3,107 research outputs found
Non-collinearity in di-jet fragmentation in electron-positron scattering
We study fragmentation in electron-positron annihilation assuming a di-jet
situation, using variables defined independent of any frame. In a collinear
situation some of the variables are centered around zero with the small
deviations attributed to intrinsic transverse momenta and large deviations
attributed to additional hard subprocesses. Of course there is a gradual
transition. Our modest goal is to show that covariantly defined variables are
well suited to get a feeling for the magnitude of intrinsic transverse momenta.Comment: 10 pages, 12 figures, several minor correction
The HERMES recoil photon detector and the study of deeply virtual Compton scattering
The study of deeply virtual Compton scattering (DVCS) gives information about the contribution of the quark orbital angular momentum to the spin of the proton. DVCS has been studied at the HERMES experiment at DESY in Hamburg. Here 27.6 GeV longitudinally polarized electrons and positrons were scattered off a gaseous proton target. For the analysis of DVCS the recoiling proton could not be detected, but was reconstructed via its missing mass. This method suffers, however, from a 14% background contribution, mainly originating from associated DVCS. In this process the proton does not stay in its ground state but is excited to a Delta+ resonance.
In order to reduce the background contribution down to less than 1%, a recoil detector was installed in the HERMES experiment beginning of 2006. This detector consists of three subcomponents, of which one is the photon detector. The main function of the photon detector is the detection of Delta+ decay photons.
The photon detector was started up and commissioned for the analysis of (associated) DVCS. Subsequently DVCS and associated DVCS were analyzed using the recoil detector
Reply to Comment on "Reevaluation of the parton distribution of strange quarks in the nucleon"
A Comment on the recently published reevaluation of the polarization-averaged
parton distribution of strange quarks in the nucleon using final data on the
multiplicities of charged kaons in semi-inclusive deep-inelastic scattering is
reviewed. Important features of the comparison of one-dimensional projections
of the multidimensional HERMES data are pointed out. A test of the
leading-order extraction of xS(x) using the difference between charged-kaon
multiplicities is repeated. The results are consistent with leading-order
predictions within the uncertainties in the input data, and do not invalidate
the earlier extraction of xS(x).Comment: Reply Comment to arXiv:1407.372
Measurements of Isospin Asymmetry and Difference of Direct CP Asymmetries in Inclusive B→Xsγ Decays
We report measurements of isospin asymmetry Delta(0-) and difference of direct CP asymmetries Delta A(CP) between charged and neutral B -> X-s gamma decays. This analysis is based on the data sample containing 772 x 10(6)B (B) over bar pairs that was collected with the Belle detector at the KEKB energy-asymmetric ethornecollider. Using a sum-of-exclusive technique with invariant X-s mass up to 2.8 GeV= c2, we obtain Delta(0-) = [0.48 +/- 1.49(stat) +/- 0.97(syst) +/- 1.15(f(+-)/f(00))]% and Delta A(CP) = [+3.69 +/- 2.65(stat) +/- 0.76(syst)]%, where the last uncertainty for.0-is due to the uncertainty on the production ratio of B+B- to B-0(B) over bar (0) in.o4Sthorn decays. The measured value of Delta(0-) is consistent with zero, allowing us to constrain the resolved photon contribution in the B -> X-s gamma, and improve the branching fraction prediction. The result for Delta A(CP) is consistent with the prediction of the SM. We also measure the direct CP asymmetries for charged and neutral B -> X-s gamma decays. All the measurements are the most precise to date.The authors would like to thank M. Misiak, G. Paz and M. Endo for fruitful discussions. A. I. is supported by the Japan Society for the Promotion of Science (JSPS) Grant No. 16H03968. We thank the KEKB group for the excellent operation of the accelerator; the KEK cryogenics group for the efficient operation of the solenoid; and the KEK computer group, the National Institute of Informatics, and the Pacific Northwest National Laboratory (PNNL) Environmental Molecular Sciences Laboratory (EMSL) computing group for valuable computing and Science Information NETwork 5 (SINET5) network support. We acknowledge support from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan, the Japan Society for the Promotion of Science (JSPS), and the Tau-Lepton Physics Research Center of Nagoya University; the Australian Research Council; Austrian Science Fund under Grant No. P 26794-N20; the National Natural Science Foundation of China under Contracts No. 11435013, No. 11475187, No. 11521505, No. 11575017, No. 11675166, No. 11705209; Key Research Programof Frontier Sciences, Chinese Academy of Sciences (CAS), Grant No. QYZDJ-SSW-SLH011; the CAS Center for Excellence in Particle Physics (CCEPP); Fudan University Grant No. JIH5913023, No. IDH5913011/003, No. JIH5913024, No. IDH5913011/002; the Ministry of Education, Youth and Sports of the Czech Republic under Contract No. LTT17020; the Carl Zeiss Foundation, the Deutsche Forschungsgemeinschaft, the Excellence Cluster Universe, and the VolkswagenStiftung; the Department of Science and Technology of India; the Istituto Nazionale di Fisica Nucleare of Italy; National Research Foundation (NRF) of Korea Grants No. 2014R1A2A2A01005286, No. 2015R1A2A2A01003280, No. 2015H1A2A1033649, No. 2016R1D1A1B01010135, No. 2016K1A3A7A09005 603, No. 2016R1D1A1B02012900; Radiation Science Research Institute, Foreign Large-size Research Facility Application Supporting project and the Global Science Experimental Data Hub Center of the Korea Institute of Science and Technology Information; the Polish Ministry of Science and Higher Education and the National Science Center; the Ministry of Education and Science of the Russian Federation and the Russian Foundation for Basic Research; the Slovenian Research Agency; Ikerbasque, Basque Foundation for Science, Basque Government (No. IT956-16) and Ministry of Economy and Competitiveness (MINECO) (Juan de la Cierva), Spain; the Swiss National Science Foundation; the Ministry of Education and the Ministry of Science and Technology of Taiwan; and the United States Department of Energy and the National Science Foundation
A Comparative Study of Threshold-based Feature Selection Techniques
Abstract Given high-dimensional software measurement data, researchers and practitioners often use feature (metric) selection techniques to improve the performance of software quality classification models. This paper presents our newly proposed threshold-based feature selection techniques, comparing the performance of these techniques by building classification models using five commonly used classifiers. In order to evaluate the effectiveness of different feature selection techniques, the models are evaluated using eight different performance metrics separately since a given performance metric usually captures only one aspect of the classification performance. All experiments are conducted on three Eclipse data sets with different levels of class imbalance. The experiments demonstrate that the choice of a performance metric may significantly influence the results. In this study, we have found four distinct patterns when utilizing eight performance metrics to order 11 threshold-based feature selection techniques. Moreover, performances of the software quality models either improve or remain unchanged despite the removal of over 96% of the software metrics (attributes)
Observation of TransverseΛ= ̄ΛHyperon Polarization ine+e−Annihilation at Belle
We report the first observation of the spontaneous polarization of Lambda and (Lambda) over bar hyperons transverse to the production plane in e(+)e(-) annihilation, which is attributed to the effect arising from a polarizing fragmentation function. For inclusive Lambda/(Lambda) over bar production, we also report results with subtracted feed-down contributions from Sigma(0) and charm. This measurement uses a dataset of 800.4 fb(-1) collected by the Belle experiment at or near a center-of-mass energy of 10.58 GeV. We observe a significant polarization that rises with the fractional energy carried by the Lambda/(Lambda) over bar hyperon.We thank the KEKB group for the excellent operation of the accelerator; the KEK cryogenics group for the efficient operation of the solenoid; and the KEK computer group, and the Pacific Northwest National Laboratory (PNNL) Environmental Molecular Sciences Laboratory (EMSL) computing group for strong computing support; and the National Institute of Informatics, and Science Information NETwork 5 (SINET5) for valuable network support. We acknowledge support from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan, the Japan Society for the Promotion of Science (JSPS), and the Tau-Lepton Physics Research Center of Nagoya University; the Australian Research Council including Grants No. DP180102629, No. DP170102389, No. DP170102204, No. DP150103061, No. FT130100303; Austrian Science Fund under Grant No. P 26794-N20; the National Natural Science Foundation of China under Contracts No. 11435013, No. 11475187, No. 11521505, No. 11575017, No. 11675166, No. 11705209; Key Research Program of Frontier Sciences, Chinese Academy of Sciences (CAS), Grant No. QYZDJ-SSW-SLH011; the CAS Center for Excellence in Particle Physics (CCEPP); the Shanghai Pujiang Program under Grant No. 18PJ1401000; the Ministry of Education, Youth and Sports of the Czech Republic under Contract No. LTT17020; the Carl Zeiss Foundation, the Deutsche Forschungsgemeinschaft, the Excellence Cluster Universe, and the VolkswagenStiftung; the Department of Science and Technology of India; the Istituto Nazionale di Fisica Nucleare of Italy; National Research Foundation (NRF) of Korea Grants No. 2015H1A2A1033649, No. 2016R1D1A1B01010135, No. 2016K1A3A7A09005 603, No. 2016R1D1A1B02012900, No. 2018R1A2B3003 643, No. 2018R1A6A1A06024970, No. 2018R1D1 A1B07047294; Radiation Science Research Institute, Foreign Large-size Research Facility Application Supporting project, the Global Science Experimental Data Hub Center of the Korea Institute of Science and Technology Information and KREONET/GLORIAD; the Polish Ministry of Science and Higher Education and the National Science Center; the Grant of the Russian Federation Government, Agreement No. 14.W03.31.0026; the Slovenian Research Agency; Ikerbasque, Basque Foundation for Science, Spain; the Swiss National Science Foundation; the Ministry of Education and the Ministry of Science and Technology of Taiwan; and the United States Department of Energy and the National Science Foundation
An AUC-based Permutation Variable Importance Measure for Random Forests
The random forest (RF) method is a commonly used tool for classification with high dimensional data as well as for ranking candidate predictors based on the so-called random forest variable importance measures (VIMs). However the classification performance of RF is known to be suboptimal in case of strongly unbalanced data, i.e. data where response class sizes differ considerably. Suggestions were made to obtain better classification performance based either on sampling procedures or on cost sensitivity analyses. However to our knowledge the performance of the VIMs has not yet been examined in the case of unbalanced response classes. In this paper we explore the performance of the permutation VIM for unbalanced data settings and introduce an alternative permutation VIM based on the area under the curve (AUC) that is expected to be more robust towards class imbalance. We investigated the performance of the standard permutation VIM and of our novel AUC-based permutation VIM for different class imbalance levels using simulated data and real data. The results suggest that the standard permutation VIM loses its ability to discriminate between associated predictors and predictors not associated with the response for increasing class imbalance. It is outperformed by our new AUC-based permutation VIM for unbalanced data settings, while the performance of both VIMs is very similar in the case of balanced classes. The new AUC-based VIM is implemented in the R package party for the unbiased RF variant based on conditional inference trees. The codes implementing our study are available from the companion website: http://www.ibe.med.uni-muenchen.de/organisation/mitarbeiter/070_drittmittel/janitza/index.html
Instantaneous interaction in massive gravity
In general relativity, the instantaneous contributions to the gravitational
potentials cancel each other in observable, leaving the theory free of physical
instantaneous interactions. In models where these subtle cancellations are
spoiled by the presence of fields that break Lorentz invariance, physical
instantaneous interactions are possible. Such interactions are studied for a
model of Lorentz- violating massive gravity
Trade patterns facilitating highly pathogenic avian influenza virus dissemination in the free-grazing layer duck system in Vietnam
Highly pathogenic avian influenza (HPAI) viruses continue to threaten smallholder poultry producers in several South‐east Asian countries, including Vietnam. In particular, the free‐grazing duck system has been repeatedly highlighted as a major risk factor for HPAI outbreaks. Free‐grazing ducks, which scavenge on rice paddies after the harvest, account for a large proportion of the duck population in Vietnam and the wider South‐east Asian region. However, the structure and dynamics of the free‐grazing duck production from farm to consumption has not been described for Vietnam. In this study, we used a value chain approach to provide a complete picture of the actors involved in the production and marketing of free‐grazing duck eggs and spent layer ducks, as well as to investigate the governance structure of this food system. Group interviews and key informant interviews were conducted in two provinces located in the Mekong River Delta (MRD) and the Red River Delta (RRD). The results presented here highlight similarities and differences in farming and trade practices between the two provinces. The trade of spent layer ducks involved large volumes of live ducks being sent to China and Cambodia for consumption, generating a substantial risk of transboundary spread of pathogens, including HPAI viruses. We describe the major role of “duck yards”, which act as hubs in the northbound trade of spent layer ducks. These yards should be considered as essential links in the value chain of spent layer ducks when considering HPAI surveillance and control. The veterinary authorities are only marginally involved in the value chain activities, and their influence could be strengthened by increasing surveillance activities for instance in duck yards. Last, we discuss the dynamics of the duck value chain and further implications for future HPAI management policies
Cancer chemotherapy in early life significantly alters the maturation of pain processing
Advances in paediatric cancer treatment have led to a ten year survival rate greater than 75%. Platinum-based chemotherapies (e.g.cisplatin) induce peripheral sensory neuropathy in adult and paedriatric cancer patients. The period from birth through to adulthood represents a period of maturation within nociceptive systems. Here we investigated how cisplatin impacts upon postnatal maturation of nociceptive systems. Neonatal Wistar rats (Postnatal day (P) 7) were injected (i.p.) daily with either vehicle (PBS) or cisplatin (1mg/kg) for five consecutive days. Neither group developed mechanical or thermal hypersensitivity immediately during or after treatment. At P22 the cisplatin group developed mechanical (P<0.05) and thermal (P<0.0001) hypersensitivity versus vehicle group. Total DRG or dorsal horn neuronal number did not differ at P45, however there was an increase in intraepidermal nerve fibre density in cisplatin treated animals at this age. The percentage of IB4+ve, CGRP+ve and NF200+ve DRG neurons was not different between groups at P45. There was an increase in TrkA+ve DRG neurons in the cisplatin group at P45, in addition to increased TrkA, NF200 and vGLUT2 immunoreactivity in the lumbar dorsal horn versus controls. These data highlight the impact paediatric cancer chemotherapy has upon the maturation of pain pathways and later life pain experience
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