Chemical analysis of veterinary drugs in food. 1. General methods and gas chromatographic procedures

A review is presented that in the first section describes current techniques for preparation, extraction and clean up of food samples for the determination of veterinary drug residues by chemical methods. The second section gives an overview of gas chromatographic methods published up to 1983 for the analysis of meat, liver, kidney, egg and milk for residues of antibiotics and chemotherapeutic agents. Discussed are stability of the compounds, derivatization, detection and particular aspects of their metabolism. The structural formula is given for all drugs mentioned. The procedures for determination are summarized in a table, together with the most important analytical parameters.     

Traversing step obstacles with manual wheelchairs

In the public transport system, there are sometimes step obstacles, such as curbs, steps, entrance steps of vehicles, edges of lifting platforms, internal steps in vehicles, etc. This paper describes research work carried out in Sweden to specify the heights of step obstacles possible to traverse with a manual wheelchair manoeuvred by an attendant. The work included trials with the subjects manoeuvring two different kinds of wheelchairs, with dummies as occupants, over a step obstacle with adjustable height. It also included trials with a person in the wheelchair. The subjects were 20 healthy persons in the age range of 23-60 years, with no or only little experience of manoeuvring wheelchairs, chosen to represent bus drivers or other helpers. They rated their perceived feeling of effort on a 10-level rating scale with ratio properties. The occupant rated the feeling of comfort and safety in three grades. All trials were recorded using a video-camera. From the video-film, the situations and series of actions of the subjects were analysed and the length of time for each task was measured. The forces needed when traversing step obstacles with a wheelchair were calculated according to the principles of mechanics and processed by a computer for the different principal traversing situations. The results show that for the planning of systems for public transportation, where the passenger can get assistance, a step height of 50 mm is acceptable, and a step height of 100 mm can be acceptable if there is enough room to manoeuvre the wheelchair, so that it is possible to choose the most convenient way to traverse the step. Higher heights should be avoided.     

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Book reviews

     

Inflammatory aneurysm of the ascending aorta and aortic arch

Transbronchial needle aspiration (TBNA) is a valuable, minimally invasive procedure for diagnosing and staging lung cancer in patients, but it is underutilized by practicing pulmonologists. To assess the approach to TBNA of current pulmonary Fellows, we recorded their computerized interactive responses during the 1995 American College of Chest Physicians Fellows' Conference. Among 109 Fellows attending, only 10% reported that they routinely (> or = 85% of cases) performed TBNA to diagnose or stage malignant disease, and 40% noted that they rarely (< or = 5% of cases) performed it. They estimated their diagnostic TBNA yields in patients with mediastinal cancer as follows: > or = 80% by 2% of Fellows; between 25% and 80% by 54% of Fellows; and < 25% by 45% of Fellows. They noted that the main limitations of TBNA at their institutions were suboptimal bronchoscopy technique (30%), technician support (1%), cytopathology support (14%), all of these factors (25%), or the belief that TBNA is not useful (30%). TBNA is currently underutilized and/or underemphasized at bronchoscopy training programs. Major modifications of Fellow experiences are necessary if TBNA is to impact optimally on patient management.     

Entropies of general quantum states

The entropy and the mutual entropy for states and channels are totally studied in general quantum systems described byC*-algebras. In particular, we discuss the relations among theS-entropy and the mutual entropy introduced by Ohya and the Connes-Narnhofer-Thirring entropy.