349 research outputs found
A low-frequency study of recently identified double-double radio galaxies
In order to understand the possible mechanisms of recurrent jet activity in
radio galaxies and quasars, which are still unclear, we have identified such
sources with a large range of linear sizes (220 917 kpc), and hence time
scales of episodic activity. Here we present high-sensitivity 607-MHz Giant
Metrewave Radio Telescope (GMRT) images of 21 possible double-double radio
galaxies (DDRGs) identified from the FIRST survey to confirm their episodic
nature. These GMRT observations show that none of the inner compact components
suspected to be hot-spots of the inner doubles are cores having a flat radio
spectrum, confirming the episodic nature of these radio sources. We have
indentified a new DDRG with a candidate quasar, and have estimated the upper
spectral age limits for eight sources which showed marginal evidence of
steepening at higher frequencies. The estimated age limits (11 52 Myr) are
smaller than those of the large-sized ( 1 Mpc) DDRGs.Comment: Accepted for publication in MNRAS. 14 pages, 7 figure
Frailty among older adults and its distribution in England
Background: Information on the spatial distribution of the frail population is crucial to inform service planning in health and social care. Objectives: To estimate small-area frailty prevalence among older adults using survey data. To assess whether prevalence differs between urban, rural, coastal and inland areas of England. Design: Using data from the English Longitudinal Study of Ageing (ELSA), ordinal logistic regression was used to predict the probability of frailty, according to age, sex and area deprivation. Probabilities were applied to demographic and economic information in 2020 population projections to estimate the district-level prevalence of frailty. Results: The prevalence of frailty in adults aged 50+ (2020) in England was estimated to be 8.1 [95% CI 7.3–8.8]%. We found substantial geographic variation, with the prevalence of frailty varying by a factor of 4.0 [3.5–4.4] between the most and least frail areas. A higher prevalence of frailty was found for urban than rural areas, and coastal than inland areas. There are widespread geographic inequalities in healthy ageing in England, with older people in urban and coastal areas disproportionately frail relative to those in rural and inland areas. Conclusions: Interventions aimed at reducing inequalities in healthy ageing should be targeted at urban and coastal areas, where the greatest benefit may be achieved
Viewing Nature Scenes Positively Affects Recovery of Autonomic Function Following Acute-Mental Stress
A randomized crossover study explored whether viewing different scenes prior to a stressor altered autonomic function during the recovery from the stressor. The two scenes were (a) nature (composed of trees, grass, fields) or (b) built (composed of man-made, urban scenes lacking natural characteristics) environments. Autonomic function was assessed using noninvasive techniques of heart rate variability; in particular, time domain analyses evaluated parasympathetic activity, using root-mean-square of successive differences (RMSSD). During stress, secondary cardiovascular markers (heart rate, systolic and diastolic blood pressure) showed significant increases from baseline which did not differ between the two viewing conditions. Parasympathetic activity, however, was significantly higher in recovery following the stressor in the viewing scenes of nature condition compared to viewing scenes depicting built environments (RMSSD; 50.0 ± 31.3 vs 34.8 ± 14.8 ms). Thus, viewing nature scenes prior to a stressor alters autonomic activity in the recovery period. The secondary aim was to examine autonomic function during viewing of the two scenes. Standard deviation of R-R intervals (SDRR), as change from baseline, during the first 5 min of viewing nature scenes was greater than during built scenes. Overall, this suggests that nature can elicit improvements in the recovery process following a stressor. © 2013 American Chemical Society
MetaBags: Bagged Meta-Decision Trees for Regression
Ensembles are popular methods for solving practical supervised learning
problems. They reduce the risk of having underperforming models in
production-grade software. Although critical, methods for learning
heterogeneous regression ensembles have not been proposed at large scale,
whereas in classical ML literature, stacking, cascading and voting are mostly
restricted to classification problems. Regression poses distinct learning
challenges that may result in poor performance, even when using well
established homogeneous ensemble schemas such as bagging or boosting.
In this paper, we introduce MetaBags, a novel, practically useful stacking
framework for regression. MetaBags is a meta-learning algorithm that learns a
set of meta-decision trees designed to select one base model (i.e. expert) for
each query, and focuses on inductive bias reduction. A set of meta-decision
trees are learned using different types of meta-features, specially created for
this purpose - to then be bagged at meta-level. This procedure is designed to
learn a model with a fair bias-variance trade-off, and its improvement over
base model performance is correlated with the prediction diversity of different
experts on specific input space subregions. The proposed method and
meta-features are designed in such a way that they enable good predictive
performance even in subregions of space which are not adequately represented in
the available training data.
An exhaustive empirical testing of the method was performed, evaluating both
generalization error and scalability of the approach on synthetic, open and
real-world application datasets. The obtained results show that our method
significantly outperforms existing state-of-the-art approaches
Deteriorating health satisfaction among immigrants from Eastern Europe to Germany
BACKGROUND: Migrants from Eastern Europe constitute more than 5% of Germany's population. Since population health in their countries of origin is poor their health status upon arrival may be worse than that of the native-born German population (hypothesis H1). As a minority, they may be socio-economically disadvantaged (H2), and their health status may deteriorate quickly (H3). METHODS: We compared data from 1995 and 2000 for immigrants from Eastern Europe (n = 353) and a random sample of age-matched Germans (n = 2, 824) from the German Socioeconomic Panel. We tested H1-3 using health satisfaction, as a proxy for health status, and socioeconomic indicators. We compared changes over time within groups, and between immigrants and Germans. We assessed effects of socio-economic status and being a migrant on declining health satisfaction in a regression model. RESULTS: In 1995, immigrants under 55 years had a significantly higher health satisfaction than Germans. Above age 54, health satisfaction did not differ. By 2000, immigrants' health satisfaction had declined to German levels. Whereas in 1995 immigrants had a significantly lower SES, differences five years later had declined. In the regression model, immigrant status was much stronger associated with declining health satisfaction than low SES. CONCLUSION: In contrast to H1, younger immigrants had an initial health advantage. Immigrants were initially socio-economically disadvantaged (H2), but their SES improved over time. The decrease in health satisfaction was much steeper in immigrants and this was not associated with differences in SES (H3). Immigrants from Eastern Europe have a high risk of deteriorating health, in spite of socio-economic improvements
Deteriorating health satisfaction among immigrants from Eastern Europe to Germany
BACKGROUND: Migrants from Eastern Europe constitute more than 5% of Germany's population. Since population health in their countries of origin is poor their health status upon arrival may be worse than that of the native-born German population (hypothesis H1). As a minority, they may be socio-economically disadvantaged (H2), and their health status may deteriorate quickly (H3). METHODS: We compared data from 1995 and 2000 for immigrants from Eastern Europe (n = 353) and a random sample of age-matched Germans (n = 2, 824) from the German Socioeconomic Panel. We tested H1-3 using health satisfaction, as a proxy for health status, and socioeconomic indicators. We compared changes over time within groups, and between immigrants and Germans. We assessed effects of socio-economic status and being a migrant on declining health satisfaction in a regression model. RESULTS: In 1995, immigrants under 55 years had a significantly higher health satisfaction than Germans. Above age 54, health satisfaction did not differ. By 2000, immigrants' health satisfaction had declined to German levels. Whereas in 1995 immigrants had a significantly lower SES, differences five years later had declined. In the regression model, immigrant status was much stronger associated with declining health satisfaction than low SES. CONCLUSION: In contrast to H1, younger immigrants had an initial health advantage. Immigrants were initially socio-economically disadvantaged (H2), but their SES improved over time. The decrease in health satisfaction was much steeper in immigrants and this was not associated with differences in SES (H3). Immigrants from Eastern Europe have a high risk of deteriorating health, in spite of socio-economic improvements
Relative Health Effects of Education, Socioeconomic Status and Domestic Gender Inequity in Sweden: A Cohort Study
Introduction: Limited existing research on gender inequities suggests that for men workplace atmosphere shapes wellbeing while women are less susceptible to socioeconomic or work status but vulnerable to home inequities. Methods: Using the 2007 Northern Swedish Cohort (n = 773) we identified relative contributions of perceived gender inequities in relationships, financial strain, and education to self-reported health to determine whether controlling for sex, examining interactions between sex and other social variables, or sex-disaggregating data yielded most information about sex differences. Results and Discussion: Men had lower education but also less financial strain, and experienced less gender inequity. Overall, low education and financial strain detracted from health. However, sex-disaggregated data showed this to be true for women, whereas for men only gender inequity at home affected health. In the relatively egalitarian Swedish environment where women more readily enter all work arenas and men often provide parenting, traditional primacy of the home environment (for women) and the work environment (for men) in shaping health is reversing such that perceived domestic gender inequity has a significant health impact on men, while for women only education and financial strain are contributory. These outcomes were identified only when data were sex-disaggregated
Work-time underemployment and financial hardship: class inequalities and recession in the UK
The economic crisis that led to recession in the UK in 2008–9 impacted in multiple ways on work and economic life. This article examines changes to the work-time of employees. The UK stood out for its recessionary expansion of work-time underemployment. Working in a job that provides ‘too few’ hours can have serious ramifications for the economic livelihood of workers. Working-class workers are central here. Drawing on analysis of large-scale survey data, the article identifies that workers in lower level occupations experienced the most substantial post-recessionary growth in the proportions working ‘too few’ hours. Did these work-time changes narrow or widen class inequalities in feelings of financial hardship? The article concludes that although middle-class workers also saw their financial positions damaged, this so-called ‘first middle-class recession’ did not erode class inequalities in financial hardship among UK workers
Variations in surface ozone and carbon monoxide in the Kathmandu Valley and surrounding broader regions during SusKat-ABC field campaign: role of local and regional sources
Air pollution resulting from rapid urbanization and associated human
activities in the Kathmandu Valley of Nepal has been leading to serious
public health concerns over the past 2 decades. These concerns led to a
multinational field campaign SusKat-ABC (Sustainable atmosphere for the
Kathmandu Valley – Atmospheric Brown Clouds) that measured different trace
gases, aerosols and meteorological parameters in the Kathmandu Valley and
surrounding regions during December 2012 to June 2013 to understand local- to
regional-scale processes influencing air quality of the Kathmandu Valley.
This study provides information about the regional distribution of ozone and
some precursor gases using simultaneous in situ measurements from a
SusKat-ABC supersite at Bode, Nepal, and two Indian sites: a high-altitude
site, Nainital, located in the central Himalayan region and a low-altitude
site,
Pantnagar, located in the Indo-Gangetic Plain (IGP). The diurnal variations at
Bode showed a daytime buildup in O3 while CO shows morning and
evening peaks. Similar variations (with lower levels) were also observed at
Pantnagar but not at Nainital. Several events of hourly ozone levels
exceeding 80 ppbv were also observed at Bode. The CO levels showed a
decrease from their peak level of about 2000 ppbv in January to about
680 ppbv in June at Bode. The hourly mean ozone and CO levels showed a
strong negative correlation during winter (r2 = 0.82 in January and
r2 = 0.71 in February), but this negative correlation gradually becomes
weaker, with the lowest value in May (r2 = 0.12). The background
O3 and CO mixing ratios at Bode were estimated to be about 14 and
325 ppbv, respectively. The rate of change of ozone at Bode showed a more
rapid increase ( ∼ 17 ppbv h−1) during
morning than the decrease in the evening (5–6 ppbv h−1), suggesting
the
prevalence of a semi-urban environ. The lower CO levels
during spring suggest that regional transport also contributes appreciably
to springtime ozone enhancement in the Kathmandu Valley on top of the local
in situ ozone production. We show that regional pollution resulting from
agricultural crop residue burning in northwestern IGP led to simultaneous
increases in O3 and CO levels at Bode and Nainital during the first week
of May 2013. A biomass-burning-induced increase in ozone and related gases was
also confirmed by a global model and balloon-borne observations over
Nainital. A comparison of surface ozone variations and composition of light
non-methane hydrocarbons among different sites indicated the differences in
emission sources of the Kathmandu Valley and the IGP. These results highlight
that it is important to consider regional sources in air quality management
of the Kathmandu Valley.</p
Security of data science and data science for security
In this chapter, we present a brief overview of important topics regarding the connection of data science and security. In the first part, we focus on the security of data science and discuss a selection of security aspects that data scientists should consider to make their services and products more secure. In the second part about security for data science, we switch sides and present some applications where data science plays a critical role in pushing the state-of-the-art in securing information systems. This includes a detailed look at the potential and challenges of applying machine learning to the problem of detecting obfuscated JavaScripts
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