114,114 research outputs found
Looking for a gift of Nature: Hadron loops and hybrid mixing
We investigate how coupling of valence q qbar to meson pairs can modify the
properties of conventional q qbar and hybrid mesons. In a symmetry limit the
mixing between hybrids and conventional q qbar with the same J^PC is shown to
vanish. Flavor mixing between heavy and light q qbar due to meson loops is
shown to be dual to the results of gluon mediated pQCD, and qualitatively
different from mixing involving light flavors alone. The validity of the OZI
rule for conventional q qbar and hybrid mesons is discussed.Comment: v2: added important references and discussion of previous literature;
results and conclusions unchanged. 8 pages, 2 figure
Siphonaptera Records and Host Associations From the Central and Eastern Upper Peninsula of Michigan
Fleas were collected from birds and mammals over a five year period in four upper peninsula counties. Identified specimens were compared to published records of distribution for the parasite species and its host species, and only those records which are new county distributions for host or parasite are listed. Four new host records for Michigan, four new flea distribution records for the upper peninsula, and 26 new county records are listed
Ambient connections realising conformal Tractor holonomy
For a conformal manifold we introduce the notion of an ambient connection, an
affine connection on an ambient manifold of the conformal manifold, possibly
with torsion, and with conditions relating it to the conformal structure. The
purpose of this construction is to realise the normal conformal tractor
holonomy as affine holonomy of such a connection. We give an example of an
ambient connection for which this is the case, and which is torsion free if we
start the construction with a C-space, and in addition Ricci-flat if we start
with an Einstein manifold. Thus for a -space this example leads to an
ambient metric in the weaker sense of \v{C}ap and Gover, and for an Einstein
space to a Ricci-flat ambient metric in the sense of Fefferman and Graham.Comment: 17 page
Impact and Cost-Effectiveness of Point-Of-Care CD4 Testing on the HIV Epidemic in South Africa.
Rapid diagnostic tools have been shown to improve linkage of patients to care. In the context of infectious diseases, assessing the impact and cost-effectiveness of such tools at the population level, accounting for both direct and indirect effects, is key to informing adoption of these tools. Point-of-care (POC) CD4 testing has been shown to be highly effective in increasing the proportion of HIV positive patients who initiate ART. We assess the impact and cost-effectiveness of introducing POC CD4 testing at the population level in South Africa in a range of care contexts, using a dynamic compartmental model of HIV transmission, calibrated to the South African HIV epidemic. We performed a meta-analysis to quantify the differences between POC and laboratory CD4 testing on the proportion linking to care following CD4 testing. Cumulative infections averted and incremental cost-effectiveness ratios (ICERs) were estimated over one and three years. We estimated that POC CD4 testing introduced in the current South African care context can prevent 1.7% (95% CI: 0.4% - 4.3%) of new HIV infections over 1 year. In that context, POC CD4 testing was cost-effective 99.8% of the time after 1 year with a median estimated ICER of US$4,468/DALY averted. In healthcare contexts with expanded HIV testing and improved retention in care, POC CD4 testing only became cost-effective after 3 years. The results were similar when, in addition, ART was offered irrespective of CD4 count, and CD4 testing was used for clinical assessment. Our findings suggest that even if ART is expanded to all HIV positive individuals and HIV testing efforts are increased in the near future, POC CD4 testing is a cost-effective tool, even within a short time horizon. Our study also illustrates the importance of evaluating the potential impact of such diagnostic technologies at the population level, so that indirect benefits and costs can be incorporated into estimations of cost-effectiveness
Some Constraints On the Effects of Age and Metallicity on the Low Mass X-ray Binary Formation Rate
We have studied the low mass X-ray binary (LMXB) populations within and
outside globular clusters (GC) in NGC 4365 and NGC 3115. Using published age
and metallicity constraints from optical and IR observations of their GCs, we
do not find any evidence for an increase in the LMXB formation rate in the
intermediate age cluster population of NGC 4365, as has been proposed in some
scenarios of dynamical LMXB formation in GCs. The old, metal-rich, red
population of GCs in NGC 3115 on the other hand is {\it at least} three times
as efficient at creating LMXBs as the old, metal-poor, blue clusters. These
data suggest that the higher formation efficiency of LMXBs in the red GC
subsystems of many galaxies is largely a consequence of their higher
metallicity. A comparison of the densities of field LMXBs in different galaxies
does not reveal an obvious correlation with the age of the field stars as
predicted by models in which the LMXB formation rate in the field drops
monotonically with time after an initial burst. This suggests that either a
significant fraction of the field LMXBs are created in GCs and subsequently
injected into the field, or the LMXB formation rate has a more complex time
evolution pattern.Comment: Accepted for publication in ApJ Letters. 7 pages including 5 figure
One qubit almost completely reveals the dynamics of two
From the time dependence of states of one of them, the dynamics of two
interacting qubits is determined to be one of two possibilities that differ
only by a change of signs of parameters in the Hamiltonian. The only exception
is a simple particular case where several parameters in the Hamiltonian are
zero and one of the remaining nonzero parameters has no effect on the time
dependence of states of the one qubit. The mean values that describe the
initial state of the other qubit and of the correlations between the two qubits
also are generally determined to within a change of signs by the time
dependence of states of the one qubit, but with many more exceptions. An
example demonstrates all the results. Feedback in the equations of motion that
allows time dependence in a subsystem to determine the dynamics of the larger
system can occur in both classical and quantum mechanics. The role of quantum
mechanics here is just to identify qubits as the simplest objects to consider
and specify the form that equations of motion for two interacting qubits can
take.Comment: 6 pages with new and updated materia
Direct Injection Liquid Chromatography High-Resolution Mass Spectrometry for Determination of Primary and Secondary Terrestrial and Marine Biomarkers in Ice Cores
Many atmospheric organic compounds are long-lived enough to be transported from their sources to polar regions and high mountain environments where they can be trapped in ice archives. While inorganic components in ice archives have been studied extensively to identify past climate changes, organic compounds have rarely been used to assess paleo-environmental changes, mainly due to the lack of suitable analytical methods. This study presents a new method of direct injection HPLC-MS analysis, without the need of pre-concentrating the melted ice, for the determination of a series of novel biomarkers in ice-core samples indicative of primary and secondary terrestrial and marine organic aerosol sources. Eliminating a preconcentration step reduces contamination potential and decreases the required sample volume thus allowing a higher time resolution in the archives. The method is characterised by limits of detections (LODs) in the range of 0.01-15 ppb, depending on the analyte, and accuracy evaluated through an interlaboratory comparison. We find that many components in secondary organic aerosols (SOA) are clearly detectable at concentrations comparable to those previously observed in replicate preconcentrated ice samples from the Belukha glacier, Russian Altai Mountains. Some compounds with low recoveries in preconcentration steps are now detectable in samples with this new direct injection method significantly increasing the range of environmental processes and sources that become accessible for paleo-climate studies
Effectiveness of continence promotion for older women via community organisations: A cluster randomised trial
This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/3.0/Objectives: The primary objective of this cluster randomised controlled trial was to compare the effectiveness of the three experimental continence promotion interventions against a control intervention on urinary symptom improvement in older women with untreated incontinence recruited from community organisations. A second objective was to determine whether changes in incontinence-related knowledge and new uptake of risk-modifying behaviours explain these improvements.
Setting: 71 community organisations across the UK.
Participants: 259 women aged 60 years and older with untreated incontinence entered the trial; 88% completed the 3-month follow-up.
Interventions: The three active interventions consisted of a single 60 min group workshop on (1) continence education (20 clusters, 64 women); (2) evidence-based self-management (17 clusters, 70 women); or (3) combined continence education and self-management (17 clusters, 61 women). The control intervention was a single 60 min educational group workshop on memory loss, polypharmacy and osteoporosis (17 clusters, 64 women).
Primary and secondary outcome measures: The primary outcome was self-reported improvement in incontinence 3 months postintervention at the level of the individual. The secondary outcome was change in the International Consultation on Incontinence Questionnaire (ICIQ) from baseline to 3-month follow-up. Changes in incontinence-related knowledge and behaviours were also assessed.
Results: The highest rate of urinary symptom improvement occurred in the combined intervention group (66% vs 11% of the control group, prevalence difference 55%, 95% CI 43% to 67%, intracluster correlation 0). 30% versus 6% of participants reported significant improvement respectively (prevalence difference 23%, 95% CI 10% to 36%, intracluster correlation 0). The number-needed-to-treat was 2 to achieve any improvement in incontinence symptoms, and 5 to attain significant improvement. Compared to controls, participants in the combined intervention reported an adjusted mean 2.05 point (95% CI 0.87 to 3.24) greater improvement on the ICIQ from baseline to 3-month follow-up. Changes in knowledge and self-reported risk-reduction behaviours paralleled rates of improvement in all intervention arms.
Conclusions: Continence education combined with evidence-based self-management improves symptoms of incontinence among untreated older women. Community organisations represent an untapped vector for delivering effective continence promotion interventions.Canadian Institutes of Health Research – Institute on
Aging and the Economic and Social Research Council (UK
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