A 30-b integrated logarithmic number system processor

The authors describe an integrated processor that performs addition and subtraction of 30-b numbers in the logarithmic number system (LNS). This processor offers 5-MOPS performance in 3-μm CMOS technology, and is implemented in a two-chip set comprising 170 K transistors. Two techniques are used to achieve this precision in a moderate circuit area. Linear approximation of the LNS arithmetic functions using logarithmic arithmetic is shown to be simple due to the particular functions involved. A segmented approach to linear approximation minimizes the amount of table space required. Subsequent nonlinear compression of each lookup table leads to a further reduction in table size. The result is that a factor of 285 reduction in table size is achieved, compared to previous techniques. The circuit area of the implementation is minimized by optimizing the table parameters, using a computer program that accurately models ROM area. The implementation is highly pipelined, and produces one result per clock cycle using a ten-stage pipeline     

Stability of rack structures

Standard commercial pallet racking is used in warehouses, factories, shops and a multitude of other places where palletised goods are to be stored. The structural analysis of this type of structure is complicated by the semi-rigid nature of the beam-to-upright connection, which is different from one manufacturer to another.In the present paper an attempt has been made to provide a simple design approach to the stability of pallet rack structures, and the effect that the form of the moment-rotation characteristic has on the type of stability demonstrated by the system.Finally the role of small imperfections is studied, and the effect that they have on the maximum load carrying capacity of the structure is shown.     

Using fractal structure to describe nickel crystal morphology

The morphology of nickel crystals can be quantified using measurements of fractal structure. In the study described in this article, fractal dimensions of cross sections of 16 nickel samples were determined, and the numerical analysis indicates that the more rugged surfaces are characterized by higher fractal dimensions although the relationship between morphology and fractal dimension is relatively weak. However, the data also show that fractal dimension is a better predictor of morphology than apparent density, which is the measurement currently used. The nickel samples were also subjected to an avalanching disc technique that has the potential to separate out the differences in flow in the different types of nickel powder. The differences in flow between powders were ascribed to the similar gross morphologies of the particles, and the presence of shattered individual particles in the mix. For more information, contact A.E. Lewis, University of Cape Town, Precipitation and Crystallisation Research Facility, Department of Chemical Engineering, Rondebosch, 7701, South Africa; +27-21-650-4091; fax +27-21-689-7479; e-mail alison@chemeng.uct.ac.za.     

Performance Metrics for Information Security Risk Management

Qualitative methods are available for risk management, but better practice would use quantitative risk management based on expected losses and related metrics. Measuring the success of information security investments is best accomplished by measuring reductions in expected loss.     

Mapping the Characteristics of a 'Good' Play Therapist.

In this pilot study, concept mapping, a methodological approach combining qualitative and quantitative analytic strategies, was used to identify the therapist qualities, competencies, and skills necessary for effective play therapy outcomes as perceived by a sub-sample of 28 experienced play therapists who are members of the Association for Play Therapy (APT). The clusters associated with the therapeutic relationship and facilitative skills (e.g., empathy, warmth, and genuineness) were rated as the most essential skills to possess and also as the most difficult to develop. In contrast, the clusters associated with play therapy interventions and theories were rated as the least important skills to possess but as the easiest to acquire. The findings are discussed, with implications for therapeutic practice, research, and policy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Solar building—European Union Research and Development Programmes

The European Commission's (EC) energy R&D programmes have completed two decades of progress. In the building sector special attention has been given to technology transfer and research dissemination, because of the particular problems which arise given the characteristics of the European construction industry, its diversity and fractured structure, and rather conservative nature.Projects such as the earlier Project MONITOR and BUILDING 2000, and the more recent INNOBUILD and SOLINFO projects and the Solar House programme together represent an unusual, if not unparalleled, effort aimed at bringing about technical change in building design and providing the necessary design and evaluation support and tools to professional architects and students and, to a lesser extent, to engineers. These projects are complemented by (and draw heavily from) an ambitious but clearly-targeted series of research projects investigating major energy-related issues concerning the heating, cooling and daylighting of buildings and deficiencies in knowledge of climate and human comfort, and building performance; activities such as the construction of passive solar test centres in ten EU Member States, each typically with four identical test cells equipped with interchangeable south walls, identical heating and cooling systems, sensors, and data acquisition systems. There is now in Europe considerable emphasis on the challenges of building in warmer climates, and on advancing daylighting design and performance and developing new materials.     

Effect of prenatal alcohol and cigarette exposure on two- and six-month-old infants'' adrenocortical reactivity to stress

Biologic data on benzene metabolite doses, cytotoxicity, and genotoxicity often show that these effects do not vary directly with cumulative benzene exposure (i.e., concentration times time, or c x t). To examine the effect of an alternate exposure metric, we analyzed cell-type specific leukemia mortality in Pliofilm workers. The work history of each Pliofilm worker was used to define each worker's maximally exposed job/department combination over time and the associated long-term average concentration associated with the maximally exposed job (LTA-MEJ). Using this measure, in conjunction with four job exposure estimates, we calculated SMRs for groups of workers with increasing LTA-MEJs. The analyses suggest that a critical concentration of benzene exposure must be reached in order for the risk of leukemia or, more specifically, AMML to be expressed. The minimum concentration is between 20 and 60 ppm depending on the exposure estimate and endpoint (all leukemias or AMMLs only). We believe these analyses are a useful adjunct to previous analyses of the Pliofilm data. They suggests that (a) AMML risk is shown only above a critical concentration of benzene exposure, measured as a long-term average and experienced for years, (b) the critical concentration is between 50 and 60 ppm when using a median exposure estimate derived from three previous exposure assessments, and is between 20 and 25 ppm using the lowest exposure estimates, and (c) risks for total leukemia are driven by risks for AMML, suggesting that AMML is the cell type related to benzene exposure.     

Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version (K-SADS-PL): initial reliability and validity data

OBJECTIVE: To describe the psychometric properties of the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime version (K-SADS-PL) interview, which surveys additional disorders not assessed in prior K-SADS, contains improved probes and anchor points, includes diagnosis-specific impairment ratings, generates DSM-III-R and DSM-IV diagnoses, and divides symptoms surveyed into a screening interview and five diagnostic supplements. METHOD: Subjects were 55 psychiatric outpatients and 11 normal controls (aged 7 through 17 years). Both parents and children were used as informants. Concurrent validity of the screen criteria and the K-SADS-PL diagnoses was assessed against standard self-report scales. Interrater (n = 15) and test-retest (n = 20) reliability data were also collected (mean retest interval: 18 days; range: 2 to 36 days). RESULTS: Rating scale data support the concurrent validity of screens and K-SADS-PL diagnoses. Interrater agreement in scoring screens and diagnoses was high (range: 93% to 100%). Test-retest reliability kappa coefficients were in the excellent range for present and/or lifetime diagnoses of major depression, any bipolar, generalized anxiety, conduct, and oppositional defiant disorder (.77 to 1.00) and in the good range for present diagnoses of posttraumatic stress disorder and attention-deficit hyperactivity disorder (.63 to .67). CONCLUSION: Results suggest the K-SADS-PL generates reliable and valid child psychiatric diagnoses.