434 research outputs found
Equation of state for the two component Van der Waals gas with relativistic excluded volumes
A canonical partition function for the two-component excluded volume model is derived, leading to two di erent van der Waals approximations. The one is known as the Lorentz-Berthelot mixture and the other has been proposed recently. Both models are analysed in the canonical and grand canonical ensemble. In comparison with the one-component van der Waals excluded volume model the suppression of particle densities is reduced in these two-component formulations, but in two essentially di erent ways. Presently used multi-component models have no such reduction. They are shown to be not correct when used for components with di erent hard-core radii. For high temperatures the excluded volume interaction is refined by accounting for the Lorentz contraction of the spherical excluded volumes, which leads to a distinct enhancement of lighter particles. The resulting e ects on pion yield ratios are studied for AGS and SPS data
Overweight and obesity at school entry among migrant and German children: a cross-sectional study
Will B, Zeeb H, Baune BT. Overweight and obesity at school entry among migrant and German children: a cross-sectional study. BMC Public Health. 2005;5(1): 45.BACKGROUND: Overweight and obesity have become a global epidemic and are increasing rapidly in both childhood and adolescence. Obesity is linked both to socioeconomic status and to ethnicity among adults. It is unclear whether similar associations exist in childhood. The aim of the present study was to assess differences in overweight and obesity in migrant and German children at school entry. METHODS: The body mass index (BMI) was calculated for 525 children attending the 2002 compulsory pre-school medical examinations in 12 schools in Bielefeld, Germany. We applied international BMI cut off points for overweight and obesity by sex and age. The migration status of children was based on sociodemographic data obtained from parents who were interviewed separately. RESULTS: The overall prevalence of overweight in children aged 6-7 was 11.9% (overweight incl. obesity), the obesity prevalence was 2.5%. The prevalence of overweight and obesity was higher for migrant children (14.7% and 3.1%) than for German children (9.1% and 1.9%). When stratified by parental social status, migrant children had a significantly higher prevalence of overweight than German children in the highest social class. (27.6% vs. 10.0%, p = 0.032) Regression models including country/region and socioeconomic status as independent variables indicated similar results. The patterns of overweight among migrant children differed only slightly depending on duration of stay of their family in Germany. CONCLUSION: Our data indicate that children from ethnic minorities in Germany are more frequently overweight or obese than German children. Social class as well as family duration of stay after immigration influence the pattern of overweight and obesity in children at school entry
Differences in the carcinogenic evaluation of glyphosate between the International Agency for Research on Cancer (IARC) and the European Food Safety Authority (EFSA)
The International Agency for Research on Cancer (IARC) Monographs Programme identifies chemicals, drugs, mixtures, occupational exposures, lifestyles and personal habits, and physical and biological agents that cause cancer in humans and has evaluated about 1000 agents since 1971. Monographs are written by ad hoc Working Groups (WGs) of international scientific experts over a period of about 12 months ending in an eight-day meeting. The WG evaluates all of the publicly available scientific information on each substance and, through a transparent and rigorous process,1 decides on the degree to which the scientific evidence supports that substance's potential to cause or not cause cancer in humans. For Monograph 112,2 17 expert scientists evaluated the carcinogenic hazard for four insecticides and the herbicide glyphosate.3 The WG concluded that the data for glyphosate meet the criteria for classification as a probable human carcinogen. The European Food Safety Authority (EFSA) is the primary agency of the European Union for risk assessments regarding food safety. In October 2015, EFSA reported4 on their evaluation of the Renewal Assessment Report5 (RAR) for glyphosate that was prepared by the Rapporteur Member State, the German Federal Institute for Risk Assessment (BfR). EFSA concluded that ?glyphosate is unlikely to pose a carcinogenic hazard to humans and the evidence does not support classification with regard to its carcinogenic potential?. Addendum 1 (the BfR Addendum) of the RAR5 discusses the scientific rationale for differing from the IARC WG conclusion. Serious flaws in the scientific evaluation in the RAR incorrectly characterise the potential for a carcinogenic hazard from exposure to glyphosate. Since the RAR is the basis for the European Food Safety Agency (EFSA) conclusion,4 it is critical that these shortcomings are corrected
Depressive symptoms in higher education students during the first wave of the COVID-19 pandemic. An examination of the association with various social risk factors across multiple high- and middle-income countries
Awareness and knowledge of sexually transmitted diseases (STDs) among school-going adolescents in Europe: a systematic review of published literature
Samkange-Zeeb FN, Spallek L, Zeeb H. Awareness and knowledge of sexually transmitted diseases (STDs) among school-going adolescents in Europe: a systematic review of published literature. BMC public health. 2011;11(1): 727.BACKGROUND: Sexually transmitted diseases (STDs) are a major health problem affecting mostly young people, not only in developing, but also in developed countries.We conducted this systematic review to determine awareness and knowledge of school-going male and female adolescents in Europe of STDs and if possible, how they perceive their own risk of contracting an STD. Results of this review can help point out areas where STD risk communication for adolescents needs to be improved. METHODS: Using various combinations of the terms "STD", "HIV", "HPV", "Chlamydia", "Syphilis", "Gonorrhoea", "herpes", "hepatitis B", "knowledge", "awareness", and "adolescents", we searched for literature published in the PubMed database from 01.01.1990 up to 31.12.2010. Studies were selected if they reported on the awareness and/or knowledge of one or more STD among school-attending adolescents in a European country and were published in English or German. Reference lists of selected publications were screened for further publications of interest. Information from included studies was systematically extracted and evaluated. RESULTS: A total of 15 studies were included in the review. All were cross-sectional surveys conducted among school-attending adolescents aged 13 to 20 years. Generally, awareness and knowledge varied among the adolescents depending on gender.Six STDs were focussed on in the studies included in the review, with awareness and knowledge being assessed in depth mainly for HIV/AIDS and HPV, and to some extent for chlamydia. For syphilis, gonorrhoea and herpes only awareness was assessed. Awareness was generally high for HIV/AIDS (above 90%) and low for HPV (range 5.4%-66%). Despite knowing that use of condoms helps protect against contracting an STD, some adolescents still regard condoms primarily as an interim method of contraception before using the pill. CONCLUSION: In general, the studies reported low levels of awareness and knowledge of sexually transmitted diseases, with the exception of HIV/AIDS. Although, as shown by some of the findings on condom use, knowledge does not always translate into behaviour change, adolescents' sex education is important for STD prevention, and the school setting plays an important role. Beyond HIV/AIDS, attention should be paid to infections such as chlamydia, gonorrhoea and syphilis
Assessment of potential effects of the electromagnetic fields of mobile phones on hearing
BACKGROUND: Mobile phones have become indispensable as communication tools; however, to date there is only a limited knowledge about interaction between electromagnetic fields (EMF) emitted by mobile phones and auditory function. The aim of the study was to assess potential changes in hearing function as a consequence of exposure to low-intensity EMF's produced by mobile phones at frequencies of 900 and 1800 MHz. METHODS: The within-subject study was performed on thirty volunteers (age 18–30 years) with normal hearing to assess possible acute effect of EMF. Participants attended two sessions: genuine and sham exposure of EMF. Hearing threshold levels (HTL) on pure tone audiometry (PTA) and transient evoked otoacoustic emissions (TEOAE's) were recorded before and immediately after 10 min of genuine and/or sham exposure of mobile phone EMF. The administration of genuine or sham exposure was double blind and counterbalanced in order. RESULTS: Statistical analysis revealed no significant differences in the mean HTLs of PTA and mean shifts of TEOAE's before and after genuine and/or sham mobile phone EMF 10 min exposure. The data collected showed that average TEOAE levels (averaged across a frequency range) changed less than 2.5 dB between pre- and post-, genuine and sham exposure. The greatest individual change was 10 dB, with a decrease in level from pre- to post- real exposure. CONCLUSION: It could be concluded that a 10-min close exposure of EMFs emitted from a mobile phone had no immediate after-effect on measurements of HTL of PTA and TEOAEs in young human subjects and no measurable hearing deterioration was detected in our study
Influence of the Stability of a Fused Protein and Its Distance to the Amyloidogenic Segment on Fibril Formation
Conversion of native proteins into amyloid fibrils is irreversible and therefore it is difficult to study the interdependence of conformational stability and fibrillation by thermodynamic analyses. Here we approached this problem by fusing amyloidogenic poly-alanine segments derived from the N-terminal domain of the nuclear poly (A) binding protein PABPN1 with a well studied, reversibly unfolding protein, CspB from Bacillus subtilis. Earlier studies had indicated that CspB could maintain its folded structure in fibrils, when it was separated from the amyloidogenic segment by a long linker. When CspB is directly fused with the amyloidogenic segment, it unfolds because its N-terminal chain region becomes integrated into the fibrillar core, as shown by protease mapping experiments. Spacers of either 3 or 16 residues between CspB and the amyloidogenic segment were not sufficient to prevent this loss of CspB structure. Since the low thermodynamic stability of CspB (ΔGD = 12.4 kJ/mol) might be responsible for unfolding and integration of CspB into fibrils, fusions with a CspB mutant with enhanced thermodynamic stability (ΔGD = 26.9 kJ/mol) were studied. This strongly stabilized CspB remained folded and prevented fibril formation in all fusions. Our data show that the conformational stability of a linked, independently structured protein domain can control fibril formation
How sharing can contribute to more sustainable cities
\ua9 2017 by the authors. Recently, much of the literature on sharing in cities has focused on the sharing economy, in which people use online platforms to share underutilized assets in the marketplace. This view of sharing is too narrow for cities, as it neglects the myriad of ways, reasons, and scales in which citizens share in urban environments. Research presented here by the Liveable Cities team in the form of participant workshops in Lancaster and Birmingham, UK, suggests that a broader approach to understanding sharing in cities is essential. The research also highlighted tools and methods that may be used to help to identify sharing in communities. The paper ends with advice to city stakeholders, such as policymakers, urban planners, and urban designers, who are considering how to enhance sustainability in cities through sharing
How well do adolescents recall use of mobile telephones? Results of a validation study
<p>Abstract</p> <p>Background</p> <p>In the last decade mobile telephone use has become more widespread among children. Concerns expressed about possible health risks have led to epidemiological studies investigating adverse health outcomes associated with mobile telephone use. Most epidemiological studies have relied on self reported questionnaire responses to determine individual exposure. We sought to validate the accuracy of self reported adolescent mobile telephone use.</p> <p>Methods</p> <p>Participants were recruited from year 7 secondary school students in Melbourne, Australia. Adolescent recall of mobile telephone use was assessed using a self administered questionnaire which asked about number and average duration of calls per week. Validation of self reports was undertaken using Software Modified Phones (SMPs) which logged exposure details such as number and duration of calls.</p> <p>Results</p> <p>A total of 59 adolescents participated (39% boys, 61% girls). Overall a modest but significant rank correlation was found between self and validated number of voice calls (ρ = 0.3, P = 0.04) with a sensitivity of 57% and specificity of 66%. Agreement between SMP measured and self reported duration of calls was poorer (ρ = 0.1, P = 0.37). Participants whose parents belonged to the 4<sup>th </sup>socioeconomic stratum recalled mobile phone use better than others (ρ = 0.6, P = 0.01).</p> <p>Conclusion</p> <p>Adolescent recall of mobile telephone use was only modestly accurate. Caution is warranted in interpreting results of epidemiological studies investigating health effects of mobile phone use in this age group.</p
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