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At least 811 records · Page 45Linked to original sources
PubMed2004

Random drift and large shifts in popularity of dog breeds.

A simple model of random copying among individuals, similar to the population genetic model of random drift, can predict the variability in the popularity of cultural variants. Here, we show that random drift also explains a biologically relevant cultural phenomenon--changes in the distributions of popularity of dog breeds in the United States in each of the past 50 years. There are, however, interesting deviations from the model that involve large changes in the popularity of certain breeds. By identifying meaningful departures from our null model, we show how it can serve as a foundation for studying culture change quantitatively, using the tools of population genetics.

Animals↗
PubMed2004

Mentoring new social work faculty:a gerontological perspective.

The John A. Hartford Foundation, in collaboration with the Gerontological Society of America, has developed new models to create geriatric faculty capacity within social work. The Faculty Scholars Program is building faculty leadership in academic geriatric social work through a strategic approach that includes long-distance national and institution- based mentoring. While mentoring models have proven to be effective means of career development, this is relatively new in academic social work and little is known about the impact of long-distance mentoring in association with sponsorship from a mentor at the scholar's home institution. This paper describes the mentoring model and its conceptual underpinnings. Evaluation data from an ongoing evaluation is presented in discussion of the strengths and limitations of the mentoring model.

Aged↗
PubMed1987

Fund-raising strategies for the allied health professions.

Academic units of allied health (eg, schools and colleges of allied health) are relatively new to institutions of higher education. As a result, the academic units lack prestige with private funding sources. This article describes a development model for raising private contributions emphasizing allied health academic units. The roles of the academic department, development advisory committee, and faculty in developing the mission statement, needs, objectives, and case statement for the department are described. How the department chairperson, faculty, dean, and advisory committee members interact with the staff from a development office in identifying, cultivating, and soliciting private support are explained.

Allied Health Personnel↗
PubMed1996

Construction of a model demonstrating neural pathways and reflex arcs.

Employment opportunities in the future will require higher skills and an understanding of mathematics and science. As a result of the growing number of careers that require solid science and mathematics training, the methods of science education are undergoing major reform. To adequately equip students for technologically advanced positions, new teaching methods must be developed that prepare tomorrow's workforce for the challenges of the 21st century. One such method is the use of models. By actively building and manipulating concrete models that represent scientific concepts, students are involved in the most basic level of Piaget's learning scheme: the sensorimotor stage. Models are useful in reaching all students at the foundational levels of learning, and further learning experiences are rapidly moved through higher learning levels. This success ensures greater comprehension and understanding compared with the traditional methods of rote memorization. We developed an exercise for the construction of an inexpensive, easy-to-build model demonstrating neural pathways and reflex arcs. Our exercise also includes many supplemental teaching tools. The exercise is designed to fulfill the need of sound physiological teaching materials for high school students.

Animals↗
PubMed2005

Predictive, non-GLP models of secondary pharmacodynamics: putting the best compounds forward.

Secondary pharmacodynamic studies of new chemical entities (NCEs) play a critical role in support of efficient drug discovery. In an era in which speed and efficiency are the norm for pharmaceutical discovery, the need to identify NCEs with greater patient tolerability continues to increase. Early use of secondary pharmacodynamic models (in vivo and in vitro) provides the foundation for critical, early decisions regarding lead molecules. Scientifically robust, non-GLP (good laboratory practices) secondary pharmacodynamic studies can eliminate compounds or structural series with undesirable profiles early, and may prove useful in defining structure-activity relationships (SARs) with regards to off-target effects.

Animals↗
PubMed2006

Optimal phasic tracheal gas insufflation timing: an experimental and mathematical analysis.

OBJECTIVE: To investigate the modulation of CO2 clearance by changes in the duration of tracheal gas flow application during tracheal gas insufflation (TGI). DESIGN: Combination of bench studies using a commercial test lung and a commercially available intensive care ventilator and mathematical analysis using a clearance model derived from first principles. SETTING: University pulmonary research laboratory. PATIENTS: None. INTERVENTIONS: Experiments using TGI were performed on a test lung at two combinations of tidal volume and frequency. TGI was limited to part of the expiratory phase (the terminal 10-100% of expiration), and two different TGI catheter flow rates were studied. Permutations over a range of compliances, dead-space volumes, catheter flows, and TGI durations were collected. A mathematical model incorporating key ventilatory and TGI-related variables was developed to provide a first-principles theoretical foundation for interpreting the experimental results. MEASUREMENTS AND MAIN RESULTS: In the physical model, alveolar Pco2 attained a minimum value with TGI flow applied during the terminal 40-60% of the expiratory phase, a finding that was consistent over an almost eight-fold range of expiratory time constants. The mathematical model shows the same qualitative pattern as the experimental model, indicating that the observed behaviors are not an experimental artifact. CONCLUSION: The optimal duration of expiratory TGI flow application is stable over a wide range of impedance characteristics. Such stability suggests that near maximal effect of expiratory TGI could be obtained by applying TGI flow solely within the final 50% of the expiratory phase. Such uniform restriction of the application profile might both simplify technique implementation and decrease adverse consequences.

Carbon Dioxide↗
PubMedDate not supplied

A logical foundation for representation of clinical data.

OBJECTIVE: A general framework for representation of clinical data that provides a declarative semantics of terms and that allows developers to define explicitly the relationships among both terms and combinations of terms. DESIGN: Use of conceptual graphs as a standard representation of logic and of an existing standardized vocabulary, the Systematized Nomenclature of Medicine (SNOMED International), for lexical elements. Concepts such as time, anatomy, and uncertainty must be modeled explicitly in a way that allows relation of these foundational concepts to surface-level clinical descriptions in a uniform manner. RESULTS: The proposed framework was used to model a simple radiology report, which included temporal references. CONCLUSION: Formal logic provides a framework for formalizing the representation of medical concepts. Actual implementations will be required to evaluate the practicality of this approach.

Computer Simulation↗
PubMed2002

Mathematical modelling in the post-genome era: understanding genome expression and regulation--a system theoretic approach.

This paper introduces a mathematical framework for modelling genome expression and regulation. Starting with a philosophical foundation, causation is identified as the principle of explanation of change in the realm of matter. Causation is, therefore, a relationship, not between components, but between changes of states of a system. We subsequently view genome expression (formerly known as 'gene expression') as a dynamic process and model aspects of it as dynamic systems using methodologies developed within the areas of systems and control theory. We begin with the possibly most abstract but general formulation in the setting of category theory. The class of models realised are state-space models, input--output models, autoregressive models or automata. We find that a number of proposed 'gene network' models are, therefore, included in the framework presented here. The conceptual framework that integrates all of these models defines a dynamic system as a family of expression profiles. It becomes apparent that the concept of a 'gene' is less appropriate when considering mathematical models of genome expression and regulation. The main claim of this paper is that we should treat (model) the organisation and regulation of genetic pathways as what they are: dynamic systems. Microarray technology allows us to generate large sets of time series data and is, therefore, discussed with regard to its use in mathematical modelling of gene expression and regulation.

Gene Expression↗
PubMedDate not supplied

Homeostasis: a framework for integrating the life sciences.

Nurse education curricula continue to emphasize the holistic nature of health and ill-health. As a concept, holism recognizes that the interactions between a person and his/her environment are significant factors in shaping the individual, and important determinants of wellbeing. Psychosocial interactions as a basis for health now figure prominently in nursing curricula. In contrast, the applied biological sciences have increasingly become marginalized, yet knowledge of the biological construct of the individual, and an understanding of how it is influenced by psychosocial interactions, are also necessary if holistic care is the aim. Nursing models attempt to reinforce holistic principles, but the integrative nature of health and illness needs to be established before their application. This article proposes that the concept of homeostasis, and its relationship to systems theory, provides a workable framework for teaching the basis of health, and so forms a foundation for the application of nursing theory and nursing models.

Biological Science Disciplines↗
PubMed1997

The two cultures and the health care revolution. Commerce and professionalism in medical care.

The current trend toward the invasion of commerce into medical care, an arena formerly under the exclusive purview of physicians, is seen by the authors as an epic clash of cultures between commercial and professional traditions in the United States. Both have contributed to US society for centuries; both have much to offer in strengthening medical care and reducing costs. At the same time, this invasion by commercialism of an arena formerly governed by professionalism poses severe hazards to the care of the sick and the welfare of communities: the health of the public and the public health. Some of these hazards are briefly listed and reviewed, together with a brief outline of standards that might be established nationally to abate these hazards. A national agency in the private sector is proposed, the National Council on Medical Care, to set standards and provide an approval mechanism that would then be the basis for state enforcement through licensing. Two models for such an initiative are outlined, one based on the National Academy of Sciences as the initiating force, and the other on an initiative provided by a consortium of national charitable foundations interested in health policy. In both cases, wide support from the national foundations would be essential. In the case of the academy model, some government funds might also be available without loss of the freedom of a private-sector initiative. Some operational options for such a national council, its membership, and the conduct of its affairs are briefly outlined as a basis for further discussion.

Accreditation↗
PubMed2006

Achieving health equity in America.

Health disparities are both real and deadly, but disparities are not inevitable. The causes of health disparities are complex, and their elimination will require multi-dimensional interventions. We have developed a three-dimensional model for the elimination of health disparities. The foundation of public health is surveillance, which is the first dimension. We must continually measure racial-ethnic disparities in each specific disease, in its risk factors, and in outcome-relevant quality of care. The second dimension is research into the causes of disparities and potential intervention points to eliminate disparities. These causes and potential intervention points can be in the individual's biology or their behavior, or in their physical and social environment, or in the healthcare arena (quality and access). The third dimension is intervention, which requires moving from what we know to what we do. Translation must not only take knowledge from the bedside, but to the curbside and the countryside, into each community and into each home. We can achieve health equity in America, but first, we all must care enough, know enough, do enough, and persist long enough.

Cultural Characteristics↗
PubMed2004

Mathematical model of cylindrical form tolerance.

Tolerance is essential for integration of CAD and CAM. Unfortunately, the meaning of tolerances in the national standard is expressed in graphical and language forms and is not adaptable for expression, processing and data transferring with computers. How to interpret its semantics is becoming a focus of relevant studies. This work based on the mathematical definition of form tolerance in ANSI Y14.5.1M-1994, established the mathematical model of form tolerance for cylindrical feature. First, each tolerance in the national standard was established by vector equation. Then on the foundation of tolerance's mathematical definition theory, each tolerance zone's mathematical model was established by inequality based on degrees of feature. At last the variance area of each tolerance zone is derived. This model can interpret the semantics of form tolerance exactly and completely.

Algorithms↗
PubMed1999

Otitis media: the chinchilla model.

Streptococcus pneumoniae infection and disease have been modeled in several animal species including infant and adult mice, infant and adult rats, infant Rhesus monkeys, and adolescent and adult chinchillas. Most are models of sepsis arising from intravenous or intraperitoneal inoculation of bacteria, and a few were designed to study disease arising from intranasal infection. Chinchillas provide the only animal model of middle ear pneumococcal infection in which the disease can be produced by very small inocula injected into the middle ear (ME) or intranasally, and in which the disease remains localized to the ME in most cases. This model, developed at the University of Minnesota in 1975, has been used to study pneumococcal pathogenesis at a mucosal site, immunogenicity and efficacy of pneumococcal capsular polysaccharide (PS) vaccine antigens, and the kinetics and efficacy of antimicrobial drugs. Pathogenesis experiments in the chinchilla model have revealed variation in ME virulence among different pneumococcal serotypes, enhancement of ME infection during concurrent intranasal influenza A virus infections, and natural resolution of pneumococcal otitis media (OM) without intervention. Research has explored the relative contribution of pneumococcal and host products to ME inflammation. Pneumococcal cell wall components and pneumolysin have been studied in the model. Host inflammatory responses studied in the chinchilla ME include polymorphonuclear leukocyte oxidative products, hydrolytic enzymes, cytokine and eicosanoid metabolites, and ME epithelial cell adhesion and mucous glycoprotein production. Both clinical (tympanic membrane appearance) and histopathology (ME, Eustachian tube, inner ear) endpoints can be quantified. Immunologic and inflammatory studies have been facilitated by the production of affinity-purified antichinchilla immunoglobulin G (IgG), IgM, and secretory IgA polyclonal antibody reagents, and the identification of cross-reactivity between human and chinchilla cytokines, and between guinea pig and chinchilla C3. Alteration of ME mucosa by pneumococcal neuraminidase and alteration of ME epithelial cell (MEEC) surface carbohydrates during intranasal pneumococcal infection have been demonstrated. Pathogenesis studies have been aided by cultured chinchilla MEEC systems, in which the ability of platelet activating factor and interleukin (IL)-1 beta to stimulate epithelial mucous glycoprotein synthesis has recently been demonstrated. Because chronic OM with effusion is characterized by presence of large amounts of mucous glycoprotein in the ME, pneumococcus may have an important role in both acute and chronic ME disease. Both unconjugated PS and PS-protein-conjugated vaccines are immunogenic after intramuscular administration without adjuvant in chinchillas. Passive protection studies with human hyperimmune immunoglobulin demonstrated that anti-PS IgG alone is capable of protecting the chinchilla ME from direct ME challenge with pneumococci. Active PS immunization studies demonstrated protection following direct ME and intranasal pneumococcal challenge with and without concurrent influenza A virus infection. An attenuated influenza A virus vaccine also showed protection for pneumococcal OM. Antimicrobial treatment of acute OM has been based almost exclusively on empirical drug use and clinical trials without a foundation of ME pharmacokinetics. Studies in the chinchilla model have started to bring a rational basis to drug selection and dosing. Microassays have been developed using high-pressure liquid chromatography for many relevant drugs. Studies have explored the in vivo ME response in pneumococcal OM to antimicrobial drugs at supra- and sub-minimum inhibitory concentration (MIC), the effect of concurrent influenza A virus infection on ME drug penetration, and the effect of treatment on sensorineural hearing loss produced by pneumococcal OM.

Animals↗
PubMed1997

Ways of knowing about health: an aboriginal perspective.

Because of the questionable applicability to extant health promotion models and middle-range theories to aboriginal peoples, foundational inquiries examining the nature of cultural beliefs and ways of knowing about health within the cultures of various ethnic groups are imperative. This article describes the ways of knowing about health reported by Ojibwe people during an ethnographic inquiry in the Great Lakes region. These ways included stories from the oral tradition, authoritative knowledge of elders, "commonsense" models of illness and health, spiritual knowledge, and knowing oneself. The health-world view, a conceptual orientation for investigating health beliefs, is offered.

Attitude to Health↗
PubMed2002

Max Eitingon and the struggle to establish an international standard for psychoanalytic training (1925-1929).

This paper deals with the first years of the IPA's International Training Commission (ITC). The author begins by outlining the Berlin model of training, including some less familiar aspects, and he describes how the foundation of the ITC in 1925 was designed for promoting the general establishment of institutionalised training according to this pioneer model. In relation to lay analysis, he highlights the issue of central power versus local autonomy with regard to admission policy. The latter part of the narrative is devoted to an ITC subcommittee ("Eitingon Committee"), appointed in 1927, which tried to formulate training guidelines for the whole IPA, again with a clear Berlin profile. The discussion of the draft of these guidelines among all branch societies (with Freud himself participating) revealed some interesting disagreements, while the "closed" nature of the system, as opposed to what later came to be called an "open system", was hardly challenged. The initiative failed, apparently through American opposition, but essentially because of the developmental gap between local societies as to the institution of specialised psychoanalytic training. The paper is based largely on unpublished material and also provides some information about Max Eitingon, the least well known of the early leaders of psychoanalysis.

History, 20th Century↗
PubMed1997

Realized versus expected gains in milk and fat production of Holstein cattle, considering the effects of days open.

The objective of this study was to determine whether differences in first lactation production, unadjusted or adjusted for days open, were correctly predicted by pedigree estimates for two lines of Holstein cattle. Data on 875 cows from two selection lines were collected from 1970 to 1988. Lines were created by mating foundation females of high or low pedigree merit to sires selected for high or average PTA milk. Both lines were managed identically to minimize environmental differences. The number of days open was analyzed with a fixed effects model containing year, season, interaction of year and season, sire line, foundation group, and interaction of sire line and foundation groups. The high milk line had significantly more days open than did the average line. Adjusted and unadjusted records for milk and fat were analyzed with the model described previously, plus the interaction of sire line and year. Least squares means and estimates for mean parent average were used to calculate realized and expected differences in production between lines within and across years. Adjustment of records for days open reduced estimates of realized gain, but not significantly. Regressions of realized gain on expected gain indicated that expected gains were matched or exceeded by unadjusted or adjusted realized gain.

Animals↗
PubMed2005

Prediction of two-phase capillary pressure-saturation relationships in fractional wettability systems.

Capillary pressure/saturation data are often difficult and time consuming to measure, particularly for non-water-wetting porous media. Few capillary pressure/saturation predictive models, however, have been developed or verified for the range of wettability conditions that may be encountered in the natural subsurface. This work presents a new two-phase capillary pressure/saturation model for application to the prediction of primary drainage and imbibition relations in fractional wettability media. This new model is based upon an extension of Leverett scaling theory. Analysis of a series of DNAPL/water experiments, conducted for a number of water/intermediate and water/organic fractional wettability systems, reveals that previous models fail to predict observed behavior. The new Leverett-Cassie model, however, is demonstrated to provide good representations of these data, as well as those from two earlier fractional wettability studies. The Leverett-Cassie model holds promise for field application, based upon its foundation in fundamental scaling principles, its requirement for relatively few and physically based input parameters, and its applicability to a broad range of wetting conditions.

Environmental Pollutants↗
PubMed2004

A comparative study of two modeling approaches in neural networks.

The neuron state modeling and the local field modeling provides two fundamental modeling approaches to neural network research, based on which a neural network system can be called either as a static neural network model or as a local field neural network model. These two models are theoretically compared in terms of their trajectory transformation property, equilibrium correspondence property, nontrivial attractive manifold property, global convergence as well as stability in many different senses. The comparison reveals an important stability invariance property of the two models in the sense that the stability (in any sense) of the static model is equivalent to that of a subsystem deduced from the local field model when restricted to a specific manifold. Such stability invariance property lays a sound theoretical foundation of validity of a useful, cross-fertilization type stability analysis methodology for various neural network models.

Algorithms↗