Comparing resolved-sideband cooling and measurement-based feedback cooling on an equal footing: analytical results in the regime of ground-state cooling

We show that in the regime of ground-state cooling, simple expressions can be derived for the performance of resolved-sideband cooling --- an example of coherent feedback control --- and optimal linear measurement-based feedback cooling for a harmonic oscillator. These results are valid to leading order in the small parameters that define this regime. They provide insight into the origins of the limitations of coherent and measurement-based feedback for linear systems, and the relationship between them. These limitations are not fundamental bounds imposed by quantum mechanics, but are due to the fact that both cooling methods are restricted to use only a linear interaction with the resonator. We compare the performance of the two methods on an equal footing --- that is, for the same interaction strength --- and confirm that coherent feedback is able to make much better use of the linear interaction than measurement-based feedback. We find that this performance gap is caused not by the back-action noise of the measurement but by the projection noise. We also obtain simple expressions for the maximal cooling that can be obtained by both methods in this regime, optimized over the interaction strength.Comment: 14 pages, 2 png figures; v2: revised for publicatio

Integrating Research Data Management into Geographical Information Systems

Ocean modelling requires the production of high-fidelity computational meshes upon which to solve the equations of motion. The production of such meshes by hand is often infeasible, considering the complexity of the bathymetry and coastlines. The use of Geographical Information Systems (GIS) is therefore a key component to discretising the region of interest and producing a mesh appropriate to resolve the dynamics. However, all data associated with the production of a mesh must be provided in order to contribute to the overall recomputability of the subsequent simulation. This work presents the integration of research data management in QMesh, a tool for generating meshes using GIS. The tool uses the PyRDM library to provide a quick and easy way for scientists to publish meshes, and all data required to regenerate them, to persistent online repositories. These repositories are assigned unique identifiers to enable proper citation of the meshes in journal articles.Comment: Accepted, camera-ready version. To appear in the Proceedings of the 5th International Workshop on Semantic Digital Archives (http://sda2015.dke-research.de/), held in Pozna\'n, Poland on 18 September 2015 as part of the 19th International Conference on Theory and Practice of Digital Libraries (http://tpdl2015.info/

The Founding of an Urban Charter School: Three Years of Academic Growth and Key School Characteristics

The Kauffman School is a public charter school that serves students from low-income neighborhoods in Kansas City, Missouri. This paper used a matched comparison group design to estimate the impacts of the Kauffman School on student achievement, attendance, and suspensions. We found that the Kauffman School had positive and statistically significant impacts on student achievement in mathematics, reading, and science. This paper also used surveys, interviews, focus groups, and classroom observations to describe the hallmarks and operations of the Kauffman School and explore possible mechanisms for its effects, informing the literature on school effectiveness. We found evidence that the Kauffman School's hallmarks are largely being implemented faithfully, and that key stakeholders believe the Kauffman School's methods are having a positive influence on students' behavior, attitudes, and performance

A Sensitivity and Array-Configuration Study for Measuring the Power Spectrum of 21cm Emission from Reionization

Telescopes aiming to measure 21cm emission from the Epoch of Reionization must toe a careful line, balancing the need for raw sensitivity against the stringent calibration requirements for removing bright foregrounds. It is unclear what the optimal design is for achieving both of these goals. Via a pedagogical derivation of an interferometer's response to the power spectrum of 21cm reionization fluctuations, we show that even under optimistic scenarios, first-generation arrays will yield low-SNR detections, and that different compact array configurations can substantially alter sensitivity. We explore the sensitivity gains of array configurations that yield high redundancy in the uv-plane -- configurations that have been largely ignored since the advent of self-calibration for high-dynamic-range imaging. We first introduce a mathematical framework to generate optimal minimum-redundancy configurations for imaging. We contrast the sensitivity of such configurations with high-redundancy configurations, finding that high-redundancy configurations can improve power-spectrum sensitivity by more than an order of magnitude. We explore how high-redundancy array configurations can be tuned to various angular scales, enabling array sensitivity to be directed away from regions of the uv-plane (such as the origin) where foregrounds are brighter and where instrumental systematics are more problematic. We demonstrate that a 132-antenna deployment of the Precision Array for Probing the Epoch of Reionization (PAPER) observing for 120 days in a high-redundancy configuration will, under ideal conditions, have the requisite sensitivity to detect the power spectrum of the 21cm signal from reionization at a 3\sigma level at k<0.25h Mpc^{-1} in a bin of \Delta ln k=1. We discuss the tradeoffs of low- versus high-redundancy configurations.Comment: 34 pages, 5 figures, 2 appendices. Version accepted to Ap

Mutations in the Lipopolysaccharide Biosynthesis Pathway Interfere with Crescentin-Mediated Cell Curvature in Caulobacter crescentus

Bacterial cell morphogenesis requires coordination among multiple cellular systems, including the bacterial cytoskeleton and the cell wall. In the vibrioid bacterium Caulobacter crescentus, the intermediate filament-like protein crescentin forms a cell envelope-associated cytoskeletal structure that controls cell wall growth to generate cell curvature. We undertook a genetic screen to find other cellular components important for cell curvature. Here we report that deletion of a gene (wbqL) involved in the lipopolysaccharide (LPS) biosynthesis pathway abolishes cell curvature. Loss of WbqL function leads to the accumulation of an aberrant Opolysaccharide species and to the release of the S layer in the culture medium. Epistasis and microscopy experiments show that neither S-layer nor O-polysaccharide production is required for curved cell morphology per se but that production of the altered O-polysaccharide species abolishes cell curvature by apparently interfering with the ability of the crescentin structure to associate with the cell envelope. Our data suggest that perturbations in a cellular pathway that is itself fully dispensable for cell curvature can cause a disruption of cell morphogenesis, highlighting the delicate harmony among unrelated cellular systems. Using the wbqL mutant, we also show that the normal assembly and growth properties of the crescentin structure are independent of its association with the cell envelope. However, this envelope association is important for facilitating the local disruption of the stable crescentin structure at the division site during cytokinesis

A Composite Damage Tolerance Simulation Technique to Augment the Building Block Approach

Aerospace structures comprised of composite materials are traditionally certified empirically via the Building Block Approach (BBA). While this approach has been performed successfully in the past, it is expensive and time consuming. One means to improve the overall efficiency of composite structural certification is to reduce the cost of the BAA by eliminating the need for some tests by incorporating damage analysis tools. For an analysis to replace a given test, the tool must first be validated using other similar test data. The subject of this paper is a description of an analysis technique for simulating compression after damage strength of a solid laminate. The analysis technique is one that is practical for use in an applied engineering context due to efforts to minimize necessary computational resources and complexity of the model

Association of C2, a derivative of the radial artery pressure waveform, with new onset of type 2 diabetes mellitus: the MESA study.

BackgroundAlthough microvascular dysfunction is known to result from diabetes, it might also lead to diabetes. Lower values of C2, a derivative of the radial artery pressure waveform, indicate microvascular dysfunction and predict hypertension and cardiovascular disease (CVD). We studied the association of C2 with incident diabetes in subjects free of overt CVD.MethodsAmong multi-ethnic participants (n = 5214), aged 45-84&nbsp;years with no diabetes, C2 was derived from the radial artery pressure waveform. Incident diabetes (N = 651) was diagnosed as new fasting glucose ≥ 126&nbsp;mg/dL or antidiabetic medicine over ~ 10&nbsp;years. The relative incidence density (RID) for incident diabetes per standard deviation (SD) of C2 was studied during ~ 10&nbsp;years follow-up using four levels of adjustment.ResultsMean C2 at baseline was 4.58 ± 2.85&nbsp;mL/mmHg × 100. The RID for incident diabetes per SD of C2 was 0.90 (95% CI 0.82-0.99, P = 0.03). After adjustment for demographics plus body size, the corresponding RID was 0.81 (95% CI 0.73-0.89, P &lt; 0.0001); body mass index (BMI) was the dominant covariate here. After adjustment for demographics plus cardiovascular risk factors, the RID was 0.98 (95% CI 0.89, 1.07, P = 0.63). After adjustment for all the parameters in the previous models, the RID was 0.87 (95% CI 0.78, 0.96, P = 0.006).ConclusionsIn a multi-ethnic sample free of overt CVD and diabetes at baseline, C2 predicted incident diabetes after adjustment for demographics, BMI and CVD risk factors. Differences in arterial blood pressure wave morphology may indicate a long-term risk trajectory for diabetes, independently of body size and the classical risk factors