5,482 research outputs found

    STOCHASTIC VORTEX BLOBS METHOD TO STUDY AXISYMMETRIC FLOWS OF INCOMPRESSIBLE VISCOUS FLUID

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    This paper presents the mathematical and computational formulations of the stochastic Vortex Blobs Method (VBM). It isshow that how the method can be used to cover axisymmetric flows of incompressible viscous fluid. Also, the initialboundary problem is solved by using the Lagrangian vortex method. This method seems to be an extension of the well known two dimensional vortex blob method. When applying and extending this method two steps are required. First, wehave to design an axisymmetric vorticity carrier by using the standard functions as complete elliptic integrals and Legendre polynomials. Second, it is necessary to formulate the appropriate Neumann problem and boundary integral equation to find the potential velocity fields. Both steps are used to describe and compute the total velocity field and formulate the Ito stochastic equations which describing the motion of vorticity carriers

    Addition of 24‐hour heart rate variability parameters to the Cardiovascular Health Study stroke risk score and prediction of incident stroke: The Cardiovascular Health Study

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    Background Heart rate variability (HRV) characterizes cardiac autonomic functioning. The association of HRV with stroke is uncertain. We examined whether 24‐hour HRV added predictive value to the Cardiovascular Health Study clinical stroke risk score (CHS‐SCORE), previously developed at the baseline examination. Methods and Results N=884 stroke‐free CHS participants (age 75.3±4.6), with 24‐hour Holters adequate for HRV analysis at the 1994–1995 examination, had 68 strokes over ≀8 year follow‐up (median 7.3 [interquartile range 7.1–7.6] years). The value of adding HRV to the CHS‐SCORE was assessed with stepwise Cox regression analysis. The CHS‐SCORE predicted incident stroke (HR=1.06 per unit increment, P=0.005). Two HRV parameters, decreased coefficient of variance of NN intervals (CV%, P=0.031) and decreased power law slope (SLOPE, P=0.033) also entered the model, but these did not significantly improve the c‐statistic (P=0.47). In a secondary analysis, dichotomization of CV% (LOWCV% ≀12.8%) was found to maximally stratify higher‐risk participants after adjustment for CHS‐SCORE. Similarly, dichotomizing SLOPE (LOWSLOPE <−1.4) maximally stratified higher‐risk participants. When these HRV categories were combined (eg, HIGHCV% with HIGHSLOPE), the c‐statistic for the model with the CHS‐SCORE and combined HRV categories was 0.68, significantly higher than 0.61 for the CHS‐SCORE alone (P=0.02). Conclusions In this sample of older adults, 2 HRV parameters, CV% and power law slope, emerged as significantly associated with incident stroke when added to a validated clinical risk score. After each parameter was dichotomized based on its optimal cut point in this sample, their composite significantly improved prediction of incident stroke during ≀8‐year follow‐up. These findings will require validation in separate, larger cohorts. Keywords: autonomic nervous system, clinical stroke risk model, heart rate variability, prediction, predictors, risk prediction, risk stratification, strok

    Stem cell clinics in the UK:a web-based study

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    Aim: Explore the nature and extent of web-based promotion of stem cell treatments marketed by clinics in the UK. Materials &amp; methods: Web-based analysis of clinics in the UK using predefined variables, with analysis of eligible clinics according to preset criteria of ethical relevance. Results: A majority (79%) of UK clinics were judged to be problematic. Information was found to be lacking, misleading or otherwise problematic in several respects, including a lack of information on risks of adverse effects, unjustifiably optimistic depictions of therapeutic effectiveness, and questionable presentational approaches such as the use of celebrity patient testimonials. Conclusion: In a majority of cases, commercial clinics in the UK portray stem cell therapies on their websites in ethically questionable ways

    Entropy generation for forced convection in a porous channel with isoflux or isothermal walls

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    A numerical study is reported to investigate the entropy generation due to forced convection in a parallel plate channel filled by a saturated porous medium. Two different thermal boundary conditions are considered being isoflux and isothermal walls. Effects of the PĂ©clet number, the porous medium shape factor, the dimensionless temperature difference for isothermal walls, the dimensionless heat flux for isoflux walls, and the Brinkman number on the Bejan number as well as the local and average dimensionless entropy generation rate are examined

    The CaSR in pathogenesis of breast cancer : a new target for early stage bone metastases

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    The Ca2+-sensing receptor (CaSR) is a class-C G protein-coupled receptor which plays a pivotal role in calciotropic processes, primarily in regulating parathyroid hormone secretion to maintain systemic calcium homeostasis. Among its non-calciotropic roles, where the CaSR sits at the intersection of myriad processes, it has steadily garnered attention as an oncogene or tumor suppressor in different organs. In maternal breast tissues the CaSR promotes lactation but in breast cancer it acts as an oncoprotein and has been shown to drive the pathogenesis of skeletal metastases from breast cancer. Even though research has made great strides in treating primary breast cancer, there is an unmet need when it comes to treatment of metastatic breast cancer. This review focuses on how the CaSR leads to the pathogenesis of breast cancer by contrasting its role in healthy tissues and tumorigenesis, and by drawing brief parallels with the tissues where it has been implicated as an oncogene. A class of compounds called calcilytics, which are CaSR antagonists, have also been surveyed in the instances where they have been used to target the receptor in cancerous tissues and constitute a proof of principle for repurposing them. Current clinical therapies for treating bone metastases from breast cancer are limited to targeting osteoclasts and a deeper understanding of the CaSR signaling nexus in this context can bolster them or lead to novel therapeutic interventions

    A simple method for serving Web hypermaps with dynamic database drill-down

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    BACKGROUND: HealthCyberMap aims at mapping parts of health information cyberspace in novel ways to deliver a semantically superior user experience. This is achieved through "intelligent" categorisation and interactive hypermedia visualisation of health resources using metadata, clinical codes and GIS. HealthCyberMap is an ArcView 3.1 project. WebView, the Internet extension to ArcView, publishes HealthCyberMap ArcView Views as Web client-side imagemaps. The basic WebView set-up does not support any GIS database connection, and published Web maps become disconnected from the original project. A dedicated Internet map server would be the best way to serve HealthCyberMap database-driven interactive Web maps, but is an expensive and complex solution to acquire, run and maintain. This paper describes HealthCyberMap simple, low-cost method for "patching" WebView to serve hypermaps with dynamic database drill-down functionality on the Web. RESULTS: The proposed solution is currently used for publishing HealthCyberMap GIS-generated navigational information maps on the Web while maintaining their links with the underlying resource metadata base. CONCLUSION: The authors believe their map serving approach as adopted in HealthCyberMap has been very successful, especially in cases when only map attribute data change without a corresponding effect on map appearance. It should be also possible to use the same solution to publish other interactive GIS-driven maps on the Web, e.g., maps of real world health problems

    An evaluation of overlying tissues to determine fetal exposure to ultrasound during the third trimester

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    Measurements of minimum and average total tissue thicknesses overlying the fetus during the third trimester were taken on 52 patients between 24 and 40 weeks gestation. Minimum total thickness of tissues constantly along the ultrasound path had a mean value of 1.75 cm, ranging from 0.40 to 3.70 cm. This corresponded to a mean attenuation of 0.87 dB MHz-1, ranging from 0.30 to 1.68 dB MHz-1. Average total thickness of tissues constantly along the ultrasound path had a mean value of 2.16 cm, ranging from 1.00 to 4.10 cm. This corresponded to a mean attenuation of 1.16 dB MHz-1, ranging from 0.64 to 2.03 dB MHz-1. Average attenuation was also calculated for all soft tissues along the ultrasound path, including the placenta. The resulting average attenuation was 0.47 dB cm-1 MHz-1. Maternal weight at the time of ultrasound examination had significant correlation with minimum and average ultrasound attenuation by tissues constantly along the ultrasound path. The R2 value was 46.7% for minimum attenuation (p-value p-value 2 value of the model that included all three variables was 57.2% (p-value p-value &lt; 0.0001) for average attenuation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31864/1/0000814.pd

    Effect of cryogenic treatment on drill tool for enhancing metal cutting operation of aluminium alloy IS737.Gr19000

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    Drilling is the hole making process on the component face with the aid of a twisted drillbit. Normal drill bits easily wear out through penetration of drill bit into the workpiece material due to force generated in the drilling operation. So this work tries to investigate the machining parameters with cryogenically treated drill bits on various responses. Cryogenic treatment is one of the thermal engineering processes, which is used to cool the material from the temperature of −150 °C to −273 °C. This research work utilizes cryogenically treated drill tools for investigating the drilling performance on aluminium alloy (IS737.Gr19000) workpiece material. The independent variables and dependent variables are studied in this experimental analysis are spindle speed, feed rate and machining time, entry and exit burr dimensions, thrust force, torque, Ovality, surface roughness, respectively. The theoretical investigation is also carried out with statistical analysis. The response surface methodology with Box Behnken design the 17 experimental runs with 9 different treated drill tools are carried out. The cryogenically treated drill bit gave good results on burr dimensions, Ovality, surface roughness on drilled hole quality. The tool wear performance was also studied with drill tool geometry measurements with the tool makers microscope. The cryogenically treated drill bits gave the best results than the normal drill bit
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