8,873 research outputs found

    Optimization of conventional spinning process parameters by means of numerical simulation and statistical analysis

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    Research in sheet metal spinning has increased due to a greater demand, especially in the transportation industries, for parts with very high strength-to-weight ratios with low cost. Spinning processes are efficient in producing such characteristics and there is great flexibility in the process with a relatively low tool cost. The objectives of this investigation are to define the critical working parameters in spinning, show the effects of these factors on product quality characteristics, and to optimize the working parameters. The example used is the conventional spinning of a cylindrical cup. Optimization of the process is undertaken through the use of statistical analysis tools applied to the data produced from three-dimensional finite element simulations of the process. This has been achieved by generating two ‘designs of experiments’.The first identifies the most critical parameters for product formability and the second shows how these critical parameters affect the product quality. The results show that feed rate,relative clearance, and roller nose radius are the most important working parameters and significantly affect average thickness, thickness variation, and springback of the cylindrical cup. An additional 22 per cent improvement in the product quality characteristic is gained through using the optimum working parameters

    Normal frames for non-Riemannian connections

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    The principal properties of geodesic normal coordinates are the vanishing of the connection components and first derivatives of the metric components at some point. It is well-known that these hold only at points where the connection has vanishing torsion and non-metricity. However, it is shown that normal frames, possessing the essential features of normal coordinates, can still be constructed when the connection is non-Riemannian.Comment: 4 pages, plain TeX. To appear in Class. Quantum Gra

    Gender-role development in toddlers: The association between parental gender-role orientation and toddler\u27s gender-typed behavior

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    Associations between the gender-role orientation of parents and the toy-play behavior of first-born infants were investigated. Fifteen fathers ( M age = 31.13, SD = 4.26) and 46 mothers ( M age = 28.13, SD = 4.97) completed self-administered questionnaires which included questions on feedback to play with gender-typed toys. ANOVA results indicated that mothers provided more masculine-typed toys for their sons than their daughters, and more feminine-typed toys for their daughters than their sons; fathers provided more feminine-typed toys for their daughters than their sons. In addition, mothers provided more encouragement to same-gender-typed play than cross-gender-typed play for both masculine- and feminine-typed toys, while fathers provided more encouragement to their daughters playing with feminine-typed toys than their sons. Results are discussed in terms of the gender-role socialization processes in which parents of young children engage, and the possibility of bidirectional socialization processes

    Pain Perception after Isometric Exercise in Women with Fibromyalgia

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    Objective: The purpose of this study was to identify exercise protocols incorporating isometric contractions that provide pain relief in women with fibromyalgia. Design: A before-after trial. Setting: A physical therapy department in an academic setting. Participants: Fifteen women (mean ± SD, 52 ± 11y) with fibromyalgia. Interventions: Subjects completed 4 sessions: 1 familiarization and 3 experimental. The following randomized experimental sessions involved the performance of isometric contractions with the elbow flexor muscles that varied in intensity and duration: (1) 3 maximal voluntary contractions (MVCs), (2) 25% MVC held to task failure, and (3) 25% MVC held for 2 minutes. Main Outcome Measures: Experimental pain (pain threshold and pain rating), Fibromyalgia Impact Questionnaire, and fibromyalgia pain intensity (visual analog scale). Results: After all 3 isometric contractions, there was considerable variability between subjects in the pain response. Based on the changes in experimental pain, subjects were divided into 3 groups (increase, decrease, no change in pain). Multiple regression analysis revealed that age, baseline experimental pain, and change in fibromyalgia pain intensity were significant predictors of the experimental pain response after the isometric contractions. Conclusions: We identified subgroups of women with fibromyalgia based on how they perceived pain after isometric contractions. The greatest pain relief for women with fibromyalgia occurred at a younger age and in women with the greatest experimental pain before exercise. Additionally, we established a link between experimental and clinical pain relief after the performance of isometric contractions

    A limited speech recognition system 2 Final report

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    Limited speech recognition system for computer voice lin

    A Strategy for Imidazotetrazine Prodrugs with Anti-cancer Activity Independent of MGMT and MMR

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    The imidazotetrazine ring is an acid-stable precursor and prodrug of highly-reactive alkyl diazonium ions. We have shown that this reactivity can be managed productively in an aqueous system for the generation of aziridinium ions with 96% efficiency. The new compounds are potent DNA alkylators and have antitumor activity independent of the O6-methylguanine-DNA methyltransferase and DNA mismatch repair constraints that limit the use of temozolomide

    SPARC-Dependent Cardiomyopathy in Drosophila

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    Background—The Drosophila heart is an important model for studying the genetics underpinning mammalian cardiac function. The system comprises contractile cardiomyocytes, adjacent to which are pairs of highly endocytic pericardial nephrocytes that modulate cardiac function by uncharacterized mechanisms. Identifying these mechanisms and the molecules involved is important because they may be relevant to human cardiac physiology. Methods and Results—This work aimed to identify circulating cardiomodulatory factors of potential relevance to humans using the Drosophila nephrocyte-cardiomyocyte system. A Kruppel-Like Factor 15 (dKlf15) loss-of-function strategy was used to ablate nephrocytes and then heart function and the hemolymph proteome were analysed. Ablation of nephrocytes led to a severe cardiomyopathy characterized by a lengthening of diastolic interval. Rendering adult nephrocytes dysfunctional by disrupting their endocytic function or temporally-conditional knock-down of dKlf15 led to a similar cardiomyopathy. Proteomics revealed that nephrocytes regulate the circulating levels of many secreted proteins, the most notable of which was the evolutionarily conserved matricellular protein SPARC (Secreted Protein Acidic and Rich in Cysteine), a protein involved in mammalian cardiac function. Finally, reducing SPARC gene dosage ameliorated the cardiomyopathy that developed in the absence of nephrocytes. Conclusions—The data implicate SPARC in the non-cell autonomous control of cardiac function in Drosophila and suggest that modulation of SPARC gene expression may ameliorate cardiac dysfunction in humans

    Orbital and stochastic far-UV variability in the nova-like system V3885 Sgr

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    Highly time-resolved time-tagged FUSE satellite spectroscopic data are analysed to establish the far-ultraviolet (FUV) absorption line characteristics of the nova-like cataclysmic variable binary, V3885 Sgr. We determine the temporal behaviour of low (Ly_beta, CIII, NIII) and high (SIV, PV, OVI) ion species, and highlight corresponding orbital phase modulated changes in these lines. On average the absorption troughs are blueshifted due to a low velocity disc wind outflow. Very rapid (~ 5 min) fluctuations in the absorption lines are isolated, which are indicative of stochastic density changes. Doppler tomograms of the FUV lines are calculated which provide evidence for structures where a gas stream interacts with the accretion disc. We conclude that the line depth and velocity changes as a function of orbital phase are consistent with an asymmetry that has its origin in a line-emitting, localised disc-stream interaction region.Comment: Accepted for publication in MNRA

    Service evaluation to establish the sensitivity, specificity and additional value of broad-range 16S rDNA PCR for the diagnosis of infective endocarditis from resected endocardial material in patients from eight UK and Ireland hospitals

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    Infective endocarditis (IE) can be diagnosed in the clinical microbiology laboratory by culturing explanted heart valve material. We present a service evaluation that examines the sensitivity and specificity of a broad-range 16S rDNA polymerase chain reaction (PCR) assay for the detection of the causative microbe in culture-proven and culture-negative cases of IE. A clinical case-note review was performed for 151 patients, from eight UK and Ireland hospitals, whose endocardial specimens were referred to the Microbiology Laboratory at Great Ormond Street Hospital (GOSH) for broad-range 16S rDNA PCR over a 12-year period. PCR detects the causative microbe in 35/47 cases of culture-proven IE and provides an aetiological agent in 43/69 cases of culture-negative IE. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the 16S rDNA PCR assay were calculated for this series of selected samples using the clinical diagnosis of IE as the reference standard. The values obtained are as follows: sensitivity = 67 %, specificity = 91 %, PPV = 96 % and NPV = 46 %. A wide range of organisms are detected by PCR, with Streptococcus spp. detected most frequently and a relatively large number of cases of Bartonella spp. and Tropheryma whipplei IE. PCR testing of explanted heart valves is recommended in addition to culture techniques to increase diagnostic yield. The data describing the aetiological agents in a large UK and Ireland series of culture-negative IE will allow future development of the diagnostic algorithm to include real-time PCR assays targeted at specific organisms
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