Potential energy landscape of monolayer-surface systems governed by repulsive lateral interactions: the case of (3 x 3)-I-Pt(111)

Combined density functional theory (DFT) and Monte Carlo (MC) approach is applied to study the potential energy landscape of four iodine atoms adsorbed on the Pt(111) surface in a (3 x 3) unit cell. Three critical points were identified: (3 x 3)-sym and (3 x 3)-asym, corresponding to structures well known from experimental studies, while the third one (3 x 3)-zigzag is a new structure not reported before. An interaction model fitted to DFT calculations allows us to explain the difference between arrangements of iodine monolayer in vacuum, air, and solution environments as a result of different repulsion regimes.     

Search for the standard model Higgs boson in the diphoton decay channel with 4.9 fb(-1) of pp collision data at √s=7 TeV with ATLAS

A search for the standard model Higgs boson is performed in the diphoton decay channel. The data used correspond to an integrated luminosity of 4.9 fb(-1) collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of √s=7 TeV. In the diphoton mass range 110-150 GeV, the largest excess with respect to the background-only hypothesis is observed at 126.5 GeV, with a local significance of 2.8 standard deviations. Taking the look-elsewhere effect into account in the range 110-150 GeV, this significance becomes 1.5 standard deviations. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges of 113-115 GeV and 134.5-136 GeV.     

Search for scalar bottom quark pair production with the ATLAS detector in pp collisions at sqrt[s]=7 TeV

The results of a search for pair production of the scalar partners of bottom quarks in 2.05 fb(-1) of pp collisions at sqrt[s]=7 TeV using the ATLAS experiment are reported. Scalar bottom quarks are searched for in events with large missing transverse momentum and two jets in the final state, where both jets are identified as originating from a bottom quark. In an R-parity conserving minimal supersymmetric scenario, assuming that the scalar bottom quark decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits are obtained in the b(1) - χ(1)(0) mass plane such that for neutralino masses below 60 GeV scalar bottom masses up to 390 GeV are excluded.     

Constrained random walks and vortex filaments in turbulence theory

We consider a simplified model of vorticity configurations in the inertial range of turbulent flow, in which vortex filaments are viewed as random walks in thermal equilibrium subjected to the constraints of helicity and energy conservation. The model is simple enough so that its properties can be investigated by a relatively straightforward Monte-Carlo method: a pivot algorithm with Metropolis weighting. Reasonable values are obtained for the intermittency dimensionD, a Kolmogorov-like exponent , and higher moments of the velocity derivatives. Qualitative conclusions are drawn regarding the origin of non-gaussian velocity statistics and regarding analogies with polymers and with systems near a critical point.This work was supported in part by the Applied Mathematical Sciences Subprogram of the Office of Energy Research, US Department of Energy, under Contract Number DE-AC03-76SF000098     

Search for a standard model Higgs boson in the H→ZZ→ℓ(+)ℓ(-)νν decay channel with the ATLAS detector

A search for a heavy standard model Higgs boson decaying via H→ZZ→→?(+)?(-)νν, where ?=e, μ, is presented. It is based on proton-proton collision data at √s=7 TeV, collected by the ATLAS experiment at the LHC in the first half of 2011 and corresponding to an integrated luminosity of 1.04 fb(-1). The data are compared to the expected standard model backgrounds. The data and the background expectations are found to be in agreement and upper limits are placed on the Higgs boson production cross section over the entire mass window considered; in particular, the production of a standard model Higgs boson is excluded in the region 340相似文献   

Enhanced quantum well infrared photodetector focal plane arrays for space applications

A 30 months European Space Agency project started in March 2008, whose overall purpose is to expand and assess the performance of broadband (11–15 μm) quantum detectors for spectro-imaging applications: Dispersive Spectrometers and Fourier Transform Spectrometers. We present here the technical requirements, the development approach chosen as well as preliminary experimental results. Our approach is fully compatible with the final array format (1024 × 256, pitch 50–60 μm). We expect the requested uniformity, operability and SNR levels to be achieved at temperatures close to the goal values. The performance level will be demonstrated on 256 × 256, 50 μm pitch arrays. Also, operability and uniformity issues will be addressed on large mechanical 1024 × 256 hybrid arrays.     

Errata: “Universality in Orthogonal and Symplectic Invariant Matrix Models with Quartic Potential”

The errata concern mainly the last computations for the universality of the local statistics of eigenvalues at the edge of the spectrum in parts (iii) of Theorems 2.3 and 2.4.     

Periodical cicadas: A minimal automaton model

The Magicicada spp. life cycles with its prime periods and highly synchronized emergence have defied reasonable scientific explanation since its discovery. During the last decade several models and explanations for this phenomenon appeared in the literature along with a great deal of discussion. Despite this considerable effort, there is no final conclusion about this long standing biological problem. Here, we construct a minimal automaton model without predation/parasitism which reproduces some of these aspects. Our results point towards competition between different strains with limited dispersal threshold as the main factor leading to the emergence of prime numbered life cycles.     

Use of very long-distance NOEs in a fully deuterated protein: an approach for rapid protein fold determination

The high sensitivity of modern NMR instrumentation, in combination with full deuteration, enabled the measurement of long-range NOEs between amide protons in a fully deuterated protein corresponding to distances up to 8A. These are beyond the limit normally observed in protonated samples. Such long-distance NOEs could be observed using long mixing times, which became possible due to reduced spin diffusion and T1 relaxation of the amide protons in the fully deuterated sample. This information was used in combination with secondary structure restraints derived from secondary chemical shifts for structure calculations. With these backbone amide proton NOEs only, a unique fold could be obtained with positional root mean square deviations from the average of 1.30 and 2.25 A for backbone and heavy atoms, respectively. Despite the low density of restraints, no mirror image problems were observed. Addition of sidechain NOE information increased the precision of the ensemble and in particular of the core packing. The structures obtained in this way were close to the published crystal structure. NOE completeness analysis revealed that the cumulative completeness is still more than 80% for an 8.0 A cut-off distance.     

A theoretical analysis of a piezoelectric ultrasound device with an active matching layer

This paper investigates the use of magnetically active materials in the matching layer of a piezoelectric transducer. This then allows the performance of the device to be dynamically altered by applying an external field. The effect that this new matching layer has on the performance of a typical device is theoretically investigated here. It transpires that the additional flexibility of an active matching layer can be used to maintain the efficiency of the device as the external load is varied.