A note on the Tits systems of Kac-Moody Steinberg groups

Let G(H) be the Chevalley (Steinberg) Kac-Moody group of the Kac-Moody Lie algebra L. If σ is the canonical homomorphism of H onto G. and [BG. NG] is the Tits system in G, them (σ-1(BG), σ-1(NG)) is a Tits system in the Weyl-simple subgroup of H

Barns egna platser på skolgården

Alla barn i Sverige har rätt till fri skolgång, vilket gör att skolan blir en stor del av barns vardag och har en betydande roll för deras välmående och utveckling. För många barn är skolgården den plats som de lättast kan använda när de vill spendera tid utomhus med vänner eller på egen hand. Syftet med studien har varit att ur barnens perspektiv ta reda på hur de upplever sin skolgård som socialt rum med fokus på möjligheterna att hitta egna platser. Med hjälp av gåturer tillsammans med barn i förskoleklass och andra klass har en grundskolas skolgård studerats. Resultatet visar att det för den bebyggda delen av skolgården fannas förutbestämda normer för aktiviteten med fokus på regellek, sporter och andra former av fysiska aktiviteter, något som skapade utanförskap för vissa barn. På centrala delar av skolgården kunde barn uppleva att de inte hade möjlighet välja vad de skulle göra. De uttryckte behov av platser där de kunde vara mer i kontroll och forma både sin aktivitet och platsen. Bristen på platser som barnen själva kunde forma gjorde att individer kände sig utanför. När barnen skapade sina egna platser valdes miljöer som befann sig i eller angränsade till natur och det var platser som barnen själva kunde bygga upp och rama in. Grönskan bidrog till barnens möjlighet att själva forma platsen och välja vilka typer av aktiviteter de skulle utföra. I denna miljö, till skillnad från den bebyggda skolgården, var inte typen av aktivitet förbestämd genom utformningen och elever med olika önskemål och förutsättningar kunde lättare umgås med varandra. Studien pekar på vikten av skolgårdar utformas så att barn kan skapa egna platser och aktiviteter. Hur naturmark, vegetation och löst material utgör viktiga komponenter i en sådan designAll children Sweden have the right to free education, which means that the school becomes a major part of children's everyday lives and has a significant role in their well-being and development. For many children, the schoolyard is the place they can most easily use when they want to spend time outdoors with friends or on their own. The purpose of this study was to find out from the children's perspective how they perceive their schoolyard as a social space with a focus on the opportunities to find their own places. With the help of walks together with children in preschool and second class, an elementary school schoolyard has been studied. The result shows that there were predetermined norms on the type of activities performed in the built part of the school yard, these norms were rules, sports or activities of a physical nature which caused some children feel left out. In central parts of the schoolyard the children did not feel that they had the same opportunity to determine activity. They expressed a need for places where they could be more in control and shape both their activity and the place. When the children created their own places, places were chosen that were in some way bounded by nature and which the children themselves could limit and build up. This due to the fact that the greenery offered the children an opportunity to choose for themselves what types of activities they wanted to do there. In this environment, unlike the built schoolyard, the type of activity was not predetermined by the design of the environment. Here children could perform different activities in one and the same place, which made it easier for children with different wishes and conditions to socialize with each other. The study points to the importance of school yards being designed so that children can create their own places and activities. How natural land, vegetation and loose material are important components of such a desig

Evaluation of soil liquefaction from surface analysis

AbstractIn this paper we describe how some techniques for estimating shallow shear wave velocity profilesobtainedfrommeasurementsofambient vibrations and from artificially generated waves can be used to assess sand liquefaction potential. The measurements are easy, quick and more economical than most other methods. The passive Microtremor Analysis Method (MAM) and the active Multichannel Analysis of Surface Waves (MASW) have only recently been adopted for liquefaction studies. We propose a method that was applied in the valley of Mexicali to characterize soil in terms of shear wave velocity to assess liquefaction potential; our results display its advantages

Optical accuracy: Study of commercially available non-prescription golf sun eyewear

Background: Visual benefits from sun eyewear are well documented, however golf has been a sport slow to embrace the use of sun eyewear. This study subjectively and objectively investigated the amount of induced prism in four popular brands of commercially available golf sun eyewear. Methods: 40 subjects evaluated the amount of perceived induced prism in four pairs of golf sun eyewear under monocular and binocular conditions in both primary gaze and 30 degrees lateral gaze using a golf ball on a putting green. Prismatic deviation for each eyewear was also measured objectively in primary gaze and 30 degrees lateral gaze using a custom-built laser headform. Results: Average prismatic deviation as reported by the subjects was found to be significant from zero in many of the gaze positions. Of the 12 possible combinations of gaze position and deviation directions, the Bolle eyewear had significant prismatic jump in 6, the NYX eyewear in 4, and the Nike and Oakley eyewear both in 2. Objectively in primary gaze, using a ranking system, the Nike eyewear ranked highest, the NYX ranked second and the Oakley and Bolle ranked lowest. In 30 degree lateral gaze the Nike eyewear ranked highest, the Oakley eyewear ranked second, the NYX eyewear ranked third, and the Bolle eyewear ranked lowest. Conclusions: Sun eyewear can be used to both protect the eye and to enhance the golfer\u27s game under bright conditions during the visually demanding game of golf. Significant amounts of prism were found in both subjective and objective measures. It may be beneficial to the golfer to use sun eyewear that induces the least amount of prismatic deviation, however the impact of this induced prism on overall golf performance should be assessed in future studie

Uso del sistema de corrección coplanar en Escoliosis Neuromuscular. Comparación con la técnica de desrotación apical y análisis de las complicaciones y comorbilidades

Tesis para el grado de Doctor en medicina clínica, con mención Tesis InternacionalThe concept of neuromuscular scoliosis includes a wide variety of pathologies associated with both the nervous and muscular systems they represent a challenging population to treat. As such, determining the correct surgical plan can oftentimes be complex given the multitude of variables to consider, ranging from clinical (i.e., ventilatory function, comorbidities) to biomechanical (i.e., pelvic obliquity, curve magnitude and rigidity, bone quality, sitting balance. Currently, no clear patterns of neuromuscular curvatures have been described in the literature and there remains a lack of consensus on the best technique to achieve a balanced posture. In the setting of neuromuscular scoliosis, a surgeon has multiple corrective techniques at his or her disposal to select from. The use of traction, either preoperatively or intraoperatively, has been previously reported in patients with high grade curves. Combined approaches have a role in correction when treating patients with rigid curves and permit better control of pelvic obliquity; however, they are also associated with increased OR time and EBL. The posterior-only approach on the other hand has been associated with fewer complications and thus remains the preferred technique for a majority of spine surgeons. The Vertebral Coplanar Alignment (VCA) technique takes into consideration aspects of vertebral anatomy that the Apical Derotation (AD) techniques do not. Because the medial cortex of the vertebral body is wider and more resistant than the lateral cortex, this allows for more anchor points during derotation for a better distribution of forces. Furthermore, VCA takes advantage of the fact that children have stronger ligaments and more elastic bones by relying on this strong attachment to guide correction. By relocating the normal coplanar axis into a single plane, translation and derotation can be achieved in one gesture. With such a heterogeneous group of disorders, it is difficult to establish guidelines for preoperative planning, surgery, and postoperative treatment. Although patients are evaluated individually, the identification of shared characteristics can be valuable for treatment algorithms. Complications in neuromuscular scoliosis surgery are difficult to anticipate and no association has been studied between perinatal comorbidities, preoperative evaluation, surgical parameters, and postoperative complications. One of the complications is profuse bleeding, the mechanisms of addressing this issue are either replacing blood, involving autotransfusions, cell saver and allotransfusions, all which are potentially associated with complications, increase procedures and higher costs, or saving blood. In recent years tranexamic acid has taken precedence in this matter.Existen múltiples consideraciones en escoliosis neuromuscular, grandes deformidades, curvas rígidas, mala calidad ósea y oblicuidad pélvica. No hay consenso en cual es la mejor técnica quirúrgica para seguir con estos pacientes. La técnica de desrotación coplanar considera tres aspectos, no evaluados previamente: que la corteza medial del pedículo es mas gruesa que la corteza lateral, el aumento de los puntos de torque permite una mejor distribución de las fuerzas y el uso de ligamentotaxis como coadyuvante en la maniobra de reducción. Si logramos realinear la coplanaridad normal, la traslación y desrotación vertebral son posibles en un solo gesto quirúrgico. Las comorbilidades y complicaciones son considerable en este grupo de pacientes y difíciles de predecir. Una de las complicaciones mas importantes es el sangrado masivo, dentro de los mecanismos para enfrentarlo, está el uso de acido tranexámico, habitualmente utilizado de manera endovenosa, se ha explorado también su uso tópico. OBJETIVO: Comparar la capacidad de corrección de el Sistema de desrotación coplanar (DC) versus el de desrotación apical (DA) en pacientes pediátricos con escoliosis neuromuscular. Como objetivo secundario, determinar los factores predictores de riesgo de complicaciones en escoliosis neuromuscular, con énfasis en el sangrado y el uso de acido tranexámico endovenosos y tópico para su prevención.MedicinaCiencias de la Salu

The Evolution of Geotechnical Earthquake Engineering Practice in North America: 1954-1994

This paper traces the evolution of geotechnical earthquake engineering practice in North America from 1954 to 1994. The development of the state-of-the-art has been shaped strongly by four areas of practice: assessment of seismic hazard, estimation of liquefaction potential, seismic response analysis of earth structures and seismic safety evaluation and remediation of existing dams with potentially liquefiable zones. Evolution of practice in each of these areas will be traced and the current state-of-the-art evaluated. Present capabilities in practice will be illustrated by examples from the areas of seismic response of dams, liquefaction potential and seismic safety evaluation and remediation of potentially liquefiable embankment dams

Methadone-induced mortality in the treatment of chronic pain: Role of QT prolongation

Methadone is increasingly prescribed for chronic pain, yet the associated mortality appears to be rising disproportionately relative to other opioid analgesics. We review the available evidence on methadone-associated mortality, and explore potential pharmacokinetic and pharmacodynamic explanations for its greater apparent lethality. While methadone shares properties of central nervous system and respiratory depression with other opioids, methadone is unique as a potent blocker of the delayed rectifier potassium ion channel (IKr). This results in QT-prolongation and torsade de pointes (TdP) in susceptible individuals. In some individuals with low serum protein binding of methadone, the extent of blockade is roughly comparable to that of sotalol, a potent QT-prolonging drug. Predicting an individual’s propensity for methadone-induced TdP is difficult at present given the inherent limitations of the QT interval as a risk-stratifier combined with the multifactorial nature of the arrhythmia. Consensus recommendations have recently been published to mitigate the risk of TdP until further studies better define the arrhythmia risk factors for methadone. Studies are needed to provide insights into the clinical covariates most likely to result in methadone-associated arrhythmia and to assess the feasibility of current risk mitigation strategies