Probing dipole-forbidden autoionizing states by isolated attosecond pulses

We propose a general technique to retrieve the information of dipole-forbidden resonances in the autoionizing region. In the simulation, a helium atom is pumped by an isolated attosecond pulse in the extreme ultraviolet (EUV) combined with a few-femtosecond laser pulse. The excited wave packet consists of the $^1S$, $^1P$, and $^1D$ states, including the background continua, near the $2s2p(^1P)$ doubly excited state. The resultant electron spectra with various laser intensities and time delays between the EUV and laser pulses are obtained by a multilevel model and an ab initio time-dependent Schr\"odinger equation calculation. By taking the ab initio calculation as a "virtual measurement", the dipole-forbidden resonances are characterized by the multilevel model. We found that in contrast to the common assumption, the nonresonant coupling between the continua plays a significant role in the time-delayed electron spectra, which shows the correlation effect between photoelectrons before they leave the core. This technique takes the advantages of ultrashort pulses uniquely and would be a timely test for the current attosecond technology.Comment: 10 pages, 6 figure

Resonant enhancement of a single attosecond pulse in a gas medium by a time-delayed control field

An optical coherent control scheme has been proposed and theoretically investigated where an extreme ultraviolet single attosecond pulse (SAP) propagates through a dense helium gas dressed by a time-delayed femtosecond laser pulse. The laser pulse couples the 2s2p(^1P) and 2s^2(^1S) autoionizing states when the SAP excites the 2s2p state. After going through the gas, the spectral and temporal profiles of the SAP are strongly distorted. A narrowed but enhanced spike in the spectrum shows up for specific intensities and time delays of the laser, which exemplifies the control of a broadband photon wave packet by an ultrashort dressing field for the first time. We analyze the photon and electron dynamics and conclude on the dressing condition that maximizes this enhancement. The result demonstrates new possibilities of attosecond optical control.Comment: 5 pages, 4 figure

The Moderating Effect of Familiarity on the Structural Model of Country and Destination Image

This research extends knowledge of how country image influences destination image. Building on Han’s (1989) halo effect model (when consumers are unfamiliar with the product, country image tends to influence product evaluation through product belief) and summary cue model (when consumers are familiar with the product, country image tends to have direct effects on product evaluation), this research examines the moderating effects of familiarity on the structural model of country and destination image. The results indicate that summary cue model is better fitted under both conditions, which highlights the importance of country image as national stereotypes on destination image

Localization and Mobility Gap in Topological Anderson Insulator

It has been proposed that disorder may lead to a new type of topological insulator, called topological Anderson insulator (TAI). Here we examine the physical origin of this phenomenon. We calculate the topological invariants and density of states of disordered model in a super-cell of 2-dimensional HgTe/CdTe quantum well. The topologically non-trivial phase is triggered by a band touching as the disorder strength increases. The TAI is protected by a mobility gap, in contrast to the band gap in conventional quantum spin Hall systems. The mobility gap in the TAI consists of a cluster of non-trivial subgaps separated by almost flat and localized bands.Comment: 8 pages, 7 figure

Effect of non-lattice oxygen on ZrO2-based resistive switching memory

ZrO2-based resistive switching memory has attracted much attention according to its possible application in the next-generation nonvolatile memory. The Al/ZrO2/Pt resistive switching memory with bipolar resistive switching behavior is revealed in this work. The thickness of the ZrO2 film is only 20 nm. The device yield improved by the non-lattice oxygen existing in the ZrO2 film deposited at room temperature is firstly proposed. The stable resistive switching behavior and the long retention time with a large current ratio are also observed. Furthermore, it is demonstrated that the resistive switching mechanism agrees with the formation and rupture of a conductive filament in the ZrO2 film. In addition, the Al/ZrO2/Pt resistive switching memory is also possible for application in flexible electronic equipment because it can be fully fabricated at room temperature

RBC volume deficiency in patients with excessive orthostatic decrease in cerebral blood flow velocity

AbstractBackgroundOrthostatic intolerance (OI) is common but heterogeneous. There is a subgroup of OI patients who have excessive decrease in cerebral blood flow velocity (CBFV) of bilateral middle cerebral arteries (MCAs) during head-up tilt without systemic blood pressure change. This study evaluated the role of blood volume reduction in such patients.MethodsPatients with idiopathic OI who had excessive orthostatic decrease (>20% of the supine level) in mean CBFV of bilateral MCAs and who also received blood volume determination were collected. The chromium (51Cr) dilution method was used for red blood cell (RBC) volume determination in these patients. The blood volume was expressed as a percentage of the expected volume. These patients were further divided into two groups, those with postural tachycardia syndrome (POTS group) and those without (non-POTS group). The data of RBC volume were compared between the two groups. Besides, we used multivariate linear regression to evaluate the factors that predict RBC volume.ResultsTwenty-five patients (13 females, median age = 28 years) were enrolled in this study. Nine of these patients had POTS (5 females, median age = 26 years) and 16 did not (8 females, median age = 29.5 years). Compared with the expected volume, the RBC volume was significantly reduced in all patients (median = 82% of the expected volume). Moreover, the RBC volume was significantly lower in the POTS group than that in the non-POTS group (78% vs. 85% of the expected volume, p = 0.013). The orthostatic decrease of MCA flow velocity was 28.3% in the POTS group and 32.5% in the non-POTS group (p = 0.140). The orthostatic pulsatility index increment was 15.4% in the POTS group and 20.5% in the non-POTS group (p = 0.438). Moreover, basic demography and hemoglobin levels were not different between the two groups. After multivariate linear regression (dependent variables including age, sex, body surface, and groups), only the presence of POTS significantly predicted the RBC volume (p = 0.006).ConclusionThe results of our study indicated that low RBC volume may play an important role in the pathophysiology of OI in this group of patients. Moreover, its role seems even more relevant in patients with POTS than in those without. Further studies for mechanistic evaluation are needed in the future

ANALYZING MEDICAL TRANSACTION DATA BY USING ASSOCIATION RULE MINING WITH MULTIPLE MINIMUM SUPPORTS

The quick development of IS has a huge impact on the healthcare industry. almost all the existing hospitals, clinics and other healthcare-related institutes have adopted a functionally powerful and highly integrated Hospital Information System (HIS) for management of clinic or medical-related affairs. The medical data stored in the HIS are collected from many different medical subsystems, However, problems of failed data sharing and inconsistent data content often occur among these subsystems, resulting in many hospitals collect a large amount of medical data, but not the ability to process and analyse these data properly, letting the valuable data in the HIS all go to waste. In this study, we made a practical visit to a certain hospital in Taiwan and collected radioimmunoassay (RIA) data from the Laboratory Information System (LIS) and the Departmental Registration System (DRS) of this hospital. Further, we proposed a method of the association rule mining in combination with the concept of multiple minimum supports to analyse and find valuable association rules from the RIA data. The analytical results found the method we proposed can indeed find association rules that would not be able to be found with the traditional association mining methods. It is very helpful in improving doctor-patient relationship and upgrading health care quality

Modeling the Relationship among Linguistic Typological Features with Hierarchical Dirichlet Process

PACLIC 23 / City University of Hong Kong / 3-5 December 200