Book Review: Veterinary Ophthalmology

The second edition of this book, printed in less than two years after the first, contains more illustrations and some of the pictures have been redrawn. A few more photographic plates are included

Preservative Effects of Covering and Propionic Acid on Alfalfa Haylage in Bunker Silos

The preservation efficiency of covering alfalfa haylage with black plastic (polyethylene) and/or treating haylage with propionic acid was studied in two trials. Experiment 1 was designed to evaluate the influence of both covering and treatment with propionic acid on haylage chemical composition and heifer growth. In experiment 1, prop ionic acid was administered to the haylage at the chopper at 0.02% of the fresh forage weight. Chemical composition and ensiling temperature of the haylage were monitored and animal growth was measured with 16 Holstein heifers. Covered haylage was superior to treated haylage in quality as measured by chemical analyses and animal performance. Propionic acid lowered ensiling temperature to a lesser extent than covering. Experiment 2 was designed to compare a control alfalfa haylage (covered/untreated) to an uncovered haylage topically treated with 100% propionic acid. Ensiling temperature, chemical content, and animal performance of dairy heifers were evaluated. The control haylage had lower ensiling temperature and was superior in quality as measured by chemical analyses and heifer performance. Propionic acid addition was ineffective in lowering ensiling temperature and limiting extended fermentation. The data suggests that covering was more efficient than propionic acid addition in preserving alfalfa haylage in bunker silos

A Hybrid Optimal Control Approach to Maximum Endurance of Aircraft

Aircraft performance optimization is a field of increasing interest, especially with the prevalent use of flight management systems (FMS) on commercial aircraft, as well as the growing field of autonomous aircraft. This thesis addresses the maximum endurance performance mode. Maximizing the endurance of an aircraft has several applications in data collection, surveillance, and commercial flights. Each of these applications may be best suited for different aircraft such as fixed-wing or quad-rotor vehicles, with power plants being either fuel-burning or electric. The objectives of this thesis are to solve the maximum endurance problem using an optimal control framework for fixed-wing aircraft while developing a unified model of energy-depletion which encompasses both fuel-burning and all-electric aircraft. The unified energy-depletion model allows the results to be applied to turbojet, turbofan, turboprop, and all-electric aircraft. The problem of maximum endurance in cruise will be solved for a three-phase model of flight including climb, cruise, and descent. This problem is solved using a hybrid optimal control framework using a unified energy-depletion model. One of the advantages of using an optimal control framework is the possibility to develop analytical solutions. The results of this thesis include a general solution for maximizing the endurance of fixed-wing aircraft, as well as specific analytical solutions for each aircraft configuration wherever possible. Some benefits of analytical solutions are that they require the least amount of computation time and provide insight into the problem including sensitivities and physical dependencies. Simulations are provided to validate the results in the case of specific aircraft configurations (turbojet, turbofan, turboprop, and all-electric)

Factors affecting Removal of Bacterial Pathogens from Healthcare Surfaces during Dynamic Wiping

Wiping of surfaces contaminated with pathogenic bacteria is a key strategy for combatting transmission of healthcare associated infections. It is essential to understand the extent to which removal of bacteria is modulated by fibre properties, biocidal liquid impregnation and applied hand pressure. The influence of intrinsic and extrinsic factors on the removal efficiencies of pathogenic bacteria was studied. Nonwoven wipes made of either hydrophobic (polypropylene) or hygroscopic (lyocell) fibres were manufactured and dynamic removal efficiency of bacteria studied. The single most important parameter affecting bacterial removal efficiency was impregnation with biocidal liquid (p <0.05). For inherently hygroscopic 100% regenerated cellulose (lyocell) wipes impregnated with biocidal liquid, removal of E. coli, S. aureus and E. faecalis improved by increasing the fabric surface density and wiping pressure to their maximal values - 150 g.m-2 and 13.80 kN.m-2 respectively. For inherently hydrophobic 100% polypropylene nonwoven wipes, the same conditions maximised the removal efficiency of S. aureus, but for E. coli and E. faecalis a reduction in the wiping pressure to 4.68 kN.m-2 was required. Best practice involves the use of higher surface density wipes (150 g m-2) containing regenerated cellulose fibres loaded with liquid biocide, and applied with the greatest possible wiping pressure

Environmental contamination and hospital-acquired infection: factors that are easily overlooked.

There is an ongoing debate about the reasons for and factors contributing to healthcare-associated infection (HAI). Different solutions have been proposed over time to control the spread of HAI, with more focus on hand hygiene than on other aspects such as preventing the aerial dissemination of bacteria. Yet, it emerges that there is a need for a more pluralistic approach to infection control; one that reflects the complexity of the systems associated with HAI and involves multidisciplinary teams including hospital doctors, infection control nurses, microbiologists, architects, and engineers with expertise in building design and facilities management. This study reviews the knowledge base on the role that environmental contamination plays in the transmission of HAI, with the aim of raising awareness regarding infection control issues that are frequently overlooked. From the discussion presented in the study, it is clear that many unknowns persist regarding aerial dissemination of bacteria, and its control via cleaning and disinfection of the clinical environment. There is a paucity of good-quality epidemiological data, making it difficult for healthcare authorities to develop evidence-based policies. Consequently, there is a strong need for carefully designed studies to determine the impact of environmental contamination on the spread of HAI

Transmission of SARS and MERS coronaviruses and influenza virus in healthcare settings: the possible role of dry surface contamination

Viruses with pandemic potential including H1N1, H5N1, and H5N7 influenza viruses, and severe acute respiratory syndrome (SARS)/Middle East respiratory syndrome (MERS) coronaviruses (CoV) have emerged in recent years. SARS-CoV, MERS-CoV, and influenza virus can survive on surfaces for extended periods, sometimes up to months. Factors influencing the survival of these viruses on surfaces include: strain variation, titre, surface type, suspending medium, mode of deposition, temperature and relative humidity, and the method used to determine the viability of the virus. Environmental sampling has identified contamination in field-settings with SARS-CoV and influenza virus, although the frequent use of molecular detection methods may not necessarily represent the presence of viable virus. The importance of indirect contact transmission (involving contamination of inanimate surfaces) is uncertain compared with other transmission routes, principally direct contact transmission (independent of surface contamination), droplet, and airborne routes. However, influenza virus and SARS-CoV may be shed into the environment and be transferred from environmental surfaces to hands of patients and healthcare providers. Emerging data suggest that MERS-CoV also shares these properties. Once contaminated from the environment, hands can then initiate self-inoculation of mucous membranes of the nose, eyes or mouth. Mathematical and animal models, and intervention studies suggest that contact transmission is the most important route in some scenarios. Infection prevention and control implications include the need for hand hygiene and personal protective equipment to minimize self-contamination and to protect against inoculation of mucosal surfaces and the respiratory tract, and enhanced surface cleaning and disinfection in healthcare settings