Robust single-parameter quantized charge pumping

This paper investigates a scheme for quantized charge pumping based on single-parameter modulation. The device was realized in an AlGaAs-GaAs gated nanowire. We find a remarkable robustness of the quantized regime against variations in the driving signal, which increases with applied rf power. This feature together with its simple configuration makes this device a potential module for a scalable source of quantized current.Comment: Submitted to Appl. Phys. Let

Single-parameter non-adiabatic quantized charge pumping

Controlled charge pumping in an AlGaAs/GaAs gated nanowire by single-parameter modulation is studied experimentally and theoretically. Transfer of integral multiples of the elementary charge per modulation cycle is clearly demonstrated. A simple theoretical model shows that such a quantized current can be generated via loading and unloading of a dynamic quasi-bound state. It demonstrates that non-adiabatic blockade of unwanted tunnel events can obliterate the requirement of having at least two phase-shifted periodic signals to realize quantized pumping. The simple configuration without multiple pumping signals might find wide application in metrological experiments and quantum electronics.Comment: 4 pages, 4 figure

Integrated quantized electronics: a semiconductor quantized voltage source

The Josephson effect in superconductors links a quantized output voltage Vout = f \cdot(h/2e) to the natural constants of the electron's charge e, Planck's constant h, and to an excitation frequency f with important applications in electrical quantum metrology. Also semiconductors are routinely applied in electrical quantum metrology making use of the quantum Hall effect. However, despite their broad range of further applications e.g. in integrated circuits, quantized voltage generation by a semiconductor device has never been obtained. Here we report a semiconductor quantized voltage source generating quantized voltages Vout = f\cdot(h/e). It is based on an integrated quantized circuit of a single electron pump operated at pumping frequency f and a quantum Hall device monolithically integrated in series. The output voltages of several \muV are expected to be scalable by orders of magnitude using present technology. The device might open a new route towards the closure of the quantum metrological triangle. Furthermore it represents a universal electrical quantum reference allowing to generate quantized values of the three most relevant electrical units of voltage, current, and resistance based on fundamental constants using a single device.Comment: 15 pages, 3 figure

Analysis of the Public Works Service Request Process For Naval Facilities Engineering Command Northwest

EMBA Project ReportEXECUTIVE SUMMARY: The goal of this project is to analyze the service request portion of the Public Works Business Line (PWBL) processes for Naval Facilities Engineering Command (NAVFAC) Northwest. All four PWBL Product Lines are included in the analysis. These Product Lines are Facility Management and Sustainment (FM&S), Facility Service Contract Management and Facility Services (FMFS), Base Support Vehicles and Equipment (BSVE), and Utilities and Energy Management (UEM). The perceived problem is that there are instances of confusion and inaccuracies regarding funding responsibilities and service levels resulting from prior years of organizational changes and functional transfers. The research examines the process used to contact NAVFAC to request service, the process NAVFAC uses to validate that the requested service is funded and authorized, and applicable documents, agreements, and information used by the participants. By conducting interviews with fifty process participants, sufficient information is gathered to map the current service request process. Process maps are provided for each product line. The maps show the decision points involved in the interaction between the customer and NAVFAC field staff in the request process. The interview results confirm that the perceived problems do exist in some areas and product lines. Interviewed personnel credit NAVFAC for improvements already accomplished in many areas. Remaining problems common to multiple product lines and cited most often include limited resources, limited access to NAVFAC information, unclear service level and funding source information, and insufficient sharing of long range planning information between customers and NAVFAC. In addition, the use of authorized customer representatives and regular customer meetings work well when used and could be leveraged in other areas. After conducting root cause analysis, recommendations are provided that address the consequences of the problems and align with NAVFAC strategic goals. These include communication improvements to increase accessibility of information, documentation improvements to reduce confusion, and training suggestions to improve understanding and consistency. The recommendations are charted with benefits and difficulty of implementation to assist NAVFAC in deciding which to consider implementing first (i.e., those with the most benefit for the least initial investment). A tool is included to allow the client to adjust the value weighting of the benefits and implementation difficulty based on their own preferences. Using equal weighting the recommendations to consider first are: a) the communication recommendations including an accessible web site, holding a customer symposium, and publications, b) the documentation recommendation of posting the process maps, and c) the training recommendations to hold internal briefings for NAVFAC personnel and acquisition briefings for customers. Implementation of even some of the recommendations provided in this study will achieve many benefits in operational effectiveness for both NAVFAC and its supported Commands.http://archive.org/details/analysisofpublic10945707

Gender and the evaluation of honest leaders - examining the link between gender as the Hhonesty source and leadership perceptions

This thesis investigates the link between honesty, gender, and leadership effectiveness. It hypothesizes, based on literature that honesty leads to a higher leadership effectiveness rating. Furthermore, it suggests that there is a difference in leadership effectiveness rating when being (dis-)honest based on the leader’s gender. The experimental between-subjects study of 158 participants shows a significant positive link between honesty and leadership effectiveness rating. However, it could not find any gender differences in leadership effectiveness when the leader acts (dis-)honestly. This contributes to the literature on the effects of honesty and gender on leadership effectiveness

Analysis of Alternatives: Multivariate Considerations

The Aeronautical System Center (ASC) is developing a Simulation and Analysis Facility (SIMAF) that will link models, simulations, hardware-in-the-loop, and system-in-the-loop resources to create a robust virtual environment supporting assessment of alternate systems in the defense acquisition process. ENS is assisting ASC with scenario development, experimental design, and battleroom visualization efforts for a SIMAF capability demonstration. This thesis uses multivariate analysis and visualization tools to develop an approach for reducing the dimensionality of multiple campaign level measures of effectiveness for a notional Analysis of Alternatives (AoA) study. Additionally, the thesis advances an AoA visualization paradigm for the SIMAF capability demonstration. The results of this study suggest that multivariate data reduction techniques and user interactive visualization of multivariate analysis results can be employed to combine multiple MOEs into a reduced set of interpretable factors capturing the operational effectiveness performance of competing acquisition alternatives. The thesis research also successfully demonstrated a visual data mining approach applied to the visualization of campaign level analysis results and the cost/effectiveness integration of an AoA effort

Kinetics of four-wave mixing for a 2D magneto-plasma in strong magnetic fields

We investigate the femtosecond kinetics of an optically excited 2D magneto-plasma at intermediate and high densities under a strong magnetic field perpendicular to the quantum well (QW). We assume an additional weak lateral confinement which lifts the degeneracy of the Landau levels partially. We calculate the femtosecond dephasing and relaxation kinetics of the laser pulse excited magneto-plasma due to bare Coulomb potential scattering, because screening is under these conditions of minor importance. In particular the time-resolved and time-integrated four-wave mixing (FWM) signals are calculated by taking into account three Landau subbands in both the valance and the conduction band assuming an electron-hole symmetry. The FWM signals exhibit quantum beats mainly with twice the cyclotron frequency. Contrary to general expectations, we find no pronounced slowing down of the dephasing with increasing magnetic field. On the contrary, one obtains a decreasing dephasing time because of the increase of the Coulomb matrix elements and the number of states in a given Landau subband. In the situation when the loss of scattering channels exceeds these increasing effects, one gets a slight increase at the dephasing time. However, details of the strongly modulated scattering kinetics depend sensitively on the detuning, the plasma density, and the spectral pulse width relative to the cyclotron frequency.Comment: 13 pages, in RevTex format, 10 figures, Phys. Rev B in pres

Ultrafast Coulomb-induced dynamics of 2D magnetoexcitons

We study theoretically the ultrafast nonlinear optical response of quantum well excitons in a perpendicular magnetic field. We show that for magnetoexcitons confined to the lowest Landau levels, the third-order four-wave-mixing (FWM) polarization is dominated by the exciton-exciton interaction effects. For repulsive interactions, we identify two regimes in the time-evolution of the optical polarization characterized by exponential and {\em power law} decay of the FWM signal. We describe these regimes by deriving an analytical solution for the memory kernel of the two-exciton wave-function in strong magnetic field. For strong exciton-exciton interactions, the decay of the FWM signal is governed by an antibound resonance with an interaction-dependent decay rate. For weak interactions, the continuum of exciton-exciton scattering states leads to a long tail of the time-integrated FWM signal for negative time delays, which is described by the product of a power law and a logarithmic factor. By combining this analytic solution with numerical calculations, we study the crossover between the exponential and non-exponential regimes as a function of magnetic field. For attractive exciton-exciton interaction, we show that the time-evolution of the FWM signal is dominated by the biexcitonic effects.Comment: 41 pages with 11 fig

Clinically Actionable Hypercholesterolemia and Hypertriglyceridemia in Children with Nonalcoholic Fatty Liver Disease

OBJECTIVE: To determine the percentage of children with nonalcoholic fatty liver disease (NAFLD) in whom intervention for low-density lipoprotein cholesterol or triglycerides was indicated based on National Heart, Lung, and Blood Institute guidelines. STUDY DESIGN: This multicenter, longitudinal cohort study included children with NAFLD enrolled in the National Institute of Diabetes and Digestive and Kidney Diseases Nonalcoholic Steatohepatitis Clinical Research Network. Fasting lipid profiles were obtained at diagnosis. Standardized dietary recommendations were provided. After 1 year, lipid profiles were repeated and interpreted according to National Heart, Lung, and Blood Institute Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction. Main outcomes were meeting criteria for clinically actionable dyslipidemia at baseline, and either achieving lipid goal at follow-up or meeting criteria for ongoing intervention. RESULTS: There were 585 participants, with a mean age of 12.8 years. The prevalence of children warranting intervention for low-density lipoprotein cholesterol at baseline was 14%. After 1 year of recommended dietary changes, 51% achieved goal low-density lipoprotein cholesterol, 27% qualified for enhanced dietary and lifestyle modifications, and 22% met criteria for pharmacologic intervention. Elevated triglycerides were more prevalent, with 51% meeting criteria for intervention. At 1 year, 25% achieved goal triglycerides with diet and lifestyle changes, 38% met criteria for advanced dietary modifications, and 37% qualified for antihyperlipidemic medications. CONCLUSIONS: More than one-half of children with NAFLD met intervention thresholds for dyslipidemia. Based on the burden of clinically relevant dyslipidemia, lipid screening in children with NAFLD is warranted. Clinicians caring for children with NAFLD should be familiar with lipid management