1,086 research outputs found

    High energy scattering in 2+1 QCD

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    High energy scattering in 2+1 QCD is studied using the recent approach of Verlinde and Verlinde. We calculate the color singlet part of the quark-quark scattering exactly within this approach, and discuss some physical implication of this result. We also demonstrate, by two independent methods, that reggeization fails for the color singlet channel. We briefly comment on the problem in 3+1 QCD.Comment: 20 pages, references adde

    Primary production of the central grassland region of the United States

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    Includes bibliographical references (pages 44-45).Aboveground net primary production of grasslands is strongly influenced by the amount and distribution of annual precipitation. Analysis of data collected at 9500 sites throughout the central United States confirmed the overwhelming importance of water availability as a control of production. The regional spatial pattern of production reflected the east-west gradient in annual precipitation. Lowest values of aboveground net primary production were observed in the west and highest values in the east. This spatial pattern was shifted eastward during unfavorable years and westward during favorable years. Variability in production among years was maximum in northern New Mexico and southwestern Kansas and decreased towards the north and south. The regional pattern of production was largely accounted for by annual precipitation. Production at the site level was explained by annual precipitation, soil water-holding capacity, and an interaction term. Our results support the inverse texture hypothesis. When precipitation is 370 mm/yr

    Rab17, a novel small GTPase, is specific for epithelial cells and is induced during cell polarization

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    The rab subfamily of small GTPases has been demonstrated to play an important role in the regulation of membrane traffic in eukaryotic cells. Compared with nonpolarized cells, epithelial cells have distinct apical and basolateral transport pathways which need to be separately regulated. This raises the question whether epithelial cells require specific rab proteins. However, all rab proteins identified so far were found to be equally expressed in polarized and nonpolarized cells. Here we report the identification of rab17, the first epithelial cell-specific small GTPase. Northern blot analysis on various mouse organs revealed that the rab17 mRNA is present in kidney, liver, and intestine but not in organs lacking epithelial cells nor in fibroblasts. To determine whether rab17 is specific for epithelial cells we studied its expression in the developing kidney. We found that rab17 is absent from the mesenchymal precursors but is induced upon their differentiation into epithelial cells. In situ hybridization studies on the embryonic kidney and intestine revealed that rab17 is restricted to epithelial cells. By immunofluorescence and immunoelectron microscopy on kidney sections, rab17 was localized to the basolateral plasma membrane and to apical tubules. Rab proteins associated with two distinct compartments have been found to regulate transport between them. Therefore, our data suggest that rab17 might be involved in transcellular transport

    Cross-biome transplants of plant litter show decomposition models extend to a broader climatic range but lose predictability at the decadal time scale

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    We analyzed results from 10-year long field incubations of foliar and fine root litter from the Long-term Intersite Decomposition Experiment Team (LIDET) study. We tested whether a variety of climate and litter quality variables could be used to develop regression models of decomposition parameters across wide ranges in litter quality and climate and whether these models changed over short to long time periods. Six genera of foliar and three genera of root litters were studied with a 10-fold range in the ratio of acid unhydrolyzable fraction (AUF, or ‘lignin’) to N. Litter was incubated at 27 field sites across numerous terrestrial biomes including arctic and alpine tundra, temperate and tropical forests, grasslands and warm deserts. We used three separate mathematical models of first-order (exponential) decomposition, emphasizing either the first year or the entire decade. One model included the proportion of relatively stable material as an asymptote. For short-term (first-year) decomposition, nonlinear regressions of exponential or power function form were obtained with r 2 values of 0.82 and 0.64 for foliar and fine-root litter, respectively, across all biomes included. AUF and AUF : N ratio were the most explanative litter quality variables, while the combined temperature-moisture terms AET (actual evapotranspiration) and CDI (climatic decomposition index) were best for climatic effects. Regressions contained some systematic bias for grasslands and arctic and boreal sites, but not for humid tropical forests or temperate deciduous and coniferous forests. The ability of the regression approach to fit climate-driven decomposition models of the 10-year field results was dramatically reduced from the ability to capture drivers of short-term decomposition. Future work will require conceptual and methodological improvements to investigate processes controlling decadal-scale litter decomposition, including the formation of a relatively stable fraction and its subsequent decomposition.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78615/1/j.1365-2486.2009.02086.x.pd

    Factors associated with the decision to investigate child protective services referrals: a systematic review

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    Background: Limited resources for child protection create challenging decision situations for child protective services (CPS) workers at the point of intake. A body of research has examined the factors associated with worker decisions and processes using a variety of methodological approaches to gain knowledge on decision-making. However, few attempts have been made to systematically review this literature. Objective: As part of a larger project on decision-making at intake, this systematic review addressed the question of the factors associated with worker decisions to investigate alleged maltreatment referrals. Methods: Quantitative studies that examined factors associated with screening decisions in CPS practice settings were included in the review. Database and other search methods were used to identify research published in English over a 35-year period (1980-2015). Findings: Of 1,147 identified sources, 18 studies were selected for full data extraction. The studies were conducted in the U.S., Canada, and Sweden and varied in methodological quality. Most studies examined case factors with few studies examining other domains. Conclusions: To inform CPS policy and practice, additional research is needed to examine the relationships between decision-making factors and case outcomes. Greater attention needs to be given to the organizational and external factors that influence decision-making

    Project ATTAIN: Advancing Trauma-Informed Care for Youth with Intellectual and Developmental Disabilities and/or Gender Diverse Youth

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    Children with Intellectual and Developmental Disabilities (IDD) and/or gender diversity are at higher risk of experiencing trauma. Provider knowledge is lacking; trauma, disability, and LGBTQ+ resources are often siloed; and few providers screen for trauma in this population. This paper describes the design, delivery, and initial evaluation of Project ATTAIN (Access to Trauma-informed Treatment and Assessment for Neurodivergent and/or Gender-expansive Youth). ATTAIN is an ongoing 5-year state-wide initiative aiming to assess readiness to engage in new roles and practices over time; provide state-wide training and consultation in trauma, disability, and LGBTQ+-informed practices; install screening and assessment of trauma exposure and PTSD and quality of life into IDD and gender service settings; and include people with lived experience. A readiness assessment identified pre-training gaps between role responsibilities and practice engagement across five professional sectors serving our target population (n=39) in LGBTQ+-, disability-, and trauma-informed practices. We learned that specific sectors would benefit from introductory training to increase buy-in and promote role expansion; others would benefit from advanced instruction and implementation support. So far, we have trained 966 unique providers in trauma-informed care and have seen changes in the attitudes or perspectives of participants. Participants were highly satisfied with our provided training and saw increased knowledge across training. We screened 49 people in an IDD service setting for PTSD and quality of life. Two people with lived experience are active members of our research team, participating in project planning, training delivery, and manuscript authorship. Individuals who work with IDD and/or gender-diverse youth would benefit from increased training to expand their knowledge on LGBTQ+-, disability-, and trauma-informed practices. In year three, we intend to continue outreach and evidence-informed training focused on the intersection of trauma, IDD, and gender diversity. Ongoing evaluation of our outreach, training, and screening efforts will continue to inform program activities

    Cavin-1/PTRF alters prostate cancer cell-derived extracellular vesicle content and internalization to attenuate extracellular vesicle-mediated osteoclastogenesis and osteoblast proliferation

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    Background: Tumour-derived extracellular vesicles (EVs) play a role in tumour progression; however, the spectrum of molecular mechanisms regulating EV secretion and cargo selection remain to be fully elucidated. We have reported that cavin-1 expression in prostate cancer PC3 cells reduced the abundance of a subset of EV proteins, concomitant with reduced xenograft tumour growth and metastasis. Methods: We examined the functional outcomes and mechanisms of cavin-1 expression on PC3-derived EVs (PC3-EVs). Results: PC3-EVs were internalized by osteoclast precursor RAW264.7 cells and primary human osteoblasts (hOBs) in vitro, stimulating osteoclastogenesis 37-fold and hOB proliferation 1.5-fold, respectively. Strikingly, EVs derived from cavin-1-expressing PC3 cells (cavin-1-PC3-EVs) failed to induce multinucleate osteoblasts or hOB proliferation. Cavin-1 was not detected in EVs, indicating an indirect mechanism of action. EV morphology, size and quantity were also not affected by cavin-1 expression, suggesting that cavin-1 modulated EV cargo recruitment rather than release. While cavin-1-EVs had no osteoclastogenic function, they were internalized by RAW264.7 cells but at a reduced efficiency compared to control EVs. EV surface proteins are required for internalization of PC3-EVs by RAW264.7 cells, as proteinase K treatment abolished uptake of both control and cavin-1-PC3-EVs. Removal of sialic acid modifications by neuraminidase treatment increased the amount of control PC3-EVs internalized by RAW264.7 cells, without affecting cavin-1-PC3-EVs. This suggests that cavin-1 expression altered the glycosylation modifications on PC3-EV surface. Finally, cavin-1 expression did not affect EV in vivo tissue targeting as both control and cavin-1-PC3-EVs were predominantly retained in the lung and bone 24 hours after injection into mice. Discussion: Taken together, our results reveal a novel pathway for EV cargo sorting, and highlight the potential of utilizing cavin-1-mediated pathways to attenuate metastatic prostate cancer
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