Mechanisms of Impaired Motor Unit Firing Behavior in the Vastus Lateralis Muscle after Stroke

The purpose of this dissertation research project was to examine the role of impaired motor unit firing behavior on force generation after a stroke. We studied the relationship between intrinsic motoneuron properties and inhibitory sensory pathways to deficient motoneuron activity in the vastus lateralis muscle after a stroke. Individuals with stroke often have deficits with force generation and volitional relaxation. Current models of impaired force output after a stroke focus primarily on the pathology within the corticospinal pathway because of decreased descending drive. Though this is an important aspect of deficient motoneuron output, it is incomplete because motoneurons receive other inputs that can shape motor output. Because the motoneuron is the last site of signal integration for muscle contractions, using methods that study motor unit activity can provide a window to the activity in the spinal circuitry. This research study utilized a novel algorithm that decomposed electromyography (EMG) signals into the contributions of the individual motor units. This provided the individual firing instances for a large number of concurrently active motor units during isometric contractions of the knee extensors. In the first aim, the association between the hyperemic response and motor unit firing rate modulation to intermittent, fatiguing contractions was investigated. It was found that the magnitude of blood flow was lower for individuals with stroke compared to healthy controls, but both groups increased blood flow similarly in response to fatiguing contractions. This did not relate to changes in muscle fiber contractibility for the participants with stroke; rather, participants better able to increase blood flow showed greater modulation in motor unit firing rates. To further investigate how ischemic conditions impact motor unit output, the second aim used a blood pressure cuff to completely occlude blood flow through the femoral artery with the intent of activating inhibitory afferent pathways. We found that ischemic conditions had a greater inhibitory impact on motor unit output for individuals with stroke compared to healthy controls, possibly because of hyper-excitable group III/IV afferent pathways. The final aim investigated how stroke related changes in the intrinsic excitability of the motoneurons impacted prolonged motor unit firing during voluntary relaxation. A serotonin reuptake inhibitor was administered to quantify motoneuron sensitivity to neuromodulatory inputs. This study found that the serotonin reuptake inhibitor increased muscle relaxation and may have reduced persistent inward current contributions to prolonged motor unit firing. In conclusion, while damage to the corticospinal tract is a major component to poor functionality, the intrinsic properties of the motoneuron and sensory pathways to the motoneuron pool are essential for understanding deficient motor control after a stroke

On the public discourse of religion : an analysis of Christianity in the United Kingdom

Debates over the involvement of religion in the public sphere look set to be one of the defining themes of the 21st century. But while religious issues have attracted a large degree of scholarly attention, the public discourse of religion itself, in terms of the effort to assert and legitimize a role for faith in the public realm, has remained notably under-researched. This article marks an initial step to address this deficiency by deconstructing the public discourse of Christianity in the United Kingdom. It argues that, while appealing for representation on the grounds of liberal equality, the overall goal of this discourse is to establish a role for itself as a principal source of moral authority, and to exempt itself from the evidentially-based standards and criteria that govern public life

Stating the obvious: evaluating the state of public assurance in fire and rescue authorities in England

Purpose: To examine the form, content and reporting arrangements of 'statements of assurance' required from Fire and Rescue Authorities in England since their introduction in 2012 and identify potential improvements for future implementation. Design/methodology/approach: A multi-method approach was adopted which commenced with an analysis of the current official guidance, an exploration of the accessibility and structure of the current statements produced followed by a review of those statements through a desk based analysis complemented by a series of elite interviews. Findings: The current guidance was found to be too broad and open to interpretation to be fit for purpose. This has led to some significant inconsistencies in reporting, limiting the statements' usefulness to key users and stakeholders. Most authorities provided some form of report on their website but variations in respect of length, structure, name and content, limit their value. The research found that 30% of authorities did not have an up to date statement available online. These findings were supported by the series of interviews. The result has led to confusion amongst authorities as to the statement's role and the risk of it being perceived as a 'box ticking' exercise rather than a real contribution to public assurance. Practical implications: This paper provides potential lessons which could be adopted to inform future guidance in respect of the preparation and publication of the statement of assurance and its role in the wider public assurance regime for fire and rescue authorities. If adopted, these would improve the accountability, transparency and public assurance of Fire and Rescue Authorities which is a key objective of their governance arrangements. Originality/value: The statement of assurance has only been a requirement of Authorities since the current National Framework for Fire and Rescue was published in July 2012 and has not been subject to independent research since its inception. The government have recently issued a consultation on a new national framework, but this proposes no changes to the statements of assurance. The findings will therefore be of value to the government, the Fire and Rescue Sector and the recently appointed regulators for the service Her Majesty's Inspectorate of Constabulary and Fire and Rescue Services (HMICFRS)

Detection of Baryonic Acoustic Oscillations in the Matter Power Spectrum

Using the spectra of 22,923 high-redshift quasars from the Baryon Oscillation Spectrosocpic Survey (BOSS) subset of the Sloan Digital Sky Survey (SDSS), the authors detect evidence of the primordial baryonic acoustic oscillations (BAOs) in the matter power spectrum. The detection further endorses the currently accepted Lambda-CDM model of cosmology based upon the existence of dark energy (Lambda) and cold dark matter (CDM). Additionally, the use of the continuous wavelet transform to calculate the power spectrum has many advantages over traditional Fourier methods and independently corroborates previous detections

An EPR investigation of binding environments by N-donor chelating exchange resins for Cu extraction from aqueous media

EPR and UV−vis spectroscopy were collectively used to characterize a series of Cu(II) binding environments within two chelating exchange resins, Dowex and CuWRAM, used for Cu(II) extraction from aqueous media. A series of well-defined intra- and intermolecular binding sites have been identified as responsible for Cu(II) uptake

Impaired Hyperemic Response to Exercise Post Stroke

Individuals with chronic stroke have reduced perfusion of the paretic lower limb at rest; however, the hyperemic response to graded muscle contractions in this patient population has not been examined. This study quantified blood flow to the paretic and non-paretic lower limbs of subjects with chronic stroke after submaximal contractions of the knee extensor muscles and correlated those measures with limb function and activity. Ten subjects with chronic stroke and ten controls had blood flow through the superficial femoral artery quantified with ultrasonography before and immediately after 10 second contractions of the knee extensor muscles at 20, 40, 60, and 80% of the maximal voluntary contraction (MVC) of the test limb. Blood flow to the paretic and non-paretic limb of stroke subjects was significantly reduced at all load levels compared to control subjects even after normalization to lean muscle mass. Of variables measured, increased blood flow after an 80% MVC was the single best predictor of paretic limb strength, the symmetry of strength between the paretic and non-paretic limbs, coordination of the paretic limb, and physical activity. The impaired hemodynamic response to high intensity contractions was a better predictor of lower limb function than resting perfusion measures. Stroke-dependent weakness and atrophy of the paretic limb do not explain the reduced hyperemic response to muscle contraction alone as the response is similarly reduced in the non-paretic limb when compared to controls. These data may suggest a role for perfusion therapies to optimize rehabilitation post stroke