Population expansion in the North African Late Pleistocene signalled by mitochondrial DNA haplogroup U6

Background <br/> The archaeology of North Africa remains enigmatic, with questions of population continuity versus discontinuity taking centre-stage. Debates have focused on population transitions between the bearers of the Middle Palaeolithic Aterian industry and the later Upper Palaeolithic populations of the Maghreb, as well as between the late Pleistocene and Holocene. <br/> Results Improved resolution of the mitochondrial DNA (mtDNA) haplogroup U6 phylogeny, by the screening of 39 new complete sequences, has enabled us to infer a signal of moderate population expansion using Bayesian coalescent methods. To ascertain the time for this expansion, we applied both a mutation rate accounting for purifying selection and one with an internal calibration based on four approximate archaeological dates: the settlement of the Canary Islands, the settlement of Sardinia and its internal population re-expansion, and the split between haplogroups U5 and U6 around the time of the first modern human settlement of the Near East. <br/> Conclusions <br/> A Bayesian skyline plot placed the main expansion in the time frame of the Late Pleistocene, around 20 ka, and spatial smoothing techniques suggested that the most probable geographic region for this demographic event was to the west of North Africa. A comparison with U6's European sister clade, U5, revealed a stronger population expansion at around this time in Europe. Also in contrast with U5, a weak signal of a recent population expansion in the last 5,000 years was observed in North Africa, pointing to a moderate impact of the late Neolithic on the local population size of the southern Mediterranean coast

Accelerometers can measure total and activity-specific energy expenditures in free-ranging marine mammals only if linked to time-activity budgets

Peer reviewedPostprin

Enhancement of antimicrobial activity of antibiotics and antifungals by the use of natural products from Pityrogramma calomelanos (L.) link

The ethanol extract and methanol fraction of Pityrogramma calomelanos (L.) link were evaluated for antibacterial, antifungal and modulatory activities against strains of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, C. krusei and C. tropicalis. The antimicrobial activity of the natural products was evaluated by the microdilution method associated or not with aminoglycosides and antifungals. The ethanol extract and methanol fraction of P. calomelanos showed good activity against S. aureus when associated with aminoglycosides and with benzoilmetronidazol against species of the genus Candida. These results indicate that P. calomelanos should be studied as a possible source of natural products to combat bacteria and fungi either directly or by modulating the mechanisms of resistance of these microorganisms, enhancing the antimicrobial activity of these drugs and combating microbial resistance

The Mythology of Game Theory

Non-cooperative game theory is at its heart a theory of cognition, specifically a theory of how decisions are made. Game theory\u27s leverage is that we can design different payoffs, settings, player arrays, action possibilities, and information structures, and that these differences lead to different strategies, outcomes, and equilibria. It is well-known that, in experimental settings, people do not adopt the predicted strategies, outcomes, and equilibria. The standard response to this mismatch of prediction and observation is to add various psychological axioms to the game-theoretic framework. Regardless of the differing specific proposals and results, game theory uniformly makes certain cognitive assumptions that seem rarely to be acknowledged, much less interrogated. Indeed, it is not widely understood that game theory is essentially a cognitive theory. Here, we interrogate those cognitive assumptions. We do more than reject specific predictions from specific games. More broadly, we reject the underlying cognitive model implicitly assumed by game theory

Generalized Species Sampling Priors with Latent Beta reinforcements

Many popular Bayesian nonparametric priors can be characterized in terms of exchangeable species sampling sequences. However, in some applications, exchangeability may not be appropriate. We introduce a {novel and probabilistically coherent family of non-exchangeable species sampling sequences characterized by a tractable predictive probability function with weights driven by a sequence of independent Beta random variables. We compare their theoretical clustering properties with those of the Dirichlet Process and the two parameters Poisson-Dirichlet process. The proposed construction provides a complete characterization of the joint process, differently from existing work. We then propose the use of such process as prior distribution in a hierarchical Bayes modeling framework, and we describe a Markov Chain Monte Carlo sampler for posterior inference. We evaluate the performance of the prior and the robustness of the resulting inference in a simulation study, providing a comparison with popular Dirichlet Processes mixtures and Hidden Markov Models. Finally, we develop an application to the detection of chromosomal aberrations in breast cancer by leveraging array CGH data.Comment: For correspondence purposes, Edoardo M. Airoldi's email is [email protected]; Federico Bassetti's email is [email protected]; Michele Guindani's email is [email protected] ; Fabrizo Leisen's email is [email protected]. To appear in the Journal of the American Statistical Associatio

Phenomenology of the Lense-Thirring effect in the Solar System

Recent years have seen increasing efforts to directly measure some aspects of the general relativistic gravitomagnetic interaction in several astronomical scenarios in the solar system. After briefly overviewing the concept of gravitomagnetism from a theoretical point of view, we review the performed or proposed attempts to detect the Lense-Thirring effect affecting the orbital motions of natural and artificial bodies in the gravitational fields of the Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of the impact of several sources of systematic uncertainties of dynamical origin to realistically elucidate the present and future perspectives in directly measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in Astrophysics and Space Science (ApSS). Some uncited references in the text now correctly quoted. One reference added. A footnote adde

Early pair housing increases solid feed intake and weight gains in dairy calves

Dairy calves have traditionally been kept in individual pens throughout the milk-feeding period. Social rearing is associated with increased solid feed intake and hence higher weight gains before and after weaning. Little is known about the effect of the age at which social housing begins. The aim of this study was to assess the effects of early versus late pairing on feeding behavior and weight gain before and after weaning. Holstein bull calves were reared individually (n=8 calves), or paired with another calf at 6 ± 3 d (n=8 pairs) or 43 ± 3 d of age (n=8 pairs). All calves were fed 8 L of milk/d for 4 wk, 6 L/d from 4 to 7 wk and then milk was reduced by 20%/d until calves were completely weaned at 8 wk of age. Calves were provided ad libitum access to calf starter and a total mixed ration (TMR). Body weight and feed intake were measured weekly from 3 to 10 wk of age. Intake of calf starter was significantly higher for the early-paired calves than for individually-reared and late-paired calves throughout the experimental period. At 10 wk of age, starter dry matter intake (DMI) averaged 2.20 ± 0.22 kg/d, 1.09 ± 0.25 kg/d and 1.26 ± 0.33 kg/d for early pair, late pair and individually housed calves, respectively. Intake of TMR did not differ among treatments, TMR dry matter intake (averaged 3.27 ± 0.72 kg/d, 3.08 ± 0.46 kg/d, and 2.89 ± 0.54 kg/d for the same three treatments). Calves in the early pair treatment also showed significantly higher average daily gain (ADG) over the experimental period (0.89 ± 0.04 kg/d versus 0.76 ± 0.04 kg/d and 0.73 ± 0.04 kg/d for the early paired, individual and late-paired calves, respectively). These results indicate that social housing soon after birth can increase weight gains and intake of solid feed

Decoherence in trapped ions due to polarization of the residual background gas

We investigate the mechanism of damping and heating of trapped ions associated with the polarization of the residual background gas induced by the oscillating ions themselves. Reasoning by analogy with the physics of surface electrons in liquid helium, we demonstrate that the decay of Rabi oscillations observed in experiments on 9Be+ can be attributed to the polarization phenomena investigated here. The measured sensitivity of the damping of Rabi oscillations with respect to the vibrational quantum number of a trapped ion is also predicted in our polarization model.Comment: 26 pdf pages with 5 figures, http://www.df.ufscar.br/~quantum

Neutralino relic density in supersymmetric GUTs with no-scale boundary conditions above the unification scale

We investigate SU(5) and SO(10) GUTs with vanishing scalar masses and trilinear scalar couplings at a scale higher than the unification scale. The parameter space of the models, further constrained by b-\tau Yukawa coupling unification, consists of a common gaugino mass and of \tan\beta. We analyze the low energy phenomenology, finding that A-pole annihilations of neutralinos and/or coannihilations with the lightest stau drive the relic density within the cosmologically preferred range in a significant region of the allowed parameter space. Implications for neutralino direct detection and for CERN LHC experiments are also discussed.Comment: 14 pages, 5 figures, JHEP style. Version accepted for publication in JHE

Schottky barrier heights at polar metal/semiconductor interfaces

Using a first-principle pseudopotential approach, we have investigated the Schottky barrier heights of abrupt Al/Ge, Al/GaAs, Al/AlAs, and Al/ZnSe (100) junctions, and their dependence on the semiconductor chemical composition and surface termination. A model based on linear-response theory is developed, which provides a simple, yet accurate description of the barrier-height variations with the chemical composition of the semiconductor. The larger barrier values found for the anion- than for the cation-terminated surfaces are explained in terms of the screened charge of the polar semiconductor surface and its image charge at the metal surface. Atomic scale computations show how the classical image charge concept, valid for charges placed at large distances from the metal, extends to distances shorter than the decay length of the metal-induced-gap states.Comment: REVTeX 4, 11 pages, 6 EPS figure