Dynamics of a nanowire superlattice in an ac electric field

With a one-band envelope function theory, we investigate the dynamics of a finite nanowire superlattice driven by an ac electric field by solving numerically the time-dependent Schroedinger equation. We find that for an ac electric field resonant with two energy levels located in two different minibands, the coherent dynamics in nanowire superlattices is much more complex as compared to the standard two-level description. Depending on the energy levels involved in the transitions, the coherent oscillations exhibit different patterns. A signature of barrier-well inversion phenomenon in nanowire superlattices is also obtained.Comment: 14 pages, 4 figure

Design of Subsurface Geodrain for Automated Industrial Unit – Case Study

This paper describes the pre-construction modeling for design and post-construction evaluation of subsurface drainage systems for an industrial plant. Rajshree Polyfil Ltd has a polyester filament manufacturing plant spread over 50 hectare area in Bharuch district of Gujarat State, India. The plant is fully automatic and robotics operated. The cable duct for control system was laid below formation level. The seepage water was observed in the cable trench and nearby vicinity. This seriously affects the functioning of computer controlled production system. Preliminary investigation revealed that the ground water level was around 1.0m depth below formation level, which was more than 15m depth during the construction of unit. Detailed subsurface investigations and field permeability tests are carried out. Subsurface drainage system was designed and its performance was estimated prior to construction of drain with the help of computer modeling using software MODFLOW. The model area was divided in three to five layers having different permeability values obtained from field test. After construction of subsurface geodrain, discharge was measured and water level was also measured at few piezometers installed near the drain. It is found that the performance of the drain is well in accordance with the design

Dietary elimination of children with food protein induced gastrointestinal allergy – micronutrient adequacy with and without a hypoallergenic formula?

Background: The cornerstone for management of Food protein-induced gastrointestinal allergy (FPGIA) is dietary exclusion; however the micronutrient intake of this population has been poorly studied. We set out to determine the dietary intake of children on an elimination diet for this food allergy and hypothesised that the type of elimination diet and the presence of a hypoallergenic formula (HF) significantly impacts on micronutrient intake. Method: A prospective observational study was conducted on children diagnosed with FPIGA on an exclusion diet who completed a 3 day semi-quantitative food diary 4 weeks after commencing the diet. Nutritional intake where HF was used was compared to those without HF, with or without a vitamin and mineral supplement (VMS). Results: One-hundred-and-five food diaries were included in the data analysis: 70 boys (66.7%) with median age of 21.8 months [IQR: 10 - 67.7]. Fifty-three children (50.5%) consumed a HF and the volume of consumption was correlated to micronutrient intake. Significantly (p <0.05) more children reached their micronutrient requirements if a HF was consumed. In those without a HF, some continued not to achieve requirements in particular for vitamin D and zinc, in spite of VMS. Conclusion: This study points towards the important micronutrient contribution of a HF in children with FPIGA. Children, who are not on a HF and without a VMS, are at increased risk of low intakes in particular vitamin D and zinc. Further studies need to be performed, to assess whether dietary intake translates into actual biological deficiencies

Development of a three-dimensional time-dependent flow field model

A three-dimensional, time-dependent mathematical model to represent Mobile Bay was developed. Computer programs were developed which numerically solve the appropriate conservation equations for predicting bay and estuary flow fields. The model is useful for analyzing the dispersion of sea water into fresh water and the transport of sediment, and for relating field and physical model data

Scaling and Formulary cross sections for ion-atom impact ionization

The values of ion-atom ionization cross sections are frequently needed for many applications that utilize the propagation of fast ions through matter. When experimental data and theoretical calculations are not available, approximate formulas are frequently used. This paper briefly summarizes the most important theoretical results and approaches to cross section calculations in order to place the discussion in historical perspective and offer a concise introduction to the topic. Based on experimental data and theoretical predictions, a new fit for ionization cross sections is proposed. The range of validity and accuracy of several frequently used approximations (classical trajectory, the Born approximation, and so forth) are discussed using, as examples, the ionization cross sections of hydrogen and helium atoms by various fully stripped ions.Comment: 46 pages, 8 figure

Investigation of Reduced-Order Modeling for Aircraft Stability and Control Prediction

High-fidelity computational fluid dynamics tools offer the potential to approximate increments for ground-to-flight scaling effects, as well as to augment the dynamic damping derivative data for motion-based flight simulators. Unfortunately, the computational expense is currently prohibitive for populating a complete simulator database. This work investigates an existing surrogate-based, indicial response reduced-order model methodology as a means to efficiently augment a flight simulator database with high-fidelity nonlinear aerodynamic damping derivatives. Creation of the reduced-order model is based on the superposition integrals of the step response with the derivative of its corresponding input signal. Step responses are calculated using a computational grid motion approach that separates the effects of angle of attack and sideslip angle from angular rates, and rates from angle of attack and sideslip. It is demonstrated that the transients produced during the start of a forced-oscillation motion are captured by the reduced-order model to the level of fidelity of a comparable computational solution. Aerodynamic coefficients computed within minutes by the reduced-order model for an aircraft undergoing an 18-second half Lazy-8 maneuver and a 25-second Immelmann turn maneuver are compared with those from full computational flight solutions that required days to complete. Finally, a cost-benefit assessment is included that demonstrates a compelling advantage for this approach. d for maneuvering, flexible vehicles

Crystalline phases in chiral ferromagnets: Destabilization of helical order

In chiral ferromagnets, weak spin-orbit interactions twist the ferromagnetic order into spirals, leading to helical order. We investigate an extended Ginzburg-Landau theory of such systems where the helical order is destabilized in favor of crystalline phases. These crystalline phases are based on periodic arrangements of double-twist cylinders and are strongly reminiscent of blue phases in liquid crystals. We discuss the relevance of such blue phases for the phase diagram of the chiral ferromagnet MnSi.Comment: 6 pages, 5 figures (published version

The Resilient Local Health Department: Attributes of Survival During the Economic Crisis

The purpose of this research is to explore the attributes of local health departments (LHDs) which have survived the recent economic crises without loss of staff. A retrospective cohort study is being conducted, using the 2005 and 2010 Profile of Local Health Departments datasets from the National Association of County and City Health Officials. LHDs which responded to both surveys and which provided data on full-time equivalents (FTEs) and expenditures are included for analysis. LHDs are categorized as resilient or non-resilient based on whether the LHD gained or did not lose FTEs between 2005 and 2010 (“resilient LHD”) vs. those LHDs which experienced a loss of FTEs (“non-resilient LHD”). Resilient vs. non-resilient LHDs are compared across a range of LHD characteristics, including jurisdictional population size, expenditures, tenure of the LHD director, and presence of a governing Board of Health. Resilient LHDs (n=625) experienced an increase in the median number of FTEs from 15.8 in 2005 to 20 in 2010, while non-resilient LHDs (n=589) experienced a decline from a median of 33 to 25 FTEs. Expenditures per capita for resilient LHDs increased from a median of $35.29 to a median of$44.16, while expenditures per capita for non-resilient LHDs rose only slightly from $40.60 to$41.52.Compared to non-resilient LHDs, resilient LHDs tended to have somewhat smaller jurisdictional populations (median of 35,825 vs. median of 48,896 (z=4.374, p=0.000)) and to have a governing Board of Health in 2005 (chi-square 8.52, p=0.004) and in 2010 (chi-square=6.29, p=0.012). There were no differences in the tenure of the LHD director comparing resilient vs. non-resilient LHDs. Investigators will be conducting additional analyses, specifically exploring the differences in LHD context (local unemployment rate, poverty rate, population density, etc), sources of revenues, and array of LHD services and activities. A second set of comparisons will be made between LHDs in the lowest and the highest quintiles of percent change in FTEs between 2005 and 2010. The goal of these analyses will be to identify potential modifiable factors that may protect LHDs from subsequent negative economic conditions

Unsteady Model Estimation for Generic T-Tail Transport Aircraft Using Computational Data

Models including nonlinear and unsteady behaviors are developed for the longitudinal axis of the NASA Generic T-Tail Aircraft over a large range of angle of attack. These models are based on computational simulations of forced-oscillation tests in a wind tunnel. This work continues a recent study and an ongoing effort by NASA to improve aircraft simulations for pilot training in loss-of-control and stalled conditions. The objective of this work is to develop appropriate aerodynamic models that provide representative responses in simulation for a given class of aircraft. In the stall region, nonlinear unsteady responses are often present and may require an extended aerodynamic model compared to that used in the conventional flight envelope. In this study, two objectives are addressed. The first is to obtain representative models for the NASA Generic T-Tail aircraft over a wide range of angle of attack and the second is to continue development of a specialized CFD test technique that uses Schroeder sweeps to create information rich responses for unsteady aerodynamic model identification