800 research outputs found
Present Limits on the Precision of SM Predictions for Jet Energies
We investigate the impact of theoretical uncertainties on the accuracy of
measurements involving hadronic jets. The analysis is performed using events
with a Z boson and a single jet observed in collisions at
= 1.96 TeV in 4.6 of data from the Collider Detector at
Fermilab (CDF). The transverse momenta (\pt) of the jet and the boson should
balance each other due to momentum conservation in the plane transverse to the
direction of the and beams. We evaluate the dependence of the
measured \pt-balance on theoretical uncertainties associated with initial and
final state radiation, choice of renormalization and factorization scales,
parton distribution functions, jet-parton matching, calculations of matrix
elements, and parton showering. We find that the uncertainty caused by parton
showering at large angles is the largest amongst the listed uncertainties. The
proposed method can be re-applied at the LHC experiments to investigate and
evaluate the uncertainties on the predicted jet energies. The distributions
produced at the CDF environment are intended for comparison to those from
modern event generators and new tunes of parton showering.Comment: Submitted to Nucl. Instr. and Meth.
Rumikiru, n. gen. (Scorpiones: Bothriuridae), a new scorpion genus from the Atacama Desert
Rumikiru, n. gen., a new bothriurid scorpion genus from the coastal Atacama Desert, Chile, is described. This is the first scorpion genus endemic to northern Chile. It is most closely related to Pachakutej Ochoa, 2004, from the inter-Andean valleys of Peru. Orobothriurus lourencoi Ojanguren-Affilastro, 2003, is transferred to the new genus and redescribed, creating Rumikiru lourencoi (Ojanguren-Affilastro, 2003), n. comb., and a second species of the genus, Rumikiru atacama, n. sp., is described.Fil: Ojanguren Affilastro, Andres Alejandro. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Mattoni, Camilo Ivan. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas, FĂsicas y Naturales. CĂĄtedra de Diversidad Animal I; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Ochoa, JosĂ© A.. Universidade de Sao Paulo; Brasil. Universidad Nacional de San Antonio Abad del Cusco. Museo de Historia Natural; PerĂșFil: Prendini, Lorenzo. American Museum Of Natural History; Estados Unido
Tuberculosis control in prisons: current situation and research gaps
Background: Tuberculosis (TB) in penitentiary services (prisons) is a major challenge to TB control. This review article describes the challenges that prison systems encounter in TB control and provides solutions for the more efficient use of limited resources based on the three pillars of the post-2015 End TB Strategy. This paper also proposes research priorities for TB control in prisons based on current challenges.
Methods: Articles (published up to 2011) included in a recent systematic review on TB control in prisons were further reviewed. In addition, relevant articles in English (published 1990 to May 2014) were identified by searching keywords in PubMed and Google Scholar. Article bibliographies and conference abstracts were also hand-searched.
Results: Despite being a serious cause of morbidity and mortality among incarcerated populations, many prison systems encounter a variety of challenges that hinder TB control. These include, but are not limited to, insufficient laboratory capacity and diagnostic tools, interrupted supply of medicines, weak integration between civilian and prison TB services, inadequate infection control measures, and low policy priority for prison healthcare.
Conclusions: Governmental commitment, partnerships, and sustained financing are needed in order to facilitate improvements in TB control in prisons, which will translate to the wider community
Contrasting Phaseolus crop water use patterns and stomatal dynamics in response to terminal drought
Terminal drought stress affects more than half of the areas planted with common bean (Phaseolus vulgaris), the main food legume globally, generating severe yield losses. Phenotyping water deficit responses and water use are central strategies to develop improved terminal drought resilience. The exploration and exploitation of genetic diversity in breeding programs are gaining importance, with a particular interest in related species with great adaptation to biotic and abiotic factors. This is the case with tepary beans (Phaseolus acutifolius), a bean that evolved and was domesticated in arid conditions and is considered well adapted to drought and heat stress. Under greenhouse conditions, using one genotype of tepary beans (resistant to drought) and two of common beans (one resistant and one susceptible to terminal drought), we evaluated phenotypic differences in traits such as water use efficiency (WUE), transpiration efficiency, rate of photosynthesis, photosynthetic efficiency, stomatal density, stomatal index, stomatal size, and the threshold for transpiration decline under well-watered and terminal drought conditions. Our results indicate two different water use strategies in drought-resistant genotypes: one observed in common bean aimed at conserving soil water by closing stomata early, inhibiting stomatal development, and limiting growth; and the other observed in tepary bean, where prolonged stomatal opening and higher carbon fixation, combined with no changes in stomata distribution, lead to higher biomass accumulation. Strategies that contribute to drought adaptation combined with other traits, such as greater mobilization of photoassimilates to the formation of reproductive structures, confer bean drought resistance and are useful targets in breeding programs
On the mechanisms of heavy-quarkonium hadroproduction
We discuss the various mechanisms potentially at work in hadroproduction of
heavy quarkonia in the light of computations of higher-order QCD corrections
both in the Colour-Singlet (CS) and Colour-Octet (CO) channels and the
inclusion of the contribution arising from the s-channel cut in the CS channel.
We also discuss new observables meant to better discriminate between these
different mechanisms.Comment: Invited review talk at 3rd International Conference On Hard And
Electromagnetic Probes Of High-Energy Nuclear Collisions (HP2008), 8-14 June
2008, Illa da Toxa, Galicia, Spain. 11 pages, 21 figures, LaTeX, uses
svjour.cls and svepj.clo (included
Associated production of light gravitinos in e^+e^- and e^-\gamma collisions
Light gravitino productions in association with a neutralino (selectron) in
e^+e^- (e^-\gamma) collisions are restudied in a scenario that the lightest
supersymmetric particle is a gravitino and the produced neutralino (selectron)
promptly decays into a photon (electron) and a gravitino. We explicitly give
the helicity amplitudes for the production processes by using the effective
goldstino interaction Lagrangian, and present the cross sections with different
collision energies and mass spectra. We also examine selection efficiencies by
kinematical cuts and beam polarizations for the signal and background
processes, and show that the energy and angular distributions of the photon
(electron) can explore the mass of the t-channel exchange particle as well as
the mass of the decaying particle at a future e^+e^- (e^-\gamma) collider.Comment: 12 pages, 12 figures, 4 tables; references added, version to appear
in EPJ
Colour reconnections in Herwig++
We describe the implementation details of the colour reconnection model in
the event generator Herwig++. We study the impact on final-state observables in
detail and confirm the model idea from colour preconfinement on the basis of
studies within the cluster hadronization model. Moreover, we show that the
description of minimum bias and underlying event data at the LHC is improved
with this model and present results of a tune to available data.Comment: 19 pages, 21 figures, 2 tables. Matches with published versio
Final report on the CCPR Key Comparison CCPR-K3.2014 Luminous Intensity
Main text The metrological equivalence of national measurement standards in the field of photometry and radiometry is determined by a set of key comparisons chosen and organised by the Consultative Committee of Photometry and Radiometry (CCPR) of the Comité international des poids et mesures (CIPM), working closely with the Regional Metrology Organisations (RMOs). In September 2009 the CCPR decided that a second round of the key comparison K3 Luminous Intensity be commenced. The National Research Council of Canada (NRC) was chosen to pilot this comparison. A total of 12 participants were selected from the three RMO group members: EURAMET&COOMET (6: IO-CSIC, LNE-CNAM, METAS, NPL, PTB, VNIIOFI), APMP&AFRIMETS (4: NMISA, NIM, NMIA, NMIJ), and SIM (2: NIST, NRC). The comparison was organised as a star comparison (NMI-Pilot-NMI) using incandescent standard lamps supplied by each NMI (National Metrology Institute) as the travelling comparison artifact. This report describes the comparison organisation (Section 2), the measurement methods and uncertainties achieved at all the participants and at the pilot (Sections 3 and 4), and the method for analysis and the results of the comparison according to this method (Section 4). It includes a comparison of the results of this comparison with the 1999 first round key comparison (Section 5). Section 6 presents a summary of the comparison. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA)
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair
Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt(s)=1.96 TeV using Lepton + Jets Events with Lifetime b-tagging
We present a measurement of the top quark pair () production cross
section () in collisions at TeV
using 230 pb of data collected by the D0 experiment at the Fermilab
Tevatron Collider. We select events with one charged lepton (electron or muon),
missing transverse energy, and jets in the final state. We employ
lifetime-based b-jet identification techniques to further enhance the
purity of the selected sample. For a top quark mass of 175 GeV, we
measure pb, in
agreement with the standard model expectation.Comment: 7 pages, 2 figures, 3 tables Submitted to Phys.Rev.Let
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