A mathematical model of wheelchair racing

Wheelchair racing strokes are very complicated movements, which involve a coupling between the athlete and his or her racing chair. Each body segment, as well as the wheel, follows a distinct trajectory as the motion is performed. Understanding the kinematics and kinetics of various stroke techniques would provide the athletes and their coaches with information, which could help guide the racers toward improved performances. In this thesis, a mathematical model is developed, which is capable of providing such valuable kinematic and kinetic information. This two-dimensional model represents the body segments as a coupled pendulum system of point masses and the wheel as a distributed-mass disk. Furthermore, the model incorporates several fundamental assumptions, including that the stroke cycle can be divided into an arbitrary number of consecutive ballistic phases such that segment positions are continuous at phase boundaries. Each phase is mathematically a second-order, nonlinear ordinary boundary value problem (BVP). Numerical methods are used to solve the BVPs independently, resulting in velocity discontinuities at the phase boundaries. These instantaneous velocity increases or decreases must be caused by impulsive forces. In turn, these impulsive forces are interpreted as muscular input and/or physical impacts. In this research, the model is used to produce numerous stroke techniques, which are consistent with a given racer\u27s structural parameters and prescribed stroke characteristics (racing speed, cycle time, recovery cycle time, the athlete\u27s orientation in the racing chair, and wheel contact and release angles). The kinematics of these different techniques are contrasted. In addition, the muscular mechanical energy costs of these strokes are determined and an interpretation as to the mechanical energy efficiency of each technique is given. The model is used to provide insight into the intricacies of an actual wheelchair racing stroke. In this thesis, the kinematics and energetics of model-produced techniques guide the analysis of these characteristics of an empirical stroke. One conclusion of this analysis is that this model may be able to provide more mechanically efficient alternative strokes from which the athlete can choose. Finally, suggestions are offered toward improving the model

burning Dinner Is Not Incompetence But War : Marriage And Madness In Contemporary Domestic Fiction

This thesis explores the prevalent theme of marriage and madness in sixteen domestic novels published between 1958 and 1985 by writers such as Anderson, Atwood, Ballantyne, Engel, Kaufman, Laurence, Lessing, Mortimer and Plath. The representation of the restrictiveness of traditional domestic roles figures centrally in the work of many women writers during this period; almost as common is the conjunction between this sense of restriction and the need to escape these ties that bind. Departure and divorce present themselves as possibilities, but for women who are economically and emotionally dependent on the traditional structure of marriage in Western society, various forms of mental illness more often constitute the only means of escape. The prevalence of this connection between marriage and madness in contemporary women\u27s fiction has led to the recent recognition of the mad housewife novel as a unique literary genre.;The very concept of madness itself, which has been extensively explored in the recent work of feminist theorists and cultural historians, is interrogated in significant ways in this literature. By moving beyond a dualistic medical model of sickness and health, contemporary women writers are able to view madness as a label imposed to control and categorize those who deviate from cultural norms. In the case of the protagonists of the mad housewife novel, this deviation can be seen as a refusal to accept the inequality of gendered roles in traditional marriage, a refusal which finds expression in depression or rage.;Restricted and silenced by patriarchal cultural institutions, the protagonists of these novels ultimately attempt to escape the marital and medical ties that confine them within traditional female roles and stereotypes. Their outward escapes from husbands and male psychiatrists most often take the form of physical journeys or extra-marital relationships, while inward escapes range from drug and alcohol abuse to dreams, journals, and self-expression through art. In the end, however, the temporary nature of these escapes constitutes a compelling comment on the enormous power of the cultural pressures that keep women in their place within the institutions of marriage and madness

Effect of kappa-opioid receptor agonists U69593, U50488H, spiradoline and salvinorin A on cocaine-induced drug-seeking in rats

Our previous work indicated that pretreatment with the selective kappa opioid receptor (KOPr) agonist, U69593, attenuated the ability of priming injections of cocaine to reinstate extinguished cocaine-seeking behavior. The present study expanded these initial tests to include other traditional KOPr agonists, U50488H, spiradoline (SPR), and salvinorin A (Sal A), an active constituent of the plant Salvia divinorum. Following acquisition and stabilization of cocaine self-administration, cocaine-produced drug-seeking was measured. This test was conducted in a single day and comprised an initial phase of self-administration, followed by a phase of extinguished responding. The final phase examined reinstatement of extinguished cocaine self-administration followed by a priming injection of cocaine (20.0 mg/kg, intraperitoneal (I.P.)) in combination with the various KOPr agonists. Cocaine-induced drug-seeking was attenuated by pretreatment with U69593 (0.3 mg/kg, subcutaneous (S.C.)), U50488H (30.0 mg/kg, I.P.), SPR (1.0, 3.0 mg/kg, I.P.) and Sal A (0.3, 1.0 mg/kg, I.P.). Sal A (0.3, 1.0 mg/kg, I.P.) had no effect on operant responding to obtain sucrose reinforcement or on cocaine induced hyperactivity. These findings show that Sal A, like other traditional KOPr agonists attenuates cocaine-induced drug seeking behavior

Does Al Jazeera make a difference? The framing of the Iranian election 2009 by Al Jazeera Arabic and CNN International

The election in Iran 2009 caused a serious crisis in Iranian society. The news media around the world reported about alleged manipulation, election fraud and other irregularities. “Where is my vote?” became the rallying cry of Iran’s opposition. This paper presents a crossnational comparative media analysis of news reporting on the Iranian election and the subsequent national and international reactions. It focuses on how a controversial political event was covered by two of the world´s leading television news broadcasters: Al Jazeera Arabic and CNN International, with a particular focus on Al Jazeera. Two theoretical frameworks were adopted: a contra-flow approach – Al Jazeera as an alternative source of news – as well as its role with respect to democratization. Two flagship news programs were analyzed over a six-week period in summer 2009. With quantitative framing analysis as the central methodology (using statistical factor analysis), we focused on the content of 66 television news stories

Single injection of novel kappa opioid receptor agonist salvinorin A attenuates expression of cocaine induced behavioral sensitization in rats

Kappa opioid receptor (KOPr) activation antagonizes many cocaine-related behaviors but adverse side effects such as sedation, dysphoria and depression limit their therapeutic use. Recently, salvinorin A (Sal A), a naturally occurring KOPr agonist, has been shown to attenuate cocaineinduced drug-seeking in a model of relapse in rats. The present study evaluated the effects of acute Sal A exposure on cocaine-induced hyperactivity and cocaine sensitization in rats. Acute treatment with the dose of Sal A that decreased drug-seeking in a previous study (0.3 mg/kg), significantly attenuated the expression of cocaine sensitization. This dose of Sal A failed to affect spontaneous locomotion or to produce a conditioned taste aversion to a novel-tasting saccharin solution. However, Sal A decreased climbing and swimming time and increased time spent immobile in the forced swim test. These findings indicate that Sal A, just like traditional KOPr agonists, attenuates cocaine-induced behavioral sensitization but does not produce the adverse effect of conditioned aversion, suggesting improved potential compliance. However, pro-depressive effects were also produced and these effects may limit the therapeutic potential

The placebo effect: from concepts to genes

Despite its initial treatment as a nuisance variable, the placebo effect is now recognized as a powerful determinant of health across many different diseases and encounters. This is in light of some remarkable findings ranging from demonstrations that the placebo effect significantly modulates the response to active treatments in conditions such as pain, anxiety, Parkinson’s disease, and some surgical procedures. Here, we review pioneering studies and recent advances in behavioural, neurobiological, and genetic influences on the placebo effect. Based on a previous developed conceptual framework, the placebo effect is presented as the product of a general expectancy learning mechanism in which verbal, conditioned, observational, and social cues are centrally integrated to change behaviours and outcomes. Examples of the integration of verbal and conditioned cues, such as instructed reversal of placebo effects are also incorporated into this model. We discuss neuroimaging studies that using well-established behavioral paradigms have identified key brain regions and modulatory mechanisms underlying placebo effects. Finally, we present a synthesis of recent genetics studies on the placebo effect, highlighting a promising link between genetic variants in the dopamine, opioid, serotonin, and endocannabinoid pathways and placebo responsiveness. Greater understanding of the behavioural, neurobiological, and genetic influences on the placebo effect is critical for evaluating medical interventions and may allow health professionals to tailor and personalize interventions in order to maximise treatment outcomes in clinical settings

The placebo effect: from concepts to genes

Despite its initial treatment as a nuisance variable, the placebo effect is now recognized as a powerful determinant of health across many different diseases and encounters. This is in light of some remarkable findings ranging from demonstrations that the placebo effect significantly modulates the response to active treatments in conditions such as pain, anxiety, Parkinson’s disease, and some surgical procedures. Here, we review pioneering studies and recent advances in behavioural, neurobiological, and genetic influences on the placebo effect. Based on a previous developed conceptual framework, the placebo effect is presented as the product of a general expectancy learning mechanism in which verbal, conditioned, observational, and social cues are centrally integrated to change behaviours and outcomes. Examples of the integration of verbal and conditioned cues, such as instructed reversal of placebo effects are also incorporated into this model. We discuss neuroimaging studies that using well-established behavioral paradigms have identified key brain regions and modulatory mechanisms underlying placebo effects. Finally, we present a synthesis of recent genetics studies on the placebo effect, highlighting a promising link between genetic variants in the dopamine, opioid, serotonin, and endocannabinoid pathways and placebo responsiveness. Greater understanding of the behavioural, neurobiological, and genetic influences on the placebo effect is critical for evaluating medical interventions and may allow health professionals to tailor and personalize interventions in order to maximise treatment outcomes in clinical settings

Crystallization and preliminary X-ray diffraction data for a purple acid phosphatase from sweet potato

Purple acid phosphatase from sweet potato is a homodimer of 110 kDa. Two forms of the enzyme have been characterized. One contains an Fe±Zn centre similar to that previously reported for red kidney bean purple acid phosphatase. Another isoform, the subject of this work, is the ®rst con®rmed example of an Fe±Mn-containing enzyme. Crystals of this protein have been grown from PEG 6000. They have unit-cell parameters a = b = 118.4, c = 287.4 A Ê and have the symmetry of space group P6522, with one dimer per asymmetric unit. Diffraction data collected using a conventional X-ray source from a cryocooled crystal extend to 2.90 A Ê resolution. The three-dimensional structure of the enzyme will provide insight into the coordination of this novel binuclear metal centre