Two-hole bound states in modified t-J model

We consider modified $t-J$ model with minimum of single-hole dispersion at the points $(0,\pm \pi)$, $(\pm \pi,0)$. It is shown that two holes on antiferromagnetic background produce a bound state which properties strongly differs from the states known in the unmodified $t-J$ model. The bound state is d-wave, it has four nodes on the face of the magnetic Brillouin zone. However, in the coordinate representation it looks like as usual s-wave.Comment: LaTeX 9 page

Excitation spectrum and ground state properties of the S=1/2 Heisenberg ladder with staggered dimerization

We have studied the excitation spectrum of the $S=1/2$ quantum spin ladder with staggered dimerization by dimer series expansions, diagrammatic analysis of an effective interacting Bose gas of local triplets, and exact diagonalization of small clusters. We find that the model has two massive phases, with predominant inter-chain (rung) or intra-chain correlations. The transition from the rung dimer into the intra-chain dimer phase is characterized by softening of the triplet spectrum at $k=\pi$. The excitation spectrum as well as the spin correlations away from and close to the critical line are calculated. The location of the phase boundary is also determined.Comment: 13 pages, 7 figure

Dynamical spin correlations in Heisenberg ladder under magnetic field and correlation functions in SO(5) ladder

The zero-temperature dynamical spin-spin correlation functions are calculated for the spin-1/2 two-leg Heisenberg ladder in a magnetic field above the lower critical field Hc1. The dynamical structure factors are calculated which exhibit both massless and massive excitations. These modes appear in different sectors characterized by the parity in the rung direction and by the momentum in the direction of the chains. The structure factors have power-law singularities at the lower edges of their support. The results are also applicable to spin-1 Heisenberg chain. The implications are briefly discussed for various correlation functions and the pi-resonance in the SO(5) symmetric ladder model.Comment: 15 pages, 6 figures, added references; final version to appear in Phys. Rev.

Technology and Discourse: A Comparison of Face-to-face and Telephone Employment Interviews

Very little research has investigated the comparability of telephone and face-to-face employment interviews. This exploratory study investigated interviewers' questioning strategies and applicants' causal attributions produced during semi structured telephone and face-to-face graduate recruitment interviews (N=62). A total of 2044 causal attributions were extracted from verbatim transcripts of these 62 interviews. It was predicted that an absence of visual cues would lead applicants to produce, and interviewers to focus on, information that might reduce the comparative anonymity of telephone interviews. Results indicate that applicants produce more personal causal attributions in telephone interviews. Personal attributions are also associated with higher ratings in telephone, but not face-to-face interviews. In face-to-face interviews, applicants who attributed outcomes to more global causes received lower ratings. There was also a non-significant tendency for interviewers to ask more closed questions in telephone interviews. The implications of these findings for research and practice are discussed

Triggering Threshold Spacecraft Charging with Changes in Electron Emission from Materials

Modest changes in spacecraft charging conditions can lead to abrupt changes in the spacecraft equilibrium, from small positive potentials to large negative potentials relative to the space plasma; this phenomenon is referred to as threshold charging. It is well known that temporal changes of the space plasma environment (electron plasma temperature or density) can cause threshold charging. Threshold charging can also result from by temporal changes in the juxtaposition of the spacecraft to the environment, including spacecraft orbit, orientation, and geometry. This study focuses on the effects of possible changes in electron emission properties of representative spacecraft materials. It is found that for electron-induced emission, the possible threshold scenarios are very rich, since this type of electron emission can cause either positive or negative charging. Alternately, modification of photon- or ion-induced electron emission is found to induce threshold charging only in certain favorable cases. Changes of emission properties discussed include modifications due to: contamination, degradation and roughening of surfaces and layered materials; biasing and charge accumulation; bandstructure occupation and density of states caused by heat, optical or particle radiation; optical reflectivity and absorptivity; and inaccuracies and errors in measurements and parameterization of materials properties. An established method is used here to quantitatively gauge the relative extent to which these various changes in electron emission alter a spacecraft’s charging behavior and possibly lead to threshold charging. The absolute charging behavior of a hypothetical flat, two-dimensional satellite panel of a single material (either polycrystalline conductor Au or the polymeric polyimide Kapton™ H) is modeled as it undergoes modification and concomitant changes in spacecraft charging in three representative geosynchronous orbit environments, from full sunlight to full shade (eclipse) are considered

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Back-side emissions from filtered gold targets

An investigation of the rapid rise time of incoherent x-ray emission from targets heated by an ultra-short pulse (USP) high-intensity optical laser was conducted for use as the x-ray source for inner- shell photo-ionized (ISPI) x ray lasing. Previous studies considered front-side x-ray emission; however, ISPI x-ray lasing requires a filtered x-ray source. Modeling using the hydrodynamics/atomic kinetics code LASNEX of a 40 fs USP driving laser with an intensity of 10 exp(17W/CM2) incident on a flat target of thin Au layered on a Be filter is presented. The filter has a modest influence on the x- ray emission of the Au via conduction cooling but has a large effect on the backside spectrum by removing low energy x rays as the Au emission passes through the filter. The use of such a filtered source is shown to provide the needed x rays to achieve high gain in C at 45A

Recombination x-ray laser experiments using exploding ribbon Al targets

We present data obtained from recent recombination x-ray laser experiments carried out at the Nova and Phebus lasers using exploding ribbon Al targets irradiated with 100 ps pulses of 0.53-{mu}m light. Spatially and temporally resolved x-ray and soft x-ray spectra will be shown. These spectra revealed the plasma to be insufficiently ionized so as to produce inversions in H-like Al. Conditions were found to be appropriate for inversion in He- and Li-like Al, however, and evidence for amplification of the AlXI 105.7 {Angstrom} (5f-3d) and AlXII 88.9 (5f-3d) and 130.1 {Angstrom} (4f-3d) lines was seen. These results will be discussed in detail and related to other work regarding the discrepancies between expected and measured electron temperatures in plasmas of this type