226 research outputs found
Large-scale collective motion of RFGC galaxies
We processed the data about radial velocities and HI linewidths for 1678 flat
edge-on spirals from the Revised Flat Galaxy Catalogue. We obtained the
parameters of the multipole components of large-scale velocity field of
collective non-Hubble galaxy motion as well as the parameters of the
generalized Tully-Fisher relationship in the "HI line width - linear diameter"
version. All the calculations were performed independently in the framework of
three models, where the multipole decomposition of the galaxy velocity field
was limited to a dipole, quadrupole and octopole terms respectively. We showed
that both the quadrupole and the octopole components are statistically
significant.
On the basis of the compiled list of peculiar velocities of 1623 galaxies we
obtained the estimations of cosmological parameters Omega_m and sigma_8. This
estimation is obtained in both graphical form and as a constraint of the value
S_8=sigma_8(Omega_m/0.3)^0.35 = 0.91 +/- 0.05.Comment: Accepted for publication in Astrophysics and Space Scienc
Extrusion limits of magnesium alloys
Magnesium alloys are generally found to be slower to extrude than aluminum alloys; however, limited quantitative comparisons of the actual operating windows have been published. In this work, the extrusion limits are determined for a series of commercial magnesium alloys (M1, ZM21, AZ31, AZ61, and ZK60). These are compared with the limits established for aluminum alloy AA6063. The maximum extrusion speed of alloy M1 is shown to be similar to AA6063. Alloys ZM21, AZ31, ZK60, and AZ61 exhibit maximum extrusion speeds 44, 18, 4, and 3 pct, respectively, of the maximum measured for AA6063. For AZ31, the maximum extrusion speed is increased by 22 pct after homogenization and by 64 pct for repeat extrusions. The variation in the extrusion limits with changing alloy content is rationalized in terms of differences in the hot working flow stress and solidus temperature.<br /
CD36 promotes vasculogenic mimicry in melanoma by mediating adhesion to the extracellular matrix
Background: The formation of blood vessels within solid tumors directly contributes to cancer growth and metastasis. Until recently, tumor vasculature was thought to occur exclusively via endothelial cell (EC) lined structures (i.e. angiogenesis), but a second source of tumor vasculature arises from the cancer cells themselves, a process known as vasculogenic mimicry (VM). While it is generally understood that the function of VM vessels is the same as that of EC-lined vessels (i.e. to supply oxygen and nutrients to the proliferating cancer cells), the molecular mechanisms underpinning VM are yet to be fully elucidated. Methods: Human VM-competent melanoma cell lines were examined for their VM potential using the in vitro angiogenesis assays (Matrigel), together with inhibition studies using small interfering RNA and blocking monoclonal antibodies. Invasion assays and adhesion assays were used to examine cancer cell function. Results: Herein we demonstrate that CD36, a cell surface glycoprotein known to promote angiogenesis by ECs, also supports VM formation by human melanoma cancer cells. In silico analysis of CD36 expression within the melanoma cohort of The Cancer Genome Atlas suggests that melanoma patients with high expression of CD36 have a poorer clinical outcome. Using in vitro ‘angiogenesis’ assays and CD36-knockdown approaches, we reveal that CD36 supports VM formation by human melanoma cells as well as adhesion to, and invasion through, a cancer derived extracellular matrix substrate. Interestingly, thrombospondin-1 (TSP-1), a ligand for CD36 on ECs that inhibits angiogenesis, has no effect on VM formation. Further investigation revealed a role for laminin, but not collagen or fibronectin, as ligands for CD36 expressing melanoma cells. Conclusions: Taken together, this study suggests that CD36 is a novel regulator of VM by melanoma cancer cells that is facilitated, at least in part, via integrin-α3 and laminin. Unlike angiogenesis, VM is not perturbed by the presence of TSP-1, thus providing new information on differences between these two processes of tumor vascularization which may be exploited to combat cancer progression.Carmela Martini, Mark DeNichilo, Danielle P. King, Michaelia P. Cockshell, Brenton Ebert, Brian Dale, Lisa M. Ebert, Anthony Woods, and Claudine S. Bonde
Resilience and HIV: a review of the definition and study of resilience
We use a socioecological model of health to define resilience, review the definition and study of resilience among persons living with human immunodeficiency virus (PLWH) in the existing peer-reviewed literature, and discuss the strengths and limitations of how resilience is defined and studied in HIV research. We conducted a review of resilience research for HIV-related behaviors/outcomes of antiretroviral therapy (ART) adherence, clinic attendance, CD4 cell count, viral load, viral suppression, and/or immune functioning among PLWH. We performed searches using PubMed, PsycINFO and Google Scholar databases. The initial search generated 14,296 articles across the three databases, but based on our screening of these articles and inclusion criteria, n = 54 articles were included for review. The majority of HIV resilience research defines resilience only at the individual (i.e., psychological) level or studies individual and limited interpersonal resilience (e.g., social support). Furthermore, the preponderance of HIV resilience research uses general measures of resilience; these measures have not been developed with or tailored to the needs of PLWH. Our review suggests that a socioecological model of health approach can more fully represent the construct of resilience. Furthermore, measures specific to PLWH that capture individual, interpersonal, and neighborhood resilience are needed
Area-selective electrodeposition of micro islands for CuInSe2-based photovoltaics
For mass fabrication of highly-efficient photovoltaic modules based on Cu(In,Ga)Se 2 (CIGSe) absorber layers the availability and cost of the critical raw materials In and Ga present a potential bottleneck. The micro-concentrator solar cell concept provides a solution by using micro lenses to concentrate incoming sun light on an array of micro-sized CIGSe solar cells. The challenge is to fabricate CIGSe micro islands in exactly the desired positions using only the required material. Here, we analyze the area-selective electrodeposition of CuInSe 2 into holes in an insulating SiO 2 template layer as a material-efficient fabrication approach. We observe that the deposition process shows a strong dependence on the hole size, with a faster deposition around the hole perimeter. Based on a model developed for electrochemical reactions at ultra-micro electrodes, we develop numerical simulations for the electrochemical deposition process. The simulations consider the changing micro-electrode geometry throughout the deposition process, and provide a reasonable fit to the experimental data. Finally, it is shown that CuInSe 2 micro solar cells fabricated by electrodeposition reach efficiencies of 4.8% under 1 sun, providing a proof-of-concept demonstration meriting further development
Development of Long and Short Forms of the Multilevel Resilience Resource Measure for African American/Black Adults Living with HIV
Understanding resilience in relation to HIV-related outcomes may help address racial/ethnic disparities, however, significant gaps in its measurement preclude in-depth study. Thus, this research aims to develop and evaluate the psychometric properties of long and short forms of the Multilevel Resilience Resource Measure for African American/Black Adults Living with HIV. To develop the items, we conducted a mixed methods study (N = 48) and reviewed published resilience measures. We completed content validity index analyses to ensure the items reflected the resilience construct. Next, we conducted 20 cognitive interviews and a field survey (N = 400). The long and short forms demonstrated acceptable to excellent psychometric properties based on factorial validity, internal consistency and convergent validity and on measurement invariance (conducted for the short form only). These measures provide a comprehensive framework to examine resilience and HIV-related outcomes and can inform resilience-building interventions to reduce racial and ethnic health disparities
Multilevel Resilience and HIV Virologic Suppression Among African American/Black Adults in the Southeastern United States
Objective: To assess overall and by neighborhood risk environments whether multilevel resilience resources were associated with HIV virologic suppression among African American/Black adults in the Southeastern United States. Setting and Methods: This clinical cohort sub-study included 436 African American/Black participants enrolled in two parent HIV clinical cohorts. Resilience was assessed using the Multilevel Resilience Resource Measure (MRM) for African American/Black adults living with HIV, where endorsement of a MRM statement indicated agreement that a resilience resource helped a participant continue HIV care despite challenges or was present in a participant’s neighborhood. Modified Poisson regression models estimated adjusted prevalence ratios (aPRs) for virologic suppression as a function of categorical MRM scores, controlling for demographic, clinical, and behavioral characteristics at or prior to sub-study enrollment. We assessed for effect measure modification (EMM) by neighborhood risk environments. Results: Compared to participants with lesser endorsement of multilevel resilience resources, aPRs for virologic suppression among those with greater or moderate endorsement were 1.03 (95% confidence interval: 0.96–1.11) and 1.03 (0.96–1.11), respectively. Regarding multilevel resilience resource endorsement, there was no strong evidence for EMM by levels of neighborhood risk environments. Conclusions: Modest positive associations between higher multilevel resilience resource endorsement and virologic suppression were at times most compatible with the data. However, null findings were also compatible. There was no strong evidence for EMM concerning multilevel resilience resource endorsement, which could have been due to random error. Prospective studies assessing EMM by levels of the neighborhood risk environment with larger sample sizes are needed
Effect of flooding on survival and initial growth of Ocotea pulchella (Nees) Mez. seedlings in semi-controlled light conditions
Sociocultural considerations in aging men's health: implications and recommendations for the clinician
http://dx.doi.org/10.1016/j.jomh.2009.07.00
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