The Age Evolution of the Radio Morphology of Supernova Remnants

Recent hydrodynamical models of supernova remnants (SNRs) demonstrate that their evolution depends heavily on the inhomogeneities of the surrounding medium. As SNRs expand, their morphologies are influenced by the non-uniform and turbulent structure of their environments, as reflected in their radio continuum emission. In this paper, we measure the asymmetries of 96 SNRs in radio continuum images from three surveys of the Galactic plane and compare these results to the SNRs' radii, which we use as a proxy for their age. We find that larger (older) SNRs are more elliptical/elongated and more mirror asymmetric than smaller (younger) SNRs, though the latter vary in their degrees of asymmetry. This result suggests that SNR shells become more asymmetric as they sweep up the interstellar medium (ISM), as predicted in hydrodynamical models of SNRs expanding in a multi-phase or turbulent ISM.Comment: 16 pages, 5 figures, accepted by ApJ; sample expanded from 22 to 96 source

Ideal ages for family formation among immigrants in Europe

This paper investigates ideal ages for marriage and parenthood among immigrants from over 160 countries origins living in 25 European countries. Ideals regarding the timing of family formation are indicative of how individuals perceive the family life course and provide insight into family-life aspirations and the meaning attached to these transitions. Using data from the European Social Survey (Round 3, 2006; N = 6,330) and a cross-classified multilevel modeling approach, we investigate associations between the influences of the dominant family formation timing patterns in countries of origin and settlement, individual-level characteristics, and ideal ages. We make innovative use of a standard demographic measure, the singulate mean age of marriage, to measure family formation patterns. Results suggests that residential context influences are associated with the timing ideals of all migrants, but origin influences seem to be associated with the ideals of only the most recent migrant

Unconstrained image reconstruction with resolution modelling does not have a unique solution

<b>Background</b>: Social media data is a promising source of social science data. However, deriving the demographic characteristics of users and dealing with the nonrandom, nonrepresentative populations from which they are drawn represent challenges for social scientists. <b>Objective</b>: Given the growing use of social media data in social science research, this paper asks two questions: 1) To what extent are findings obtained with social media data generalizable to broader populations, and 2) what is the best practice for estimating demographic information from Twitter data? <b>Methods</b>: Our analyses use information gathered from 979,992 geo-located Tweets sent by 22,356 unique users in South East England between 23 June and 4 July 2014. We estimate demographic characteristics of the Twitter users with the crowd-sourcing platform CrowdFlower and the image-recognition software Face++. To evaluate bias in the data, we run a series of log-linear models with offsets and calibrate the nonrepresentative sample of Twitter users with mid-year population estimates for South East England. <b>Results</b>: CrowdFlower proves to be more accurate than Face++ for the measurement of age, whereas both tools are highly reliable for measuring the sex of Twitter users. The calibration exercise allows bias correction in the age-, sex-, and location-specific population counts obtained from the Twitter population by augmenting Twitter data with mid-year population estimates. <b>Contribution</b>: The paper proposes best practices for estimating Twitter users' basic demographic characteristics and a calibration method to address the selection bias in the Twitter population, allowing researchers to generalize findings based on Twitter to the general population

Partner choice and timing of first marriage among the children of immigrants in Norway and Sweden

Using population register data from Norway (n = 209,532) and Sweden (n = 592,491), this study addressed the relationship between partner choice and the timing of first marriage. We considered all migrant-background individuals born between 1972 and 1989 who were either native-born or who immigrated prior to age 18, relative to 10% random samples of the majority populations. The results demonstrate that marital timing patterns of migrant background individuals who married exogamously (that is, with a majority-background spouse or across their global region of origin) were more similar to the majority populations than among those who married endogamously (that is, with another migrant-background individual originating in the same global region). However, among immigrant-background individuals who endogamously married, there was evidence of a shift toward the Scandinavian pattern of later marriage across generations. Taken together the results provide an important starting point for investigations into the family life-courses and social position of children of immigrants in Europe, an increasingly large population subgroup currently entering family formation ages. Keywords Assortative mating, children of immigrants, endogamy, exogamy, marriage timing, second generationacceptedVersio

TiF1-Gamma Plays an Essential Role in Murine Hematopoiesis and Regulates Transcriptional Elongation of Erythroid Genes

Transcriptional regulators play critical roles in the regulation of cell fate during hematopoiesis. Previous studies in zebrafish have identified an essential role for the transcriptional intermediary factor TIF1γ in erythropoiesis by regulating the transcription elongation of erythroid genes. To study if TIF1γ plays a similar role in murine erythropoiesis and to assess its function in other blood lineages, we generated mouse models with hematopoietic deletion of TIF1γ. Our results showed a block in erythroid maturation in the bone marrow following tif1γ deletion that was compensated with enhanced spleen erythropoiesis. Further analyses revealed a defect in transcription elongation of erythroid genes in the bone marrow. In addition, loss of TIF1γ resulted in defects in other blood compartments, including a profound loss of B cells, a dramatic expansion of granulocytes and decreased HSC function. TIF1γ exerts its functions in a cell-autonomous manner as revealed by competitive transplantation experiments. Our study therefore demonstrates that TIF1γ plays essential roles in multiple murine blood lineages and that its function in transcription elongation is evolutionally conserved.Stem Cell and Regenerative Biolog

Satellite-derived increases in net primary productivity across North America, 1982-1998

We used a new 17‐year, high spatial resolution satellite record and a carbon cycle model to explore how changing net primary productivity (NPP) contributed to a proposed carbon (C) sink in North America. We found a small but significant increase in NPP, 0.03 Pg C yr^(−2) or 8% over 17 years, that could explain a substantial fraction of the C sink. The largest increases occurred in the central and southeastern United States, eastern Canada, and northwestern North America, and were consistent with NPP trends derived from forest inventories and crop yields. Interannual NPP variability was small, implying that the large interannual variability in the C sink found in previous studies were driven by changes in heterotrophic respiration

An arctic hydrologic system in transition: Feedbacks and impacts on terrestrial, marine, and human life

The pace of change in the arctic system during recent decades has captured the world\u27s attention. Observations and model simulations both indicate that the arctic experiences an amplified response to climate forcing relative to that at lower latitudes. At the core of these changes is the arctic hydrologic system, which includes ice, gaseous vapor in the atmosphere, liquid water in soils and fluvial networks on land, and the freshwater content of the ocean. The changes in stores and fluxes of freshwater have a direct impact on biological systems, not only of the arctic region itself, but also well beyond its bounds. In this investigation, we used a heuristic, graphical approach to distill the system into its fundamental parts, documented the key relationships between those parts as best we know them, and identified the feedback loops within the system. The analysis illustrates relationships that are well understood, but also reveals others that are either unfamiliar, uncertain, or unexplored. The graphical approach was used to provide a visual assessment of the arctic hydrologic system in one possible future state in which the Arctic Ocean is seasonally ice free

A phase II experience with neoadjuvant irinotecan (CPT-11), 5-fluorouracil (5-FU) and leucovorin (LV) for colorectal liver metastases

<p>Abstract</p> <p>Background</p> <p>Chemotherapy may improve survival in patients undergoing resection of colorectal liver metastases (CLM). Neoadjuvant chemotherapy may help identify patients with occult extrahepatic disease (averting unnecessary metastasectomy), and it provides <it>in vivo </it>chemosensitivity data.</p> <p>Methods</p> <p>A phase II trial was initiated in which patients with resectable CLM received CPT-11, 5-FU and LV for 12 weeks. Metastasectomy was performed unless extrahepatic disease appeared. Postoperatively, patients with stable or responsive disease received the same regimen for 12 weeks. Patients with progressive disease received either second-line chemotherapy or best supportive care. The primary endpoint was disease-free survival (DFS); secondary endpoints included overall survival (OS) and safety.</p> <p>Results</p> <p>35 patients were accrued. During preoperative chemotherapy, 16 patients (46%) had grade 3/4 toxicities. Resection was not possible in 5 patients. One patient died of arrhythmia following surgery, and 1 patient had transient liver failure. During the postoperative treatment phase, 12 patients (55%) had grade 3/4 toxicities. Deep venous thrombosis (DVT) occurred in 11 patients (34%) at various times during treatment. Of those who underwent resection, median DFS was 23.0 mo. and median OS has not been reached. The overall survival from time of diagnosis of liver metastases was 51.6 mo for the entire cohort.</p> <p>Conclusion</p> <p>A short course of chemotherapy prior to hepatic metastasectomy may serve to select candidates best suited for resection and it may also direct postoperative systemic treatment. Given the significant incidence of DVT, alternative systemic neoadjuvant regimens should be investigated, particularly those that avoid the use of a central venous line.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov NCT00168155.</p

Arctic system on trajectory to new state

The Arctic system is moving toward a new state that falls outside the envelope of glacial-interglacial fluctuations that prevailed during recent Earth history. This future Arctic is likely to have dramatically less permanent ice than exists at present. At the present rate of change, a summer ice-free Arctic Ocean within a century is a real possibility, a state not witnessed for at least a million years. The change appears to be driven largely by feedback-enhanced global climate warming, and there seem to be few, if any processes or feedbacks within the Arctic system that are capable of altering the trajectory toward this “super interglacial” state

Optimal search strategies for identifying sound clinical prediction studies in EMBASE

BACKGROUND: Clinical prediction guides assist clinicians by pointing to specific elements of the patient's clinical presentation that should be considered when forming a diagnosis, prognosis or judgment regarding treatment outcome. The numbers of validated clinical prediction guides are growing in the medical literature, but their retrieval from large biomedical databases remains problematic and this presents a barrier to their uptake in medical practice. We undertook the systematic development of search strategies ("hedges") for retrieval of empirically tested clinical prediction guides from EMBASE. METHODS: An analytic survey was conducted, testing the retrieval performance of search strategies run in EMBASE against the gold standard of hand searching, using a sample of all 27,769 articles identified in 55 journals for the 2000 publishing year. All articles were categorized as original studies, review articles, general papers, or case reports. The original and review articles were then tagged as 'pass' or 'fail' for methodologic rigor in the areas of clinical prediction guides and other clinical topics. Search terms that depicted clinical prediction guides were selected from a pool of index terms and text words gathered in house and through request to clinicians, librarians and professional searchers. A total of 36,232 search strategies composed of single and multiple term phrases were trialed for retrieval of clinical prediction studies. The sensitivity, specificity, precision, and accuracy of search strategies were calculated to identify which were the best. RESULTS: 163 clinical prediction studies were identified, of which 69 (42.3%) passed criteria for scientific merit. A 3-term strategy optimized sensitivity at 91.3% and specificity at 90.2%. Higher sensitivity (97.1%) was reached with a different 3-term strategy, but with a 16% drop in specificity. The best measure of specificity (98.8%) was found in a 2-term strategy, but with a considerable fall in sensitivity to 60.9%. All single term strategies performed less well than 2- and 3-term strategies. CONCLUSION: The retrieval of sound clinical prediction studies from EMBASE is supported by several search strategies