28,940 research outputs found

    A new time-frequency method to reveal quantum dynamics of atomic hydrogen in intense laser pulses: Synchrosqueezing Transform

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    This study introduces a new adaptive time-frequency (TF) analysis technique, synchrosqueezing transform (SST), to explore the dynamics of a laser-driven hydrogen atom at an {\it ab initio} level, upon which we have demonstrated its versatility as a new viable venue for further exploring quantum dynamics. For a signal composed of oscillatory components which can be characterized by instantaneous frequency, the SST enables rendering the decomposed signal based on the phase information inherited in the linear TF representation with mathematical support. Compared with the classical type TF methods, the SST clearly depicts several intrinsic quantum dynamical processes such as selection rules, AC Stark effects, and high harmonic generation

    Study of carrier dynamics and radiative efficiency in InGaN/GaN LEDs with Monte Carlo method

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    In this paper, we have applied the Monte Carlo method to study carrier dynamics in InGaN quantum well. Vertical and lateral transport and its impact on device radiative efficiency is studied for different In compositions, dislocation densities, temperatures, and carrier densities. Our results show that the non‐radiative recombination caused by the defect trapping plays a dominating role for higher indium composition and this limits the internal quantum efficiency (IQE). For lower indium composition cases, carrier leakage plays some role in the mid to high injection conditions and carrier leakage is strong in very high carrier density in all cases. Our results suggest that reducing the trap density and QCSE are still the key factors to improve the IQE. The paper examines the relative roles of leakage and non‐radiative processes on IQE. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87087/1/2393_ftp.pd

    Depth, balancing, and limits of the Elo model

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    -Much work has been devoted to the computational complexity of games. However, they are not necessarily relevant for estimating the complexity in human terms. Therefore, human-centered measures have been proposed, e.g. the depth. This paper discusses the depth of various games, extends it to a continuous measure. We provide new depth results and present tool (given-first-move, pie rule, size extension) for increasing it. We also use these measures for analyzing games and opening moves in Y, NoGo, Killall Go, and the effect of pie rules

    The Impact of Customer Profile and Customer Participation on Customer Relationship Management Performance

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    There are two main sources of knowledge about customers: customer profile and customer participation. The companies use information technologies to analyze the customer profiles and extract tacit knowledge about customer via customer participation. The result of this experiment demonstrates that the use of customer profile improves customers’ perception on goods quality and increase the effectiveness of Customer Relationship Management (CRM). In addition, customer participation can improve customers’ perception on goods quality and enhance performance of CRM through perceived participation. The result indicates that the customer profiles and customer participation are two crucial factors for companies to maintain customer relationship

    PTPN11 Mutations in LEOPARD Syndrome: Report of Four Cases in Taiwan

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    Background/PurposeLEOPARD syndrome (LS) is a rare, autosomal dominant disorder. The typical clinical presentation includes multiple lentigines and cardiac defects. Mutation analysis of the PTPN11 gene is feasible. We report four cases of LS, which were confirmed by molecular genetic study.MethodsThe clinical features and mutations of the four patients were summarized.ResultsThe diagnosis of all four patients was made when lentigines appeared during childhood. Three cases had hypertrophic cardiomyopathy. No electrocardiographic conduction abnormality was noted in any of the cases. Three patients had hypertelorism and three had short stature. Two patients, identical twins, presented with the atypical phenotype of tongue protrusion and hepatosplenomegaly at birth. Twin B had mild mental retardation. Case 4 had moderate hearing impairment. Point mutation of the PTPN11 gene was found in all patients.ConclusionLS has typical skin manifestations. All patients should undergo a comprehensive examination, especially echocardiography and electrocardiography. The diagnosis can be confirmed by genetic study

    Percutaneous Endoscopic Gastrostomy in the Enteral Feeding of the Elderly

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    SummaryToday we are faced with an aging society that may develop malnutrition because of dysphagia related to dementia, stroke, and malignancy seen often in the elderly. The preferred form of nutritional supplementation for this group is enteral nutrition, and the most appropriate long-term method is by use of a gastrostomy. Percutaneous endoscopic gastrostomy (PEG) was first introduced in 1980 as an alternative to the traditional operative procedure and rapidly became the preferred procedure. In geriatric patients, the principal indications are neurological dysphagia and malnutrition, related to an underlying disease or anorexia-cachexia in very elderly. PEG is contraindicated in the presence of respiratory distress, previous gastric resection, total esophageal obstruction, coagulation disorders and sepsis in the elderly. Common complications include wound infection, leakage, hemorrhage, and fistula in the general population, but aspiration pneumonia is the major case of death in this group. Risks and complications of PEG must be discussed with patients and their families; and the decision for percutaneous endoscopic gastrostomy insertion should only be made after careful consideration and discussion between managing physicians, allied health professionals, and the patient and/or family. Four ethical principles may help make feeding decisions: beneficence, non-maleficence, autonomy and justice. Attentive long-term care after tube replacement is mandatory. Acceptance of percutaneous endoscopic gastrostomy placement by patients and their families tends to increase once favorable outcomes are offered

    Controlled Synthesis of Organic/Inorganic van der Waals Solid for Tunable Light-matter Interactions

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    Van der Waals (vdW) solids, as a new type of artificial materials that consist of alternating layers bonded by weak interactions, have shed light on fascinating optoelectronic device concepts. As a result, a large variety of vdW devices have been engineered via layer-by-layer stacking of two-dimensional materials, although shadowed by the difficulties of fabrication. Alternatively, direct growth of vdW solids has proven as a scalable and swift way, highlighted by the successful synthesis of graphene/h-BN and transition metal dichalcogenides (TMDs) vertical heterostructures from controlled vapor deposition. Here, we realize high-quality organic and inorganic vdW solids, using methylammonium lead halide (CH3NH3PbI3) as the organic part (organic perovskite) and 2D inorganic monolayers as counterparts. By stacking on various 2D monolayers, the vdW solids behave dramatically different in light emission. Our studies demonstrate that h-BN monolayer is a great complement to organic perovskite for preserving its original optical properties. As a result, organic/h-BN vdW solid arrays are patterned for red light emitting. This work paves the way for designing unprecedented vdW solids with great potential for a wide spectrum of applications in optoelectronics

    Ventricular divergence correlates with epicardial wavebreaks and predicts ventricular arrhythmia in isolated rabbit hearts during therapeutic hypothermia

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    INTRODUCTION: High beat-to-beat morphological variation (divergence) on the ventricular electrogram during programmed ventricular stimulation (PVS) is associated with increased risk of ventricular fibrillation (VF), with unclear mechanisms. We hypothesized that ventricular divergence is associated with epicardial wavebreaks during PVS, and that it predicts VF occurrence. METHOD AND RESULTS: Langendorff-perfused rabbit hearts (n = 10) underwent 30-min therapeutic hypothermia (TH, 30°C), followed by a 20-min treatment with rotigaptide (300 nM), a gap junction modifier. VF inducibility was tested using burst ventricular pacing at the shortest pacing cycle length achieving 1:1 ventricular capture. Pseudo-ECG (p-ECG) and epicardial activation maps were simultaneously recorded for divergence and wavebreaks analysis, respectively. A total of 112 optical and p-ECG recordings (62 at TH, 50 at TH treated with rotigaptide) were analyzed. Adding rotigaptide reduced ventricular divergence, from 0.13±0.10 at TH to 0.09±0.07 (p = 0.018). Similarly, rotigaptide reduced the number of epicardial wavebreaks, from 0.59±0.73 at TH to 0.30±0.49 (p = 0.036). VF inducibility decreased, from 48±31% at TH to 22±32% after rotigaptide infusion (p = 0.032). Linear regression models showed that ventricular divergence correlated with epicardial wavebreaks during TH (p<0.001). CONCLUSION: Ventricular divergence correlated with, and might be predictive of epicardial wavebreaks during PVS at TH. Rotigaptide decreased both the ventricular divergence and epicardial wavebreaks, and reduced the probability of pacing-induced VF during TH
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