Coupling of Length Scales and Atomistic Simulation of MEMS Resonators

We present simulations of the dynamic and temperature dependent behavior of Micro-Electro-Mechanical Systems (MEMS) by utilizing recently developed parallel codes which enable a coupling of length scales. The novel techniques used in this simulation accurately model the behavior of the mechanical components of MEMS down to the atomic scale. We study the vibrational behavior of one class of MEMS devices: micron-scale resonators made of silicon and quartz. The algorithmic and computational avenue applied here represents a significant departure from the usual finite element approach based on continuum elastic theory. The approach is to use an atomistic simulation in regions of significantly anharmonic forces and large surface area to volume ratios or where internal friction due to defects is anticipated. Peripheral regions of MEMS which are well-described by continuum elastic theory are simulated using finite elements for efficiency. Thus, in central regions of the device, the motion of millions of individual atoms is simulated, while the relatively large peripheral regions are modeled with finite elements. The two techniques run concurrently and mesh seamlessly, passing information back and forth. This coupling of length scales gives a natural domain decomposition, so that the code runs on multiprocessor workstations and supercomputers. We present novel simulations of the vibrational behavior of micron-scale silicon and quartz oscillators. Our results are contrasted with the predictions of continuum elastic theory as a function of size, and the failure of the continuum techniques is clear in the limit of small sizes. We also extract the Q value for the resonators and study the corresponding dissipative processes.Comment: 10 pages, 10 figures, to be published in the proceedings of DTM '99; LaTeX with spie.sty, bibtex with spiebib.bst and psfi

Supporting trans employees in the workplace

The research aimed to provide greater insight into managing gender identity at work and its implications for UK workplaces. In particular, it aimed to provide relevant insights for managers and employees using primary research evidence

Pik3r1 Is Required for Glucocorticoid-Induced Perilipin 1 Phosphorylation in Lipid Droplet for Adipocyte Lipolysis.

Glucocorticoids promote lipolysis in white adipose tissue (WAT) to adapt to energy demands under stress, whereas superfluous lipolysis causes metabolic disorders, including dyslipidemia and hepatic steatosis. Glucocorticoid-induced lipolysis requires the phosphorylation of cytosolic hormone-sensitive lipase (HSL) and perilipin 1 (Plin1) in the lipid droplet by protein kinase A (PKA). We previously identified Pik3r1 (also called p85α) as a glucocorticoid receptor target gene. Here, we found that glucocorticoids increased HSL phosphorylation, but not Plin1 phosphorylation, in adipose tissue-specific Pik3r1-null (AKO) mice. Furthermore, in lipid droplets, the phosphorylation of HSL and Plin1 and the levels of catalytic and regulatory subunits of PKA were increased by glucocorticoids in wild-type mice. However, these effects were attenuated in AKO mice. In agreement with reduced WAT lipolysis, glucocorticoid- initiated hepatic steatosis and hypertriglyceridemia were improved in AKO mice. Our data demonstrated a novel role of Pik3r1 that was independent of the regulatory function of phosphoinositide 3-kinase in mediating the metabolic action of glucocorticoids. Thus, the inhibition of Pik3r1 in adipocytes could alleviate lipid disorders caused by excess glucocorticoid exposure

Suspending Lefschetz fibrations, with an application to Local Mirror Symmetry

We consider the suspension operation on Lefschetz fibrations, which takes p(x) to p(x)-y^2. This leaves the Fukaya category of the fibration invariant, and changes the category of the fibre (or more precisely, the subcategory consisting of a basis of vanishing cycles) in a specific way. As an application, we prove part of Homological Mirror Symmetry for the total spaces of canonical bundles over toric del Pezzo surfaces.Comment: v2: slightly expanded expositio

DOF phase separation of the Lennard-Jones fcc(111) surface

Recent lattice model calculations have suggested that a full-layered crystal surface may undergo, under canonical (particle-conserving) conditions, a preroughening-driven two-dimensional phase separation into two disordered flat (DOF) regions, of opposite order parameter. We have carried out extensive classical molecular dynamics (MD) simulations of the Lennard-Jones fcc(111) surface, to check whether these predictions are relevant or not for a realistic continuous system. Very long simulation times, a grid of temperatures from (2/3)Tm to Tm, and unusually large system sizes are employed to ensure full equilibrium and good statistics. By examining layer-by-layer occupancies, height fluctuations, sublattice order parameter and X-ray structure factors, we find a clear anomaly at ~0.83Tm. The anomaly is distinct from roughening (whose incipiency is also detected at ~0.94Tm), and is seen to be consistent with the preroughening plus phase separation scenario.Comment: REVTeX, 8 pages, 4 figures; new figure showing simulation snapshots added; reference updated and other minor change

The Economics of Battery Storage for Residential Solar Customers in Southern California

Battery storage coupled with solar panels became a consideration after the original net metering program in California (NEM 1.0) ended and gave way to the current net metering program (NEM 2.0). Under NEM 2.0, battery storage gives customers under time-of-use (TOU) rate plans the ability to store the excess electrical energy generated by their panels during sunlight hours (when electricity usage and resale rates are low) and then use that energy in the evening when rates are significantly higher. This reduces the amount of expensive electricity that the customer would have to purchase from the grid. It is widely expected that the current net metering program in California will be replaced by a more restrictive and much less financially attractive program when NEM 3.0 goes into effect in early 2022. The impending introduction of NEM 3.0 has accelerated the rate at which homeowners are installing solar panel arrays and battery storage. In this paper we examine the economics of installing battery storage for residential customers and examine whether battery storage makes financial sense. We use public data to model the electricity bills for an average sized residential customer in southern California and examine how much money this customer can save using battery storage under the current rate plans

The Economics of Residential Solar Panels: A Comparison of Energy Charges for Different Load Profiles, Rate Plans, and Panel Orientations

This paper examines the effect of different residential electrical load profiles (electrical energy consumption patterns within a day) on energy charges for customers with solar panels under different Southern California Edison time-of-use (TOU) rate plans. We identify the TOU plan which would be the most cost effective for solar customers with each load profile. The impact of the orientation of the solar panel array (whether it faces south or west or east) and shading patterns on electricity charges are examined. We also determine the ideal usage offset (the percentage of electricity consumption provided by the solar array) for the various scenarios presented in this paper. We perform these analyses using actual data for the average sized residential customer of Southern California Edison. While the data we examine are based on solar panel production estimates for southern California, the issues we address, and the methods we use, are applicable to virtually any locality. And our analysis reveals how myriad factors impact the economics of residential solar panel systems regardless of location

A study of the conditions governing the formation and germination of spores of Clostridium perfringens type A

Abstract Not Provided

Ipratropium bromide delivered by metered-dose aerosol to infant wheezers

Two methods of administration of ipratropium bromide (Atrovent; Boehringer Ingelheim) to wheezing children'< 25 months of age were compared: (i) the conventional nebulisation (15 children); and (ii) a metered-dose aerosol plus spacer and mask (MDA group, 17 children). The drug induced a significant and similar fall in respiratory rate in both groups. Transcutaneous carbon dioxide pressure was also reduced significantly but was more marked in the MDA group. This increase in alveolar ventilation was 'similar in those < 12 months as in older children; in those with recurrent or with first time wheezing; and in those with radiological evidence of pneumonia. Clinical assessment of bronchospasm and recession was recorded as improved' in over 80% of both groups. The MDA delivery of ipratropium bromide was as effective as nebulisation and was more convenient, since it required less time and equipment. It was also well accepted by the small patients