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Abnormal effort-based decision-making represents a potential mechanism underlying motivational deficits (amotivation) in psychotic disorders. Previous research identified effort allocation impairment in chronic schizophrenia and focused mostly on physical effort modality. No study has investigated cognitive effort allocation in first-episode psychosis (FEP).
Cognitive effort allocation was examined in 40 FEP patients and 44 demographically-matched healthy controls, using Cognitive Effort-Discounting (COGED) paradigm which quantified participants’ willingness to expend cognitive effort in terms of explicit, continuous discounting of monetary rewards based on parametrically-varied cognitive demands (levels N of N-back task). Relationship between reward-discounting and amotivation was investigated. Group differences in reward-magnitude and effort-cost sensitivity, and differential associations of these sensitivity indices with amotivation were explored.
Patients displayed significantly greater reward-discounting than controls. In particular, such discounting was most pronounced in patients with high levels of amotivation even when N-back performance and reward base amount were taken into consideration. Moreover, patients exhibited reduced reward-benefit sensitivity and effort-cost sensitivity relative to controls, and that decreased sensitivity to reward-benefit but not effort-cost was correlated with diminished motivation. Reward-discounting and sensitivity indices were generally unrelated to other symptom dimensions, antipsychotic dose and cognitive deficits.
This study provides the first evidence of cognitive effort-based decision-making impairment in FEP, and indicates that decreased effort expenditure is associated with amotivation. Our findings further suggest that abnormal effort allocation and amotivation might primarily be related to blunted reward valuation. Prospective research is required to clarify the utility of effort-based measures in predicting amotivation and functional outcome in FEP.
Better understanding of interplay among symptoms, cognition and functioning in first-episode psychosis (FEP) is crucial to promoting functional recovery. Network analysis is a promising data-driven approach to elucidating complex interactions among psychopathological variables in psychosis, but has not been applied in FEP.
This study employed network analysis to examine inter-relationships among a wide array of variables encompassing psychopathology, premorbid and onset characteristics, cognition, subjective quality-of-life and psychosocial functioning in 323 adult FEP patients in Hong Kong. Graphical Least Absolute Shrinkage and Selection Operator (LASSO) combined with extended Bayesian information criterion (BIC) model selection was used for network construction. Importance of individual nodes in a generated network was quantified by centrality analyses.
Our results showed that amotivation played the most central role and had the strongest associations with other variables in the network, as indexed by node strength. Amotivation and diminished expression displayed differential relationships with other nodes, supporting the validity of two-factor negative symptom structure. Psychosocial functioning was most strongly connected with amotivation and was weakly linked to several other variables. Within cognitive domain, digit span demonstrated the highest centrality and was connected with most of the other cognitive variables. Exploratory analysis revealed no significant gender differences in network structure and global strength.
Our results suggest the pivotal role of amotivation in psychopathology network of FEP and indicate its critical association with psychosocial functioning. Further research is required to verify the clinical significance of diminished motivation on functional outcome in the early course of psychotic illness.
Both double-crystal and triple-axis x-ray diffraction techniques have been used to study complex SiGe/Si structures. A novel method for measuring the nucleation activation energy of dislocations in strain relaxed SiGe/Si structures is presented to illustrate the usefulness of these techniques.
TAOS II is a next-generation occultation survey with the goal of measuring the size distribution of the small end of the Kuiper Belt (objects with diameters 0.5–30 km). Such objects have magnitudes r > 30, and are thus undetectable by direct imaging. The project will operate three telescopes at San Pedro Mártir Observatory in Baja California, México. Each telescope will be equipped with a custom-built camera comprised of a focal-plane array of CMOS imagers. The cameras will be capable of reading out image data from 10,000 stars at a cadence of 20 Hz. The telescopes will monitor the same set of stars simultaneously to search for coincident occultation detections, thus minimising the false-positive rate. This talk described the project, and reported on the progress of the development of the survey infrastructure.
We present a high precision frequency determination method for digitized NMR FID signals. The method employs high precision numerical integration rather than simple summation as in many other techniques. With no independent knowledge of the other parameters of a NMR FID signal (phase ф, amplitude A, and transverse relaxation time T2) this method can determine the signal frequency f0 with a precision of if the observation time T ≫ T2. The method is especially convenient when the detailed shape of the observed FT NMR spectrum is not well defined. When T2 is +∞ and the signal becomes pure sinusoidal, the precision of the method is which is one order more precise than the ±1 count error induced precision of a typical frequency counter. Analysis of this method shows that the integration reduces the noise by bandwidth narrowing as in a lock-in amplifier, and no extra signal filters are needed. For a pure sinusoidal signal we find from numerical simulations that the noise-induced error in this method reaches the Cramer-Rao Lower Band (CRLB) on frequency determination. For the damped sinusoidal case of most interest, the noise-induced error is found to be within a factor of 2 of CRLB when the measurement time T is 2 or 3 times larger than T2. We discuss possible improvements for the precision of this method.
Clarification of memory characteristics of tiny cell is important for practical use of resistive random access memory (ReRAM). However, limitation of semiconductor micro-fabrication technology hinders to obtain memory characteristics in tiny cell with an area comparable to the size of filaments. In this paper, we established a method to prepare a very small memory cell by fabricating ReRAM structure on the tip of a cantilever of atomic force microscope (AFM). We also established a method to avoid the overshoot of set current. As a result, reset current was successfully reduced enough to suppress serious damage to the cantilever. The effective cell size was estimated to be less than 10 nm in diameter due to electric field concentration at the tip of the cantilever, which was confirmed by an electric field simulator based on finite element method. We performed a unique experiment to verify the presence of oxygen pool in an anode, by utilizing removable bottom electrode structure. The result was not consistent with resistive switching models that require the anode to play a role as an oxygen reservoir.
Previous studies have suggested that Lingzhi (Ganoderma lucidum) has antioxidant effects and possibly beneficial effects on blood pressure, plasma lipids and glucose, but these have not been confirmed in subjects with mild hypertension or hyperlipidaemia. The objective of the present study was to assess the cardiovascular, metabolic, antioxidant and immunomodulatory responses to therapy with Lingzhi in patients with borderline elevations of blood pressure and/or cholesterol in a controlled cross-over trial. A total of twenty-six patients received 1·44 g Lingzhi daily or matching placebo for 12 weeks in a randomised, double-blind, cross-over study with placebo-controlled run-in and cross-over periods. Body weight, blood pressure, metabolic parameters, urine catecholamines and cortisol, antioxidant status and lymphocyte subsets were measured after each period. Lingzhi was well tolerated and data from twenty-three evaluable subjects showed no changes in BMI or blood pressure when treated with Lingzhi or placebo. Plasma insulin and homeostasis model assessment-insulin resistance were lower after treatment with Lingzhi than after placebo. TAG decreased and HDL-cholesterol increased with Lingzhi but not with placebo in the first treatment period, but significant carry-over effects prevented complete analysis of these parameters. Urine catecholamines and cortisol, plasma antioxidant status and blood lymphocyte subsets showed no significant differences across treatments. Results indicate that Lingzhi might have mild antidiabetic effects and potentially improve the dyslipidaemia of diabetes, as shown previously in some animal studies. Further studies are desirable in patients with hyperglycaemia.
Background: The Consortium to Establish a Registry for Alzheimer's Disease Neuropsychological Assessment Battery (CERAD-NAB) offers information on the clinical diagnosis of Alzheimer's disease (AD) and gives a profile of cognitive functioning. This study explores the effects of age, education and gender on participants' performance on eight subtests in the Chinese-Cantonese version of the CERAD-NAB.
Methods: The original English version of the CERAD-NAB was translated and content-validated into a Chinese-Cantonese version to suit the Hong Kong Chinese population. The battery was administered to 187 healthy volunteers aged 60 to 94 years. Participants were excluded if they had neurological, medical or psychiatric disorders (including dementia). Stepwise multiple linear regression analyses were performed to assess the relative contribution of the demographic variables to the scores on each subtest.
Results: The Cantonese version of CERAD-NAB was shown to have good content validity and excellent inter-rater reliability. Stepwise multiple regression analyses revealed that performances on seven and four out of eight subtests in the CERAD-NAB were significantly influenced by education level and age, respectively. Age and education had significant effects on participants' performance on many tests. Gender also showed a significant effect on one subtest.
Conclusions: The preliminary data will serve as an initial phase for clinical interpretation of the CERAD-NAB for Cantonese-speaking Chinese elders.
A number of F2-based plasma chemistries (NF3, SF6, PF5 and BF3) were investigated for high rate etching of SiC. The most advantageous of these is SF6, based on the high rate (0.6 μm · min−1) it achieves and its relatively low cost compared to NF3. The changes in electrical properties of the near-surface region are relatively minor when the incident ion energy is kept below approximately 75 eV. At a process pressure of 5 mTorr, the SiC etch rate falls-off by ∼15 % in 30 μm diameter via holes compared to larger diameter holes (> 60 μm diameter) or open areas on the mask.
The cathodic kinetic processes on a highly oriented LSCO thin film electrode supported on YSZ(100) surface were studied with a 3-probe ac impedance method under varying bias potential and annealing temperatures. Three distinctive features observed in the impedance spectra were assigned to contributions from the ionic conduction of the YSZ electrolyte, the ionic transfer at the LSCO/YSZ interface, and the oxygen exchange on the LSCO electrode surface. The changes of the three features with respect to the annealing history and bias potential were measured. The impedance data were analyzed using an equivalent circuit model: (RelCel)(RinterfaceQinterface)(RsurfCsurf).
The strain relaxation and threading dislocation density of He-implanted and annealed SiGe/Si heterostructures have been studied. For He doses above a threshold of 8×1015 cm−2, the degree of strain relaxation depends primarily on the SiGe layer thickness; a similar degree of strain relaxation is obtained when the He dose and energy are varied over a relatively wide range. In contrast, the threading dislocation density is strongly influenced by the implantation depth. There is a strong correlation between the parameter He(SiGe), the He dose in the SiGe layer calculated from He profiles simulated using the program Stopping and Range of Ions in Matter (SRIM), and the threading dislocation density. We find that to achieve a low threading dislocation density, <5×107 cm−2, He(SiGe) must be less than 1015 cm−2. The strain relaxation mechanism is also discussed.
The development of a self-aligned fabrication process for small emitter contact area (2×4 um2) GaN/AlGaN heterojunction bipolar transistors and GaN bipolar junction transistors is described. The process features dielectric-spacer sidewalls, low damage dry etching and selected-area regrowth of p-GaAs(C) on the base contact or n-GaN/AlGaN on the emitter contact. Series resistance effects are still found to influence the device performance.
Phase assemblages in two Sr-Bi-Pb-Ca-Cu-O glasses and their crystallization into glass-ceramics through a sequence of heat treatments are described. Samples were heat treated at various temperatures based on differential thermal analysis (DTA) analysis of the as-quenched glasses. X-ray powder diffraction was used to identify the compounds in each sample; and the different phases formed in these two samples were compared. Results of microstructural characterization of selected samples using scanning electron microscopy are discussed.
Pulsed KrF (248 nm) laser ablation has been used for in situ growth of smooth, high‐quality YBa2Cu3O7‐x epitaxial films of variable thickness on SrTiO3, KTaO3, LaGaO3, LaA1O3, cubic ZrO2, and MgO substrates, at temperatures of ∼60O‐730°C, without higher temperature post‐annealing. A rotating target pellet, fine focusing by a single cylindrical lens, laser‐beam scanning over the target, and laser energy densities ∼2.5‐3 J/cm2 can be combined to yield films of completely uniform composition and with ∼25% thickness variation over areas ∼8 cm2. The best films have Tc > 92 K and JC(H = 0, T = 77 K) > 2 MA/cm2. Film‐growth procedures are described, together with results of superconducting and normal‐state transport measurements.
We have measured the infrared (IR) reflectance and Raman spectra of electron doped and undoped Nd2CuO4 and Pr2CuO4. Utilizing the results from doped ceramics and undoped ab plane oriented single crystals, we observe and assign all the IR active phonons (3A2u + 4Eu) predicted by group theory. We have also observed the Raman active modes involving atom motion along the c axis. We compare our results to those found in the related hole superconductors based upon La2CuO4.
We report in‐situ fabrication of c‐axis textured YBa2Cu3O7‐x superconducting thin films with Tco > 77K on unbuffered silicon substrates by the biased pulsed laser evaporation (PLE) technique in the temperature range of 550‐650°C. At substrate temperatures below 550°C, no c‐axis texturing of the superconducting film was observed. The YBa2Cu3O7‐x superconducting films were fabricated by ablating a bulk YBa2Cu3O7 target by a XeCl excimer laser (λ = 308 nm, τ = 45 × 10‐9 sec) in a chamber maintained at an oxygen pressure of 0.2 torr . The thickness of the films was varied from 0.3 to 0.5 nm depending on the number of laser pulses. Extensive diffusion was observed in thin films deposited at substrate temperatures above 550°C. However, microstructurally, with increase in the substrate temperature the films exhibited larger grain size and greater degree of c‐axis texturing (measured by the ratio of the (005) and (110) X‐ray diffraction peaks). This was found to give rise to better superconducting properties with Tco exceeding 77 K for YBa2Cu3O7‐x films deposited on Si substrates at 650°C.
K(Ta,Nb)O3 (KTN) is an interesting substrate for use in studies of epitaxial superconducting film‐substrate interactions because of a moderate lattice parameter mismatch with YBa2Cu3O7‐x and great versatility in electrical properties. KTN's properties are easily modified by doping to form an n‐type semiconductor and/or a ferroelectric with variable ferroelectric Tp. As an initial step in exploring such studies we have carried out what are believed to be the first epitaxial growth experiments of YBa2Cu3O7‐x films on insulating, semiconducting and ferroelectric KTN single crystals by pulsed laser ablation. We find that c‐axis‐normal epitaxial films can be consistently grown with TSc(R = 0) > 90K , △TSC ~1.5K, and Jc > IMA/cm2 on semiconducting and/or insulating KTaO3. However, growth on KNDO3 is problematic because of stresses generated by cooling the substrate through first order structural transitions, at even moderate cooling rates.
Results are presented for 850°C oxygen annealing experiments (up to 62 hr) on the 2122 (Tl:Ca:Ba:Cu) oxide phase, with and without intermediate grinding. Samples were characterized by powder X-ray diffraction and a.c. magnetic susceptibility. The 2122 phase appears to be thermodynamically stable in oxygen under conditions of both extensive grinding, and, annealing of long duration. However, onset Tc's vary from 71 K to 109 K for apparently single-phase 2122 samples with nearly identical X-ray powder patterns, depending upon the heat treatment.
The microstructure of Y-Ba-Cu-O compound, sintered at 950°C for 16h, was examined by using transmission electron microscope(TEM). For the furnace cooling sample, two variants of–orthorhombic YBa2-Cu3O7−x (O-Y123) twins, grown on (110) and (110) planes, respectively, are crystallographically related to the matrix and produce a Widmanstatten morphology. The orientation relationship between the lath twin and the matrix is (001)T//(001) and T//M. The O-Y123 compound is unstable under tne electron irradition. Twin boundaries are identified as S-boundaries. The minor phases as Y2BaCuO5 (Y211) and BaCuO2 were also observed. For the air cooling sample, no superconductivity above 77K was found. The major phase is tetragonal Y123 (T-Y123), while small amount of 0-Y123 is also existent.