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PubMed2002

The evolving market structures of gambling: case studies modelling the socioeconomic assignment of gaming machines in Melbourne and Sydney, Australia.

The expansion of gambling industries worldwide is intertwined with the growing government dependence on gambling revenue for fiscal assignments. In Australia, electronic gaming machines (EGMs) have dominated recent gambling industry growth. As EGMs have proliferated, growing recognition has emerged that EGM distribution closely reflects levels of socioeconomic disadvantage. More machines are located in less advantaged regions. This paper analyses time-series socioeconomic distributions of EGMs in Melbourne, Australia, an immature EGM market, and then compares the findings with the mature market in Sydney. Similar findings in both cities suggest that market assignment of EGMs transcends differences in historical and legislative environments. This indicates that similar underlying structures are evident in both markets. Modelling the spatial structures of gambling markets provides an opportunity to identify regions most at risk of gambling related problems. Subsequently, policies can be formulated which ensure fiscal revenue from gambling can be better targeted towards regions likely to be most afflicted by excessive gambling-related problems.

Australia↗
PubMed1998

Optimization of beam orientation in radiotherapy using planar geometry.

This paper proposes a new geometrical formulation of the coplanar beam orientation problem combined with a hybrid multiobjective genetic algorithm. The approach is demonstrated by optimizing the beam orientation in two dimensions, with the objectives being formulated using planar geometry. The traditional formulation of the objectives associated with the organs at risk has been modified to account for the use of complex dose delivery techniques such as beam intensity modulation. The new algorithm attempts to replicate the approach of a treatment planner whilst reducing the amount of computation required. Hybrid genetic search operators have been developed to improve the performance of the genetic algorithm by exploiting problem-specific features. The multiobjective genetic algorithm is formulated around the concept of Pareto optimality which enables the algorithm to search in parallel for different objectives. When the approach is applied without constraining the number of beams, the solution produces an indication of the minimum number of beams required. It is also possible to obtain non-dominated solutions for various numbers of beams, thereby giving the clinicians a choice in terms of the number of beams as well as in the orientation of these beams.

Algorithms↗
PubMed2003

The role of iodine in antisepsis and wound management: a reappraisal.

For more than 150 years, iodine has been used for the prevention of infection and for the treatment of wounds. Nowadays a large amount of published evidence is available and, although it is generally in support of the use of iodine product, it is confused by being a mixture of laboratory, animals and human studies, often using different preparations. This makes interpretation and comparison difficult. After new developments and publications, the role of iodine in antisepsis and in wound management needs to be reevaluated. We mainly focused our review on the following problems: the role of the newly developed formulations of iodine preparations, its antimicrobial activity, the possibility of impairing the wound healing process, the role of iodine in the problem of growing resistance against antibiotics and antiseptics. New formulations seem to keep the same clinical efficacy, avoiding the problem of toxicity; it seems that the antibacterial activity of iodine is superior compared to other products and, in contrast with antibiotics and other antiseptics, it seems to have no resistance problem. It seems that povidone-iodine has all the characteristics to become the first choice antiseptic in wound treatment.

Anti-Infective Agents, Local↗
PubMed2005

Reserve selection using nonlinear species distribution models.

Reserve design is concerned with optimal selection of sites for new conservation areas. Spatial reserve design explicitly considers the spatial pattern of the proposed reserve network and the effects of that pattern on reserve cost and/or ability to maintain species there. The vast majority of reserve selection formulations have assumed a linear problem structure, which effectively means that the biological value of a potential reserve site does not depend on the pattern of selected cells. However, spatial population dynamics and autocorrelation cause the biological values of neighboring sites to be interdependent. Habitat degradation may have indirect negative effects on biodiversity in areas neighboring the degraded site as a result of, for example, negative edge effects or lower permeability for animal movement. In this study, I present a formulation and a spatial optimization algorithm for nonlinear reserve selection problems in grid-based landscapes that accounts for interdependent site values. The method is demonstrated using habitat maps and nonlinear habitat models for threatened birds in the Netherlands, and it is shown that near-optimal solutions are found for regions consisting of up to hundreds of thousands grid cells, a landscape size much larger than those commonly attempted even with linear reserve selection formulations.

Algorithms↗
PubMed1998

A new three-dimensional finite-difference bidomain formulation for inhomogeneous anisotropic cardiac tissues.

Bidomain modeling of cardiac tissues provides important information about various complex cardiac activities. The cardiac tissue consists of interconnected cells which form fiber-like structures. The fibers are arranged in different orientations within discrete layers or sheets in the tissue, i.e., the fibers within the tissue are rotated. From a mathematical point of view, this rotation corresponds to a general anisotropy in the tissue's conductivity tensors. Since the rotation angle is different at each point, the anisotropic conductivities also vary spatially. Thus, the cardiac tissue should be viewed as an inhomogeneous anisotropic structure. In most of the previous bidomain studies, the fiber rotation has not been considered, i.e., the tissue has been modeled as a homogeneous orthotropic medium. In this paper, we describe a new finite-difference bidomain formulation which accounts for the fiber rotation in the cardiac tissue and hence allows a more realistic modeling of the cardiac tissue. The formulation has been implemented on the data-parallel CM-5 which provides the computational power and the memory required for solving large bidomain problems. Details of the numerical formulation are presented together with its validation by comparing numerical and analytical results. Some computational performance results are also shown. In addition, an application of this new formulation to provide activation patterns within a tissue slab with a realistic fiber rotation is demonstrated.

Algorithms↗
PubMed1988

Dealing with uncertainty, risks, and tradeoffs in clinical decisions. A cognitive science approach.

To generate hypotheses about how physicians make difficult clinical decisions, we analyzed transcripts of the "thinking aloud" behavior of expert clinicians making a testing or treatment decision with an uncertain diagnosis. We compared the clinicians' reasoning with a decision analysis of the same problem. The experts did not formulate a global outline of their decision, but chained together a sequence of decisions based on available and incomplete information. Despite effective and efficient problem solving, the clinicians used numeric terms only as symbolic representations of likelihood, used limited information in choosing among alternatives, and dismissed the possibility that a less conventional strategy, empiric therapy, might yield equivalent outcome. We describe cognitive problem-solving strategies and knowledge representations that permit persons to make successful decisions despite limited processing resources. The same cognitive procedures probably contribute to observed errors in decision-making under uncertainty.

Amphotericin B↗
PubMed2004

Electrical conductivity imaging using gradient B, decomposition algorithm in magnetic resonance electrical impedance tomography (MREIT).

In magnetic resonance electrical impedance tomography (MREIT), we try to visualize cross-sectional conductivity (or resistivity) images of a subject. We inject electrical currents into the subject through surface electrodes and measure the z component Bz of the induced internal magnetic flux density using an MRI scanner. Here, z is the direction of the main magnetic field of the MRI scanner. We formulate the conductivity image reconstruction problem in MREIT from a careful analysis of the relationship between the injection current and the induced magnetic flux density Bz. Based on the novel mathematical formulation, we propose the gradient Bz decomposition algorithm to reconstruct conductivity images. This new algorithm needs to differentiate Bz only once in contrast to the previously developed harmonic Bz algorithm where the numerical computation of (inverted delta)2Bz is required. The new algorithm, therefore, has the important advantage of much improved noise tolerance. Numerical simulations with added random noise of realistic amounts show the feasibility of the algorithm in practical applications and also its robustness against measurement noise.

Algorithms↗
PubMed2005

Pharmacokinetics of theophylline after administration of suppositories formulation.

Asthma is a public health problem for developed countries. It attacks all age groups but often starts in childhood. Theophylline ethanoate of piperazine in a suppository form is one of the treatments of asthmatic children. The pharmacokinetics of theophylline were evaluated in 24 healthy male subjects after administration of theophylline ethanoate of piperazine suppositories (PR) (Minophylline 500 mg. Alexandria Co.) and single injection intravenous (IV) of theophylline ethanoate of piperazine (Minophylline ampoules 500 mg Alexandria Co.). The theophylline serum levels were determined by an ELISA method. Peak theophylline plasma concentration, Cmax, (mean +/- S.D) was 21.5 +/- 2.10 microg/mL & 14 +/- 0.90 microg/mL; AUC(0-t), values were 80.9 and 67. 4 microg x ml x hr for the reference IV preparation and suppositories, respectively. The median peak time, Tmax, was 0.5 hr for theophylline rectal administration. The above mentioned results demonstrate the possibilities of using theophylline (Minophylline Suppositories--500 mg Alexandria Co.) in asthmatic children in rural and desert areas away from health care personnel.

Administration, Rectal↗
PubMed1980

Detection of HLA haplotype associations with disease.

In a recent paper, Thomson & Bodmer (1979) explored several conceptual and analytic issues involved in studying the association of HLA haplotypes with disease. One key problem they emphasized was the assessment of the statistical significance of the third order linkage disequilibrium between two HLA genes and a disease susceptibility gene. We have formulated an approach to this problem and illustrate this approach by deriving such statistical tests of true haplotype associations for two models of disease susceptibility previously studied by Terasaki & Mickey (1975) and by Thomson & Bodmer (1977). A numerical example using actual phenotypic data is then presented to demonstrate the practicality of the methods.

Alleles↗
PubMed2005

When do children convert from liquid antiretroviral to solid formulations?

BACKGROUND: Liquid formulations are usually regarded as the gold standard in paediatric formulation; but sometimes, liquid formulations have stability and taste problems as well as being inconvenient for travelling. Therefore, for the management of long-term illness, some older children, parents and clinicians would prefer to use solid formulations. However, there is a lack of studies to investigate the age at which children are converted from liquid to solid formulations. OBJECTIVES: (1) To investigate the age range at which children convert from liquid antiretroviral drug formulations to solid formulations, the formulations are abacavir, didanosine, lamivudine, stavudine, and zidovudine. (2) To calculate how long children stay on each of five UK liquid formulations (retention time) and factors affecting the retention times of the above liquid formulations. METHOD: This was a retrospective medical records survey at Great Ormond Street Hospital for Children, London, United Kingdom. Patients' treatment details were entered into SPSS for Windows v. 11.0 and the retention times for the above liquid formulations were calculated i.e., from initiation of the liquid treatment to conversion to solid preparation. The retention times of different preparations were then compared using Cox regression analysis. RESULTS: A total of 92 patients are included in the analysis. The overall average age at conversion was 7.3 years (95% CI 6.3-8.2). Patients on stavudine were more likely to switch to the corresponding solid dose form than the other four medicines (P < 0.001); more than 50% of patients on stavudine switched to solid formulation after nine months of treatment, however, less than 25% of patients on other formulations switched during the same period. CONCLUSION: Children taking antiretroviral liquid preparations change to solid dose forms at approximately seven years of age. However, for stavudine, children are more likely to take the solid form at an earlier age.

Age Factors↗
PubMed2003

Vivitrex, an injectable, extended-release formulation of naltrexone, provides pharmacokinetic and pharmacodynamic evidence of efficacy for 1 month in rats.

While oral naltrexone is effective in treating alcohol and opiate dependencies, poor patient adherence and widely fluctuating plasma levels limit its efficacy. To overcome these problems, an extended-release formulation of naltrexone (Vivitrex) was developed by encapsulating naltrexone into injectable, biodegradable polymer microspheres. Pharmacokinetic studies in rats demonstrated that this formulation produced stable, pharmacologically relevant plasma levels of naltrexone for approximately 1 month following either subcutaneous or intramuscular injections. While rats receiving placebo microspheres demonstrated a pronounced analgesic response to morphine in the hot-plate test, morphine analgesia was completely blocked in rats treated with extended-release naltrexone. This antagonism began on day 1 following administration and lasted for 28 days. Rats reinjected with extended-release naltrexone 34 days after the initial dose and tested for another 35 days showed consistent suppression of morphine analgesia for an additional 28 days. mu-Opioid receptor density, as measured by [(3)H]DAMGO autoradiography, increased up to two-fold following a single injection of extended-release naltrexone. Saturation binding assays using [(3)H]DAMGO showed changes in the midbrain and striatum at 1 week after extended-release naltrexone administration, and after 1 month in the neocortex. These receptor increases persisted for 2-4 weeks after dissipation of the morphine antagonist actions of naltrexone. These data suggest that therapeutically relevant plasma levels of naltrexone can be maintained using monthly injections of an extended-release microsphere formulation, and that changes in mu-opioid receptor density do not impact its efficacy in suppressing morphine-induced analgesia in the rat. Clinical trials of extended release naltrexone for treating alcohol and opiate dependency are currently ongoing.

Animals↗
PubMed2005

Automatic detection of subsystem/pathway variants in genome analysis.

MOTIVATION: Proteins work together in pathways and networks, collectively comprising the cellular machinery. A subsystem (a generalization of pathway concept) is a group of related functional roles (such as enzymes) jointly involved in a specific aspect of the cellular machinery. Subsystems provide a natural framework for comparative genome analysis and functional annotation. A subsystem may be implemented in a number of different functional variants in individual species. In order to reliably project functional assignments across multiple genomes, we have to be able to identify the variants implemented in each genome. The analysis of such variants across diverse species is an interesting problem by itself and may provide new evolutionary insights. However, no computational techniques are presently available for an automated detection and analysis of subsystem variants. RESULTS: Here we formulate the subsystem variant detection problem as finding the minimum number of subgraphs of a subsystem, which is represented as a graph, and solve the optimization problem by integer programming approach. The performance of our method was tested on subsystems encoded in the SEED, a genomic integration platform developed by the Fellowship for Interpretation of Genomes as a component of a large-scale effort on comparative analysis and annotation of multiple diverse genomes. Here we illustrate the results obtained for two expert-encoded subsystems of the biosynthesis of Coenzyme A and FMN/FAD cofactors. Applications of variant detection, to support genomic annotations and to assess divergence of species, are briefly discussed in the context of these universally conserved and essential metabolic subsystems. SUPPLEMENTARY INFORMATION: The details of the variant detection results are available at http://ffas.burnham.org/svar/supp.html.

Animals↗
PubMed2004

Practical application of pharmacotherapy with long-acting risperidone for patients with schizophrenia.

OBJECTIVE: It is now generally accepted that the use of second-generation, or atypical, antipsychotics for schizophrenia represents an advance over conventional antipsychotic agents. However, adherence continues to be a problem, as with other medications for chronic disorders. Long-acting formulations of conventional antipsychotics partly address adherence problems, but their use is limited by tolerability issues. This article provides practical advice to physicians on the characteristics of patients who would benefit from treatment with long-acting atypical antipsychotic agents and offers suggestions on how to initiate treatment. METHODS: A literature search for studies published between 1980 and 2003 that evaluated the treatment of patients with schizophrenia with long-acting atypical agents was conducted by using MEDLINE and EMBASE. The primary search parameters were "schizophrenia," "atypical," "antipsychotic," and "long-acting." As expected, long-acting risperidone was the only long-acting atypical agent identified; thus this article focuses on practical advice and suggestions on how to initiate therapy with long-acting risperidone. RESULTS AND DISCUSSION: From the results of the literature search and the discussion of a panel of experts at a meeting held in Dublin in 2003 and supported by Johnson & Johnson, it is possible to conclude that long-acting risperidone has demonstrated efficacy and tolerability, even among patients who are considered clinically stable on other antipsychotics. Most patients can switch safely and effectively to long-acting risperidone if appropriate strategies are applied. Long-acting risperidone provides a new and promising therapeutic option for the treatment of schizophrenia.

Antipsychotic Agents↗
PubMed2001

Model sustainability in DSS design and scenario formulation: what are the right scenarios?

A concept of the integrated approach in designing multidisciplinary decision support systems (DSS) based on agricultural scenarios for sustainable catchment management is discussed. A principle of holism underlying the integrated approach to DSS design is formulated. For a model to be viable and sustainable, it should be based on scenarios that are plausible and highly typical from the point of view of those 'doing' agriculture. Problems concerning principles of scenario formulation within the integrated approach are considered. A notion of 'prototype' scenarios based on 'joint venture' of modellers and stakeholders is proposed.

Agriculture↗
PubMed2000

[A hearing in prison: health needs perceived by women deprived of freedom].

OBJECTIVE: To identify the perceived necessities and proposals for health action of women committed to a detention centre. DESIGN: A study of needs through a method of social intervention, the hearing. SETTING: The detention centre of the penitentiary of Valencia (Picassent). The area of application is primary care in the penitentiary. PARTICIPANTS: 38 women were chosen on criteria of proportional representation in line with the profile of the total number of women (112) who lived in module 8 of the centre, and according to agreed defining variables such as age, ethnic background and drugs consumption. RESULTS: The women's replies showed they had an integrated view of the concept of health. They identified HIV/AIDS infection, drugs and food as the health problems that most concerned them; and formulated proposals aiming at actions on these and other aspects such as personal relationships, psychological problems and their surrounds. CONCLUSIONS: The method employed was shown to be useful for identifying the needs and proposals of women deprived of liberty. This information could certainly be used to discuss and rework with the inmates themselves, so as to win their participation in the actions decided on.

Female↗
PubMed2003

Dielectric profile variations in high-index-contrast waveguides, coupled mode theory, and perturbation expansions.

Perturbation theory formulation of Maxwell's equations gives a theoretically elegant and computationally efficient way of describing small imperfections and weak interactions in electromagnetic systems. It is generally appreciated that due to the discontinuous field boundary conditions in the systems employing high dielectric contrast profiles standard perturbation formulations fails when applied to the problem of shifted material boundaries. In this paper we developed coupled mode and perturbation theory formulations for treating generic perturbations of a waveguide cross section based on Hamiltonian formulation of Maxwell equations in curvilinear coordinates. We show that our formulation is accurate beyond the first order and rapidly converges to an exact result when used in a coupled mode theory framework even for the high-index-contrast discontinuous dielectric profiles. Among others, our formulation allows for an efficient numerical evaluation of such quantities as deterministic PMD and change in the GV and GVD of a mode due to generic profile distortion in a waveguide of arbitrary cross section. To our knowledge, this is the first time perturbation and coupled mode theories are developed to deal with arbitrary profile variations in high-index-contrast waveguides.

Journal Article↗
PubMed2003

Identification of regulatory binding sites using minimum spanning trees.

Recognition of protein-binding sites from the upstream regions of genes is a highly important and unsolved problem. In this paper, we present a new approach for studying this challenging issue. We formulate the binding-site recognition problem as a cluster identification problem, i.e., to identify clusters in a data set that exhibit significantly different features (e.g., density) than the overall background of the data set. We have developed a general framework for solving such a cluster identification problem. The foundation of the framework is a rigorous relationship between data clusters and subtrees of a minimum spanning tree (MST) representation of a data set. We have proposed a formal and general definition of clusters, and have demonstrated that a cluster is always represented as a connected component of the MST, and further it corresponds to a substring of a linear representation of the MST. Hence a cluster identification problem is reduced to a problem of finding substrings with certain features, for which algorithms have been developed. We have applied this MST-based cluster identification algorithm to a number of binding site identification problems. The results are highly encouraging.

Algorithms↗
PubMed2001

A new method for true and spurious eigensolutions of arbitrary cavities using the combined Helmholtz exterior integral equation formulation method.

Integral equation methods have been widely used to solve interior eigenproblems and exterior acoustic problems (radiation and scattering). It was recently found that the real-part boundary element method (BEM) for the interior problem results in spurious eigensolutions if the singular (UT) or the hypersingular (LM) equation is used alone. The real-part BEM results in spurious solutions for interior problems in a similar way that the singular integral equation (UT method) results in fictitious solutions for the exterior problem. To solve this problem, a Combined Helmholtz Exterior integral Equation Formulation method (CHEEF) is proposed. Based on the CHEEF method, the spurious solutions can be filtered out if additional constraints from the exterior points are chosen carefully. Finally, two examples for the eigensolutions of circular and rectangular cavities are considered. The optimum numbers and proper positions for selecting the points in the exterior domain are analytically studied. Also, numerical experiments were designed to verify the analytical results. It is worth pointing out that the nodal line of radiation mode of a circle can be rotated due to symmetry, while the nodal line of the rectangular is on a fixed position.

Journal Article↗