1,305 research outputs found
Models of OH Maser Variations in U Her
Arecibo spectra of the mainline OH maser emission from U Her over more than a
decade show variations of the OH emission over these time scales. These
observations are combined with high spatial resolution VLBA maps to investigate
the causes of the variations in the velocities of the maser components. Global
properties of the dust shell, such as accelerations, variations in the pump and
shell-wide magnetic field changes are examined as possibilities, and
eliminated. A possible solution to the problem involving plasma turbulence and
the local magnetic field is introduced, and the relevant time scales of the
turbulence are calculated. The turbulent velocity field yields time scales of
the turbulence are calculated. The turbulent velocity field yields time scales
that are too long (of order centuries), while the turbulent magnetic field
produces variations on appropriate time scales of a few years. A line-of-sight
model of the turbulence is developed and investigated. The complete exploration
of this solution requires extensive theoretical and observational work.
Possible avenues of investigation of the plasma turbulence model are presented.Comment: 23 pages, 17 figures, ApJ: accepted Sept, 199
Tunable dipolar magnetism in high-spin molecular clusters
We report on the Fe17 high-spin molecular cluster and show that this system
is an exemplification of nanostructured dipolar magnetism. Each Fe17 molecule,
with spin S=35/2 and axial anisotropy as small as D=-0.02K, is the magnetic
unit that can be chemically arranged in different packing crystals whilst
preserving both spin ground-state and anisotropy. For every configuration,
molecular spins are correlated only by dipolar interactions. The ensuing
interplay between dipolar energy and anisotropy gives rise to macroscopic
behaviors ranging from superparamagnetism to long-range magnetic order at
temperatures below 1K.Comment: Replaced with version accepted for publication in Physical Review
Letter
Evaluating the Pennebaker Paradigm with Bereaved Emerging Adults: Applications of Text Analysis
Bereavement is an important research area as it can result in grief reactions that lead to serious psychological and health consequences, particularly for the at-risk group of emerging adults (Arnett, 2000; Balk, Walker, & Baker, 2010; Fisher, Murray, & Frazer, 1985; Stroebe, Schut, & Stroebe, 2007). Expressive writing is a well-researched intervention for trauma and adjustment, yet research repeatedly has revealed null results with the classic Pennebaker paradigm as a bereavement intervention (Stroebe et al., 2002; Stroebe, Schut, & Stroebe, 2006). It may be premature, however, to conclude expressive writing is ineffective for the bereaved due to limitations in extant research. For example, Pennebakerâs paradigm is based on the premise that participants freely choose the stressful topic to write about, whereas expressive writing bereavement studies have required participants to write about their loss (Collison & Gramling, manuscript in preparation).
The present study reports on data from a larger study (Konig, Eonta, Dyal, & Vrana, 2014; N=246) that assessed psychological and physiological outcomes in college students who wrote about a traumatic stressor using Pennebakerâs paradigm. This provided the opportunity to rigorously test it with bereavement and compare death loss to other forms of trauma. Analyses examined the impact of expressive writing with the bereaved who freely identified death loss as the traumatic stressor (n=69) and were randomly assigned to either emotional disclosure or control writing on outcome measures of physical symptoms (PILL), event-related distress (DTS), and depression (CES-D). Linguistic Inquiry and Word Count (LIWC; Pennebaker, Mayne, & Francis, 1997) and Latent Semantic Analysis (LSA; Campbell & Pennebaker, 2003) results were also used to compare these groups. Exploratory analyses investigated potential differences between the bereaved and those who endorsed a non-bereavement trauma (âother traumaâ; n=71) using outcome measures and text analytic techniques (i.e., PILL, DTS, CES-D; LIWC, LSA). Results were consistent with findings from previous expressive writing studies with the bereaved, in that the intervention resulted in no detectable benefits when compared with control writing. No remarkable differences between the bereaved and âother traumaâ participants emerged. Researchersâ time may be better spent examining more clinically relevant writing exercises for bereavement interventions
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How should we turn data into decisions in AgriFood?
The AgriFood supply chain is under significant pressures related to food security, climate change, and consumer demands for affordable and higher quality food. Various technologies are already deployed producing a large amount of data, which can be utilised to guide decision-making to improve productivity, reduce wastage, and increase traceability across the AgriFood supply chain. Several examples of the use of data are given, including improving efficiency in livestock production, supporting automation and use of robotics in crop production, increasing food safety and evidencing its provenance. The opportunities and ways forward were discussed at a workshop in November 2017, run by the Society of Chemical Industry and the Knowledge Transfer Network in the UK. This paper presents a summary of the key messages from the presentations and focus-group discussions during this event, as interpreted by the authors. A number of challenges in digitalisation of the AgriFood supply chain are discussed, such as low inter-operability of different data sets, silo mentality, low willingness to share data and a significant skills gap. Various approaches are presented that could help to unlock the benefits of using data, from practical support to producers and addressing skills gaps, to industrial leadership and the role of government departments and regulatory bodies in leading by example. Looking forward, data are already revolutionising the AgriFood supply chain, however, the benefits will remain piecemeal until the leaders of today are able to bring together the disparate groups into a cohesive whole
Legal determinants of external finance revisited : the inverse relationship between investor protection and societal well-being
This paper investigates relationships between corporate governance traditions and quality of life as measured by a number of widely reported indicators. It provides an empirical analysis of indicators of societal health in developed economies using a classification based on legal traditions. Arguably the most widely cited work in the corporate governance literature has been the collection of papers by La Porta et al. which has shown, inter alia, statistically significant relationships between legal traditions and various proxies for investor protection. We show statistically significant relationships between legal traditions and various proxies for societal health. Our comparative evidence suggests that the interests of investors may not be congruent with the interests of wider society, and that the criteria for judging the effectiveness of approaches to corporate governance should not be restricted to financial metrics
Association of BMI category with change in childrenâs physical activity between ages 6 and 11 years:a longitudinal study
Association of BMI category with change in childrenâs physical activity between ages 6 and 11 years:a longitudinal study
Associations of body mass index, physical activity and sedentary time with blood pressure in primary school children from south-west England: a prospective study
Elevated blood pressure in children is a significant risk factor for the development of cardiovascular disease in adulthood. We examined how children's body mass index (BMI), physical activity and sedentary time at ages 9 and 11 are associated with blood pressure at age 11. Data were from 1283 children from Bristol, UK, who participated in the study aged 11 years, 797 of whom also participated in the study aged 9 years. Child height, weight and blood pressure were measured, and children wore accelerometers for five days, from which moderate-to-vigorous-intensity physical activity and sedentary minutes per day were derived. Multiple imputation of missing data and adjusted linear and logistic regression models were used to examine associations. Child BMI at 11 years was cross-sectionally associated with higher systolic and diastolic blood pressure (mean difference [95% confidence interval]: 0.91 [0.32 to 1.50] mm Hg and 1.08 [0.54 to 1.62] mm Hg, respectively, per standard deviation (SD) of BMI). BMI at age 9 was also positively associated with diastolic blood pressure at age 11 (1.16 mmHg per two years [0.49 to 1.84], per SD of BMI). For girls, sedentary time at age 9 years was associated with increased odds of having high systolic blood pressure at age 11 (odds ratio: 1.08 [1.01 to 1.16], per 10 minutes per day). There was no evidence of associations between sedentary time and blood pressure among boys. Similarly, there was little evidence that physical activity was associated with blood pressure in either cross-sectional or prospective analyses. Effective strategies are needed to prevent excess bodyweight among children in order to reduce cardiovascular disease risk
Modelling Conformational Flexibility in a Spectrally Addressable Molecular Multi-Qubit Model System
Dipolar coupled multi-spin systems have the potential to be used as molecular qubits. Herein we report the synthesis of a molecular multi-qubit model system with three individually addressable, weakly interacting, spin (Formula presented.) centres of differing g-values. We use pulsed Electron Paramagnetic Resonance (EPR) techniques to characterise and separately address the individual electron spin qubits; CuII, Cr7Ni ring and a nitroxide, to determine the strength of the inter-qubit dipolar interaction. Orientation selective Relaxation-Induced Dipolar Modulation Enhancement (os-RIDME) detecting across the CuII spectrum revealed a strongly correlated CuII-Cr7Ni ring relationship; detecting on the nitroxide resonance measured both the nitroxide and CuII or nitroxide and Cr7Ni ring correlations, with switchability of the interaction based on differing relaxation dynamics, indicating a handle for implementing EPR-based quantum information processing (QIP) algorithms
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