551 research outputs found
The Phenomenon of Exquisite Motor Control in Tic Disorders and its Pathophysiological Implications
The unifying characteristic of movement disorders is the phenotypic presentation of abnormal motor outputs, either as isolated phenomena or in association with further clinical, often neuropsychiatric, features. However, the possibility of a movement disorder also characterized by supranormal or enhanced volitional motor control has not received attention. Based on clinical observations and cases collected over a number of years, we here describe the intriguing clinical phenomenon that people with tic disorders are often able to control specific muscle contractions as part of their tic behaviors to a degree that most humans typically cannot. Examples are given in accompanying video documentation. We explore medical literature on this topic and draw analogies with early research of fine motor control physiology in healthy humans. By systematically analyzing the probable sources of this unusual capacity, and focusing on neuroscientific accounts of voluntary motor control, sensory feedback, and the role of motor learning in tic disorders, we provide a novel pathophysiological account explaining both the presence of exquisite control over motor output and that of overall tic behaviors. We finally comment on key questions for future research on the topic and provide concluding remarks on the complex movement disorder of tic behaviors
The Phenomenon of Exquisite Motor Control in Tic Disorders and its Pathophysiological Implications
The unifying characteristic of movement disorders is the phenotypic presentation of abnormal motor outputs, either as isolated phenomena or in association with further clinical, often neuropsychiatric, features. However, the possibility of a movement disorder also characterized by supranormal or enhanced volitional motor control has not received attention. Based on clinical observations and cases collected over a number of years, we here describe the intriguing clinical phenomenon that people with tic disorders are often able to control specific muscle contractions as part of their tic behaviors to a degree that most humans typically cannot. Examples are given in accompanying video documentation. We explore medical literature on this topic and draw analogies with early research of fine motor control physiology in healthy humans. By systematically analyzing the probable sources of this unusual capacity, and focusing on neuroscientific accounts of voluntary motor control, sensory feedback, and the role of motor learning in tic disorders, we provide a novel pathophysiological account explaining both the presence of exquisite control over motor output and that of overall tic behaviors. We finally comment on key questions for future research on the topic and provide concluding remarks on the complex movement disorder of tic behaviors
Biharmonic pattern selection
A new model to describe fractal growth is discussed which includes effects
due to long-range coupling between displacements . The model is based on the
biharmonic equation in two-dimensional isotropic defect-free
media as follows from the Kuramoto-Sivashinsky equation for pattern formation
-or, alternatively, from the theory of elasticity. As a difference with
Laplacian and Poisson growth models, in the new model the Laplacian of is
neither zero nor proportional to . Its discretization allows to reproduce a
transition from dense to multibranched growth at a point in which the growth
velocity exhibits a minimum similarly to what occurs within Poisson growth in
planar geometry. Furthermore, in circular geometry the transition point is
estimated for the simplest case from the relation
such that the trajectories become stable at the growing surfaces in a
continuous limit. Hence, within the biharmonic growth model, this transition
depends only on the system size and occurs approximately at a distance far from a central seed particle. The influence of biharmonic patterns on
the growth probability for each lattice site is also analysed.Comment: To appear in Phys. Rev. E. Copies upon request to
[email protected]
Mechanochemical endovenous Ablation versus RADiOfrequeNcy Ablation in the treatment of primary great saphenous vein incompetence (MARADONA):Study protocol for a randomized controlled trial
BACKGROUND: Radiofrequency ablation (RFA) is associated with an excellent outcome in the treatment of great saphenous vein (GSV) incompetence. The use of thermal energy as a treatment source requires the instillation of tumescence anesthesia. Mechanochemical endovenous ablation (MOCA) combines mechanical endothelial damage, using a rotating wire, with the infusion of a liquid sclerosant. Tumescence anesthesia is not required. Preliminary experiences with MOCA showed good results and low post-procedural pain. METHODS/DESIGN: The MARADONA (Mechanochemical endovenous Ablation versus RADiOfrequeNcy Ablation) trial is a multicenter randomized controlled trial in which 460 patients will be randomly allocated to MOCA or RFA. All patients with primary GSV incompetence who meet the eligibility criteria will be invited to participate in this trial. The primary endpoints are anatomic and clinical success at a one-year follow-up, and post-procedural pain. The secondary endpoints are technical success, complications, operation time, procedural pain, disease-specific quality of life, time taken to return to daily activities and/or work, and cost-efficiency analyses after RFA or MOCA. Both groups will be evaluated on an intention to treat base. DISCUSSION: The MARADONA trial is designed to show equal results in anatomic and clinical success after one year, comparing MOCA with RFA. In our hypothesis MOCA has an equal anatomic and clinical success compared with RFA, with less post-procedural pain. TRIAL REGISTRATION: Clinicaltrials NCT0193616
Effects of Limit Feeding Cold Stressed Growing Calves in the Morning Versus the Evening, as well as Bunk Line Sharing on Performance
Objective: To determine the response of cold stressed growing calves to being fed in the evening instead of morning hours, as well as the effect of bunk line sharing.
Study Description: Crossbred steers (n = 360) of Texas, Oklahoma, and Idaho origin were blocked by weight into four size groups and randomly assigned to pens, which were randomly allocated to one of five treatments. All steers received a diet formulated to provide 60 Mcal net energy for gain/100 lb of dry matter and were limit fed with a target of 2.0% of their body weight in dry matter intake. Treatments consisted of being fed in the morning (AM), in the evening (PM), fed half of their feed in the morning and half in the evening (50/50), and two treatments that allowed cattle to be fed in the same pen yet were rotated twice daily utilizing a holding pen, allowing for half of the calves to be fed in the morning (Shuttle AM) and half to be fed in the evening (Shuttle PM), doubling the use of the pen and bunk line. The steers were fed for 77 days and individual animal weights were taken on day -1 (allocation), day 0 (initial processing), day 64/65 (blood sampling), and day 77 (final weights). Plasma glucose was obtained individually on day 64 and 65, and pen weights were collected on days 0, 21, 28, 35, 56, 63, 70, and 77.
The Bottom Line: When limit feeding cold stressed growing calves, neither shifting from morning feed delivery to evening feed delivery, nor bunk line sharing significantly improves the efficiency of feed conversion
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