Self-compressed inhomogeneous stabilized jellium model and surface relaxation of simple metal thin films

The interlayer spacings near the surface of a crystal are different from that of the bulk. As a result, the value of the ionic density in the normal direction and near to the surface shows some oscillations around the bulk value. To describe this behavior in a simple way, we have formulated the self-compressed inhomogeneous stabilized jellium model and have applied it to simple metal thin films. In this model, for a $\nu$-layered slab, each ionic layer is replaced by a jellium slice of constant density. The equilibrium densities of the slices can be determined by minimizing the total energy per electron of the slab with respect to the slice densities. To avoid the complications that arise due to the number of independent slice-density parameters for large-$\nu$ slabs, we consider a simplified version of the model with three jellium slices: one inner bulk slice with density $\bar n_1$ and two similar surface slices of densities $\bar n_2$. In this simplified model, each slice may contain more than one ionic layer. Application of this model to the $\nu$-layered slabs ($3\le\nu\le 10$) of Al, Na, and Cs shows that, in the equilibrium state, $\bar n_1$ and $\bar n_2$ assume different values, which is significant in the Al case, and the state is more stable than that predicted in the homogeneous model in which only one global jellium density is used for the whole system. In addition, we have calculated the overall relaxations, the work functions, and the surface energies, and compared with the results of the earlier works.Comment: 19 pages, 9 figures, in pdf forma

Self-consistent iterative solution of the exchange-only OEP equations for simple metal clusters in jellium model

In this work, employing the exchange-only orbital-dependent functional, we have obtained the optimized effective potential using the simple iterative method proposed by K\"ummel and Perdew [S. K\"ummel and J. P. Perdew, Phys. Rev. Lett. {\bf 90}, 43004-1 (2003)]. Using this method, we have solved the self-consistent Kohn-Sham equations for closed-shell simple metal clusters of Al, Li, Na, K, and Cs in the context of jellium model. The results are in good agreement with those obtained by the different method of Engel and Vosko [E. Engel and S. H. Vosko, Phys. Rev. B {\bf 50}, 10498 (1994)].Comment: RevTex, 6 pages, 5 eps figures. To appear in Journal of Physics:Condensed Matter (2005

Versatile stochastic dot product circuits based on nonvolatile memories for high performance neurocomputing and neurooptimization.

The key operation in stochastic neural networks, which have become the state-of-the-art approach for solving problems in machine learning, information theory, and statistics, is a stochastic dot-product. While there have been many demonstrations of dot-product circuits and, separately, of stochastic neurons, the efficient hardware implementation combining both functionalities is still missing. Here we report compact, fast, energy-efficient, and scalable stochastic dot-product circuits based on either passively integrated metal-oxide memristors or embedded floating-gate memories. The circuit's high performance is due to mixed-signal implementation, while the efficient stochastic operation is achieved by utilizing circuit's noise, intrinsic and/or extrinsic to the memory cell array. The dynamic scaling of weights, enabled by analog memory devices, allows for efficient realization of different annealing approaches to improve functionality. The proposed approach is experimentally verified for two representative applications, namely by implementing neural network for solving a four-node graph-partitioning problem, and a Boltzmann machine with 10-input and 8-hidden neurons

On including quality in applied automatic gait recognition

Many gait recognition approaches use silhouette data. Imperfections in silhouette extraction have a negative effect on the performance of a gait recognition system. In this paper we extend quality metrics for gait recognition and evaluate new ways of using quality to improve a recognition system. We demonstrate use of quality to improve silhouette data and select gait cycles of best quality. The potential of the new approaches has been demonstrated experimentally on a challenging dataset, showing how recognition capability can be dramatically improved. Our practical study also shows that acquiring samples of adequate quality in arbitrary environments is difficult and that including quality analysis can improve performance markedly

Association of Maternal Working Condition with Low Birth Weight: The Social Determinants of Health Approach

Background: The socioeconomic conditions have made more job opportunities available to women. This has created interest to conduct studies on the effect of working lifestyle on pregnancy outcomes. Aim: This study was conducted with the aim to assess the relationship between mothers’ working status as a social determinant and the incidence of low birth weight (LBW) of the newborn. Subjects and Methods: This case–control study was conducted on 500 women with normal weight infants (control group) and 250 women with LBW infants (case group) in selected hospitals in Tehran. Data were collected using a researcher‑made questionnaire, designed to assess the effect of mothers’ prenatal lifestyle, as a social determinant, on LBW of the newborn. A section of the questionnaire involved assessment of mother’s working condition in terms of the work environment, activities, and job satisfaction. Data were analyzed using Chi‑square and logistic regression tests. Results: LBW among employed mothers was 5 times more likely than unemployed ones (odds ratio = 5.35, P < 0.001). Unfavorable work conditions such as humid environment, contact with detergents, and being in one standing or sitting position for long hours were significantly associated with LBW (P < 0.001). Conclusion: The present study showed that unfavorable work conditions were associated with LBW; therefore, they need special attention.Keywords: Low birth weight, Pregnancy, Socioeconomic factors, Working condition

The relationship of social support and quality of life with the level of stress in pregnant women using the PATH model

Background: Lack of adequate social support, stress, and generally poor quality of life during pregnancy leads to adverse pregnancy outcomes for both the mother and the baby. Objectives: This study aimed to investigate the relationship of social support and quality of life with level of stress during pregnancy. Materials and Methods: This was a descriptive-correlative study conducted on 210 pregnant women (meeting study criteria), attending Shahriar Social Services Hospital during 2012. Purposive convenient sampling was used. Study subjects completed questionnaires of obstetrics and demographics, VAUX social support, World Health Organization quality of life, and stress during pregnancy. Data were analyzed with SPSS-19 and Lisrel 8.8, utilizing statistical path analysis. Results: The final path model fitted well (CF1 = 1, RMSEA = 0.00) and showed that direct quality of life paths with β = -0.2, and indirect social support with β = -0.088 had the most effects on reduction of stress during pregnancy. Conclusion: Social support indirectly and quality of life directly affect stress during pregnancy. Thus, health officials should attempt to establish measures to further enhance social support and quality of life of pregnant women to reduce stress and its consequences during this time. © 2013, Iranian Red Crescent Medical Journal

Mechanical Characterization of Torsional Micropaddles Using Atomic Force Microscopy

The reference cantilever method is shown to act as a direct and simple method for determination of torsional spring constant. It has been applied to the characterization of micropaddle structures similar to those proposed for resonant functionalized chemical sensors and resonant thermal detectors. It is shown that this method can be used as an effective procedure to characterize a key parameter of these devices and would be applicable to characterization of other similar MEMS/NEMS devices such as micromirrors. In this study, two sets of micropaddles are manufactured (beams at centre and offset by 2.5 μm) by using LPCVD silicon nitride as a substrate. The patterning is made by direct milling using focused ion beam. The torsional spring constant is achieved through micromechanical analysis via atomic force microscopy. To obtain the gradient of force curve, the area of the micropaddle is scanned and the behaviour of each pixel is investigated through an automated developed code. The experimental results are in a good agreement with theoretical results

Practical Fss-Based Sensor Sensitivity

Frequency selective surfaces are a periodic array of unit cells that, when illuminated externally, have a specific frequency response that depends on element geometry, spacing, and substrate properties. Theoretically, FSS is assumed as an infinite array of unit cells with a plane wave excitation. However, in practice, an FSS is finite and hence, due to edge effects, the limited number of unit cells, and non-uniform illumination, the response will deviate from the theoretical. As it relates to FSS-based sensing in particular, a localized illumination is often used in order to improve the sensing resolution. However, due to the aforementioned factors, the sensitivity of the sensor may suffer as a result. Hence, the effect of these factors is studied on the FSS sensor response. Then, taking strain measurement as an example, the degradation in the sensor sensitivity to strain is evaluated in comparison with that of a theoretical FSS. The simulation results show that a finite FSS with non-uniform illumination has reduced sensitivity to strain. This degradation in sensitivity of reduces as the number of illuminated unit cells increases. However, the sensitivity of a finite FSS with uniform illumination is nearly constant with respect to the number of illuminated unit cells