Lattice Heat Capacity of Mesoscopic Nanostructures

We present a rigorous full quantum mechanical model for the lattice heat capacity of mesoscopic nanostructures in various dimensions. Model can be applied to arbitrary nanostructures with known vibrational spectrum in zero, one, two, or three dimensions. The limiting case of infinitely sized multi-dimensional materials are also found, which are in agreement with well-known results. As examples, we obtain the heat capacity of fullerenes

Meta-analysis of School Climate and Well-Being of LGBTQ Youth: A Case Study of Alabama’s Public School Climate Toward Sexual Minority Students

Decades of research demonstrates that adolescents who identify as lesbian, gay, bisexual, transgender, or questioning (LGBTQ), are at higher risk of peer victimization, harassment, and bullying compared to heterosexual youth. It is reported that 3 out of every 4 LGBTQ students are verbally harassed and 1 out of every 3 is physically bullied (Kosciw et al., 2014). Exposure to constant victimization, harassment, and bullying can subsequently pave the way to a host of negative psychological and educational outcomes. The current research is a systematic review and a meta-analysis of school climate and its impact on the LGBTQ students. This research investigates whether the disparity in rates of victimization, harassment, and bullying in school can explain adverse psychological and educational outcomes experienced by sexual minority youth. The study also demonstrates the buffering influence of a positive and supportive school climate. In addition, a case study of the policies and practices of Alabama public schools is conducted to evaluate the state’s responsiveness towards the needs of the LGBTQ students. Results suggest that sexual minority youth are at an increased risk of victimization, harassment, and bullying. Further, these experiences contribute to a host of adverse psychological and educational outcomes. Moreover, the present study demonstrates that positive and supportive school climate plays a protective role in buffering the negative outcomes experienced by the sexual minority student

The New Era of Doing Business with Iran: Iran’s International Commercial Transactions and Global Security

On January 17, 2016, in a statement following his signing of the Joint Comprehensive Plan of Action (JCPOA) with Iran, President Obama addressed that country’s people, stating that “yours is a great civilization, with a vibrant culture that has so much to contribute to the world – in commerce, and in science and the arts.” While the former U.S. President’s evaluation of the Iranian people’s greatness is indisputable, there are questions concerning doing business with Iran which transcend conventional legal issues and commercial problems. Given the juxtaposition of Iran’s duopolistic government structure and ideologically oriented decision-making processes, questions arise as to what extent multinational corporations, including U.S. companies, should reasonably expect to conduct commercial transactions with that country. Specific issues arise related to Iranian banks, international credit recognition, terms of payment, and the conceptual legality of interest in Iran. In addition, more practical issues arise related to the governing law of contract and proper dispute resolution mechanisms. Furthermore, U.S. regulatory constraints limit the efficacy of certain contracts between Iran and U.S. companies. This article attempts to illustrate the structural, legal and operational issues concerning doing business with Iran and, where possible, means for mitigating such issues

Roll convection of binary fluid mixtures in porous media

We investigate theoretically the nonlinear state of ideal straight rolls in the Rayleigh-B\'enard system of a fluid layer heated from below with a porous medium using a Galerkin method. Applying the Oberbeck-Boussinesq approximation, binary mixtures with positive separation ratio are studied and compared to one-component fluids. Our results for the structural properties of roll convection resemble qualitatively the situation in the Rayleigh--B\'enard system without porous medium except for the fact that the streamlines of binary mixtures are deformed in the so-called Soret regime. The deformation of the streamlines is explained by means of the Darcy equation which is used to describe the transport of momentum. In addition to the properties of the rolls, their stability against arbitrary infinitesimal perturbations is investigated. We compute stability balloons for the pure fluid case as well as for a wide parameter range of Lewis numbers and separation ratios which are typical for binary gas and fluid mixtures. The stability regions of rolls are found to be restricted by a crossroll, a zigzag and a new type of oscillatory instability mechanism, which can be related to the crossroll mechanism

A Thermal and Electrical Analysis of Power Semiconductor Devices

The state-of-art power semiconductor devices require a thorough understanding of the thermal behavior for these devices. Traditional thermal analysis have (1) failed to account for the thermo-electrical interaction which is significant for power semiconductor devices operating at high temperature, and (2) failed to account for the thermal interactions among all the levels involved in, from the entire device to the gate micro-structure. Furthermore there is a lack of quantitative studies of the thermal breakdown phenomenon which is one of the major failure mechanisms for power electronics. This research work is directed towards addressing. Using a coupled thermal and electrical simulation, in which the drift-diffusion equations for the semiconductor and the energy equation for temperature are solved simultaneously, the thermo-electrical interactions at the micron scale of various junction structures are thoroughly investigated. The optimization of gate structure designs and doping designs is then addressed. An iterative numerical procedure which incorporates the thermal analysis at the device, chip and junction levels of the power device is proposed for the first time and utilized in a BJT power semiconductor device. In this procedure, interactions of different levels are fully considered. The thermal stability issue is studied both analytically and numerically in this research work in order to understand the mechanism for thermal breakdown

Stokes flow past a two-layers heterogeneous porous sphere with the effect of stress jump condition: An exact solution

The flow past a porous sphere has extensive industrial and engineering applications, such as the flow of pulverized coals particulate during combustion, sedimentation of fine particulate suspensions, flow in porous beds etc. Several studies have been done about the flow past a porous body under different models and boundary conditions. The models used in their investigations can be divided into the following categories: (i) Adopting Darcy equation to describe the flow in porous media and Stokes equations to describe the flow in the free fluid with the continuity conditions of velocity and pressure at the interface or the Beavers-Joseph (BJ) interface conditions; (ii) Adopting the Darcy-Brinkman equation to describe the flow inside the porous region and Stokes equations to describe the flow in the free fluid region with interface conditions which are the continuity of velocity components and stresses at the interface or with the Ochoa-Tapia and Whitaker interface conditions, in which shearing stress jump at the interface is considered. However, most of researches just considered one-layer porous medium whether it was a porous sphere or a porous sphere containing a solid concentric spherical core or a concentric spherical cavity. P. D. Verma and B. S. Bhatt (1976) investigated the flow past a heterogeneous porous sphere with the Darcy model. Please download the full abstract below

Peristaltic Transport of a Jeffrey Fluid with Variable Viscosity through a Porous Medium in an Asymmetric Channel

The peristaltic flow of a Jeffrey fluid with variable viscosity through a porous medium in an asymmetric channel is investigated. The channel asymmetric is produced by choosing the peristaltic wave train on the wall of different amplitude and phase. The governing nonlinear partial differential equations for the Jeffrey fluid model are derived in Cartesian coordinates system. Analytic solutions for stream function, velocity, pressure gradient, and pressure rise are first developed by regular perturbation method, and then the role of pertinent parameters is illustrated graphically

The Effect of Depression on Women's Contraceptive Behaviors and Teenage Pregnancy

Objective: The overall objective of this dissertation was to investigate the effect of depression on women’s contraceptive behaviors and teenage pregnancy. Methods: In the first study, the relationship between pre-abortion depressive symptoms and effectiveness level of contraceptive method chosen (low, moderately, or highly effective) after contraceptive counseling was examined using multinomial logistic regression in a group of women seeking abortion services. In the second study Cox proportional hazards models were used to estimate the hazard of contraceptive method discontinuation and unintended pregnancy among women experiencing any current and past elevated depressive symptoms in reproductive health settings. The third study examined the association between first depressive episode relative to age at first sex, and the hazard of first teenage pregnancy among girls participating in the National Comorbidity Survey–Adolescent Supplement. Results: More pre-abortion depressive symptoms were associated with higher odds of choosing a low contraceptive method than a moderately or a highly effective contraceptive method. Compared to non-depressed women, women exposed to baseline and a history of elevated depressive symptoms and those exposed to a history of elevated depressive symptoms had 39% and 12% increased hazards of contraceptive method discontinuation respectively; though the associations were not statistically significant when examining all contraceptive methods together. These associations were significant among patch and the injectable users. Finally, adolescent girls whose first depressive episode occurred at the same age as their sexual debut had a higher likelihood of experiencing first teenage pregnancy (HR: 2.73, 95% CI 1.07, 6.97) than those experiencing no depression onset. Conclusion: This dissertation provides evidence for the critical role of timing of depression in determining women’s contraceptive behaviors and reproductive decisions. The findings collectively suggest that not only the presence or absence of depression, but also the time the condition manifests itself during the course of women’s live can predict women’s decisions surrounding contraceptive method choice, continuation, and pregnancy. Implications: The integration of mental and reproductive health as well as a more effective patient-physician communication are warranted in an effort to optimize pregnancy outcomes in women at risk for depression

Modified artificial diet for rearing of tobacco budworm, Helicoverpa armigera using the Taguchi method and Derringer’s desirability function

With the aim to improve the mass rearing feasibility of tobacco budworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae), design of experimental methodology using Taguchi orthogonal array was applied. To do so, the effect of 16 ingredients of an artificial diet including bean, wheat germ powder, Nipagin, ascorbic acid, formaldehyde, oil, agar, distilled water, ascorbate, yeast, chloramphenicol, benomyl, penicillin, temperature, humidity, and container size on some biological characteristics of H. armigera was evaluated. The selected 16 factors were considered at two levels (32 experiments) in the experimental design. Among the selected factors, penicillin, container size, formaldehyde, chloramphenicol, wheat germ powder, and agar showed significant effect on the mass rearing performance. Derringer's desirability function was used for simultaneous optimization of mass rearing of tobacco budworm, H. armigera, on a modified artificial diet. Derived optimum operating conditions obtained by Derringer's desirability function and Taguchi methodology decreased larval period from 19 to 15.5 days (18.42 % improvement), decreased the pupal period from 12.29 to 11 days (10.49 % improvement), increased the longevity of adults from 14.51 to 21 days (44.72 % improvement), increased the number of eggs/female from 211.21 to 260, and increased egg hatchability from 54.2% to 72% (32.84 % improvement). The proposed method facilitated a systematic mathematical approach with a few well-defined experimental sets