25 research outputs found

    Evidence for Two Populations of Classical Transneptunian Objects: The Strong Inclination Dependence of Classical Binaries

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    We have searched 101 Classical transneptunian objects for companions with the Hubble Space Telescope. Of these, at least 21 are binary. The heliocentric inclinations of the objects we observed range from 0.6-34 degrees. We find a very strong anticorrelation of binaries with inclination. Of the 58 targets that have inclinations of less than 5.5 degrees, 17 are binary, a binary fraction of 29 +7/-6%. All 17 are similar-brightness systems. On the contrary, only 4 of the 42 objects with inclinations greater than 5.5 degrees have satellites and only 1 of these is a similar-brightness binary. This striking dichotomy appears to agree with other indications that the low eccentricity, non-resonant Classical transneptunian objects include two overlapping populations with significantly different physical properties and dynamical histories.Comment: 32 pages, 4 figures, 2 tables in press for Icarus volume 194 Note added in proof and reference updates in this corrected versio

    TNOs are Cool: A survey of the trans-Neptunian region V. Physical characterization of 18 Plutinos using Herschel PACS observations

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    We present Herschel PACS photometry of 18 Plutinos and determine sizes and albedos for these objects using thermal modeling. We analyze our results for correlations, draw conclusions on the Plutino size distribution, and compare to earlier results. Flux densities are derived from PACS mini scan-maps using specialized data reduction and photometry methods. In order to improve the quality of our results, we combine our PACS data with existing Spitzer MIPS data where possible, and refine existing absolute magnitudes for the targets. The physical characterization of our sample is done using a thermal model. Uncertainties of the physical parameters are derived using customized Monte Carlo methods. The correlation analysis is performed using a bootstrap Spearman rank analysis. We find the sizes of our Plutinos to range from 150 to 730 km and geometric albedos to vary between 0.04 and 0.28. The average albedo of the sample is 0.08 \pm 0.03, which is comparable to the mean albedo of Centaurs, Jupiter Family comets and other Trans-Neptunian Objects. We were able to calibrate the Plutino size scale for the first time and find the cumulative Plutino size distribution to be best fit using a cumulative power law with q = 2 at sizes ranging from 120-400 km and q = 3 at larger sizes. We revise the bulk density of 1999 TC36 and find a density of 0.64 (+0.15/-0.11) g cm-3. On the basis of a modified Spearman rank analysis technique our Plutino sample appears to be biased with respect to object size but unbiased with respect to albedo. Furthermore, we find biases based on geometrical aspects and color in our sample. There is qualitative evidence that icy Plutinos have higher albedos than the average of the sample.Comment: 18 pages, 8 figures, 8 tables, accepted for publication in A&

    Minimum Wage Channels of Adjustment

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    Industrial Relations, forthcoming Abstract: The effects of minimum wage increases in 2007-2009 are analyzed using a sample of restaurants from Georgia/Alabama. Store-level payroll records provide precise measures of compliance costs. Examined are multiple adjustment channels. Exploiting variation in compliance costs across restaurants, we find employment and hours responses to be variable and in most cases statistically insignificant. Channels of adjustment to wage increases and to changes in non-labor costs include prices, profits, wage compression, turnover, and performance standards

    Efficacies of plant phenolic compounds on sodium butyrate induced anti-tumour activity

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    861-864The ability of the differentiation inducing agent sodium butyrate (NaB) alone or combined with plant -derived phenolic compounds to produce growth inhibition in human erythroleukemic cells was investigated. As a single agent,curcumin produced a marked inhibition of proliferation indicated by its low concentration used. The effect of phenolics on the cell cycle could probably contribute to the augmented antiproliferative activity of NaB. The present data show that quercetin produced synergistic effect in terms of cell killing in association with NaB. Both curcumin and ferulic acid potentiated NaB induced reduction of cell number. When NaB was added before exposure to graded doses of quercetin it did induce a greater inhibitory effect. The combination of NaB and quercetin seems less effective on S180 ascites tumour cells. As a single agent quercetin was found to be the most efficacious on S180 tumour model

    Global monitoring of the impact of the COVID-19 pandemic through online surveys sampled from the Facebook user base

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    Simultaneously tracking the global impact of COVID-19 is challenging because of regional variation in resources and reporting. Leveraging self-reported survey outcomes via an existing international social media network has the potential to provide standardized data streams to support monitoring and decision-making worldwide, in real time, and with limited local resources. The University of Maryland Global COVID-19 Trends and Impact Survey (UMD-CTIS), in partnership with Facebook, has invited daily cross-sectional samples from the social media platform's active users to participate in the survey since its launch on April 23, 2020. We analyzed UMD-CTIS survey data through December 20, 2020, from 31,142,582 responses representing 114 countries/territories weighted for nonresponse and adjusted to basic demographics. We show consistent respondent demographics over time for many countries/territories. Machine Learning models trained on national and pooled global data verified known symptom indicators. COVID-like illness (CLI) signals were correlated with government benchmark data. Importantly, the best benchmarked UMD-CTIS signal uses a single survey item whereby respondents report on CLI in their local community. In regions with strained health infrastructure but active social media users, we show it is possible to define COVID-19 impact trajectories using a remote platform independent of local government resources. This syndromic surveillance public health tool is the largest global health survey to date and, with brief participant engagement, can provide meaningful, timely insights into the global COVID-19 pandemic at a local scale
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