Publications by authors named "Hogan N"

Our objective in this study was to assess passive mechanical stiffness in the ankle of chronic hemiparetic stroke survivors and to compare it with those of healthy young and older (age-matched) individuals. Given the importance of the ankle during locomotion, an accurate estimate of passive ankle stiffness would be valuable for locomotor rehabilitation, potentially providing a measure of recovery and a quantitative basis to design treatment protocols. Using a novel ankle robot, we characterized passive ankle stiffness both in sagittal and in frontal planes by applying perturbations to the ankle joint over the entire range of motion with subjects in a relaxed state.

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Motor neuroscience is well over 100 years old, with seminal work such as G. T. Fritz and E.

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Understanding the dynamics of wrist rotations is important for many fields, including biomechanics, rehabilitation and motor neuroscience. This paper provides an experimentally based mathematical model of wrist rotation dynamics in Flexion-Extension (FE) and Radial-Ulnar Deviation (RUD), and characterizes the torques required to overcome the passive mechanical impedance of wrist rotations. We modeled the wrist as a universal joint with non-intersecting axes.

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Dynamically entraining human gait with periodic torque from a robot may provide an approach to walking therapy that is uniquely supportive of normal biological function. To test the feasibility of this approach we perturbed the gait of unimpaired human subjects by applying a periodic impulsive ankle torque at various frequencies. Eighteen subjects out of 19 exhibited entrained gaits: for a small range of frequencies their gait periods adapted to synchronize with the mechanical perturbation.

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The objective of this study was to examine the immune toxicity of the alkyl polycyclic aromatic hydrocarbon (PAH) retene (7-isopropyl-1-methyl phenanthrene) in rainbow trout. Retene is a common alkyl PAH associated with combustion of terrestrial plants or industrial effluents. Rainbow trout were injected intraperitoneally with a single dose of 0, 1, or 10mg/kg of retene and sampled at 21d.

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Background: There are many procedures described for the correction of severe hallux valgus. This is the first to examine the role of a basal osteotomy with distal soft tissue release.

Methods: 26 patients with severe hallux valgus underwent a basal chevron osteotomy with distal soft tissue release.

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Through in-depth interviews, this study explored perceptions and experiences of key players handling child sexual offense cases in Dar es Salaam, Tanzania. The informants included public police investigators, magistrates, legal workers, and social workers working with nongovernmental organizations. The interviews were recorded, transcribed verbatim, and analyzed using qualitative content analysis.

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Analysis of motor performance variability in tasks with redundancy affords insight about synergies underlying central nervous system (CNS) control. Preferential distribution of variability in ways that minimally affect task performance suggests sophisticated neural control. Unfortunately, in the analysis of variability the choice of coordinates used to represent multi-dimensional data may profoundly affect analysis, introducing an arbitrariness which compromises its conclusions.

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Work-family conflict and job burnout are both issues for 272 correctional staff (response rate of 68%). The two major forms of work-family conflict are work-on-family conflict and family-on-work conflict. Multivariate analysis of survey data from 272 correctional staff at a state prison indicated work-on-family conflict had a significant positive relation with job burnout, while family-on-work conflict did not.

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The control of wrist rotations is critical for normal upper limb function, yet has received little attention. In this study, we characterized path shape of wrist rotations in order to better understand the biomechanical and neural factors governing their control. Subjects performed step-tracking wrist rotations in eight directions "at a comfortable speed" and "as fast as possible.

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Previous studies have shown that mummichog (Fundulus heteroclitus; a lunar, asynchronous-spawning killifish of the western Atlantic) exposed to 17alpha-ethynylestradiol (EE2) exhibit decreased plasma reproductive steroid levels, decreased gonadal steroid production, increased plasma vitellogenin, decreased fecundity and impaired fertilization. The objective of this study was to determine the potential mechanisms by which EE2 depresses gonadal steroidogenesis and influences estrogen signalling in the mummichog. Adult recrudesced fish were exposed to the potent synthetic estrogen, ethinylestradiol (EE2; 0-270ng/L) for 14 days.

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We tested 23 healthy participants who performed rhythmic horizontal movements of the elbow. The required amplitude and frequency ranges of the movements were specified to the participants using a closed shape on a phase-plane display, showing angular velocity versus angular position, such that participants had to continuously control both the speed and the displacement of their forearm. We found that the combined accuracy in velocity and position throughout the movement was not a monotonic function of movement speed.

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Background And Research Objectives: : Multiple sociodemographic and environmental factors have been associated with urgent treatment-seeking behaviors for patients experiencing acute coronary syndromes (ACSs). However, variables that directly affect the decision to seek care in the emergency department (ED) have been less well defined. The objective of this study was to explore the factors associated with a decision to seek care for symptoms of ACSs and to describe patient characteristics associated with time to presentation.

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Studies of sensory-motor performance, including those concerned with changes because of age, disease, or therapeutic intervention, often use measures based on jerk, the time derivative of acceleration, to quantify smoothness and coordination. However, results have been mixed: some researchers report sensitive discrimination of subtle differences, whereas others fail to find significant differences even when they are obviously present. One reason for this is that different measures have been used with different scaling factors.

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Social reactions to rape are socioculturally determined and have a strong influence on the coping and recovery of the survivor. The existing knowledge on social reactions emanates from Western countries with limited research attention on non-Western populations, particularly sub-Saharan Africa. We aimed to establish the types and perceptions of social reactions that are expressed to rape survivors and people's intentions to express them to survivors of varied social backgrounds in Tanzania.

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Background: Injuries to the cervical spine (C-spine) are among the most serious in rugby and are well documented. Front-row players are particularly at risk due to repetitive high-intensity collisions in the scrum.

Aim: This study evaluates degenerative changes of the C-spine and associated symptomatology in front-row rugby players.

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According to the existing literature, support for punishment and support for treatment of inmates are the two major orientations held by correctional workers. There is a small but growing body of studies that has examined the predictors of these orientations. The literature suggests that personal characteristics account for little of the variance in correctional orientations whereas individual-level perceptions of work environment factors are related to correctional orientations; however, the effects of job burnout have not been explored.

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The understanding that recovery of brain function after stroke is imperfect has prompted decades of effort to engender speedier and better recovery through environmental manipulation. Clinical evidence has shown that the performance plateau exhibited by patients with chronic stroke, usually signaling an end of standard rehabilitation, might represent a period of consolidation rather than a performance optimum. These results highlight the difficulty of translating pertinent neurological data into pragmatic changes in clinical programs.

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Background: People with Multiple Sclerosis have a life long need for physiotherapy and exercise interventions due to the progressive nature of the disease and their greater risk of the complications of inactivity. The Multiple Sclerosis Society of Ireland run physiotherapy, yoga and exercise classes for their members, however there is little evidence to suggest which form of physical activity optimises outcome for people with the many and varied impairments associated with MS.

Methods And Design: This is a multi-centre, single blind, block randomised, controlled trial.

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The presence of unidentified estrogens and androgens in effluents from pulp and paper mills is well documented. However, their role in effluent effects on fish reproduction remains unclear. The objective of this study was to investigate the hypothesis that reproductive impacts of a modern pulp mill effluent are mediated by androgens and/or estrogens in the effluent.

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We reviewed some of our initial insights about the process of upper-limb behavioral recovery following stroke. Evidence to date indicates that intensity, task specificity, active engagement, and focusing training on motor coordination are key factors enabling efficacious recovery. On modeling, experience with over 400 stroke patients has suggested a working model of recovery similar to implicit motor learning.

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To interact mechanically with the world and especially to use hand tools we exert force. However, the biomechanical consequences of force production can be challenging. In particular, due to the nonlinear kinematics of the mammalian skeleton and of typical hand tools, exerting force can destabilize posture, compromising the ability to control force.

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Cluster analysis was performed on a diverse group of 69 non-clinical grievers whose loved ones died between 12-40 months prior to the study. Based on psychometric measures of both bereavement distress and growth, three distinct clusters emerged: High Grief (high distress-low growth; n = 16); High Growth (low distress-high growth; n = 32); and Low Impact (low distress-low growth; n = 21). Discriminant function analyses showed that the High Grief cluster differed robustly from the other two groups on several measures of grief adaptation and coping; the differences between the High Growth and Low Impact clusters were less pronounced.

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A method to evaluate the expression of three hormone responsive genes, vitellogenin (estrogens), spiggin (androgens), and an androgen receptor (ARbeta) using real-time PCR in threespine stickleback is presented. Primers were designed from previously characterised spiggin and ARbeta sequences, while a homology cloning strategy was used to isolate a partial gene sequence for stickleback vitellogenin (Vtg). Spiggin mRNA was significantly higher in kidneys of field-caught males compared to females by greater than five orders of magnitude while ARbeta levels were only 1.

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