Monte Carlo transient phonons transport in silicon and germanium at nanoscales

Heat transport at nanoscales in semiconductors is investigated with a statistical method. The Boltzmann Transport Equation (BTE) which characterize phonons motion and interaction within the crystal lattice has been simulated with a Monte Carlo technique. Our model takes into account media frequency properties through the dispersion curves for longitudinal and transverse acoustic branches. The BTE collisional term involving phonons scattering processes is simulated with the Relaxation Times Approximation theory. A new distribution function accounting for the collisional processes has been developed in order to respect energy conservation during phonons scattering events. This non deterministic approach provides satisfactory results in what concerns phonons transport in both ballistic and diffusion regimes. The simulation code has been tested with silicon and germanium thin films; temperature propagation within samples is presented and compared to analytical solutions (in the diffusion regime). The two materials bulk thermal conductivity is retrieved for temperature ranging between 100 K and 500 K. Heat transfer within a plane wall with a large thermal gradient (250 K-500 K) is proposed in order to expose the model ability to simulate conductivity thermal dependence on heat exchange at nanoscales. Finally, size effects and validity of heat conduction law are investigated for several slab thicknesses

Direct Measurement of Pyroelectric and Electrocaloric Effects in Thin Films

An understanding of polarization-heat interactions in pyroelectric and electrocaloric thin-film materials requires that the electrothermal response is reliably characterized. While most work, particularly in electrocalorics, has relied on indirect measurement protocols, here we report a direct technique for measuring both pyroelectric and electrocaloric effects in epitaxial ferroelectric thin films. We demonstrate an electrothermal test platform where localized high-frequency (approximately 1 kHz) periodic heating and highly sensitive thin-film resistance thermometry allow the direct measurement of pyrocurrents (<10 pA) and electrocaloric temperature changes (<2 mK) using the “2-omega” and an adapted “3-omega” technique, respectively. Frequency-domain, phase-sensitive detection permits the extraction of the pyrocurrent from the total current, which is often convoluted by thermally-stimulated currents. The wide-frequency-range measurements employed in this study further show the effect of secondary contributions to pyroelectricity due to the mechanical constraints of the substrate. Similarly, measurement of the electrocaloric effect on the same device in the frequency domain (at approximately 100 kHz) allows for the decoupling of Joule heating from the electrocaloric effect. Using one-dimensional, analytical heat-transport models, the transient temperature profile of the heterostructure is characterized to extract pyroelectric and electrocaloric coefficients

Vertical cavity surface emitting laser based optoelectronic asynchronous transfer mode switch

Abstract. Large broadband asynchronous transfer mode (ATM) switching nodes require novel hardware solutions that could benefit from the inclusion of optical interconnect technology, since electronic solutions are limited by pin out and by the capacitance/inductance of the interconnections. We propose, analyze and demonstrate a new three stage free space optical switch that utilizes vertical cavity surface emitting lasers (VCSELs) for the optical interconnections, a liquid crystal spatial light modulator (SLM) as a reconfigurable shutter and relatively simple optics for fan out and fan in. A custom complementary metal oxide semiconductor (CMOS) chip is required to introduce a time delay in the optical bit stream and to drive the VCSELs. Analysis shows that the switch should be scalable to 1024ϫ1024, which would require 2048 ϳ2 mW VCSELs

Experiences of support garments following bowel stoma formation: analysis of free-text responses in a cross-sectional survey

Aim: To explore the experiences of support garments when adjusting to bodily change following bowel stoma formation. Design: Thematic analyses of free-text responses in a cross-sectional survey of the stoma population in 2018. Methods: Free-text responses were invited so that respondents could describe their experiences in more detail. A process of induction was chosen to allow for themes to emerge directly from the data. The concept ‘embodiment’ was used as a theoretical framework during interpretation. Results: 1425 people with a bowel stoma responded to the survey, of whom 598 provided free-text responses. Four themes about experiences of support garments in the context of changed bodily experiences following stoma formation were identified: body complications, which is about experiences of using support garments to prevent or self-manage parastomal hernia; body appearance, which is about hiding the stoma and stoma appliance; body function, which is about managing stoma appliance complications; and body sensation, which is mainly about negative experiences of ill-fitting garments. Conclusion: Support garments can be understood as items that are used by people during an ongoing process of adjusting to bodily changes following stoma formation and as part of an ongoing process of reconstructing new embodied selves. Impact: This is the first study to explore people’s experiences of support garments following bowel stoma formation. Support garments are used in the self-management of body complications, appearance, function and sensations. Stoma nurses may draw on the findings of this study to advise patients about the benefits of garments for adjusting to bodily change, and garment suppliers should address people’s negative experiences by improving garments

High-Risk Cervical Human Papillomavirus Infections among Human Immunodeficiency Virus-Positive Women in the Bahamas

Background\ud \ud High-risk (HR) HPV genotypes other than 16 and 18 have been detected in a significant proportion of immunocompromised females. We aim to evaluate the frequency of HR HPV genotypes in a population of HIV-positive Caribbean women.\ud Methods\ud \ud One hundred sixty-seven consecutive, non-pregnant, HIV-positive females ≥18 years were recruited in this study. Each participant received a vaginal examination, PAP smear, and completed a questionnaire. DNA was extracted for HPV testing in 86 patients.\ud Results\ud \ud Mean age was 39.1 years for women positive for HR HPV and 43.1 years for women negative for HR HPV (P value = 0.040). 78% (130/167) of the women had HR HPV infections; the prevalence of abnormal cervical cytology was 38% among women who were HR HPV-positive compared to women who were HR HPV-negative (22%). Fifty-one percent of the 86 women with available genotype carried infections with HPV 16 and/or HPV 18; genotypes of unknown risk were also frequently observed. Women who had a CD4+ count of ≤200 had 7 times increased odds of carrying HR HPV infection in comparison to women with CD4+>200.\ud Conclusions\ud \ud HR HPV infections in HIV infected females may consist of more than just HPV 16 and 18, but also HPV 52 and 58. Further studies are needed to determine whether HPV 52 and 58 play a significant role in the development of cervical cytological abnormalities in HIV+ women

Pemberdayaan Masyarakat dalam Pembuatan Sabun Padat dari Daun Sirih (Piper betle L.)

Covid-19 is an infection channel in human respiratory caused by coronavirus, which spread all over the world in 2020, thus implementing lockdown to lower the spread of the corona virus. Because Covid-19 communities have a reduced income especially in birds watching Isyo Hills in Nimbokrang especially in Muaif Village, and in Rhepang village it has a rich diversity of life, including betle leaves, where betle leaves have many benefits and properties such as betlephenol, saponin, sesterypen, starch, kovikol, where a natural antiseptic agent is available, The purpose of this activities is to make a solid soap of betel leaves (Piper betle L.) as antibacterias, and to support the economic growth of people in reple-betel leaves  is 10%, and the cost of rhi-leaf extract is 15 g, the respondents of society are 82% approved, 18% agree once in "a compact soap tutorial of the betel leaf," and 73%, 45%, and 64% in turn favor to smell, shape, and the color of the soap. Then, according to 73% of participants feel the tools and materials used in the manufacture of soap. And finally, the number of attendees who filled the questionnaire's list was attracted to making solid soap after a solid soapmaking tutorial.Keyword: antibacteria; betel leaves; Covid-19; Rhepang Muaif villages; solid soa