Muscle-Specific Effective Mechanical Advantage and Joint Impulse in Weightlifting

Lifting greater loads during weightlifting exercises may theoretically be achieved through increasing the magnitudes of net joint impulses or manipulating the joints’ effective mechanical advantage (EMA). The purpose of this study was to investigate muscle-specific EMA and joint impulse as well as impulse-momentum characteristics of the lifter-barbell system across a range of external loads during the execution of the clean. Collegiate-level weightlifters performed submaximal cleans at 65, 75, and 85% of their 1-repetition maximum (1-RM) while data from a motion analysis system and a force plate were used to calculate lifter-barbell system impulse and velocity, as well as net extensor impulse generated at the hip, knee, and ankle joints and the EMA of the gluteus maximus, hamstrings, quadriceps, and triceps surae muscles. The results indicated that the lifter-barbell system impulse did not change as load increased, whereas the velocity of the lifter-barbell system decreased with greater load. In addition, the net extensor impulse at all joints increased as load increased. The EMA of all muscles did not, however, change as load increased. The load-dependent effects on the impulse-velocity characteristics of the lifter-barbell system may reflect musculoskeletal force-velocity behaviors, and may further indicate that the weightlifting performance is limited by the magnitude of ground reaction force impulse. In turn, the load-dependent effects observed at the joint-level indicated that lifting greater loads were due to greater net extensor impulses generated at the joints of the lower extremity and not greater EMAs of the respective extensor muscles. In combination, these results suggest that lifting greater external loads during the clean is due to the ability to generate large extensor joint impulses, rather than manipulate EMA

Transportation and Quality Adjusted Basis: Does the Law of One Price Hold for Feeder Cattle?

Beef cattle and calves are raised in all areas of the United States. Since beef cattle are scattered throughout the US, there are many different types of cattle with numerous different quality characteristics which are valued differently. Many calves raised until weaning age across the US are then sent to cattle feeding areas primarily located in Texas, Kansas, Colorado, and Nebraska. The prices that are offered for beef calves vary considerably based on quality and location. The theory of the law of one price suggests that prices in areas that trade should not differ by more than the cost of transportation. Implicit in the law of one price is that the product is homogenous in nature which is not the case with beef cattle. To test the law of one price, prices in the feeder cattle markets that trade should be equal after those prices have been adjusted for the cost of transportation and for differences in quality. Consequently, the objective of this thesis is to adjust prices for transportation costs and quality characteristics to determine if the law of one price holds in the US feeder cattle market. Data for this dissertation were obtained from Superior Livestock Auction in Brush, Colorado. The original data set included over 30,000 cattle lots sold throughout the entire US from 2004-2006 which includes valuable information such as price, breed, sex, number of head, days to delivery, location of sale, and destination of sale for each cattle lot. However, the data were narrowed to examine price and quality for weaned steer and heifer calves in the fall. This narrowed data set still contained 9,570 cattle lots which includes, specifically, steer and heifer calves, weighing between 450-700 pounds, and delivered in October and November. In order to determine if the law of one price holds for feeder cattle, first, a Hedonic regression analysis was used to determine the value of selected cattle, lot, and market characteristics. Second, the cost of transportation was calculated by figuring freight rates and animal shrinkage. Prices were then adjusted for freight rates and shrinkage values and for quality differences to determine if prices were equivalent across regions of the US and across states within a specific region of the US. Results from the Hedonic model showed that most cattle characteristics yielded expected results, and that there are differences in quality characteristics in cattle which affect the price. Further results revealed that the transportation adjusted prices varied by more than transportation costs, and that when adjusted for transportation costs, price were not the same across regions of the country. In combining quality characteristics and transportation costs, results also revealed that prices were different by region and by states within a region. Thus, based on the results from the data, it does not appear that the law of one price is upheld in the US feeder cattle market. The implications of the results are that there may be opportunities for arbitrage in feeder cattle markets. The results also indicate that cattle producers who are more distant from major cattle feeding areas receive prices for their calves that are higher than would be justified based on transportation costs and that producers who are closer to major cattle feeding areas receive prices for their calves that are less than should be expected based on transportation costs

Taking on the conversation: unresolved tensions in Conversationalism as a system

In his “On the System of Conversational Thinking: An Overview”, and in the talk he presented as part of the development of this paper (similarly titled), Jonathan Chimakonam attempts the first systematic fusion of the various components of Conversationalism. I refer to the ideas in the paper and the talk as ‘SCT’ (short for System of Conversational Thinking) in the comments below. In my response, I make an effort to largely ignore the comparative aspects of the work. In other words, I am not too concerned with the case Chimakonam makes to distinguish Conversationalism as a Philosophy separate from other styles and approaches such as analytic philosophy and hermeneutics. Instead, I make an effort to focus on Conversationalism in its own right and not in contrast to other systems. In doing so, my conversational stance is one of a critical proponent in the sense that I am broadly in favour of much of Conversationalism, but insist on rigorous scrutiny of its insights in the interests of making it stronger. My comments are thus focussed on potential problems with the internal coherence of the ideas contained in Chimakonam’s work, and my hope is to excavate them as areas for further discussion. To this end, I call attention to the following areas of conceptual dissonance in the explication of Conversationalism in SCT

Molecular and Biochemical Analysis of Phenolic Acid Decarboxylase from Brettanomyces Yeast Isolates

Many strains of Brettanomyces pose a major threat to the commercial brewing industry by producing phenolic off-flavors, while a few strains contribute desirable characteristics in unique beer styles. This genus of yeast possesses a two-step pathway that converts hydroxycinnamic acids (HCAs) to vinyl and ethyl derivatives that add unwanted flavors and aromas to the final beverage. This project focused on analyzing Brettanomyces yeast isolates for variation in phenolic acid decarboxylase activity (PAD), which catalyzes the first step in the pathway. Each strain was grown in the three different common HCAs (ferulic acid, p-coumaric acid, caffeic acid) to understand each strain’s reactivity to the compound. Strains displayed variation in their PAD activity and growth in HCAs. Most good brewing strains were highly sensative to pcoumaric acid, and displayed significant lags in their growth in p-coumaric and ferulic acid. All strains were highly resistant to caffeic acid. These data show some trends towards differences in good brewing strains and may lead to easier identification methods for yeast strains that may be good for brewing

Optimization of a boundary element approach to electromagnet design with application to a host of current problems in Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) has proven to be a valuable methodological approach in both basic research and clinical practice. However, significant hardware advances are still needed in order to further improve and extend the applications of the technique. The present dissertation predominantly addresses gradient and shim coil design (sub-systems of the MR system). A design study to investigate gradient performance over a set of surface geometries ranging in curvature from planar to a full cylinder using the boundary element (BE) method is presented. The results of this study serve as a guide for future planar and pseudo-planar gradient systems for a range of applications. Additions to the BE method of coil design are developed, including the direct control of the magnetic field uniformity produced by the final electromagnet and the minimum separation between adjacent wires in the final design. A method to simulate induced eddy currents on thin conducting surfaces is presented. The method is used to predict the time-dependent decay of eddy currents induced on a cylindrical copper bore within a 7 T MR system and the induced heating on small conducting structures; both predictions are compared against experiment. Next, the method is extended to predict localized power deposition and the spatial distribution of force due to the Lorentz interaction of the eddy current distribution with the main magnetic field. New methods for the design of actively shielded electromagnets are presented and compared with existing techniques for the case of a whole-body transverse gradient coil. The methods are judged using a variety of shielding performance parameters. A novel approach to eliminate the interactions between the MR gradient system and external, non-MR specific, active devices is presented and its feasibility is discussed. A completely new approach to shimming is presented utilizing a network of current pathways that can be adaptively changed on a subject-by-subject basis and dynamically controlled. The potential benefits of the approach are demonstrated using computer simulations and a prototype coil is constructed and tested as a proof-of-principle

A Collaborative Visualization Framework Using JINI™ Technology

It is difficult to achieve mutual understanding of complex information between individuals that are separated geographically. Two well-known techniques commonly used to deal with this difficultly are collaboration and information visualization. This thesis develops a generic flexible framework that supports both collaboration and information visualization. It introduces the Collaborative Visualization Environment (COVE) framework, which simplifies the development of real-time synchronous multi-user applications by decoupling the elements of collaboration from the application. This allows developers to focus on building applications and leave the difficulties of collaboration (i.e., concurrency controls, user awareness, session management, etc.) to the framework. The framework uses an object sharing approach to share information and views between participants in a collaborative session. This approach takes advantage of several Java technologies (i.e., JavaBeans™, Jini™, and JavaSpaces™). JavaBeans™ establish a well-known standard for applications to operate within the framework. Jini™ services provide framework stability and enable code sharing across the network. Objects are shared between remote clients through the JavaSpaces™ service

Design and Construction of a Programmable Electroporation system for Biological Applications

Studies into electroporation have grown rapidly in biotechnology and medicine in recent years. This paper presents the design and construction of a low cost programmable electroporation system for biological applications. The system consists of a control module, a pulse generation circuit and a high voltage switch using a power MOSFET. The programmable electroporation has been designed, developed and tested. Using a standard commercial electroporation cuvette, it is possible to generate electric fields of 100 to 1000V/cm with programmed pulse lengths of 10?sec to 20msec. The system was evaluated with Hela cells and propidium dye to evaluate transfection rates under a variety of electroporation conditions. Initial results showed that the electroporation system achieved a peak cell transfection efficiency of 48.74% at 600V/cm with pulse lengths of 10 ms

Transportation and Quality Adjusted Basis: Does the Law of One Price Hold for Feeder Cattle?

Feeder calf prices are examined from a national video auction sales from 2004-2006. Many cattle, lot, and market characteristics significantly impact feeder cattle basis. Auction prices were adjusted for quality differences and for transportation costs and compared across regions. Basis was significantly different after the adjustment from region to region.feeder cattle prices, law of one price, video auctions, Demand and Price Analysis, Farm Management, Livestock Production/Industries, Marketing,

Patterns of Barbell Acceleration during the Snatch in Weightlifting Competition

The purpose of this study was to determine the association between weightlifting performance and vertical barbell acceleration patterns. Barbell kinematic time-series data were tracked from 18 snatches from six weightlifters during a regional weightlifting competition. These data were used to calculate vertical barbell accelerations. Time-series data were normalised to 100% of lift phase, defined as the time interval between barbell lift-off and maximum height of the barbell during each snatch lift. The time-series data were then entered into a pattern recognition algorithm that extracted principal patterns and calculated principal pattern scores. Body mass-normalised lift weight, which was used to quantify weightlifting performance, was significantly correlated (r = 0.673; P = 0.033) with a pattern that captured a difference in peak vertical barbell acceleration between the transition and the second pull phase. This correlation indicated that barbell acceleration profiles of higher weight snatch lifts were characterised by smaller decreases in acceleration during the second knee bend and smaller peak acceleration during the second pull phase. Weightlifting coaches and sports scientist should monitor and track vertical acceleration of the barbell, with focus on acceleration profiles that limit (1) deceleration during the transition phase between the first and second pull and (2) peak acceleration during the second pull phase of the snatch

ASSOCIATIONS BETWEEN GROUND REACTION FORCES AND BARBELL ACCELERATIONS IN WEIGHTLIFTING

The purpose of this study was to investigate associations between vertical ground reaction forces and vertical barbell accelerations during the snatch. Barbell kinematic and force plate kinetic data were collected during a weightlifting competition. Time-series data were normalized to 100% of lift phase and were entered into a pattern recognition algorithm that extracted principal patterns and calculated principal pattern scores. Significant associations indicate that a smaller, and temporally shorter, decrease in ground reaction forces during the transition phase is associated with a smaller decrease in barbell acceleration during the transition phase and a smaller peak barbell acceleration during the second pull phase. In order to optimize barbell acceleration, weighlifters may need to ensure a quick transition between the first and second pull