563 research outputs found
Condensed Matter Theory of Dipolar Quantum Gases
Recent experimental breakthroughs in trapping, cooling and controlling
ultracold gases of polar molecules, magnetic and Rydberg atoms have paved the
way toward the investigation of highly tunable quantum systems, where
anisotropic, long-range dipolar interactions play a prominent role at the
many-body level. In this article we review recent theoretical studies
concerning the physics of such systems. Starting from a general discussion on
interaction design techniques and microscopic Hamiltonians, we provide a
summary of recent work focused on many-body properties of dipolar systems,
including: weakly interacting Bose gases, weakly interacting Fermi gases,
multilayer systems, strongly interacting dipolar gases and dipolar gases in 1D
and quasi-1D geometries. Within each of these topics, purely dipolar effects
and connections with experimental realizations are emphasized.Comment: Review article; submitted 09/06/2011. 158 pages, 52 figures. This
document is the unedited author's version of a Submitted Work that was
subsequently accepted for publication in Chemical Reviews, copyright American
Chemical Society after peer review. To access the final edited and published
work, a link will be provided soo
A Study of Time-Dependent CP-Violating Asymmetries and Flavor Oscillations in Neutral B Decays at the Upsilon(4S)
We present a measurement of time-dependent CP-violating asymmetries in
neutral B meson decays collected with the BABAR detector at the PEP-II
asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The data
sample consists of 29.7 recorded at the
resonance and 3.9 off-resonance. One of the neutral B mesons,
which are produced in pairs at the , is fully reconstructed in
the CP decay modes , , , () and , or in flavor-eigenstate
modes involving and (). The flavor of the other neutral B meson is tagged at the time of
its decay, mainly with the charge of identified leptons and kaons. The proper
time elapsed between the decays is determined by measuring the distance between
the decay vertices. A maximum-likelihood fit to this flavor eigenstate sample
finds . The value of the asymmetry amplitude is determined from
a simultaneous maximum-likelihood fit to the time-difference distribution of
the flavor-eigenstate sample and about 642 tagged decays in the
CP-eigenstate modes. We find , demonstrating that CP violation exists in the neutral B meson
system. (abridged)Comment: 58 pages, 35 figures, submitted to Physical Review
Hearing aid effectiveness after aural rehabilitation - individual versus group (HEARING) trial: RCT design and baseline characteristics
<p>Abstract</p> <p>Background</p> <p>Hearing impairment is the most common body system disability in veterans. In 2008, nearly 520,000 veterans had a disability for hearing loss through the Department of Veterans Affairs (VA). Changes in eligibility for hearing aid services, along with the aging population, contributed to a greater than 300% increase in the number of hearing aids dispensed from 1996 to 2006. In 2006, the VA committed to having no wait times for patient visits while providing quality clinically-appropriate care. One approach to achieving this goal is the use of group visits as an alternative to individual visits. We sought to determine: 1) if group hearing aid fitting and follow-up visits were at least as effective as individual visits, and 2) whether group visits lead to cost savings through the six month period after the hearing aid fitting. We describe the rationale, design, and characteristics of the baseline cohort of the first randomized clinical trial to study the impact of group versus individual hearing aid fitting and follow-up visits.</p> <p>Methods</p> <p>Participants were recruited from the VA Puget Sound Health Care System Audiology Clinic. Eligible patients had no previous hearing aid use and monaural or binaural air-conduction hearing aids were ordered at the evaluation visit. Participants were randomized to receive the hearing aid fitting and the hearing aid follow-up in an individual or group visit. The primary outcomes were hearing-related function, measured with the first module of the Effectiveness of Aural Rehabilitation (Inner EAR), and hearing aid adherence. We tracked the total cost of planned and unplanned audiology visits over the 6-month interval after the hearing aid fitting.</p> <p>Discussion</p> <p>A cohort of 659 participants was randomized to receive group or individual hearing aid fitting and follow-up visits. Baseline demographic and self-reported health status and hearing-related measures were evenly distributed across the treatment arms.</p> <p>Outcomes after the 6-month follow-up period are needed to determine if group visits were as least as good as those for individual visits and will be reported in subsequent publication.</p> <p>Trial Registration</p> <p>NCT00260663</p
Measurement of the branching fraction and CP content for the decay B(0) -> D(*+)D(*-)
This is the pre-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2002 APS.We report a measurement of the branching fraction of the decay B0→D*+D*- and of the CP-odd component of its final state using the BABAR detector. With data corresponding to an integrated luminosity of 20.4 fb-1 collected at the Υ(4S) resonance during 1999–2000, we have reconstructed 38 candidate signal events in the mode B0→D*+D*- with an estimated background of 6.2±0.5 events. From these events, we determine the branching fraction to be B(B0→D*+D*-)=[8.3±1.6(stat)±1.2(syst)]×10-4. The measured CP-odd fraction of the final state is 0.22±0.18(stat)±0.03(syst).This work is supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF (Germany), INFN (Italy), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the A.P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
Measurement of D-s(+) and D-s(*+) production in B meson decays and from continuum e(+)e(-) annihilation at √s=10.6 GeV
This is the pre-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2002 APSNew measurements of Ds+ and Ds*+ meson production rates from B decays and from qq̅ continuum events near the Υ(4S) resonance are presented. Using 20.8 fb-1 of data on the Υ(4S) resonance and 2.6 fb-1 off-resonance, we find the inclusive branching fractions B(B⃗Ds+X)=(10.93±0.19±0.58±2.73)% and B(B⃗Ds*+X)=(7.9±0.8±0.7±2.0)%, where the first error is statistical, the second is systematic, and the third is due to the Ds+→φπ+ branching fraction uncertainty. The production cross sections σ(e+e-→Ds+X)×B(Ds+→φπ+)=7.55±0.20±0.34pb and σ(e+e-→Ds*±X)×B(Ds+→φπ+)=5.8±0.7±0.5pb are measured at center-of-mass energies about 40 MeV below the Υ(4S) mass. The branching fractions ΣB(B⃗Ds(*)+D(*))=(5.07±0.14±0.30±1.27)% and ΣB(B⃗Ds*+D(*))=(4.1±0.2±0.4±1.0)% are determined from the Ds(*)+ momentum spectra. The mass difference m(Ds+)-m(D+)=98.4±0.1±0.3MeV/c2 is also measured.This work was supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF (Germany), INFN (Italy), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the Swiss NSF, A. P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation
Integrating Quantitative Knowledge into a Qualitative Gene Regulatory Network
Despite recent improvements in molecular techniques, biological knowledge remains incomplete. Any theorizing about living systems is therefore necessarily based on the use of heterogeneous and partial information. Much current research has focused successfully on the qualitative behaviors of macromolecular networks. Nonetheless, it is not capable of taking into account available quantitative information such as time-series protein concentration variations. The present work proposes a probabilistic modeling framework that integrates both kinds of information. Average case analysis methods are used in combination with Markov chains to link qualitative information about transcriptional regulations to quantitative information about protein concentrations. The approach is illustrated by modeling the carbon starvation response in Escherichia coli. It accurately predicts the quantitative time-series evolution of several protein concentrations using only knowledge of discrete gene interactions and a small number of quantitative observations on a single protein concentration. From this, the modeling technique also derives a ranking of interactions with respect to their importance during the experiment considered. Such a classification is confirmed by the literature. Therefore, our method is principally novel in that it allows (i) a hybrid model that integrates both qualitative discrete model and quantities to be built, even using a small amount of quantitative information, (ii) new quantitative predictions to be derived, (iii) the robustness and relevance of interactions with respect to phenotypic criteria to be precisely quantified, and (iv) the key features of the model to be extracted that can be used as a guidance to design future experiments
Deployment of Water-based Liquid Scintillator in the Accelerator Neutrino Neutron Interaction Experiment
The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) is a 26-ton
water Cherenkov neutrino detector installed on the Booster Neutrino Beam (BNB)
at Fermilab. Its main physics goals are to perform a measurement of the neutron
yield from neutrino-nucleus interactions, as well as a measurement of the
charged-current cross section of muon neutrinos. An equally important focus is
placed on the research and development of new detector technologies and target
media. Specifically water-based liquid scintillator (WbLS) is of interest as a
novel detector medium, as it allows for the simultaneous detection of
scintillation and Cherenkov light. This paper presents the deployment of a 366L
WbLS vessel in ANNIE in March 2023 and the subsequent detection of both
Cherenkov light and scintillation from the WbLS. This proof-of-concept allows
for the future development of reconstruction and particle identification
algorithms in ANNIE, as well as dedicated analyses, such as the search for
neutral current events and the hadronic scintillation component within the WbLS
volume.Comment: 19 pages, 16 figure
Design, development and validation of a model of problem solving for Egyptian Science classes
Educators and policymakers envision the future of education in Egypt as enabling learners to acquire scientific inquiry and problem-solving skills. In this article, we describe the validation of a model for problem solving and the design of instruments for evaluating new teaching methods in Egyptian science classes. The instruments were based on an established model for problem solving and were designed to assess seventh grade students’ problem solving, experimental strategy knowledge, achievement and motivation towards science. The test for assessing students’ knowledge has been developed based on the topic, density and buoyancy which will be taught in seventh grade in a later intervention study. The instruments were partly self-developed and partly adapted from newly performed studies on strategy knowledge and problem solving in Germany. All instruments were translated into Arabic; the translation process and quality control are described. In order to determine the quality of the instruments, 44 students in Egypt completed the questionnaires and tests. The study’s aim to develop and validate the instruments did require an ad hoc and typical sample which was drawn from an accessible population. Accordingly, the characteristics of the sample are described. Data were analysed according to the classical test theory, but to underpin the results, the instruments were additionally analysed using the even stronger Rasch model. The findings demonstrated the reliability of the items and aspects of validity. In addition, this study showed how test items can be successfully developed and adapted in an international study and applied in a different language
Rationality as a Goal of Education
Abstract Those who believe education should involve more than learning facts often stress either (a) development or (b) thinking skills. A focus on development as a goal of education typically entails a conception of knowledge as organismic, holistic, and internally generated. In contrast, thinking skills programs commonly assume a mechanistic, reductionist perspective in which good thinking consists of some finite number of directly teachable skills. A conception of rationality as a goal of education is proposed that incorporates the complementary strengths and avoids the limitations of the developmental and thinking skills approaches. Rationality is defined as the self-reflective, intentional, and appropriate coordination and use of genuine reasons in generating and justifying beliefs and behavior. Philosophically, rationality is a justifiable goal of education, not only because it is a means to worthwhile ends but because it is an important end in itself and because it can be promoted via non-indoctrinative means. A psychological account of progressive rationality is provided that postulates continuing multiple interactions of (a) domain-specific developmental stages, (b) the learning of specific thinking skills, and (c) content-specific knowledge. Suggestions are made for fostering rationality at various educational levels. Finally, it is argued that the proposed conception of rationality as a goal of education complements and clarifies a variety of other educational goals
- …