2,099 research outputs found

    Sugar Derivatives in Residues Produced from the UV Irradiation of Astrophysical Ice Analogs

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    A large variety of organic compounds of astrobiological and prebiotic interest have been detected in carbonaceous meteorites. These include amino acids, carboxylic acids, amphiphiles, functionalized nitrogen heterocycles such as nucleobases, functionalized polycylic aromatic hydrocarbons such as quinones, and sugar derivatives. The sugar derivatives identified in the Murchison and Murray meteorites are mainly sugar alcohols and sugar acids, and only the smallest sugar (dihydroxyacetone) has been detected. The presence of such a variety of organics in meteorites strongly suggests that molecules essential to life can form abiotically under astrophysical conditions. This hypothesis is further supported by laboratory studies in which astrophysical ice analogs (mixtures of H2O, CO, CO2, CH3OH, CH4, NH3, etc.) are subjected to ultraviolet (UV) irradiation at low temperature (<15 K) to simulate cold interstellar environments. These studies show that the organic residues recovered at room temperature after irradiation contain amino acids, amphiphiles, nucleobases, sugar derivatives, as well as other complex organic compounds. The finding of such compounds under plausible interstellar conditions is consistent with the presence of organic compounds in meteorites. Until very recently, no systematic search for the presence of sugar derivatives in laboratory residues had been carried out. The detection of ribose, the sugar constituent of RNA in all living systems, as well as other sugars, sugar alcohols, and sugar acids have been recently reported in one organic residue produced from the UV irradiation of an H2O:CH3OH:NH3 (10:3.5:1) ice mixture at 80 K. In this work, we present a detailed study of organic residues produced from the UV irradiation ice mixtures of several starting compositions (containing H2O, CH3OH, CO, CO2, and/or NH3) at <15 K for their sugar derivative content. Our results confirm the presence of all 3C5C sugar alcohols, several 3C5C sugars, and all 3C4C sugar acids (in decreasing order of abundances) in the residues. The higher abundances of sugar alcohols in these residues suggest a pathway in which sugar alcohols are formed first, while the formation of sugars and sugar acids require more steps. Finally, our results are compared with the detection of sugars derivatives in primitive meteorites

    Predictors of subgroups based on maximum drinks per occasion over six years for 833 adolescents and young adults in COGA.

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    ObjectiveA person's pattern of heavier drinking often changes over time, especially during the early drinking years, and reflects complex relationships among a wide range of characteristics. Optimal understanding of the predictors of drinking during times of change might come from studies of trajectories of alcohol intake rather than cross-sectional evaluations.MethodThe patterns of maximum drinks per occasion were evaluated every 2 years between the average ages of 18 and 24 years for 833 subjects from the Collaborative Study on the Genetics of Alcoholism. Latent class growth analysis identified latent classes for the trajectories of maximum drinks, and then logistic regression analyses highlighted variables that best predicted class membership.ResultsFour latent classes were found, including Class 1 (69%), with about 5 maximum drinks per occasion across time; Class 2 (15%), with about 9 drinks at baseline that increased to 18 across time; Class 3 (10%), who began with a maximum of 18 drinks per occasion but decreased to 9 over time; and Class 4 (6%), with a maximum of about 22 drinks across time. The most consistent predictors of higher drinking classes were female sex, a low baseline level of response to alcohol, externalizing characteristics, prior alcohol and tobacco use, and heavier drinking peers.ConclusionsFour trajectory classes were observed and were best predicted by a combination of items that reflected demography, substance use, level of response and externalizing phenotypes, and baseline environment and attitudes

    The Dipole Anisotropy of the 2mass Redshift Survey

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    We estimate the flux weighted acceleration on the Local Group (LG) from the near-infrared Two Micron All Sky Redshift Survey (2MRS). The near-infrared flux weighted dipoles are very robust because they closely approximate a mass weighted dipole, bypassing the effects of redshift distortions and require no preferred reference frame. We use this method with the redshift information to determine the change in dipole with distance. The LG dipole seemingly converges by 60 Mpc/h. Assuming convergence, the comparison of the 2MRS flux dipole and the CMB dipole provides a value for the combination of the mass density and luminosity bias parameters Omega_m^0.6/b_L= 0.40+/-0.09.Comment: 4 pages, 2 figures, Contribution to Rencontres de Moriond: Contents and Structures of the Universe, March 18-25, 2006, La Thuil

    Governance of Arctic Marine Shipping

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    The governance of shipping activities in the Arctic might be described as a complicated mosaic The 1982 United Nations Convention on the Law of the Sea UNCLOS often referred to as the constitution of the oceans sets out the overall legal framework for the regulation of shipping The Convention sets out coastal state legislative and enforcement powers over foreign ships according to the maritime zones of jurisdiction laid out in the Convention A fragmented array of international agreements attempts to address specific challenges raised by shipping such as marine pollution prevention standards ship safety seafarer rights and qualifications and liability and compensation for spills Appendix A In addition the threats raised toby ships operating in icecovered waters have led northern countries that border these waters such as Canada and Russia to adopt national legislation specifically for Arctic shipping Appendix

    On the Origin of the Treponematoses: A Phylogenetic Approach

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    For 500 years, controversy has raged around the origin of T. pallidum subsp. pallidum, the bacterium responsible for syphilis. Did Christopher Columbus and his men introduce this pathogen into Renaissance Europe, after contracting it during their voyage to the New World? Or does syphilis have a much older history in the Old World? This paper represents the first attempt to use a phylogenetic approach to solve this question. In addition, it clarifies the evolutionary relationships between the pathogen that causes syphilis and the other T. pallidum subspecies, which cause the neglected tropical diseases yaws and endemic syphilis. Using a collection of pathogenic Treponema strains that is unprecedented in size, we show that yaws appears to be an ancient infection in humans while venereal syphilis arose relatively recently in human history. In addition, the closest relatives of syphilis-causing strains identified in this study were found in South America, providing support for the Columbian theory of syphilis's origin

    Intergenerational social mobility and mid-life status attainment: influences of childhood intelligence, childhood social factors, and education

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    We examined the influences of childhood social background, childhood cognitive ability, and education on intergenerational social mobility and social status attainment at midlife. The subjects were men born in 1921 and who participated in the Scottish Mental Survey of 1932 and thereafter in the Midspan Collaborative study in Scotland between 1970 and 1973. In logistic regression analyses, childhood cognitive ability and height were associated with upward and downward change from father's social class to participant's social class at mid-life. Education significantly influenced upward social mobility. Number of siblings had no significant effect on social mobility. These effects were also examined after adjusting for the other variables. In structural equation modelling analyses, father's social class and childhood cognitive ability influenced social status attainment at midlife, with education and occupational status in young adulthood as partially mediating factors. It was noteworthy that childhood cognitive ability related more strongly to occupation in midlife than to first occupation. These data add to the relatively few studies that track the process of status attainment in adulthood, they provide information from a new geographical setting, and they contain information from a greater proportion of the lifecourse than do most existing studies

    Effectiveness of Rituximab for the Treatment of Rheumatoid Arthritis in Patients with Prior Exposure to Anti-TNF: Results from the CORRONA Registry

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    OBJECTIVE: To characterize the real-world effectiveness of rituximab (RTX) in patients with rheumatoid arthritis. METHODS: Clinical effectiveness at 12 months was assessed in patients who were prescribed RTX based on the Clinical Disease Activity Index (CDAI). Change in CDAI was calculated (CDAI at 12 mos minus at initiation). Achievement of remission or low disease activity (LDA; CDAI \u3c /= 10) among those with moderate/high disease activity at the time of RTX initiation was compared based on prior anti-tumor necrosis factor agent (anti-TNF) use (1 vs \u3e /= 2) using logistic regression models. RESULTS: Patients (n = 265) were followed for 12 months with a mean change in CDAI of -8.1 (95% CI -9.8 - -6.4). Of the 218 patients with moderate/high disease activity at baseline, patients with 1 prior anti-TNF (baseline CDAI 25.0) demonstrated a mean change in CDAI of -10.1 (95% CI -13.2 - -7.0); patients with \u3e /= 2 prior anti-TNF (baseline CDAI 30.0) demonstrated a mean change of -10.5 (95% CI -12.9 - -8.0). The unadjusted OR for achieving LDA/remission in patients with moderate/high disease activity at baseline exposed to \u3e /= 2 versus 1 prior anti-TNF was 0.40 (95% CI 0.22-0.73), which was robust to 4 different adjusted models (OR range 0.38-0.44). CONCLUSION: A good clinical response was observed in all patients; however, patients previously treated with 1 anti-TNF, who had lower baseline CDAI and a greater opportunity for clinical improvement compared with patients previously treated with \u3e /= 2 anti-TNF, were more likely to achieve LDA/remission

    Sustainability appraisal: Jack of all trades, master of none?

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    Sustainable development is a commonly quoted goal for decision making and supports a large number of other discourses. Sustainability appraisal has a stated goal of supporting decision making for sustainable development. We suggest that the inherent flexibility of sustainability appraisal facilitates outcomes that often do not adhere to the three goals enshrined in most definitions of sustainable development: economic growth, environmental protection and enhancement, and the wellbeing of the human population. Current practice is for sustainable development to be disenfranchised through the interpretation of sustainability, whereby the best alternative is good enough even when unsustainable. Practitioners must carefully and transparently review the frameworks applied during sustainability appraisal to ensure that outcomes will meet the three goals, rather than focusing on a discourse that emphasises one or more goals at the expense of the other(s)

    Governance of Arctic Marine Shipping

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    The governance of shipping activities in the Arctic might be described as a “complicated mosaic.” The 1982 United Nations Convention on the Law of the Sea (UNCLOS), often referred to as the constitution of the oceans, sets out the overall legal framework for the regulation of shipping. The Convention sets out coastal state legislative and enforcement powers over foreign ships according to the maritime zones of jurisdiction laid out in the Convention. A fragmented array of international agreements attempts to address specific challenges raised by shipping such as marine pollution prevention standards, ship safety, seafarer rights and qualifications, and liability and compensation for spills (Appendix A). In addition, the threats raised to/by ships operating in ice-covered waters have led northern countries that border these waters, such as Canada and Russia, to adopt national legislation specifically for Arctic shipping (Appendix B)

    Clinical and demographic factors associated with change and maintenance of disease severity in a large registry of patients with rheumatoid arthritis

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    BACKGROUND: We examined models to predict disease activity transitions from moderate to low or severe and associated factors in patients with rheumatoid arthritis (RA). METHODS: Data from RA patients enrolled in the Corrona registry (October 2001 to August 2014) were analyzed. Clinical Disease Activity Index (CDAI) definitions were used for low ( \u3c /=10), moderate ( \u3e 10 and \u3c /=22), and severe ( \u3e 22) disease activity states. A Markov model for repeated measures allowing for covariate dependence was used to model transitions between three (low, moderate, severe) states and estimate population transition probabilities. Mean sojourn times were calculated to compare length of time in particular states. Logistic regression models were used to examine impacts of covariates (time between visits, chronological year, disease duration, age) on disease states. RESULTS: Data from 29,853 patients (251,375 visits) and a sub-cohort of 9812 patients (46,534 visits) with regular visits (every 3-9 months) were analyzed. The probability of moving from moderate to low or severe disease by next visit was 47% and 18%, respectively. Patients stayed in moderate disease for mean 4.25 months (95% confidence interval: 4.18-4.32). Transition probabilities showed 20% of patients with low disease activity moved to moderate or severe disease within 6 months; \u3e 35% of patients with moderate disease remained in moderate disease after 6 months. Results were similar for the regular-visit sub-cohort. Significant interactions with prior disease state were seen with chronological year and disease duration. CONCLUSION: A substantial proportion of patients remain in moderate disease, emphasizing the need for treat-to-target strategies for RA patients
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