489 research outputs found
Search for a massive resonance decaying to qV/VV/VH in hadronic final states
Two searches for massive resonances decaying into qV/VV/VH final states are presented, in which V denotes W, Z bosons, and H denotes Higgs boson.
The data analyzed corresponds to an integrated luminosity of 19.7 fb−1 collected by the CMS detector in proton-proton collisions at √s = 8 TeV. The cutting edge jet substructure algorithms are used to distinguish V and H boson jets from the standard model QCD quark/gluon jets background.
Exclusion limits are set at a confidence level of 95% on the production cross sections of: (i) excited quark resonances q* decaying to qW and qZ for masses less than 3.2 TeV and 2.9 TeV, respectively, (ii) a Randall–Sundrum graviton decaying into WW for masses below 1.2 TeV, and (iii) a heavy partner of the W boson W′ decaying into WZ for masses less than 1.7 TeV. In HVT model scenario B, resonance masses are excluded for W′ in the interval [1.0, 1.6] TeV, for Z′ in the intervals [1.0, 1.1] and [1.3,1.5] TeV, and for mass-degenerate W′ and Z′ in the interval [1.0, 1.7] TeV. A model with a bulk graviton that decays into WW or ZZ bosons is also studied
Identifying boosted new physics with non-isolated leptons
We demonstrate the utility of leptons which fail standard isolation criteria
in searches for new physics at the LHC. Such leptons can arise in any event
containing a highly boosted particle which decays to both leptons and quarks.
We begin by considering multiple extensions to the Standard Model which
primarily lead to events with non-isolated leptons and are therefore missed by
current search strategies. We emphasize the failure of standard isolation
variables to adequately discriminate between signal and SM background for any
value of the isolation cuts. We then introduce a new approach which makes use
of jet substructure techniques to distinguish a broad range of signals from QCD
events. We proceed with a simulated, proof-of-principle search for R-parity
violating supersymmetry to demonstrate both the experimental reach possible
with the use of non-isolated leptons and the utility of new substructure
variables over existing techniquesComment: 15 pages plus references, 11 figures; references adde
Atmospheric turbulence and land - atmosphere energy transfer characteristics in the surface layer of the Northern slope of Mt. Qomolangma area : abstract
Based on the turbulent data collected at Quzong site, on the northern slope of Mt. Qomolangma, from April 2005 to March 2006, macro-scale turbulent statistical characteristics and land-atmosphere energy transfer before and after the onset of southwest monsoon were acquired by the eddy correlation method. It was found that Monin-Obukhov similarity theory is applicable for Mt. Qomolangma area. The relationship between normalized wind speed standard deviation and atmospheric stability, variances of normalized temperature and humidity standard deviation with atmospheric stability were simulated in the study. It was also found that energy balance components (net radiation flux, sensible heat flux, latent heat flux and soil heat flux) and surface heating filed had evident diurnal and seasonal changes. Especially under the influence of southwest monsoon, the sensible heat flux and latent heat flux in Quzong area have evident opposite changing trends. The variation characteristics of other surface parameters (surface reflectance and Bowen ratio) is very clear before and after the breakout of southwest monsoon
A Deep Spatiotemporal Attention Network for Mild Cognitive Impairment Identification
Mild cognitive impairment (MCI) is a nervous system disease, and its clinical status can be used as an early warning of Alzheimer's disease (AD). Subtle and slow changes in brain structure between patients with MCI and normal controls (NCs) deprive them of effective diagnostic methods. Therefore, the identification of MCI is a challenging task. The current functional brain network (FBN) analysis to predict human brain tissue structure is a new method emerging in recent years, which provides sensitive and effective medical biomarkers for the diagnosis of neurological diseases. Therefore, to address this challenge, we propose a novel Deep Spatiotemporal Attention Network (DSTAN) framework for MCI recognition based on brain functional networks. Specifically, we first extract spatiotemporal features between brain functional signals and FBNs by designing a spatiotemporal convolution strategy (ST-CONV). Then, on this basis, we introduce a learned attention mechanism to further capture brain nodes strongly correlated with MCI. Finally, we fuse spatiotemporal features for MCI recognition. The entire network is trained in an end-to-end fashion. Extensive experiments show that our proposed method significantly outperforms current baselines and state-of-the-art methods, with a classification accuracy of 84.21%
Angiopoietin-2 impairs collateral artery growth associated with the suppression of the infiltration of macrophages in mouse hindlimb ischaemia
Abstract Background Angiopoietin-2 (Ang-2), a ligand of the Tie-2 receptor, plays an important role in maintaining endothelial cells and in destabilizing blood vessels. Collateral artery growth (arteriogenesis) is a key adaptive response to arterial occlusion. It is unknown whether the destabilization of blood vessels by Ang-2 can affect arteriogenesis and modulate mononuclear cell function. This study aimed to investigate the effects of Ang-2 on collateral artery growth. Methods Hindlimb ischaemia model was produced in C57BL/6 mice by femoral artery ligation. Blood flow perfusion was measured using a laser Doppler perfusion imager quantitative RT-PCR analysis was applied to identify the level of angiogenic factors. Results After the induction of hindlimb ischaemia, blood flow recovery was impaired in mice treated with recombinant Ang-2 protein; this was accompanied by a reduction of peri-collateral macrophage infiltration. In addition, quantitative RT-PCR analysis revealed that Ang-2 treatment decreased monocyte chemotactic protein-1 (MCP-1), platelet-derived growth factor-BB (PDGF-BB) mRNA levels in ischaemic adductor muscles. Ang-2 can lead to macrophage M1/M2 polarization shift inhibition in the ischaemic muscles. Furthermore, Ang-2 reduced the in vitro inflammatory response in macrophages and vascular cells involved in arteriogenesis. Conclusions Our results demonstrate that Ang-2 is essential for efficient arteriogenesis, which controls macrophage infiltration
In-Orbit Instrument Performance Study and Calibration for POLAR Polarization Measurements
POLAR is a compact space-borne detector designed to perform reliable
measurements of the polarization for transient sources like Gamma-Ray Bursts in
the energy range 50-500keV. The instrument works based on the Compton
Scattering principle with the plastic scintillators as the main detection
material along with the multi-anode photomultiplier tube. POLAR has been
launched successfully onboard the Chinese space laboratory TG-2 on 15th
September, 2016. In order to reliably reconstruct the polarization information
a highly detailed understanding of the instrument is required for both data
analysis and Monte Carlo studies. For this purpose a full study of the in-orbit
performance was performed in order to obtain the instrument calibration
parameters such as noise, pedestal, gain nonlinearity of the electronics,
threshold, crosstalk and gain, as well as the effect of temperature on the
above parameters. Furthermore the relationship between gain and high voltage of
the multi-anode photomultiplier tube has been studied and the errors on all
measurement values are presented. Finally the typical systematic error on
polarization measurements of Gamma-Ray Bursts due to the measurement error of
the calibration parameters are estimated using Monte Carlo simulations.Comment: 43 pages, 30 figures, 1 table; Preprint accepted by NIM
3D-Epigenomic Regulation of Gene Transcription in Hepatocellular Carcinoma.
The fundamental cause of transcription dysregulation in hepatocellular carcinoma (HCC) remains elusive. To investigate the underlying mechanisms, comprehensive 3D-epigenomic analyses are performed in cellular models of THLE2 (a normal hepatocytes cell line) and HepG2 (a hepatocellular carcinoma cell line) using integrative approaches for chromatin topology, genomic and epigenomic variation, and transcriptional output. Comparing the 3D-epigenomes in THLE2 and HepG2 reveal that most HCC-associated genes are organized in complex chromatin interactions mediated by RNA polymerase II (RNAPII). Incorporation of genome-wide association studies (GWAS) data enables the identification of non-coding genetic variants that are enriched in distal enhancers connecting to the promoters of HCC-associated genes via long-range chromatin interactions, highlighting their functional roles. Interestingly, CTCF binding and looping proximal to HCC-associated genes appear to form chromatin architectures that overarch RNAPII-mediated chromatin interactions. It is further demonstrated that epigenetic variants by DNA hypomethylation at a subset of CTCF motifs proximal to HCC-associated genes can modify chromatin topological configuration, which in turn alter RNAPII-mediated chromatin interactions and lead to dysregulation of transcription. Together, the 3D-epigenomic analyses provide novel insights of multifaceted interplays involving genetics, epigenetics, and chromatin topology in HCC cells
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