Infanticide and infant defence by males--modelling the conditions in primate multi-male groups

Infanticide by primate males was considered rare if groups contain more than one adult male because, owing to lower paternity certainty, a male should be less likely to benefit from infanticide. Guided by recent evidence for strong variation of infanticide in primate multi-male groups, we modelled the conditions for when infanticide should occur for a group with a resident and an immigrant male. Setting the parameters (e.g. infant mortality, reduction of interbirth interval, life-time reproductive success, genetic representation) to fit the conditions most commonly found in nature, we develop a game-theoretic model to explore the influence of age and dominance on the occurrence of infanticide and infant defence. Male age strongly impacts the likelihood of an attack which is modified by the father's defence. If the new male is dominant he is likely to attack under most circumstances whereas a subordinate male will only attack if the father does not defend. These model scenarios fit the conditions under which infanticide is known to occur in primate multi-male groups and offer an explanation why infanticide is common in some multi-male groups and rare in others. Overall, the benefits for infanticidal males are strongly governed by a reduced interbirth interval while advantages via improved genetic representation in the gene pool contribute but a minor fraction

The chlorination of acetone.

This problem originated in an attempt to make methyl glyoxal in quantity. Several methods of making methyl glyoxal are mentioned in the literature but in none of them is acetone used as a starting point. Since this seemed a new field it was decided to chlorinate acetone hoping to obtain some product which might be easily converted into methyl glyoxal. Technical acetone was purified and dry chlorine was passed through this warm acetone in the presence of sunlight. During the process three distinct steps were noticed in the reaction. The first step was completed in the first half hour. During this time the acetone was held at the temperature of a boiling water bath and the chlorine was rapidly absorbed with an evolution of hydrochloric acid. At the end of this time the second step in the process set in, which lasted for two hours. Throughout this period no hydrochloric acid was evolved. The chlorine seemed to be simply absorbed with a marked heat of reaction. During the first half hour of this period the water bath was retained, but after that it was noticed that the heat of reaction was sufficient to keep the temperature up to 80 degrees Celsius. This seemed to be the critical temperature for this step of the reaction, for whenever the temperature exceeded 80 degrees Celsius a violent reaction occurred with a flame. As the heat of reaction was so intense during this step it was frequently necessary to cool the reaction mixture

Forecast of Total Electron Content over Europe for disturbed ionospheric Conditions

A general picture of the occurrence of ionospheric storms as function of local time, season and location is known from numerous studies over the past 50 years. Nevertheless, it is not yet possible to say how the ionosphere will actually respond to a given space weather event because the measurements of the onset time, location of maximum perturbation, amplitude and type of storm (positive or negative) deviate much from the climatology. However, statistical analyses of numerous storm events observed in the Total Electron Content (TEC) since 1995 enable to estimate and predict a most probable upcoming perturbed TEC over Europe based on forecasts of geomagnetic activity. A first approach will be presented here. The forecast of perturbed TEC is part of the Forecast System Ionosphere build under the umbrella of the FP7 project AFFECTS∗ (Advanced Forecast For Ensuring Communication Through Space). It aims to help users mitigating the impact on communication system

Quantum Quench of an Atomic Mott Insulator

We study quenches across the Bose-Hubbard Mott-insulator-to-superfluid quantum phase transition using an ultra-cold atomic gas trapped in an optical lattice. Quenching from the Mott insulator to superfluid phase is accomplished by continuously tuning the ratio of Hubbard tunneling to interaction energy. Excitations of the condensate formed after the quench are measured using time-of-flight imaging. We observe that the degree of excitation is proportional to the fraction of atoms that cross the phase boundary, and that the quantity of excitations and energy produced during the quench have a power-law dependence on the quench rate. These phenomena suggest an excitation process analogous to the Kibble-Zurek (KZ) mechanism for defect generation in non-equilibrium classical phase transitions

Atmospheric moisture transport and its impact on the water cycle over Alaska and Hawaii: the roles of the Pacific Decadal Oscillation and El Nino

Thesis (M.S.) University of Alaska Fairbanks, 2014Precipitation over the North Pacific can fluctuate under climate patterns such as the Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillation (ENSO). In order to better understand the role which these climatic patterns play in the North Pacific water budgets and pathways, we employed the Community Atmosphere Model 5.0 (CAM) and conducted sensitivity experiments to examine how atmospheric moisture convergence and moisture transport respond to sea surface temperature (SST) anomalies associated with the PDO and ENSO phase transitions. We have found that changes in transient moisture transport, as the PDO phase shifts from cool to warm, are due to increases in specific humidity and decreases in wind speeds over Alaska and the North Pacific. Additionally, increases in moisture convergence, specific humidity, and wind speeds and decreases in transient moisture transport are seen over the North Pacific during El Niño events compared to La Niña events

Early Warning of ionospheric disturbances for GNSS users

Temporal and spatial gradients in the ionosphere can cause major threats on communication and navigation satellite systems, because the propagation of transionospheric radio signals is influenced by the ionospheric electron content. Space weather events are often the source of strong ionospheric disturbances. Forecasting ionospheric perturbations related to space weather events is therefore a crucial task being of special interest for GNSS users. The climatology of ionospheric storms seen in the Total Electron Content (TEC) over Europe as a response of the ionosphere towards Earth oriented space weather events is well known. It depends on season, elapsed time from event arrival, location and local time. However, the deviation of a single storm to the mean behavior can be large. A good correlation between strength of the ionospheric storm, i.e. the maximum deviation of the TEC to 27 day median, to solar wind or geomagnetic activity indices is hard to define. Hence forecasting TEC for disturbed conditions is a challenging task. However, the storm climatology and comprehensive correlation studies allow forecasting of the most probable TEC perturbation amplitude for the European region. GNSS users are in need of information about arriving threads due to space weather events as early as possible. Therefore, an Early Warning message for GNSS users has been developed at the DLR within the FP7-Project AFFECTS. It provides information about Earth endangering space weather events to interested GNSS users up to two days before their arrival. Additional information are now added by a second warning message distributed thirty minutes before arrival at Earth giving more specific information like exact arrival time, forecasts of geomagnetic indices, approximate TEC perturbation and range error for the European region. An overview on the Early Warning for GNSS user service provided by DLR is presented in this paper

Structure and Activation Mechanism of the Drosophila Initiator Caspase Dronc

Activation of an initiator caspase is essential to the execution of apoptosis. The molecular mechanisms by which initiator caspases are activated remain poorly understood. Here we demonstrate that the autocatalytic cleavage of Dronc, an important initiator caspase in Drosophila, results in a drastic enhancement of its catalytic activity in vitro. The autocleaved Dronc forms a homodimer, whereas the uncleaved Dronc zymogen exists exclusively as a monomer. Thus the autocatalytic cleavage in Dronc induces its stable dimerization, which presumably allows the two adjacent monomers to mutually stabilize their active sites, leading to activation. Crystal structure of a prodomain-deleted Dronc zymogen, determined at 2.5 Å resolution, reveals an unproductive conformation at the active site, which is consistent with the observation that the zymogen remains catalytically inactive. This study revealed insights into mechanism of Dronc activation, and in conjunction with other observations, suggests diverse mechanisms for the activation of initiator caspases

Why has economic shrinking receded in Latin America? A social capability approach

Episodes of economic shrinking have declined since the 1980s in Latin America and the Caribbean (LAC). This paper asks why. We propose that the reduction in the frequency and rate of shrinking reveals the dynamic transition from being natural states towards becoming open access societies. To provide empirical support to the argument, we rest on the notion of social capabilities. Hence, societies that invest in their social capabilities are more likely to reduce the frequency of shrinking and become better off in the long run. Using survival models, we test three capabilities (transformative, distributive and regulative) that, we argue, reflect an increase in the resilience to economic shrinking. The results suggest that the transformative capability has not lowered the risk of shrinking in the region. Neither has the distributive capability despite the increases in productive employment during the 2000s. In contrast, regulative capability seems to reduce the risk of shrinking. We conclude that the institutional transformations in LAC are part of the explanation of why economic shrinking has receded. Compared to previous decades, this is an essential step towards open access societies. However, the persistent dependence on a few natural resources seems to hinder progressive transformation and remains a menace to sustainable catching up of the countries in the region