441 research outputs found
Leukemia, Brain Tumors, and Exposure to Extremely Low Frequency Electromagnetic Fields in Swiss Railway Employees
Railway engineers provide excellent opportunities for studying the relation between exposure to extremely low frequency magnetic fields and leukemia or brain tumors. In a cohort study of Swiss railway personnel with 2.7 Ă 105 person-years of follow-up (1972-1993), the authors compared occupations with high average exposures (line engineers: 25.9 ÎŒT) to those with medium and low exposures (station masters: 1 ÎŒT). The mortality rate ratio for leukemia was 2.4 (95% confidence interval (CI): 1.0, 6.1) among line engineers (reference category: station masters). The mortality rate ratio for brain tumors was 1.0 (95% CI: 0.2, 4.6) among line engineers and 5.1 (95% CI: 1.2, 21.2) among shunting yard engineers (compared with station masters). Two exposure characteristics were evaluated: cumulative exposure in ÎŒT-years and years spent under exposure to magnetic fields of â„10 ÎŒT. There was a significant increase in leukemia mortality of 0.9% (95% CI: 0.2, 1.7) per ÎŒT-year of cumulative exposure to extremely low frequency magnetic fields. The increase by years spent under exposure of â„10 ÎŒT was even stronger: 62% per year (95% CI: 15, 129). Brain cancer risk did not show a dose-response relation. This study contributes to the evidence for a link between heavy exposure to extremely low frequency magnetic fields and leukemia. Its strengths include reliable measurements and reliable historical reconstruction of exposure
Culture, risk factors and mortality: can Switzerland add missing pieces to the European puzzle?
BACKGROUND: The aim was to compare cause-specific mortality, self-rated health (SRH) and risk factors in the French and German part of Switzerland and to discuss to what extent variations between these regions reflect differences between France and Germany. METHODS: Data were used from the general population of German and French Switzerland with 2.8 million individuals aged 45-74 years, contributing 176 782 deaths between 1990 and 2000. Adjusted mortality risks were calculated from the Swiss National Cohort, a longitudinal census-based record linkage study. Results were contrasted with cross-sectional analyses of SRH and risk factors (Swiss Health Survey 1992/3) and with cross-sectional national and international mortality rates for 1980, 1990 and 2000. RESULTS: Despite similar all-cause mortality, there were substantial differences in cause-specific mortality between Swiss regions. Deaths from circulatory disease were more common in German Switzerland, while causes related to alcohol consumption were more prevalent in French Switzerland. Many but not all of the mortality differences between the two regions could be explained by variations in risk factors. Similar patterns were found between Germany and France. CONCLUSION: Characteristic mortality and behavioural differentials between the German- and the French-speaking parts of Switzerland could also be found between Germany and France. However, some of the international variations in mortality were not in line with the Swiss regional comparison nor with differences in risk factors. These could relate to peculiarities in assignment of cause of death. With its cultural diversity, Switzerland offers the opportunity to examine cultural determinants of mortality without bias due to different statistical systems or national health policies
The Bradyrhizobium japonicum phoB gene is required for phosphate-limited growth but not for symbiotic nitrogen fixation
We identified by cloning and DNA sequence analysis the phosphate regulatory gene phoB of Bradyrhizobium japonicum. The deduced gene product displayed pronounced similarity to the PhoB protein of Sinorhizobium meliloti (71.4% identical amino acids), Escherichia coli (50.2%) and other bacterial species. Insertion of a kanamycin resistance cassette into phoB led to impaired growth of the B. japonicum mutant in media containing approximately 25 ÎŒM phosphate or less. A standard plant infection test using wild-type and phoB-defective B. japonicum strains showed that the phoB mutation had no effect on the symbiotic properties of B. japonicum with its soybean host plan
Crystal structure of the human ATP-dependent splicing and export factor UAP56
Pre-mRNA splicing requires the function of a number of RNA-dependent ATPases/helicases, yet no three-dimensional structure of any spliceosomal ATPases/helicases is known. The highly conserved DECD-box protein UAP56/Sub2 is an essential splicing factor that is also important for mRNA export. The expected ATPase/helicase activity appears to be essential for the UAP56/Sub2 functions. Here, we show that purified human UAP56 is an active RNA-dependent ATPase, and we also report the crystal structures of UAP56 alone and in complex with ADP, as well as a DECD to DEAD mutant. The structures reveal a unique spatial arrangement of the two conserved helicase domains, and ADP-binding induces significant conformational changes of key residues in the ATP-binding pocket. Our structural analyses suggest a specific protein-RNA displacement model of UAP56/Sub2. The detailed structural information provides important mechanistic insights into the splicing function of UAP56/Sub2. The structures also will be useful for the analysis of other spliceosomal DExD-box ATPases/helicases
Superconductivity enhanced conductance fluctuations in few layer graphene nanoribbons
We investigate the mesoscopic disorder induced rms conductance variance
in a few layer graphene nanoribbon (FGNR) contacted by two
superconducting (S) Ti/Al contacts. By sweeping the back-gate voltage, we
observe pronounced conductance fluctuations superimposed on a linear background
of the two terminal conductance G. The linear gate-voltage induced response can
be modeled by a set of inter-layer and intra-layer capacitances.
depends on temperature T and source-drain voltage .
increases with decreasing T and . When lowering , a
pronounced cross-over at a voltage corresponding to the superconducting energy
gap is observed. For |V_{sd}|\ltequiv \Delta the fluctuations are
markedly enhanced. Expressed in the conductance variance of one
graphene-superconducutor (G-S) interface, values of 0.58 e^2/h are obtained at
the base temperature of 230 mK. The conductance variance in the sub-gap region
are larger by up to a factor of 1.4-1.8 compared to the normal state. The
observed strong enhancement is due to phase coherent charge transfer caused by
Andreev reflection at the nanoribbon-superconductor interface.Comment: 15 pages, 5 figure
Emotional and physical demands on caregivers in home care to the elderly in Switzerland and their relationship to nursing home admission
Background: Planning the home care of growing numbers of old, dependent people must include the caregivers' burden. Methods: A convenience sample of 129 caregivers of elderly patients with multiple diagnoses was interviewed about the caregiving context, burden, caregivers' tolerance of patients' troublesome behaviours and physical symptoms, mutuality and feelings of closeness between caregiver and patient. Continued maintenance of home care was assessed by a follow-up telephone call. Results: Caregivers were mainly spouses (67%) and female (73%), and the mean duration of care was 5.5 years. In five activities of daily living (ADL) 50-69% of the patients needed full help. Caregivers reported predominantly negative effects of caregiving on their physical and mental health, rest and sleep, leisure time and social life, problems with patients' symptoms and behaviours and little or no conversing (51%) or exchanging feelings with patients (71%). Predictive models: Contributors to variance were for burden (35%), impact of care on caregivers' mental health, social relations and leisure time, patients' gender, accumulation of patients' symptoms and behaviours; for caregivers' tolerance toward patients' symptoms and behaviours (17%) caregivers' physical health, patients' level of confusion, feelings of mutuality; for mutuality (22%) and for closeness (19%) caregivers' mental health, patients' accumulation of symptoms and behaviours. Within 23 months 19% of the patients had been institutionalized. Factors giving a higher likelihood of institutionalization were: being male, caregiver was not a partner, and less closeness between caregiver and patient. Conclusion: Caregiving of older persons has bio-psychosocial ramifications for caregivers. Closeness between caregiver and patient seems to be a key factor in determination of the long-term outcom
Using LDGM Codes and Sparse Syndromes to Achieve Digital Signatures
In this paper, we address the problem of achieving efficient code-based
digital signatures with small public keys. The solution we propose exploits
sparse syndromes and randomly designed low-density generator matrix codes.
Based on our evaluations, the proposed scheme is able to outperform existing
solutions, permitting to achieve considerable security levels with very small
public keys.Comment: 16 pages. The final publication is available at springerlink.co
Synthesizing a spin-dependent force for optical, metastable, and ground state trapped-ion qubits
A single bichromatic field near-resonant to a qubit transition is typically
used for or M{\o}lmer-S{\o}rensen type
interactions in trapped ion systems. Using this field configuration, we present
a novel scheme to synthesize a spin-dependent force instead;
this basis change merely requires adjusting the beat-note frequency of the
bichromatic field. We implement this scheme with a laser near-resonant to a
quadrupole transition in Sr. We characterise its robustness to
optical phase and qubit frequency offsets and demonstrate its versatility by
entangling optical, metastable, and ground state qubits.Comment: O. B\u{a}z\u{a}van and S. Saner contributed equally to this wor
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