Optogenetic control of spinal microcircuits : insights into locomotor rhythm and pattern generation

Mammalian locomotion is a complex task in which hundreds of muscles work together in a coordinated fashion. Neural networks in the spinal cord, known as central pattern generators (CPGs), carry all the components necessary to produce the cyclical pattern of muscle activity needed for locomotion. The fact that the locomotor CPG is innate and highly localized makes it outstanding as a subject to study how a complex, but concrete behavior, is produced by a neuronal network. Two fundamental aspects of the CPG are rhythm generation, and flexor-extensor coordination. These two properties have sometimes been linked together, such as in the half-center model, in which the alternating activity between flexors and extensors are the cause of the rhythm. Other models for rhythm generation have also been postulated, consequently no consensus exists regarding the overall structure of the CPG for locomotion. Pharmacological investigations have indicated that glutamatergic neurons as essential for locomotion. To further elucidate the function of these neurons, the work presented in this thesis has made use of a set of new tools to target glutamatergic neurons, and elucidate their specific contribution to locomotion. A mouse was produced that expressed the optically gated ion channel Channelrhodopsin-2, making it possible for the first time to selectively activate a genetically specific sub-population of neurons in the spinal cord. The experiments using this mouse show that glutamatergic neuron activation is sufficient to produce locomotor-like activity, both in the spinal cord, and in the hindbrain. With the use of another set of recently produced transgenic mice, it was possible to probe deeper into the structure of the CPG, and illuminate several key aspects of the organization of the network. Several proposed network models could be refuted and one in particular was promoted. The results show that the CPG network is build up from intrinsically rhythmic modules. Furthermore, a mouse without glutamatergic neurotransmission was examined. What was found was that the locomotion deficient mouse could produce locomotor-like activity under special conditions, and this activity depended solely on inhibitory interneurons, specifically, reciprocally connected Ia interneurons. Overall, glutamatergic neurons are shown to form intrinsically rhythmic modules that are indispensable for rhythm generation, and network function. The use of genetics and electrophysiology is a powerful combination that will continue to provide conclusions about how neural networks produce and control complex motor behavior

Games the Government Plays: Federal Funding of Minority Economic Development

The objective of this study was to investigate regional differences in injury incidence in men's professional football in Europe. A nine-season prospective cohort study was carried out between 2001–2002 and 2009–2010 involving 1357 players in 25 teams from nine countries. Teams were categorized into different regions according to the Köppen–Geiger climate classification system. Teams from the northern parts of Europe (n = 20) had higher incidences of injury overall [rate ratio 1.12, 95% confidence interval (CI) 1.06 to 1.20], training injury (rate ratio 1.16, 95% CI 1.05 to 1.27), and severe injury (rate ratio 1.29, 95% CI 1.10 to 1.52), all statistically significant, compared to teams from more southern parts (n  = 5). In contrast, the anterior cruciate ligament injury incidence was lower in the northern European teams with a statistically significant difference (rate ratio 0.43, 95% CI 0.25 to 0.77), especially for noncontact anterior cruciate ligament injury (rate ratio 0.19, 95% CI 0.09 to 0.39). In conclusion, this study suggests that there are regional differences in injury incidence of European professional football. However, further studies are needed to identify the underlying causes.Funding Agencies|UEFA Football Development Division||Swedish National Centre for Research in Sports||</p

Low-order feedforward controllers: Optimal performance and practical considerations

Feedforward control from measurable disturbances can significantly improve the performance in control loops. However, tuning rules for such controllers are scarce. In this paper design rules for how to choose optimal low-order feedforward controller parameter are presented. The parameters are chosen so that the integrated squared error, when the system is subject to a step disturbance, is minimized. The approach utilizes a controller structure that decouples the feedforward and the feedback controller. The optimal controller can suffer from undesirable high-frequency noise characteristics and tuning methods for how to filter the control signal are also provided. For scenarios where perfect disturbance attenuation in theory is achievable but where noise-filtering is needed, the concept of precompensation is introduced as a way to shift the controller time-delay to compensate for the low-pass filtering

Design of Optimal Low-Order Feedforward Controllers

Design rules for optimal feedforward controllers with lead-lag structure in the presence of measurable disturbances are presented. The design rules are based on stable first-order models with time delays, FOTD, and are optimal in the sense of minimizing the integrated-squared error. The rules are derived for an open-loop setting, considering a step disturbance. This paper also discusses a general feedforward structure, which enables decoupling in the design of feedback and feedforward controllers, and justifies the open-loop setting

Preventing knee injuries in adolescent female football players – design of a cluster randomized controlled trial [NCT00894595]

<p>Abstract</p> <p>Background</p> <p>Knee injuries in football are common regardless of age, gender or playing level, but adolescent females seem to have the highest risk. The consequences after severe knee injury, for example anterior cruciate ligament (ACL) injury, are well-known, but less is known about knee injury prevention. We have designed a cluster randomized controlled trial (RCT) to evaluate the effect of a warm-up program aimed at preventing acute knee injury in adolescent female football.</p> <p>Methods</p> <p>In this cluster randomized trial 516 teams (309 clusters) in eight regional football districts in Sweden with female players aged 13–17 years were randomized into an intervention group (260 teams) or a control group (256 teams). The teams in the intervention group were instructed to do a structured warm-up program at two training sessions per week throughout the 2009 competitive season (April to October) and those in the control group were informed to train and play as usual. Sixty-eight sports physical therapists are assigned to the clubs to assist both groups in data collection and to examine the players' acute knee injuries during the study period. Three different forms are used in the trial: (1) baseline player data form collected at the start of the trial, (2) computer-based registration form collected every month, on which one of the coaches/team leaders documents individual player exposure, and (3) injury report form on which the study therapists report acute knee injuries resulting in time loss from training or match play. The primary outcome is the incidence of ACL injury and the secondary outcomes are the incidence of any acute knee injury (except contusion) and incidence of severe knee injury (defined as injury resulting in absence of more than 4 weeks). Outcome measures are assessed after the end of the 2009 season.</p> <p>Discussion</p> <p>Prevention of knee injury is beneficial for players, clubs, insurance companies, and society. If the warm-up program is proven to be effective in reducing the incidence of knee injury, it can have a major impact by reducing the future knee injury burden in female football as well as the negative long-term disabilities associated with knee injury.</p> <p>Trial registration</p> <p>NCT00894595</p

East-West Trade Regulation in the United States (1974 Trade Act, Title IV)

The Orchard Sports Injury Classification System (OSICS) is one of the world’s most commonly used systems for coding injury diagnoses in sports injury surveillance systems. Its major strengths are that it has wide usage, has codes specific to sports medicine and that it is free to use. Literature searches and stakeholder consultations were made to assess the uptake of OSICS and to develop new versions. OSICS was commonly used in the sports of football (soccer), Australian football, rugby union, cricket and tennis. It is referenced in international papers in three sports and used in four commercially available computerised injury management systems. Suggested injury categories for the major sports are presented. New versions OSICS 9 (three digit codes) and OSICS 10.1 (four digit codes) are presented. OSICS is a potentially helpful component of a comprehensive sports injury surveillance system, but many other components are required. Choices made in developing these components should ideally be agreed upon by groups of researchers in consensus statements

Sled časa in smrt življenja: Bergson, Heidegger, Derrida

This essay develops Derrida’s logic of the trace in relation to the philosophical problem of time and the revival of “life” as a central category in contemporary thinking. Through a critical interrogation of Bergson’s and Heidegger’s conceptions of temporality, I show how the logic of the trace articulates an originary co-implication of the organic and the inorganic, the event and the machine. Refuting any vitalist conception of life, as well as any conception of an inherent dynamism of life, the deconstructive logic of the trace allows one to reckon with the philosophical implications of Darwinism.Pričujoči tekst razvija Derridajevo logiko sledi v odnosu do filozofskega problema časa in obuditve koncepta »življenja« kot osrednje kategorije sodobnega mišljenja. S kritičnim branjem Bergsonovega in Heideggerjevega pojmovanja časovnosti pokažem, kako logika sledi artikulira izvorno sovisnost organskega in anorganskega, dogodka in stroja. Dekonstrukcijska logika sledi nam omogoča, da se z zavrnitvijo slehernega vitalističnega pojmovanja življenja, kot tudi sleherne koncepcije inherentnega dinamizma življenja, soočimo s filozofskimi implikacijami darvinizma

Николай Иванович Хвисюк : к 80-летию со дня рождения

Background: No study has investigated whether newcomers to professional soccer have a different injury rate than established players.                      Purpose: The primary objective was to investigate whether being a newcomer to professional soccer influences injury rates. The secondary objective was to evaluate whether playing position and player age influence injury rates.                      Study Design: Cohort study; Level of evidence, 2.                      Methods: Twenty-six soccer clubs, with 1401 players, were followed prospectively over 9 consecutive seasons between 2001 and 2010. Club medical staff recorded time-loss injuries and soccer exposure on an individual level. Cox regression analyses were used to evaluate associations between time-loss injuries and time in professional soccer, playing position, and age.                      Results: In total, 6140 injuries and 797,389 hours of exposure were registered. A decreased general injury rate was observed for newcomers (n = 116) compared with established players (n = 3091) (hazard ratio [HR], 0.77; 95% confidence interval [CI], 0.61-0.99). In contrast, newcomers had a higher rate of fractures (rate ratio [RR], 1.77; 95% CI, 1.05-2.97), especially stress-related bone injuries (RR, 2.68; 95% CI, 1.08-6.69). Using goalkeepers as a reference, all outfield playing positions had significantly higher adjusted injury rates: defenders with an HR of 1.91 (95% CI, 1.64-2.24), midfielders with an HR of 1.78 (95% CI, 1.53-2.07), and forwards with an HR of 1.82 (95% CI, 1.55-2.14). Using players aged ≤21 years as a reference, the overall adjusted injury rate increased with age, with a peak injury rate among players aged 29 to 30 years (HR, 1.44; 95% CI, 1.24-1.68).                      Conclusion: Newcomers to professional soccer had a lower general injury rate than established players but a higher rate of stress-related bone injuries. Being a goalkeeper was associated with lower injury rates than all outfield playing positions. Injury rates increased with age, a pattern that persisted after adjusting for playing position and match exposure