543 research outputs found

    Search for new physics in events with opposite-sign dileptons and missing transverse energy with the CMS experiment

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    The results of a search for new physics in events with two opposite-sign isolated electrons or muons, hadronic activity, and missing transverse energy in the final state are presented. The results are based on analysis of a data sample with a corresponding integrated luminosity of 0.98 fb-1 produced in pp collisions at a center-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. No evidence for an event yield beyond Standard-Model expectations is found, and constraints on supersymmetric models are deduced from these observations.Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011), Paris, France, November 14-18 2011, 3 pages, 3 figure

    Response of moist and dry processes in atmospheric blocking to climate change

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    Weather extremes are often associated with atmospheric blocking, but how the underlying physical processes leading to blocking respond to climate change is not yet fully understood. Here we track blocks as upper-level negative potential vorticity (PV) anomalies and apply a Lagrangian analysis to 100 years of present-day (∼2000) and future (∼2100, under the RCP8.5 scenario) climate simulations restarted from the Community Earth System Model–Large Ensemble Project runs (CESM-LENS) to identify different physical processes and quantify how their relative importance changes in a warmer and more humid climate. The trajectories reveal two contrasting airstreams that both contribute to the formation and maintenance of blocking: latent heating in strongly ascending airstreams (moist processes) and quasi-adiabatic flow near the tropopause with weak radiative cooling (dry processes). Both are reproduced remarkably well when compared against ERA-Interim reanalysis, and their relative importance varies regionally and seasonally. The response of blocks to climate change is complex and differs regionally, with a general increase in the importance of moist processes due to stronger latent heating (+1 K in the median over the Northern Hemisphere) and a larger fraction (+15%) of strongly heated warm conveyor belt air masses, most pronounced over the storm tracks. Future blocks become larger (+7%) and their negative PV anomaly slightly intensifies (+0.8%). Using a Theil–Sen regression model, we propose that the increase in size and intensity is related to the increase in latent heating, resulting in stronger cross-isentropic transport of air with low PV into the blocking anticyclones. Our findings provide evidence that moist processes become more important for the large-scale atmospheric circulation in the midlatitudes, with the potential for larger and more intense blocks

    Performance unter Ironieverdacht/ Performance under Suspicion of Irony

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    The θ\theta-θ\theta Diagram: Transforming pulsar scintillation spectra to coordinates on highly anisotropic interstellar scattering screens

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    We introduce a novel analysis technique for pulsar secondary spectra. The power spectrum of pulsar scintillation (referred to as the "secondary spectrum") shows differential delays and Doppler shifts due to interference from multi-path propagation through the interstellar medium. We develop a transformation which maps these observables to angular coordinates on a single thin screen of phase-changing material. This transformation is possible without degeneracies in the case of a one-dimensional distribution of images on this screen, which is often a successful description of the phenomenon. The double parabolic features of secondary spectra are transformed into parallel linear features, whose properties we describe in detail. Furthermore, we introduce methods to measure the curvature parameter and the field amplitude distribution of images by applying them to observations of PSR B0834+06. Finally, we extend this formalism to two-dimensional distributions of images on the interstellar screen.Comment: 11 pages, 14 figures, 1 table, v2: matches accepted versio

    Sialic Acid Utilisation and Synthesis in the Neonatal Rat Revisited

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    Background: Milk is the sole source of nutrients for neonatal mammals and is generally considered to have co-evolved with the developmental needs of the suckling newborn. One evolutionary conserved constituent of milk and present on many glycoconjugates is sialic acid. The brain and colon are major sites of sialic acid display and together with the liver also of synthesis. Methodology/Principal Findings: In this study we examined in rats the relationship between the sialic acid content of milk and the uptake, utilization and synthesis of sialic acid in suckling pups. In rat milk sialic acid was found primarily as 39sialyllactose and at highest levels between 3 and 10 days postpartum and that decreased towards weaning. In the liver of suckling pups sialic acid synthesis paralleled the increase in milk sialic acid reaching and keeping maximum activity from postnatal day 5 onwards. In the colon, gene expression profiles suggested that a switch from sialic acid uptake and catabolism towards sialic acid synthesis and utilization occurred that mirrored the change of sialic acid in milk from high to low expression. In brain sialic acid related gene expression profiles did not change to any great extent during the suckling period. Conclusions/Significance: Our results support the views that (i) when milk sialic acid levels are high, in the colon this sialic acid is catabolized to GlcNAc that in turn may be used as such or used as substrate for sialic acid synthesis and (ii) when milk sialic acid levels are low the endogenous sialic acid synthetic machinery in colon is activated

    Using single‐plant‐omics in the field to link maize genes to functions and phenotypes

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    Most of our current knowledge on plant molecular biology is based on experiments in controlled laboratory environments. However, translating this knowledge from the laboratory to the field is often not straightforward, in part because field growth conditions are very different from laboratory conditions. Here, we test a new experimental design to unravel the molecular wiring of plants and study gene-phenotype relationships directly in the field. We molecularly profiled a set of individual maize plants of the same inbred background grown in the same field and used the resulting data to predict the phenotypes of individual plants and the function of maize genes. We show that the field transcriptomes of individual plants contain as much information on maize gene function as traditional laboratory-generated transcriptomes of pooled plant samples subject to controlled perturbations. Moreover, we show that field-generated transcriptome and metabolome data can be used to quantitatively predict individual plant phenotypes. Our results show that profiling individual plants in the field is a promising experimental design that could help narrow the lab-field gap

    Development of a phantom to modulate the maternal and fetal pulse curve for pulse oximetry measurements

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    For getting reliable information about the state of health from the fetus and the mother during labor and delivery, a fetal pulse oximeter is being developed. This paper describes the development of a special phantom to verify the algorithms for separating the weak fetal from the dominant maternal optical signal. To reach a realistic behavior it is necessary for two circulations to be controlled independently. Inspired by the natural blood circulation behavior, a RC-System with fixed resistance and capacity was created. Pumping a liquid with a roller pump into the tubes widens them. The digital signal processor (DSP) controls the expansion of the tube diameter by modifying the rotation velocity of the pump for active regulation. Therefore a soft and good enlargeable material was used. The measured values of the pressure sensor enabled active feedback for motor control The determined system characteristics are used to adapt the given pulse curve to the real system behavior. Via a LabView interface it is possible to change curve parameters like amplitude and frequency. The goal was to replicate the pulsation of the blood vessels like in the abdomen of a pregnant woman. Changing the parameters influences the modulation of the signal under consideration of the transfer function. With this phantom it is possible to simulate different scenarios, for example different states of pregnancy or pathogen indications
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