The Leptoquark Implication from the CMS and IceCube Experiments

The recent excess in the CMS measurements of $eejj$ and $e\nu jj$ channels and the emergence of PeV comsic neutrino events at the IceCube experiment share an intriguing implication for a leptoquark with a 600-650 GeV mass. We investigate the CMS constraints on the flavor structure of a scenario with the minimal leptoquark Yukawa couplings and correlate such a scenario to the resonant enhancement in the very high energy shower event rates at the IceCube. We find for a single leptoquark, the CMS signals require large couplings to the third generation leptons. This leads to an enhancement in the $\nu_\tau$-nucleon scattering cross-section and subsequently more $\nu_\tau$ events at PeV energies. However, a visible enhancement above the Standard Model scattering would require a leptoquark Yukawa coupling larger than one that can be easily tested at the upcoming LHC runs.Comment: PRD version. Meson decay constraints and additional citations are added. 6 pages, 2 figures, 1 tabl

Hyper-velocity impact test and simulation of a double-wall shield concept for the Wide Field Monitor aboard LOFT

The space mission LOFT (Large Observatory For X-ray Timing) was selected in 2011 by ESA as one of the candidates for the M3 launch opportunity. LOFT is equipped with two instruments, the Large Area Detector (LAD) and the Wide Field Monitor (WFM), based on Silicon Drift Detectors (SDDs). In orbit, they would be exposed to hyper-velocity impacts by environmental dust particles, which might alter the surface properties of the SDDs. In order to assess the risk posed by these events, we performed simulations in ESABASE2 and laboratory tests. Tests on SDD prototypes aimed at verifying to what extent the structural damages produced by impacts affect the SDD functionality have been performed at the Van de Graaff dust accelerator at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg. For the WFM, where we expect a rate of risky impacts notably higher than for the LAD, we designed, simulated and successfully tested at the plasma accelerator at the Technical University in Munich (TUM) a double-wall shielding configuration based on thin foils of Kapton and Polypropylene. In this paper we summarize all the assessment, focussing on the experimental test campaign at TUM.Comment: Proc. SPIE 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 91446

Effects of impurity scattering on electron-phonon resonances in semiconductor superlattice high-field transport

A non-equilibrium Green's function method is applied to model high-field quantum transport and electron-phonon resonances in semiconductor superlattices. The field-dependent density of states for elastic (impurity) scattering is found non-perturbatively in an approach which can be applied to both high and low electric fields. I-V curves, and specifically electron-phonon resonances, are calculated by treating the inelastic (LO phonon) scattering perturbatively. Calculations show how strong impurity scattering suppresses the electron-phonon resonance peaks in I-V curves, and their detailed sensitivity to the size, strength and concentration of impurities.Comment: 7 figures, 1 tabl

Postulates for Revocation Schemes

In access control frameworks with the possibility of delegating permissions and administrative rights, delegation chains can form. There are di erent ways to treat these delegation chains when revoking rights, which give rise to di erent revocation schemes. Hagstr om et al. [11] proposed a framework for classifying revocation schemes, in which the di erent revocation schemes are de ned graph-theoretically. At the outset, we identify multiple problems with Hagstr om et al.'s de nitions of the revocation schemes, which can pose security risks. This paper is centered around the question how one can systematically ensure that improved de nitions of the revocation schemes do not lead to similar problems. For this we propose to apply the axiomatic method originating in social choice theory to revocation schemes. Our use of the axiomatic method resembles its use in belief revision theory. This means that we de ne postulates that describe the desirable behaviour of revocation schemes, study which existing revocation frameworks satisfy which postulates, and show how all de ned postulates can be satis ed by de ning the revocation schemes in a novel way

Light, stratification and zooplankton as controlling factors for the spring development of phytoplankton in Lake Constance

The patterns of phytoplankton growth and decline during the spring bloom and the following clear-water phase in Lake Constance have been studied on the basis of cell counts with short-term sampling intervals and related to light climate, stratification and zooplankton pressure

A new cell primo-culture method for freshwater benthic diatom communities

A new cell primo-culture method was developed for the benthic diatom community isolated from biofilm sampled in rivers. The approach comprised three steps: (1) scraping biofilm from river pebbles, (2) diatom isolation from biofilm, and (3) diatom community culture. With a view to designing a method able to stimulate the growth of diatoms, to limit the development of other microorganisms, and to maintain in culture a community similar to the original natural one, different factors were tested in step 3: cell culture medium (Chu No 10 vs Freshwater “WC” medium modified), cell culture vessel, and time of culture. The results showed that using Chu No 10 medium in an Erlenmeyer flask for cell culture was the optimal method, producing enough biomass for ecotoxicological tests as well as minimising development of other microorganisms. After 96 h of culture, communities differed from the original communities sampled in the two rivers studied. Species tolerant of eutrophic or saprobic conditions were favoured during culture. This method of diatom community culture affords the opportunity to assess, in vitro, the effects of different chemicals or effluents (water samples andindustrial effluents) on diatom communities, as well as on diatom cells, from a wide range of perspectives

An examination of the precipitation delivery mechanisms for Dolleman Island, eastern Antarctic Peninsula

Copyright @ 2004 Wiley-BlackwellThe variability of size and source of significant precipitation events were studied at an Antarctic ice core drilling site: Dolleman Island (DI), located on the eastern coast of the Antarctic Peninsula. Significant precipitation events that occur at DI were temporally located in the European Centre for Medium-Range Weather Forecasting (ECMWF) reanalysis data set, ERA-40. The annual and summer precipitation totals from ERA-40 at DI both show significant increases over the reanalysis period. Three-dimensional backwards air parcel trajectories were then run for 5 d using the ECMWF ERA-15 wind fields. Cluster analyses were performed on two sets of these backwards trajectories: all days in the range 1979–1992 (the climatological time-scale) and a subset of days when a significant precipitation event occurred. The principal air mass sources and delivery mechanisms were found to be the Weddell Sea via lee cyclogenesis, the South Atlantic when there was a weak circumpolar trough (CPT) and the South Pacific when the CPT was deep. The occurrence of precipitation bearing air masses arriving via a strong CPT was found to have a significant correlation with the southern annular mode (SAM); however, the arrival of air masses from the same region over the climatological time-scale showed no such correlation. Despite the dominance in both groups of back trajectories of the westerly circulation around Antarctica, some other key patterns were identified. Most notably there was a higher frequency of lee cyclogenesis events in the significant precipitation trajectories compared to the climatological time-scale. There was also a tendency for precipitation trajectories to come from more northerly latitudes, mostly from 50–70°S. The El Niño Southern Oscillation (ENSO) was found to have a strong influence on the mechanism by which the precipitation was delivered; the frequency of occurrence of precipitation from the east (west) of DI increased during El Niño (La Niña) events

Металографічний аналіз потенційних ділянок зародження руйнування зони термічного вливу низьковуглицевих сталей після лазерного зварювання

The work investigates the detection of dangerous areas of the zones of thermal impact on the basis of the research of welding joint structure formation after laser welding of low-carbon steels 09Mn2Si, 10CrNiCu, 10Mn2VNb. The complex of studies carried out showed that the welded joint is structurally divided into several zones. At the same time, metallographic analysis showed that in the zones of the welded joint there is a conglomerate of structures, which contains components characteristic both for metal in the cast state and for metal after accelerated cooling.Досліджено виявлення небезпечних ділянок зони термічного впливу на підставі дослідження формування структури зварного з'єднання після лазерного зварювання низьковуглецевих сталей 09Г2С, 10ХСНД, 10Г2ФБ. Проведений комплекс досліджень показав, що зварене з'єднання структурно розділити на кілька зон. При цьому, металографічний аналіз показав, що в зонах зварного з'єднання присутні конгломерат структур, який містить складові характерні як для металу в литому стані так і для металу після прискореного охолодження.Исследовано выявление опасных участков зоны термического влияния на основании исследования формирования структуры сварного соединения после лазерной сварки низкоуглеродистых сталей 09Г2С, 10ХСНД, 10Г2ФБ. Проведенный комплекс исследований показал, что сварное соединение структурно разделить на несколько зон. При этом, металлографический анализ показал, что в зонах сварного соединения присутствуют конгломерат структур, который содержит составляющие характерные как для металла в литом состоянии так и для металла после ускоренного охлаждения