New Models (new + models)

Distribution by Scientific Domains
Distribution within Medical Sciences

Selected Abstracts


Nick Bosanquet
The case for competition in healthcare has become much stronqer. Health economists have failed to notice the erosion of the old arguments for state monopoly. [source]

Ion release in patients with metal-on-metal hip bearings in total joint replacement: A comparison with metal-on-polyethylene bearings

L. Savarino
Abstract Polyethylene (PE) wear has been shown to be a problem in long-term joint replacement using metal-on-PE bearing. The use of metallic heads articulating with metallic cups could solve this problem: success will be enhanced if wear and corrosion of the articulating surfaces are maintained at a low level. New models with metal-on-metal bearing have been proposed, to be used mainly for young subjects: such coupling seems to have a reduced release, but it is unclear yet if the medium-term corrosion rate is really negligible or, on the contrary, it is significantly higher than in the metal-on-PE bearing. Aim of our study was the comparison of ion release in the serum of two groups of patients who had the same type of stable cementless prosthesis, but different bearing: twenty-six patients with metal-on-metal (Group A) and fifteen patients with metal-on-PE bearing (Group B) were examined. The follow-up was 14-38 months for group A and 18-34 months for group B. The serum concentration of chromium (Cr), cobalt (Co) and molybdenum (Mo) was measured. Twenty-two patients before surgery were used for comparison (Group C). The reference values were obtained from a population of twenty-two healthy subjects (Group D). Our findings indicate that metal-on-metal bearings produce a significantly higher systemic release of cobalt and chromium (ng/ml) when compared with levels found in metal-on-PE, pre-surgery and reference groups. Such a high release should induce to improve the bearing materials or, at least, to study the biologic fate of metal ions and consequently their long-term effects. In such a way a risk-to-benefit ratio for the patient could be established. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 467,474, 2002 [source]

Instream Flow Science For Sustainable River Management,

Geoffrey E Petts
Abstract:, Concerns for water resources have inspired research developments to determine the ecological effects of water withdrawals from rivers and flow regulation below dams, and to advance tools for determining the flows required to sustain healthy riverine ecosystems. This paper reviews the advances of this environmental flows science over the past 30 years since the introduction of the Instream Flow Incremental Methodology. Its central component, Physical HABitat SIMulation, has had a global impact, internationalizing the e-flows agenda and promoting new science. A global imperative to set e-flows, including an emerging trend to set standards at the regional scale, has led to developments of hydrological and hydraulic approaches but expert judgment remains a critical element of the complex decision-making process around water allocations. It is widely accepted that river ecosystems are dependent upon the natural variability of flow (the flow regime) that is typical of each hydro-climatic region and upon the range of habitats found within each channel type within each region. But as the sophistication of physical (hydrological and hydraulic) models has advanced emerging biological evidence to support those assumptions has been limited. Empirical studies have been important to validate instream flow recommendations but they have not generated transferable relationships because of the complex nature of biological responses to hydrological change that must be evaluated over decadal time-scales. New models are needed to incorporate our evolving knowledge of climate cycles and morphological sequences of channel development but most importantly we need long-term research involving both physical scientists and biologists to develop new models of population dynamics that will advance the biological basis for 21st Century e-flow science. [source]

Improved Design of Shearing Sections with New Calculation Models Based on 3D Finite-Element Simulations

Helmut Potente
Abstract New models for the Maddock and spiral shearing sections have been developed, employing three-dimensional finite element analysis (3D FEA). These models describe the pressure-throughput and power consumption behavior of the shearing sections for both the extrusion and the injection molding process and have been implemented in the REX 6.0 and PSI 4.0 simulation software. As a consequence it is now possible to describe the process behavior of these shearing sections within just a few seconds with the accuracy of FEA calculations. Actual Maddock shearing section (left) and actual spiral shearing section (right). [source]

A physical-mathematical model for the dispersion process in continuous mixers

H. Potente
To modify the properties of polymers, mineral fillers are frequently added during the compounding process. Because of adhesive forces, these pulverized fillers tend to agglomerate. Therefore, in order to achieve good homogenization, it is essential not only to distribute them but also to break down the solid agglomerates. A number of relating models have been published, describing observations (agglomerate rupture, erosion, clustering) made during the dispersion process in a mostly isolated manner. New models for each observed effect have been developed and later superimposed in order to get a comprehensive model of the dispersion process. To verify the model, it was implemented into a program for the process simulation of co-rotating twin-screw extruders. It was then compared to experimental data. The results showed that the model is able to describe the experimentally determined data. [source]

Devices for Noninvasive Transcranial Electrostimulation of the Brain Endorphinergic System: Application for Improvement of Human Psycho-Physiological Status

Valery P. Lebedev
Abstract: It is well known that deficit of endorphins plays an important role in disturbances of human psycho-physiological status. Previously, we revealed that brain endorphinergic structures have quasiresonance characteristics. On the basis of these data, a method of activation of the brain endorphinergic structures by means of noninvasive and rather selective transcranial electrostimulation (TES) as a kind of functional electrical stimulation (FES) was elaborated. New models of TES devices (TRANSAIR) were developed for indoor and outdoor usage. To increase the efficacy of TES, the frequency modulation according to normal distribution in the limits of the quasiresonance characteristics was put into operation. The blind and placebo-controlled (passive and active placebo) study was produced to estimate the TES effects on stress events and accompanied psycho-physiological and autonomic disturbances of different intensities on volunteers and patients in the following groups: everyday stress and fatigue; stress in regular military service and in field conditions; stress in the relatives of those lost in mass disaster; posttraumatic stress (thermal burns); and affective disorders in a postabstinence period. Some subjective verbal and nonverbal tests and objective tests (including heart rate variability) were used for estimation of the initial level of psycho-physiological status, which changes after TES sessions. It was demonstrated that fatigue, stress, and other accompanied psycho-physiological disturbances were significantly improved or abolished after 2,5 TES sessions. The TES effects were more pronounced in cases of heavier disturbances. In conclusion, activation of the brain endorphinergic structures by TES is an effective homeostatic method of FES that sufficiently improves quality of life. [source]

Does Team Midwife Care Increase Satisfaction with Antenatal, Intrapartum, and Postpartum Care?

BIRTH, Issue 3 2000
A Randomized Controlled Trial
Background:Although policymakers have suggested that improving continuity of midwifery can increase women's satisfaction with care in childbirth, evidence based on randomized controlled trials is lacking. New models of care, such as birth centers and team midwife care, try to increase the continuity of care and caregiver. The objective of this study was to evaluate the effect of a new team midwife care program in the standard clinic and hospital environment on satisfaction with antenatal, intrapartum, and postpartum care in low-risk women in early pregnancy.Methods:Women at Royal Women's Hospital in Melbourne, Australia, were randomly allocated to team midwife care (n = 495) or standard care (n = 505) at booking in early pregnancy. Doctors attended most women in standard care, and continuity of the caregiver was lacking. Satisfaction was measured by means of a postal questionnaire 2 months after the birth.Results:Team midwife care was associated with increased satisfaction, and the differences between the groups were most noticeable for antenatal care, less noticeable for intrapartum care, and least noticeable for postpartum care. The study found no differences between team midwife care and standard care in medical interventions or in women's emotional well-being 2 months after the birth.Conclusion:Conclusions about which components of team midwife care were most important to increased satisfaction with antenatal care were difficult to draw, but data suggest that satisfaction with intrapartum care was related to continuity of the caregiver. [source]

Two-dimensional Numerical Modeling Research on Continent Subduction Dynamics

WANG Zhimin
Abstract Continent subduction is one of the hot research problems in geoscience. New models presented here have been set up and two-dimensional numerical modeling research on the possibility of continental subduction has been made with the finite element software, ANSYS, based on documentary evidence and reasonable assumptions that the subduction of oceanic crust has occurred, the subduction of continental crust can take place and the process can be simplified to a discontinuous plane strain theory model. The modeling results show that it is completely possible for continental crust to be subducted to a depth of 120 km under certain circumstances and conditions. At the same time, the simulations of continental subduction under a single dynamical factor have also been made, including the pull force of the subducted oceanic lithosphere, the drag force connected with mantle convection and the push force of the mid-ocean ridge. These experiments show that the drag force connected with mantle convection is critical for continent subduction. [source]

Optimizing process allocation of parallel programs for heterogeneous clusters

Shuichi Ichikawa
Abstract The performance of a conventional parallel application is often degraded by load-imbalance on heterogeneous clusters. Although it is simple to invoke multiple processes on fast processing elements to alleviate load-imbalance, the optimal process allocation is not obvious. Kishimoto and Ichikawa presented performance models for high-performance Linpack (HPL), with which the sub-optimal configurations of heterogeneous clusters were actually estimated. Their results on HPL are encouraging, whereas their approach is not yet verified with other applications. This study presents some enhancements of Kishimoto's scheme, which are evaluated with four typical scientific applications: computational fluid dynamics (CFD), finite-element method (FEM), HPL (linear algebraic system), and fast Fourier transform (FFT). According to our experiments, our new models (NP-T models) are superior to Kishimoto's models, particularly when the non-negative least squares method is used for parameter extraction. The average errors of the derived models were 0.2% for the CFD benchmark, 2% for the FEM benchmark, 1% for HPL, and 28% for the FFT benchmark. This study also emphasizes the importance of predictability in clusters, listing practical examples derived from our study. Copyright © 2008 John Wiley & Sons, Ltd. [source]

A screen for neurotransmitter transporters expressed in the visual system of Drosophila melanogaster identifies three novel genes

Rafael Romero-Calderón
Abstract The fly eye provides an attractive substrate for genetic studies, and critical transport activities for synaptic transmission and pigment biogenesis in the insect visual system remain unknown. We therefore screened for transporters in Drosophila melanogaster that are down-regulated by genetically ablating the eye. Using a large panel of transporter specific probes on Northern blots, we identified three transcripts that are down-regulated in flies lacking eye tissue. Two of these, CG13794 and CG13795, are part of a previously unknown subfamily of putative solute carriers within the neurotransmitter transporter family. The third, CG4476, is a member of a related subfamily that includes characterized nutrient transporters expressed in the insect gut. Using imprecise excision of a nearby transposable P element, we have generated a series of deletions in the CG4476 gene. In fast phototaxis assays, CG4476 mutants show a decreased behavioral response to light, and the most severe mutant behaves as if it were blind. These data suggest an unforeseen role for the "nutrient amino acid transporter" subfamily in the nervous system, and suggest new models to study transport function using the fly eye. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007 [source]

Microanatomical diversity of the humerus and lifestyle in lissamphibians

ACTA ZOOLOGICA, Issue 2 2009
Aurore Canoville
Abstract A study of body size and the compactness profile parameters of the humerus of 37 species of lissamphibians demonstrates a relationship between lifestyle (aquatic, amphibious or terrestrial) and bone microstructure. Multiple linear regressions and variance partitioning with Phylogenetic eigenVector Regressions reveal an ecological and a phylogenetic signal in some body size and compactness profile parameters. Linear discriminant analyses segregate the various lifestyles (aquatic vs. amphibious or terrestrial) with a success rate of up to 89.2%. The models built from data on the humerus discriminate aquatic taxa relatively well from the other taxa. However, like previous models built from data on the radius of amniotes or on the femur of lissamphibians, the new models do not discriminate amphibious taxa from terrestrial taxa on the basis of body size or compactness profile data. To make our inference method accessible, spreadsheets (see supplementary material on the website), which allow anyone to infer a lissamphibian lifestyle solely from body size and bone compactness parameters, were produced. No such easy implementation of habitat inference models is found in earlier papers on this topic. [source]

Systematic lumped-parameter models for foundations based on polynomial-fraction approximation

Wen-Hwa Wu
Abstract Based on the approximation by polynomial-fraction, a series of systematic lumped-parameter models are developed in this paper for efficiently representing the dynamic behaviour of unbounded soil. Concise formulation is first employed to represent the dynamic flexibility function of foundation with a ratio of two polynomials. By defining an appropriate quadratic error function, the optimal coefficients of the polynomials can be directly solved from a system of linear equations. Through performing partial-fraction expansion on this polynomial-fraction and designing two basic discrete-element models corresponding to the partial fractions, systematic lumped-parameter models can be conveniently established by connecting these basic units in series. Since the systematic lumped-parameter models are configured without introducing any mass, the foundation input motion can be directly applied to these models for their applications to the analysis of seismic excitation. The effectiveness of these new models is strictly validated by successfully simulating a semi-infinite bar on an elastic foundation. Subsequently, these models are applied for representing the dynamic stiffness functions for different types of foundation. Comparison of the new models with the other existing lumped-parameter models is also made to illustrate their advantages in requiring fewer parameters and featuring a more systematic expansion. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Predicting ready biodegradability in the Japanese ministry of international trade and industry test

Jay Tunkel
Abstract Two new predictive models for assessing a chemical's biodegradability in the Japanese Ministry of International Trade and Industry (MITI) ready biodegradation test have been developed. The new methods use an approach similar to that in the existing BIOWIN© program, in which the probability of rapid biodegradation is estimated by means of multiple linear or nonlinear regression against counts of 36 chemical substructures (molecular fragments) plus molecular weight (mol wt). The data set used to develop the new models consisted of results (pass/no pass) from the MITI test for 884 discrete organic chemicals. This data set was first divided into randomly selected training and validation sets, and new coefficients were derived for the training set using the BIOWIN fragment library and mol wt as independent variables. Based on these results, the fragment library was then modified by deleting some fragments and adding or refining others, and the new set of independent variables (42 substructures and mol wt) was fit to the MITI data. The resulting linear and nonlinear regression models accurately classified 81% of the chemicals in an independent validation set. Like the established BIOWIN models, the MITI models are intended for use in chemical screening and in setting priorities for further review. [source]

Is management by objectives obsolete?

William F. Roth
Management by Objectives has been part of corporate dogma for many decades. But as its touted strengths rapidly become liabilities in the new global century, more empowering and flexible approaches sprout up as promising new models for performance management. The author examines the dampening effect Management by Objectives can have on creativity, teamwork, and the ability to respond to changes in the business. He also presents two cases of organizations that broke out of the mold: W.L. Gore and Associates' innovative approach to self-managing teams and Bridgeport Paper Company's even bolder experiment, in which employees developed and implemented a team-based organizational structure and team-directed processes for decision making, hiring and promotion, training, performance management (without MBO), rewards, and cross-team communication and integration. © 2009 Wiley Periodicals, Inc. [source]

Mouse models for human head and neck squamous cell carcinomas

Shi-Long Lu MD
Abstract Mouse models of human cancer play an important role in understanding the mechanisms of carcinogenesis and have accelerated the search for finding new molecular targets for cancer therapy. However, genetically engineered mouse models for head and neck squamous cell carcinoma (HNSCC) have only recently overcome major technical obstacles and begun to be explored. Here we review the current progress in the development of mouse models for human HNSCC, with emphasis on conditional transgenic and knockout mouse models. These new models faithfully recapitulate human HNSCC at both the pathologic and molecular levels. These animal models will not only be useful to define the roles of specific genes in HNSCC development and progression but will also provide a unique tool for developing and testing new therapeutic approaches. © 2006 Wiley Periodicals, Inc. Head Neck, 2006 [source]

The value of environmental modelling languages for building distributed hydrological models

Derek Karssenberg
Abstract An evaluation is made of the suitability of programming languages for hydrological modellers to create distributed, process-based hydrological models. Both system programming languages and high-level environmental modelling languages are evaluated based on a list of requirements for the optimal programming language for such models. This is illustrated with a case study, implemented using the PCRaster environmental modelling language to create a distributed, process-based hydrological model based on the concepts of KINEROS-EUROSEM. The main conclusion is that system programming languages are not ideal for hydrologists who are not computer programmers because the level of thinking of these languages is too strongly related to specialized computer science. A higher level environmental modelling language is better in the sense that it operates at the conceptual level of the hydrologist. This is because it contains operators that identify hydrological processes that operate on hydrological entities, such as two-dimensional maps, three-dimensional blocks and time-series. The case study illustrates the advantages of using an environmental modelling language as compared with system programming languages in fulfilling requirements on the level of thinking applied in the language, the reusability of the program code, the lack of technical details in the program, a short model development time and learnability. The study shows that environmental modelling languages are equally good as system programming languages in minimizing programming errors, but are worse in generic application and performance. It is expected that environmental modelling languages will be used in future mainly for development of new models that can be tailored to modelling aims and the field data available. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Improved accuracy for the Helmholtz equation in unbounded domains

Eli Turkel
Abstract Based on properties of the Helmholtz equation, we derive a new equation for an auxiliary variable. This reduces much of the oscillations of the solution leading to more accurate numerical approximations to the original unknown. Computations confirm the improved accuracy of the new models in both two and three dimensions. This also improves the accuracy when one wants the solution at neighbouring wavenumbers by using an expansion in k. We examine the accuracy for both waveguide and scattering problems as a function of k, h and the forcing mode l. The use of local absorbing boundary conditions is also examined as well as the location of the outer surface as functions of k. Connections with parabolic approximations are analysed. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Modelling of the fluid dynamic processes in a high-recirculation airlift reactor

David A. Sanders
Abstract This paper describes the creation of two models of the steady-state fluid dynamic processes occurring in a high-recirculation airlift reactor. The new models were created to provide information to assist in the design of a reactor, in particular considering the selection of parameters to adjust in order to achieve a steady state solution. The modelling of two-phase flow of air and water in small-scale airlift bioreactors is considered. This modelling was applied to the high-recirculation airlift reactor process. New computer simulations were created and tests performed to evaluate the new models. The results of this evaluation are presented. The evaluation showed that variation of the superficial gas velocity or the simultaneous variation of the downcomer and riser diameters could be used to produce a steady-state design solution. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Identifying measures for evaluating new models of nursing care: A survey of NSW nurse practitioners

Sandy Middleton RN BAppSc(Nursing) MN PhD
Health-care reforms in Australia and worldwide have seen the creation of the position of nurse practitioner (NP). To date, no protocol has been developed in Australia to guide the evaluation of this new role. All NSW authorized NPs were invited to participate in a self-administered questionnaire. Generic process and outcome measures of NP services were taken from a review of the literature. NPs were asked to determine how ,essential' each of these measures would be to describe their clinical practice. Of the 36 eligible authorized NPs in NSW, 30 returned completed questionnaires (83% response rate). The following measures were rated ,essential' by all (100%) NPs: presenting issue as stated by patient; current medications; patient satisfaction with education, quality of care received, and provider knowledge and skill. Our results provide a unique set of indicators with which to evaluate process and outcome measures of NP services. Standard outcome measures will enable NPs to evaluate their service efficiently and to benchmark against other NPs. [source]

The generalized assortment and best cutting stock length problems

John F. Raffensperger
Abstract This paper introduces two new one-dimensional cutting stock models: the generalized assortment problem (GAP) and the best cutting stock length (BSL) problem. These new models provide the potential to reduce waste to values lower than the optimum of current models, under the right management circumstances. In the GAP, management has a standard length and can select one or more of any additional custom stock lengths, and management wishes to minimize cutting stock waste. This model is different from existing models that assume that the selection is from a small fixed set of stock lengths. In the BSL problem, management chooses any number of custom stock lengths, but wishes to find the fewest custom stock lengths in order to have zero waste. Results show waste reductions of 80% with just one custom stock length compared with solutions from standard cutting stock formulations, when item lengths are long relative to the stock length. The models are most effective when the item lengths are nearly as long as the stock length. Solutions from the model have been implemented for a manufacturer. The model is easily generalized to allow multiple existing stock lengths and different costs. [source]

Learning for holistic care: addressing practical wisdom (phronesis) and the spiritual sphere

Helen L. Leathard
Abstract Title.,Learning for holistic care: addressing practical wisdom (phronesis) and the spiritual sphere. Aim., This paper is a discussion of practical wisdom (phronesis) and spirituality in holistic caring and strategies to facilitate their application in nurse education. Background.,Phronesis, with its inherent spiritual qualities, is an established aspect of the persona of excellent clinical leaders. There is a strong case for recognizing the value of this characteristic in all nurses, and a strategy is required for engendering the development of phronesis during nurse education. Data sources., Electronic searches of Google Scholar and CINAHL were conducted for English language publications in the period 1996,2008. Search terms included combinations of phronesis, spirituality, health, education, pharmacology, medicines and medication education, holistic care and spiritual care. Selection of items for inclusion was based on their pertinence to the arguments being developed and their value as leads to earlier material. Discussion., The links between the attributes of effective clinical leaders and those required for holistic caring are explicated and related to phronesis, the acquisition of which involves spiritual development. An explanatory account of phronesis and its applicability to nursing leads to an explanation of how its spiritual aspects in particular might be incorporated into learning for holistic care. Reference to research in medicines-related education illustrates how the principles can be applied in nurse education. Conclusion., Nursing quality could be enhanced if adequate opportunities for acquiring phronesis through experiential learning were provided in nursing curricula. Phronesis and spiritual care could be incorporated into existing models of nursing care or new models devised to use these critical concepts. [source]

A concept analysis of palliative care in the United States

Salimah H. Meghani RN MSN CRNP
Purpose., The purpose of this analysis is to trace the evolution of the concept of palliative in the United States, explicate its meanings, and draw comparisons with other related concepts such as hospice care and terminal care. Methods., Rodgers' evolutionary method was used as an organizing framework for the concept analysis. Data were collected from a review of CINAHL, MEDLINE, CANCERLIT, PsycINFO and Sociological Abstracts databases using ,palliative care' and ,United States' as keywords. Articles written in the English language, with an abstract, published between 1965 and 2003 were considered. Data were synthesized to identify attributes, antecedents and consequences of palliative care. Findings., There has been a significant evolution in understanding of the palliative care concept in the United States over the last few decades, which has resulted in the emergence of new models of palliative care. Four attributes of the current palliative care concept were identified: (1) total, active and individualized patient care, (2) support for the family, (3) interdisciplinary teamwork and (4) effective communication. Results reinforce that cure and palliation are not mutually exclusive categories. Conclusions., The scope of palliative care has evolved to include a wide range of patient populations who may not be appropriately termed ,dying' but for whom alleviation of suffering and improvement of quality of life may be very relevant goals. The ultimate success of the new models of palliative care will eventually rest upon the commitment of health professionals to recognize and integrate the changing concept of palliative care into everyday practice. [source]

Nursing needs of acutely ill older people

Karen Hancock BSc PhD
Background., Investigating older acutely ill hospitalized patients' nursing needs and quality of care is paramount, given the growing pressure on nurses to provide increasingly intensive levels of care to a growing older population while at the same time working with reduced staffing levels. Aims., The aims of this study were to determine: (1) important aspects of nursing care as perceived by older patients, their family member/carer who observed care during hospitalization, and nurses; (2) satisfaction levels of patients, family/carers and nurses on nursing care received; and (3) mismatches between nursing care priorities and satisfaction with nursing care. Methods., Two hundred and thirty-two acutely ill patients aged over 65 years, 99 carers/family members and 90 nurses completed the Caregiving Activities Survey, which measures importance of and satisfaction with various aspects of nursing care. Qualitative data, which qualified responses to survey items, were also obtained from participants. Results., Patients, carers and nurses perceived that carrying out doctors' orders was the most important aspect of nursing care, followed by physical care, psychosocial care and discharge planning. Nurses and carers rated physical care, psychosocial care and discharge planning more highly than patients. Physical care was rated highly by patients in terms of importance, but rated moderately in terms of satisfaction. Carers' and patients' ratings of satisfaction with physical care were lower than nurses' ratings of opportunities to provide it. The importance of discharge planning was rated highly by nurses but all groups were only moderately satisfied with this aspect of care. Study limitations., The findings do not apply to acutely ill older patients with confusion, mental illness or more than early stage dementia. Conclusions., Patients, nurses and family/carers were generally in agreement about the relative importance of particular aspects of nursing care. Nurses may need to communicate more effectively with older patients and their family carers about the particular roles they will play during the patient's hospital episode, the expectations they have of patients in the process of healing and recovery, and the reasons for the actions they take in aiding this process. The findings are useful in making nurses more aware of the expectations and needs of older hospital patients and their carers. They provide evidence for developing both new models of nursing care for this patient group, and nursing education programmes. [source]

Caring for Older Americans: The Future of Geriatric Medicine

American Geriatrics Society Core Writing Group of the Task Force on the Future of Geriatric Medicine
In response to the needs and demands of an aging population, geriatric medicine has grown rapidly during the past 3 decades. The discipline has defined its core values as well as the knowledge base and clinical skills needed to improve the health, functioning, and well-being of older persons and to provide appropriate palliative care. Geriatric medicine has developed new models of care, advanced the treatment of common geriatric conditions, and advocated for the health and health care of older persons. Nevertheless, at the beginning of the 21st century, the health care of older persons is at a crossroads. Despite the substantial progress that geriatric medicine has made, much more remains to be done to meet the healthcare needs of our aging population. The clinical, educational, and research approaches of the 20th century are unable to keep pace and require major revisions. Maintaining the status quo will mean falling further and further behind. The healthcare delivery and financing systems need fundamental redesign to improve quality and eliminate waste. The American Geriatrics Society (AGS) Task Force on the Future of Geriatric Medicine has identified five goals aimed at optimizing the health of older persons: ,,To ensure that every older person receives high-quality, patient-centered health care ,,To expand the geriatrics knowledge base ,,To increase the number of healthcare professionals who employ the principles of geriatric medicine in caring for older persons ,,To recruit physicians and other healthcare professionals into careers in geriatric medicine ,,To unite professional and lay groups in the effort to influence public policy to continually improve the health and health care of seniors Geriatric medicine cannot accomplish these goals alone. Accordingly, the Task Force has articulated a set of recommendations primarily aimed at the government, organizations, agencies, foundations, and other partners whose collaboration will be essential in accomplishing these goals. The vision described in this document and the accompanying recommendations are only the broad outline of an agenda for the future. Geriatric medicine, through its professional organizations and its partners, will need to mobilize resources to identify and implement the specific steps that will make the vision a reality. Doing so will require broad participation, consensus building, creativity, and perseverance. The consequences of inaction will be profound. The combination of a burgeoning number of older persons and an inadequately prepared, poorly organized physician workforce is a recipe for expensive, fragmented health care that does not meet the needs of our older population. By virtue of their unique skills and advocacy for the health of older persons, geriatricians can be key leaders of change to achieve the goals of geriatric medicine and optimize the health of our aging population. Nevertheless, the goals of geriatric medicine will be accomplished only if geriatricians and their partners work in a system that is designed to provide high-quality, efficient care and recognizes the value of geriatrics. [source]

Food limitation and insect outbreaks: complex dynamics in plant,herbivore models

Summary 1The population dynamics of many herbivorous insects are characterized by rapid outbreaks, during which the insects severely defoliate their host plants. These outbreaks are separated by periods of low insect density and little defoliation. In many cases, the underlying cause of these outbreaks is unknown. 2Mechanistic models are an important tool for understanding population outbreaks, but existing consumer,resource models predict that severe defoliation should happen much more often than is seen in nature. 3We develop new models to describe the population dynamics of plants and insect herbivores. Our models show that outbreaking insects may be resource-limited without inflicting unrealistic levels of defoliation. 4We tested our models against two different types of field data. The models successfully predict many major features of natural outbreaks. Our results demonstrate that insect outbreaks can be explained by a combination of food limitation in the herbivore and defoliation and intraspecific competition in the host plant. [source]

An operational model predicting autumn bird migration intensities for flight safety

Summary 1Forecasting migration intensity can improve flight safety and reduce the operational costs of collisions between aircraft and migrating birds. This is particularly true for military training flights, which can be rescheduled if necessary and often take place at low altitudes and during the night. Migration intensity depends strongly on weather conditions but reported effects of weather differ among studies. It is therefore unclear to what extent existing predictive models can be extrapolated to new situations. 2We used radar measurements of bird densities in the Netherlands to analyse the relationship between weather and nocturnal migration. Using our data, we tested the performance of three regression models that have been developed for other locations in Europe. We developed and validated new models for different combinations of years to test whether regression models can be used to predict migration intensity in independent years. Model performance was assessed by comparing model predictions against benchmark predictions based on measured migration intensity of the previous night and predictions based on a 6-year average trend. We also investigated the effect of the size of the calibration data set on model robustness. 3All models performed better than the benchmarks, but the mismatch between measurements and predictions was large for existing models. Model performance was best for newly developed regression models. The performance of all models was best at intermediate migration intensities. The performance of our models clearly increased with sample size, up to about 90 nocturnal migration measurements. Significant input variables included seasonal migration trend, wind profit, 24-h trend in barometric pressure and rain. 4Synthesis and applications. Migration intensities can be forecast with a regression model based on meteorological data. This and other existing models are only valid locally and cannot be extrapolated to new locations. Model development for new locations requires data sets with representative inter- and intraseasonal variability so that cross-validation can be applied effectively. The Royal Netherlands Air Force currently uses the regression model developed in this study to predict migration intensities 3 days ahead. This improves the reliability of migration intensity warnings and allows rescheduling of training flights if needed. [source]

Taking stock of naturalistic decision making

Raanan Lipshitz
Abstract We review the progress of naturalistic decision making (NDM) in the decade since the first conference on the subject in 1989. After setting out a brief history of NDM we identify its essential characteristics and consider five of its main contributions: recognition-primed decisions, coping with uncertainty, team decision making, decision errors, and methodology. NDM helped identify important areas of inquiry previously neglected (e.g. the use of expertise in sizing up situations and generating options), it introduced new models, conceptualizations, and methods, and recruited applied investigators into the field. Above all, NDM contributed a new perspective on how decisions (broadly defined as committing oneself to a certain course of action) are made. NDM still faces significant challenges, including improvement of the quantity and rigor of its empirical research, and confirming the validity of its prescriptive models. Copyright © 2001 John Wiley & Sons, Ltd. [source]

HRAS1 and LASS1 with APOE are associated with human longevity and healthy aging

AGING CELL, Issue 5 2010
S. Michal Jazwinski
Summary The search for longevity-determining genes in human has largely neglected the operation of genetic interactions. We have identified a novel combination of common variants of three genes that has a marked association with human lifespan and healthy aging. Subjects were recruited and stratified according to their genetically inferred ethnic affiliation to account for population structure. Haplotype analysis was performed in three candidate genes, and the haplotype combinations were tested for association with exceptional longevity. An HRAS1 haplotype enhanced the effect of an APOE haplotype on exceptional survival, and a LASS1 haplotype further augmented its magnitude. These results were replicated in a second population. A profile of healthy aging was developed using a deficit accumulation index, which showed that this combination of gene variants is associated with healthy aging. The variation in LASS1 is functional, causing enhanced expression of the gene, and it contributes to healthy aging and greater survival in the tenth decade of life. Thus, rare gene variants need not be invoked to explain complex traits such as aging; instead rare congruence of common gene variants readily fulfills this role. The interaction between the three genes described here suggests new models for cellular and molecular mechanisms underlying exceptional survival and healthy aging that involve lipotoxicity. [source]

Developing interdisciplinary maternity services policy in Canada.

Evaluation of a consensus workshop
Abstract Context, Four maternity/obstetrical care organizations, representing women, midwives, obstetricians and family doctors conducted interdisciplinary policy research under auspices of four key stakeholder groups. These projects teams and key stakeholders subsequently collaborated to develop consensus on strategies for improved maternity services in Ontario. Objectives, The objective of this study is to evaluate a 2-day research synthesis and consensus building conference to answer policy questions in relation to new models of interdisciplinary maternity care organizations in different settings in Ontario. Methods, The evaluation consisted of a scan of individual project activities and findings as were presented to an invited audience of key stakeholders at the consensus conference. This involved: participant observation with key informant consultation; a survey of attendees; pattern processing and sense making of project materials, consensus statements derived at the conference in the light of participant observation and survey material as pertaining to a complex system. The development of a systems framework for maternity care policy in Ontario was based on secondary analysis of the material. Findings, Conference participants were united on the importance of investment in maternity care for Ontario and the impending workforce crisis if adaptation of the workforce did not take place. The conference participants proposed reforming the current system that was seen as too rigid and inflexible in relation to the constraints of legislation, provider scope of practice and remuneration issues. However, not one model of interdisciplinary maternity/obstetrical care was endorsed. Consistency and coherence of models (rather than central standardization) through self-organization based on local needs was strongly endorsed. An understanding of primary maternity care models as subsystems of networked providers in complex health organizations and a wider social system emerged. The patterns identified were incorporated into a complexity framework to assist sense making to inform policy. Discussion, Coherence around core values, holism and synthesis with responsiveness to local needs and key stakeholders were themes that emerged consistent with complex adaptive systems principles. Respecting historical provider relationships and local history provided a background for change recognizing that systems evolve in part from where they have been. The building of functioning relationships was central through education and improved communication with ongoing feedback loops (positive and negative). Information systems and a flexible improved central and local organization of maternity services was endorsed. Education and improved communication through ongoing feedback loops (positive and negative) were central to building functioning relationships. Also, coordinated central organization with a flexible and adaptive local organization of maternity services was endorsed by participants. Conclusions, This evaluation used an approach comprising scoping, pattern processing and sense making. While the projects produced considerable typical research evidence, the key policy questions could not be addressed by this alone, and a process of synthesis and consensus building with stakeholder engagement was applied. An adaptive system with local needs driving a relationship based network of interdisciplinary groupings or teams with both bottom up and central leadership. A complexity framework enhanced sense making for the system approaches and understandings that emerged. [source]

Low-dimensional models for real time simulations of catalytic monoliths

AICHE JOURNAL, Issue 7 2009
Saurabh Y. Joshi
Abstract We present accurate low-dimensional models for real time simulation, control, and optimization of monolithic catalytic converters used in automobile exhaust treatment. These are derived directly by averaging the governing equations and using the concepts of internal and external mass transfer coefficients. They are expressed in terms of three concentration and two temperature modes and include washcoat diffusional effects without using the concept of the effectiveness factor. The models reduce to the classical two-phase models in the limit of vanishingly thin washcoat. The models are validated by simulating the transient behavior of a three-way converter for various cases and comparing the predictions with detailed solutions. It is shown that these new models are robust and accurate with practically acceptable error, speed up the computations by orders of magnitude, and can be used with confidence for the real time simulation and control of monolithic and other catalytic reactors. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]