Genome-wide scan of copy number variation in late-onset Alzheimer's disease.

Alzheimer's disease is a complex and progressive neurodegenerative disease leading to loss of memory, cognitive impairment, and ultimately death. To date, six large-scale genome-wide association studies have been conducted to identify SNPs that influence disease predisposition. These studies have confirmed the well-known APOE epsilon4 risk allele, identified a novel variant that influences disease risk within the APOE epsilon4 population, found a SNP that modifies the age of disease onset, as well as reported the first sex-linked susceptibility variant. Here we report a genome-wide scan of Alzheimer's disease in a set of 331 cases and 368 controls, extending analyses for the first time to include assessments of copy number variation. In this analysis, no new SNPs show genome-wide significance. We also screened for effects of copy number variation, and while nothing was significant, a duplication in CHRNA7 appears interesting enough to warrant further investigation.

Experimental evaluation of evolution and coevolution as agents of ecosystem change in Trinidadian streams.

Evolution has been shown to be a critical determinant of ecological processes in some systems, but its importance relative to traditional ecological effects is not well known. In addition, almost nothing is known about the role of coevolution in shaping ecosystem function. Here, we experimentally evaluated the relative effects of species invasion (a traditional ecological effect), evolution and coevolution on ecosystem processes in Trinidadian streams. We manipulated the presence and population-of-origin of two common fish species, the guppy (Poecilia reticulata) and the killifish (Rivulus hartii). We measured epilithic algal biomass and accrual, aquatic invertebrate biomass, and detrital decomposition. Our results show that, for some ecosystem responses, the effects of evolution and coevolution were larger than the effects of species invasion. Guppy evolution in response to alternative predation regimes significantly influenced algal biomass and accrual rates. Guppies from a high-predation site caused an increase in algae relative to guppies from a low-predation site; algae effects were probably shaped by observed divergence in rates of nutrient excretion and algae consumption. Rivulus-guppy coevolution significantly influenced the biomass of aquatic invertebrates. Locally coevolved populations reduced invertebrate biomass relative to non-coevolved populations. These results challenge the general assumption that intraspecific diversity is a less critical determinant of ecosystem function than is interspecific diversity. Given existing evidence for contemporary evolution in these fish species, our findings suggest considerable potential for eco-evolutionary feedbacks to operate as populations adapt to natural or anthropogenic perturbations.

Death on a road (Dem. 23.53)

Scholarly consensus holds that a law quoted in Demosthenes (23.53) permitted one to kill a highway robber who had lain in ambush and attacked one on a road. But the relevant phrase says nothing explicit about ambush. Modern interpretation derives from Harpocration and other ancient authorities. It is argued here that they were mistaken and that the phrase referred to those who inadvertently killed a fellow traveler while overtaking on a road.' The new interpretation may offer another way to think about the encounter between Oedipus and Laius.

King Democracy: Do Democratic Nations Mitigate Conflict Over Transboundary Freshwater Resources Better Than Other Nations?

The prospect of water wars and conflict over water are ideas that are frequently dramatized in media and also studied by scholars. It is well-established that bona fide wars are not started over water resources, but conflict over water does exist and is not well understood. One would suppose, as scholars often do, that dyads composed of two democratic nations would be the best at mitigating conflict and promoting cooperation over freshwater resources. General conflict research supports that supposition, as does the argument that democracies must be best at avoiding conflicts over resources because they excel at distributing public goods. This study provides empirical evidence showing how interstate dyads composed of various governance types conflict and cooperate over general water and water quantity issues relative to each other. After evaluating the water conflict mitigating ability of democratic-democratic, democratic-autocratic, and autocratic-autocratic dyads, this study found that democracy-autocracy dyads are less likely to cooperate over general water issues and water quantity issues than the other two dyad types. Nothing certain can be said about how the three dyad types compare to each other in terms of likelihood to conflict over water quantity issues. However, two-autocracy dyads seem to be most likely to cooperate over water quantity issues. These findings support the established belief that democratic-autocratic pairs struggle to cooperate while also encouraging greater scrutiny of the belief that democracies must be best at cooperating over water resources.