PEAK VELOCITY OF NORDIC SKI DOUBLE POLE TECHNIQUE

One of the event styles in cross-country skiing is the classic technique in which the skis move in groomed tracks. Double poling is a technique used under the classic skiing style, and is defined as when the upper body provides most of the propulsion via bilateral pole pushes. Double poling during classic cross-country skiing has become more popular in the past twenty years. It has also been shown to have strong correlations with increased race speed (Smith, Fewster, & Braudt, 1996). Maximal velocity considers an overall velocity of the movements, but does not specify at which point during the poling phase that peak velocity occurs. By breaking a movement down into its components one may be able to critique technique more specifically. This study examined the point at which peak linear velocity occurred during the double poling cycle time in Nordic stand-up and sit-down skiing

ELECTROMYOGRAPHICAL ANALYSIS OF DOUBLE POLE ERGOMETRY: STANDING VS. SITTING

This study assessed the difference in stand-up athlete’s muscle activity of the rectus femoris in standing and sitting using a double pole ergometer. Five subjects participated in two technique specific peak VO2 tests, and a percentage of the maximum scores were used to determine stages for analysis of the electromyography data that was collected. An ANOVA revealed a significant difference in electromyographical activity between ski position and stage using a pre-determined alpha level of

ELECTROMYOGRAPHICAL ANALYSIS OF DOUBLE POLE ERGOMETRY: STANDING VS. SITTING.

This study assessed the difference in stand-up athlete’s muscle activity of the rectus femoris in standing and sitting using a double pole ergometer. Five subjects participated in two technique specific peak VO2 tests, and a percentage of the maximum scores were used to determine stages for analysis of the electromyography data that was collected. An ANOVA revealed a significant difference in electromyographical activity between ski position and stage using a pre-determined alpha level of

Rapidly inducible, genetically targeted inactivation of neural and synaptic activity in vivo

Inducible and reversible perturbation of the activity of selected neurons in vivo is critical to understanding the dynamics of brain circuits. Several genetically encoded systems for rapid inducible neuronal silencing have been developed in the past few years offering an arsenal of tools for in vivo experiments. Some systems are based on ion-channels or pumps, others on G protein coupled receptors, and yet others on modified presynaptic proteins. Inducers range from light to small molecules to peptides. This diversity results in differences in the various parameters that may determine the applicability of each tool to a particular biological question. Although further development would be beneficial, the current silencing tool kit already provides the ability to make specific perturbations of circuit function in behaving animals

An analysis of the acoustic cavitation noise spectrum: The role of periodic shock waves

Research on applications of acoustic cavitation is often reported in terms of the features within the spectrum of the emissions gathered during cavitation occurrence. There is, however, limited understanding as to the contribution of specific bubble activity to spectral features, beyond a binary interpretation of stable versus inertial cavitation. In this work, laser-nucleation is used to initiate cavitation within a few millimeters of the tip of a needle hydrophone, calibrated for magnitude and phase from 125 kHz to 20 MHz. The bubble activity, acoustically driven at f0 = 692 kHz, is resolved with high-speed shadowgraphic imaging at 5 × 106 frames per second. A synthetic spectrum is constructed from component signals based on the hydrophone data, deconvolved within the calibration bandwidth, in the time domain. Cross correlation coefficients between the experimental and synthetic spectra of 0.97 for the f 0/2 and f 0/3 regimes indicate that periodic shock waves and scattered driving field predominantly account for all spectral features, including the sub-harmonics and their over-harmonics, and harmonics of f 0

22q13.32 Deletion and Duplication and Inversion in the Same Family: A Rare Occurrence

Chromosome 22q13.3 deletion syndrome is a well-recognized cause of global developmental delay, while duplication of the same chromosome is a rare occurrence. The presence of both abnormalities in the same family has never been reported, to our knowledge. We report a rare occurrence of 22q13.3 duplication and 22q13.3 deletion in siblings, as a consequence of a mother's inversion on her 22nd chromosome (p13;q13.32). A 6 year old male was noted in infancy to have mild global developmental delay without dysmorphic features. His genetic testing revealed he had 22q13.3 duplication to the terminus. His 4 year old brother was noted in early infancy to have severe global developmental delay and dysmorphic features related to 22q13.3 deletion to the terminus. Their mother had a long inversion on her 22nd chromosome. Genetic tests for their father and eldest brother were unremarkable. The mother's inversion may rearrange to form 22q duplication or deletion when passed on to children. The chance of a child born with a chromosome imbalance is as high as 50%

Monitoring synaptic transmission in primary neuronal cultures using local extracellular stimulation

Various techniques have been applied for the functional analysis of synaptic transmission in Cultured neurons. Here, we describe a method of studying synaptic transmission in neurons cultured at high-density from different brain regions such as the cortex, striatum and spinal cord. We use postsynaptic whole-cell recordings to monitor synaptic Currents triggered by presynaptic action potentials that are induced by brief stimulations with a nearby extracellular bipolar electrode. Pharmacologically isolated excitatory or inhibitory postsynaptic currents can be reliably induced, with amplitudes, synaptic charge transfers, and short-term plasticity properties that are reproducible from culture to culture. We show that the size and kinetics of pharmacologically isolated inhibitory postsynaptic Currents triggered by single action potentials or stimulus trains depend on the Ca2+ concentration, temperature and stimulation frequency. This method can be applied to study synaptic transmission in wildtype neurons infected with lentiviruses encoding various components of presynaptic release machinery, or in neurons from genetically modified mice, for example neurons carrying floxed genes in which gene expression can be acutely ablated by expression of Cre recombinase. The preparation described in this paper should be useful for analysis of synaptic transmission in inter-neuronal synapses formed by different types of neurons. (c) 2006 Elsevier B.V. All rights reserved

Deterministic Partial Differential Equation Model for Dose Calculation in Electron Radiotherapy

Treatment with high energy ionizing radiation is one of the main methods in modern cancer therapy that is in clinical use. During the last decades, two main approaches to dose calculation were used, Monte Carlo simulations and semi-empirical models based on Fermi-Eyges theory. A third way to dose calculation has only recently attracted attention in the medical physics community. This approach is based on the deterministic kinetic equations of radiative transfer. Starting from these, we derive a macroscopic partial differential equation model for electron transport in tissue. This model involves an angular closure in the phase space. It is exact for the free-streaming and the isotropic regime. We solve it numerically by a newly developed HLLC scheme based on [BerCharDub], that exactly preserves key properties of the analytical solution on the discrete level. Several numerical results for test cases from the medical physics literature are presented.Comment: 20 pages, 7 figure

Toward the neural implementation of structure learning

Despite significant advances in neuroscience, the neural bases of intelligence remain poorly understood. Arguably the most elusive aspect of intelligence is the ability to make robust inferences that go far beyond one's experience. Animals categorize objects, learn to vocalize and may even estimate causal relationships -all in the face of data that is often ambiguous and sparse. Such inductive leaps are thought to result from the brain's ability to infer latent structure that governs the environment. However, we know little about the neural computations that underlie this ability. Recent advances in developing computational frameworks that can support efficient structure learning and inductive inference may provide insight into the underlying component processes and help pave the path for uncovering their neural implementation