On a coherent investigation of the spectrum of cosmic rays in the energy range of 10¹⁴ - 10¹⁸eV with KASCADE and KASCADE-Grande

The KASCADE experiment and its extension KASCADE-Grande have significantly contributed to the current knowledge about the energy spectrum and composition of cosmic rays (CRs) with energies between the knee and the ankle. However, the data of both experiments were analysed separately, although Grande used the muon information of the KASCADE-array. A coherent analysis based on the combined data of both arrays is expected to profit from reconstructed shower observables with even higher accuracy compared to the stand-alone analyses. In addition, a significantly larger fiducial area is available. The aim of this analysis is to obtain the spectrum and composition of CRs in the range from 10$^{14}$ to 10$^{18}$ eV with a larger number of events and further reduced uncertainties using one unique reconstruction procedure for the entire energy range. This contribution will describe the motivation, the concept, and the current status of the combined analysis

A cyclopentadienyl functionalized silylene-a flexible ligand for Si- And C-coordination

The synthesis of a 1,2,3,4-tetramethylcyclopentadienyl (Cp$^{4}$) substituted four-membered N-heterocyclic silylene [{PhC(NtBu) $_{2}$}Si(C$_{5}$Me$_{4}$H)] is reported first. Then, selected reactions with transition metal and a calcium precursor are shown. The proton of the Cp$_{4}$-unit is labile. This results in two different reaction pathways: (1) deprotonation and (2) rearrangement reactions. Deprotonation was achieved by the reaction of [{PhC(NtBu) $_{2}$}Si(C$_{5}$Me$_{4}$H)] with suitable zinc precursors. Rearrangement to [{PhC(NtBu) $_{2}$}(C$_{5}$Me$_{4}$)SiH], featuring a formally tetravalent silicon R$_{2}$CSi(R′)-H unit, was observed when the proton of the Cp$^{4}$ ring was shifted from the Cp$^{4}$-ring to the silylene in the presence of a Lewis acid. This allows for the coordination of the Cp$^{4}$-ring to a calcium compound. Furthermore, upon reaction with transition metal dimers [MCl(cod)] $_{2}$ (M = Rh, Ir; cod = 1,5-cyclooctadiene) the proton stays at the Cp$^{4}$-ring and the silylene reacts as a sigma donor, which breaks the dimeric structure of the precursors

2008-2009 President\u27s Report

The Linfield College President\u27s Annual Report is a collection of information about the year in review, including academics, student life and athletics, enrollment, finances, philanthropy, and leadership

Where do students in the health professions want to work?

<p>Abstract</p> <p>Background</p> <p>Rural and remote areas of Australia are facing serious health workforce shortages. While a number of schemes have been developed to improve recruitment to and retention of the rural health workforce, they will be effective only if appropriately targeted. This study examines the factors that most encourage students attending rural clinical placements to work in rural Australia, and the regions they prefer.</p> <p>Methods</p> <p>The Careers in Rural Health Tracking Survey was used to examine the factors that most influence medical, nursing and allied health students' preference for practice locations and the locations preferred.</p> <p>Results</p> <p>Students showed a preference for working in large urban centres within one year, but would consider moving to a more rural location later in life. Only 10% of students surveyed said they would never work in a rural community with a population of less than 10 000. Almost half the sample (45%) reported wanting to work overseas within five years. The type of work available in rural areas was found to be the factor most likely to encourage students to practice rurally, followed by career opportunities and challenge</p> <p>Conclusion</p> <p>The decision to practise rurally is the result of a complex interaction between a number of factors including ethnicity, discipline, age and sex, among others. Incentives that aim to entice all students to rural practice while considering only one of these variables are likely to be inadequate.</p

KASCADE-Grande Limits on the Isotropic Diffuse Gamma-Ray Flux between 100 TeV and 1 EeV

KASCADE and KASCADE-Grande were multi-detector installations to measure individual air showers of cosmic rays at ultra-high energy. Based on data sets measured by KASCADE and KASCADE-Grande, 90% C.L. upper limits to the flux of gamma-rays in the primary cosmic ray flux are determined in an energy range of ${10}^{14} - {10}^{18}$ eV. The analysis is performed by selecting air showers with a low muon content as expected for gamma-ray-induced showers compared to air showers induced by energetic nuclei. The best upper limit of the fraction of gamma-rays to the total cosmic ray flux is obtained at $3.7 \times {10}^{15}$ eV with $1.1 \times {10}^{-5}$. Translated to an absolute gamma-ray flux this sets constraints on some fundamental astrophysical models, such as the distance of sources for at least one of the IceCube neutrino excess models.Comment: Published in The Astrophysical Journal, Volume 848, Number 1. Posted on: October 5, 201

First Experimental Characterization of Microwave Emission from Cosmic Ray Air Showers

We report the first direct measurement of the overall characteristics of microwave radio emission from extensive air showers. Using a trigger provided by the KASCADE-Grande air shower array, the signals of the microwave antennas of the CROME (Cosmic-Ray Observation via Microwave Emission) experiment have been read out and searched for signatures of radio emission by high-energy air showers in the GHz frequency range. Microwave signals have been detected for more than 30 showers with energies above 3*10^16 eV. The observations presented in this Letter are consistent with a mainly forward-directed and polarised emission process in the GHz frequency range. The measurements show that microwave radiation offers a new means of studying air showers at energies above 10^17 eV.Comment: Accepted for publication in PR