Conduction Channels of One-Atom Zinc Contacts

We have determined the transmission coefficients of atomic-sized Zn contacts using a new type of breakjunction which contains a whisker as a central bridge. We find that in the last conductance plateau the transport is unexpectedly dominated by a well-transmitting single conduction channel. We explain the experimental findings with the help of a tight-binding model which shows that in an one-atom Zn contact the current proceeds through the 4s and 4p orbitals of the central atom.Comment: revtex4, 5 pages, 5 figure

Altimetry, gravimetry, GPS and viscoelastic modeling data for the joint inversion for glacial isostatic adjustment in Antarctica (ESA STSE Project REGINA)

The poorly known correction for the ongoing deformation of the solid Earth caused by glacial isostatic adjustment (GIA) is a major uncertainty in determining the mass balance of the Antarctic ice sheet from measurements of satellite gravimetry and to a lesser extent satellite altimetry. In the past decade, much progress has been made in consistently modeling ice sheet and solid Earth interactions; however, forward-modeling solutions of GIA in Antarctica remain uncertain due to the sparsity of constraints on the ice sheet evolution, as well as the Earth's rheological properties. An alternative approach towards estimating GIA is the joint inversion of multiple satellite data – namely, satellite gravimetry, satellite altimetry and GPS, which reflect, with different sensitivities, trends in recent glacial changes and GIA. Crucial to the success of this approach is the accuracy of the space-geodetic data sets. Here, we present reprocessed rates of surface-ice elevation change (Envisat/Ice, Cloud,and land Elevation Satellite, ICESat; 2003–2009), gravity field change (Gravity Recovery and Climate Experiment, GRACE; 2003–2009) and bedrock uplift (GPS; 1995–2013). The data analysis is complemented by the forward modeling of viscoelastic response functions to disc load forcing, allowing us to relate GIA-induced surface displacements with gravity changes for different rheological parameters of the solid Earth. The data and modeling results presented here are available in the PANGAEA database (https://doi.org/10.1594/PANGAEA.875745). The data sets are the input streams for the joint inversion estimate of present-day ice-mass change and GIA, focusing on Antarctica. However, the methods, code and data provided in this paper can be used to solve other problems, such as volume balances of the Antarctic ice sheet, or can be applied to other geographical regions in the case of the viscoelastic response functions. This paper presents the first of two contributions summarizing the work carried out within a European Space Agency funded study: Regional glacial isostatic adjustment and CryoSat elevation rate corrections in Antarctica (REGINA)

Impact of Extreme Heat Events on Emergency Department Visits in North Carolina (2007–2011)

Extreme heat is the leading cause of w eather-related mortality in the U.S. Extreme heat also affects human health through heat stress and can exacerbate underlying medical conditions that lead to increased morbidity and mortality. In this study, data on emergency department (ED) visits for heat-related illness (HRI) and other selected diseases were analyzed during three heat events across North Carolina from 2007 to 2011. These heat events were identified based on the issuance and verification of heat products from local National Weather Service forecast offices (i.e. Heat Advisory, Heat Watch, and Excessive Heat Warning). The observed number of ED visits during these events were compared to the expected number of ED visits during several control periods to determine excess morbidity resulting from extreme heat. All recorded diagnoses were analyzed for each ED visit, thereby providing insight into the specific pathophysiological mechanisms and underlying health conditions associated with exposure to extreme heat. The most common form of HRI was heat exhaustion, while the percentage of visits with heat stroke was relatively low (65 years of age) were at greatest risk for HRI during the early summer heat event (8.9 visits per 100,000), while young and middle age adults (18–44 years of age) were at greatest risk during the mid-summer event (6.3 visits per 100,000). Many of these visits were likely due to work-related exposure. The most vulnerable demographic during the late summer heat event was adolescents (15–17 years of age), which may relate to the timing of organized sports. This demographic also exhibited the highest visit rate for HRI among all three heat events (10.5 visits per 100,000). Significant increases (p < 0.05) in visits with cardiovascular and cerebrovascular diseases were noted during the three heat events (3–8 %). The greatest increases were found in visits with hypotension during the late summer event (23 %) and sequelae during the early summer event (30 %), while decreases were noted for visits with hemorrhagic stroke during the middle and late summer events (13–24 %) and for visits with aneurysm during the early summer event (15 %). Significant increases were also noted in visits with respiratory diseases (5–7 %). The greatest increases in this category were found in visits with pneumonia and influenza (16 %), bronchitis and emphysema (12 %), and COPD (14 %) during the early summer event. Significant increases in visits with nervous system disorders were also found during the early summer event (16 %), while increases in visits with diabetes were noted during the mid-summer event (10 %)

Mountain Pygmies of Western New Guinea: A Morphological and Molecular Approach

The presence of pygmy or pygmoid groups among New Guinea populations has been the object of scientific interest since the end of the nineteenth century. Morphological and molecular data are used here to study western New Guinea population variability, focusing in particular on two pygmoid groups living in the eastern fringe highlands of Papua: the Una and the Ketengban. Various kinds of anthropometric data are examined, as well as height, weight, and body mass index, to carry out comparisons with nearby ethnic groups living in the highland and lowland regions. The Ketengban data were also compared with other data recorded 20 years before. The results of previous research on the sequencing of the mitochondrial DNA hypervariable segment 1 region and nuclear DNA nonrecombining Y-chromosome polymorphisms are presented. Both morphological and molecular studies involve adult subjects of both genders, representative of the same ethnic groups and/ or geographic regions. The pygmoid groups turn out to be significantly different from all other study groups, due to their small size, as confirmed by analysis of variance, although significant height and weight increments are observed with respect to those previously recorded. However, putative neutral genetic variation estimated from mitochondrial DNA and Y-chromosome markers support a recent shared common history between these pygmoid populations and the other central Papua groups (except for the Dani-Lani). These findings suggest that the short-stature phenotype is an independent secondary adaptation, possibly driven by an iodine-deficient environment, which leaves the potential for further investigations

Rewiring Neural Interactions by Micro-Stimulation

Plasticity is a crucial component of normal brain function and a critical mechanism for recovery from injury. In vitro, associative pairing of presynaptic spiking and stimulus-induced postsynaptic depolarization causes changes in the synaptic efficacy of the presynaptic neuron, when activated by extrinsic stimulation. In vivo, such paradigms can alter the responses of whole groups of neurons to stimulation. Here, we used in vivo spike-triggered stimulation to drive plastic changes in rat forelimb sensorimotor cortex, which we monitored using a statistical measure of functional connectivity inferred from the spiking statistics of the neurons during normal, spontaneous behavior. These induced plastic changes in inferred functional connectivity depended on the latency between trigger spike and stimulation, and appear to reflect a robust reorganization of the network. Such targeted connectivity changes might provide a tool for rerouting the flow of information through a network, with implications for both rehabilitation and brain–machine interface applications

Stochastic evolution of four species in cyclic competition

We study the stochastic evolution of four species in cyclic competition in a well mixed environment. In systems composed of a finite number $N$ of particles these simple interaction rules result in a rich variety of extinction scenarios, from single species domination to coexistence between non-interacting species. Using exact results and numerical simulations we discuss the temporal evolution of the system for different values of $N$, for different values of the reaction rates, as well as for different initial conditions. As expected, the stochastic evolution is found to closely follow the mean-field result for large $N$, with notable deviations appearing in proximity of extinction events. Different ways of characterizing and predicting extinction events are discussed.Comment: 19 pages, 6 figures, submitted to J. Stat. Mec

Pasado, presente y futuro del búfalo en Argentina

El búfalo comenzó a ser introducido al país a comienzo el siglo XX, mediante la importación razas Mediterránea, Murrah y Jafarabadi. En la actualidad la población bubalina alcanzó las de 87.711 cabezas y se encuentran distribuidas en 20 de las 23 provincias que componen el territorio nacional. El 80 % de la población de búfalos se encuentran en el nordeste argentino. Siendo las provincias de Formosa y Corrientes las que cuentan con la mayores poblaciones bubalinas. Existen en el país 8 millones de hectáreas aptas para soportar una carga de 4 millones de búfalos.The buffalo began to be introduced to the country in the early twentieth century, by importing Mediterranean, Murrah and Jafarabadi breeds. Today buffalo population reached 87.711 heads, which are distributed in 20 out of the 23 provinces that conforms the country. The 80% of the population of buffaloes is found in northeastern region, being the provinces of Formosa and Corrientes those with the largest buffalo population. The country has 8 million hectares suitable to withstand a load of 4 million buffaloes.Fil: Crudeli, G. A.. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias; ArgentinaFil: Patiño, E. M.. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias; ArgentinaFil: Maldonado Vargas, P.. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias; ArgentinaFil: Konrad, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias; Argentin

Two modes of evolution shape bacterial strain diversity in the mammalian gut for thousands of generations

How and at what pace bacteria evolve when colonizing healthy hosts remains unclear. Here, by monitoring evolution for more than six thousand generations in the mouse gut, we show that the successful colonization of an invader Escherichia coli depends on the diversity of the existing microbiota and the presence of a closely related strain. Following colonization, two modes of evolution were observed: one in which diversifying selection leads to long-term coexistence of ecotypes and a second in which directional selection propels selective sweeps. These modes can be quantitatively distinguished by the statistics of mutation trajectories. In our experiments, diversifying selection was marked by the emergence of metabolic mutations, and directional selection by acquisition of prophages, which bring their own benefits and costs. In both modes, we observed parallel evolution, with mutation accumulation rates comparable to those typically observed in vitro on similar time scales. Our results show how rapid ecotype formation and phage domestication can be in the mammalian gut.info:eu-repo/semantics/publishedVersio