In diesem Beitrag wird der Neuaufbau eines Versuchsstandes beschrieben, der zur Untersuchung magnetischer Eigenschaften von ferromagnetischen Werkstoffen dient. Angefangen bei der Notwendigkeit eines solchen Versuchsstandes werden der Aufbau, die Komponenten sowie die Besonderheiten beschrieben und erste Messergebnisse nach der Inbetriebnahme gezeigt. / This paper describes the new construction of a test bench used to investigate magnetic properties of ferromagnetic materials. Starting with the necessity of a test bench of this kind, the setup, the components and the special features are described and the first measurement results are shown after commissioning.

In an attempt to improve aerobic and anaerobic performance, athletes and fitness enthusiasts consume a variety of supplements. Because of this, energy drinks are quickly becoming more and more popular every day. Despite its highly addictive nature, caffeine, which is the main active ingredient in energy drinks, is gaining recognition as an ergogenic aid. However, due to the many factors that affects the action of caffeine, and because the research on caffeine and anaerobic performance is limited, the potential for studying energy drinks and anaerobic performance is quite large. PURPOSE: To determine if a commercially available energy drink has any ergogenic effects on lower body and upper body resistance exercise performance. METHODS: In a block randomized, double-blind, placebo-controlled, crossover study thirteen recreationally trained male and female volunteers (mean ± SD age = 22.5 ± 3.4 years) performed 4 sets of the leg press and 4 sets of the bench press exercises (at 80% of 1 RM with all sets separated by 2 minutes). Acting as their own controls, participants were tested on each dependent variable (i.e., bench press total volume, leg press total volume and total workout volume) twice, after ingesting a Venom® Energy Drink and after ingesting a placebo drink. RESULTS: Data were tested via a dependent samples t-test with p value set at < 0.05. No significant differences were found for any of the three dependent variables. DISCUSSION: The major finding of this study is that consumption of a Venom® Energy Drink does not produce an ergogenic effect by improving anaerobic exercise performance when the exercises are performed forty-five minutes following ingestion. Future studies should focus more on examining the factors behind the actions of caffeine. More specifically, the exercise performed, the training status of the participants, individual differences of the participants, and the dose of caffeine.

Prior to major competitions, athletes often use a peaking protocol such as tapering or training cessation to improve performance. The majority of the current literature has focused on endurance-based sports such as swimming, cycling, and running to better understand how and when to taper or use training cessation to achieve the desired performance outcome. However, evidence regarding peaking protocols for strength and power athletes is lacking. Current limitations for peaking maximal strength is that many studies do not provide sufficient details for practitioners to use. Thus, when working with athletes such as powerlifters, weightlifters, throwers, and strongman competitors, practitioners must use trial and error to determine the best means for peaking rather than using an evidence-based protocol. More specifically, determining how to peak maximal strength using data derived from strength and power athletes has not been established. While powerlifting training (i.e., back squat, bench press, deadlift) is used by strength and power athletes up until the final days prior to a competition, understanding how to peak maximal strength relative to powerlifting performance is still unclear. Thus, the purpose of this study was to review the literature on tapering and training cessation practices relative to peaking powerlifting performance.

Physical bench top experiments are performed to validate and complement ongoing computational fluid dynamics (CFD) analyses of ventricular assist device (VAD) circulation. VADs are used in patients whose hearts do not function to their maximum potential due advanced stages of heart disease and, consequently, are unable to adequately supply blood to the systemic circulation. VADs are commonly utilized as a bridge-to-transplantation, meaning that they are implanted in patients while waiting for a heart transplant. In such cases of long term utilization of VADs, it has been reported in the literatures that thrombo-embolic cerebral events occur in 14-47% of patients over the period of 6 to 12 months. This is a result of thrombus forming despite the use of anticoagulants and advances in VAD design. Accepting current rates of thrombo-embolisms, the main objective of the project is to identify and propose an optimal surgical cannula implantation orientation aimed at reducing the rate of thrombi reaching the carotid and vertebral arteries and thus reduce the morbidity and mortality rate associated with the long term use of VADs to patients suffering from advanced heart failure. The main focus of the experiment is on the physical aspect using a synthetic anatomically correct model constructed by rapid prototyping of the human aortic arch and surrounding vessels. Three VAD cannula implantation configurations are studied with and without bypass to the left carotid artery or to the Innominate artery with ligation of the branch vessel at its root. A mixture of water and glycerin serves to match blood viscosity measured with a rotating cone-plate viscometer. The Reynolds number in the ascending aorta is matched in the flow model. A closed loop mock circulatory system is then realized. In order to match the Reynolds number in the ascending aorta and LVAD cannula with that of the CFD model, a volumetric flow rate of 2.7 liters per minute is supplied through the synthetic VAD cannula and 0.9 liter per minute is supplied to the ascending aorta. Flow rates are measured using rotary flow meters and a pressure sensor is used to ensure a mean operating pressure of 100 mmHg is maintained. Synthetic acrylic blood iv clots are injected at the inlet of the VAD cannula and they are captured and counted at the vertebral and carotid arteries. The sizes of the thrombi simulated are 2, 3.5 and 5 mm which are typical of the range of diameters encountered in practice. Nearly 300 particles are released over 5 separate runs for each diameter, and overall embolization rates as well as individual embolization rates are evaluated along with associated confidence levels. The experimental results show consistency between CFD and experiment. Means comparison of thromboembolization rates predicted by CFD and bench-top results using a Z-score statistic with a 95% confidence level results in 22 of 24 cases being statistically equal. This study provides confidence in the predictive capabilities of the bench-top model as a methodology that can be utilized in upcoming studies utilizing patient-specific aortic bed model.

A surrogate arm model was created that is capable of being used for oscillometry. This model is capable of being used as a bench top model for blood pressure cuff devices. The arm consists of endplates and internal supports that are 3D printed with ABS, a silicone rubber outer sleeve, and interchangeable arteries made from two silicone rubber strips glued together at the edges. The interchangeable arteries have varying compliances that can be used as different inputs for oscillometric testing. A process was established to measure the artery compliances with a curve fit correlation of 0.95. However, testing revealed that this artery compliance relationship might not be an accurate representation of the artery compliance while it is in the surrogate arm system. A blood pressure cuff was also used with the surrogate arm model to measure changes in artery volume. Testing with the surrogate arm revealed a blood pressure cuff was capable of measuring artery volume changes of 2mL to 8mL consistently within 3.28% error. Volume changes of 1mL were unable to be repeatable measured accurately with a blood pressure cuff.

An excised animal larynx model has been used in many studies to better understand the physiological and anatomical properties of the human larynx. One difference between an ex vivo model and an in vivo model is that ion loss occurs postmortem. To compensate for this in the excised model, researchers most commonly use a preservation method that includes completely submerging the specimen in isotonic saline (0.9% Na+Cl-) and then flash freezing it in liquid nitrogen. The flash freezing method allows researchers to maintain the integrity of the structures while also being able to gather specimens as they become available. Not enough research has been done to understand the effects of a preservation method on the outcomes of the study. Additionally, no common method has been established for preservation across studies to ensure that results are not being influenced by this variable. This prospective, mixed experimental design study includes three groups, a control group and two experimental groups. The control group consisted of 10 bench-mounted porcine larynges that were soaked in isotonic saline and flash frozen with liquid nitrogen. Prior to the experiment, the frozen larynges were thawed overnight before trials. The other two groups consisted of 10 bench-mounted porcine larynges each; these larynges were soaked in either isotonic saline or Ringers solution, a balanced fluid used in vivo to counteract dehydration. Larynges from these two groups were kept fresh and stored in a refrigerator overnight before trials. On the day of experimentation, each larynx was mounted on a bench top setup including three micropositioners to stabilize, adduct, and elongate the vocal folds. All the larynges were connected to a pseudolung via the trachea and humidified air was passed through to the vocal folds until phonation was achieved. Phonatory trials consisted of brief phonation followed by 5-minute desiccation intervals until phonation was no longer achieved. Phonation threshold flow (PTF), defined as the flow observed at the onset of phonation, was observed during each phonation trial; and flow values were compared within and between groups. Statistically significant differences were found between the Ringers group and the fresh saline group as well as between the Ringers group and the frozen saline group, indicating that PTF is influenced by the larynx preservation method.

A study was performed on a recently developed prototype of the Yong-Geddes surrogate arm design to collect compliance data of the various system components and determine the accuracy of measurements made through the bench top model. The study was performed to perceive the effectiveness of the model as a tool for validating non-invasive blood pressure detection monitors. Three stages of testing were performed to gather pressure and volume data from an artificial artery component, a sphygmomanometer, and the surrogate arm system to produce compliance estimations. Mathematical equations from supported arterial hemodynamics studies and clinical trials were applied to the pressure and volume data. Dr. Drzewiecki’s equation for arterial compliance was capable of predicting the region of the highest compliance of the artificial artery and produced an overall value of 38.81% for the data. A second degree inverse polynomial was developed and modeled the sphygmomanometer compliance measurements with a of 99.09%. Significant error was observed throughout all stages of the compliance testing, which was attributed to factors such as excessive noise due to faulty data collection equipment and irreparable leaks in the fluid flow system.

Subglottic stenosis (SGS) is an abnormal narrowing of the airway at the level of the cricoid cartilage, above the first tracheal ring and immediately beneath the vocal folds. Individuals with SGS experience a reduction in their ability to breathe as well as adverse effects on voice function. SGS can result from a variety of causes with the type of treatment depending on stenosis severity. Surgical techniques such as laryngotracheal and cricotracheal reconstruction are beneficial for airway maintenance; however, these procedures have resulted in negative effects on voice production. On the other hand, there are patients with SGS who do not require surgery and still experience voice problems. The purpose of this study was to quantify the effects of SGS on vocal fold vibration using an excised larynx benchtop mechanical model. Using a within-subjects repeated measures design, nine porcine larynges underwent experimental conditions including 0% (i.e., normal airway), 50% and 75% stenosed. The primary outcome measure was phonation threshold flow (PTF), which is the rate of flow observed at the onset of phonation. For all larynges, the normal and stenosed conditions were sampled three times each and averaged. Analysis of the results revealed no statistically significant differences in PTF; however, descriptive data showed decreases in PTF and increased variability in PTF values as percent stenosis increased. These findings lay important groundwork for future research in SGS, specifically those that employ ex vivo methodologies. PTF has emerged as a promising means of quantifying voice function in addition to the traditional onset pressure measures. Future studies should examine a broader range of stenosis conditions with a larger sample size to promote generalization to clinical populations including individuals with SGS.

No description available.

No description available.