3,602 research outputs found
Paramagnetic-diamagnetic interplay in quantum dots for non-zero temperatures
In the usual Fock-and Darwin-formalism with parabolic potential characterized
by the confining energy \eps_o := \hbar\omega_o= 3.37 meV, but including
explicitly also the Zeeman coupling between spin and magnetic field, we study
the combined orbital and spin magnetic properties of quantum dots in a
two-dimensional electron gas with parameters for GaAs, for N =1 and N >> 1
electrons on the dot.
For N=1 the magnetization M(T,B) consists of a paramagnetic spin contribution
and a diamagnetic orbital contribution, which dominate in a non-trivial way at
low temperature and fields rsp. high temperature and fields.
For N >> 1, where orbital and spin effects are intrinsically coupled in a
subtle way and cannot be separated, we find in a simplified Hartree
approximation that at N=m^2, i.e. at a half-filled last shell, M(T,B,N) is
parallel (antiparallel) to the magnetic field, if temperatures and fields are
low enough (high enough), whereas for N\ne m^2 the magnetization oscillates
with B and N as a T-dependent periodic function of the variable
x:=\sqrt{N}eB/(2m^*c\omega_o), with T-independent period \Delta x =1 (where m^*
:= 0.067 m_o is the small effective mass of GaAs, while m_o is the electron
mass). Correspondingly, by an adiabatic demagnetization process, which should
only be fast enough with respect to the slow transient time of the magnetic
properties of the dot, the temperature of the dot diminishes rsp. increases
with decreasing magnetic field, and in some cases we obtain quite pronounced
effects.Comment: LaTeX, 28 pages; including three .eps-figures; final version accepted
by J. Phys. CM, with minimal changes w.r.to v
Cross Section Ratios between different CM energies at the LHC: opportunities for precision measurements and BSM sensitivity
The staged increase of the LHC beam energy provides a new class of
interesting observables, namely ratios and double ratios of cross sections of
various hard processes. The large degree of correlation of theoretical
systematics in the cross section calculations at different energies leads to
highly precise predictions for such ratios. We present in this letter few
examples of such ratios, and discuss their possible implications, both in terms
of opportunities for precision measurements and in terms of sensitivity to
Beyond the Standard Model dynamics.Comment: 19 pages, 9 figure
Scedosporium and Pseudallescheria low molecular weight metabolites revealed by database search
The potential of mMass software search tool with new compound libraries was demonstrated on metabolomics of Scedosporium prolificans, S. apiospermum and Pseudallescheria boydii sensu stricto. Cyclic peptides pseudacyclins, small molecular weight tyroscherin analogues and various lipids were annotated by open source mass spectometry tool utilising accurate matrix-assisted laser desorption/ionisation mass spectral data of intact fungal spores. Electrospray ionisation combined with tandem mass spectrometry was used for monohexosylceramide characterisation in fungal extracts
Spectroscopy at B-factories Using Hard Photon Emission
The process of hard photon emission by initial electrons (positrons) at
B-factories is discussed. It is shown that studies of the bottomonium
spectroscopy will be feasible for the planned integrated luminosity of the
B-factory experiments.Comment: 9 pages, Latex, 1 fugure, Submitted to Int.Jour.Mod.Phys.
The suboptimal structures find the optimal RNAs: homology search for bacterial non-coding RNAs using suboptimal RNA structures
Non-coding RNAs (ncRNAs) are regulatory molecules encoded in the intergenic or intragenic regions of the genome. In prokaryotes, biocomputational identification of homologs of known ncRNAs in other species often fails due to weakly evolutionarily conserved sequences, structures, synteny and genome localization, except in the case of evolutionarily closely related species. To eliminate results from weak conservation, we focused on RNA structure, which is the most conserved ncRNA property. Analysis of the structure of one of the few well-studied bacterial ncRNAs, 6S RNA, demonstrated that unlike optimal and consensus structures, suboptimal structures are capable of capturing RNA homology even in divergent bacterial species. A computational procedure for the identification of homologous ncRNAs using suboptimal structures was created. The suggested procedure was applied to strongly divergent bacterial species and was capable of identifying homologous ncRNAs
Tagged-photon events in polarized DIS process
Deep-inelastic events for the scattering of the longitudinally polarized
electron by polarized proton with tagged collinear photon radiated from
initial-state electron are considered. The corresponding cross-section is
derived in the Born approximation. The model-independent radiative corrections
to the Born cross-section are also calculated. Obtained result is applied to
the case of elastic scattering.Comment: 14 pages, 2 figures, submitted to JET
Mexican-American perspectives on participation in clinical trials: A qualitative study
AbstractClinical trials are essential to advancing knowledge to reduce disease morbidity and mortality; however, ethnic and racial minorities remain under-represented in those studies. We explored knowledge and perceptions of clinical trials among Mexican-Americans in Texas. We conducted focus groups (NÂ =Â 128) stratified by gender, language preference, and geographical location. This paper presents four emergent, primary themes: 1) knowledge and understanding of clinical trials, 2) fears and concerns about participating, 3) perceived benefits of participating, and 4) incentives to participate. Results suggest that lack of knowledge and understanding of clinical trials leads to misunderstanding about research, including fears and lack of trust. Participants indicated that fears related to perceived experimentation, harm, immigration status, and lack of clinical trial opportunities within their communities were barriers to participation. On the other hand, free healthcare access, helping family members in the future, and monetary incentives could facilitate participation. We also found differences across themes by language, gender, and place of residence. Findings from our study could inform the development of interventions to enhance recruitment of Mexican-American participants into clinical trials
Public Participation in Scientific Research: a Framework for Deliberate Design
Members of the public participate in scientific research in many different contexts, stemming from traditions as varied as participatory action research and citizen science. Particularly in conservation and natural resource management contexts, where research often addresses complex socialâecological questions, the emphasis on and nature of this participation can significantly affect both the way that projects are designed and the outcomes that projects achieve. We review and integrate recent work in these and other fields, which has converged such that we propose the term public participation in scientific research (PPSR) to discuss initiatives from diverse fields and traditions. We describe three predominant models of PPSR and call upon case studies suggesting thatâregardless of the research contextâproject outcomes are influenced by (1) the degree of public participation in the research process and (2) the quality of public participation as negotiated during project design. To illustrate relationships between the quality of participation and outcomes, we offer a framework that considers how scientific and public interests are negotiated for project design toward multiple, integrated goals. We suggest that this framework and models, used in tandem, can support deliberate design of PPSR efforts that will enhance their outcomes for scientific research, individual participants, and socialâecological systems
Factors Related to Implementation and Reach of a Pragmatic Multisite Trial: The My Own Health Report (MOHR) Study
BACKGROUND: Contextual factors relevant to translating healthcare improvement interventions to different settings are rarely collected systematically. This study articulates a prospective method for assessing and describing contextual factors related to implementation and patient reach of a pragmatic trial in primary care.
METHODS: In a qualitative case-series, contextual factors were assessed from the My Own Health Report (MOHR) study, focused on systematic health risk assessments and goal setting for unhealthy behaviors and behavioral health in nine primary care practices. Practice staff interviews and observations, guided by a context template were conducted prospectively at three time points. Patient reach was calculated as percentage of patients completing MOHR of those who were offered MOHR and themes describing contextual factors were summarized through an iterative, data immersion process.These included practice members' motivations towards MOHR, practice staff capacity for implementation, practice information system capacity, external resources to support quality improvement, community linkages, and implementation strategy fit with patient populations.
CONCLUSIONS: Systematically assessing contextual factors prospectively throughout implementation of quality improvement initiatives helps translation to other health care settings. Knowledge of contextual factors is essential for scaling up of effective interventions
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