2,813 research outputs found

    Selection rules for structured light in nanooligomers and other nanosystems

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    Structured light is a custom light field where the phase, polarization, and intensity vary with position. It has been used for nanotweezers, nanoscale imaging, and quantum information technology, but its role in exciting optical transitions in materials has been little examined so far. Here we use group theory to derive the optical selection rules for nanosystems that get excited by structured light. If the size of the nanostructure is comparable to the light wavelength, it will sample the full beam profile during excitation with profound consequences on optical excitations. Using nano-oligomers as model nanosystems, we show that structured light excites optical transitions that are forbidden for linearly polarized or unpolarized light. Such dipole forbidden modes have longer lifetimes and narrower resonances than dipole-allowed transitions. We derive symmetry-adapted eigenmodes for nano-oligomers containing up to six monomers. Our study includes tables with selection rules for cylindrical vector beams, for beams with orbital angular momentum, and for field retardation along the propagation direction. We discuss multiphoton processes of nonlinear optics in addition to one-photon absorption. Structured light will unlock a broad range of excitations in nano-oligomers and other nanostructures that are currently inaccessible to optical studies

    Radiation hardness of diamond and silicon sensors compared

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    The radiation hardness of silicon charged particle sensors is compared with single crystal and polycrystalline diamond sensors, both experimentally and theoretically. It is shown that for Si- and C-sensors, the NIEL hypothesis, which states that the signal loss is proportional to the Non-Ionizing Energy Loss, is a good approximation to the present data. At incident proton and neutron energies well above 0.1 GeV the radiation damage is dominated by the inelastic cross section, while at non-relativistic energies the elastic cross section prevails. The smaller inelastic nucleon-Carbon cross section and the light nuclear fragments imply that at high energies diamond is an order of magnitude more radiation hard than silicon, while at energies below 0.1 GeV the difference becomes significantly smaller.Comment: 6 pages, 4 figurs, invited talk at the Hasselt Diamond Workshop, Feb. 200

    Familial colorectal cancer: eleven years of data from a registry program in Switzerland

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    Deleterious germ-line variants involving the DNA mismatch repair (MMR) genes have been identified as the cause of the hereditary nonpolyposis colorectal cancer syndrome known as the Lynch syndrome, but in numerous familial clusters of colon cancer, the cause remains obscure. We analyzed data for 235 German-speaking Swiss families with nonpolyposis forms of colorectal cancer (one of the largest and most ethnically homogeneous cohorts of its kind) to identify the phenotypic features of forms that cannot be explained by MMR deficiency. Based on the results of microsatellite instability analysis and immunostaining of proband tumor samples, the kindreds were classified as MMR-proficient (n=134, 57%) or MMR-deficient (n=101, 43%). In 81 of the latter kindreds, deleterious germ-line MMR-gene variants have already been found (62 different variants, including 13 that have not been previously reported), confirming the diagnosis of Lynch syndrome. Compared with MMR-deficient kindreds, the 134 who were MMR proficient were less likely to meet the Amsterdam Criteria II regarding autosomal dominant transmission. They also had primary cancers with later onset and colon-segment distribution patterns resembling those of sporadic colorectal cancers, and they had lower frequencies of metachronous colorectal cancers and extracolonic cancers in general. Although the predisposition to colorectal cancer in these kindreds is probably etiologically heterogeneous, we were unable to identify distinct phenotypic subgroups solely on the basis of the clinical data collected in this study. Further insight, however, is expected to emerge from the molecular characterization of their tumor

    New insights into lake responses to rapid climate change : the Younger Dryas in Lake Goscia(z) over dot, central Poland

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    The sediment profile from Lake Goscia(z) over dot in central Poland comprises a continuous, seasonally resolved and exceptionally well-preserved archive of the Younger Dryas (YD) climate variation. This provides a unique opportunity for detailed investigation of lake system responses during periods of rapid climate cooling (YD onset) and warming (YD termination). The new varve record of Lake Goscia(z) over dot presented here spans 1662 years from the late Allerod (AL) to the early Preboreal (PB). Microscopic varve counting provides an independent chronology with a YD duration of 1149+14/-22 years, which confirms previous results of 1140 +/- 40 years. We link stable oxygen isotopes and chironomid-based air temperature reconstructions with the response of various geochemical and varve microfacies proxies especially focusing on the onset and termination of the YD. Cooling at the YD onset lasted similar to 180 years, which is about a century longer than the terminal warming that was completed in similar to 70 years. During the AL/YD transition, environmental proxy data lagged the onset of cooling by similar to 90 years and revealed an increase of lake productivity and internal lake re-suspension as well as slightly higher detrital sediment input. In contrast, rapid warming and environmental changes during the YD/PB transition occurred simultaneously. However, initial changes such as declining diatom deposition and detrital input occurred already a few centuries before the rapid warming at the YD/PB transition. These environmental changes likely reflect a gradual increase in summer air temperatures already during the YD. Our data indicate complex and differing environmental responses to the major climate changes related to the YD, which involve different proxy sensitivities and threshold processes.Peer reviewe

    Evaluation of Clinical Risk Factors to Predict High On-Treatment Platelet Reactivity and Outcome in Patients with Stable Coronary Artery Disease (PREDICT-STABLE)

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    Objectives This study was designed to identify the multivariate effect of clinical risk factors on high on-treatment platelet reactivity (HPR) and 12 months major adverse events (MACE) under treatment with aspirin and clopidogrel in patients undergoing non-urgent percutaneous coronary intervention (PCI). Methods 739 consecutive patients with stable coronary artery disease (CAD) undergoing PCI were recruited. On-treatment platelet aggregation was tested by light transmittance aggregometry. Clinical risk factors and MACE during one-year follow-up were recorded. An independent population of 591 patients served as validation cohort. Results Degree of on-treatment platelet aggregation was influenced by different clinical risk factors. In multivariate regression analysis older age, diabetes mellitus, elevated BMI, renal function and left ventricular ejection fraction were independent predictors of HPR. After weighing these variables according to their estimates in multivariate regression model, we developed a score to predict HPR in stable CAD patients undergoing elective PCI (PREDICT-STABLE Score, ranging 0-9). Patients with a high score were significantly more likely to develop MACE within one year of follow-up, 3.4% (score 0-3), 6.3% (score 4-6) and 10.3% (score 7-9); odds ratio 3.23, P=0.02 for score 7-9 vs. 0-3. This association was confirmed in the validation cohort. Conclusions Variability of on-treatment platelet function and associated outcome is mainly influenced by clinical risk variables. Identification of high risk patients (e.g. with high PREDICT-STABLE score) might help to identify risk groups that benefit from more intensified antiplatelet regimen. Additional clinical risk factor assessment rather than isolated platelet function-guided approaches should be investigated in future to evaluate personalized antiplatelet therapy in stable CAD-patients

    Flavor structure of the octet magnetic moments

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    We use the chiral quark-soliton model to identify all symmetry breaking terms linear in msm_{s} and investigate the strange magnetic moment in a ``model-independent'' way. Assuming hedgehog symmetry and employing the collective quantization, we obtain the most general expression for the flavor-singlet and flavor-octet magnetic moments in terms of seven independent parameters. Having fitted these parameters to the experimental magnetic moments of the octet baryons, we show that the strange magnetic moment turns out to be positive. The best fit obtained by minimizing χ2\chi^2 assuming 15% theoretical accuracy yields: ÎŒN(s)=(0.41±0.18)ÎŒN\mu^{({\rm s})}_{N} = (0.41 \pm 0.18) \mu_{N}.Comment: 10 pages. RevTeX is used. One figure is included. The final version accepted for publication in Phys. Rev.

    New Biocomposites for Innovative Construction Facades and Interior Partitions

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    Osirys is a European Research Project where a holistic solution for façades and interior partitions ready to be applied in building retrofitting and new construction has been developed. The project uses biocomposites as the base material to define different products: a multilayer façade, a curtain wall, a window, and an interior partition. The biocomposites developed have different functionalities able to meet the strictest requisites of the European Building Codes in relation to fire and structural performance, improve indoor air quality through the elimination of VOCs (volatile organic compounds) and microorganisms, increase thermal insulation, and increase the durability of construction elements. The new systems are lighter than traditional ones, leading to reductions in overall weight, thereby reducing implementation costs during both manufacturing and assembly processes, thanks to an industrialised concept that utilises modular elements. The project was developed with the collaboration of 18 European partners (5 research centres, 9 SMEs, 2 large industries, and 2 public bodies). The main activities were devoted to the establishment of requirements, the development of materials, the design of products, the integration of materials into products, the verification of properties by simulation and testing according to EU standards, the integration of products into real buildings, and economic and environmental assessment. The scope of this paper is to provide a general overview of the entire project work and results to demonstrate the feasibility of using biocomposites in envelope solutions with the aim of solving some of the main problems that exist in façade traditional solutions. The project finishes with the implementation of the developments in real buildings as prototypes; further research is required before industrial scale manufacturing of the systems can be launched into the market.This work was supported by the EU under the 7th Framework programme of research, technological development, and demonstration project titled: “Forest based composites for façades and interior partitions to improve indoor air quality in new builds and restoration” under grant agreement nÂș 609067. The development of this article and of this project would not have been possible without the collaboration of all consortium partners: FundaciĂłn Tecnalia, Acciona Infraestructuras, Teknologian Tutkimuskeskus VTT, Fraunhofer-Gesellschaft zur Foerderung der Angewandten Forschung EV, Research Association of Plastic and Related Materials (AIMPLAS), IVL Svenska Miljoeinstitutet AB, Tartu Stad, Tecnaro Gesellschaft zur Industriellen Anwendung Nachwachsender Rohstoffe MBH, Netcomposites Limited, Omikron-Dokk Muanyagiparo kft, Conenor Oy, Van Berkel & Bos UN STUDIO B.V., Amorim Cork Composites SA, ENAR Envolventes arquitectĂłnicas, Bergamo Tecnologie Spzoo, VISESA, SICC GMBH and Collanti Concorde SRL

    A Thin Skin Calorimeter (TSC) for Quantifying Irradiation During Large-scale Fire Testing

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    This paper details a novel method for quantifying irradiation (incident radiant heat flux) at the exposed surface of solid elements during large-scale fire testing. Within the scope of the work presented herein, a type of Thin Skin Calorimeter (TSC) was developed intending for a practical, low cost device enabling the cost-effective mass production required for characterising the thermal boundary conditions during multiple large-scale fire tests. The technical description of the TSC design and a formulation of the proposed calibration technique are presented. This methodology allows for the quantification of irradiation by means of an a posteriori analysis based on a temperature measurement from the TSC, a temperature measurement of the gas-phase in the vicinity of the TSC and a correction factor defined during a pre-test calibration process. The proposed calibration methodology is designed to account for uncertainties inherent to the simplicity of the irradiation measurement technique, therefore not requiring precise information regarding material thermal and optical properties. This methodology is designed and presented so as to enable adaption of the technique to meet the specific requirements of other experimental setups. This is conveyed by means of an example detailing the design and calibration of a device designed for a series of large-scale experiments as part of the ‘Real Fires for the Safe Design of Tall Buildings’ project

    Search for R-parity-violating supersymmetry in events with four or more leptons in sqrt(s) =7 TeV pp collisions with the ATLAS detector

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    A search for new phenomena in final states with four or more leptons (electrons or muons) is presented. The analysis is based on 4.7 fb−1 of s=7  TeV \sqrt{s}=7\;\mathrm{TeV} proton-proton collisions delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in two signal regions: one that requires moderate values of missing transverse momentum and another that requires large effective mass. The results are interpreted in a simplified model of R-parity-violating supersymmetry in which a 95% CL exclusion region is set for charged wino masses up to 540 GeV. In an R-parity-violating MSUGRA/CMSSM model, values of m 1/2 up to 820 GeV are excluded for 10 < tan ÎČ < 40

    Search for high-mass resonances decaying to dilepton final states in pp collisions at s√=7 TeV with the ATLAS detector

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    The ATLAS detector at the Large Hadron Collider is used to search for high-mass resonances decaying to an electron-positron pair or a muon-antimuon pair. The search is sensitive to heavy neutral Zâ€Č gauge bosons, Randall-Sundrum gravitons, Z * bosons, techni-mesons, Kaluza-Klein Z/Îł bosons, and bosons predicted by Torsion models. Results are presented based on an analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.9 fb−1 in the e + e − channel and 5.0 fb−1 in the ÎŒ + ÎŒ −channel. A Z â€Č boson with Standard Model-like couplings is excluded at 95 % confidence level for masses below 2.22 TeV. A Randall-Sundrum graviton with coupling k/MPl=0.1 is excluded at 95 % confidence level for masses below 2.16 TeV. Limits on the other models are also presented, including Technicolor and Minimal Zâ€Č Models
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