5,662 research outputs found
Attosecond double-slit experiment
A new scheme for a double-slit experiment in the time domain is presented.
Phase-stabilized few-cycle laser pulses open one to two windows (``slits'') of
attosecond duration for photoionization. Fringes in the angle-resolved energy
spectrum of varying visibility depending on the degree of which-way information
are observed. A situation in which one and the same electron encounters a
single and a double slit at the same time is discussed. The investigation of
the fringes makes possible interferometry on the attosecond time scale. The
number of visible fringes, for example, indicates that the slits are extended
over about 500as.Comment: 4 figure
Public acceptability of financial incentives for smoking cessation in pregnancy and breastfeeding: a survey of the British public
Objective: To survey public attitudes about incentives for smoking cessation in pregnancy and for breast feeding to inform trial design.
Design: Cross-sectional survey. Setting and participants: British general public.
Methods: Seven promising incentive strategies had been identified from evidence syntheses and qualitative interview data from service users and providers. These were shopping vouchers for: (1) validated smoking cessation in pregnancy and (2) after birth; (3) for a smoke-free home; (4) for proven breast feeding; (5) a free breast pump; (6) payments to health services for reaching smoking cessation in pregnancy targets and (7) breastfeeding targets. Ipsos MORI used area quota sampling and home-administered computer-assisted
questionnaires, with randomised question order to assess agreement with different incentives (measured on a five-point scale). Demographic data and target behaviour experience were recorded. Analysis used multivariable ordered logit models.
Results: Agreement with incentives was mixed (ranging from 34% to 46%) among a representative sample of 1144 British adults. Mean agreement score was highest for a free breast pump, and lowest for incentives for smoking abstinence after birth. More women disagreed with shopping vouchers than men. Those with lower levels of education disagreed more
with smoking cessation incentives and a breast pump. Those aged 44 or under agreed more with all incentive strategies compared with those aged 65 and over, particularly provider targets for smoking cessation. Non-white ethnic groups agreed particularly with breastfeeding incentives. Current smokers with previous stop attempts and respondents who had breast fed children agreed with providing vouchers for
the respective behaviours. Up to £40/month vouchers for behaviour change were acceptable (>85%).
Conclusions: Women and the less educated were more likely to disagree, but men and women of childbearing age to agree, with incentives designed for their benefit. Trials evaluating reach, impact on health inequalities and ethnic groups are required prior to implementing incentive interventions
Systemic restoration of UBA1 ameliorates disease in spinal muscular atrophy
Acknowledgments Blood biochemistry analysis and serum analysis were performed by the Easter Bush Pathology Department, University of Edinburgh. Animal husbandry was performed by Centre for Integrative Physiology bio-research restructure technical staff, University of Edinburgh. Assistance with intravenous injections was provided by Ian Coldicott (University of Sheffield) and Hannah Shorrock (University of Edinburgh). Human blood cDNA was a gift to GH from Kathy Evans, University of Edinburgh. Imaging was performed at the IMPACT imaging facility, University of Edinburgh, with technical assistance from Anisha Kubasik-Thayil. The authors would also like to thank Lyndsay Murray for technical discussions relating to qRT-PCR analysis. This work was supported by funding from the SMA Trust and the Anatomical Society (via grants to THG); the Euan MacDonald Centre for Motor Neurone Disease Research (via grants to THG and SHP); the Wellcome Trust (via grants to EJNG and THG); Muscular Dystrophy UK (via grants to THG and CGB); a Elphinstone Scholarship from the University of Aberdeen (to SHP); and The French Muscular Dystrophy Association (via grants to CM and JC).Peer reviewedPublisher PD
Earth Matter Effects at Very Long Baselines and the Neutrino Mass Hierarchy
We study matter effects which arise in the muon neutrino oscillation and
survival probabilities relevant to atmospheric neutrino and very long baseline
beam experiments. The inter-relations between the three probabilities P_{\mu
e}, P_{\mu \tau} and P_{\mu \mu} are examined. It is shown that large and
observable sensitivity to the neutrino mass hierarchy can be present in P_{\mu
\mu} and P_{\mu \tau}. We emphasize that at baselines of > 7000 Km, matter
effects in P_{\mu \tau} can be large under certain conditions. The muon
survival rates in experiments with very long baselines thus depend on matter
effects in both P_{\mu \tau} and P_{\mu e}. We indicate where these effects are
sensitive to \theta_{13}, and identify ranges of E and L where the event rates
increase with decreasing \theta_{13}, providing a handle to probe small
\theta_{13}. The effect of parameter degeneracies in the three probabilities at
these baselines and energies is studied in detail. Realistic event rate
calculations are performed for a charge discriminating 100 kT iron calorimeter
which demonstrate the possibility of realising the goal of determining the
neutrino mass hierarchy using atmospheric neutrinos. It is shown that a careful
selection of energy and baseline ranges is necessary in order to obtain a
statistically significant signal, and that the effects are largest in bins
where matter effects in both P_{\mu e} and P_{\mu \tau} combine constructively.
Under these conditions, upto a 4\sigma signal for matter effects is possible
(for \Delta_{31}>0) within a timescale appreciably shorter than the one
anticipated for neutrino factories.Comment: 40 pages, 27 figures, version to match the published versio
Association of the IL2RA/CD25 Gene With Juvenile Idiopathic Arthritis
OBJECTIVE: IL2RA/CD25, the gene for interleukin-2 receptor alpha, is emerging as a general susceptibility gene for autoimmune diseases because of its role in the development and function of regulatory T cells and the association of single-nucleotide polymorphisms (SNPs) within this gene with type 1 diabetes mellitus (DM), Graves' disease, rheumatoid arthritis (RA), and multiple sclerosis (MS). The aim of this study was to determine whether SNPs within the IL2RA/CD25 gene are associated with juvenile idiopathic arthritis (JIA). METHODS: Three SNPs within the IL2RA/CD25 gene, that previously showed evidence of an association with either RA, MS, or type 1 DM, were selected for genotyping in UK JIA cases (n=654) and controls (n=3,849). Data for 1 SNP (rs2104286) were also available from North American JIA cases (n=747) and controls (n=1,161). Association analyses were performed using Plink software. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated. RESULTS: SNP rs2104286 within the IL2RA/CD25 gene was significantly associated with UK JIA cases (OR for the allele 0.76 [95% CI 0.66-0.88], P for trend=0.0002). A second SNP (rs41295061) also showed modest evidence for association with JIA (OR 0.80 [95% CI 0.63-1.0], P=0.05). Association with rs2104286 was convincingly replicated in the North American JIA cohort (OR 0.84 [95% CI 0.65-0.99], P for trend=0.05). Meta-analysis of the 2 cohorts yielded highly significant evidence of association with JIA (OR 0.76 [95% CI 0.62-0.88], P=4.9x10(-5)). CONCLUSION: These results provide strong evidence that the IL2RA/CD25 gene represents a JIA susceptibility locus. Further investigation of the gene using both genetic and functional approaches is now required
Intermittent dislocation flow in viscoplastic deformation
The viscoplastic deformation (creep) of crystalline materials under constant
stress involves the motion of a large number of interacting dislocations.
Analytical methods and sophisticated `dislocation-dynamics' simulations have
proved very effective in the study of dislocation patterning, and have led to
macroscopic constitutive laws of plastic deformation. Yet, a statistical
analysis of the dynamics of an assembly of interacting dislocations has not
hitherto been performed. Here we report acoustic emission measurements on
stressed ice single crystals, the results of which indicate that dislocations
move in a scale-free intermittent fashion. This result is confirmed by
numerical simulations of a model of interacting dislocations that successfully
reproduces the main features of the experiment. We find that dislocations
generate a slowly evolving configuration landscape which coexists with rapid
collective rearrangements. These rearrangements involve a comparatively small
fraction of the dislocations and lead to an intermittent behavior of the net
plastic response. This basic dynamical picture appears to be a generic feature
in the deformation of many other materials. Moreover, it should provide a
framework for discussing fundamental aspects of plasticity, that goes beyond
standard mean-field approaches that see plastic deformation as a smooth laminar
flow
Stationarity, soft ergodicity, and entropy in relativistic systems
Recent molecular dynamics simulations show that a dilute relativistic gas
equilibrates to a Juettner velocity distribution if ensemble velocities are
measured simultaneously in the observer frame. The analysis of relativistic
Brownian motion processes, on the other hand, implies that stationary
one-particle distributions can differ depending on the underlying
time-parameterizations. Using molecular dynamics simulations, we demonstrate
how this relativistic phenomenon can be understood within a deterministic model
system. We show that, depending on the time-parameterization, one can
distinguish different types of soft ergodicity on the level of the one-particle
distributions. Our analysis further reveals a close connection between time
parameters and entropy in special relativity. A combination of different
time-parameterizations can potentially be useful in simulations that combine
molecular dynamics algorithms with randomized particle creation, annihilation,
or decay processes.Comment: 4 page
Gravitational Microlensing Evidence for a Planet Orbiting a Binary Star System
The study of extra-solar planetary systems has emerged as a new discipline of
observational astronomy in the past few years with the discovery of a number of
extra-solar planets. The properties of most of these extra-solar planets were
not anticipated by theoretical work on the formation of planetary systems. Here
we report observations and light curve modeling of gravitational microlensing
event MACHO-97-BLG-41, which indicates that the lens system consists of a
planet orbiting a binary star system. According to this model, the mass ratio
of the binary star system is 3.8:1 and the stars are most likely to be a late K
dwarf and an M dwarf with a separation of about 1.8 AU. A planet of about 3
Jupiter masses orbits this system at a distance of about 7 AU. If our
interpretation of this light curve is correct, it represents the first
discovery of a planet orbiting a binary star system and the first detection of
a Jovian planet via the gravitational microlensing technique. It suggests that
giant planets may be common in short period binary star systems.Comment: 11 pages, with 1 color and 2 b/w Figures included (published version
CD30 Expression Reveals that Culture Adaptation of Human Embryonic Stem Cells Can Occur Through Differing Routes
Human embryonic stem cells undergo adaptive changes that can increase their growth capacity upon prolonged culture in vitro. This is frequently associated with nonrandom karyotypic changes, commonly involving amplification of genetic material from chromosomes 12, 17, and X. A recent study suggested that the karyotypically abnormal cells can be identified by their expression of CD30, which confers resistance to apoptosis. We have now investigated CD30 expression and apoptosis in karyotypically normal and abnormal sublines of the human ES cell line, H7, but our results were contrary to those previously observed. In this cell line, CD30 expression did not segregate the normal and abnormal cells, and abnormal cells were not protected from apoptosis. These data suggest that culture adaptation can occur through a variety of mechanisms
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