Quantifying the power of multiple event interpretations

A number of methods have been proposed recently which exploit multiple highly-correlated interpretations of events, or of jets within an event. For example, Qjets reclusters a jet multiple times and telescoping jets uses multiple cone sizes. Previous work has employed these methods in pseudo-experimental analyses and found that, with a simplified statistical treatment, they give sizable improvements over traditional methods. In this paper, the improvement gain from multiple event interpretations is explored with methods much closer to those used in real experiments. To this end, we derive a generalized extended maximum likelihood procedure. We study the significance improvement in Higgs to bb with both this method and the simplified method from previous analysis. With either method, we find that using multiple jet radii can provide substantial benefit over a single radius. Another concern we address is that multiple event interpretations might be exploiting similar information to that already present in the standard kinematic variables. By examining correlations between kinematic variables commonly used in LHC analyses and invariant masses obtained with multiple jet reconstructions, we find that using multiple radii is still helpful even on top of standard kinematic variables when combined with boosted decision trees. These results suggest that including multiple event interpretations in a realistic search for Higgs to bb would give additional sensitivity over traditional approaches.Comment: 13 pages, 2 figure

One-Dimensional Photonic Crystal Superprisms

Theoretical calculations indicate that it should be possible for one-dimensional (1D) photonic crystals (see figure) to exhibit giant dispersions known as the superprism effect. Previously, three-dimensional (3D) photonic crystal superprisms have demonstrated strong wavelength dispersion - about 500 times that of conventional prisms and diffraction gratings. Unlike diffraction gratings, superprisms do not exhibit zero-order transmission or higher-order diffraction, thereby eliminating cross-talk problems. However, the fabrication of these 3D photonic crystals requires complex electron-beam substrate patterning and multilayer thin-film sputtering processes. The proposed 1D superprism is much simpler in structural complexity and, therefore, easier to design and fabricate. Like their 3D counterparts, the 1D superprisms can exhibit giant dispersions over small spectral bands that can be tailored by judicious structure design and tuned by varying incident beam direction. Potential applications include miniature gas-sensing devices

Design and capacity performance analysis of wireless mesh network

Proceedings of: 5th International Conference on Mobile Technology, Applications, and Systems (Mobility 2008), (September 10-12, 2008), Yilan (Taiwan)From the network operator’s point of view, the high CAPEX/OPEX cost resulting from fixed/wired backhaul links can be inhibitive to successful deployment of broadband wireless services. The emerging wireless mesh network (WMN) technology is seen as one of the potential solutions which may reduce wired backhaul dependency through multihop transmission. Despite the advantages, many remain sceptical on WMN’s network capacity and scalability performances particularly when the user density is high. This paper provides an insight on the best possible upper-bound capacity performance of WMN, taking into consideration three key design parameters namely 1) Percentage of wired backhaul points per network, 2) Mesh-to-Access Link-Rate Ratio (R) and 3) Number of radio interfaces per mesh node including hybrid radio options. These design options are compared and contrasted with different deployment densities. The results generally show that the higher the number of backhaul points, the higher the effective access capacity available to mesh node and hence user domain. Increasing the R and the number of radio per mesh node are two alternative means to push up the effective access capacity per mesh node without increasing the number of wired backhaul points. This is most significant in multi radio system where about 80% of the backhaul points can be eliminated with R= 3 in order to maintain effective access capacity close to full rate (Capacity, C=1) per mesh node. It is also found that 50% of the backhaul points can be eliminated with R=2 for all radio options (except for the pure single radio case).European Community's Seventh Framework ProgramThis work was partially funded by the European Commission within the 7th Framework Program in the context of the ICT project CARMEN (Grant Agreement No. 214994) http://www.ict-carmen.eu

Resonant Tunneling Spin Pump

The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling

The Role of Gut Microbiota Urease in the Host With Liver Disease

Significant metabolic interactions exist between the gut microbiota and the mammalian host, one prime example of which is nitrogen metabolism. In the colon, bacterial urease hydrolyzes host-derived urea into carbon dioxide and ammonia. Colonic ammonia can subsequently be absorbed by the host or utilized by the gut microbiota for additional nitrogen metabolism. In patients with liver disease such as cirrhosis and congenital urea cycle disorders, hepatic abnormalities prevent the normal processing of ammonia, leading to hyperammonemia and hepatic encephalopathy (HE). Although circulating ammonia levels are correlated with damage to the central nervous system, the pathogenesis of HE is complex and not fully elucidated, hindering progress in treatment. Current treatment options including antibiotics, lactulose, and a low protein diet (LPD) are complicated by issues such as side effects, concerns of safety and efficacy in long-term use, and poor adherence. Our goal is to develop a safe, durable, and efficacious treatment for HE through the inoculation of a urease-free bacterial consortium. We show that we are able to engineer the gut microbiota to reduce fecal urease activity and ammonia levels in mice. Depletion of the endogenous gut microbiota followed by transplantation with Altered Schaedler Flora (ASF), a defined consortium of eight murine gut commensal bacteria with minimal urease gene content, established a persistent new community that exhibited long-term reduction in fecal urease activity and fecal ammonia production. ASF transplantation was associated with a decrease in morbidity and mortality in the thioacetamide (TAA) murine model of hepatic injury and fibrosis. Although the ASF consortium demonstrated reduced resilience in response to dietary stress, ASF transplantation led to further reductions in fecal ammonia on a LPD without exacerbating host metabolic dysfunction. These findings point to the potential use of a human urease-free bacterial consortium to alter clinical management and outcome in HE. Furthermore, they provide proof of concept that microbiota transplantation with a defined microbial consortium can lead to durable metabolic changes with therapeutic utility

Effects of zigzag edge states on the thermoelectric properties of finite-size armchair graphene nanoribbons

Thermoelectric properties of finite-size armchair graphene nanoribbons (AGNRs) coupled to metallic electrodes are theoretically studied in the framework of tight-binding model and Green's function approach. When the zigzag sides of AGNRs are coupled to the electrodes, the electron transport through the localized edge states can occur only if the channel length between electrodes is smaller than the decay length of these localized zigzag edge states. When the armchair edges are coupled to the electrodes, there is an interesting thermoelectric behavior associated with the mid-gap states when the AGNR is in the semiconducting phase. Here we show that the thermoelectric behavior of zigzag edge states of AGNRs with armchair sides connected to electrodes is similar to that of two parallel quantum dots with similar orbital degeneracy. Furthermore, it is demonstrated that the electrical conductance and power factor given by the zigzag edge states are quite robust against the defect scattering.Comment: 8 pages and 11 Figure