555 research outputs found
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A Multivariate Analysis of United States and Global Real Estate Investment Trusts
Using daily data for the period February 2006 to July 2013 we examine the return and volatility linkages between the two main United States REIT sub-sectors and global linkages between the Americas, Europe and the Asia Pacific regions using the BEKK-GARCH and the DCC-GARCH models. We find that there is no evidence of any volatility spillovers between the US sub-sectors. By contrast, we find evidence of volatility spillovers between the Asia Pacific and the Americas, the Asia Pacific and Europe but no spillovers between the United States and Europe. Our results suggest that the REIT market is becoming increasingly globalized and that investors need to consider time varying volatility and correlations across different regions of the world when forming their optimal portfolio-allocations
Breakdown of the adiabatic limit in low dimensional gapless systems
It is generally believed that a generic system can be reversibly transformed
from one state into another by sufficiently slow change of parameters. A
standard argument favoring this assertion is based on a possibility to expand
the energy or the entropy of the system into the Taylor series in the ramp
speed. Here we show that this argumentation is only valid in high enough
dimensions and can break down in low-dimensional gapless systems. We identify
three generic regimes of a system response to a slow ramp: (A) mean-field, (B)
non-analytic, and (C) non-adiabatic. In the last regime the limits of the ramp
speed going to zero and the system size going to infinity do not commute and
the adiabatic process does not exist in the thermodynamic limit. We support our
results by numerical simulations. Our findings can be relevant to
condensed-matter, atomic physics, quantum computing, quantum optics, cosmology
and others.Comment: 11 pages, 5 figures, to appear in Nature Physics (originally
submitted version
School, peer and family relationships and adolescent substance use, subjective wellbeing and mental health symptoms in Wales: a cross sectional study
Positive relationships with family, friends and school staff are consistently linked with health and wellbeing during adolescence, though fewer studies explore how these micro-systems interact to influence adolescent health. This study tests the independent and interacting roles of family, peer and school relationships in predicting substance use, subjective wellbeing and mental health symptoms among 11–16 year olds in Wales. It presents cross-sectional analyses of the 2013 Health Behaviour in School-aged Children survey, completed by 9055 young people aged 11–16 years. Multilevel logistic regression analyses are used to test associations of family communication, family support, relationships with school staff, school peer connectedness, and support from friends, with tobacco use, cannabis use, alcohol use, subjective wellbeing and mental health symptoms. Positive relationships with family and school staff were consistently associated with better outcomes. Support from friends was associated with higher use of all substances, while higher school peer connectedness was associated with better subjective wellbeing and mental health. Better relationships with school staff were most strongly associated with positive subjective wellbeing, and fewer mental health symptoms where pupils reported less family support. Support from friends was associated with higher cannabis use and worse mental health among pupils with lower family support. Relationships with family and school staff may be important in protecting young people against substance use, and improving wellbeing and mental health. Interventions focused on student-staff relationships may be important for young people with less family support. Interventions based on peer support should be mindful of potential harmful effects for pupils with less support from family
Discharge–calcium concentration relationships in streams of the Amazon and Cerrado of Brazil : soil or land use controlled
Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of springer for personal use, not for redistribution. The definitive version was published in Biogeochemistry 105 (2011): 19-35, doi:10.1007/s10533-011-9574-2.Stream discharge-concentration relationships are indicators of terrestrial ecosystem function. Throughout the Amazon and Cerrado regions of Brazil rapid changes in land use and land cover may be altering these hydrochemical relationships. The current analysis focuses on factors controlling the discharge-calcium (Ca) concentration relationship since previous research in these regions has demonstrated both positive and negative slopes in linear log10discharge-log10Ca concentration regressions. The objective of the current study was to evaluate factors controlling stream discharge-Ca concentration relationships including year, season, stream order, vegetation cover, land use, and soil classification. It was hypothesized that land use and soil class are the most critical attributes controlling discharge-Ca concentration relationships. A multilevel, linear regression approach was utilized with data from 28 streams throughout Brazil. These streams come from three distinct regions and varied broadly in watershed size (106 ha) and discharge (10-5.7 to 103.2 m3 sec-1). Linear regressions of log10Ca versus log10discharge in 13 streams have a preponderance of negative slopes with only two streams having significant positive slopes. An ANOVA decomposition suggests the effect of discharge on Ca concentration is large but variable. Vegetation cover, which incorporates aspects of land use, explains the largest proportion of the variance in the effect of discharge on Ca followed by season and year. In contrast, stream order, land use, and soil class explain most of the variation in stream Ca concentration. In the current data set, soil class, which is related to lithology, has an important effect on Ca concentration but land use, likely through its effect on runoff concentration and hydrology, has a greater effect on discharge-concentration relationships.This research was supported by grant #’s NCC5-686 and NNG06GE88A of NASA’s Terrestrial Ecology Program as part of the Large-scale Biosphere-Atmosphere Experiment in Amazonia (LBA-ECO) project
Advanced adenoma diagnosis with FDG PET in a visibly normal mucosa: a case report
<p>Abstract</p> <p>Background</p> <p>An accurate, early diagnosis and treatment of adenomatous polyp can curtail progression to colorectal cancer. F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) reveals the biochemical changes associated with the development of many cancers which precede the appearance of gross anatomical changes that may be visualized during surgical resection or via imaging with MR or CT.</p> <p>Intervention</p> <p>We detail the history of a 64 year old female who had a whole-body FDG PET scan as a part of an employee wellness program. A dose of 12.2 mCi of F-18 labeled FDG was administered.</p> <p>Results</p> <p>A focal cecal uptake with a standardized uptake value (SUV) of 8.9 was found on the PET scan. Conversely, only normal mucosa was observed during a colonoscopy done 2 months after the PET scan. Motivated by the PET scan finding, the colonoscopist performed a biopsy which revealed a villous adenoma without high grade dysplasia. Pathology from tissue extracted during an exploratory laparatomy completed one month later found the lesion to be a villous adenoma with high grade dysplasia.</p> <p>Conclusion</p> <p>Whole-body FDG PET scan revealed the biochemical metabolic changes in malignancy that preceded the appearance of any gross anatomical abnormality. A positive FDG PET scan indicative of colorectal cancer should be followed up with a colonoscopy and biopsy even in a visibly normal mucosa.</p
School wellbeing among children in grades 1 - 10
<p>Abstract</p> <p>Background</p> <p>Determinants of children's school wellbeing have not been extensively studied. In this cross-sectional study of school children we assessed how factors assumed to promote wellbeing and factors assumed to adversely influence wellbeing were associated with self-reported wellbeing in school.</p> <p>Methods</p> <p>Children from five schools, 230 boys and 189 girls in grades 1-10, responded to the same set of questions. We used proportional odds logistic regression to assess the associations of promoting and restraining factors with school wellbeing.</p> <p>Results</p> <p>In a multivariable analysis, degree of school wellbeing in boys was strongly and positively related to enjoying school work (odds ratio, 3.84, 95% CI 2.38 to 6.22) and receiving necessary help (odds ratio, 3.55, 95% CI 2.17 to 5.80) from teachers. In girls, being bothered during lessons was strongly and negatively associated with school wellbeing (odds ratio, 0.43, 95% CI 0.22 to 0.85).</p> <p>Conclusions</p> <p>Different factors may determine school wellbeing in boys and girls, but for both genders, factors relevant for lessons may be more important than factors related to recess. Especially in boys, the student-teacher relationship may be of particular importance.</p
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Determinants of woody encroachment and cover in African savannas
Savanna ecosystems are an integral part of the African landscape and sustain the livelihoods of millions of people. Woody encroachment in savannas is a widespread phenomenon but its causes are widely debated. We review the extensive literature on woody encroachment to help improve understanding of the possible causes and to highlight where and how future scientific efforts to fully understand these causes should be focused. Rainfall is the most important determinant of maximum woody cover across Africa, but fire and herbivory interact to reduce woody cover below the maximum at many locations. We postulate that woody encroachment is most likely driven by CO2 enrichment and propose a two-system conceptual framework, whereby mechanisms of woody encroachment differ depending on whether the savanna is a wet or dry system. In dry savannas, the increased water-use efficiency in plants relaxes precipitation-driven constraints and increases woody growth. In wet savannas, the increase of carbon allocation to tree roots results in faster recovery rates after disturbance and a greater likelihood of reaching sexual maturity. Our proposed framework can be tested using a mixture of experimental and earth observational techniques. At a local level, changes in precipitation, burning regimes or herbivory could be driving woody encroachment, but are unlikely to be the explanation of this continent-wide phenomenon
Developing and testing a measure of consultation-based reassurance for people with low back pain in primary care:a cross-sectional study
BACKGROUND: Reassurance from physicians is commonly recommended in guidelines for the management of low back pain (LBP), but the process of reassurance and its impact on patients is poorly researched. We aimed to develop a valid and reliable measure of the process of reassurance during LBP consultations. METHODS: Items representing the data-gathering stage of the consultation and affective and cognitive reassurance were generated from literature on physician-patient communication and piloted with expert researchers and physicians, a Patient and Public Involvement group, and LBP patients to form a questionnaire. Patients presenting for LBP at 43 General Practice surgeries were sent the questionnaire. The questionnaire was analysed with Rasch modelling, using two samples from the same population of recent LBP consultations: the first (n = 157, follow-up n = 84) for exploratory analysis and the second (n = 162, follow-up n = 74) for confirmatory testing. Responses to the questionnaire were compared with responses to satisfaction and enablement scales to assess the external validity of the items, and participants completed the questionnaire again one-week later to assess test-retest reliability. RESULTS: The questionnaire was separated into four subscales: data-gathering, relationship-building, generic reassurance, and cognitive reassurance, each containing three items. All subscales showed good validity within the Rasch models, and good reliability based on person- and item-separations and test-retest reliability. All four subscales were significantly positively correlated with satisfaction and enablement for both samples. The final version of the questionnaire is presented here. CONCLUSIONS: Overall, the measure has demonstrated a good level of validity and generally acceptable reliability. This is the first measure to focus specifically on reassurance for LBP in primary care settings, and will enable researchers to further understanding of what is reassuring within the context of low back pain consultations, and how outcomes are affected by different types of reassurance. Additionally, the measure may provide a useful training and audit tool for physicians. The new measure requires testing in prospective cohorts, and would benefit from further validation against ethnographic observation of consultations in real time
Halal market emergence and export opportunity: the comparative advantage perspective
The comparative advantage theory of international trade states that countries should export commodities for which they have high comparative advantage and import commodities for which they have low comparative advantage. Analyzing the Halal trade flows for Malaysia’s 11 food/foodrelated commodities from 1991 to 2012, this study finds an interesting development of the standard view of comparative advantage in the emerging Halal export market. It finds that the greater the country’s current comparative advantage in an exported good, the higher the risk of export diversion (one- or two-way causality) between the Halal market and the conventional market with the country’s expansion of Halal exports; while the diversion risk disappears with lower current comparative advantage. Thus, the study suggests that if a country wants to take advantage of the fast-emerging market, it should aim to expand export of commodities with relatively low current comparative advantage but high demand in the emerging market
Measuring the Impacts of Community-based Grasslands Management in Mongolia's Gobi
We assessed a donor-funded grassland management project designed to create both conservation and livelihood benefits in the rangelands of Mongolia's Gobi desert. The project ran from 1995 to 2006, and we used remote sensing Normalized Differential Vegetation Index data from 1982 to 2009 to compare project grazing sites to matched control sites before and after the project's implementation. We found that the productivity of project grazing sites was on average within 1% of control sites for the 20 years before the project but generated 11% more biomass on average than the control areas from 2000 to 2009. To better understand the benefits of the improved grasslands to local people, we conducted 280 household interviews, 8 focus group discussions, and 31 key informant interviews across 6 districts. We found a 12% greater median annual income as well as a range of other socioeconomic benefits for project households compared to control households in the same areas. Overall, the project generated measurable benefits to both nature and people. The key factors underlying project achievements that may be replicable by other conservation projects include the community-driven approach of the project, knowledge exchanges within and between communities inside and outside the country, a project-supported local community organizer in each district, and strong community leadership
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