3,954 research outputs found
Direct determination of the solar neutrino fluxes from solar neutrino data
We determine the solar neutrino fluxes from a global analysis of the solar
and terrestrial neutrino data in the framework of three-neutrino mixing. Using
a Bayesian approach we reconstruct the posterior probability distribution
function for the eight normalization parameters of the solar neutrino fluxes
plus the relevant masses and mixing, with and without imposing the luminosity
constraint. This is done by means of a Markov Chain Monte Carlo employing the
Metropolis-Hastings algorithm. We also describe how these results can be
applied to test the predictions of the Standard Solar Models. Our results show
that, at present, both models with low and high metallicity can describe the
data with good statistical agreement.Comment: 24 pages, 1 table, 7 figures. Acknowledgments correcte
The "Solar Model Problem" Solved by the Abundance of Neon in Stars of the Local Cosmos
The interior structure of the Sun can be studied with great accuracy using
observations of its oscillations, similar to seismology of the Earth. Precise
agreement between helioseismological measurements and predictions of
theoretical solar models has been a triumph of modern astrophysics (Bahcall et
al. 2005). However, a recent downward revision by 25-35% of the solar
abundances of light elements such as C, N, O and Ne (Asplund et al. 2004) has
broken this accordance: models adopting the new abundances incorrectly predict
the depth of the convection zone, the depth profiles of sound speed and
density, and the helium abundance (Basu Antia 2004, Bahcall et al. 2005). The
discrepancies are far beyond the uncertainties in either the data or the model
predictions (Bahcall et al. 2005b). Here we report on neon abundances relative
to oxygen measured in a sample of nearby solar-like stars from their X-ray
spectra. They are all very similar and substantially larger than the recently
revised solar value. The neon abundance in the Sun is quite poorly determined.
If the Ne/O abundance in these stars is adopted for the Sun the models are
brought back into agreement with helioseismology measurements (Antia Basu 2005,
Bahcall et al. 2005c).Comment: 13 pages, 3 Figure
Identification of a small molecule inhibitor of Ebolavirus genome replication and transcription using in silico screening.
Ebola virus (EBOV) causes a severe haemorrhagic fever in humans and has a mortality rate over 50%. With no licensed drug treatments available, EBOV poses a significant threat. Investigations into possible therapeutics have been severely hampered by the classification of EBOV as a BSL4 pathogen. Here, we describe a drug discovery pathway combining in silico screening of compounds predicted to bind to a hydrophobic pocket on the nucleoprotein (NP); with a robust and rapid EBOV minigenome assay for inhibitor validation at BSL2. One compound (MCCB4) was efficacious (EC50 4.8 μM), exhibited low cytotoxicity (CC50 > 100 μM) and was specific, with no effect on either a T7 RNA polymerase driven firefly luciferase or a Bunyamwera virus minigenome. Further investigations revealed that this small molecule inhibitor was able to outcompete established replication complexes, an essential aspect for a potential EBOV treatment
Combinatorial RNA Design: Designability and Structure-Approximating Algorithm
In this work, we consider the Combinatorial RNA Design problem, a minimal
instance of the RNA design problem which aims at finding a sequence that admits
a given target as its unique base pair maximizing structure. We provide
complete characterizations for the structures that can be designed using
restricted alphabets. Under a classic four-letter alphabet, we provide a
complete characterization of designable structures without unpaired bases. When
unpaired bases are allowed, we provide partial characterizations for classes of
designable/undesignable structures, and show that the class of designable
structures is closed under the stutter operation. Membership of a given
structure to any of the classes can be tested in linear time and, for positive
instances, a solution can be found in linear time. Finally, we consider a
structure-approximating version of the problem that allows to extend bands
(helices) and, assuming that the input structure avoids two motifs, we provide
a linear-time algorithm that produces a designable structure with at most twice
more base pairs than the input structure.Comment: CPM - 26th Annual Symposium on Combinatorial Pattern Matching, Jun
2015, Ischia Island, Italy. LNCS, 201
Lower urinary tract and bowel dysfunction in spinocerebellar ataxias
Background: Little information is available in spinocerebellar ataxias (SCAs)
regarding pelvic organ symptoms. The aim of this study was to characterize the
lower urinary tract (LUT) and bowel dysfunction in autosomal dominant
spinocerebellar ataxias. Methods: Patients with confirmed SCAs attending a tertiary care service were approached about LUT and bowel complaints, and completed validated questionnaires: urinary symptom profile (USP), QualiveenShort form, International Prostate Symptom Score, and Neurogenic Bowel Dysfunction Score. SCA3 and SCA7 patients with urological complaints additionally underwent urodynamic studies (UDS). Patients’ characterization included
demographic, clinical (Scale for the Assessment and Rating of Ataxia (SARA),
Inventory of Non-Ataxia Signs (INAS)), and genetic variables. Descriptive and
comparative analyses were performed. Results: Fifty-one patients participated:
SCA1 (n = 4), SCA2 (n = 11), SCA3 (n = 13), SCA6 (n = 17), and SCA7
(n = 6). The prevalence of self-reported LUT symptoms was 60.8% (n = 31),
whereas LUT symptoms was reported in 86.3%(n = 44) using the USP. Both
storage and voiding symptoms were reported, urinary frequency and urgency
being the most frequent (n = 34, 68%). Although LUT symptoms were most
often classed as mild (n = 27, 61.4%), they impacted QoL in 38 patients
(77.6%). Of these, 21 (55.3%) were not on pharmacological treatment for urinary dysfunction. Most common abnormalities in UDS (n = 14) were detrusor
overactivity (storage phase) and detrusor underactivity (voiding phase). Bowel
symptoms were less common (31.4%, n = 16) and of mild severity. Conclusion: LUT symptoms are prevalent in SCA patients and impact QoL, whereas
bowel symptoms tend to be mild. These symptoms are overlooked by patients
and physicians due to the complexity of neurological involvement in SCA, and
therefore a multidisciplinary management approach should be adopted
Evidence-informed health policy 3 – Interviews with the directors of organizations that support the use of research evidence
Background: Previous surveys of organizations that support the development of evidence-informed health policies have focused on organizations that produce clinical practice guidelines (CPGs) or undertake health technology assessments (HTAs). Only rarely have surveys focused at least in part on units that directly support the use of research evidence in developing health policy on an international, national, and state or provincial level (i.e., government support units, or GSUs) that are in some way successful or innovative or that support the use of research evidence in low- and middle-income countries (LMICs). Methods: We drew on many people and organizations around the world, including our project reference group, to generate a list of organizations to survey. We modified a questionnaire that had been developed originally by the Appraisal of Guidelines, Research and Evaluation in Europe (AGREE) collaboration and adapted one version of the questionnaire for organizations producing CPGs and HTAs, and another for GSUs. We sent the questionnaire by email to 176 organizations and followed up periodically with non-responders by email and telephone. Results: We received completed questionnaires from 152 (86%) organizations. More than one-half of the organizations (and particularly HTA agencies) reported that examples from other countries were helpful in establishing their organization. A higher proportion of GSUs than CPG-or HTA-producing organizations involved target users in the selection of topics or the services undertaken. Most organizations have few (five or fewer) full-time equivalent (FTE) staff. More than four-fifths of organizations reported providing panels with or using systematic reviews. GSUs tended to use a wide variety of explicit valuation processes for the research evidence, but none with the frequency that organizations producing CPGs, HTAs, or both prioritized evidence by its quality. Between one-half and two-thirds of organizations do not collect data systematically about uptake, and roughly the same proportions do not systematically evaluate their usefulness or impact in other ways. Conclusion: The findings from our survey, the most broadly based of its kind, both extend or clarify the applicability of the messages arising from previous surveys and related documentary analyses, such as how the 'principles of evidence-based medicine dominate current guideline programs' and the importance of collaborating with other organizations. The survey also provides a description of the history, structure, processes, outputs, and perceived strengths and weaknesses of existing organizations from which those establishing or leading similar organizations can draw
SUPPORT Tools for evidence-informed Policymaking in health 11: Finding and using evidence about local conditions
This article is part of a series written for people responsible for making decisions about health policies and programmes and for those who support these decision makers
Shape Analysis and Computational Fluid Simulations to Assess Feline Left Atrial Function and Thrombogenesis
In humans, there is a well-established relationship between atrial fibrillation (AF), blood flow abnormalities and thrombus formation, even if there is no clear consensus on the role of left atrial appendage (LAA) morphologies. Cats can also suffer heart diseases, often leading to an enlargement of the left atrium that promotes stagnant blood flow, activating the clotting process and promoting feline aortic thromboembolism. The majority of pathological feline hearts have echocardiographic evidence of abnormal left ventricular filling, usually assessed with 2D and Doppler echocardiography and standard imaging tools. Actually, veterinary professionals have limited access to advanced computational techniques that would enable a better understanding of feline heart pathologies with improved morphological and haemodynamic descriptors. In this work, we applied state-of-the-art image processing and computational fluid simulations based on micro-computed tomography images acquired in 24 cases, including normal cats and cats with varying severity of cardiomyopathy. The main goal of the study was to identify differences in the LA/LAA morphologies and blood flow patterns in the analysed cohorts with respect to thrombus formation and cardiac pathology. The obtained results show significant differences between normal and pathological feline hearts, as well as in thrombus vs non-thrombus cases and asymptomatic vs symptomatic cases, while it was not possible to discern in congestive heart failure with thrombus and from non-thrombus cases. Additionally, in-silico fluid simulations demonstrated lower LAA blood flow velocities and higher thrombotic risk in the thrombus cases
Spontaneous R-Parity Violation, Flavor Symmetry and Tribimaximal Mixing
We explore the possibility of spontaneous R parity violation in the context
of flavor symmetry. Our model contains singlet matter chiral superfields which are arranged as triplet of
and as well as few additional Higgs chiral superfields which are singlet
under MSSM gauge group and belong to triplet and singlet representation under
the flavor symmetry. R parity is broken spontaneously by the vacuum
expectation values of the different sneutrino fields and hence we have
neutrino-neutralino as well as neutrino-MSSM gauge singlet higgsino mixings in
our model, in addition to the standard model neutrino- gauge singlet neutrino,
gaugino-higgsino and higgsino-higgsino mixings. Because all of these mixings we
have an extended neutral fermion mass matrix. We explore the low energy
neutrino mass matrix for our model and point out that with some specific
constraints between the sneutrino vacuum expectation values as well as the MSSM
gauge singlet Higgs vacuum expectation values, the low energy neutrino mass
matrix will lead to a tribimaximal mixing matrix. We also analyze the potential
minimization for our model and show that one can realize a higher vacuum
expectation value of the singlet
sneutrino fields even when the other sneutrino vacuum expectation values are
extremely small or even zero.Comment: 18 page
- …