Possible DDˉD\bar{D} and BBˉB\bar{B} Molecular states in a chiral quark model

We perform a systematic study of the bound state problem of $D\bar{D}$ and $B\bar{B}$ systems by using effective interaction in our chiral quark model. Our results show that both the interactions of $D\bar{D}$ and $B\bar{B}$ states are attractive, which consequently result in $I^G(J^{PC})=0^+(0^{++})$ $D\bar{D}$ and $B\bar{B}$ bound states.Comment: arXiv admin note: substantial text overlap with arXiv:1204.395

Prospects of cold dark matter searches with an ultra-low-energy germanium detector

The report describes the research program on the development of ultra-low-energy germanium detectors, with emphasis on WIMP dark matter searches. A threshold of 100 eV is achieved with a 20 g detector array, providing a unique probe to the low-mas WIMP. Present data at a surface laboratory is expected to give rise to comparable sensitivities with the existing limits at the $\rm{5 - 10 GeV}$ WIMP-mass range. The projected parameter space to be probed with a full-scale, kilogram mass-range experiment is presented. Such a detector would also allow the studies of neutrino-nucleus coherent scattering and neutrino magnetic moments.Comment: 3 pages, 4 figures, Proceedings of TAUP-2007 Conferenc

Prescription Patterns of Antidementia and Psychotropic Drugs in People Living With Dementia: Findings From the Clinical Pathway Study of Alzheimer's Disease in China

OBJECTIVES: Evidence about prescribing patterns of dementia medication in China is lacking. This study aimed to examine prescribing rates of antidementia and psychotropic drugs and factors associated with drug prescription for dementia in China. DESIGN: A multicenter observational study. SETTING AND PARTICIPANTS: This study employed cross-sectional data from the Clinical Pathway for Alzheimer's Disease in China study that was conducted in 28 memory clinics at tertiary hospitals across 14 provinces between 2012 and 2013. Patients aged ≥45 years with a diagnosis of dementia were included. METHODS: Antidementia and psychotropic drugs were classified according to the Anatomical Therapeutic Chemical codes. Odds ratios (ORs) of putative factors associated with prescription patterns were estimated using logistic regressions. RESULTS: A total of 751 respondents were included in this study, 77.8% of whom were prescribed antidementia drugs, and 33.0% were prescribed at least 1 psychotropic drug. The concomitant prescription rate of antidementia and psychotropic drugs was 24.1%. Frontotemporal dementia [OR 9.92 (99.17% CI 3.08-42.70)], severe dementia [4.25 (1.88-9.79)], and apathy [1.94 (1.18-3.20)] were significantly associated with an elevated likelihood of memantine prescription. Psychotic symptoms [1.84 (1.02-3.35)], agitation [1.91 (1.08-3.40)], and depressive symptoms [2.10 (1.12-3.94)] were significantly associated with the coprescription of antidementia and psychotropic agents. CONCLUSIONS AND IMPLICATIONS: The prescribing rate of antidementia drugs in the study sample was higher, whereas the rate of coprescription of psychotropic and antidementia drugs was lower than reported in Western studies. Dementia prescription practice was generally consistent with clinical guidelines in memory clinics in China, whereas the prescription of antidementia and psychotropic medication mainly depended on patients’ clinical symptoms

Quantum kinetic description of Coulomb effects in one-dimensional nano-transistors

In this article, we combine the modified electrostatics of a one-dimensional transistor structure with a quantum kinetic formulation of Coulomb interaction and nonequilibrium transport. A multi-configurational self-consistent Green's function approach is presented, accounting for fluctuating electron numbers. On this basis we provide a theory for the simulation of electronic transport and quantum charging effects in nano-transistors, such as gated carbon nanotube and whisker devices and one-dimensional CMOS transistors. Single-electron charging effects arise naturally as a consequence of the Coulomb repulsion within the channel

Measurement of Cosmic-ray Muons and Muon-induced Neutrons in the Aberdeen Tunnel Underground Laboratory

We have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be $I_{\mu} = (5.7 \pm 0.6) \times 10^{-6}$ cm$^{-2}$s$^{-1}$sr$^{-1}$. The yield of muon-induced neutrons in the liquid scintillator was determined to be $Y_{n} = (1.19 \pm 0.08 (stat) \pm 0.21 (syst)) \times 10^{-4}$ neutrons/($\mu\cdot$g$\cdot$cm$^{-2}$). A fit to the recently measured neutron yields at different depths gave a mean muon energy dependence of $\left\langle E_{\mu} \right\rangle^{0.76 \pm 0.03}$ for liquid-scintillator targets.Comment: 14 pages, 17 figures, 3 table

Anomalous Optoelectronic Properties of Chiral Carbon Nanorings...and One Ring to Rule Them All

Carbon nanorings are hoop-shaped, {\pi}-conjugated macrocycles which form the fundamental annular segments of single-walled carbon nanotubes (SWNTs). In a very recent report, the structures of chiral carbon nanorings (which may serve as chemical templates for synthesizing chiral nanotubes) were experimentally synthesized and characterized for the first time. Here, in our communication, we show that the excited-state properties of these unique chiral nanorings exhibit anomalous and extremely interesting optoelectronic properties, with excitation energies growing larger as a function of size (in contradiction with typical quantum confinement effects). While the first electronic excitation in armchair nanorings is forbidden with a weak oscillator strength, we find that the same excitation in chiral nanorings is allowed due to a strong geometric symmetry breaking. Most importantly, among all the possible nanorings synthesized in this fashion, we show that only one ring, corresponding to a SWNT with chiral indices (n+3,n+1), is extremely special with large photoinduced transitions that are most readily observable in spectroscopic experiments.Comment: Accepted by the Journal of Physical Chemistry Letter

Superlattices of Bi2Se3/In2Se3: Growth Characteristics and Structural Properties

Superlattices (SLs) consisted of alternating Bi2Se3 and In2Se3 layers are grown on Si(111) by molecular-beam epitaxy. Bi2Se3, a three-dimensional topological insulator (TI), showed good chemical and structural compatibility with In2Se3, a normal band insulator with large energy bandgap. The individual layers in the SLs are very uniform and the hetero-interfaces are sharp. Therefore, such SL structures are potential candidates for explorations of the quantum size effects of TIs

Van der Waals epitaxy of Bi2Se3 on Si(111) vicinal surface: An approach to prepare high-quality thin films of topological insulator

Epitaxial growth of topological insulator Bi2Se3 thin films on nominally flat and vicinal Si(111) substrates is studied. In order to achieve planner growth front and better quality epifilms, a two-step growth method is adopted for the van der Waal epitaxy of Bi2Se3 to proceed. By employing vicinal Si(111) substrate surfaces, the in-pane growth rate anisotropy of Bi2Se3 is explored to achieve single crystalline Bi2Se3 epifilms, in which threading defects and twins are effectively suppressed. Optimization of the growth parameters has resulted in vicinal Bi2Se3 films showing a carrier mobility of ~ 2000 cm2V-1s-1 and the background doping of ~ 3 x 1018 cm-3 of the as-grown layers. Such samples not only show relatively high magnetoresistance but also a linear dependence on magnetic field.Comment: 18 pages, 4 figure