3,345 research outputs found
Inclusive double-quarkonium production at the Large Hadron Collider
Based on the nonrelativistic QCD (NRQCD) factorization formalism, we
investigate inclusive productions of two spin-triplet S-wave quarkonia
pp->2J/psi+X, 2Upsilon+X, and J/psi+Upsilon+X at the CERN Large Hadron
Collider. The total production rates integrated over the rapidity (y) and
transverse-momentum (p_T) ranges |y|<2.4 and p_T<50 GGeV are predicted to be
sigma[pp->2J/psi+X] = 22 (35) nb, sigma[pp->2Upsilon+X] = 24 (49) pb, and
sigma[pp->J/psi+Upsilon+X] = 7 (13) pb at the center-of-momentum energy sqrt{s}
= 7 (14) TeV. In order to provide predictions that can be useful in both small-
and large-p_T regions, we do not employ the fragmentation approximation and we
include the spin-triplet S-wave color-singlet and color-octet channels for each
quarkonium final state at leading order in the strong coupling. The p_T
distributions of pp->2J/psi+X and 2Upsilon+X in the low-p_T region are
dominated by the color-singlet contributions. At leading order in the strong
coupling, the color-singlet channel is absent for pp->J/psi+Upsilon+X.
Therefore, the process pp->J/psi+Upsilon+X may provide a useful probe to the
color-octet mechanism of NRQCD.Comment: 26 pages, 7 figures, 3 tables, version published in JHE
Implementation of a comprehensive intervention for patients at high risk of cardiovascular disease in rural China: A pragmatic cluster randomized controlled trial
Objective: This study aims to assess whether a standard intervention package of cardiovascular disease (CVD) care was being delivered effectively, and if it was associated with improved lifestyle and biomedical indicators. Methods: In rural China, we implemented a pragmatic cluster randomized controlled trial for 12 months, randomized at the township hospital level, and compared with usual care. Intervention case management guideline, training and performance monitoring meeting and patient support activities were designed to fit within the job description of family doctors in the township hospitals and comprised: 1) prescription of a standardised package of medicines targeted at those with hypertension or diabetes; 2) advice about specific lifestyle interventions; and 3) advice about medication adherence. Participants were 50-74 years old, had hypertension and CVD risk scores >20% or diabetes, but were excluded if a history of severe CVD events. We also randomly selected 100 participants from six selected clusters per arm as a panel to collect intermediate biomedical indicators over time. Results: A total of 28,130 participants, in 33 intervention and 34 control township hospitals, were recruited. Compared with the control arm, participants in the intervention arm had substantially improved prescribing rates of anti-hypertensives, statins and aspirin (P0.05). Conclusion: Implementation of the package by family doctors was feasible and improved prescribing and some lifestyle changes. Additional measures such as reducing medication costs and patient education are required. Trial registration: Current Controlled Trials ISRCTN58988083
A Chinese immigrant paradox? Low coronary heart disease incidence but higher short?term mortality in western?dwelling Chinese immigrants: a systematic review and meta?analysis.
Background-—Chinese form a large proportion of the immigrant population in Western countries. There is evidence that Chineseimmigrants experience an increased risk of coronary heart disease (CHD) after immigration in part due to cultural habits andacculturation. This is the first systematic review and meta-analysis that aims to examine the risk of CHD in people of Chineseethnicity living in Western countries, in comparison with whites and another major immigrant group, South Asians.Methods and Results-—Literature on the incidence, mortality, and prognosis of CHD among Chinese living in Western countrieswas searched systematically in any language using 6 electronic databases up to December 2014. Based on the meta-analysis,Chinese had lower incidence of CHD compared with whites (odds ratio 0.29; 95% CI: 0.24–0.34) and South Asians (odds ratio 0.37;95% CI: 0.24–0.57) but higher short-term mortality after first hospitalization for acute myocardial infarction compared with whites(odds ratio 1.34; 95% CI, 1.04–1.73) and South Asians (odds ratio 1.82; 95% 1.33–2.50). There was no significant differencebetween Chinese immigrants and whites in long-term outcomes (mortality and recurrent events) after acute myocardial infarction.Conclusions-—These findings provide an important focus for resource planning to enhance early secondary prevention of CHD toimprove short-term survival outcomes among Western-dwelling Chinese immigrants
Antimony-doped graphene nanoplatelets
Heteroatom doping into the graphitic frameworks have been intensively studied for the development of metal-free electrocatalysts. However, the choice of heteroatoms is limited to non-metallic elements and heteroatom-doped graphitic materials do not satisfy commercial demands in terms of cost and stability. Here we realize doping semimetal antimony (Sb) at the edges of graphene nanoplatelets (GnPs) via a simple mechanochemical reaction between pristine graphite and solid Sb. The covalent bonding of the metalloid Sb with the graphitic carbon is visualized using atomic-resolution transmission electron microscopy. The Sb-doped GnPs display zero loss of electrocatalytic activity for oxygen reduction reaction even after 100,000 cycles. Density functional theory calculations indicate that the multiple oxidation states (Sb3+ and Sb5+) of Sb are responsible for the unusual electrochemical stability. Sb-doped GnPs may provide new insights and practical methods for designing stable carbon-based electrocatalystsclose0
Serial optical coherence microscopy for label-free volumetric histopathology
The observation of histopathology using optical microscope is an essential procedure for examination of tissue biopsies or surgically excised specimens in biological and clinical laboratories. However, slide-based microscopic pathology is not suitable for visualizing the large-scale tissue and native 3D organ structure due to its sampling limitation and shallow imaging depth. Here, we demonstrate serial optical coherence microscopy (SOCM) technique that offers label-free, high-throughput, and large-volume imaging of ex vivo mouse organs. A 3D histopathology of whole mouse brain and kidney including blood vessel structure is reconstructed by deep tissue optical imaging in serial sectioning techniques. Our results demonstrate that SOCM has unique advantages as it can visualize both native 3D structures and quantitative regional volume without introduction of any contrast agents
Engineering of quantum dot photon sources via electro-elastic fields
The possibility to generate and manipulate non-classical light using the
tools of mature semiconductor technology carries great promise for the
implementation of quantum communication science. This is indeed one of the main
driving forces behind ongoing research on the study of semiconductor quantum
dots. Often referred to as artificial atoms, quantum dots can generate single
and entangled photons on demand and, unlike their natural counterpart, can be
easily integrated into well-established optoelectronic devices. However, the
inherent random nature of the quantum dot growth processes results in a lack of
control of their emission properties. This represents a major roadblock towards
the exploitation of these quantum emitters in the foreseen applications. This
chapter describes a novel class of quantum dot devices that uses the combined
action of strain and electric fields to reshape the emission properties of
single quantum dots. The resulting electro-elastic fields allow for control of
emission and binding energies, charge states, and energy level splittings and
are suitable to correct for the quantum dot structural asymmetries that usually
prevent these semiconductor nanostructures from emitting polarization-entangled
photons. Key experiments in this field are presented and future directions are
discussed.Comment: to appear as a book chapter in a compilation "Engineering the
Atom-Photon Interaction" published by Springer in 2015, edited by A.
Predojevic and M. W. Mitchel
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Improved Constraints on Sterile Neutrino Mixing from Disappearance Searches in the MINOS, MINOS+, Daya Bay, and Bugey-3 Experiments.
Searches for electron antineutrino, muon neutrino, and muon antineutrino disappearance driven by sterile neutrino mixing have been carried out by the Daya Bay and MINOS+ collaborations. This Letter presents the combined results of these searches, along with exclusion results from the Bugey-3 reactor experiment, framed in a minimally extended four-neutrino scenario. Significantly improved constraints on the θ_{μe} mixing angle are derived that constitute the most constraining limits to date over five orders of magnitude in the mass-squared splitting Δm_{41}^{2}, excluding the 90% C.L. sterile-neutrino parameter space allowed by the LSND and MiniBooNE observations at 90% CL_{s} for Δm_{41}^{2}<13 eV^{2}. Furthermore, the LSND and MiniBooNE 99% C.L. allowed regions are excluded at 99% CL_{s} for Δm_{41}^{2}<1.6 eV^{2}
Multiferroicity in atomic van der Waals heterostructures
Materials that are simultaneously ferromagnetic and ferroelectric - multiferroics - promise the control of disparate ferroic orders, leading to technological advances in microwave magnetoelectric applications and next generation of spintronics. Single-phase multiferroics are challenged by the opposite d-orbital occupations imposed by the two ferroics, and heterogeneous nanocomposite multiferroics demand ingredients' structural compatibility with the resultant multiferroicity exclusively at inter-materials boundaries. Here we propose the two-dimensional heterostructure multiferroics by stacking up atomic layers of ferromagnetic Cr2Ge2Te6 and ferroelectric In2Se3, thereby leading to all-atomic multiferroicity. Through first-principles density functional theory calculations, we find as In2Se3 reverses its polarization, the magnetism of Cr2Ge2Te6 is switched, and correspondingly In2Se3 becomes a switchable magnetic semiconductor due to proximity effect. This unprecedented multiferroic duality (i.e., switchable ferromagnet and switchable magnetic semiconductor) enables both layers for logic applications. Van der Waals heterostructure multiferroics open the door for exploring the low-dimensional magnetoelectric physics and spintronic applications based on artificial superlattices
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