2,395 research outputs found
Shocking Signals of Dark Matter Annihilation
We examine whether charged particles injected by self-annihilating Dark
Matter into regions undergoing Diffuse Shock Acceleration (DSA) can be
accelerated to high energies. We consider three astrophysical sites where shock
acceleration is supposed to occur, namely the Galactic Centre, galaxy clusters
and Active Galactic Nuclei (AGN). For the Milky Way, we find that the
acceleration of cosmic rays injected by dark matter could lead to a bump in the
cosmic ray spectrum provided that the product of the efficiency of the
acceleration mechanism and the concentration of DM particles is high enough.
Among the various acceleration sources that we consider (namely supernova
remnants (SNRs), Fermi bubbles and AGN jets), we find that the Fermi bubbles
are a potentially more efficient accelerator than SNRs. However both could in
principle accelerate electrons and protons injected by dark matter to very high
energies. At the extragalactic level, the acceleration of dark matter
annihilation products could be responsible for enhanced radio emission from
colliding clusters and prediction of an increase of the anti-deuteron flux
generated near AGNs.Comment: 9 pages, 4 figure
Electron microscopic visualization of tRNA genes with ferritin-avidin: biotin labels
A method is described for indirect electron microscopic visualization and mapping of tRNA and other short transcripts hybridized to DNA. This method depends upon the attachment of the electron-dense protein ferritin to the RNA, the binding being mediated by the remarkably strong association of the egg white protein avidin with biotin. Biotin is covalently attached to the 3' end of tRNA using an NH2 (CH2) 5NH2 bridge. The tRNA-biotin adduct is hybridized to complementcrry DNA sequences present in a single stranded nonhomology loop of a DNA:DNA heteroduplex. Avidin, covalently crosslinked to ferritin is mixed with the heteroduplex and becomes bound to the hybridized tRNA-biotin. Observation of the DNA:RNA-biotin:avidin-ferritin complex by electron microsdopy specifically and accurately reveals the position of the tRNA gene, with a frequency of labeling of approximately 50%
Preventing and lessening exacerbations of asthma in school-age children associated with a new term (PLEASANT) : Study protocol for a cluster randomised control trial
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedBackground: Within the UK, during September, there is a pronounced increase in the number of unscheduled medical contacts by school-aged children (4-16 years) with asthma. It is thought that that this might be caused by the return back to school after the summer holidays, suddenly mixing with other children again and picking up viruses which could affect their asthma. There is also a drop in the number of prescriptions administered in August. It is possible therefore that children might not be taking their medication as they should during the summer contributing to them becoming ill when they return to school. It is hoped that a simple intervention from the GP to parents of children with asthma at the start of the summer holiday period, highlighting the importance of maintaining asthma medication can help prevent increased asthma exacerbation, and unscheduled NHS appointments, following return to school in September.Methods/design: PLEASANT is a cluster randomised trial. A total of 140 General Practices (GPs) will be recruited into the trial; 70 GPs randomised to the intervention and 70 control practices of "usual care" An average practice is expected to have approximately 100 children (aged 4-16 with a diagnosis of asthma) hence observational data will be collected on around 14000 children over a 24-month period. The Clinical Practice Research Datalink will collect all data required for the study which includes diagnostic, prescription and referral data.Discussion: The trial will assess whether the intervention can reduce exacerbation of asthma and unscheduled medical contacts in school-aged children associated with the return to school after the summer holidays. It has the potential to benefit the health and quality of life of children with asthma while also improving the effectiveness of NHS services by reducing NHS use in one of the busiest months of the year. An exploratory health economic analysis will gauge any cost saving associated with the intervention and subsequent impacts on quality of life. If results for the intervention are positive it is hoped that this could be adopted as part of routine care management of childhood asthma in general practice. Trial registration: Current controlled trials: ISRCTN03000938 (assigned 19/10/12) http://www.controlled-trials.com/ISRCTN03000938/.UKCRN ID: 13572.Peer reviewe
Governor Ryan\u27s Capital Punishment Moratorium and the Executioner\u27s Confession: Views from the Governor\u27s Mansion to Death Row
Analysis of environmental influences in nuclear half-life measurements exhibiting time-dependent decay rates
In a recent series of papers evidence has been presented for correlations
between solar activity and nuclear decay rates. This includes an apparent
correlation between Earth-Sun distance and data taken at Brookhaven National
Laboratory (BNL), and at the Physikalisch-Technische Bundesanstalt (PTB).
Although these correlations could arise from a direct interaction between the
decaying nuclei and some particles or fields emanating from the Sun, they could
also represent an "environmental" effect arising from a seasonal variation of
the sensitivities of the BNL and PTB detectors due to changes in temperature,
relative humidity, background radiation, etc. In this paper, we present a
detailed analysis of the responses of the detectors actually used in the BNL
and PTB experiments, and show that sensitivities to seasonal variations in the
respective detectors are likely too small to produce the observed fluctuations
Open-label, cluster randomised controlled trial and economic evaluation of a brief letter from a GP on unscheduled medical contacts associated with the start of the school year: the PLEASANT trial
BACKGROUND: Asthma is seasonal with peaks in exacerbation rates in school-age children associated with the return to school following the summer vacation. A drop in prescription collection in August is associated with an increase in the number of unscheduled contacts after the school return. OBJECTIVE: To assess whether a public health intervention delivered in general practice reduced unscheduled medical contacts in children with asthma. DESIGN: Cluster randomised trial with trial-based economic evaluation. Randomisation was at general practice level, stratified by size of practice. The intervention group received a letter from their general practitioner (GP) in late July outlining the importance of (re)taking asthma medication before the return to school. The control group was usual care. SETTING: General practices in England and Wales. PARTICIPANTS: 12 179 school-age children in 142 general practices (70 randomised to intervention). MAIN OUTCOME: Proportion of children aged 5-16 years who had an unscheduled contact in September. Secondary endpoints included collection of prescriptions in August and medical contacts over 12 months (September-August). Economic endpoints were quality-adjusted life-years gained and health service costs. RESULTS: There was no evidence of effect (OR 1.09; 95% CI 0.96 to 1.25 against treatment) on unscheduled contacts in September. The intervention increased the proportion of children collecting a prescription in August by 4% (OR 1.43; 95% CI 1.24 to 1.64). The intervention also reduced the total number of medical contacts between September-August by 5% (incidence ratio 0.95; 95% CI 0.91 to 0.99).The mean reduction in medical contacts informed the health economics analyses. The intervention was estimated to save £36.07 per patient, with a high probability (96.3%) of being cost-saving. CONCLUSIONS: The intervention succeeded in increasing children collecting prescriptions. It did not reduce unscheduled care in September (the primary outcome), but in the year following the intervention, it reduced the total number of medical contacts. TRIAL REGISTRATION NUMBER: ISRCTN03000938; Results
Risk Factors for Diarrhea in Children Under Five Years of Age Residing in Peri-Urban Communities in Cochabamba, Bolivia
This study examined the relationship between childhood diarrhea prevalence and caregiver knowledge of the causes and prevention of diarrhea in a prospective cohort of 952 children \u3c 5 years of age in Cochabamba, Bolivia. The survey of caregiver knowledge found that more than 80% of caregivers were unaware that hand washing with soap could prevent childhood diarrhea. Furthermore, when asked how to keep food safe for children to eat only 17% of caregivers reported hand washing before cooking and feeding a child. Lack of caregiver awareness of the importance of practices related to hygiene and sanitation for diarrhea prevention were significant risk factors for diarrheal disease in this cohort. The knowledge findings from this study suggest that health promotion in these communities should put further emphasis on increasing knowledge of how water treatment, hand washing with soap, proper disposal of child feces, and food preparation relate to childhood diarrhea prevention
Electronic Structure of the Cuprate Superconducting and Pseudogap Phases from Spectroscopic Imaging STM
We survey the use of spectroscopic imaging STM to probe the electronic
structure of underdoped cuprates. Two distinct classes of electronic states are
observed in both the d-wave superconducting (dSC) and the pseudogap (PG)
phases. The first class consists of the dispersive Bogoliubov quasiparticle
excitations of a homogeneous d-wave superconductor, existing below a lower
energy scale E=Delta0. We find that the Bogoliubov quasiparticle interference
signatures of delocalized Cooper pairing are restricted to a k-space arc which
terminates near the lines connecting k=\pm(pi/a0,0) to k=\pm(pi/a0). This arc
shrinks continuously with decreasing hole density such that Luttinger's theorem
could be satisfied if it represents the front side of a hole-pocket which is
bounded behind by the lines between k=\pm(pi/a0,0) and k=\pm(0,pi/a0). In both
phases the only broken symmetries detected for the |E|<Delta0 states are those
of a d-wave superconductor. The second class of states occurs proximate to the
pseudogap energy scale E=Delta1. Here the non-dispersive electronic structure
breaks the expected 90o-rotational symmetry of electronic structure within each
unit cell, at least down to 180o-rotational symmetry. This Q=0 electronic
symmetry breaking was first detected as an electronic inequivalence at the two
oxygen sites within each unit cell by using a measure of nematic (C2) symmetry.
Incommensurate non-dispersive conductance modulations, locally breaking both
rotational and translational symmetries, coexist with this intra-unit-cell
electronic symmetry breaking at E=Delta1. Their characteristic wavevector Q is
determined by the k-space points where Bogoliubov quasiparticle interference
terminates and therefore changes continuously with doping. The distinct broken
electronic symmetry states (Q=0 and finite Q) coexisting at E~Delta1 are found
to be indistinguishable in the dSC and PG phases.Comment: 32 pages with 10 figure
Power Spectrum Analysis of Physikalisch-Technische Bundesanstalt Decay-Rate Data: Evidence for Solar Rotational Modulation
Evidence for an anomalous annual periodicity in certain nuclear decay data
has led to speculation concerning a possible solar influence on nuclear
processes. We have recently analyzed data concerning the decay rates of Cl-36
and Si-32, acquired at the Brookhaven National Laboratory (BNL), to search for
evidence that might be indicative of a process involving solar rotation.
Smoothing of the power spectrum by weighted-running-mean analysis leads to a
significant peak at frequency 11.18/yr, which is lower than the equatorial
synodic rotation rates of the convection and radiative zones. This article
concerns measurements of the decay rates of Ra-226 acquired at the
Physikalisch-Technische Bundesanstalt (PTB) in Germany. We find that a similar
(but not identical) analysis yields a significant peak in the PTB dataset at
frequency 11.21/yr, and a peak in the BNL dataset at 11.25/yr. The change in
the BNL result is not significant since the uncertainties in the BNL and PTB
analyses are estimated to be 0.13/yr and 0.07/yr, respectively. Combining the
two running means by forming the joint power statistic leads to a highly
significant peak at frequency 11.23/yr. We comment briefly on the possible
implications of these results for solar physics and for particle physics.Comment: 15 pages, 13 figure
Additional experimental evidence for a solar influence on nuclear decay rates
Additional experimental evidence is presented in support of the recent
hypothesis that a possible solar influence could explain fluctuations observed
in the measured decay rates of some isotopes. These data were obtained during
routine weekly calibrations of an instrument used for radiological safety at
The Ohio State University Research Reactor using Cl-36. The detector system
used was based on a Geiger-Mueller gas detector, which is a robust detector
system with very low susceptibility to environmental changes. A clear annual
variation is evident in the data, with a maximum relative count rate observed
in January/February, and a minimum relative count rate observed in July/August,
for seven successive years from July 2005 to June 2011. This annual variation
is not likely to have arisen from changes in the detector surroundings, as we
show here.Comment: 8 pages, 6 figure
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