933 research outputs found
Counting defects with the two-point correlator
We study how topological defects manifest themselves in the equal-time
two-point field correlator. We consider a scalar field with Z_2 symmetry in 1,
2 and 3 spatial dimensions, allowing for kinks, domain lines and domain walls,
respectively. Using numerical lattice simulations, we find that in any number
of dimensions, the correlator in momentum space is to a very good approximation
the product of two factors, one describing the spatial distribution of the
defects and the other describing the defect shape. When the defects are
produced by the Kibble mechanism, the former has a universal form as a function
of k/n, which we determine numerically. This signature makes it possible to
determine the kink density from the field correlator without having to resort
to the Gaussian approximation. This is essential when studying field dynamics
with methods relying only on correlators (Schwinger-Dyson, 2PI).Comment: 11 pages, 7 figures
Use of construction and demolition recycled materials (C&Drm) in road pavements validated on experimental test sections
The construction activity usually generates large amounts of waste from different sources and processes. Due to the increasing shortage of space for landfill implementation and the costs associated with waste control regulations, derived from its ever increasing environmental protection requirements, the most desirable alternative is the reduction of construction and demolition waste volumes by means of their reuse and recycling. A research project, SUPREMA - Sustainable Application of Construction and Demolition Recycled Materials (C&DRM) in Road Infrastructures, is being developed by the National Laboratory for Civil Engineering (LNEC), and by the University of Lisbon (IST). This project seeks to contribute to the sustainable implementation of C&DRM in road pavements by improving the knowledge of the physical, mechanical and environmental behaviour of these materials when placed as aggregates in unbound pavement layers. Besides a general presentation of the research project and the construction procedures of a test pit structure where four different materials were applied, this paper presents some results related to the characteristics of the studied materials, supported by laboratory and by in situ tests performed with the FWD in the test pit structure. It was concluded that all materials demonstrate an acceptable structural performance
Translation, validity, and reliability of the European Portuguese version of the Touch Experiences and Attitudes Questionnaire
Background. Positive touch experiences have proved to be extremely important throughout our lifespan, with cascading effects on our social life. However, few questionnaires are available to measure attitudes and experiences of touch in the Portuguese population. This study aimed to translate and validate the European Portuguese version of the Touch Experiences and Attitudes Questionnaire (TEAQ), as a reliable and valid instrument to measure different aspects of affective touch experiences and attitudes. Methods. Therefore, an online sample of 384 (299 females and 85 males) participants, aged between 18 and 75 years (M = 24.59; SD = 9.56) was collected. Multidimensional Rasch model and confirmatory factor analysis were carried out, and also reliability and convergent and discriminant validity were determined. In addition, we examined sex differences in attitudes and experiences of touch. Results. Results showed good fit indexes for the 52-item six-factor model structure (friends and family touch, current intimate touch, childhood touch, attitudes to self-care, attitudes to intimate touch, and attitudes to unfamiliar touch). This instrument also showed good reliability and acceptable convergent and discriminant validity. Significant sex differences were found, with female participants reporting more positive touch experiences (including childhood touch, friends and family touch, and current intimate touch) and a more favourable attitude to self-care, with males showing a more positive attitude towards unfamiliar touch. Regarding attitudes towards the intimate touch, scores for both groups were comparable. Conclusion. Overall, the European Portuguese version of the TEAQ presented good psychometric properties and appears to be a reliable and valid self-report measure, being a useful and beneficial instrument in research and clinical settings
Metabonomics and Intensive Care
This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency medicine 2016. Other selected articles can be found online at http://www.biomedcentral.com/collections/annualupdate2016. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901
Contextual and individual assessment of dental pain period prevalence in adolescents: a multilevel approach
<p>Abstract</p> <p>Background</p> <p>Despite evidence that health and disease occur in social contexts, the vast majority of studies addressing dental pain exclusively assessed information gathered at individual level.</p> <p>Objectives</p> <p>To assess the association between dental pain and contextual and individual characteristics in Brazilian adolescents. In addition, we aimed to test whether contextual Human Development Index is independently associated with dental pain after adjusting for individual level variables of socio-demographics and dental characteristics.</p> <p>Methods</p> <p>The study used data from an oral health survey carried out in São Paulo, Brazil, which included dental pain, dental exams, individual socioeconomic and demographic conditions, and Human Development Index at area level of 4,249 12-year-old and 1,566 15-year-old schoolchildren. The Poisson multilevel analysis was performed.</p> <p>Results</p> <p>Dental pain was found among 25.6% (95%CI = 24.5-26.7) of the adolescents and was 33% less prevalent among those living in more developed areas of the city than among those living in less developed areas. Girls, blacks, those whose parents earn low income and have low schooling, those studying at public schools, and those with dental treatment needs presented higher dental-pain prevalence than their counterparts. Area HDI remained associated with dental pain after adjusting for individual level variables of socio demographic and dental characteristics.</p> <p>Conclusions</p> <p>Girls, students whose parents have low schooling, those with low <it>per capita </it>income, those classified as having black skin color and those with dental treatment needs had higher dental pain prevalence than their counterparts. Students from areas with low Human Development Index had higher prevalence of dental pain than those from the more developed areas regardless of individual characteristics.</p
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Bioavailability in soils
The consumption of locally-produced vegetables by humans may be an important exposure pathway for soil contaminants in many urban settings and for agricultural land use. Hence, prediction of metal and metalloid uptake by vegetables from contaminated soils is an important part of the Human Health Risk Assessment procedure. The behaviour of metals (cadmium, chromium, cobalt, copper, mercury, molybdenum, nickel, lead and zinc) and metalloids (arsenic, boron and selenium) in contaminated soils depends to a large extent on the intrinsic charge, valence and speciation of the contaminant ion, and soil properties such as pH, redox status and contents of clay and/or organic matter. However, chemistry and behaviour of the contaminant in soil alone cannot predict soil-to-plant transfer. Root uptake, root selectivity, ion interactions, rhizosphere processes, leaf uptake from the atmosphere, and plant partitioning are important processes that ultimately govern the accumulation ofmetals and metalloids in edible vegetable tissues. Mechanistic models to accurately describe all these processes have not yet been developed, let alone validated under field conditions. Hence, to estimate risks by vegetable consumption, empirical models have been used to correlate concentrations of metals and metalloids in contaminated soils, soil physico-chemical characteristics, and concentrations of elements in vegetable tissues. These models should only be used within the bounds of their calibration, and often need to be re-calibrated or validated using local soil and environmental conditions on a regional or site-specific basis.Mike J. McLaughlin, Erik Smolders, Fien Degryse, and Rene Rietr
Poverty, social exclusion and dental caries of 12-year-old children: a cross-sectional study in Lima, Peru
Background:
Socioeconomic differences in oral health have been reported in many countries. Poverty and social exclusion are two commonly used indicators of socioeconomic position in Latin America. The aim of this study was to explore the associations of poverty and social exclusion with dental caries experience in 12-year-old children.
Methods:
Ninety families, with a child aged 12 years, were selected from 11 underserved communities in Lima (Peru), using a two-stage cluster sampling. Head of households were interviewed with regard to indicators of poverty and social exclusion and their children were clinically examined for dental caries. The associations of poverty and social exclusion with dental caries prevalence were tested in binary logistic regression models.
Results:
Among children in the sample, 84.5% lived in poor households and 30.0% in socially excluded families. Out of all the children, 83.3% had dental caries. Poverty and social exclusion were significantly associated with dental caries in the unadjusted models (p = 0.013 and 0.047 respectively). In the adjusted model, poverty remained significantly related to dental caries (p = 0.008), but the association between social exclusion and dental caries was no longer significant (p = 0.077). Children living in poor households were 2.25 times more likely to have dental caries (95% confidence interval: 1.24; 4.09), compared to those living in non-poor households.
Conclusion:
There was support for an association between poverty and dental caries, but not for an association between social exclusion and dental caries in these children. Some potential explanations for these findings are discussed
Comprehensive analysis of Long non-coding RNA expression in dorsal root ganglion reveals cell type specificity and dysregulation following nerve injury
Dorsal root ganglion (DRG) neurons provide connectivity between peripheral tissues and spinal cord. Transcriptional plasticity within DRG sensory neurons after peripheral nerve injury contributes to nerve repair but also leads to maladaptive plasticity, including the development of neuropathic pain. This study presents tissue and neuron specific expression profiling of both known and novel Long Non-Coding RNAs (LncRNAs) in rodent DRG following nerve injury. We have identified a large number of novel LncRNAs expressed within rodent DRG, a minority of which were syntenically conserved between mouse, rat and human and which including both- intergenic and antisense LncRNAs. We have also identified neuron type-specific LncRNAs in mouse DRG, and LncRNAs that are expressed in human IPS cell-derived sensory neurons. We show significant plasticity in LncRNA expression following nerve injury, which in mouse is strain and gender dependant. This resource is publicly available and will aid future studies of DRG neuron identity and the transcriptional landscape in both naïve and injured DRG. We present our work regarding novel antisense and intergenic LncRNAs as an online searchable database, accessible from PainNetworks (http://www.painnetworks.org/). We have also integrated all annotated gene expression data in PainNetworks so they can be examined in the context of their protein interactions
X-Ray Spectroscopy of Stars
(abridged) Non-degenerate stars of essentially all spectral classes are soft
X-ray sources. Low-mass stars on the cooler part of the main sequence and their
pre-main sequence predecessors define the dominant stellar population in the
galaxy by number. Their X-ray spectra are reminiscent, in the broadest sense,
of X-ray spectra from the solar corona. X-ray emission from cool stars is
indeed ascribed to magnetically trapped hot gas analogous to the solar coronal
plasma. Coronal structure, its thermal stratification and geometric extent can
be interpreted based on various spectral diagnostics. New features have been
identified in pre-main sequence stars; some of these may be related to
accretion shocks on the stellar surface, fluorescence on circumstellar disks
due to X-ray irradiation, or shock heating in stellar outflows. Massive, hot
stars clearly dominate the interaction with the galactic interstellar medium:
they are the main sources of ionizing radiation, mechanical energy and chemical
enrichment in galaxies. High-energy emission permits to probe some of the most
important processes at work in these stars, and put constraints on their most
peculiar feature: the stellar wind. Here, we review recent advances in our
understanding of cool and hot stars through the study of X-ray spectra, in
particular high-resolution spectra now available from XMM-Newton and Chandra.
We address issues related to coronal structure, flares, the composition of
coronal plasma, X-ray production in accretion streams and outflows, X-rays from
single OB-type stars, massive binaries, magnetic hot objects and evolved WR
stars.Comment: accepted for Astron. Astrophys. Rev., 98 journal pages, 30 figures
(partly multiple); some corrections made after proof stag
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