Inherent-Structure Dynamics and Diffusion in Liquids

The self-diffusion constant D is expressed in terms of transitions among the local minima of the potential (inherent structure, IS) and their correlations. The formulae are evaluated and tested against simulation in the supercooled, unit-density Lennard-Jones liquid. The approximation of uncorrelated IS-transition (IST) vectors, D_{0}, greatly exceeds D in the upper temperature range, but merges with simulation at reduced T ~ 0.50. Since uncorrelated IST are associated with a hopping mechanism, the condition D ~ D_{0} provides a new way to identify the crossover to hopping. The results suggest that theories of diffusion in deeply supercooled liquids may be based on weakly correlated IST.Comment: submitted to PR

A cost-reducing extracorporeal membrane oxygenation (ECMO) program model: a single institution experience.

BACKGROUND: The worldwide demand for ECMO support has grown. Its provision remains limited due to several factors (high cost, complicated technology, lack of expertise) that increase healthcare cost. Our goal was to assess if an intensive care unit (ICU)-run ECMO model without continuous bedside perfusionists would decrease costs while maintaining patient safety and outcomes. METHOD: A new ECMO program was implemented in 2010, consisting of dedicated ICU multidisciplinary providers (ICU-registered nurses, mid-level providers and intensivists). In year one, we introduced an education platform, new technology and dedicated space. In year two, continuous bedside monitoring by perfusionists was removed and new management algorithms designating multidisciplinary providers as first responders were established. The patient safety and cost benefit from the removal of the continuous bedside monitoring of the perfusionists of this new ECMO program was retrospectively reviewed and compared. RESULTS: During the study period, 74 patients (28 patients in year 1 and 46 patients in year 2) were placed on ECMO (mean days: 8 ± 5.7). The total annual hospital expenditure for the ECMO program was significantly reduced in the new model ($234,000 in year 2 vs.$600,264 in year 1), showing a 61% decrease in cost. This cost decrease was attributed to a decreased utilization of perfusion services and the introduction of longer lasting and more efficient ECMO technology. We did not find any significant changes in registered nurse ratios or any differences in outcomes related to ICU safety events. CONCLUSION: We demonstrated that the ICU-run ECMO model managed to lower hospital cost by reducing the cost of continuous bedside perfusion support without a change in outcomes

Desarrollo con FPGAs en GNU/Linux

GNU/Linux (la combinación del kernel Linux y herramientas del proyecto GNU) es uno de los ejemplos más prominentes de Software Libre. El Software Libre es la denominación del software que respeta la libertad de los usuarios. Una vez obtenido puede ser usado, copiado, estudiado, cambiado y redistribuido libremente. Las herramientas Libres que presentaremos para el desarrollo con FPGAs (Field Programmable Gate Array), están lo suficientemente maduras para su uso en ámbitos educativos y en proyectos de mediana envergadura. El uso de Software Libre y la utilización de estándares, promueve la independencia tecnológica, la portabilidad de lo desarrollado y la posibilidad de ser abordado por cualquiera con acceso a una PC sin la necesidad del pago de licencias.Sección: Tutoriales – ResúmenesCentro de Técnicas Analógico-Digitale

Disrupted in schizophrenia 1 (DISC1) L100P mutants have impaired activity-dependent plasticity in vivo and in vitro

Major neuropsychiatric disorders are genetically complex but share overlapping etiology. Mice mutant for rare, highly penetrant risk variants can be useful in dissecting the molecular mechanisms involved. The gene disrupted in schizophrenia 1 (DISC1) has been associated with increased risk for neuropsychiatric conditions. Mice mutant for Disc1 display morphological, functional and behavioral deficits that are consistent with impairments observed across these disorders. Here we report that Disc1 L100P mutants are less able to reorganize cortical circuitry in response to stimulation in vivo. Molecular analysis reveals that the mutants have a reduced expression of PSD95 and pCREB in visual cortex and fail to adjust expression of such markers in response to altered stimulation. In vitro analysis shows that mutants have impaired functional reorganization of cortical neurons in response to selected forms of neuronal stimulation, but there is no altered basal expression of synaptic markers. These findings suggest that DISC1 has a critical role in the reorganization of cortical plasticity and that this phenotype becomes evident only under challenge, even at early postnatal stages. This result may represent an important etiological mechanism in the emergence of neuropsychiatric disorders

Influence of shock wave propagation on dielectric barrier discharge plasma actuator performance

Interest in plasma actuators as active flow control devices is growing rapidly due to their lack of mechanical parts, light weight and high response frequency. Although the flow induced by these actuators has received much attention, the effect that the external flow has on the performance of the actuator itself must also be considered, especially the influence of unsteady high-speed flows which are fast becoming a norm in the operating flight envelopes. The primary objective of this study is to examine the characteristics of a dielectric barrier discharge (DBD) plasma actuator when exposed to an unsteady flow generated by a shock tube. This type of flow, which is often used in different studies, contains a range of flow regimes from sudden pressure and density changes to relatively uniform high-speed flow regions. A small circular shock tube is employed along with the schlieren photography technique to visualize the flow. The voltage and current traces of the plasma actuator are monitored throughout, and using the well-established shock tube theory the change in the actuator characteristics are related to the physical processes which occur inside the shock tube. The results show that not only is the shear layer outside of the shock tube affected by the plasma but the passage of the shock front and high-speed flow behind it also greatly influences the properties of the plasma

The long journey to a Systems Biology of neuronal function

Computational neurobiology was born over half a century ago, and has since been consistently at the forefront of modelling in biology. The recent progress of computing power and distributed computing allows the building of models spanning several scales, from the synapse to the brain. Initially focused on electrical processes, the simulation of neuronal function now encompasses signalling pathways and ion diffusion. The flow of quantitative data generated by the "omics" approaches, alongside the progress of live imaging, allows the development of models that will also include gene regulatory networks, protein movements and cellular remodelling. A systems biology of brain functions and disorders can now be envisioned. As it did for the last half century, neuroscience can drive forward the field of systems biology

Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV

A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse momentum, using a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected particle and one or two jets

Loss of Arc renders the visual cortex impervious to the effects of sensory experience or deprivation

A myriad of mechanisms have been suggested to account for the full richness of visual cortical plasticity. We found that visual cortex lacking Arc is impervious to the effects of deprivation or experience. Using intrinsic signal imaging and chronic visually evoked potential recordings, we found that Arc−/− mice did not exhibit depression of deprived-eye responses or a shift in ocular dominance after brief monocular deprivation. Extended deprivation also failed to elicit a shift in ocular dominance or open-eye potentiation. Moreover, Arc−/− mice lacked stimulus-selective response potentiation. Although Arc−/− mice exhibited normal visual acuity, baseline ocular dominance was abnormal and resembled that observed after dark-rearing. These data suggest that Arc is required for the experience-dependent processes that normally establish and modify synaptic connections in visual cortex.Howard Hughes Medical InstituteNational Science Foundation (U.S.

X-ray emission from the Sombrero galaxy: discrete sources

We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30 kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray binaries (LMXBs). We quantify the differential luminosity functions (LFs) for both the detected GC and field LMXBs, whose power-low indices (~1.1 for the GC-LF and ~1.6 for field-LF) are consistent with previous studies for elliptical galaxies. With precise sky positions of the GCs without a detected X-ray source, we further quantify, through a fluctuation analysis, the GC LF at fainter luminosities down to 1E35 erg/s. The derived index rules out a faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent findings in several elliptical galaxies and the bulge of M31. On the other hand, the 2-6 keV unresolved emission places a tight constraint on the field LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101 sources in the halo of Sombrero. The presence of these sources cannot be interpreted as galactic LMXBs whose spatial distribution empirically follows the starlight. Their number is also higher than the expected number of cosmic AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray surveys. We suggest that either the cosmic X-ray background is unusually high in the direction of Sombrero, or a distinct population of X-ray sources is present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns