kappa-deformed Spacetime From Twist

We twist the Hopf algebra of igl(n,R) to obtain the kappa-deformed spacetime coordinates. Coproducts of the twisted Hopf algebras are explicitly given. The kappa-deformed spacetime obtained this way satisfies the same commutation relation as that of the conventional kappa-Minkowski spacetime, but its Hopf algebra structure is different from the well known kappa-deformed Poincare algebra in that it has larger symmetry algebra than the kappa-Minkowski case. There are some physical models which consider this symmetry. Incidentally, we obtain the canonical (theta-deformed) non-commutative spacetime from canonically twisted igl(n,R) Hopf algebra.Comment: revtex4, 7 pages, 1 figure, minor changes, references adde

THE EFFECTS OF WEARING ROLLER SHOES ON GROUND REACTION FORCE CHARACTERISTICS DURING WALKING

Roller shoes have become increasingly popular among children and it features retractable wheels which allowing the user to walk or roll without changing the footwear. Maintaining balance during forward walking with roller shoes is not an easy task. To prevent falling backward, the user needs to lock the knees and tighten the ankles and thighs while the upper body is slightly leaning forward. Constant walking with roller shoes forces the user to walk in a manner much different from normal gait. Prolonged exposure to un-natural stresses on human body forces our body to evolve by strengthening those incorrect, and temporary functions (Clement et aI., 1981). For children, the chronic stress may lead to serious injuries in the lower extremity later in life. If any potential' of injury exists in a movement it is critical to examine the associated forces that may lead to injury. To the best of our knowledge, the effects of wearing roller shoes on ground reaction forces (GRF) characteristics have rarely been studied, especially in the youth population. Thus, the purpose of this study was to compare GRF characteristics during walking wearing jogging and roller shoes

Noncommutative Field Theory from twisted Fock space

We construct a quantum field theory in noncommutative spacetime by twisting the algebra of quantum operators (especially, creation and annihilation operators) of the corresponding quantum field theory in commutative spacetime. The twisted Fock space and S-matrix consistent with this algebra have been constructed. The resultant S-matrix is consistent with that of Filk\cite{Filk}. We find from this formulation that the spin-statistics relation is not violated in the canonical noncommutative field theories.Comment: 13 pages, 1 figure, minor changes, add reference

Fracture of a Tempofilter II: an Initial Case Report

Tempofilter II is a device that is used for pulmonary embolism prophylaxis. Since the appearance of the Tempofilter II following withdrawal of the Tempofilter I, it has been reported that the Tempofilter II is safe, effective and useful. Here we report on the first case of a fracture of one leg of the filter and this leg was embedded in the inferior vena cava wall in a 62-year-old man with deep vein thrombosis

TIBIO-FEMORAL JOINT FORCES DURING THE LANDING PHASE OF DIFFERENT TYPES OF VERTICAL JUMP

The purpose of this study was to compare the tibio-femoral contact forces during the landing phases of 8 different types of vertical jump (squat, countermovement, hop approach and drop jumps each with and without the use of arms). Data were collected from eight males and eight females. Two S-VHS camcorders and a force platform were used to obtain the 3-D kinematics and kinetics of the knee joint. Activities of selected muscles spanning the knee joint were monitored using surface electromyographic (EMG) techniques. The EMG-assisted optimization model was used to estimate the tibio-femoral joint forces. The peak compressive contact forces ranged from 3-5 body weight (SW) and from 2.5-3.7 SW for the males and females, respectively. These loads seldom fell within the range that is considered to be damaging to the cartilage at the knee