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Closed terrain depressions are geomorphic features that show scale invariance over the wide range of scales on which they occur, from metres to thousands of kilometres. They are also global features that are present on all continents. Morphometric analyses of these depressions are now possible because of the availability of global digital elevation models and advances in methods for mapping closed depressions. Here, a simple and automatic but efficient method is proposed for mapping closed terrain depressions. The GTOPO30 global digital elevation model, with a spatial resolution of around 1 km, was used to map the closed depressions of eight large test sites sampled from all inhabited continents. The identified and delineated terrain depressions include lake watersheds together with many other terrain depressions including deserts, karst terrains and rift valleys. A fractal analysis shows that South America and Central Africa have similar, and also the largest, fractal dimensions; Central Europe and North Africa have intermediate fractal dimensions; and North America, Central Asia, the Near East and Australia have similar, low fractal dimensions. The methodology proposed in this paper can be used to identify areas of interest for which a more exhaustive analysis, using digital elevation models with better spatial resolution, can be conducted. [ABSTRACT FROM AUTHOR]

This paper describes a proposed method for clustering attributes on the basis of their spatial variability and the uncertainty of cluster membership. The method is applied to geometallurgical domaining in mining applications. The main objective of geometallurgical clustering is to ensure consistent feed to a processing plant by minimising transitions between different types of feed coming from different domains (clusters). For this purpose, clusters should contain not only similar geometallurgical characteristics but also be located in as few contiguous and compact spatial locations as possible so as to maximise the homogeneity of ore delivered to the plant. Most existing clustering methods applied to geometallurgy have two problems. Firstly, they are unable to differentiate subsets of attributes at the cluster level and therefore cluster membership can only be assigned on the basis of exactly identical attributes, which may not be the case in practice. Secondly, as they do not take account of the spatial relationships they can produce clusters which may be spatially dispersed and/or overlapped. In the work described in this paper a new clustering method is introduced that integrates three distinct steps to ensure quality clustering. In the first step, fuzzy membership information is used to minimise compactness and maximise separation. In the second step, the best subsets of attributes are defined and applied for domaining purposes. These two steps are iterated to convergence. In the final step a graph-based labelling method, which takes spatial constraints into account, is used to produce the final clusters. Three examples are presented to illustrate the application of the proposed method. These examples demonstrate that the proposed method can reveal useful relationships among geometallurgical attributes within a clear and compact spatial structure. The resulting clusters can be used directly in mine planning to optimise the ore feed to be delivered to the processing plant. [ABSTRACT FROM AUTHOR]

The incorporation of the uncertainties of geometallurgical variables in mine planning provides new opportunities for decision-makers to analyse, compare and choose among many scenarios to achieve an optimal balance between economic and operational objectives. This research focuses on maximising economic return and minimising the risk arising from the uncertainty associated with geometallurgical variables. We formulate two-objective optimisation problems based on an underground mining operation. The first objective is the maximisation of the Net Smelter Return, which includes penalties associated with deleterious elements in concentrates. Four different objectives were tested as candidates for the second objective: Volatility, Value at Risk, Conditional Value at Risk and deviation from the planned production target. The first three are measures of economic risk and the fourth is a measure of operational risk. Uncertainties in metal grades, geometallurgical recoveries and grades in concentrate are included in the proposed model. Our results demonstrate that geometallurgical uncertainties can be successfully integrated into production scheduling optimisation in a multi-objective approach and the problem can be solved using genetic algorithms to yield useful conclusions to support the decision-making process. [ABSTRACT FROM AUTHOR]

The integration of geological and geometallurgical data can significantly improve decision-making and optimize mining production due to a better understanding of the resources and their metallurgical performances. The primary-response rock property framework is an approach to the modelling of geometallurgy in which quantitative and qualitative primary properties are used as proxies of metallurgical responses. Within this framework, primary variables are used to fit regression models to predict metallurgical responses. Whilst primary rock property data are relatively abundant, metallurgical response property data are not, which makes it difficult to establish predictive response relationships. Relationships between primary input variables and geometallurgical responses are, in general, complex, and the response variables are often non-additive which further complicates the prediction process. Consequently, in many cases, the traditional multivariate linear regression models (MLR) of primary-response relationships perform poorly and a better alternative is required for prediction. Projection pursuit is a powerful exploratory statistical modelling technique in which data from a number of variables are projected onto a set of directions that optimize the fit of the model. The purpose of the projection is to reveal underlying relationships. Projection pursuit regression (PPR) fits standard regression models to the projected data vectors. In this paper, PPR is applied to the modelling of geometallurgical response variables. A case study with six geometallurgical variables is used to demonstrate the modelling approach. The results from the proposed PPR models show a significant improvement over those from MLR models. In addition, the models were bootstrapped to generate distributions of feasible scenarios for the response variables. Our results show that PPR is a robust technique for modelling geometallurgical response variables and for assessing the uncertainty associated with these variables. [ABSTRACT FROM AUTHOR]

The authors provide their assessment of current challenges in strategic mine planning and some approaches for addressing them. Challenges covered are quantification of downstream processes and their integration into orebody models; spatial characterisation of geometallurgical variables and their integration into block models, scheduling and mine optimisation; spatial characterisation of new variables for new types of mining; flexibility in planning and design to manage risk and minimise its impact; IT infrastructure for rapid on-line data collection and processing. Most of these challenges require new types of data, variables, modelling and estimation methods. Foremost among new variable types are geometallurgical and dynamic rock mass characterisation variables. New types of data and data collection include rapid generation of very large amounts of on-line sensor data and the consequent need for rapid processing and modelling of these data. The paper includes examples of models and outputs to illustrate approaches and potential solutions. [ABSTRACT FROM AUTHOR]

Fracture network modelling plays an important role in many application areas in which the behaviour of a rock mass is of interest. These areas include mining, civil, petroleum, water and environmental engineering and geothermal systems modelling. The aim is to model the fractured rock to assess fluid flow or the stability of rock blocks. One important step in fracture network modelling is to estimate the number of fractures and the properties of individual fractures such as their size and orientation. Due to the lack of data and the complexity of the problem, there are significant uncertainties associated with fracture network modelling in practice. Our primary interest is the modelling of fracture networks in geothermal systems and, in this paper, we propose a general stochastic approach to fracture network modelling for this application. We focus on using the seismic point cloud detected during the fracture stimulation of a hot dry rock reservoir to create an enhanced geothermal system; these seismic points are the conditioning data in the modelling process. The seismic points can be used to estimate the geographical extent of the reservoir, the amount of fracturing and the detailed geometries of fractures within the reservoir. The objective is to determine a fracture model from the conditioning data by minimizing the sum of the distances of the points from the fitted fracture model. Fractures are represented as line segments connecting two points in two-dimensional applications or as ellipses in three-dimensional (3D) cases. The novelty of our model is twofold: (1) it comprises a comprehensive fracture modification scheme based on simulated annealing and (2) it introduces new spatial approaches, a goodness-of-fit measure for the fitted fracture model, a measure for fracture similarity and a clustering technique for proposing a locally optimal solution for fracture parameters. We use a simulated dataset to demonstrate the application of the proposed approach followed by a real 3D case study of the Habanero reservoir in the Cooper Basin, Australia. [ABSTRACT FROM AUTHOR]

The characterisation of rock fracture networks is an important component of rock engineering applications involving stability assessment or fluid flow analysis. However, the derivation of a reliable rock fracture model remains a very challenging problem in practice. This paper describes a Bayesian framework, in the form of Markov Chain Monte Carlo (MCMC) simulation, for the construction of such a model. Model conditioning using different data sources is discussed including seismic events recorded during hydraulic fracture stimulation, rock face fracture mapping data and downhole geophysical survey data. The freeware FracSim3D is used for the simulations. [ABSTRACT FROM AUTHOR]

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This paper deals with the problem of reconstructing a significantly under-sampled signal of interest (primary signal) using the few data available for that signal and an exhaustively sampled secondary signal. This is a typical situation in various geophysical settings, as for example in core-log integration. Core measurements are made in the laboratory and are very precise but, because core recovery may be fragmentary along the borehole, there are large gaps in the information these measurements provide. On the other hand, wireline logging offers a complete set of measurements along the borehole. The variable of interest (e.g. porosity) can be measured directly in the cores (i.e. primary variable) while the logging variables are proxy variables (e.g. neutron porosity, electrical resistivity, sonic velocity). The optimal combination of both types of measurements can improve the assessment of the variable of interest. Geostatistics offers a methodology for merging such different types of information. Assuming a linear relation between the primary and secondary variables, various geostatistical techniques are applicable: simple kriging with an estimated local mean, kriging with an external drift, cokriging and Bayesian integration. These methods are compared in a simulation experiment in which the signal is considered to be discrete with 1024 data values and reconstruction is assessed for the case when 10% of the data are known (i.e. 102 data values) and for the case when 50% of the signal is known (512 data values). The various methods are assessed using statistics of the real error involved in the reconstruction and the ratio between the real error and the estimated error. The methods are ranked according to the values of these statistics and their inference and computational requirements. The methodology is demonstrated on a case study in which a few tens of core samples of effective porosity are integrated with a much more exhaustive set of wireline neutron porosity. [ABSTRACT FROM AUTHOR]

This paper reviews the use of the cracked Chevron-notched Brazilian disc (CCNBD) for fracture toughness testing. Theoretical and experimental backgrounds of the method are described. Some issues regarding the current development (i.e., recalibration) of the specimen geometry are presented and discussed. A number of geometries related to the CCNBD proposed recently for fracture toughness testing of rock are then introduced and commented on. [ABSTRACT FROM AUTHOR]

Increasing global competition, quality standards, environmental awareness and decreasing ore prices impose new challenges to mineral industries. Therefore, the extraction of mineral resources requires careful design and scheduling. In this research, simulated annealing (SA) is recommended to solve a mine production scheduling problem. First of all, in situ mineral characteristics of a deposit are simulated by sequential Gaussian simulation, and averaging the simulated characteristics within specified block volumes creates a three-dimensional block model. This model is used to determine optimal pit limits. A linear programming (LP) scheme is used to identify all blocks that can be included in the blend without violating the content requirements. The Lerchs-Grosmann algorithm using the blocks identified by the LP program determines optimal pit limits. All blocks that lie outside of the optimal pit limit are removed from the system and the blocks within the optimal pit are submitted to the production scheduling algorithm. Production scheduling optimization is carried out in two stages: Lagrangean parameterization, resulting in an initial sub-optimal solution, and multi-objective SA, improving the sub-optimal schedule further. The approach is demonstrated on a Western Australian iron ore body. [ABSTRACT FROM AUTHOR]

Summary Background Vulval vestibulitis is a condition characterized by the sudden onset of a painful burning sensation, hyperalgesia, mechanical allodynia, and occasionally pruritus, localized to the region of the vulval vestibulus. It is considered the commonest subset of vulvodynia. Pain precipitated in the absence of nociceptor stimuli might be triggered by previous peripheral nerve injury, or by the release of neuronal mediators, which set off inappropriate impulses in nonmyelinated pain fibres sensitizing the dorsal horn neurones. The pathophysiology of vulval vestibulitis is still unclear. Objectives The objective of this study was to evaluate the nerve fibre density and pattern, in specimens of vulval vestibulus, in normal subjects and in patients with vestibulitis, and provide objective diagnostic criteria for this condition. Methods Twelve patients with a history of the vestibulitis type of vulvodynia, and eight normal subjects underwent biopsy of the posterior wall of the vulval vestibule. Quantitative immunohistochemistry was performed, using antisera to the general neuronal marker protein gene product (PGP) 9·5, and to the neuropeptide calcitonin gene-related peptide (CGRP), on 15-µm sections. Results There was a statistically significant increase of density and number of PGP 9·5 immunoreactive in the papillary dermis of patients with vulvodynia of the vestibulitis type, compared with those of controls. However, the distribution pattern of the innervation showed no significant change. There were no significant differences in CGRP staining between patients and controls. Conclusions It is concluded that the increase of PGP 9·5 immunoreactive nerve fibres, in patients with vulvodynia, may be either secondary to nerve sprouting, or may represent neural hyperplasia. Increased innervation may be applied as an objective diagnostic finding in vulval vestibulitis syndrome. [ABSTRACT FROM AUTHOR]

A growing area of application for geostatistical conditional simulation is as a tool for risk analysis in mineral resource and environmental projects. In these applications accurate field measurement of a variable at a specific location is difficult and measurement of variables at all locations is impossible. Conditional simulation provides a means of generating stochastic realizations of spatial (essentially geological and/or geotechnical) variables at unsampled locations thereby quantifying the uncertainty associated with limited sampling and providing stochastic models for 'downstream' applications such as risk assessment. However, because the number of experimental data in practical applications is limited, the estimated geostatistical parameters used in the simulation are themselves uncertain. The inference of these parameters by maximum likelihood provides a means of assessing this estimation uncertainty which, in turn, can be included in the conditional simulation procedure. A case study based on transmissivity data is presented to show the methodology whereby both model selection and parameter inference are solved by maximum likelihood. The authors give an overview of their previously published work on maximum likelihood estimation of geostatistical parameters with particular reference to uncertainty analysis and its incorporation into geostatistical simulation. [ABSTRACT FROM AUTHOR]

In a small-plot field study, malathion formulated in pregelatinized corn flour as granules at 0.1% was hand applied at a rate of 11.1 kg/ha of granules (0.01l kg [AI]/ha) of granules in 1992 and 1993. Control of Carpophilus lugubris Murray and Helicocerpa zea (Boddie) with a single treatment of the granules was generally equivalent to that seen when a commercial formulation of malathion was applied in 5 sprays at a rate of 1.1 kg (AI)/ha (lib [Al]/acer) per spray. In 1994 and 1995,1% malathion granules at 11.1 kg/ha of granules significantly reduced corn ear insect pests in 2 different corn varieties. No significant effect on coccinellid or Orius spp. numbers was noted compared with untreated plots when the malathion granules were used. Over the top treatments of 0.1-10% granular malathion at 11.1 kg/ha of granules were less effective in controlling ear feeding insects at another site in 1994 compared with the multiple sprays of malathion applied to the ear zone. However, when granules were applied at ear level in 1995, equal or greater control of ear-feeding insects compared with the conventional malathion sprays was noted, depending on the level of active ingredients in the granules. All active ingredients rates of granules had no significant effect on coccinellids compared with untreated plots in 1995, but the conventional malathion sprays killed up to 95% of the coccinellids. When properly applied, these adherent granules should provide acceptable control of many ear-feeding insects in field corn, be more selective toward predators, and use lower levels of active ingredient compared with conventional malathion sprays. [ABSTRACT FROM PUBLISHER]

Vibration white finger or hand-arm vibration syndrome is the episodic blanching of the fingers in response to cold occurring in those who work with hand held vibrating tools. Clinically the condition differs from primary Raynaud's phenomenon as persistent paraesthesiae and pain are common in the hands and arms and these occur independently from the 'white attacks'. Symptoms can become severe enough to warrant a change of occupation. Industrial compensation may be awarded for vibration white finger but, at present, no simple or reliable objective diagnostic test is available. Calcitonin gene-related peptide (CGRP) is a neuropeptide with powerful vasodilator properties. A deficiency of immunoreactive CGRP nerve fibres has been previously demonstrated in the digital cutaneous microvasculature of patients with primary and secondary Raynaud's phenomenon with the distribution and quantity of other types of nerve fibres not being significantly altered. To determine if the innervation of the cutaneous microvasculature in vibration white finger was also abnormal skin biopsy samples from the fingers of 15 patients with vibration white finger, six healthy age matched controls who worked with vibrating machinery and 26 healthy age matched controls who were heavy manual workers without exposure to vibrating machinery were examined by immunohistochemistry. To try to correlate any histological abnormalities with clinical neurological deficit sensory nerve conduction studies have so far been performed in six patients with vibration white finger.(ABSTRACT TRUNCATED AT 250 WORDS) [ABSTRACT FROM AUTHOR]

A 1 year, prospective multicentre study was performed to investigate the efficacy and safety of intermittent treatment with cyclosporin in psoriasis vulgaris. Subjects received cyclosporin (Neoral®) 5 mg/kg per day until achieving 90% reduction in area affected, or for a maximum of 12 weeks. Those failing to demonstrate a satisfactory response were withdrawn. When further treatment was required, cyclosporin was recommenced. This cycle was repeated up to three times. Psoriasis activity was recorded using the area affected and sign scores for erythema, scaling and infiltration. Overall assessments of response and tolerability were recorded. Forty-one subjects, mean age 36, mean PASI 12.8, entered the first treatment period. Thirty-three received a second period of treatment and 16 a third. Eighteen failed to complete the study as planned: five were withdrawn due to adverse events, four due to treatment failure and nine due to protocol violations. At the end of each treatment period, significant improvements were seen in all efficacy parameters. Overall response was graded as `considerable improvement' or `minimal or no symptoms', by over 80% of subjects and investigators. Median intervals to relapse for subjects remaining in the study were 72 days (range 28-329) and 53 days (range 14-141) after periods 1 and 2, respectively. There were significant increases in mean serum creatinine and blood pressure during each treatment period. However, there were no significant differences in either parameter between baseline and the final follow-up visit. At the end of each treatment period, overall tolerability of the treatment was considered `good' or `very good' by over 80% of subjects and investigators. [ABSTRACT FROM AUTHOR]

Twelve patients with systemic sclerosis (SS) and severe Raynaud's phenomenon received infusions of prostaglandin E1 (PGE1) at a dose of 6-10 ng/kg/min, with either saline or 5% dextrose, for 72 hours in a single-blind cross-over study. The infusions were administered intravenously by centrally positioned catheters. Infusions were well tolerated with only mild side effects. Following the PGE1 infusion cold tolerance improved and attacks of Raynaud's phenomenon were less frequent, less severe, and shorter in duration. This subjective improvement was maintained for several weeks in most patients, and 2 noted healing of ischaemic ulcers. There was no significant change in objective measurements of hand function after either infusion. However, pain measured on a 10 cm visual analogue scale improved 2.19 cm with PGE1 and only 0.91 cm with normal saline (P less than 0.05). Temperature of the fingers and hands recorded by thermography did not change significantly with saline infusions, but did rise during PGE1 infusions (mean rise 2.0 degrees C at 48 hours, p less than 0.001), and was maintained when measured again 2 weeks later (mean rise 1.56 degrees C, p less 0.001). PGE1 may therefore be suitable treatment for Raynaud's phenomenon and the vascular insufficiency of systemic sclerosis and other connective tissue diseases. [ABSTRACT FROM AUTHOR]

A theoretical study of the general case of the estimation of regionalized variables with a lognormal distribution is presented. The results of this study are compared to those obtained assuming conservation of lognormality. The numerical significance of the different solutions is illustrated by several simple examples. [ABSTRACT FROM AUTHOR]

Twenty-eight patients with wide spectrum organ involvement of progressive systemic sclerosis but without signs or symptoms suggestive of cardiac involvement were studied by non-invasive cardiac techniques. The 12-lead electrocardiogram showed abnormalities in 6 patients: one had abnormal T waves and 5 had complete or incomplete right bundle branch block. Twenty-four hour ambulatory electrocardiography demonstrated higher average heart rates than in similar aged controls (82 +/- 9 vs 74 +/- 9 beats/min, P less than 0.05). In one patient a short run of ventricular tachycardia was recorded. No other significant arrhythmia was documented. Echocardiographic measurements were within normal ranges but small pericardial effusions were observed in two patients (7%). Resting first pass radionuclide angiography, utilizing 12 mCi of technetium 99m were performed in 23 patients. Seven patients (30%) had abnormal wall motion (diffuse hypokinesia), with a significant decrease in ejection fraction in comparison to those with normal wall motion (44 +/- 6% vs 60 +/- 6% P less than 0.01). Those with abnormal wall motion had suffered the disease longer than those with normal wall motion (13 +/- 4 vs 9.5 +/- 7 y). In conclusion, the heart is involved in half of the patients in this series; non-invasive cardiac assessment is useful in disclosing the early cardiac involvement and may influence long-term management. [ABSTRACT FROM PUBLISHER]

Transformation of 12-hydroxyoctadecanoic acid (12-HOA) to 5- n-hexyl-tetrahydrofuran-2-acetic acid (5-HTFA) by Bacillus lentus NRRL B-14864 (B-14864) was carried out in the presence or absence of oligomycin, 2-bromooctanoic acid (2-BA), or sodium azide. In addition, several saturated and monounsaturated monohydroxyfatty acids, saturated monooxofatty acids, and monounsaturated fatty acid were used as substrates for transformation reactions by B-14864 or corynebacterium FUI-2. Methyl esters of the transformation products were analyzed by gas chromatography and gas chromatography/mass spectroscopy. Various γ-lactones and tetrahydrofuran fatty acid derivatives were conversion products when saturated monohydroxyfatty acids were used as substrates; the production of 5-HTFA from 12-HOA by B-14864 cells was completely inhibited in the presence of high concentration of oligomycin, 2-BA, or sodium azide; and fatty acid β-oxidation metabolic intermediates, 6-hydroxydodecanoic, 4-oxododecanoic, and 4-oxodecanoic acids were products when 12-HOA, 10-oxo-, and 12-oxooctadecanoic acids were used as substrates. Our results suggest that the production of 5-HTFA from 12-HOA by B-14864 was through the fatty acid β-oxidation pathway. Three-day-old driedfruit beetle pupae were topically treated with 5-HTFA to test for juvenile hormone activity, and 5-HTFA was found to possess juvenile hormone-like activity in pure form but not when it was diluted to 10%. [ABSTRACT FROM AUTHOR]

Albright's syndrome is characterized by the combination of polyostotic fibrous dysplasia, precocious puberty and cafe-au-lait spots. We describe a patient with polyostotic fibrous dysplasia who also had extensive linear epidermal naevi, an association that has not been previously described in the English literature. [ABSTRACT FROM AUTHOR]

First-instar larvae of the false tobacco budworm (corn earworm, Helicoverpa zea) that fed on either intact plants, leaf disks from undamaged plants, or leaf disks from insect-damaged plants of Nicotiana sylvestris and N. tabacum Coker plants overproducing a tobacco anionic peroxidase generally caused significantly less damage than those caged with corresponding material from wild-type plants. In some cases mortality was significantly higher and weights significantly less for caterpillars feeding on leaf material from overproducing vs. wild-type plants. First-instar H. zea fed on the same type of leaf material from N. tabacum Xanthi underproducing tobacco anionic peroxidase generally caused significantly more damage than those fed leaf material from wild-type plants. However, first-instar H. zea fed on underexpressing leaf material from N. sylvestris did not cause significantly greater damage compared to wild-type material. In cases where peroxidase enzyme activity was determined, significantly higher mean peroxidase activity was seen in leaves of plant types that also had significantly less mean feeding ratings. This information suggests that peroxidase activity can contribute to leaf resistance to chewing insects. However, the context of the peroxidase (cooccurring substrates, additional inducible factors) can mediate the degree of influence seen by changes in individual peroxidase isozyme levels. [ABSTRACT FROM AUTHOR]

The arachidonate lipoxygenase products 12-hydroxy-5, 8,10,14-eicosatetraenoic acid (12-HETE) and 5(S),12(R)-dihydroxy-6,8,10,14-eicosatetraenoic acid (leukotriene B4, LTB4) are potent leucocyte chemoattractants in vitro and in vivo. Both 12-HETE and LTB4-like material are found in increased amounts in lesional skin in psoriasis. Epicutaneous administration of 12(R,S)-HETE and LTB4 in normal skin evokes neutrophil and mononuclear dermal infiltrates accompanied by collections of neutrophils in the epidermis. Similar appearances result from the application of LTB4 to uninvolved skin in psoriasis. We have now investigated the effects of single and multiple epicutaneous applications of 12(R,S)-HETE and LTB4, both alone and in combination, in normal human skin and in clinically uninvolved skin of patients with psoriasis. As in the case of LTB4, erythematous responses to 12(R,S)-HETE were similar in normal skin and in psoriasis. Similar neutrophil polymorphonuclear responses were evoked by topical application of 50 ng LTB4 and 20 μg 12(R,S)-HETE. Application of the combination of 12(R,S)-HETE and LTB4 evoked only a partially additive erythematous response, and no evidence of an additive neutrophilotactic response was detected histologically. Multiple applications resulted in tolerance both clinically and histologically. Cross tolerance to 12(R,S)-HETE and LTB4 occurred in the majority of subjects. These results suggests that both 12(R,S)-HETE and LTB4 may be important in the production and control of the magnitude of the inflammatory events in psoriasis. [ABSTRACT FROM AUTHOR]

The channel assignment problem has become increasingly important in mobile telephone communication. Since the usable range of the frequency spectrum is limited, the optimal assignment problem of channels has become increasingly important. Recently Genetic Algorithms (GAs) have been proposed as new computational tools for solving optimization problems. GAs are more attractive than other optimization techniques, such as neural networks or simulated annealing, since GAs are generally good at finding an acceptably good global optimal solution to a problem very quickly. In this paper, a new channel assignment algorithm using GAs is proposed. The channel assignment problem is formulated as an energy minimization problem that is implemented by GAs. Appropriate GAs operators such as reproduction, crossover and mutation are developed and tested. In this algorithm, the cell frequency is not fixed before the assignment procedures as in the previously reported channel assignment algorithm using neural networks. The average generation numbers and the convergence rates of GAs are shown as a simulation result. When the number of cells in one cluster are increased, the generation numbers are increased and the convergence rates are decreased. On the other hand, with the increased minimal frequency interval, the generation numbers are decreased and the convergence rates are increased. The comparison of the various crossover and mutation techniques in a simulation shows that the combination of two points crossover and selective mutation technique provides better results. All three constraints are also considered for the channel assignments: the co-channel constraint, the adjacent channel constraint and the co-site channel constraint. The goal of this paper is the assignment of the channel frequencies which satisfied these constraints with the lower bound number of channels. [ABSTRACT FROM AUTHOR]

It has previously been shown that the inherently tumor necrosis factor-α (TNF-α)-sensitive L929 murine fibroblast cell line becomes much more sensitive to the cytotoxic effect of this cytokine after exposure to Mycobacterium tuberculosis in culture. In this study it is now shown that normal human cells of types likely to be involved in tuberculous lesions are affected in a similar way. Growth of normal human fibroblasts is usually stimulated by TN F-α in vitro, but after exposure to M. tuberculosis or to extracts of this organism, these cells are killed rather than stimulated by subsequent exposure to TNF-α Similarly, human endothelial cells become susceptible to doses to TNF-α which do not normally affect viability. Moreover this enhancement of sensitivity to TNF-α is not confined to its toxicity. Endothelial cells and HeLa cells exposed to M. tuberculosis express increased levels of ICAM- 1 after subsequent exposure to TNF-α. implying synergy between the two stimuli. It is suggested that these effects contribute to the ability of M. tuberculosis to distort the normal protective role of TN F-α so that the cytokine becomes detrimental to the host. [ABSTRACT FROM AUTHOR]

Fifteen patients with primary Raynaud's phenomenon received captopril 25 mg or placebo, three times daily for 6 weeks, in a randomized double-blind cross-over study. Compared with placebo, captopril produced a significant improvement in cutaneous blood flow but did not alter the frequency or severity of attacks of Raynaud's phenomenon. [ABSTRACT FROM AUTHOR]

The article examines the role of acidic lipid neutrophil chemo-attractant in the pathogenesis of the inflammatory changes in chronic plaque psoriasis. The evidence obtained to date is presented here in six sections, according to the above criteria. The article informs about the process to recover lipoxygenase products from psoriatic lesions. In order to recover such compounds, a skin chamber sampling technique has been developed. It also states that psoriasisis not a multifactorial disease. LTB4-like material and 12-HETE have been recovered from psoriatic lesions and from calcium ionophore stimulated human epidermal cell suspensions. These two compounds, applied topically, have also been shown to reproduce some features of the psoriatic lesion.

The merits of oral ketoconazole and griseofulvin in dermatophytosis have been compared in a double blind study on 74 patients with 152 infected sites. The initial daily doses were 200 mg and 500 mg respectively, but these were doubled after 3 months if there was an inadequate clinical response. Treatment was continued either until clinical and mycological remission was achieved or a year of therapy had been given. Seventy-five per cent (total 80) and 74% (total 72) of all infected sites treated with ketoconazole and griseofulvin respectively were cleared of infection. However, in toe nail infections the respective cure rates were only 21% and 17%. Ketoconazole appeared to act more rapidly in curing tinea corporis or tinea cruris due to Trichophyton rubrum, whereas griseofulvin was superior in T. interdigitale infections. No serious side-effects were encountered in either treatment group. In view of the slight risk of drug-induced hepatitis, ketoconazole is best reserved as a second-line drug for toe nail infections unless there are specific indications, such as griseofulvin intolerance. In these cases liver function tests should be monitored regularly throughout therapy. [ABSTRACT FROM AUTHOR]

The case history of a patient who presented with erythema annulare centrifugum and white banding of the toe nails is recorded. On investigation for an underlying malignancy the patient was found to have an opacity in the lower lobe of the right lung. Subsequently lobectomy was performed and histology of the operative specimen revealed a malignant carcinoid tumour of the bronchus. [ABSTRACT FROM AUTHOR]