6,086 research outputs found

    Cut-off rate calculations for the outer channel in a concatenated cooling system

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    Concatenated codes were long used as a practical means of achieving long block or constraint lengths for combating errors on very noisy channels. The inner and outer encoders are normally separated by an interleaver, so that decoded error bursts coming from the inner decoder are randomized before entering the outer decoder. The effectiveness of this interleaver is examined by calculating the cut-off rate of the outer channel seen by the outer decoder with and without interleaving. Interleaving never hurts the performance of a concatenated code, and when the inner code rate is near the cut-off rate of the inner channel, interleaving significantly improves code performance

    Topological Defects in Twisted Bundles of Two-Dimensionally Ordered Filaments

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    Twisted assemblies of filaments in ropes, cables and bundles are essential structural elements in wide use in macroscopic materials as well as within the cells and tissues of living organisms. We develop the unique, non-linear elastic properties of twisted filament bundles that derive from generic properties of two-dimensional line-ordered materials. Continuum elasticity reveals a formal equivalence between the elastic stresses induced by bundle twist and those induced by the positive curvature in thin, elastic sheets. These geometrically-induced stresses can be screened by 5-fold disclination defects in lattice packing, and we predict a discrete spectrum elastic energy groundstates associated with integer numbers of disclinations in cylindrical bundles. Finally, we show that elastic-energy groundstates are extremely sensitive to defect position in the cross-section, with off-center disclinations driving the entire bundle to buckle, adopting globally writhing configurations.Comment: 4.1 pages; 3 figure

    Informing retention in longitudinal cohort studies through a social marketing lens: Raine Study Generation 2 participants' perspectives on benefits and barriers to participation

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    BACKGROUND: Longitudinal cohort studies have made significant contributions to medical discoveries and provide the impetus for health interventions which reduce the risk of disease. Establishing and maintaining these cohorts is challenging and costly. While some attrition is unavoidable, maintaining a sufficient number of participants ensures that results remain representative and free from bias. Numerous studies have investigated ways to reduce attrition but few studies have sought to understand the experience of participants, and none have examined this through a social marketing framework. This first paper in a two part-series describes participants' experiences according to: benefits, barriers, motivators and influencers. The second paper uses this understanding to address issues relating to the 4Ps (product, price, place, promotion) of social marketing. METHODS: Participants were recruited from the Raine Study, a pregnancy cohort study that has been running in Western Australia since 1989. Qualitative interviews were conducted with 29 active and inactive participants from the Generation 2 cohort, who were originally enrolled in the Raine Study at birth by their parents (Generation 1). 'Active' participants (n = 17) were defined as those who agreed to attend their 27 year follow-up, while 'inactive' (n = 12) participants were defined as those who had not attended either of the past two follow-ups (at 22 and 27 years). RESULTS: There were considerable differences between active and inactive participants, with active participants perceiving far more personal and collective benefits from their participation. Inactive participants described being constrained by structural barriers around work and life, whereas active participants were able to overcome them to attend follow-ups. Inactive participants also described the value of extrinsic incentives which might motivate their attendance, and active participants described the role of their parents as significant influencers in their propensity to remain in the study. CONCLUSIONS: This paper provides rich descriptions of what participation in a long-running study means to participants. Use of a social marketing framework ensured that participants were constructed as 'human consumers' who are influenced by individual and broader social systems. Understanding participants in this way means that differentiated strategies can be tailored to enhance retention

    Diagnostic errors in paediatric cardiac intensive care

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    AbstractIntroductionDiagnostic errors cause significant patient harm and increase costs. Data characterising such errors in the paediatric cardiac intensive care population are limited. We sought to understand the perceived frequency and types of diagnostic errors in the paediatric cardiac ICU.MethodsPaediatric cardiac ICU practitioners including attending and trainee physicians, nurse practitioners, physician assistants, and registered nurses at three North American tertiary cardiac centres were surveyed between October 2014 and January 2015.ResultsThe response rate was 46% (N=200). Most respondents (81%) perceived that diagnostic errors harm patients more than five times per year. More than half (65%) reported that errors permanently harm patients, and up to 18% perceived that diagnostic errors contributed to death or severe permanent harm more than five times per year. Medication side effects and psychiatric conditions were thought to be most commonly misdiagnosed. Physician groups also ranked pulmonary overcirculation and viral illness to be commonly misdiagnosed as bacterial illness. Inadequate care coordination, data assessment, and high clinician workload were cited as contributory factors. Delayed diagnostic studies and interventions related to the severity of the patient’s condition were thought to be the most commonly reported process breakdowns. All surveyed groups ranked improving teamwork and feedback pathways as strategies to explore for preventing future diagnostic errors.ConclusionsPaediatric cardiac intensive care practitioners perceive that diagnostic errors causing permanent harm are common and associated more with systematic and process breakdowns than with cognitive limitations.</jats:sec

    Effect of Breed, Sex, and Final Weight on Feedlot Performance, Carcass Characteristics, and Meat Palatability of Lambs

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    The objective of this project was to study the effect of slaughter weight (heavy vs light), sex (ram vs wether) and breed (Targhee vs Suffolk x Targhee) of lambs on feedlot performance, carcass characteristics and palatablity attributes. In addition, year (1975 vs 1976) and type of birth (single vs multiple) were included in the analysis

    Predicting Beef Palatability

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    The search for factors influencing the palatability of beef continues. The relative importance of variables in the USDA quality grading system that currently predicts acceptability and palatability has been questioned. The effect of marbling on palatability is one of the more controversial aspects. Marbling is one of the prime factors in determining the quality grade of a beef carcass and researchers have shown that other variables may play an equal or more important role influencing the eating quality of beef. The purpose of this study was to evaluate the accuracy of commonly-used predictors of palatability and to consider the possible influence of other carcass measures as predictors of palatability. Palatability, as defined in this study, was measured by the subjective taste panel scores for flavor, juiciness and tenderness. Tenderness mas measured objectively with the Warner-Bratzler shear instrument

    Energy Level in Ration, Market Weight and Types of Cattle

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    The effect of body size on feed efficiency has been the subject of research for several years. Evidence was presented from some of the early research that body weight is unrelated to feed efficiency. Recent research has also shown that current recommended net energy requirements, such as those by the National Research Council, for growing and finishing beef cattle are valid for various sizes and types of beef animals. Large-bodied cattle gaining at a faster rate require more feed and should be fed ro heavier weights to reach best market grade

    How Energy Level in Ration, Market Weight and Type of Cattle Influence Beef Carcass Traits

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    An experiment reported in this publication under the title Energy Level in Ration, Market Weight and Types of Cattle provided material to observe the influence of the three factors listed on beef carcass characteristics. Details describing the cattle, rations and market weights are presented in that report

    The laboratory telerobotic manipulator program

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    New opportunities for the application of telerobotic systems to enhance human intelligence and dexterity in the hazardous environment of space are presented by the NASA Space Station Program. Because of the need for significant increases in extravehicular activity and the potential increase in hazards associated with space programs, emphasis is being heightened on telerobotic systems research and development. The Laboratory Telerobotic Manipulator (LTM) program is performed to develop and demonstrate ground-based telerobotic manipulator system hardware for research and demonstrations aimed at future NASA applications. The LTM incorporates traction drives, modularity, redundant kinematics, and state-of-the-art hierarchical control techniques to form a basis for merging the diverse technological domains of robust, high-dexterity teleoperations and autonomous robotic operation into common hardware to further NASA's research
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