A quantitative assessment of the amount of prion diverted to category 1 materials and wastewater during processing

In this article the development and parameterization of a quantitative assessment is described that estimates the amount of TSE infectivity that is present in a whole animal carcass (bovine spongiform encephalopathy [BSE] for cattle and classical/atypical scrapie for sheep and lambs) and the amounts that subsequently fall to the floor during processing at facilities that handle specified risk material (SRM). BSE in cattle was found to contain the most oral doses, with a mean of 9864 BO ID50s (310, 38840) in a whole carcass compared to a mean of 1851 OO ID50s (600, 4070) and 614 OO ID50s (155, 1509) for a sheep infected with classical and atypical scrapie, respectively. Lambs contained the least infectivity with a mean of 251 OO ID50s (83, 548) for classical scrapie and 1 OO ID50s (0.2, 2) for atypical scrapie. The highest amounts of infectivity falling to the floor and entering the drains from slaughtering a whole carcass at SRM facilities were found to be from cattle infected with BSE at rendering and large incineration facilities with 7.4 BO ID50s (0.1, 29), intermediate plants and small incinerators with a mean of 4.5 BO ID50s (0.1, 18), and collection centers, 3.6 BO ID50s (0.1, 14). The lowest amounts entering drains are from lambs infected with classical and atypical scrapie at intermediate plants and atypical scrapie at collection centers with a mean of 3 × 10−7 OO ID50s (2 × 10−8, 1 × 10−6) per carcass. The results of this model provide key inputs for the model in the companion paper published here

Friction in metal-on-metal total disc arthroplasty: effect of ball radius

Total Disc Arthroplasty (TDA) can be used to replace a degenerated intervertebral disc in the spine. There are different designs of prosthetic discs, but one of the most common is a ball-and-socket combination. Contact between the bearing surfaces can result in high frictional torque, which can then result in wear and implant loosening. This study was designed to determine the effects of ball radius on friction. Generic models of metal-on-metal TDA were manufactured with ball radii of 10, 12, 14 and 16 mm, with a radial clearance of 0.015 mm. A simulator was used to test each sample in flexion-extension, lateral bending and axial rotation at frequencies of 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75 and 2 Hz under loads of 50, 600, 1200 and 2000 N, in new born calf serum. Frictional torque was measured and Stribeck curves were plotted to illustrate the lubrication regime in each case. It was observed that implants with a smaller ball radius showed lower friction and showed boundary and mixed lubrication regimes, whereas implants with larger ball radius showed boundary lubrication only. This study suggests designing metal-on-metal TDAs with ball radius of 10 or 12 mm, in order to reduce wear and implant loosening

Performance and Thermoeconomic Analysis of a Biogas Engine Powered Ventilation System for Livestock Building

In this study, a biogas engine powered ventilation fan of a small swine farm was proposed. The research objective was to evaluate performance of, and apply a thermoeconomic analysis to an active ventilation system powered by a small biogas engine. Comparison was made against a gasoline engine and an electric motor. The engine used was a single-cylinder, four-stroke, spark ignited engine with capacity of 118 cm3. The biogas engine was found to be practically able to drive the ventilation fan with acceptable operation over a range of speeds and loads. At null price for biogas, the biogas engine proved to offer the lowest cost per product exergy unit at $0.054/MJ, which was considerably lower than the gasoline engine and electric motor

Training, efficiency and ergonomics in minimally invasive surgery

Knoopsgatchirurgie (laparoscopie) heeft een aantal bewezen voordelen voor de patiënt. Voor het operatieteam gaat er een aantal uitdagingen gemoeid met deze manier van opereren. Met name op het gebied van de ergonomie en de efficiëntie van het operatieproces en op het gebied van training van chirurgen die deze techniek willen toepassen zijn verbeteringen nodig. Hierover gaat dit proefschrift. In deel 1 van dit proefschrift onderzoeken we wat de beste houding is om laparoscopische chirurgie te kunnen uitvoeren. Met name de positie van de monitor is daarbij van belang. De monitor dient ruim onder ooghoogte, dicht bij het operatieveld en in lijn met de werkrichting van de chirurg geplaatst te worden. We tonen aan dat een speciaal voor laparoscopie ontworpen operatiekamer een significante verbetering van de ergonomie en een verbeterde efficiëntie tussen de operaties door kan opleveren. In deel 2 van dit proefschrift onderzoeken we een nieuwe manier van proceduretraining op de operatiekamer. Een cohort assistenten doorloopt een curriculum voor laparoscopische galblaasoperaties. Nadat zij hun basisvaardigheden hebben geleerd op een simulator begonnen ze met proceduretraining op de operatiekamer. Gedurende 6 operaties kregen ze tijdens elke ingreep herhaaldelijk korte video-instructies over de volgende stap die moest worden uitgevoerd. Na het zien van de instructie mochten ze die stap van de operatie uitvoeren. De beoordelingen van de assistenten die op deze manier zijn getraind verbeterden sneller dan in een controle groep. We tonen aan dat deze methode effectief en uniform is terwijl de efficiëntie van het operatieproces niet benadeeld wordt

PEEK (Polyether-ether-ketone) Based Cervical Total Disc Arthroplasty: Contact Stress and Lubrication Analysis

This paper presents a theoretical analysis of the maximum contact stress and the lubrication regimes for PEEK (Polyether-ether-ketone) based self-mating cervical total disc arthroplasty. The NuNec® cervical disc arthroplasty system was chosen as the study object, which was then analytically modelled as a ball on socket joint. A non-adhesion Hertzian contact model and elastohydrodynamic lubrication theory were used to predict the maximum contact stress and the minimum film thickness, respectively. The peak contact stress and the minimum film thickness between the bearing surfaces were then determined, as the radial clearance or lubricant was varied. The obtained results show that under 150 N loading, the peak contact stress was in the range 5.9 – 32.1 MPa, well below the yield and fatigue strength of PEEK; the calculated minimum film thickness ranged from 0 to 0.042 µm and the corresponding lambda ratio range was from 0 to 0.052. This indicates that the PEEK based cervical disc arthroplasty will operate under a boundary lubrication regime, within the natural angular velocity range of the cervical spine

A Review of the Design Process for Implantable Orthopedic Medical Devices

The design process for medical devices is highly regulated to ensure the safety of patients. This paper will present a review of the design process for implantable orthopedic medical devices. It will cover the main stages of feasibility, design reviews, design, design verification, manufacture, design validation, design transfer and design changes

Warrior Knowledge

In the fall semester of 2008 Lieutenant Colonel Angle, Air Force ROTC Commander of Detachment 800 at the University of Tennessee, asked if a cadet within the detachment would write a history of the University of Tennessee. Included should be a military history of East Tennessee and the long tradition of military education at this university. Up to this point there was no document available for cadets to have an understanding of their institution’s past. I was selected to lead this project. Not from Tennessee and without knowledge of the university, the journey into the past was a rewarding experience. The following history begins with the University of Tennessee, founded before there was a state of the same name. You will walk through a past of continual physical and educational change. After you will journey through the rich military history of this area and come across names of Tennesseans who have volunteered for their nation. Some of these men are John Sevier, Sam Houston, Lawrence Tyson, Alvin York, and Bruce Holloway. Then you will step back in time and trace the development of military instruction and ROTC at the University of Tennessee. Knowledge is an important key to success, and the final portion of this document covers Detachment 800 Warrior Knowledge. Hopefully the words that follow will bring the same sense of pride in you that it did me as a Tennessee Volunteer and future officer in the United States Air Force