453 research outputs found

    Towards efficient decoding of classical-quantum polar codes

    Get PDF
    Known strategies for sending bits at the capacity rate over a general channel with classical input and quantum output (a cq channel) require the decoder to implement impractically complicated collective measurements. Here, we show that a fully collective strategy is not necessary in order to recover all of the information bits. In fact, when coding for a large number N uses of a cq channel W, N I(W_acc) of the bits can be recovered by a non-collective strategy which amounts to coherent quantum processing of the results of product measurements, where I(W_acc) is the accessible information of the channel W. In order to decode the other N (I(W) - I(W_acc)) bits, where I(W) is the Holevo rate, our conclusion is that the receiver should employ collective measurements. We also present two other results: 1) collective Fuchs-Caves measurements (quantum likelihood ratio measurements) can be used at the receiver to achieve the Holevo rate and 2) we give an explicit form of the Helstrom measurements used in small-size polar codes. The main approach used to demonstrate these results is a quantum extension of Arikan's polar codes.Comment: 21 pages, 2 figures, submission to the 8th Conference on the Theory of Quantum Computation, Communication, and Cryptograph

    Live animal performance and carcass characteristics of bulls versus steers

    Get PDF
    45 pages"Consumers, increasingly, are expressing a preference for beef cuts with a high proportion of lean in relation to fat. The continued increase in consumption of beef of the Choice and Good grades suggests a preference for beef with desirable eating qualities. The production of quality lean beef is a goal that involves many aspects of animal production including breeding, feeding and management. The trend toward leaner beef carcasses and more efficient feedlot performance has focused atterition on the effect of age at the time of castration on feedlot efficiency and carcass meatiness and quality. Since the early 1950's, several reports have suggested that young bulls gain faster and more efficiently than comparable steers and that the bullock carcasses yield a greater percentage of retail cuts. Reports also indicated that the meat from young bulls was similar in palatability to meat from steers of similar age and breeding. The objectives of this st~dy were to compare the feedlot performance, qualitative and quantitative carcass characteristics of beef produced from Hereford bulls, crossbred bulls, Hereford steers castrated at 205 days, crossbred steers castrated .at 205 days, and crossbred steers castrated at birth."--Introduction.Hedrick, Harold B

    The Effects of Computer-assisted Pronunciation Readings on ESL Learners’ Use of Pausing, Stress, Intonation, and Overall Comprehensibility

    Get PDF
    With research showing the benefits of pronunciation instruction aimed at suprasegmentals (Derwing, Munro, & Wiebe, 1997, 1998; Derwing & Rossiter, 2003; Hahn, 2004; McNerney and Mendelsohn, 1992), more materials are needed to provide learners opportunities for self-directed practice. A 13-week experimental study was performed with 75 ESL learners divided into control and treatment groups. The treatment group was exposed to 11 weeks of self-directed computer-assisted practice using Cued Pronunciation Readings (CPRs). In the quasi-experimental pre-test/post-test design, speech perception and production samples were collected at Time 1 (week one of the study) and Time 2 (week 13). Researchers analyzed the treatment’s effect on the learners’ perception and production of key suprasegmental features (pausing, word stress, and sentence-final intonation), and the learners’ level of perceived comprehensibility. Results from the statistical tests revealed that the treatment had a significant effect on learners’ perception of pausing and word stress and controlled production of stress, even with limited time spent practicing CPRs in a self-directed environment

    Arbitrary Shape Deformation in CFD Design

    Get PDF
    Sculptor(R) is a commercially available software tool, based on an Arbitrary Shape Design (ASD), which allows the user to perform shape optimization for computational fluid dynamics (CFD) design. The developed software tool provides important advances in the state-of-the-art of automatic CFD shape deformations and optimization software. CFD is an analysis tool that is used by engineering designers to help gain a greater understanding of the fluid flow phenomena involved in the components being designed. The next step in the engineering design process is to then modify, the design to improve the components' performance. This step has traditionally been performed manually via trial and error. Two major problems that have, in the past, hindered the development of an automated CFD shape optimization are (1) inadequate shape parameterization algorithms, and (2) inadequate algorithms for CFD grid modification. The ASD that has been developed as part of the Sculptor(R) software tool is a major advancement in solving these two issues. First, the ASD allows the CFD designer to freely create his own shape parameters, thereby eliminating the restriction of only being able to use the CAD model parameters. Then, the software performs a smooth volumetric deformation, which eliminates the extremely costly process of having to remesh the grid for every shape change (which is how this process had previously been achieved). Sculptor(R) can be used to optimize shapes for aerodynamic and structural design of spacecraft, aircraft, watercraft, ducts, and other objects that affect and are affected by flows of fluids and heat. Sculptor(R) makes it possible to perform, in real time, a design change that would manually take hours or days if remeshing were needed

    Translator for Optimizing Fluid-Handling Components

    Get PDF
    A software interface has been devised to facilitate optimization of the shapes of valves, elbows, fittings, and other components used to handle fluids under extreme conditions. This software interface translates data files generated by PLOT3D (a NASA grid-based plotting-and- data-display program) and by computational fluid dynamics (CFD) software into a format in which the files can be read by Sculptor, which is a shape-deformation- and-optimization program. Sculptor enables the user to interactively, smoothly, and arbitrarily deform the surfaces and volumes in two- and three-dimensional CFD models. Sculptor also includes design-optimization algorithms that can be used in conjunction with the arbitrary-shape-deformation components to perform automatic shape optimization. In the optimization process, the output of the CFD software is used as feedback while the optimizer strives to satisfy design criteria that could include, for example, improved values of pressure loss, velocity, flow quality, mass flow, etc

    Risk of uterine rupture with a trial of labor in women with multiple and single prior cesarean delivery.

    Get PDF
    Journal ArticleOBJECTIVE: To determine whether the risk for uterine rupture is increased in women attempting vaginal birth after multiple cesarean deliveries. METHODS: We conducted a prospective multicenter observational study of women with prior cesarean delivery undergoing trial of labor and elective repeat operation. Maternal and perinatal outcomes were compared among women attempting vaginal birth after multiple cesarean deliveries and those with a single prior cesarean delivery. We also compared outcomes for women with multiple prior cesarean deliveries undergoing trial of labor with those electing repeat cesarean delivery. RESULTS: Uterine rupture occurred in 9 of 975 (0.9%) women with multiple prior cesarean compared with 115 of 16,915 (0.7%) women with a single prior operation (P = .37). Multivariable analysis confirmed that multiple prior cesarean delivery was not associated with an increased risk for uterine rupture. The rates of hysterectomy (0.6% versus 0.2%, P = .023) and transfusion (3.2% versus 1.6%, P < .001) were increased in women with multiple prior cesarean deliveries compared with women with a single prior cesarean delivery attempting trial of labor. Similarly, a composite of maternal morbidity was increased in women with multiple prior cesarean deliveries undergoing trial of labor compared with those having elective repeat cesarean delivery (odds ratio 1.41, 95% confidence interval 1.02-1.93). CONCLUSION: A history of multiple cesarean deliveries is not associated with an increased rate of uterine rupture in women attempting vaginal birth compared with those with a single prior operation. Maternal morbidity is increased with trial of labor after multiple cesarean deliveries, compared with elective repeat cesarean delivery, but the absolute risk for complications is small. Vaginal birth after multiple cesarean deliveries should remain an option for eligible women. LEVEL OF EVIDENCE: II-2
    • 

    corecore