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At least 127 records · Page 7Linked to original sources
PubMed2005

Systematic procedure for designing processes with multiple environmental objectives.

Evaluation of multiple objectives is very important in designing environmentally benign processes. It requires a systematic procedure for solving multiobjective decision-making problems due to the complex nature of the problems, the need for complex assessments, and the complicated analysis of multidimensional results. In this paper, a novel systematic procedure is presented for designing processes with multiple environmental objectives. This procedure has four steps: initialization, screening, evaluation, and visualization. The first two steps are used for systematic problem formulation based on mass and energy estimation and order of magnitude analysis. In the third step, an efficient parallel multiobjective steady-state genetic algorithm is applied to design environmentally benign and economically viable processes and to provide more accurate and uniform Pareto optimal solutions. In the last step a new visualization technique for illustrating multiple objectives and their design parameters on the same diagram is developed. Through these integrated steps the decision-maker can easily determine design alternatives with respect to his or her preferences. Most importantly, this technique is independent of the number of objectives and design parameters. As a case study, acetic acid recovery from aqueous waste mixtures is investigated by minimizing eight potential environmental impacts and maximizing total profit. After applying the systematic procedure, the most preferred design alternatives and their design parameters are easily identified.

Algorithms↗
PubMed2005

Generalized principles of unchanging total concentration.

We consider the transport of multiple reacting species under the continuum assumption in situations such as those that frequently arise in electroanalytical chemistry. Under certain limitations, it has been shown that the total species concentration (as defined by Oldham and Feldberg) of such a system is uniform and constant. In this work, we extend the limits of the previous analysis to enable greater applicability. This is accomplished by using either of two new dependent variables, which are generalizations of the concept of total concentration. Then, conditions are determined under which the dependent variable will be uniform and constant in time. From a practical viewpoint, the described formalism allows one to simplify the multispecies transport problem formulation by eliminating one equation from the system of governing equations.

Chemistry Techniques, Analytical↗
PubMed1997

Characteristics and significance of the amorphous state in pharmaceutical systems.

The amorphous state is critical in determining the solid-state physical and chemical properties of many pharmaceutical dosage forms. This review describes the characteristics of the amorphous state and some of the most common methods that can be used to measure them. Examples of pharmaceutical situations where the presence of the amorphous state plays an important role are presented. The application of our current knowledge to pharmaceutical formulation problems is illustrated, and some strategies for working with amorphous character in pharmaceutical systems are provided.

Chemistry, Pharmaceutical↗
PubMed1997

Validation of a Questionnaire to Screen University Students for Learning Disabilities.

Learning disabilities (LD) may cause academic failures among university students, but minor accommodations may in some instances allow students to progress satisfactorily. The current study validates a questionnaire for detecting students likely to have an LD. University students, 57 with a documented LD and 134 without, completed a Likert-scale questionnaire to assess the degree of self-perceived difficulty for 50 learning or testing situations. Wilcoxon rank sum test, separate logistic regression models, and determination of the best joint set of predictors of LD were carried out. The mean per-item questionnaire score was higher in the LD group (p < 0.0001); 47 individual items were significant predictors (i.e., p < 0.05) of LD status. The best joint set of predictors consisted of items dealing with word pronunciation, comprehending mathematical word problems, formulating summaries, spelling, slow reading rate, finishing tests in the allotted time, note-taking in lectures, and falling asleep while reading. Incorporating responses to these eight items, a formula was derived to determine the probability of LD. Taking 0.26 as the threshold for predicting the presence of an LD, the sensitivity of the questionnaire was 88%, the specificity was 87% for this population. The questionnaire could be an effective screening tool to detect university or professional students who should consider comprehensive testing for LD.

Journal Article↗
PubMed1999

Towards the safer use of non-steroidal anti-inflammatory drugs.

Musculoskeletal conditions afflict most of us at some time in our lives, and we all have relatives and friends who suffer the pain and disability sometimes associated with conditions such as back or neck pain, fibrositis and osteoarthritis. The goal of those of us who try to help individuals with these conditions is to achieve effective, but also safe, management of their musculoskeletal disorders, the commonest symptom of which is pain. This goal can be achieved by better diagnosis and problem formulation (allowing better selection of treatment options); informed selection of non-drug and drug therapeutic options, based on relative cost-benefit considerations; and the judicious, appropriate and safe use of drugs, particularly non-steroidal anti-inflammatory drugs (NSAID). Setting realistic goals and maintaining regular surveillance of patients are also important considerations. Finally, the active involvement of the patient in their own management is associated with better and safer outcomes.

Aged↗
PubMed1987

Diagnosis and intervention in young children: the continuing gap.

Modern diagnostic systems have replaced theory-based, highly inclusive, explanatory terminology with descriptions of symptoms at low levels of inference often empirically determined. This shift has caused, inadvertently, an increased rift between diagnosis and treatment in young children. It is argued that the primary purpose of a diagnostic system is guidance for intervention; this was provided by the omnibus terminology of the early 1900s but is sacrificed when we revert to skin-level descriptors. Treatment of young children, as a result, is largely determined today by intervention philosophies, not by child diagnostic specification. To heal the rift, a proposal is offered for diagnoses in the form of problem formulations--statements of deficiencies in terms of hypothesized interventions--based on what is most central or amenable to change.

Arousal↗
PubMed2000

Prediction of Individual Muscle Forces Using Lagrange Multipliers Method - A Model of the Upper Human Limb in the Sagittal Plane: I. Theoretical Considerations.

Analytical solutions of indeterminate problems formulated for biomechanical models with more than one degree of freedom (DOF) are rarely found. This paper is an extension of the investigations of a 1 DOF model (Raikova, 1996, J. Biomechanics, 763-772) for a more complex 3 DOF model. The proposed model of the human upper limb is in the sagittal plane and includes ten muscle elements, four of them being two-joint ones. The formulated optimization task is solved analytically using the method of Lagrange multipliers. It is supposed that the optimization function is complex but can be approximated by a weighted sum of the squared muscle forces, where the nature of the weight factors of the muscles are unknown. The proposed computational algorithm for determination of the unknown individual muscle forces and joint reactions is easily implemented and may be extended without difficulties for more DOF and muscles. The aim is to establish a means of investigation of the possible weight coefficients for different modelled situations, which will help in searching for their physiological interpretation and analytical description.

Journal Article↗
PubMed2000

Prediction of Individual Muscle Forces Using Lagrange Multipliers Method - A Model of the Upper Human Limb in the Sagittal Plane: II. Numerical Experiments and Sensitivity Analysis.

Using the method of Lagrange multipliers an analytical solution of the optimization problem formulated for a two-dimensional, 3DOF model of the human upper limb has been described in Part I of this investigation. The objective criterion used is the following: [formula: see text], where F(i) -s are the muscle forces modelled and c(i) -s are unknown weight factors. This study is devoted to the numerical experiments performed in order to investigate which sets of the weight factors may predict physiologically reasonable muscle forces and joint reactions. A sensitivity analysis is also presented. The influence of: the gravity forces, different external loads applied to the hand, changes of the weight factors and of joint angle on the optimal solution is studied. A general conclusion may be drawn: using the above mentioned objective criterion, practically all motor tasks performed by the human upper limb may be described if the c(i) -s are properly chosen. These weight factors generally depend on the joint moments and must be different (their magnitudes as well as their signs) for agonistic muscles and for their antagonists.

Journal Article↗
PubMed2002

A comparative analysis based on different strength criteria for evaluation of risk factor for dental implants.

A numerical analysis is developed to study the interaction phenomena between endousseus titanium dental implants and surrounding jawbone tissue. The interest is focused on the most appropriate evaluation of the stress state arising in the tissue because of the implant under physiological loading. The problem is considered with regard to linear elastic response of the one and to short time effect. Different configurations of bone-implant system are described, using axial-symmetrical and three-dimensional models, by means of finite and geometric element method. The investigation attains to the stress states induced in bone that lead to a limit condition near the effective failure surface. The parameter commonly adopted in literature, such as the Von Mises stress, represents an excessive simplification of problem formulation, leading to an incorrect evaluation of the real failure risk for the implant, due to the assumption of the isotropic and deviatoric nature of the adopted stress measure. More suitable criterion can be assumed, such as the Tsai-Wu criterion, to take into account the anisotropy that characterises the response of bone, as well as the influence of a hydrostatic stress state. The analysis developed offers a comparison of results by using different criteria, leading to an evaluation of reliability of the procedure to be followed and addressing also to an evaluation of a risk factor for the implant investigated.

Anisotropy↗
PubMed1995

A risk assessment for lead in birds.

Ecotoxicologists and ecologists have examined the effects of pollutants on individuals and populations largely in terms of one or only a few effects. Yet the recent trend toward a holistic approach to ecological risk assessment suggests that a rigorous paradigm should be applied to toxicants, from hazard identification to risk characterization. Recent discussions have recognized that an up-front problem formulation phase is more critical in ecological risk assessment than it is for human health risk assessment. In this article a modified environmental health risk assessment paradigm is used to examine the risk of lead to birds. This risk analysis is largely conceptual, based on laboratory and field data, and incorporates information currently available. The model expands the hazard identification phase to create a target identification phase that includes the identification of receptors, endpoints, relationships, spatial and temporal scales, and indicators. The target identification phase is unique to the particular hazard, species, population, or community being examined. Lead can cause mortality, or can indirectly affect populations through effects on the food base, avian behavior, reproductive success, and recruitment. Lead can (1) decrease the abundance and availability of prey, (2) bioaccumulate in prey causing increased lead toxicosis in predators, or (3) increase prey availability by interfering with its hiding or escape behavior. Moreover, lower abundance of prey can lead to starvation or nutrient deficiencies, which amplify the absorption and retention of lead. Lead also causes decreases in clutch and egg size, mortality of embryos and nestlings, depression of growth, and deficits in behavior that affect survival. Lead decreases migratory behavior, and increases vulnerability to cold stress, hunters, and other predators. Research needs for evaluating the risk of lead in birds include obtaining data on (1) metal dynamics within various tissues as a function of dose and time since initial exposure, (2) low-level effects on embryos, (3) effects on chicks following fledging and in the period prior to recruitment, (4) effects on adult foraging skills and reproductive behavior, and (5) the relationship between effects from exposure in the laboratory and those from exposure in the wild. This latter point is extremely important, particularly if wild birds have other means of ridding the body of lead not available or less apparent to laboratory birds.

Animals↗
PubMed2004

Overview of programmes for the assessment of risks to the environment from ionising radiation and hazardous chemicals.

Within the FASSET project, a review of existing programmes for the assessment of environmental risks from radioactive or hazardous substances was carried out in order to identify appropriate aspects that could be incorporated into the FASSET framework. The review revealed a number of different approaches, arising from the need to balance the information value of the assessment against the availability of data and the need to keep the assessment manageable. Most of the existing assessment programmes fit into a three-phase approach to environmental risk assessment: problem formulation, assessment and risk characterisation. However, the emphasis on particular assessment phases varies between programmes. The main differences between the different programmes are: the degree of specificity to a particular site, the level of detail of the assessment, the point at which a comparison is made between a criterion intended to represent 'what is acceptable' and a measured or predicted quantity, the choice of end-point for the assessment and the relationship between measurement end-points and assessment end-points. The existing assessment programmes are based on a similar general structure, which is suitable for use as a basis for the FASSET framework. However, certain aspects of the assessment of exposure and effects of ionising contaminants, e.g. dosimetry, require further development before incorporation into such a framework.

Animals↗
PubMed1997

Robust proofs of NP-hardness for protein folding: general lattices and energy potentials.

This paper addresses the robustness of intractability arguments for simplified models of protein folding that use lattices to discretize the space of conformations that a protein can assume. We present two generalized NP-hardness results. The first concerns the intractability of protein folding independent of the lattice used to define the discrete protein-folding model. We consider a previously studied model and prove that for any reasonable lattice the protein-structure prediction problem is NP-hard. The second hardness result concerns the intractability of protein folding for a class of energy formulas that contains a broad range of mean force potentials whose form is similar to commonly used pair potentials (e.g., the Lennard-Jones potential). We prove that protein-structure prediction is NP-hard for any energy formula in this class. These are the first robust intractability results that identify sources of computational complexity of protein-structure prediction that transcend particular problem formulations.

Models, Chemical↗
PubMed1985

An appraisal of goals for residency training in internal medicine.

The goals for residency training in internal medicine were assessed by faculty and house staff members at one university-based program using a 38-item questionnaire based largely upon American Board of Internal Medicine criteria. The respondents rated each item according to its ideal importance, its actual emphasis in training, and the respondents' degree of satisfaction with their own level of accomplishment for that item. Faculty and house staff members shared similar perceptions of ideal goals and actual emphases of training, with both groups rating clinical judgment, gathering data, and formulating problems as the most important. Both groups also tended to rate highly as ideal goals those items that they considered to be their own professional strengths and that reflected their current respective roles in medical training. This trend was the most apparent for faculty members in ratings of academic skills and for house staff members in ratings of technical proficiency and patient management skills. The tendency to idealize one's own professional role and strengths may inhibit needed changes in residency training.

Clinical Competence↗
PubMed1991

Clinical behaviors and skills that faculty from 12 institutions judged were essential for medical students to acquire.

This paper describes a 1988-1989 collaborative mail survey of faculty opinion about clinical behaviors and skills that students should be expected to demonstrate prior to graduation from undergraduate medical school (hereafter called "exit objectives"). Selected faculty from 12 American and Canadian medical schools indicated whether each of 77 objectives was essential for every student to know or demonstrate prior to graduation; useful but not essential at the undergraduate level; or not applicable to their undergraduate program. Their responses provide a glimpse into faculty expectations regarding some of the exit behaviours and skills they deemed essential. Forty-two percent (32) of the 77 objectives were regarded as essential by 75% or more of the faculty members who responded. Essential objectives involved conducting organ system examinations, formulating problems and hypotheses, and gathering fundamental interview, physical, and screening examination data, including emergency examinations of the airway and circulatory systems. Other essential objectives involved collaboration and communication, demonstrating concern for legal and ethical values, and keeping abreast of current information within the discipline. Exit objectives related to the diagnosis and management of specific conditions were regarded as useful but not essential at the undergraduate level. Implications for medical education are discussed.

Canada↗
PubMed1979

Automated medical screening in an urban county jail.

A machine-administered, branch-chain automated medical history (AMH) was evaluated as a medical intake screening tool for inmates of a large metropolitan county jail. The reproducibility, validity, sensitivity and specificity of the AMH were measured and found comparable to other previously reported AMH systems. The AMH did not produce intake screening data comparable to that obtained by trained face to face medical interviewers. This, in addition to the time and personnel effort required for administering the AMH while preventing vandalization of the equipment, made the AMH impractical for use in the county jail setting. Physicians used only 21 per cent of the positive AMH responses when they were asked to formulate problem lists from the AMH data. Physicians who used the AMH in clinical settings complained that "the AMH data seem as often wrong as right." The authors observed that the number of true-positive AMH responses was matched by an almost equal number of false-positve and false-negative responses. This may account for the physician's subjective response. If so, this represents a problem to be addressed by future AMH systems. Physicians used only 55.8 per cent of the intake screening information obtained by nurse practitioners. This was also somewhat lower than expected. For this reason, medical historical information in the county jail setting might be most efficiently obtained by the provider who has clinical responsibility for prescribing treatment.

Attitude of Health Personnel↗
PubMed2003

Tokamak equilibria with reversed current density.

Observations of nearly zero toroidal current in the central region of tokamaks (the "current hole") raises the question of the existence of toroidal equilibria with very low or reversed current in the core. The solutions of the Grad-Shafranov equilibrium equation with hollow toroidal current density profile including negative current density in the plasma center are investigated. Solutions of the corresponding eigenvalue problem provide simple examples of such equilibrium configurations. More realistic equilibria with toroidal current density reversal are computed using a new equilibrium problem formulation and computational algorithm which do not assume nested magnetic surfaces.

Journal Article↗
PubMedDate not supplied

A powerful approach for effective finding of significantly differentially expressed genes.

The problem of identifying significantly differentially expressed genes for replicated microarray experiments is accepted as significant and has been tackled by several researchers. Patterns from Gene Expression (PaGE) and q-values are two of the well-known approaches developed to handle this problem. This paper proposes a powerful approach to handle this problem. We first propose a method for estimating the prior probabilities used in the first version of the PaGE algorithm. This way, the problem definition of PaGE stays intact and we just estimate the needed prior probabilities. Our estimation method is similar to Storey's estimator without being its direct extension. Then, we modify the problem formulation to find significantly differentially expressed genes and present an efficient method for finding them. This formulation increases the power by directly incorporating Storey's estimator. We report the preliminary results on the BRCA data set to demonstrate the applicability and effectiveness of our approach.

Algorithms↗
PubMed2005

A soft double regularization approach to parametric blind image deconvolution.

This paper proposes a blind image deconvolution scheme based on soft integration of parametric blur structures. Conventional blind image deconvolution methods encounter a difficult dilemma of either imposing stringent and inflexible preconditions on the problem formulation or experiencing poor restoration results due to lack of information. This paper attempts to address this issue by assessing the relevance of parametric blur information, and incorporating the knowledge into the parametric double regularization (PDR) scheme. The PDR method assumes that the actual blur satisfies up to a certain degree of parametric structure, as there are many well-known parametric blurs in practical applications. Further, it can be tailored flexibly to include other blur types if some prior parametric knowledge of the blur is available. A manifold soft parametric modeling technique is proposed to generate the blur manifolds, and estimate the fuzzy blur structure. The PDR scheme involves the development of the meaningful cost function, the estimation of blur support and structure, and the optimization of the cost function. Experimental results show that it is effective in restoring degraded images under different environments.

Algorithms↗