Computer program provides linear sampled- data analysis for high order systems

Computer program performs transformations in the order S-to W-to Z to allow arithmetic to be completed in the W-plane. The method is based on a direct transformation from the S-plane to the W-plane. The W-plane poles and zeros are transformed into Z-plane poles and zeros using the bilinear transformation algorithm

Sensitivity of a Bolometric Interferometer to the CMB power spectrum

Context. The search for B-mode polarization fluctuations in the Cosmic Microwave Background is one of the main challenges of modern cosmology. The expected level of the B-mode signal is very low and therefore requires the development of highly sensitive instruments with low systematic errors. An appealing possibility is bolometric interferometry. Aims. We compare in this article the sensitivity on the CMB angular power spectrum achieved with direct imaging, heterodyne and bolometric interferometry. Methods. Using a simple power spectrum estimator, we calculate its variance leading to the counterpart for bolometric interferometry of the well known Knox formula for direct imaging. Results. We find that bolometric interferometry is less sensitive than direct imaging. However, as expected, it is finally more sensitive than heterodyne interferometry due to the low noise of the bolometers. It therefore appears as an alternative to direct imagers with different and possibly lower systematic errors, mainly due to the absence of an optical setup in front of the horns.Comment: 5 pages, 3 figures. This last version matches the published version (Astronomy and Astrophysics 491 3 (2008) 923-927). Sensitivity of Heterodyne Interferometers modified by a factor of tw

Nikolski\u27s Approach to the theorems of Beurling and Nyman regarding zeros of the Riemann ζ-function

In this thesis we present the proof of a theorem by Nikolai Nikolski. This theorem leads to a more general theorem by Nikolski regarding zero free regions of the Riemann ζ-function. This theorem is an improvement on the theorems that Nyman and Beurling proved in the nineteen fifties. Nikolski’s approach uses, in addition to step function approximations introduced by Nyman, distance functions to give more flexibility, including possible numerical experiments. The introduction discusses the Riemann Hypothesis, which always surrounds any study of the Riemann ζ-function. The background material discussed in this thesis gives all the necessary prerequi- sites for an understanding of the proof of the main theorem. Topics include infinite products, the Gamma function, the Riemann ζ-function, Fourier series and trans- forms, the Hardy spaces, reproducing kernels, and Blaschke factors. The focus will be on the Hardy spaces of the upper and right half-planes, whose properties are deduced using the Hardy space of the unit disk via the unitary mapping of Chapter 4. The Mellin transform is also introduced and plays a vital role in the main theorem proven in chapter 6

By-Catch: Over the Side Discards, an Assessment and an Alternative

The incidental capture and resultant mortality of numerous fin-fish and other species of marine organisms by non-selective types of fishing gear constitute a major waste of the various fishery resources. The magnitude of the discarded by-catch and its effects upon the major fisheries is examined. Specific gear types contributing to the problem will be identified. The Gulf of Mexico shrimp fishery of the U.S., which annually catches over a billion pounds of unwanted fin-fish or “trash-fish” will be examined and an evaluation of the continuing development of selective shrimp trawling gear specifically designed to reduce the incidental capture of sea turtles, fin-fish, jellyfish, and other marine organisms will be conducted. Information is also presented on other possible gear modifications and operational alternatives both domestic and foreign, directed at minimizing the impacts of this neglected but critical facet of fishery science-truly, an international fishery management problem

Neutron Diffraction Study of Engineering Materials Subjected to Complex Loadings

No studies using diffraction have specifically aimed to study the (hkl) specific shear strain of lattice planes to the application of pure shear due to applied torsion. Also no measures of strain resultant from combined loads of tension and shear stress applied simultaneously have been performed. Current techniques simply measure the planar response to axial stress and cannot provide shear strains directly. Shear moduli are not necessarily related through traditional continuum mechanics to planar Youngs’ moduli (Ehkl) from these axial experiments for all materials. This is of significance as most engineering components fail under the influence of shear stress, or combination of shear and axial stress, rather than solely under axial stress. However, even though shear is the predominant loading case and yield mechanism, no exhaustive studies have yet been carried out describing the (hkl) specific shear strain in response to applied shear stress. A new technique that has been implemented as a proof-of–concept at the 2nd Generation Neutron Residual Stress Mapping Facility (NRSF2) at Oak Ridge National Laboratory (ORNL) that is able to indirectly measure the shear response of individual hkl plane. Torsion provides a unique opportunity to study the mechanical behavior of materials subjected to pure state of shear stress. An additional technique is presented that allows for the measurement of a full strain tensor in materials subjected to complex and combined proportional loads of axial and shear stresses. These new techniques are utilized to measure the planar response of a bcc ferretic steel alloy ex situ (post loading) and in situ (during loading). A comprehensive analysis of the strain tensors derived through neutron diffraction experiments on this material measured ex situ and in situ are presented. Also, a detailed description of gauge volume location through an advanced laser tracker system is demonstrated

Cosmic microwave background constraints on cosmological models with large-scale isotropy breaking

Several anomalies appear to be present in the large-angle cosmic microwave background (CMB) anisotropy maps of WMAP, including the alignment of large-scale multipoles. Models in which isotropy is spontaneously broken (e.g., by a scalar field) have been proposed as explanations for these anomalies, as have models in which a preferred direction is imposed during inflation. We examine models inspired by these, in which isotropy is broken by a multiplicative factor with dipole and/or quadrupole terms. We evaluate the evidence provided by the multipole alignment using a Bayesian framework, finding that the evidence in favor of the model is generally weak. We also compute approximate changes in estimated cosmological parameters in the broken-isotropy models. Only the overall normalization of the power spectrum is modified significantly.Comment: Accepted for publication in Phys. Rev.

Nutritional support for head-injured patients

Copyright John Wiley & Sons. This review is published as a Cochrane Review in the Cochrane Database of Systematic Reviews 2004, Issue 3. Cochrane Reviews are regularly updated as new evidence emerges and in response to comments and criticisms, and the Cochrane Database of Systematic Reviews should be consulted for the most recent version of the Review.’ Perel, P. , Yanagawa, T. , Bunn, F. , Roberts, I. , Wentz, R. and Pierro, A. Nutritional support for head-injured patients. Cochrane Database of Systematic Reviews 2004, Issue 3. Art. No.: CD001530. DOI: 10.1002/14651858.CD001530.pub2Background: Head injury increases the body's metabolic responses, and therefore nutritional demands. Provision of an adequate supply of nutrients is associated with improved outcome. The best route for administering nutrition (parenterally (TPN) or enterally (EN)), and the best timing of administration (for example, early versus late) of nutrients needs to be established. Objectives: To quantify the effect on mortality and morbidity of alternative strategies of providing nutritional support following head injury. Search strategy: Trials were identified by computerised searches of the Cochrane Injuries Group specialised register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, National Research Register, Web of Science and other electronic trials registers. Reference lists of trials and review articles were checked. The searches were last updated in July 2006. Selection criteria: Randomised controlled trials of timing or route of nutritional support following acute traumatic brain injury. Data collection and analysis: Two authors independently abstracted data and assessed trial quality. Information was collected on death, disability, and incidence of infection. If trial quality was unclear, or if there were missing outcome data, trialists were contacted in an attempt to get further information. Main results: A total of 11 trials were included. Seven trials addressed the timing of support (early versus delayed), data on mortality were obtained for all seven trials (284 participants). The relative risk (RR) for death with early nutritional support was 0.67 (95% CI 0.41 to 1.07). Data on disability were available for three trials. The RR for death or disability at the end of follow-up was 0.75 (95% CI 0.50 to 1.11). Seven trials compared parenteral versus enteral nutrition. Because early support often involves parenteral nutrition, three of the trials are also included in the previous analyses. Five trials (207 participants) reported mortality. The RR for mortality at the end of follow-up period was 0.66 (0.41 to 1.07). Two trials provided data on death and disability. The RR was 0.69 (95% Cl 0.40 to 1.19). One trial compared gastric versus jejunal enteral nutrition, there were no deaths and the RR was not estimable. Authors' conclusions: This review suggests that early feeding may be associated with a trend towards better outcomes in terms of survival and disability. Further trials are required. These trials should report not only nutritional outcomes but also the effect on death and disability.Peer reviewe

Bandwidth in bolometric interferometry

Bolometric Interferometry is a technology currently under development that will be first dedicated to the detection of B-mode polarization fluctuations in the Cosmic Microwave Background. A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers in order to be competitive with imaging experiments. A crucial concern is that interferometers are presumed to be importantly affected by a spoiling effect known as bandwidth smearing. In this paper, we investigate how the bandwidth modifies the work principle of a bolometric interferometer and how it affects its sensitivity to the CMB angular power spectra. We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. Using an angular power spectrum estimator accounting for the bandwidth, we finally calculate the sensitivity of a broadband bolometric interferometer. A numerical simulation has been performed and confirms the analytical results. We conclude (i) that broadband bolometric interferometers allow broadband visibilities to be reconstructed whatever the kind of phase shifters used and (ii) that for dedicated B-mode bolometric interferometers, the sensitivity loss due to bandwidth smearing is quite acceptable, even for wideband instruments (a factor 2 loss for a typical 20% bandwidth experiment).Comment: 13 pages, 14 figures, submitted to A&

A study of the design expertise for plants handling hazardous materials

A study of the design expertise for plants handling hazardous material

Using non-participant observation to uncover mechanisms: insights from a realist evaluation

This article outlines how a realist evaluation of dementia care in hospitals used non-participant observation to support the refinement and testing of mechanisms likely to lead to the use of person-centred care. We found that comments and explanations of their actions from hospital staff during observation periods provided insights into the reasoning that generated their actions for care in real time. This informed subsequent data collection and analysis. Two worked examples of mechanisms first identified during non-participant observation demonstrate (1) how they were uncovered, and (2) how this informed research activities for theory refinement. Early, iterative engagement with the analytic process, primarily involving reflection and debate with the research team, maximised the potential of observation data to support surfacing underlying mechanisms, linking them to specific contexts and outcomes.Peer reviewedFinal Accepted Versio