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The surgical creation of an artery-vein connection via a Brachicephalic fistula (BCF) in patients with end stage renal disease (ESRD) provides a unique opportunity to study blood vessel response mechanisms to extreme hemodynamic conditions in relatively short timeframes. After BCF creation, the flow rate in the vein increases by an order of magnitude leading to separated flows and corresponding abnormally low, or negative, wall shear stress (WSS) in the curved arch segment of the cephalic vein. Locations of abnormally low WSS are shown to correlate with development of neointimal hyperplasia (NH) and subsequent stenosis. It is found that the stenosis, prior to a surgical intervention, restores the normal physiological WSS in the vein. As a result, this investigation provides evidence that the adaptation principle, known to apply in the arterial system, is also valid in the venous system. A novel graphical method is developed that combines clinical and computational data to assist in interpreting these physiological mechanisms including adaptation that lead to changes in vein geometry over time. [ABSTRACT FROM AUTHOR]

A new axisymmetric level-set code for incompressible, multiphase flows using the vorticity-streamfunction formulation has been developed. The level-set method is well suited to treating multiphase flows having complex interface shapes that may undergo topological changes, such as merging and splitting of bubbles. The initial acceleration of a single air bub- ble in water has been analyzed and found to be approximately 3.3g, not 2g, which is the predicted value from an added mass analysis based on potentialflow theory. [ABSTRACT FROM AUTHOR]

Numerical simulations of the unsteady, two-dimensional, incompressible Navier-Stokes equations are performed for a Newtonian fluid in a channel having a symmetric constriction modeled by a two-parameter Gaussian distribution on both channel walls. The Reynolds number based on inlet half-channel height and mean inlet velocity ranges from 1 to 3000. Constriction ratios based on the half-channel height of 0.25, 0.5, and 0.75 are considered. The results show that both the Reynolds number and constriction geometry have a significant effect on the behavior of the post-constriction flow field. The Navier-Stokes solutions are observed to experience a number of bifurcations: steady attached flow, steady separated flow (symmetric and asymmetric), and unsteady vortex shedding downstream of the constriction depending on the Reynolds number and constriction ratio. A sequence of events is described showing how a sustained spatially growing flow instability, reminiscent of a convective instability, leads to the vortex shedding phenomenon via a proposed streamwise pressure-gradient mechanism. [ABSTRACT FROM AUTHOR]

Background: A priority of the National Cancer Institute (NCI) is to acquire, aggregate and integrate cancer control data that facilitates collaborations to address health disparities and communication inequalities. To better communicate cancer research to the public, the NCI developed the Health Information National Trends Survey (HINTS). However, as with most national health surveillance systems, HINTS nationally obtained data are not sufficient to address the behaviors of unique demographic and geographic subpopulations. US Pacific Islanders are one of the fastest growing population groups in the US, and cancer is the leading cause of death in this group. Limited knowledge about the cancer communication practices and risk behaviors of US Pacific Islanders drive the poor implementation of effective cancer prevention interventions. Aim: This study aims to document the prevalence and differences in the cancer relevant knowledge, attitudes, and information seeking practices of Pacific Islander populations residing in Hawaii. Specifically, we aim to expand HINTS assessment to native Hawaiians and recent migrant Marshallese and Chuukese populations in Hawaii. Methods: We conducted surveys with 352 native Hawaiians, 282 Chuukese, and 129 Marshallese residing in HI. We used Respondent Driven Sampling method (RDS) to recruit these geographically diffuse populations in HI. The survey included questions about basic knowledge, attitude and behavior about various cancers, detailed communication behaviors about health information, and cultural beliefs and practices. Results: Data show there are clear differences among the three ethnic groups across a variety of cancer-related attitudes, knowledge, behaviors and risk factors. For example, a larger proportion of Chuukese have BMIs that can be described as obese or morbidly obese compared with native Hawaiians. On the other hand, native Hawaiians are significantly more likely to smoke than Marshallese and Chuukese. These groups also differ significantly regarding the level of acculturation, religiosity, fatalism about cancer, and trust in medical professionals. Regarding communication, cell phone use was common with 75% of native Hawaiians, 80% of Marshallese and 88% of Chuukese having cell phones. This use of cellphone technology was in stark contrast to Internet use with only 45% of native Hawaiians, 49% of Marshallese and 27% of Chuukese reporting access to the Web. Conclusion: There is a need for cancer prevention programs for Pacific Islanders in Hawaii. An effective health program has to address their unique cultural beliefs and practices, and fit their unique communication ecology. This study provides new knowledge concerning the use of nonprobability based study sampling methods, and the role of culture in cancer-related communications in influencing cancer risk behaviors that may be generalizable to the growing number of migrant Pacific Islander populations living in the US. [ABSTRACT FROM AUTHOR]

Background: Culture is an important force which affects health behaviors linked to cancer risks among immigrants. Studies have demonstrated the process of acculturation can produce a form of stress that impact health negatively. On the other hand, research suggests that biculturalism, defined as the combining and practicing of customs from two cultures, may be a healthy approach to acculturation. Biculturalism is especially relevant for youth immigrants as their cultural identities are still developing. Pacific Islanders, a fastest growing populations in the US, often experience discrimination in the society at large and in the health care system. Pacific Islander youth in the US navigate between two cultural identities: their native culture as they live in a close-knit community that still maintains strong cultural norms and values, and the dominant American culture that they face once they step outside their community. This is one of the rare studies that examine the relationship between acculturation and cancer preventive behaviors among Pacific Islander youth. Aim: We aim to study the process through which biculturalism influences cancer risk and preventive behaviors such as smoking, sunscreen applications, physical activity and healthy eating among Pacific Islander youth immigrants in Hawaii. Specifically, we map the process of influence that links biculturalism to self-esteem and to these cancer risk and preventive behaviors. Methods: Using survey data from 284 Pacific Islander youth, we developed and tested a theoretically driven model that specifies the relationship among variables listed above. Results: Results show that self-esteem serves as an important mediator connecting biculturalism to cancer preventive behaviors. While biculturalism did not have a direct influence on behaviors and outcomes, it led to increased self-esteem which, in turn, directly influenced attitudes about sunscreen application, physical activity and healthy eating. However, there was neither direct nor indirect link between biculturalism and smoking. Conclusion: While numerous studies have shown links between biculturalism and health, not many studies focus on the specific process through which the influence is exerted. This study provides an important insight into the process through which biculturalism impacts cancer preventive behaviors among minority youth in America. Data from the study showed a clear relationship between biculturalism, self-esteem, their attitudes and behavior related to cancer prevention among Pacific Islander youth living in Hawaii. This study provides insights into potentially novel methods and interventions designed to increase cancer preventive behaviors among migrant youth by dually promoting adoption of U.S. cultural norms, while concurrently embracing an individual´s historic cultural identity. [ABSTRACT FROM AUTHOR]