WIFIC — a program to assist in the production of CAMAC modules

A program — WIFIC — has been developed which assists in the production of CAMAC modules. Detailed point-to-point connection lists for a layered structure are produced with co-ordinates relative to individual integrated circuits or relative to the mounting medium. Optimized signal paths are obtained and positional conflicts are removed.     

Case studies in Gaussian process modelling of computer codes

In this paper we present a number of recent applications in which an emulator of a computer code is created using a Gaussian process model. Tools are then applied to the emulator to perform sensitivity analysis and uncertainty analysis. Sensitivity analysis is used both as an aid to model improvement and as a guide to how much the output uncertainty might be reduced by learning about specific inputs. Uncertainty analysis allows us to reflect output uncertainty due to unknown input parameters, when the finished code is used for prediction.The computer codes themselves are currently being developed within the UK Centre for Terrestrial Carbon Dynamics.     

An economic analysis of an automated system for interpreting electrocardiograms

For the past year routine electrocardiograms (ECGs) from the Heart Station at U.S. Naval Hospital, San Diego, California have been automatically interpreted using the Smith/Mayo computer program with an IBM 360/65 at the Naval Electronics Laboratory Center, San Diego, California. The ECGs are batch processed. In the near future, an on-line, automated ECG interpretation system will be centralized in the Heart Station and have the capability to process ECGs for all U.S. Navy medical facilities in Southern California. This paper discusses the economic implications of such a system and compares its costs with those of a manual system, the existing batch mode system and commercial ECG service bureaus for similar ECG workload volumes. Finally, an evaluation of the accuracy of the Smith/Mayo program's interpretation of 4,628 normal and abnormal ECGs is presented.     

AIRS radiance validation over ocean from sea surface temperature measurements

Demonstrates the accuracy of methods and in situ data for early validation of calibrated Earth scene radiances measured by the Atmospheric InfraRed Sounder (AIRS) on the Aqua spacecraft. We describe an approach for validation that relies on comparisons of AIRS radiances with drifting buoy measurements, ship radiometric observations and mapped sea surface temperature products during the first six months after launch. The focus of the validation is on AIRS channel radiances in narrow spectral window regions located between 800-1250 cm/sup -1/ and between 2500 and 2700 cm/sup -1/. Simulated AIRS brightness temperatures are compared to in situ and satellite-based observations of sea surface temperature colocated in time and space, to demonstrate accuracies that can be achieved in clear atmospheres. An error budget, derived from single channel, single footprint matchups, indicates AIRS can be validated to better than 1% in absolute radiance (equivalent to 0.5 K in brightness temperature, at 300 K and 938 cm/sup -1/) during early mission operations. The eventual goal is to validate instrument radiances close to the demonstrated prelaunch calibration accuracy of about 0.4% (equivalent to 0.2 K in brightness temperature, at 300 K and 938 cm/sup -1/).     

Dispersion of bound electron nonlinear refraction in solids

A two-hand model is used to calculate the scaling and spectrum of the nondegenerate nonlinear absorption. From this, the bound electronic nonlinear refractive index n₂ is obtained using a Kramers-Kronig transformation. The authors include the effects of two-photon and Raman transitions and the AC Stark shift (virtual band blocking). The theoretical calculation for n₂ shows excellent agreement with measured values for a five-order-of-magnitude variation in the modulus of n₂ in semiconductors and wide-gap optical solids. Beam distortion methods were used to measure n₂ in semiconductors. The observations result in a comprehensive theory that allows a prediction of n₂ at wavelengths beneath the band edge, given only the bandgap energy and the linear index of refraction. Some consequences for all-optical switching are discussed, and a wavelength criterion for the observation of switching is derived     

Solution of dynamic distributed parameter model of nondiabatic, fixed-bed reactor

Dynamic models of nondiabatic, fixed-bed reactors have several potential applications, many of which require these models to be both accurate and efficient to solve. In this paper, we present a new dynamic 1-D model, called the -model, that is an excellent approximation to the dynamic 2-D model. This new model provides significant savings in computational time with minimal sacrifice of physical detail. Two different spatial discretization techniques (orthogonal collocation on finite elements and biased-upwind differencing) are used to approximate the convection term in this 1-D model and both are found to yield acceptable results.     

The effects of ivermectin on onchocercal skin disease and severe itching: results of a multicentre trial

OBJECTIVE: To determine the effects of ivermectin in annual, 3-monthly and 6-monthly doses on onchocercal skin p6isease (OSD) and severe itching. METHOD: A multicentre, double-blind placebo controlled trial was conducted among 4072 residents of rural communities in Ghana, Nigeria and Uganda. Baseline clinical examination categorized reactive skin lesions as acute papular onchodermatitis, chronic papular onchodermatitis and lichenified onchodermatitis. Presence and severity of itching was determined by open-ended and probing questions. Clinical examination and interview took place at baseline and each of 5 subsequent 3-monthly follow-up visits. RESULTS: While prevalence and severity of reactive lesions decreased for all 4 arms, those receiving ivermectin maintained a greater decrease in prevalence and severity over time. The difference between ivermectin and placebo groups was significant for prevalence at 9 months and for severity at 3 months. Differences between placebo and ivermectin groups were much more pronounced for itching. From 6 months onward, the prevalence of severe itching was reduced by 40-50% among those receiving ivermectin compared to the trend in the placebo group. CONCLUSION: This is an important effect on disease burden as severe itching is for the affected people the most troubling complication of onchocerciasis. The difference among regimens was not significant, and the recommended regimen of annual treatment for the control of ocular onchocerciasis appears also the most appropriate for onchocerciasis control in areas where the skin manifestations predominate. The final determination of the effect on skin lesions requires a longer period of study.     

Conjugation in S. pombe: identification of a microtubule-organising centre, a requirement for microtubules and a role for Mad2

During the G1 phase of the cell cycle, cells of the fission yeast Schizosaccharomyces pombe can be induced to mate by nitrogen starvation and the presence of mating pheromones. Polarised growth towards cells of the opposite mating type (P or M) leads to the formation of a projection tip and, upon contact, localised cell wall degradation results in conjugation and cell fusion [1]. Here, we have investigated the role of microtubules in this process. We describe a previously unidentified microtubule-organising centre (MTOC) that forms at projection tips upon cell-to-cell contact, before cells fuse. Treatment of mating cells with the microtubule-destabilising drug thiabendazole (TBZ) showed that microtubule integrity was required for mating at two distinct stages: during projection tip formation and cell fusion. Projection tip formation requires filamentous (F) actin function [2] and microtubules are required for the localisation of F actin to the projection tip. We also identify a role during mating for Mad2--a mitotic checkpoint protein that is required in all eukaryotes to maintain the mitotic state in response to microtubule depolymerisation [3]. S. pombe mad2 mutant cells were compromised in their ability to mate upon removal of TBZ, indicating that in fission yeast, in the absence of microtubules, Mad2 is also required to maintain mating competence.     

Dextran modification of a Fab'--beta-lactamase conjugate modulated by variable pretreatment of Fab' with amine-blocking reagents

The physical and pharmacological properties of proteins can be altered by chemical modification with polymers. Preliminary studies showed that attachment of oxidized dextran to the bacterial protein, beta-lactamase (beta L) effectively reduced in vivo immunogenicity in mice with no loss of enzymatic activity. This report describes a general method for differentially dextran modifying the Fab' component of a Fab'--beta-lactamase conjugate by the use of amine-blocking reagents. Methyl acetimidate (MeAcm) and the N-succinimidyl derivative of (methylsulfonyl)ethyl carbonate (NHS-Msc), reagents which can reversibly block primary amines, were used in model studies to modulate the level of available reactive amines on the F(ab')2 fragments of both the anti-carcinoembryonic antigen antibody, ZCE025, and the antitumor-associated glycoprotein-72 antibody, CC49. MeAcm had little or no effect on immunoreactivity and was maximally effective in modulating dextran attachment, while NHS-Msc was much less effective. A comparison of NHS-Msc and MeAcm is described. Treatment of F(ab')2 with 5-300 mM MeAcm prior to dextran treatment showed a proportional decline in the level of dextran attachment as well as intramolecular cross-linking of the protein by the dextran polymers (6 kDa or 33-mer). A conjugate of beta L coupled to MeAcm-treated ZCE025 Fab' [reduced F(ab')2] was constructed under standard conditions using sulfosuccinimidyl N-[(4-carboxycyclohexyl)methyl]maleimide. After dextran modification, this conjugate maintained good immunoreactivity and enzymatic activity. Biodistribution studies in tumor-bearing nude mice of dextranated and nondextranated conjugate showed comparable overall distribution profiles except that the clearance of the dextranated conjugate from both blood and tumor was delayed about 48-72 h.