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PubMed1988

Identifying features, performance, and limitations of dairy ration formulation software: a comparison of three ration formulation programs.

A method for evaluating and selecting dairy ration formulation software for microcomputers is presented. Information obtained from a survey of practicing nutritionists and from interviews with computer programmers was used to identify users' needs, desired features, and patterns of use. A benchmark problem consisting of 15 activities frequently required in designing dairy rations was developed to evaluate ease of use, ease of learning, and software performance. Ease of use was measured by counting keystrokes and recording time required by a user familiar with these ration formulation programs to complete the benchmark problem. Ease of learning was measured as the amount of help and time needed by users unfamiliar with this software to complete the benchmark problem. Software performance was measured by speed of formulation, ration costs, ingredients and amounts selected, and nutrient content of rations. Evaluation of three commercially available software applications was made using the method developed.

Animal Feed↗
PubMed1998

Redesigning metabolic networks using mathematical programming

The design of new generation bioprocessing plants is increasingly dependent on the design of process-compatible microorganisms. The latter, whether through genetic or physiological manipulations, can be greatly assisted by metabolic engineering. An emerging powerful tool in metabolic engineering research is computer-assisted cell design using mathematical programming. In this work, the problem of optimizing cellular metabolic networks has been formulated as a Mixed Integer Nonlinear Programming (MINLP) model. The model can assist genetic engineers to identify which cellular enzymes should be modified, and the new levels of activity required to produce an optimal network. Results are presented from the tricarboxylic acid cycle in Dictyostelium discoideum. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗
PubMed1995

Quality improvement in health care organizations: a general systems perspective.

A systems analysis of healthcare organizations demonstrates that methods for improving quality involve the effective feedback regulation of key organizational performance parameters. Information flow is impaired in dysfunctional healthcare organizations, which often disregard significant clinical problems while preferentially tracking nonclinical indicators and clinical data considered most likely to meet the organization's standards. Such organizations thus achieve "pseudocompliance" with external requirements, but do not systematically work to improve the quality of clinical care or their performance as organizations. Efforts by government agencies and national organizations to foster quality improvement activities have had limited success precisely because local organizations perceive these efforts as externally imposed. Leaders' anxieties about their own and their organizations' autonomy, control, and performance can cause unwillingness to review data indicating performance problems, oversimplification of decision criteria, and reluctance to formulate meaningful conclusions and act on them. Contemporary quality improvement models, such as Continuous Quality Improvement (CQI) and Total Quality Management (TQM), reconnect leaders to their organizations' quality processes by emphasizing the leaders' roles in promoting quality as an organizational value, setting meaningful quality goals, and actively u sing information to improve organizational effectiveness.

Delivery of Health Care↗
PubMed1976

NMR analysis of pharmaceuticals XIV: determination of amyl nitrite in its inhalant dosage form.

An NMR procedure is described for the analysis of amyl nitrite as a drug entity and in inhalant dosage forms. The choices of solvent (carbon tetrachloride) and internal standards (biphenyl or benzyl benzoate) were made with respect to stability problems and the presence of stabilizers in the formulation. The method is precise, with a standard deviation of +/-0.5. The NMR results of synthetic solutions and commercial preparations were compared with those obtained by a published relative NMR procedure and a compendial titrimetric method. The results were generally satisfactory.

Amyl Nitrite↗
PubMed2007

Planning and analysis of three-arm non-inferiority trials with binary endpoints.

Three-arm trials including an experimental treatment, an active control and a placebo group are frequently preferred for the assessment of non-inferiority. In contrast to two-arm non-inferiority studies, these designs allow a direct proof of efficacy of a new treatment by comparison with placebo. As a further advantage, the test problem for establishing non-inferiority can be formulated in such a way that rejection of the null hypothesis assures that a pre-defined portion of the (unknown) effect the reference shows versus placebo is preserved by the treatment under investigation. We present statistical methods for this study design and the situation of a binary outcome variable. Asymptotic test procedures are given and their actual type I error rates are calculated. Approximate sample size formulae are derived and their accuracy is discussed. Furthermore, the question of optimal allocation of the total sample size is considered. Power properties of the testing strategy including a pre-test for assay sensitivity are presented. The derived methods are illustrated by application to a clinical trial in depression.

Controlled Clinical Trials as Topic↗
PubMed1997

To treat or not to treat: the case of tuberculosis.

Incomplete treatment of patients with infectious tuberculosis (TB) may not only lead to relapse but also to the development of antibiotic resistant TB-one of the most serious health problems facing society today. In this article, we formulate one-strain and two-strain TB models to determine possible mechanisms that may allow for the survival and spread of naturally resistant strains of TB as well as antibiotic-generated resistant strains of TB. Analysis of our models shows that non-antibiotic co-existence is possible but rare for naturally resistant strains while co-existence is almost the rule for strains that result from the lack of compliance with antibiotic treatment by TB infected individuals.

Antitubercular Agents↗
PubMed1991

A disaggregation model of a flexible nurse scheduling support system.

A nurse scheduling support system is developed in which the demand profile and nurses' preferences are input to an expert-like capability designed to formulate linear and/or goal programming representations of the problem. Solutions of the alternative optimization models of this decision support system are then evaluated. An assignment model for disaggregating the optimum work patterns of individual nurses based on their desires and compatibilities is discussed in detail. A brief overview of one of the scheduling models and its extension is also presented along with discussion of the various uses of the assignment model.

Hospitals, Urban↗
PubMed1992

Enhancing bioprocess operability with generic software sensors.

This paper discusses the concept of generic model-based software sensors with particular reference to bioprocess application. The industrial need for software sensing is considered and two industrial bioprocess systems are used in order to highlight the operability problems which warrant their development. Alternative philosophies for formulation are considered and the relative merits of the methodologies discussed. In particular, two different procedures are presented--an adaptive linear model based method, and a method based upon artificial neural networks. The performances of these alternative approaches are studied by their application to two industrial demonstrator processes. The results serve to highlight the operability improvements that can be gained through software sensor development.

Biosensing Techniques↗
PubMed1989

Toxicology studies of a chemical mixture of 25 groundwater contaminants. I. Chemistry development.

As part of an effort to evaluate the toxicology of a chemically defined mixture of 25 frequently detected groundwater contaminants, we report here the formulation and analytical chemistry of this mixture. Many problems were anticipated, including limitation of solubility, chemical interactions, and extreme volatility in the aqueous solution of 25 chemicals. The final technically achievable stock solution was prepared based on EPA survey concentrations of these chemicals in groundwater around hazardous waste disposal sites, their toxicity information, and solubility of the individual compounds in the matrix of the aqueous solution of these 25 chemicals. Because the anticipated animal studies were to be conducted at various laboratories, for ease of handling and maximum stability, the stock solution was stored or shipped as two substock solutions: an organic substock with 18 neat organic chemicals in a glass vial sealed with minimum headspace and an aqueous substock solution with 6 metals of various salt forms and phenol. The concentrations of the solutions were such that direct mixing of the organic and aqueous substocks produced the desired high dose level for the animal experiments. Analyses of all 25 chemicals in the drinking water mixture required six different chromatographic and spectroscopic methods. Some loss of organic volatiles during mixing of the substocks and during the first 24 hr following preparation did occur. However, the concentrations of acetone, phenol, and all the metals remained constant during preparation. Solutions held under simulated animal cage conditions for 96 hr showed losses of the organic volatiles; the majority of which occurred within the first 24 hr. This study shows that it is possible to conduct animal experiments on an aqueous mixture containing 25 groundwater contaminants. Furthermore, a reasonable estimate of intake of individual chemicals can be achieved provided that dosing solutions are prepared fresh at frequent intervals (e.g., 48 to 72 hr) and that comprehensive analyses are carried out.

Acetone↗
PubMed1992

A critical comparison of dentifrice abrasion scores on dentine recorded by gravimetric and radiotracer methods.

Dentifrice abrasivity on dentine is conventionally ranked by various in vitro methods. The abrasivity of selected dentifrices in Switzerland was ranked in 1985 by the gravimetric and in 1989 by the radiotracer method. Because same-named brands of dentifrices were differently ranked by these methods, Swiss clinicians were unsure which ranking to follow. This paper lists the errors known to occur in both techniques, but unfortunately it is difficult to quantitate the magnitudes of these errors. Consequently, it is impossible to determine which method yields the more reliable results. Thus, researchers should look into the problem of dentifrice abrasion scores and try to formulate tests which could simplify the selection of brand-named dentifrices by clinicians and the consumers.

Densitometry↗
PubMed1994

Health of Indonesian women city-dwellers of perimenopausal age.

In the last few years more women of climacteric age, living in urban areas, have been seeking medical care. In 1989, on the invitation of 6 women's organizations in Jakarta and other cities, the Indonesian Menopause Society gave talks and held discussions in cooperation with the Department of Obstetrics and Gynaecology, Faculty of Medicine of the University of Indonesia/Dr. Cipto Mangunkusumo Hospital, Jakarta. These occasions were used to accumulate data from women participants of 40 years of age and older. The age of the respondents ranged between 40-59 years. Most were 42 years old (13.9%). Ninety-four percent were still married. Twenty-five percent had three living children. Sixty-three percent of the respondents were high school graduates who worked full time (33%), part time, or were unemployed. The average menarche age was 13 and menopausal age 50-51. Menopausal complaints were rare, hence medical consultations were rare. Tranquilizers were prescribed for those who did seek medical help. This data constitutes the basis of the formulation of a strategy to solve menopause related problems in Indonesia, where female life expectancy, and the contribution of women to society, is on the increase.

Adult↗
PubMed2006

Information systems in food safety management.

Information systems are concerned with data capture, storage, analysis and retrieval. In the context of food safety management they are vital to assist decision making in a short time frame, potentially allowing decisions to be made and practices to be actioned in real time. Databases with information on microorganisms pertinent to the identification of foodborne pathogens, response of microbial populations to the environment and characteristics of foods and processing conditions are the cornerstone of food safety management systems. Such databases find application in: Identifying pathogens in food at the genus or species level using applied systematics in automated ways. Identifying pathogens below the species level by molecular subtyping, an approach successfully applied in epidemiological investigations of foodborne disease and the basis for national surveillance programs. Predictive modelling software, such as the Pathogen Modeling Program and Growth Predictor (that took over the main functions of Food Micromodel) the raw data of which were combined as the genesis of an international web based searchable database (ComBase). Expert systems combining databases on microbial characteristics, food composition and processing information with the resulting "pattern match" indicating problems that may arise from changes in product formulation or processing conditions. Computer software packages to aid the practical application of HACCP and risk assessment and decision trees to bring logical sequences to establishing and modifying food safety management practices. In addition there are many other uses of information systems that benefit food safety more globally, including: Rapid dissemination of information on foodborne disease outbreaks via websites or list servers carrying commentary from many sources, including the press and interest groups, on the reasons for and consequences of foodborne disease incidents. Active surveillance networks allowing rapid dissemination of molecular subtyping information between public health agencies to detect foodborne outbreaks and limit the spread of human disease. Traceability of individual animals or crops from (or before) conception or germination to the consumer as an integral part of food supply chain management. Provision of high quality, online educational packages to food industry personnel otherwise precluded from access to such courses.

Consumer Product Safety↗
PubMed2004

Perianesthetic dental injuries: analysis of incident reports.

STUDY OBJECTIVE: To conduct a retrospective analysis of incident reports concerning dental injury, the most common cause for litigation against anesthesiologists, to determine specific risk factors that will help in formulating a risk reduction strategy for this clinical problem. DESIGN: Retrospective chart review of a large professional liability insurer. INTERVENTIONS: Of 40 hospitals that report to the MRM Co. as part of the professional liability insurance, during the years 1992-1999, 18 hospitals reported dental injury. A Maxillofacial surgeon (GN) and an anesthesiologist (ES), using a structured form, reviewed the reports. Evaluation of the cost of injury was determined from the patient's claims or from an evaluation of rehabilitation plan constructed by the maxillofacial surgery consultants to the company. MEASUREMENTS AND MAIN RESULTS: There were 203 incidents due to dental injury. The patients were most commonly in their 5(th) to 7(th) decade. Eighty six percent of the injured teeth were the upper incisors. Lower incisors were more likely to be injured during an urgent intubation, or due to airway manipulation other than intubation. (i.e., oral airway insertion) In only 38 (18.6%) cases was there a previous assessment of an expected difficult intubation. Dentition was judged to be pathological in 32% of the patients. CONCLUSIONS: In elective intubation, the teeth most likely to be injured are the upper incisors, in patients aged 50-70 years. In most cases dental injury is not associated with a pre-event prediction of difficult intubation.

Adolescent↗
PubMed2000

Re-design of Smith predictor systems for performance enhancement

In this paper, a new design for Smith Predictor systems is presented. It employs a deliberately mismatched model to enhance performance over a perfectly matched system while using a simple primary controller. The design methodology is formulated in the frequency domain as an optimization problem and it turns out that an approximate solution can be obtained using the linear least squares method. To improve the performance further, a modified Smith Predictor system structure is also proposed, and it reduces the system into one involving second-order dynamics for the primary controller design. Illustrative simulation of several typical processes are included.

Journal Article↗
PubMed2001

Modeling and inverse simulation of somersaults on the trampoline.

This paper describes a biomechanical model for numerical simulation of front and back somersaults, without twist, performed on the trampoline. The developed mathematical formulation is used to solve an inverse dynamics problem, in which the moments of muscle forces at the joints that result in a given (measured) motion are determined. The nature of the stunts and the way the human body is maneuvered and controlled can be studied. The calculated torques can then be used as control signals for a dynamic simulation. This provides a way to check the inverse dynamics procedures, and influence of typical control errors on somersault performance can be studied. To achieve these goals, the nonlinear dynamical model of the trampolinist and the interacting trampoline bed has been identified, and a methodology for recording the actual somersault performances was proposed. Some results of numerical simulations are reported.

Biomechanical Phenomena↗
PubMed1996

The OOPS procedure (operation on placental support): in utero airway management of the fetus with prenatally diagnosed tracheal obstruction.

Tracheal obstruction of the newborn caused by cervical masses such as teratomas and cystic hygromas can result in a profound hypoxic insult and even death, owing to an inability to establish an adequate airway after birth. Prenatal sonographic diagnosis of these congenital anomalies permits (1) anticipation of an airway problem at the time of delivery and (2) formulation of an algorithm for airway management while oxygen delivery to the baby is maintained through the placental circulation. This is the report of a fetus in whom a large anterior cervical cystic hygroma was detected by prenatal ultrasonography. A multidisciplinary management team was assembled, and an algorithm for airway management was developed. Elective cesarean delivery of the fetal head and thorax, under conditions of uterine tocolysis, permitted a controlled evaluation of the airway and endotracheal intubation while oxygen supply to the infant was maintained through the placenta. The baby remained intubated, and 2 days later underwent subtotal excision of the cervical cystic hygroma. Pharmacological maintenance of the feto-placental circulation after hysterotomy is an invaluable adjunct to airway management of the neonate with prenatally diagnosed tracheal obstruction.

Adult↗
PubMed1998

Plasmodium falciparum polyoximes: highly immunogenic synthetic vaccines constructed by chemoselective ligation of repeat B-cell epitopes and a universal T-cell epitope of CS protein.

Effective immunoprophylaxis directed against the pre-erythrocytic stages of the malaria parasite requires a vaccine that can elicit humoral and cell mediated immunity in individuals of diverse genetic background. In order for a synthetic peptide malaria vaccine to meet these requirements, problems associated with genetic restriction, peptide chemistry, adjuvant formulation and physiochemical characterization of the final synthetic vaccine product must first be overcome. To address these issues, five polyoxime vaccine candidates have been constructed by ligating purified peptide epitopes of the P. falciparum CS protein to a branched template via oxime bonds. All five constructs, including two based on templates containing the synthetic adjuvant tripalmitoyl-S-glyceryl cysteine (Pam3Cys), were of sufficient purity for characterization by mass spectrometry. The immunogenicity of the malaria polyoximes in different murine strains was compared to that of multiple antigen peptide (MAP) constructs synthesized by standard step-wise synthesis. A tri-epitope polyoxime-Pam3Cys construct, based on the repeats and a universal T-cell epitope that contains both helper and CTL epitopes of the CS protein, was shown to be a precisely-defined synthetic malaria vaccine candidate that was highly immunogenic in murine strains of diverse H-2 haplotypes.

Adjuvants, Immunologic↗
PubMed2002

A multiscale algorithm for three-dimensional free-hand ultrasound.

This paper presents a multiscale algorithm for the reconstruction of human anatomy from a set of ultrasound (US) images. Reconstruction is formulated in a Bayesian framework as an optimization problem with a large number of unknown variables. Human tissues are represented by the interpolation of coefficients associated to the nodes of a 3-D cubic grid. The convergence of the Bayesian method is usually slow and initialization dependent. In this paper, a multiscale approach is proposed to increase the convergence rate of the iterative process of volume estimation. A coarse estimate of the volume is first obtained using a cubic grid with a small number of nodes initialized with a constant value computed from the observed data. The volume estimate is then recursively improved by refining the grid step. Experimental results are provided to show that multiscale method achieves faster convergence rates compared with a single-scale approach. This is the key improvement toward real-time implementations. Experimental results of 3-D reconstruction of human anatomy are presented to assess the performance of the algorithm and comparisons with the single-scale method are presented.

Algorithms↗