Bounds on isocurvature perturbations from CMB and LSS data

We obtain very stringent bounds on the possible cold dark matter, baryon and neutrino isocurvature contributions to the primordial fluctuations in the Universe, using recent cosmic microwave background and large scale structure data. In particular, we include the measured temperature and polarization power spectra from WMAP and ACBAR, as well as the matter power spectrum from the 2dF galaxy redshift survey. Neglecting the possible effects of spatial curvature, tensor perturbations and reionization, we perform a Bayesian likelihood analysis with nine free parameters, and find that the amplitude of the isocurvature component cannot be larger than about 31% for the cold dark matter mode, 91% for the baryon mode, 76% for the neutrino density mode, and 60% for the neutrino velocity mode, at 2-sigma, for uncorrelated models. On the other hand, for correlated adiabatic and isocurvature components, the fraction could be slightly larger. However, the cross-correlation coefficient is strongly constrained, and maximally correlated/anticorrelated models are disfavored. This puts strong bounds on the curvaton model, independently of the bounds on non-Gaussianity.Comment: 4 pages, 1 figure, some minor corrections; version accepted in PR

Optimization of the leak conductance in the squid giant axon

We report on a theoretical study showing that the leak conductance density, \GL, in the squid giant axon appears to be optimal for the action potential firing frequency. More precisely, the standard assumption that the leak current is composed of chloride ions leads to the result that the experimental value for \GL is very close to the optimal value in the Hodgkin-Huxley model which minimizes the absolute refractory period of the action potential, thereby maximizing the maximum firing frequency under stimulation by sharp, brief input current spikes to one end of the axon. The measured value of \GL also appears to be close to optimal for the frequency of repetitive firing caused by a constant current input to one end of the axon, especially when temperature variations are taken into account. If, by contrast, the leak current is assumed to be composed of separate voltage-independent sodium and potassium currents, then these optimizations are not observed.Comment: 9 pages; 9 figures; accepted for publication in Physical Review

Using audit and feedback to increase clinician adherence to clinical practice guidelines in brain injury rehabilitation: v

ObjectiveThis study evaluated whether frequent (fortnightly) audit and feedback cycles over a sustained period of time (>12 months) increased clinician adherence to recommended guidelines in acquired brain injury rehabilitation.DesignA before and after study design.SettingA metropolitan inpatient brain injury rehabilitation unit.ParticipantsClinicians; medical, nursing and allied health staff.InterventionsFortnightly cycles of audit and feedback for 14 months. Each fortnight, medical file and observational audits were completed against 114 clinical indicators.Main outcome measureAdherence to guideline indicators before and after intervention, calculated by proportions, Mann-Whitney U and Chi square analysis.ResultsClinical and statistical significant improvements in median clinical indicator adherence were found immediately following the audit and feedback program from 38.8% (95% CI 34.3 to 44.4) to 83.6% (95% CI 81.8 to 88.5). Three months after cessation of the intervention, median adherence had decreased from 82.3% to 76.6% (95% CI 72.7 to 83.3, pConclusionA fortnightly audit and feedback program increased clinicians’ adherence to guideline recommendations in an inpatient acquired brain injury rehabilitation setting. We propose future studies build on the evidence-based method used in the present study to determine effectiveness and develop an implementation toolkit for scale-up.</div

Does suprascapular nerve block reduce shoulder pain following stroke: a double-blind randomised controlled trial with masked outcome assessment

© 2010 Allen et al; licensee BioMed Central Ltd. 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 cited.Background Shoulder pain is a common complication of a stroke which can impede participation in rehabilitation programs and has been associated with poorer outcomes. The evidence base for current medical and therapeutic management options of hemiplegic shoulder pain is limited. This study will evaluate the use of suprascapular nerve block injection as part of an interdisciplinary approach to the treatment of shoulder pain following stroke. The technique has previously been proven safe and effective in the treatment of shoulder pain associated with rheumatoid arthritis and degenerative shoulder conditions but its usefulness in a stroke population is unclear. Methods/Design A double blind randomised placebo controlled trial will assess the effect of a suprascapular nerve block compared with placebo in a population of 66 stroke patients. The trial will measure effect of injection on the primary outcome of pain, and secondary outcomes of function and quality of life. Measurements will take place at baseline, and 1, 4 and 12 weeks post intervention. Both groups will continue to receive routine physiotherapy and standard ward care. Discussion The results of this study could reduce pain symptoms in persons with mechanical shoulder pain post stroke and provide improvement in upper limb function

Telerehabilitation services for stroke

Publisher version made available in accordance with the publisher's policy. This item is under embargo for a period of 12 months from the date of publication, in accordance with the publisher's policy. 'This review is published as a Cochrane Review in the Cochrane Database of Systematic Reviews 2013, Issue 12. Cochrane Reviews are regularly updated as new evidence emerges and in response to comments and criticisms, and the Cochrane Database of Systematic Reviews should be consulted for the most recent version of the Review.’Background Telerehabilitation is an alternative way of delivering rehabilitation services. Information and communication technologies are used to facilitate communication between the healthcare professional and the patient in a remote location. The use of telerehabilitation is becoming more viable as the speed and sophistication of communication technologies improve. However, it is currently unclear how effective this model of delivery is relative to rehabilitation delivered face-to-face. Objectives To determine whether the use of telerehabilitation leads to improved ability to perform activities of daily living amongst stroke survivors when compared with (1) in-person rehabilitation (when the clinician and the patient are at the same physical location and rehabilitation is provided face-to-face); or (2) no rehabilitation. Secondary objectives were to determine whether use of telerehabilitation leads to greater independence in self care and domestic life and improved mobility, health-related quality of life, upper limb function, cognitive function or functional communication when compared with in-person rehabilitation and no rehabilitation. Additionally, we aimed to report on the presence of adverse events, cost-effectiveness, feasibility and levels of user satisfaction associated with telerehabilitation interventions. Search methods We searched the Cochrane Stroke Group Trials Register (November 2012), the Cochrane Effective Practice and Organization of Care Group Trials Register (November 2012), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 11, 2012), MEDLINE (1950 to November 2012), EMBASE (1980 to November 2012) and eight additional databases. We searched trial registries, conference proceedings and reference lists. Selection criteria Randomised controlled trials (RCTs) of telerehabilitation in stroke. We included studies that compared telerehabilitation with in-person rehabilitation or no rehabilitation. In addition, we synthesised and described the results of RCTs that compared two different methods of delivering telerehabilitation services without an alternative group. We included rehabilitation programmes that used a combination of telerehabilitation and in-person rehabilitation provided that the greater proportion of intervention was provided via telerehabilitation. Data collection and analysis Two review authors independently identified trials on the basis of prespecified inclusion criteria, extracted data and assessed risk of bias. A third review author moderated any disagreements. The review authors contacted investigators to ask for missing information. Main results We included in the review 10 trials involving a total of 933 participants. The studies were generally small, and reporting quality was often inadequate, particularly in relation to blinding of outcome assessors and concealment of allocation. Selective outcome reporting was apparent in several studies. Study interventions and comparisons varied, meaning that in most cases, it was inappropriate to pool studies. Intervention approaches included upper limb training, lower limb and mobility retraining, case management and caregiver support. Most studies were conducted with people in the chronic phase following stroke. Primary outcome: no statistically significant results for independence in activities of daily living (based on two studies with 661 participants) were noted when a case management intervention was evaluated. Secondary outcomes: no statistically significant results for upper limb function (based on two studies with 46 participants) were observed when a computer programme was used to remotely retrain upper limb function. Evidence was insufficient to draw conclusions on the effects of the intervention on mobility, health-related quality of life or participant satisfaction with the intervention. No studies evaluated the cost-effectiveness of telerehabilitation. No studies reported on the occurrence of adverse events within the studies. Authors' conclusions We found insufficient evidence to reach conclusions about the effectiveness of telerehabilitation after stroke. Moreover, we were unable to find any randomised trials that included an evaluation of cost-effectiveness. Which intervention approaches are most appropriately adapted to a telerehabilitation approach remain unclear, as does the best way to utilise this approach

Correlated Hybrid Fluctuations from Inflation with Thermal Dissipation

We investigate the primordial scalar perturbations in the thermal dissipative inflation where the radiation component (thermal bath) persists and the density fluctuations are thermally originated. The perturbation generated in this model is hybrid, i.e. it consists of both adiabatic and isocurvature components. We calculate the fractional power ratio ($S$) and the correlation coefficient ($\cos\Delta$) between the adiabatic and the isocurvature perturbations at the commencing of the radiation regime. Since the adiabatic/isocurvature decomposition of hybrid perturbations generally is gauge-dependent at super-horizon scales when there is substantial energy exchange between the inflaton and the thermal bath, we carefully perform a proper decomposition of the perturbations. We find that the adiabatic and the isocurvature perturbations are correlated, even though the fluctuations of the radiation component is considered uncorrelated with that of the inflaton. We also show that both $S$ and $\cos \Delta$ depend mainly on the ratio between the dissipation coefficient $\Gamma$ and the Hubble parameter $H$ during inflation. The correlation is positive ($\cos\Delta > 0$) for strong dissipation cases where $\Gamma/H >0.2$, and is negative for weak dissipation instances where $\Gamma/H <0.2$. Moreover, $S$ and $\cos \Delta$ in this model are not independent of each other. The predicted relation between $S$ and $\cos\Delta$ is consistent with the WMAP observation. Other testable predictions are also discussed.Comment: 18 pages using revtex4, accepted for publication in PR

The Error and Repair Catastrophes: A Two-Dimensional Phase Diagram in the Quasispecies Model

This paper develops a two gene, single fitness peak model for determining the equilibrium distribution of genotypes in a unicellular population which is capable of genetic damage repair. The first gene, denoted by $\sigma_{via}$, yields a viable organism with first order growth rate constant $k > 1$ if it is equal to some target ``master'' sequence $\sigma_{via, 0}$. The second gene, denoted by $\sigma_{rep}$, yields an organism capable of genetic repair if it is equal to some target ``master'' sequence $\sigma_{rep, 0}$. This model is analytically solvable in the limit of infinite sequence length, and gives an equilibrium distribution which depends on \mu \equiv L\eps , the product of sequence length and per base pair replication error probability, and \eps_r , the probability of repair failure per base pair. The equilibrium distribution is shown to exist in one of three possible ``phases.'' In the first phase, the population is localized about the viability and repairing master sequences. As \eps_r exceeds the fraction of deleterious mutations, the population undergoes a ``repair'' catastrophe, in which the equilibrium distribution is still localized about the viability master sequence, but is spread ergodically over the sequence subspace defined by the repair gene. Below the repair catastrophe, the distribution undergoes the error catastrophe when $\mu$ exceeds \ln k/\eps_r , while above the repair catastrophe, the distribution undergoes the error catastrophe when $\mu$ exceeds $\ln k/f_{del}$, where $f_{del}$ denotes the fraction of deleterious mutations.Comment: 14 pages, 3 figures. Submitted to Physical Review

Unveiling Neutrino Mixing and Leptonic CP Violation

We review the present understanding of neutrino masses and mixings, discussing what are the unknowns in the three family oscillation scenario. Despite the anticipated success coming from the planned long baseline neutrino experiments in unraveling the leptonic mixing sector, there are two important unknowns which may remain obscure: the mixing angle $\theta_{13}$ and the CP-phase $\delta$. The measurement of these two parameters has led us to consider the combination of superbeams and neutrino factories as the key to unveil the neutrino oscillation picture.Comment: Invited brief review, 18 pages, 6 figure

Current cosmological bounds on neutrino masses and relativistic relics

We combine the most recent observations of large-scale structure (2dF and SDSS galaxy surveys) and cosmic microwave anisotropies (WMAP and ACBAR) to put constraints on flat cosmological models where the number of massive neutrinos and of massless relativistic relics are both left arbitrary. We discuss the impact of each dataset and of various priors on our bounds. For the standard case of three thermalized neutrinos, we find an upper bound on the total neutrino mass sum m_nu < 1.0 (resp. 0.6) eV (at 2sigma), using only CMB and LSS data (resp. including priors from supernovae data and the HST Key Project), a bound that is quite insensitive to the splitting of the total mass between the three species. When the total number of neutrinos or relativistic relics N_eff is left free, the upper bound on sum m_nu (at 2sigma, including all priors) ranges from 1.0 to 1.5 eV depending on the mass splitting. We provide an explanation of the parameter degeneracy that allows larger values of the masses when N_eff increases. Finally, we show that the limit on the total neutrino mass is not significantly modified in the presence of primordial gravitational waves, because current data provide a clear distinction between the corresponding effects.Comment: 13 pages, 6 figure

Study and optimization of RPCs for high rate applications

Due to the low cost, good time resolution and the properties of RPCs with respect to electronics damage protection, they are chosen for many large experiments. These detectors are reliable and stable in their operation with counting rates up to kHz/cm2. The aim of this work is to understand the fundamental rate limits of RPCs in order to find an efficient way for their optimization and hence, extend their applications. Several types of materials have been used and operational parameters have been optimized in this work comprising simulations and experiment. High efficiency, excellent position resolution, low noise and high rate capability is demonstrated. These type of RPCs open new avenues in several applications, for example in crystallography, biology and medicine