P/2010A2 LINEAR - I: An impact in the Asteroid Main Belt

Comet P/2010A2 LINEAR is a good candidate for membership with the Main Belt Comet family. It was observed with several telescopes (ESO NTT, La Silla; Gemini North, Mauna Kea; UH 2.2m, Mauna Kea) from 14 Jan. until 19 Feb. 2010 in order to characterize and monitor it and its very unusual dust tail, which appears almost fully detached from the nucleus; the head of the tail includes two narrow arcs forming a cross. The immediate surroundings of the nucleus were found dust-free, which allowed an estimate of the nucleus radius of 80-90m. A model of the thermal evolution indicates that such a small nucleus could not maintain any ice content for more than a few million years on its current orbit, ruling out ice sublimation dust ejection mechanism. Rotational spin-up and electrostatic dust levitations were also rejected, leaving an impact with a smaller body as the favoured hypothesis, and ruling out the cometary nature of the object. The impact is further supported by the analysis of the tail structure. Finston-Probstein dynamical dust modelling indicates the tail was produced by a single burst of dust emission. More advanced models, independently indicate that this burst populated a hollow cone with a half-opening angle alpha~40degr and with an ejection velocity v_max ~ 0.2m/s, where the small dust grains fill the observed tail, while the arcs are foreshortened sections of the burst cone. The dust grains in the tail are measured to have radii between a=1-20mm, with a differential size distribution proportional to a^(-3.44 +/- 0.08). The dust contained in the tail is estimated to at least 8x10^8kg, which would form a sphere of 40m radius. Analysing these results in the framework of crater physics, we conclude that a gravity-controlled crater would have grown up to ~100m radius, i.e. comparable to the size of the body. The non-disruption of the body suggest this was an oblique impact.Comment: 15 pages, 11 figures, in pres

Recruitment of racial/ethnic minority older adults through community sites for focus group discussions

Abstract Background Despite a body of evidence on racial/ethnic minority enrollment and retention in research, literature specifically focused on recruiting racially/ethnically diverse older adults for social science studies is limited. There is a need for more rigorous research on methodological issues and the efficacy of recruitment methods. Cultural obstacles to recruitment of racial/ethnic minority older adults include language barriers, lack of cultural sensitivity of target communities on the part of researchers, and culturally inappropriate assessment tools. Methods Guided by the Consolidated Framework for Implementation Research (CFIR), this study critically appraised the recruitment of racial/ethnic minority older adults for focus groups. The initial approach involved using the physical and social infrastructure of the ElderSmile network, a community-based initiative to promote oral and general health and conduct health screenings in places where older adults gather, to recruit racial/ethnic minority adults for a social science component of an interdisciplinary initiative. The process involved planning a recruitment strategy, engaging the individuals involved in its implementation (opinion leaders in senior centers, program staff as implementation leaders, senior community-based colleagues as champions, and motivated center directors as change agents), executing the recruitment plan, and reflecting on the process of implementation. Results While the recruitment phase of the study was delayed by 6 months to allow for ongoing recruitment and filling of focus group slots, the flexibility of the recruitment plan, the expertise of the research team members, the perseverance of the recruitment staff, and the cultivation of change agents ultimately resulted in meeting the study targets for enrollment in terms of both numbers of focus group discussions (n = 24) and numbers of participants (n = 194). Conclusions This study adds to the literature in two important ways. First, we leveraged the social and physical infrastructure of an existing program to recruit participants through community sites where older adults gather. Second, we used the CFIR to guide the appraisal of the recruitment process, which underscored important considerations for both reaching and engaging this underserved population. This was especially true in terms of understanding the disparate roles of the individuals involved in implementing and facilitating the recruitment plan

Peroxiredoxin-4 and dopamine D5 receptor interact to reduce oxidative stress and inflammation in the kidney

AIMS: Reactive oxygen species are highly reactive molecules generated in different subcellular compartments. Both the dopamine D5 receptor (D5R) and endoplasmic reticulum-resident peroxiredoxin-4 (PRDX4) play protective roles against oxidative stress. This study is aimed at investigating the interaction between PRDX4 and D5R in regulating oxidative stress in the kidney. RESULTS: Fenoldopam (FEN), a D1R and D5R agonist, increased PRDX4 protein expression, mainly in non-lipid rafts, in D5R-HEK 293 cells. FEN increased the co-immunoprecipitation of D5R and PRDX4 and their colocalization, particularly in the endoplasmic reticulum. The efficiency of Förster resonance energy transfer was increased with FEN treatment measured with fluorescence lifetime imaging microscopy. Silencing of PRDX4 increased hydrogen peroxide production, impaired the inhibitory effect of FEN on hydrogen peroxide production, and increased the production of interleukin-1, tumor necrosis factor, and caspase-12 in renal cells. Furthermore, in Drd5-/- mice, which are in a state of oxidative stress, renal cortical PRDX4 was decreased whereas interleukin-1 , tumor necrosis factor, and caspase-12 were increased, relative to their normotensive wild-type Drd5+/+ littermates. INNOVATION: Our findings demonstrate a novel relationship between D5R and PRDX4 and the consequent effects of this relationship in attenuating hydrogen peroxide production in the endoplasmic reticulum and the production of proinflammatory cytokines. This study provides the potential for the development of biomarkers and new therapeutics for renal inflammatory disorders, including hypertension. CONCLUSION: PRDX4 interacts with D5R to decrease oxidative stress and inflammation in renal cells which may have potential of translational significance