Identifying candidates for targeted gait rehabilitation: better prediction through biomechanics-informed characterization

BACKGROUND: Walking speed has been used to predict the efficacy of gait training; however, poststroke motor impairments are heterogeneous and different biomechanical strategies may underlie the same walking speed. Identifying which individuals will respond best to a particular gait rehabilitation program using walking speed alone may thus be limited. The objective of this study was to determine if, beyond walking speed, participants' baseline ability to generate propulsive force from their paretic limbs (paretic propulsion) influences the improvements in walking speed resulting from a paretic propulsion-targeting gait intervention. METHODS: Twenty seven participants >6 months poststroke underwent a 12-week locomotor training program designed to target deficits in paretic propulsion through the combination of fast walking with functional electrical stimulation to the paretic ankle musculature (FastFES). The relationship between participants' baseline usual walking speed (UWSbaseline), maximum walking speed (MWSbaseline), and paretic propulsion (propbaseline) versus improvements in usual walking speed (∆UWS) and maximum walking speed (∆MWS) were evaluated in moderated regression models. RESULTS: UWSbaseline and MWSbaseline were, respectively, poor predictors of ΔUWS (R 2  = 0.24) and ΔMWS (R 2  = 0.01). Paretic propulsion × walking speed interactions (UWSbaseline × propbaseline and MWSbaseline × propbaseline) were observed in each regression model (R 2 s = 0.61 and 0.49 for ∆UWS and ∆MWS, respectively), revealing that slower individuals with higher utilization of the paretic limb for forward propulsion responded best to FastFES training and were the most likely to achieve clinically important differences. CONCLUSIONS: Characterizing participants based on both their walking speed and ability to generate paretic propulsion is a markedly better approach to predicting walking recovery following targeted gait rehabilitation than using walking speed alone

Better drug therapy for the children of Africa: current impediments to success and potential strategies for improvement

A commentary is presented on the urgent need for a comprehensive effort to improve the practice of pediatric therapeutics in Africa. A call for action is addressed to a variety of practitioners internationally, many of whom possess skills that could be fruitfully applied to the improvement of health outcomes for African children. Successful engagement with the many challenges requires the complementary effort of researchers in basic and clinical pharmacology and toxicology, nurses, pharmacists, physicians, clinical pharmacologists, clinical pharmacists, and political leaders and civil servants. While a comprehensive or systematic review of the relevant literature has not been attempted, the authors have highlighted promising initiatives driven by international agencies and academic networks. Two African perspectives are presented to reinforce the prospect of child health gains that can be achieved through consistent pursuit of optimal therapy for conditions such as respiratory infection, diarrhea, malaria, and HIV/AIDS. There is an imperative for development of north-south and south-south partnerships that will amplify current research efforts and mobilize existing knowledge concerning pediatric drugs. The overall goal is a multidisciplinary commitment to making essential medicines available at the right time, the right place, and in the right formulation for African children from infancy to adolescence

Merger of white dwarf-neutron star binaries: Prelude to hydrodynamic simulations in general relativity

White dwarf-neutron star binaries generate detectable gravitational radiation. We construct Newtonian equilibrium models of corotational white dwarf-neutron star (WDNS) binaries in circular orbit and find that these models terminate at the Roche limit. At this point the binary will undergo either stable mass transfer (SMT) and evolve on a secular time scale, or unstable mass transfer (UMT), which results in the tidal disruption of the WD. The path a given binary will follow depends primarily on its mass ratio. We analyze the fate of known WDNS binaries and use population synthesis results to estimate the number of LISA-resolved galactic binaries that will undergo either SMT or UMT. We model the quasistationary SMT epoch by solving a set of simple ordinary differential equations and compute the corresponding gravitational waveforms. Finally, we discuss in general terms the possible fate of binaries that undergo UMT and construct approximate Newtonian equilibrium configurations of merged WDNS remnants. We use these configurations to assess plausible outcomes of our future, fully relativistic simulations of these systems. If sufficient WD debris lands on the NS, the remnant may collapse, whereby the gravitational waves from the inspiral, merger, and collapse phases will sweep from LISA through LIGO frequency bands. If the debris forms a disk about the NS, it may fragment and form planets.Comment: 28 pages, 25 figures, 6 table

Characterizing the Optical Variability of Bright Blazars: Variability-based Selection of Fermi Active Galactic Nuclei

We investigate the use of optical photometric variability to select and identify blazars in large-scale time-domain surveys, in part to aid in the identification of blazar counterparts to the ∼30% of γ -ray sources in the Fermi 2FGL catalog still lacking reliable associations. Using data from the optical LINEAR asteroid survey, we characterize the optical variability of blazars by fitting a damped random walk model to individual light curves with two main model parameters, the characteristic timescales of variability τ , and driving amplitudes on short timescales σ . Imposing cuts on minimum τ and σ allows for blazar selection with high efficiency E and completeness C. To test the efficacy of this approach, we apply this method to optically variable LINEAR objects that fall within the several arcminute error ellipses of γ -ray sources in the Fermi 2FGL catalog. Despite the extreme stellar contamination at the shallow depth of the LINEAR survey, we are able to recover previously associated optical counterparts to Fermi active galactic nuclei with E ≥ 88% and C = 88% in Fermi 95% confidence error ellipses having semimajor axis r < 8'. We find that the suggested radio counterpart to Fermi source 2FGL J1649.6+5238 has optical variability consistent with other γ -ray blazars and is likely to be the γ -ray source. Our results suggest that the variability of the non-thermal jet emission in blazars is stochastic in nature, with unique variability properties due to the effects of relativistic beaming. After correcting for beaming, we estimate that the characteristic timescale of blazar variability is ∼3 years in the rest frame of the jet, in contrast with the ∼320 day disk flux timescale observed in quasars. The variability-based selection method presented will be useful for blazar identification in time-domain optical surveys and is also a probe of jet physics

The United Kingdom, Republic of Ireland, United States and the conflict in Northern Ireland, August 1971 - September 1974

This thesis offers a new interpretation of the international history of the early period of Northern Ireland’s ‘Troubles’. Such a revision is necessary given the recently released material in the national archives of the United Kingdom, Republic of Ireland and the United States, and in the personal archives of those involved. Furthermore, by adopting a different methodology, made possible by the recent archive material, further new perspectives emerge of the international dimension. Rather than taking a single element of the international history of the Troubles – for example, the ‘Irish dimension’, ‘American dimension’, the Cold War, or European integration – this thesis takes a multidimensional approach analysing the impact of the interactions of each of the international actors. The starting point for this multidimensional analysis is the introduction of internment without trial on 9 August 1971. This was not just a significant event in Northern Ireland, but also had the effect of internationalising the Troubles. Over the months that followed the international dimension developed two distinct spheres of activity – a political sphere and a security sphere. Different combinations of actors interacted in each of these spheres. In addition to the moderate Northern Irish parties, the British and Irish governments participated in the political sphere. The US government eventually ruled itself out of this sphere following the US presidential election in November 1972, but only after it had flirted with intervention. However, interventions by the US Congress’s ‘Irish Caucus’ continued. Meanwhile, in the security sphere, comprehensive Anglo-Irish security cooperation proved impossible to achieve. Instead, Anglo-American and Hiberno-American security cooperation developed – with Dublin eventually exerting as much of an influence on US policy as the UK. However, the US government’s attempts to supress IRA support were seriously restricted by the administration’s unwillingness to pick a fight with the Irish Caucus. The international dimension was an integral component of the peace process that resulted in the establishing of a cross-community power-sharing executive and the Sunningdale Agreement of December 1973. Even when this process was brought to an end by a Protestant backlash in May 1974 the principles developed during this period were confirmed and were to be central to future peace initiatives in Northern Ireland, including the Good Friday Agreement

Chromatic Illumination Discrimination Ability Reveals that Human Colour Constancy Is Optimised for Blue Daylight Illuminations

The phenomenon of colour constancy in human visual perception keeps surface colours constant, despite changes in their reflected light due to changing illumination. Although colour constancy has evolved under a constrained subset of illuminations, it is unknown whether its underlying mechanisms, thought to involve multiple components from retina to cortex, are optimised for particular environmental variations. Here we demonstrate a new method for investigating colour constancy using illumination matching in real scenes which, unlike previous methods using surface matching and simulated scenes, allows testing of multiple, real illuminations. We use real scenes consisting of solid familiar or unfamiliar objects against uniform or variegated backgrounds and compare discrimination performance for typical illuminations from the daylight chromaticity locus (approximately blue-yellow) and atypical spectra from an orthogonal locus (approximately red-green, at correlated colour temperature 6700 K), all produced in real time by a 10-channel LED illuminator. We find that discrimination of illumination changes is poorer along the daylight locus than the atypical locus, and is poorest particularly for bluer illumination changes, demonstrating conversely that surface colour constancy is best for blue daylight illuminations. Illumination discrimination is also enhanced, and therefore colour constancy diminished, for uniform backgrounds, irrespective of the object type. These results are not explained by statistical properties of the scene signal changes at the retinal level. We conclude that high-level mechanisms of colour constancy are biased for the blue daylight illuminations and variegated backgrounds to which the human visual system has typically been exposed

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy