439 research outputs found

    Colloidal Nanocrystals by Design

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    Density Functional Theory investigations have recently emerged as a most valuable tool to understand in atomistic details how tuning and modulating the ionic composition of semiconductor materials affect the emission and absorbance of the corresponding colloidal nanocrystals, ultimately providing guidance for the selection of suitable precursors in their syntheses. In this view, the third year of my doctorate studies focused on acquiring and reinforcing a detailed knowledge of the structural and electronic properties of two emerging classes of semiconductor materials in the nanocrystals field - double perovskites and «low-dimensional» metal halides

    Lead-Free Halide Perovskite Materials and Optoelectronic Devices: Progress and Prospective

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    Halide perovskites, in the form of thin films and colloidal nanocrystals, have recently taken semiconductor optoelectronics research by storm, and have emerged as promising candidates for high-performance solar cells, light-emitting diodes (LEDs), lasers, photodetectors, and radiation detectors. The impressive optical and optoelectronic properties, along with the rapid increase in efficiencies of solar cells and LEDs, have greatly attracted researchers across many disciplines. However, most advances made so far in terms of preparation (colloidal nanocrystals and thin films), and the devices with highest efficiencies are based on Pb-based halide perovskites, which have raised concerns over their commercialization due to the toxicity of Pb. This has triggered the search for lower-toxicity Pb-free halide perovskites and has led to significant progress in the last few years. In this roadmap review, researchers of different expertise have joined together to summarize the latest progress, outstanding challenges, and future directions of Pb-free halide perovskite thin films and nanocrystals, regarding their synthesis, optical spectroscopy, and optoelectronic devices, to guide the researchers currently working in this area as well as those that will join the field in the future.I.L.-F., D.V., C.-Y.W., S.S., T.O., Y.-T.H., K.S., Y.L., V.S.C., J.Z., L.D.T., and D.G. contributed equally to this work. L.P. acknowledges the support from the Spanish Ministerio de Ciencia e Innovación through the Ramón y Cajal grant (RYC2018-026103-I) and the Spanish State Research Agency (Grant No. PID2020-117371RA-I00; TED2021-131628A-100), as well as the grant from the Xunta de Galicia (ED431F2021/05). C.-Y.W. acknowledges the financial support from Alexander von Humboldt Foundation. K.S. acknowledges the financial support from China Scholarship Council (CSC), and P.M.-B. acknowledges support from Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy – EXC 2089/1–390776260 (e-conversion). V.B. and T.O. acknowledge the MEXT JSPS Grants 20J00974, 21K14580, and 23H01781. H.Z acknowledges the financial supported by NSFC (62222405, 52131304), the Natural Science Foundation of Jiangsu Province (BK20220142), the Fundamental Research Funds for the Central Universities (30922010713), and NSFC-RGC (62261160392). H.-T.S. acknowledges the financial support from JSPS KAKENHI (21H01743). Y.-T.H and R.L.Z.H. would like to thank the Engineering and Physical Sciences Research Council (EPSRC) for funding (no. EP/V014498/2). R.L.Z.H. also thanks the Royal Academy of Engineering through the Research Fellowships scheme (no. RF∖201718∖17101). D.V. and E.D. acknowledge financial support from the Research Foundation – Flanders through an FWO doctoral fellowship to D.V. (FWO Grant Number 1S45223N) and the KU Leuven Internal Funds (Grant Numbers STG/21/010, C14/23/090, and CELSA/23/018). T.D. acknowledges the Department of Science and Technology (DST) and the Science and Engineering Research Board (SERB) for the Ramanujan Fellowship Award (RJF/2021/000125). I.M.-S. acknowledges Ministry of Science and Innovation of Spain under Step-Up (TED2021-131600B-C31) project and by Generalitat Valenciana under Print-P (MFA/2022/020) project. V.S.C., I.M.-S. and J.P.M.-P acknowledges the support of the Horizon 2020 research and innovation program through the DROP-IT project (grant agreement no. 862656)

    Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

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    One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI

    Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

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    This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

    Search for stop and higgsino production using diphoton Higgs boson decays

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    Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top-quark (stop) and the Higgs boson (higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 inverse femtobarns of proton-proton collision data at sqrt(s) = 8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the stop mass below 360 to 410 GeV, depending on the higgsino mass

    Severe early onset preeclampsia: short and long term clinical, psychosocial and biochemical aspects

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    Preeclampsia is a pregnancy specific disorder commonly defined as de novo hypertension and proteinuria after 20 weeks gestational age. It occurs in approximately 3-5% of pregnancies and it is still a major cause of both foetal and maternal morbidity and mortality worldwide1. As extensive research has not yet elucidated the aetiology of preeclampsia, there are no rational preventive or therapeutic interventions available. The only rational treatment is delivery, which benefits the mother but is not in the interest of the foetus, if remote from term. Early onset preeclampsia (<32 weeks’ gestational age) occurs in less than 1% of pregnancies. It is, however often associated with maternal morbidity as the risk of progression to severe maternal disease is inversely related with gestational age at onset2. Resulting prematurity is therefore the main cause of neonatal mortality and morbidity in patients with severe preeclampsia3. Although the discussion is ongoing, perinatal survival is suggested to be increased in patients with preterm preeclampsia by expectant, non-interventional management. This temporising treatment option to lengthen pregnancy includes the use of antihypertensive medication to control hypertension, magnesium sulphate to prevent eclampsia and corticosteroids to enhance foetal lung maturity4. With optimal maternal haemodynamic status and reassuring foetal condition this results on average in an extension of 2 weeks. Prolongation of these pregnancies is a great challenge for clinicians to balance between potential maternal risks on one the eve hand and possible foetal benefits on the other. Clinical controversies regarding prolongation of preterm preeclamptic pregnancies still exist – also taking into account that preeclampsia is the leading cause of maternal mortality in the Netherlands5 - a debate which is even more pronounced in very preterm pregnancies with questionable foetal viability6-9. Do maternal risks of prolongation of these very early pregnancies outweigh the chances of neonatal survival? Counselling of women with very early onset preeclampsia not only comprises of knowledge of the outcome of those particular pregnancies, but also knowledge of outcomes of future pregnancies of these women is of major clinical importance. This thesis opens with a review of the literature on identifiable risk factors of preeclampsia

    Search for anomalous production of events with three or more leptons in pp collisions at √s = 8TeV

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    Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.A search for physics beyond the standard model in events with at least three leptons is presented. The data sample, corresponding to an integrated luminosity of 19.5fb-1 of proton-proton collisions with center-of-mass energy s=8TeV, was collected by the CMS experiment at the LHC during 2012. The data are divided into exclusive categories based on the number of leptons and their flavor, the presence or absence of an opposite-sign, same-flavor lepton pair (OSSF), the invariant mass of the OSSF pair, the presence or absence of a tagged bottom-quark jet, the number of identified hadronically decaying τ leptons, and the magnitude of the missing transverse energy and of the scalar sum of jet transverse momenta. The numbers of observed events are found to be consistent with the expected numbers from standard model processes, and limits are placed on new-physics scenarios that yield multilepton final states. In particular, scenarios that predict Higgs boson production in the context of supersymmetric decay chains are examined. We also place a 95% confidence level upper limit of 1.3% on the branching fraction for the decay of a top quark to a charm quark and a Higgs boson (t→cH), which translates to a bound on the left- and right-handed top-charm flavor-violating Higgs Yukawa couplings, λtcH and λctH, respectively, of |λtcH|2+|λctH|2<0.21

    Electroweak production of two jets in association with a Z boson in proton-proton collisions root s =13 TeV

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    A measurement of the electroweak (EW) production of two jets in association with a Z boson in proton-proton collisions at root s = 13 TeV is presented, based on data recorded in 2016 by the CMS experiment at the LHC corresponding to an integrated luminosity of 35.9 fb(-1). The measurement is performed in the lljj final state with l including electrons and muons, and the jets j corresponding to the quarks produced in the hard interaction. The measured cross section in a kinematic region defined by invariant masses m(ll) > 50 GeV, m(jj) > 120 GeV, and transverse momenta P-Tj > 25 GeV is sigma(EW) (lljj) = 534 +/- 20 (stat) fb (syst) fb, in agreement with leading-order standard model predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. No evidence is found and limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are -2.6 <cwww/Lambda(2) <2.6 TeV-2 and -8.4 <cw/Lambda(2) <10.1 TeV-2. The additional jet activity of events in a signal-enriched region is also studied, and the measurements are in agreement with predictions.Peer reviewe

    Measurement of associated W plus charm production in pp collisions at √s=7 TeV

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