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At least 235 records · Page 13Linked to original sources
PubMed1995

An excitation-pattern model for the starling (Sturnus vulgaris).

This paper develops and tests an excitation-pattern model for the starling. Like excitation-pattern models for humans [e.g., Zwicker, Acustica 6, 365-381 (1956); Florentine and Buus, J. Acoust. Soc. Am. 70, 1646-1654 (1981)], the model for starlings provides a unified account of a large body of data. The foundation of the model is a critical-band scale, which is derived as an equal-distance scale according to a cochlear-map function. The cochlear-map function is determined as a best-fitting function to physiological data relating characteristic frequency (CF) of auditory-nerve fibers to their place of innervation on the basilar papilla. Excitation patterns are derived from auditory-nerve measurements of levels at CF necessary to produce firing rates equal to those evoked by a test tone. The shape of these excitation patterns is independent of level and frequency when plotted on a cochlear-distance scale. The resulting model indicates that 10-dB bandwidths of auditory-nerve tuning curves and frequency DLs can be approximated as equal distances along the basilar papilla. Predictions of level discrimination are in good agreement with the data, except below 20 dB SL. Overall, the present work indicates that excitation-pattern models account for a wide range of auditory phenomena in both humans and starlings, when the models take into account differences in critical-band scales, absolute thresholds, excitation-pattern slopes, and growth of excitation, which is linear in starlings, but nonlinear in humans.

Animals↗
PubMedDate not supplied

Consumer-directed services at home: a new model for persons with disabilities.

The past decade has produced a wave of new state programs that have introduced consumer direction into home-based services for persons with chronic impairments. Building upon earlier models developed for younger adults with physical disabilities, consumer-directed models are now being adapted to recipients of all ages with federal, state, and foundation support. These models shift responsibility for key service decisions from professionals to recipients and challenge the traditional home care agency model. Research evidence on the impact of consumer direction is just becoming available to policymakers. This paper reviews what we have learned from program and research activity so far, and what key issues and challenges remain.

Case Management↗
PubMedDate not supplied

The Pfizer Foundation's Community Health Ventures program: providing models for community health partnerships.

In response to its concern for the future of community health centers (CHCs) and those who receive care in these centers, in 1997 the Pfizer Foundation created and funded Community Health Ventures (CHV), a four-year, $3.6 million grant-making program. It was designed to increase the capacity of centers to adjust to a changing health care environment. This descriptive special report discusses the outcomes of the program, including its impact on CHCs and their patients, and offers recommendations for funders on how to establish effective partnerships with CHCs.

Chronic Disease↗
PubMed2004

Low-dose hyper-radiosensitivity: a consequence of ineffective cell cycle arrest of radiation-damaged G2-phase cells.

This review highlights the phenomenon of low-dose hyper- radiosensitivity (HRS), an effect in which cells die from excessive sensitivity to small single doses of ionizing radiation but become more resistant (per unit dose) to larger single doses. Established and new data pertaining to HRS are discussed with respect to its possible underlying molecular mechanisms. To explain HRS, a three-component model is proposed that consists of damage recognition, signal transduction and damage repair. The foundation of the model is a rapidly occurring dose-dependent pre-mitotic cell cycle checkpoint that is specific to cells irradiated in the G2phase. This checkpoint exhibits a dose expression profile that is identical to the cell survival pattern that characterizes HRS and is probably the key control element of low-dose radiosensitivity. This premise is strengthened by the recent observation coupling low- dose radiosensitivity of G2-phase cells directly to HRS. The putative role of known damage response factors such as ATM, PARP, H2AX, 53BP1 and HDAC4 is also included within the framework of the HRS model.

Adaptation, Physiological↗
PubMed1989

Physiological pharmacokinetic model of adriamycin delivered via magnetic albumin microspheres in the rat.

The influence of magnetic albumin microspheres on the disposition of adriamycin was evaluated. Adriamycin concentrations were monitored in multiple rat tissues for 48 hr after its intra-arterial administration (2 mg/kg) as a solution and associated with magnetic albumin microspheres. The magnetic dosage form was targeted to a predefined tail segment with a magnetic field strength of 8000 G applied for 30 min after dosing. A physiological pharmacokinetic model was used to describe the disposition of adriamycin following its administration from either dosage form. The model developed for the data resulting from administration of adriamycin as a solution served as a foundation for the model developed for adriamycin resulting from the administration of adriamycin associated with the magnetic dosage form. The model for adriamycin following administration of the magnetic microspheres required additional relationships to describe the transport of adriamycin associated with the microspheres. For both models, the predicted adriamycin concentrations were in adequate agreement with the observed values. The present investigation demonstrates the use of a physiological pharmacokinetic modeling method to represent drug kinetics following its administration via a targeted drug delivery system.

Albumins↗
PubMed2003

Comparison of the genomes of human and mouse lays the foundation of genome zoology.

The extensive similarities between the genomes of human and model organisms are the foundation of much of modern biology, with model organism experimentation permitting valuable insights into biological function and the aetiology of human disease. In contrast, differences among genomes have received less attention. Yet these can be expected to govern the physiological and morphological distinctions apparent among species, especially if such differences are the result of evolutionary adaptation. A recent comparison of the draft sequences of mouse and human genomes has shed light on the selective forces that have predominated in their recent evolutionary histories. In particular, mouse-specific clusters of homologues associated with roles in reproduction, immunity and host defence appear to be under diversifying positive selective pressure, as indicated by high ratios of non-synonymous to synonymous substitution rates. These clusters are also frequently punctuated by homologous pseudogenes. They thus have experienced numerous gene death, as well as gene birth, events. These regions appear, therefore, to have borne the brunt of adaptive evolution that underlies physiological and behavioural innovation in mice. We predict that the availability of numerous animal genomes will give rise to a new field of genome zoology in which differences in animal physiology and ethology are illuminated by the study of genomic sequence variations.

Animals↗
PubMed1989

Teaching theories and models of nursing: implications for a common foundation programme for nurses.

At the present time nurse education is facing a number of upheavals which have major implications for curriculum development. No hard and fast rules governing the approach to educating learners about nursing theory and nursing models can be made. This paper has generated a number of suggestions which could be explored as new courses are designed and evaluated. It is the responsibility of teachers and practitioners to be aware of the changes ushered in by the implementation of Project 2000 and to seek to ensure that students are appropriately prepared for the professional demands of the years ahead.

Curriculum↗
PubMed2003

Some theoretical models and constructs generic to substance abuse prevention programs for adolescents: possible relevance and limitations for problem gambling.

For the past several years the author and his colleagues have explored the area of how social psychological constructs and theoretical models can be applied to the prevention of health threatening behaviors in adolescents. In examining the need for the development of gambling prevention programs for adolescents, it might be of value to consider the application of such constructs and theoretical models as a foundation to the development of prevention programs in this emerging problem behavior among adolescents. In order to provide perspective to the reader, the present paper reviews the history of various psychosocial models and constructs generic to programs directed at prevention of substance abuse in adolescents. A brief history of some of these models, possibly most applicable to gambling prevention programs, are presented. Social inoculation, reasoned action, planned behavior, and problem behavior theory, are among those discussed. Some deficits of these models, are also articulated. How such models may have relevance to developing programs for prevention of problem gambling in adolescents is also discussed. However, the inherent differences between gambling and more directly health threatening behaviors such as substance abuse must, of course, be seriously considered in utilizing such models. Most current gambling prevention programs have seldom been guided by theoretical models. Developers of gambling prevention programs should consider theoretical foundations, particularly since such foundations not only provide a guide for programs, but may become critical tools in evaluating their effectiveness.

Adolescent↗
PubMed2000

Cellulose and hemicellulose hydrolysis models for application to current and novel pretreatment processes.

Acids catalyze the hydrolysis of cellulose and hemicellulose to produce sugars that organisms can ferment to ethanol and other products. However, advanced low- and no-acid technologies are critical if we are to reduce bio-ethanol costs to be competitive as a pure fuel. We believe carbohydrate oligomers play a key role in explaining the performance of such hydrolysis processes and that kinetic models would help us understand their role. Various investigations have developed reaction rate expressions based on an Arrhenius temperature dependence that is first order in substrate concentration and close to first order in acid concentration. In this article, we evaluate these existing hydrolysis models with the goal of providing a foundation for a unified model that can predict performance of both current and novel pretreatment process configurations.

Biomass↗
PubMed1999

The mathematical modelling of cell kinetics in corneal epithelial wound healing.

This paper considers the comparison of experimental spatial and temporal data of mitotic rates measured during corneal epithelial wound healing (CEWH) of a rat model with the predictions of a computer modelling framework. We begin by briefly showing that previous models, used in the study of corneal epithelial wound healing speeds, are inadequate for the study of cell kinetics. We proceed to formulate a new modelling framework more suited to such a study. This framework is simulated in its simplest form, and the results from this motivate a new realisation of the modelling framework, including a caricature of age structuring. Finally, a model with a simple representation of juxtacrine signalling is considered. The final model captures many, though not all, of the trends of the experimental data. This paper thus lays a foundation for the modelling of the cell kinetics of corneal epithelial wound healing, and yields valuable insight regarding the important mechanisms a model should consider in order to reproduce the observed experimental trends.

Animals↗
PubMedDate not supplied

[Group therapy of bulimia nervosa and other related disorders].

The aim of this article is to present a brief group intervention model for the initial phase of the treatment of bulimia nervosa and other related eating disorders. The model combines elements from cognitive-behavioral and psychoeducational approaches. Along the article we will describe the theoretical foundations of the model, a review of the empirical evidence that supports it, and afterwards, the group procedure developed by us in our clinical experience. Later on, the clinical results of an uncontrolled study of a sample of patients who participated in the group will be introduced. Finally, we will discuss the scope and limitations of this experience.

Adult↗
PubMed2006

Promoting joint attention in toddlers with autism: a parent-mediated developmental model.

Joint attention, a foundational nonverbal social-communicative milestone that fails to develop naturally in autism, was promoted for three toddlers with early-identified autism through a parent-mediated, developmentally grounded, researcher-guided intervention model. A multiple baseline design compared child performance across four phases of intervention: focusing on faces, turn-taking, responding to joint attention, and initiating joint attention. All toddlers improved performance and two showed repeated engagement in joint attention, supporting the effectiveness of developmentally appropriate methods that build on the parent-child relationship. A complementary qualitative analysis explored family challenges, parent resilience, and variables that may have influenced outcomes. Intervention models appropriate for toddlers with autism are needed as improved early identification efforts bring younger children into early intervention services.

Attention↗
PubMedDate not supplied

Is low-dose hyper-radiosensitivity a measure of G2-phase cell radiosensitivity?

Low-dose hyper-radiosensitivity describes a phenomenon by which cells die from excessive sensitivity to small single doses of ionizing radiation below approximately 20-30 cGy. This review describes experimental data that strongly imply that low-dose hyper-radiosensitivity is exclusively associated with the survival response of cells in the G2 phase of the cycle. This G2-centric concept arose when the characteristic cell survival pattern that denotes low-dose hyper-radiosensitivity was not detected in the radiation survival response of cell populations enriched in G1 or S phase cells. In contrast, an extended or exaggerated low-dose hyper-radiosensitivity response was evident from populations selected to contain only G2 phase cells by flow cytometry cell sorting. The historical data that has defined the field of low-dose hyper-radiosensitivity will be considered with respect to the radiation sensitivity of, and cell cycle checkpoints specific to, G2 phase cells. A working model of the putative mechanism of low-dose hyper-radiosensitivity will be presented within this context. The foundation of the model is a rapidly occurring dose-dependent pre-mitotic cell-cycle checkpoint that is specific to cells irradiated in the G2 phase. This early G2 phase checkpoint has been demonstrated to exhibit a dose expression profile that is comparable to the cell-survival pattern that defines low-dose hyper-radiosensitivity and is therefore a likely key regulator of the phenomenon.

Animals↗
PubMed1984

Psychosexual development: a model for teaching nursing intervention.

This model is an attempt to meaningfully reduce psychosexual development to its essential elements in order to facilitate learning, and, ultimately, the development of nursing interventions that are evolved from a theoretical base, produced out of a wholistic view of psychosexual development and arise from a conception of sexuality as a healthy, normal phenomenon. It certainly possesses limitations. No model can replace the nurse-client relationship upon which knowledge and insight into the client's unique character and needs are based. However, utilizing a model as a foundation for learning and nursing practice can become the first step in determining successful client service. Using a psychosexual development model in concert with our overall view of human beings serves to strengthen our commitment to treating individuals as integrated wholes. "Human sexuality, that dimension of maleness and femaleness in one's personality, is expressed in every human act; it is inseparable from the maintenance of one's health" (Jacobson, 1974).

Adolescent↗
PubMed2006

Theoretical foundation to estimate the relative efficiencies of the Jukes-Cantor+gamma model and the Jukes-Cantor model in obtaining the correct phylogenetic tree.

This paper deals with the theoretical foundation to estimate the relative efficiency (probability of inferring the true tree) of different nucleotide substitution models. A novel theoretical approach has been developed to estimate the relative efficiency of nucleotide substitution models based on the neighbor-relation method. The theory was developed directly by using the four-point condition. Initially theoretical formulas for the Jukes-Cantor+gamma (JC+Gamma) model and the Jukes-Cantor (JC) model were developed to estimate their relative efficiencies. Theoretical formulas were used on several model topologies for both models to obtain a true tree. Extensive simulations were performed on the same set of trees to test the strength of the theoretical approach. Simulation results demonstrated a good agreement with results obtained by the theoretical estimation. Overall the theoretical foundation for estimating model efficiencies is very accurate.

Algorithms↗
PubMed2000

Can cultural competency reduce racial and ethnic health disparities? A review and conceptual model.

This article develops a conceptual model of cultural competency's potential to reduce racial and ethnic health disparities, using the cultural competency and disparities literature to lay the foundation for the model and inform assessments of its validity. The authors identify nine major cultural competency techniques: interpreter services, recruitment and retention policies, training, coordinating with traditional healers, use of community health workers, culturally competent health promotion, including family/community members, immersion into another culture, and administrative and organizational accommodations. The conceptual model shows how these techniques could theoretically improve the ability of health systems and their clinicians to deliver appropriate services to diverse populations, thereby improving outcomes and reducing disparities. The authors conclude that while there is substantial research evidence to suggest that cultural competency should in fact work, health systems have little evidence about which cultural competency techniques are effective and less evidence on when and how to implement them properly.

Acculturation↗
PubMed2003

A path-analytic strategy to analyze psychoanalytic treatment effects.

This paper introduces a path-analytic strategy to analyze psychoanalytic treatment effects. A simple causal model is used to analyze a well-known case study by Charles Brenner. Application of even this simple model to the case study sharpens causal inferences that may be validly made, highlights important aspects of the psychoanalytic process and builds a foundation for further model development.

Adult↗