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This report identifies and discusses the management issues and resources associated with establishing a microcomputer support center within an organization. A general introduction supplies a definition of a microcomputer support center and a historical perspective on data processing services. The remainder of the document is divided into two major sections--Starting the Center and Operating the Center. Topics addressed include: (1) funding the center; (2) establishing center objectives; (3) need for a clear definition of center responsibilities; (4) options for placement of a center within the organization; (5) level of center staffing; (6) necessary staff skills; (7) sources for staff; (8) center facilities, including space, equipment, and software; (9) suggested center services; (10) hints for maintaining qualified staff, equipment, and software; (11) suggested areas to be covered in policy statements; and (12) evaluation methods for assessing the center operations and its staff. Concluding remarks on the role of the microcomputer support center in managing end user computing, a list of 41 references, and 21 sources for additional information complete the report. (JB)

This manual is intended to provide guidance to those interested in establishing an electronic bulletin board system (BBS) that enables users to send and read messages both individually and by teleconferencing, and to transfer files to and from the system. The manual begins with a definition of a BBS and explains its uses and facilities. It then gives instructions for starting and operating a BBS, including: (1) hardware requirements (microcomputers, modems, telephone lines, printer and a tape backup system); (2) software requirements (bulletin board system software, call analyzer software, and multi-tasking software); and (3) the selection of a system operator. Also discussed are the day-to-day operations of a BBS, including monitoring messages, refreshing bulletins or files, taking security precautions to safeguard the system, and analyzing bulletin board traffic. The appendices include a list of the functional features of a BBS, examples of the screen displays from the Microcomputer Electronic Information Exchange (MEIE) BBS, and an explanation of XMODEM file transfer procedures. It is noted that the MEIE is in the public domain and representative of similar commercially available products. (8 references) (DB)

Benthic ecosystems have come under intense pressure, due to eutrophication-driven oxygen decline and industrial metal contamination. One of the most toxic metals is Cadmium (Cd), which is lethal to many aquatic organisms already at low concentrations. Denitrification by facultative anaerobic microorganisms is an essential process to transform, but also to remove, excess nitrate in eutrophied systems. Cd has been shown to decrease denitrification and sequester free sulfide, which is available when oxygen is scarce and generally inhibits complete denitrification (i.e. N2O to N2). In polluted sediments, an interaction between oxygen and Cd may influence denitrification and this relationship has not been studied. For example, in the Baltic Sea some sediments are double exposed to both Cd and hypoxia. In this study, we examined how the double exposure of Cd and fluctuations in oxygen affects denitrification in Baltic Sea sediment. Results show that oxygen largely regulated N2O and N2 production after 21 days of exposure to Cd (ranging from 0 to 500 μg/L, 5 different treatments, measured by the isotope pairing technique (IPT)). In the high Cd treatment (500 μg/L) the variation in N2 production increased compared to the other treatments. Increases in N2 production are suggested to be an effect of 1) enhanced nitrification that increases NO3 − availability thus stimulating denitrification, and 2) Cd successfully sequestrating sulfide (yielding CdS), which allows for full denitrification to N2. The in situ field sediment contained initially high Cd concentrations in the pore water (∼10 μg/L) and microbial communities might already have been adapted to metal stress, making the effect of low Cd levels negligible. Here we show that high levels of cadmium pollution might increase N2 production and influence nitrogen cycling in marine sediments. © 2019 The Authors

Lettuce grown in soil is found to contain high concentrations of arsenic (As). This paper investigates the uptake and speciation of As in lettuce as well as the influence of silicon (Si) on As uptake, since Si may decrease it. Lettuce plants were cultivated in nutrient solution containing arsenite or arsenate with or without silicate. The uptake and distribution of As between roots and shoots, As accu-mulation in cell walls, As speciation, and toxic effects on growth were analysed. Results indicate that arsenite was more toxic to lettuce than was arsenate. Silicate decreased arsenate toxicity but had little effect on arsenite toxicity. In contrast, Si decreased arsenite uptake more than arsenate uptake. The concentration of arsenate was higher than that of arsenite in the plants independent of the As species added. When arsenate was added, the As concentration in shoots was half of that in the roots and this distribution did not change with Si addition. When arsenite was added, approximately 10% of As was found in the shoots and 90% in the roots; this pattern changed in the presence of Si, and As became evenly distributed in the plant. In both roots and shoots, approximately 40% of the As was found in the cell wall fraction; when arsenite was added, the presence of Si increased this fraction to 47%, but only in the shoots. The extraction efficiency when analysing the As species was lower in shoots than in roots, especially in the presence of arsenite and Si. The opposite was found for As concentration in pellets after extraction. This indicated variation in the binding strength of arsenite and arsenate between roots and shoots and between Si-and non-Si-treated plants., QC 20160208

Danish cancer patients generally have a poorer survival than Swedish cancer patients. The difference is most pronounced for certain tumour types, e.g. common types such as lung, breast, colorectal, and prostate cancer. The reasons are not clear. The present article examines if differences in the diagnostic workup and treatment can explain some of this variation.

As part of the treatment prescription procedure, one has to prescribe in anatomical terms any GTV (Gross Tumor Volume) according to the general TNM-rules as well as any other tissues that are to be treated for presumed subclinical diseases. These prescriptions of one or several Clinical Target Volumes (CTVs) are based on general oncological principles, and are not related to the treatment modality. If external beam radiotherapy is being used, one has to consider special problems related to different geometric inaccuracies and uncertainties, which can be both intrafractional and interfractional. Such inaccuracies and uncertainties are due to either the position, shape and size of the patient/tissues in relation to a fix point, or to variations in beam geometry. The two different types of variations may or may not co-variate. A margin or margins for these uncertainties has to be included in the dose planning procedure, which then will evaluate a static situation, representing the CTV(s) plus geometric ``safety`` margin(s) (Planning Target Volume, PTV) and in fact not the true clinical situation. The dose distribution arrived at for this static representation will however have to be considered as representative for the CTV. This presents of course a dilemma, but one has to accept a reasonable compromise. There is no general rule on the size of the different geometric uncertainties or how they should be added up. Individual evaluations are needed.

The International Commission on Radiation Units and Measurements (ICRU) has published the Report 50 ''Prescribing, Recording and Reporting Photon Beam Therapy'' (1993). The aim of the Report is to promote the use of a common set of definitions and concepts for specifying and reporting the doses in radiation therapy, as well as the volumes in which they are prescribed and delivered. Different volumes need to be identified prior to treatment planning: the gross tumour volume (GTV) and the clinical target volume (CTV). The planning target volume (PTV) is defined for treatment planning. The treated volume and the irradiated volume are identified when the treatment techniques and irradiation plan have been decided upon. As a general recommendation, the dose at, or near, the centre of the PTV, as well as the maximum and the minimum dose, shall be reported. Additional information when clinically relevant and available, should also be reported. The system of recommendations for reporting dose is based on the selection of a point within the PTV, which is referred to as the ICRU Reference Point. The ICRU Reference Point is selected firstly at the centre, or in the central part, of the PTV, and secondly on, or near, the central axes of the beams. A certain degree of inhomogeneity of the absorbed dose throughout the PTV cannot be avoided. Therefore, as a basic requirement, the best estimate of the maximum dose and the minimum dose to the PTV shall be reported together with the dose at the ICRU Reference Point. These 3 dose values then indicate the dose profile within the PTV. ICRU Report 50 allows for reporting basic data for all treatments at any level of complexity for absorbed dose computation. It also allows for reporting additional clinical and relevant data obtained by sophisticated methods. The recommendations are thus applicable to all external radiotherapy procedures.

A quality assurance programme in brachytherapy implies a general consensus on the method of dose and volume specification for reporting. This in turn implies a consensus on certain definitions of terms and concepts. For several decades, the ICRU (International Commission on Radiation Units and Measurements) has been actively involved in an effort to reach a consensus between different brachytherapy centres worldwide, and to improve uniformity in reporting. The ICRU has prepared two reports containing recommendations for reporting brachytherapy treatments. The first, report #38 published in 1985, deals with intracavitary therapy in gynecology. The second deals with interstitial therapy, and is now in press. A summary of these two ICRU reports is presented here. Some definitions of terms and concepts are first recalled and discussed: Total Reference Air Kerma (TRAK), gross tumor volume (GTV), clinical target volume (CTV), treated volume, mean central dose, dose uniformity parameters, etc. Specific recommendations for reporting interstitial and intracavitary brachytherapy are then presented.