive summary is that inhibition of mTOR signaling has been shown to extend lifespan in yeast, roundworms, and fruit flies........ Read more »
Harrison, D., Strong, R., Sharp, Z., Nelson, J., Astle, C., Flurkey, K., Nadon, N., Wilkinson, J., Frenkel, K., Carter, C.... (2009) Rapamycin fed late in life extends lifespan in genetically heterogeneous mice. Nature. DOI: 10.1038/nature08221
- April 5, 2009
- 08:16 PM
- 463 views
Amino acid chirality
by Charles Daney in Science and Reason
We've discussed the mystery of amino acid chirality – the fact that all biological amino acids on Earth seem to be left-handed. Alternative chiral forms of molecules are called enantiomers. Previous discussion and background is here.In that earlier discussion we considered a hypothesis that was described last year. It is known that amino acids can be formed in interstellar space. The hypothesis suggests that the first amino acids on Earth were carried here by meteorites. Further, there was........ Read more »
Glavin, D., & Dworkin, J. (2009) Enrichment of the amino acid L-isovaline by aqueous alteration on CI and CM meteorite parent bodies. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.0811618106
- January 25, 2009
- 11:22 PM
- 585 views
DNA repair and cancer II
by Charles Daney in Science and Reason
I just wrote about this at some length, here.It's funny, sometimes, how there are a bunch of results released in a short time period on the same topic. Usually it's because there's a big meeting that covers the topic, or else the editor of some journal wants several papers on the topic.I've just come across three more papers on the topic and can't recall such a flurry of activity related to it. The papers were all published in different journals, and there doesn't appear to have just been a meet........ Read more »
T.-H. Kang, J. T. Reardon, M. Kemp, & A. Sancar. (2009) Circadian oscillation of nucleotide excision repair in mammalian brain. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.0812638106
- January 6, 2009
- 04:42 AM
- 644 views
Chinese food, umami, autism, schizophrenia, and cancer
by Charles Daney in Science and Reason
There's a fascinating interrelationship among the things mentioned in the title – and it takes us through equally fascinating topics in molecular cell biology and neurobiology.No, Chinese food has not been found to cause the listed maladies – although with the additives that the People's Republic of China seems to be allowing in many of its food products these days (e. g. melamine), who knows for sure?So what's the connection? Try monosodium glutamate (MSG). That, of course, is the s........ Read more »
Eric Howlett, Curtis Chun-Jen Lin, William Lavery, & Michael Stern. (2008) A PI3-Kinase–Mediated Negative Feedback Regulates Neuronal Excitability. PLoS Genetics, 4(11). DOI: 10.1371/journal.pgen.1000277
- December 22, 2008
- 04:17 AM
- 665 views
Zooming in on an early galaxy
by Charles Daney in Science and Reason
One of the key questions about galaxies concerns the process in which they form. Galaxies are made up of stars, but in general stars do not form in isolation – except for the very first stars in the universe, which we discussed here.More normally, stars form simultaneously in close proximity to each other as part of the larger process of galaxy formation. But galaxy formation can happen in one of at least two different ways. In the first case, the baryonic matter that will eventually form ........ Read more »
Daniel P. Stark, A. Mark Swinbank, Richard S. Ellis, Simon Dye, Ian R. Smail, & Johan Richard. (2008) The formation and assembly of a typical star-forming galaxy at redshift z ≈ 3. Nature, 455(7214), 775-777. DOI: 10.1038/nature07294
- November 24, 2008
- 05:59 PM
- 557 views
Politics as beauty contest
by Charles Daney in Science and Reason
Perhaps interest in politics has dropped off a lot now that the U. S. elections are over (for this year). But there's still some interesting political science that came up before the big event.Even though political scientists, year in and year out, are as busy publishing as any other kind, quite a number of research announcements were noted recently outside of traditional professional venues. That has tapered off now, but there were a number of items that seem to call for some comment here. So I........ Read more »
Joan Y. Chiao, Nicholas E. Bowman, & Harleen Gill. (2008) The Political Gender Gap: Gender Bias in Facial Inferences that Predict Voting Behavior. PLoS ONE, 3(10). DOI: 10.1371/journal.pone.0003666
- September 21, 2008
- 01:45 AM
- 719 views
mTOR, MAPK, and cancer
by Charles Daney in Science and Reason
Recent studies are making it increasingly apparent that cancer is really many different diseases – hundreds actually – in the sense that there are hundreds of distinct problems at a molecular level that can result in the symptoms of cancer in a large variety of tissue types. It is necessary to regard all these problems as distinct diseases, because different techniques will be necessary to deal effectively with each one. One of the things we are now understanding is that it is not si........ Read more »
Arkaitz Carracedo, Li Ma, Julie Teruya-Feldstein, Federico Rojo, Leonardo Salmena, Andrea Alimonti, Ainara Egia, Atsuo T. Sasaki, George Thomas, Sara C. Kozma.... (2008) Inhibition of mTORC1 leads to MAPK pathway activation through a PI3K-dependent feedback loop in human cancer. Journal of Clinical Investigation. DOI: 10.1172/JCI34739
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