WorldWideScience

Sample records for modeling population access

  1. Demographic population model for American shad: will access to additional habitat upstream of dams increase population sizes?

    Science.gov (United States)

    Harris, Julianne E.; Hightower, Joseph E.

    2012-01-01

    American shad Alosa sapidissima are in decline in their native range, and modeling possible management scenarios could help guide their restoration. We developed a density-dependent, deterministic, stage-based matrix model to predict the population-level results of transporting American shad to suitable spawning habitat upstream of dams on the Roanoke River, North Carolina and Virginia. We used data on sonic-tagged adult American shad and oxytetracycline-marked American shad fry both above and below dams on the Roanoke River with information from other systems to estimate a starting population size and vital rates. We modeled the adult female population over 30 years under plausible scenarios of adult transport, effective fecundity (egg production), and survival of adults (i.e., to return to spawn the next year) and juveniles (from spawned egg to age 1). We also evaluated the potential effects of increased survival for adults and juveniles. The adult female population size in the Roanoke River was estimated to be 5,224. With no transport, the model predicted a slow population increase over the next 30 years. Predicted population increases were highest when survival was improved during the first year of life. Transport was predicted to benefit the population only if high rates of effective fecundity and juvenile survival could be achieved. Currently, transported adults and young are less likely to successfully out-migrate than individuals below the dams, and the estimated adult population size is much smaller than either of two assumed values of carrying capacity for the lower river; therefore, transport is not predicted to help restore the stock under present conditions. Research on survival rates, density-dependent processes, and the impacts of structures to increase out-migration success would improve evaluation of the potential benefits of access to additional spawning habitat for American shad.

  2. The Long-Run Impact on Population and Income of Open Access to Land in a Model with Parental Altruism

    OpenAIRE

    Jon D. Harford

    2000-01-01

    Steady state levels of population and per capita income are examined using a Becker-Barro (1988) style of model of an economy with identical altruistic parents bearing costly children who receive bequests of capital and land. Inspired by the work of North (1981) and others, the problem of open access land with ancillary negative effects on private (but not public) productivity of capital is examined. It is seen that open access to land can lead to overpopulation in a ceteris paribus sense, an...

  3. Modelling Risk to US Military Populations from Stopping Blanket Mandatory Polio Vaccination (Open Access Publisher’s Version)

    Science.gov (United States)

    2017-09-14

    2014. [24] “United Nations, Department of Economic and Social Affairs, Population Division, World Population Prospects, the 2015 Revision,” http...Research Article Modelling Risk to US Military Populations from Stopping Blanket Mandatory Polio Vaccination Colleen Burgess,1,2 Andrew Burgess,2 and...for polio transmission within military populations interacting with locals in a polio-endemic region to evaluate changes in vaccination policy

  4. [Access to care for vulnerable populations].

    Science.gov (United States)

    Geeraert, Jérémy; Rivollier, Elisabeth

    2014-11-01

    Accessing hospital care is a privilege for a growing proportion of the population in situations of economic and social precarity. It is therefore important that caregivers understand these difficulties in order to adapt their nursing approach.

  5. Textual information access statistical models

    CERN Document Server

    Gaussier, Eric

    2013-01-01

    This book presents statistical models that have recently been developed within several research communities to access information contained in text collections. The problems considered are linked to applications aiming at facilitating information access:- information extraction and retrieval;- text classification and clustering;- opinion mining;- comprehension aids (automatic summarization, machine translation, visualization).In order to give the reader as complete a description as possible, the focus is placed on the probability models used in the applications

  6. Population distribution, settlement patterns and accessibility across Africa in 2010.

    Directory of Open Access Journals (Sweden)

    Catherine Linard

    Full Text Available The spatial distribution of populations and settlements across a country and their interconnectivity and accessibility from urban areas are important for delivering healthcare, distributing resources and economic development. However, existing spatially explicit population data across Africa are generally based on outdated, low resolution input demographic data, and provide insufficient detail to quantify rural settlement patterns and, thus, accurately measure population concentration and accessibility. Here we outline approaches to developing a new high resolution population distribution dataset for Africa and analyse rural accessibility to population centers. Contemporary population count data were combined with detailed satellite-derived settlement extents to map population distributions across Africa at a finer spatial resolution than ever before. Substantial heterogeneity in settlement patterns, population concentration and spatial accessibility to major population centres is exhibited across the continent. In Africa, 90% of the population is concentrated in less than 21% of the land surface and the average per-person travel time to settlements of more than 50,000 inhabitants is around 3.5 hours, with Central and East Africa displaying the longest average travel times. The analyses highlight large inequities in access, the isolation of many rural populations and the challenges that exist between countries and regions in providing access to services. The datasets presented are freely available as part of the AfriPop project, providing an evidence base for guiding strategic decisions.

  7. Wireless-accessible sensor populations for monitoring biological variables

    NARCIS (Netherlands)

    Mazzu, Marco; Scalvini, Simonetta; Giordano, A.; Frumento, E.; Wells, Hannah; Lokhorst, C.; Glisenti, Fulvio

    2008-01-01

    The current health-care infrastructure is generally considered to be inadequate to meet the needs of an increasingly older population. We have investigated the feasibility of a passive in-home monitoring system based on wireless accessible sensor populations (WASP). In an EU-funded project we have

  8. Accessing patient-centered care using the advanced access model.

    Science.gov (United States)

    Tantau, Catherine

    2009-01-01

    Waits and delays for healthcare are legendary. These delays are not only frustrating and potentially hazardous for patients and providers but also represent significant cost to office practices. The traditional medical model that defines urgent care versus routine care is a vain and futile attempt to sort demand. This approach is at constant odds with patients' definition of urgency. Trusting patients to determine when and how they want to access care makes sense from a customer service perspective. If approached systematically using the principles of Advanced Access, patient demand patterns can be tracked to forecast demand. These demand patterns become the template for deploying the resources necessary to meet patients' needs. Although not a simple journey, the transformation to Advanced Access provides an entree to patient-centered care where patients can say, "I get exactly the care I want and need, when I want and need it."

  9. Accessibility to Nodes of Interest: Demographic Weighting the Logistic Model

    Directory of Open Access Journals (Sweden)

    Gioacchino DE CANDIA

    2015-11-01

    Full Text Available This research fits into the genre of spatial analysis, aimed at better understanding of population dynamics in relation to the presence and distribution of infrastructure and related services. Specifically, the analysis uses a model of the gravitational type, based on the assumption of the impedance (attractiveness territorial, based on a curve of type logistics to determine the accessibility of the same, to which to add a system of weights. In this sense, the model was weighted according to the population, to determine the level of “population served” in terms of infrastructure and related services included in the model.

  10. Modeling Exponential Population Growth

    Science.gov (United States)

    McCormick, Bonnie

    2009-01-01

    The concept of population growth patterns is a key component of understanding evolution by natural selection and population dynamics in ecosystems. The National Science Education Standards (NSES) include standards related to population growth in sections on biological evolution, interdependence of organisms, and science in personal and social…

  11. Modeling Population Growth and Extinction

    Science.gov (United States)

    Gordon, Sheldon P.

    2009-01-01

    The exponential growth model and the logistic model typically introduced in the mathematics curriculum presume that a population grows exclusively. In reality, species can also die out and more sophisticated models that take the possibility of extinction into account are needed. In this article, two extensions of the logistic model are considered,…

  12. [Determining Factors in the Access to Mental Health Services by the Adult Colombian Population].

    Science.gov (United States)

    González, Lina María; Peñaloza, Rolando Enrique; Matallana, María Alexandra; Gil, Fabián; Gómez-Restrepo, Carlos; Landaeta, Angela Patricia Vega

    2016-12-01

    Access to mental health services by people with mental disorders has traditionally been limited, and is associated with attitudinal, social, and structural variables. To analyse the factors that determine access to mental health services by the adult population (18-44 years old) in Colombia, from the results obtained in the 2015 National Mental Health Survey. Analysis of variables of access to attention in mental health care for adults. The reasons for not consulting were classified as barriers of behavioural supply and demand. To analyse the factors associated with access to mental health services in the Colombian adult population, the use of health services in the last 12 months for emotional, nervous or mental health problems was taken into account, as well as associated variables such as demographic characteristics, occupational activity, affiliation to social security, and health status variables. The relationships between these variables were estimated using bivariate multinomial logistic regression models. Rural residence, being married, and having a chronic disease were associated with the decision to consult or not to consult the doctor. Further studies should be conducted to evaluate the situation as regards mental health care access, as well as to determine the potential factors associated with these limitations. Copyright © 2016 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

  13. Modeled population exposures to ozone

    Data.gov (United States)

    U.S. Environmental Protection Agency — Population exposures to ozone from APEX modeling for combinations of potential future air quality and demographic change scenarios. This dataset is not publicly...

  14. Redwoods: a population model.

    Science.gov (United States)

    Bosch, C A

    1971-04-23

    The chief conclusion to be drawn from the results of this study is that redwoods are amazingly vigorous. The results support both the lumber companies and the conservationists. There is no question that old growth giant redwoods must be preserved. Only commercial greed could be a basis for refuting that stand. On the other hand, the lumber companies seem to be supported in their contention that redwoods can be farmed without driving them to extinction. The central issue revolves around the old trees. And here profit is the big factor. Lumbering is an important industry in California, and redwood lumbering represents about 20 percent of the industry (l). Most of the big names in timber, such as Weyerhaeuser and Georgia-Pacific, are involved in logging the California redwood. At the current rate of logging, particularly of old growth stands, the Bank of America estimates that employment in Humboldt County will be down significantly by 1975 (4). It has been argued that tourism would more than compensate for the lower employment in logging. But not if the trees that the tourists come to see are gone. Why can't young and mature trees be harvested at a reasonable rate, the old trees saved, and both tourism and logging flourish? The question posed earlier has been answered. Redwood growth and survival can be modeled, using matrix methods in a new context. Meaningful conclusions may be drawn. And the results are sufficiently tantalizing to inspire further research.

  15. Stellar Atmospheric Modelling for the ACCESS Program

    Science.gov (United States)

    Morris, Matthew; Kaiser, Mary Elizabeth; Bohlin, Ralph; Kurucz, Robert; ACCESS Team

    2018-01-01

    A goal of the ACCESS program (Absolute Color Calibration Experiment for Standard Stars) is to enable greater discrimination between theoretical astrophysical models and observations, where the comparison is limited by systematic errors associated with the relative flux calibration of the targets. To achieve these goals, ACCESS has been designed as a sub-orbital rocket borne payload and ground calibration program, to establish absolute flux calibration of stellar targets at flight candidates, as well as a selection of A and G stars from the CALSPEC database. Stellar atmosphere models were generated using Atlas 9 and Atlas 12 Kurucz stellar atmosphere software. The effective temperature, log(g), metallicity, and redenning were varied and the chi-squared statistic was minimized to obtain a best-fit model. A comparison of these models and the results from interpolation between grids of existing models will be presented. The impact of the flexibility of the Atlas 12 input parameters (e.g. solar metallicity fraction, abundances, microturbulent velocity) is being explored.

  16. A service-oriented data access control model

    Science.gov (United States)

    Meng, Wei; Li, Fengmin; Pan, Juchen; Song, Song; Bian, Jiali

    2017-01-01

    The development of mobile computing, cloud computing and distributed computing meets the growing individual service needs. Facing with complex application system, it's an urgent problem to ensure real-time, dynamic, and fine-grained data access control. By analyzing common data access control models, on the basis of mandatory access control model, the paper proposes a service-oriented access control model. By regarding system services as subject and data of databases as object, the model defines access levels and access identification of subject and object, and ensures system services securely to access databases.

  17. Perti Net-Based Workflow Access Control Model

    Institute of Scientific and Technical Information of China (English)

    陈卓; 骆婷; 石磊; 洪帆

    2004-01-01

    Access control is an important protection mechanism for information systems. This paper shows how to make access control in workflow system. We give a workflow access control model (WACM) based on several current access control models. The model supports roles assignment and dynamic authorization. The paper defines the workflow using Petri net. It firstly gives the definition and description of the workflow, and then analyzes the architecture of the workflow access control model (WACM). Finally, an example of an e-commerce workflow access control model is discussed in detail.

  18. Foundation for a Time Interval Access Control Model

    National Research Council Canada - National Science Library

    Afinidad, Francis B; Levin, Timothy E; Irvine, Cynthia E; Nguyen, Thuy D

    2005-01-01

    A new model for representing temporal access control policies is introduced. In this model, temporal authorizations are represented by time attributes associated with both subjects and objects, and a time interval access graph...

  19. Fluctuations in a coupled population model

    International Nuclear Information System (INIS)

    Jakeman, E; Hopcraft, K I; Matthews, J O

    2005-01-01

    We investigate a discrete Markov process in which the immigration of individuals into one population is controlled by the fluctuations in another. We examine the effect of coupling back the second population to the first through a similar mechanism and derive exact solutions for the generating functions of the population statistics. We show that a stationary state exists over a certain parameter range and obtain expressions for moments and correlation functions in this regime. When more than two populations are coupled, cyclically transient oscillations and periodic behaviour of correlation functions are predicted. We demonstrate that if the initial distribution of either population is stable, or more generally has a power-law tail that falls off like N -(1+α) (0 < α < 1), then for certain parameter values there exists a stationary state that is also power law but not stable. This stationary state cannot be accessed from a single multiple immigrant population model, but arises solely from the nonlinear interaction of the coupled system

  20. Attributes Enhanced Role-Based Access Control Model

    DEFF Research Database (Denmark)

    Mahmood Rajpoot, Qasim; Jensen, Christian D.; Krishnan, Ram

    2015-01-01

    as an important area of research. In this paper, we propose an access control model that combines the two models in a novel way in order to unify their benefits. Our approach provides a fine-grained access control mechanism that not only takes contextual information into account while making the access control...... decisions but is also suitable for applications where access to resources is controlled by exploiting contents of the resources in the policy....

  1. Modeling Political Populations with Bacteria

    Science.gov (United States)

    Cleveland, Chris; Liao, David

    2011-03-01

    Results from lattice-based simulations of micro-environments with heterogeneous nutrient resources reveal that competition between wild-type and GASP rpoS819 strains of E. Coli offers mutual benefit, particularly in nutrient deprived regions. Our computational model spatially maps bacteria populations and energy sources onto a set of 3D lattices that collectively resemble the topology of North America. By implementing Wright-Fishcer re- production into a probabilistic leap-frog scheme, we observe populations of wild-type and GASP rpoS819 cells compete for resources and, yet, aid each other's long term survival. The connection to how spatial political ideologies map in a similar way is discussed.

  2. ARCAS (ACACIA Regional Climate-data Access System) -- a Web Access System for Climate Model Data Access, Visualization and Comparison

    Science.gov (United States)

    Hakkarinen, C.; Brown, D.; Callahan, J.; hankin, S.; de Koningh, M.; Middleton-Link, D.; Wigley, T.

    2001-05-01

    A Web-based access system to climate model output data sets for intercomparison and analysis has been produced, using the NOAA-PMEL developed Live Access Server software as host server and Ferret as the data serving and visualization engine. Called ARCAS ("ACACIA Regional Climate-data Access System"), and publicly accessible at http://dataserver.ucar.edu/arcas, the site currently serves climate model outputs from runs of the NCAR Climate System Model for the 21st century, for Business as Usual and Stabilization of Greenhouse Gas Emission scenarios. Users can select, download, and graphically display single variables or comparisons of two variables from either or both of the CSM model runs, averaged for monthly, seasonal, or annual time resolutions. The time length of the averaging period, and the geographical domain for download and display, are fully selectable by the user. A variety of arithmetic operations on the data variables can be computed "on-the-fly", as defined by the user. Expansions of the user-selectable options for defining analysis options, and for accessing other DOD-compatible ("Distributed Ocean Data System-compatible") data sets, residing at locations other than the NCAR hardware server on which ARCAS operates, are planned for this year. These expansions are designed to allow users quick and easy-to-operate web-based access to the largest possible selection of climate model output data sets available throughout the world.

  3. Access to general health care services by a New Zealand population with serious mental illness.

    Directory of Open Access Journals (Sweden)

    Wheeler A

    2014-03-01

    Full Text Available INTRODUCTION: Literature suggests that good quality health care access can have a positive impact on the health of people with serious mental illness (SMI, but literature relating to patterns of access by this group is equivocal. AIM: This study was designed to explore health care access patterns in a group of people with SMI and to compare them with a general New Zealand population group, in order for health providers to understand how they might contribute to positive health outcomes for this group. METHODS: The study surveyed 404 mental health consumers aged 18-65 years receiving care from one district health board in Auckland about their patterns of health care access. Results were compared with those from the New Zealand Health Survey of the general population. RESULTS: Findings suggest that the SMI consumer respondents had poorer physical health than the general population respondents, accessed health care services in more complex ways and were more particular about who they accessed for their care than the general population respondents. There was some concern from SMI consumers around discrimination from health care providers. The study also suggested that some proactive management with SMI consumers for conditions such as metabolic syndrome was occurring within the health care community. DISCUSSION: The first point of access for SMI consumers with general health problems is not always the family general practitioner and so other health professionals may sometimes need to consider the mental and physical health of such consumers in a wider context than their own specialism.

  4. Population growth, accessibility spillovers and persistent borders: Historical growth in West-European municipalities.

    Science.gov (United States)

    Jacobs-Crisioni, Chris; Koomen, Eric

    2017-06-01

    Lack of cross-border transport supply has repeatedly been blamed for the fact that national borders limit spatial interaction and, consequently, the growth of border regions. This study applies an accessibility approach to investigate for most municipalities in ten countries in mainland West Europe if foreign transport supply is lagging behind, and if population growth in these municipalities has been affected by the limits that national borders have imposed on market access. To do so, data describing historical population changes and road networks between 1961 and 2011 have been used. The results show that in the study area, cross-border transport accessibility was not at a disadvantage in 1961 and has since then grown even more than domestic accessibility. However, municipal population growth has depended almost exclusively on domestic market access. Processes of economic international integration in the study area are found to coincide with the growth of cross-border accessibility, but do not have a clear coincidence with the effects of cross-border accessibility on population growth.

  5. Matrix population models from 20 studies of perennial plant populations

    Science.gov (United States)

    Ellis, Martha M.; Williams, Jennifer L.; Lesica, Peter; Bell, Timothy J.; Bierzychudek, Paulette; Bowles, Marlin; Crone, Elizabeth E.; Doak, Daniel F.; Ehrlen, Johan; Ellis-Adam, Albertine; McEachern, Kathryn; Ganesan, Rengaian; Latham, Penelope; Luijten, Sheila; Kaye, Thomas N.; Knight, Tiffany M.; Menges, Eric S.; Morris, William F.; den Nijs, Hans; Oostermeijer, Gerard; Quintana-Ascencio, Pedro F.; Shelly, J. Stephen; Stanley, Amanda; Thorpe, Andrea; Tamara, Ticktin; Valverde, Teresa; Weekley, Carl W.

    2012-01-01

    Demographic transition matrices are one of the most commonly applied population models for both basic and applied ecological research. The relatively simple framework of these models and simple, easily interpretable summary statistics they produce have prompted the wide use of these models across an exceptionally broad range of taxa. Here, we provide annual transition matrices and observed stage structures/population sizes for 20 perennial plant species which have been the focal species for long-term demographic monitoring. These data were assembled as part of the 'Testing Matrix Models' working group through the National Center for Ecological Analysis and Synthesis (NCEAS). In sum, these data represent 82 populations with >460 total population-years of data. It is our hope that making these data available will help promote and improve our ability to monitor and understand plant population dynamics.

  6. MOFAC : model for fine grained access control

    OpenAIRE

    2014-01-01

    M.Sc. (Computer Science) Computer security is a key component in any computer system. Traditionally computers were not connected to one another. This centralized configuration made the implementation of computer security a relatively easy task. The closed nature of the system limited the number of unknown factors that could cause security breaches. The users and their access rights were generally well defined and the system was protected from outside threats through simple, yet effective c...

  7. Household computer and Internet access: The digital divide in a pediatric clinic population

    Science.gov (United States)

    Carroll, Aaron E.; Rivara, Frederick P.; Ebel, Beth; Zimmerman, Frederick J.; Christakis, Dimitri A.

    2005-01-01

    Past studies have noted a digital divide, or inequality in computer and Internet access related to socioeconomic class. This study sought to measure how many households in a pediatric primary care outpatient clinic had household access to computers and the Internet, and whether this access differed by socio-economic status or other demographic information. We conducted a phone survey of a population-based sample of parents with children ages 0 to 11 years old. Analyses assessed predictors of having home access to a computer, the Internet, and high-speed Internet service. Overall, 88.9% of all households owned a personal computer, and 81.4% of all households had Internet access. Among households with Internet access, 48.3% had high speed Internet at home. There were statistically significant associations between parental income or education and home computer ownership and Internet access. However, the impact of this difference was lessened by the fact that over 60% of families with annual household income of $10,000–$25,000, and nearly 70% of families with only a high-school education had Internet access at home. While income and education remain significant predictors of household computer and internet access, many patients and families at all economic levels have access, and might benefit from health promotion interventions using these modalities. PMID:16779012

  8. Incorporating territory compression into population models

    NARCIS (Netherlands)

    Ridley, J; Komdeur, J; Sutherland, WJ; Sutherland, William J.

    The ideal despotic distribution, whereby the lifetime reproductive success a territory's owner achieves is unaffected by population density, is a mainstay of behaviour-based population models. We show that the population dynamics of an island population of Seychelles warblers (Acrocephalus

  9. Task Delegation Based Access Control Models for Workflow Systems

    Science.gov (United States)

    Gaaloul, Khaled; Charoy, François

    e-Government organisations are facilitated and conducted using workflow management systems. Role-based access control (RBAC) is recognised as an efficient access control model for large organisations. The application of RBAC in workflow systems cannot, however, grant permissions to users dynamically while business processes are being executed. We currently observe a move away from predefined strict workflow modelling towards approaches supporting flexibility on the organisational level. One specific approach is that of task delegation. Task delegation is a mechanism that supports organisational flexibility, and ensures delegation of authority in access control systems. In this paper, we propose a Task-oriented Access Control (TAC) model based on RBAC to address these requirements. We aim to reason about task from organisational perspectives and resources perspectives to analyse and specify authorisation constraints. Moreover, we present a fine grained access control protocol to support delegation based on the TAC model.

  10. Metrics and Evaluation Models for Accessible Television

    DEFF Research Database (Denmark)

    Li, Dongxiao; Looms, Peter Olaf

    2014-01-01

    The adoption of the UN Convention on the Rights of Persons with Disabilities (UN CRPD) in 2006 has provided a global framework for work on accessibility, including information and communication technologies and audiovisual content. One of the challenges facing the application of the UN CRPD...... number of platforms on which audiovisual content needs to be distributed, requiring very clear multiplatform architectures to facilitate interworking and assure interoperability. As a consequence, the regular evaluations of progress being made by signatories to the UN CRPD protocol are difficult...

  11. A global workspace model for phenomenal and access consciousness.

    Science.gov (United States)

    Raffone, Antonino; Pantani, Martina

    2010-06-01

    Both the global workspace theory and Block's distinction between phenomenal and access consciousness, are central in the current debates about consciousness and the neural correlates of consciousness. In this article, a unifying global workspace model for phenomenal and access consciousness is proposed. In the model, recurrent neural interactions take place in distinct yet interacting access and phenomenal brain loops. The effectiveness of feedback signaling onto sensory cortical maps is emphasized for the neural correlates of phenomenal consciousness. Two forms of top-down attention, attention for perception and attention for access, play differential roles for phenomenal and access consciousness. The model is implemented in a neural network form, with the simulation of single and multiple visual object processing, and of the attentional blink. 2010 Elsevier Inc. All rights reserved.

  12. Improving access to health care for chronic hepatitis B among migrant Chinese populations: A systematic mixed methods review of barriers and enablers

    OpenAIRE

    Vedio, A.; Liu, E. Z. H.; Lee, A. C. K.; Salway, S.

    2017-01-01

    Summary Migrant Chinese populations in Western countries have a high prevalence of chronic hepatitis B but often experience poor access to health care and late diagnosis. This systematic review aimed to identify obstacles and supports to timely and appropriate health service use among these populations. Systematic searches resulted in 48 relevant studies published between 1996 and 2015. Data extraction and synthesis were informed by models of healthcare access that highlight the interplay of ...

  13. Asymptotic performance modelling of DCF protocol with prioritized channel access

    Science.gov (United States)

    Choi, Woo-Yong

    2017-11-01

    Recently, the modification of the DCF (Distributed Coordination Function) protocol by the prioritized channel access was proposed to resolve the problem that the DCF performance worsens exponentially as more nodes exist in IEEE 802.11 wireless LANs. In this paper, an asymptotic analytical performance model is presented to analyze the MAC performance of the DCF protocol with the prioritized channel access.

  14. Stochastic population dynamic models as probability networks

    Science.gov (United States)

    M.E. and D.C. Lee. Borsuk

    2009-01-01

    The dynamics of a population and its response to environmental change depend on the balance of birth, death and age-at-maturity, and there have been many attempts to mathematically model populations based on these characteristics. Historically, most of these models were deterministic, meaning that the results were strictly determined by the equations of the model and...

  15. Permanent Genetic Access to Transiently Active Neurons via TRAP: Targeted Recombination in Active Populations

    OpenAIRE

    Guenthner, Casey J.; Miyamichi, Kazunari; Yang, Helen H.; Heller, H. Craig; Luo, Liqun

    2013-01-01

    Targeting genetically encoded tools for neural circuit dissection to relevant cellular populations is a major challenge in neurobiology. We developed a new approach, Targeted Recombination in Active Populations (TRAP), to obtain genetic access to neurons that were activated by defined stimuli. This method utilizes mice in which the tamoxifen-dependent recombinase CreERT2 is expressed in an activity-dependent manner from the loci of the immediate early genes Arc and Fos. Active cells that expr...

  16. Genetic diversity and population structure of Pisum sativum accessions for marker-trait association of lipid content

    Directory of Open Access Journals (Sweden)

    Sajjad Ahmad

    2015-06-01

    Full Text Available Field pea (Pisum sativum L. is an important protein-rich pulse crop produced globally. Increasing the lipid content of Pisum seeds through conventional and contemporary molecular breeding tools may bring added value to the crop. However, knowledge about genetic diversity and lipid content in field pea is limited. An understanding of genetic diversity and population structure in diverse germplasm is important and a prerequisite for genetic dissection of complex characteristics and marker-trait associations. Fifty polymorphic microsatellite markers detecting a total of 207 alleles were used to obtain information on genetic diversity, population structure and marker-trait associations. Cluster analysis was performed using UPGMA to construct a dendrogram from a pairwise similarity matrix. Pea genotypes were divided into five major clusters. A model-based population structure analysis divided the pea accessions into four groups. Percentage lipid content in 35 diverse pea accessions was used to find potential associations with the SSR markers. Markers AD73, D21, and AA5 were significantly associated with lipid content using a mixed linear model (MLM taking population structure (Q and relative kinship (K into account. The results of this preliminary study suggested that the population could be used for marker-trait association mapping studies.

  17. Accessibility Modeling for a Developing Economy: The Case of Inter ...

    African Journals Online (AJOL)

    Be it that, given the prevailing income levels and fast growing population coupled with ever rising rate of travel costs, accessibility has and will continue to be considerably reduced particularly for employment and other essential activities located principally in industrial and urban centers of the Lake Basin. Services including ...

  18. Transforming community access to space science models

    Science.gov (United States)

    MacNeice, Peter; Hesse, Michael; Kuznetsova, Maria; Maddox, Marlo; Rastaetter, Lutz; Berrios, David; Pulkkinen, Antti

    2012-04-01

    Researching and forecasting the ever changing space environment (often referred to as space weather) and its influence on humans and their activities are model-intensive disciplines. This is true because the physical processes involved are complex, but, in contrast to terrestrial weather, the supporting observations are typically sparse. Models play a vital role in establishing a physically meaningful context for interpreting limited observations, testing theory, and producing both nowcasts and forecasts. For example, with accurate forecasting of hazardous space weather conditions, spacecraft operators can place sensitive systems in safe modes, and power utilities can protect critical network components from damage caused by large currents induced in transmission lines by geomagnetic storms.

  19. Health Benefits for Vocational Rehabilitation Consumers: Comparison of Access Rates with Workers in the General Population

    Science.gov (United States)

    Lustig, Daniel C.; Strauser, David R.

    2010-01-01

    Access to health insurance is one of the critical aspects of securing employment for people with disabilities. This study investigated whether vocational rehabilitation consumers secured employment with an employer who offered health insurance at similar rates to workers in the general population. In general, the results show that vocational…

  20. Mathematical Modeling of Extinction of Inhomogeneous Populations

    Science.gov (United States)

    Karev, G.P.; Kareva, I.

    2016-01-01

    Mathematical models of population extinction have a variety of applications in such areas as ecology, paleontology and conservation biology. Here we propose and investigate two types of sub-exponential models of population extinction. Unlike the more traditional exponential models, the life duration of sub-exponential models is finite. In the first model, the population is assumed to be composed clones that are independent from each other. In the second model, we assume that the size of the population as a whole decreases according to the sub-exponential equation. We then investigate the “unobserved heterogeneity”, i.e. the underlying inhomogeneous population model, and calculate the distribution of frequencies of clones for both models. We show that the dynamics of frequencies in the first model is governed by the principle of minimum of Tsallis information loss. In the second model, the notion of “internal population time” is proposed; with respect to the internal time, the dynamics of frequencies is governed by the principle of minimum of Shannon information loss. The results of this analysis show that the principle of minimum of information loss is the underlying law for the evolution of a broad class of models of population extinction. Finally, we propose a possible application of this modeling framework to mechanisms underlying time perception. PMID:27090117

  1. A Population-based Study of Age Inequalities in Access to Palliative Care Among Cancer Patients

    Science.gov (United States)

    Burge, Frederick I.; Lawson, Beverley J.; Johnston, Grace M.; Grunfeld, Eva

    2013-01-01

    Background Inequalities in access to palliative care programs (PCP) by age have been shown to exist in Canada and elsewhere. Few studies have been able to provide greater insight by simultaneously adjusting for multiple demographic, health service, and socio-cultural indicators. Objective To re-examine the relationship between age and registration to specialized community-based PCP programs among cancer patients and identify the multiple indicators contributing to these inequalities. Methods This retrospective, population-based study was a secondary data analysis of linked individual level information extracted from 6 administrative health databases and contextual (neighborhood level) data from provincial and census information. Subjects included all adults who died due to cancer between 1998 and 2003 living within 2 District Health Authorities in the province of Nova Scotia, Canada. The relationship between registration in a PCP and age was examined using hierarchical nonlinear regression modeling techniques. Identification of potential patient and ecologic contributing indicators was guided by Andersen’s conceptual model of health service utilization. Results Overall, 66% of 7511 subjects were registered with a PCP. Older subjects were significantly less likely than those center had a major impact on registration. Conclusions Age continues to be a significant predictor of PCP registration in Nova Scotia even after controlling for the confounding effects of many new demographic, health service, and ecologic indicators. PMID:19300309

  2. SSR and morphological trait based population structure analysis of 130 diverse flax (Linum usitatissimum L.) accessions.

    Science.gov (United States)

    Choudhary, Shashi Bhushan; Sharma, Hariom Kumar; Kumar, Arroju Anil; Maruthi, Rangappa Thimmaiah; Mitra, Jiban; Chowdhury, Isholeena; Singh, Binay Kumar; Karmakar, Pran Gobinda

    2017-02-01

    A total of 130 flax accessions of diverse morphotypes and worldwide origin were assessed for genetic diversity and population structure using 11 morphological traits and microsatellite markers (15 gSSRs and 7 EST-SSRs). Analysis performed after classifying these accessions on the basis of plant height, branching pattern, seed size, Indian/foreign origin into six categories called sub-populations viz. fibre type exotic, fibre type indigenous, intermediate type exotic, intermediate type indigenous, linseed type exotic and linseed type indigenous. The study assessed different diversity indices, AMOVA, population structure and included a principal coordinate analysis based on different marker systems. The highest diversity was exhibited by gSSR markers (SI=0.46; He=0.31; P=85.11). AMOVA based on all markers explained significant difference among fibre type, intermediate type and linseed type populations of flax. In terms of variation explained by different markers, EST-SSR markers (12%) better differentiated flax populations compared to morphological (9%) and gSSR (6%) markers at P=0.01. The maximum Nei's unbiased genetic distance (D=0.11) was observed between fibre type and linseed type exotic sub-populations based on EST-SSR markers. The combined structure analysis by using all markers grouped Indian fibre type accessions (63.4%) in a separate cluster along with the Indian intermediate type (48.7%), whereas Indian accessions (82.16%) of linseed type constituted an independent cluster. These findings were supported by the results of the principal coordinate analysis. Morphological markers employed in the study found complementary with microsatellite based markers in deciphering genetic diversity and population structure of the flax germplasm. Copyright © 2016 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.

  3. The challenges and recommendations of accessing to affected population for humanitarian assistance: a narrative review.

    Science.gov (United States)

    Moslehi, Shandiz; Fatemi, Farin; Mahboubi, Mohammad; Mozafarsaadati, Hossein; Karami, Shirzad

    2014-11-17

    Access to affected people pays an important role in United Nation Organization for Coordination and Humanitarian Affairs (OCHA). The aim of this article is to identify the main obstacles of humanitarian access and the humanitarian organization responses to these obstacles and finally suggest some recommendations and strategies. In this narrative study the researchers searched in different databases. This study focused on the data from five countries in the following areas: access challenges and constraints to affected population and response strategies selected for operations in the affected countries by humanitarian organizations. Three main issues were studied: security threats, bureaucratic restrictions and indirect constraint, which each of them divided to three subcategories. Finally, nine related subcategories emerged from this analysis. Most of these constraints relate to political issues. Changes in policy structures, negotiations and advocacy can be recommended to solve most of the problems in access issues.

  4. Bring Your Own Device - Providing Reliable Model of Data Access

    Directory of Open Access Journals (Sweden)

    Stąpór Paweł

    2016-10-01

    Full Text Available The article presents a model of Bring Your Own Device (BYOD as a model network, which provides the user reliable access to network resources. BYOD is a model dynamically developing, which can be applied in many areas. Research network has been launched in order to carry out the test, in which as a service of BYOD model Work Folders service was used. This service allows the user to synchronize files between the device and the server. An access to the network is completed through the wireless communication by the 802.11n standard. Obtained results are shown and analyzed in this article.

  5. Increasing Contraceptive Access for Hard-to-Reach Populations With Vouchers and Social Franchising in Uganda.

    Science.gov (United States)

    Bellows, Benjamin; Mackay, Anna; Dingle, Antonia; Tuyiragize, Richard; Nnyombi, William; Dasgupta, Aisha

    2017-09-27

    From 2001 to 2011, modern contraceptive prevalence in Uganda increased from 18% to 26%. However, modern method use, in particular use of long-acting reversible contraceptives (LARCs) and permanent methods (PMs), remained low. In the 2011 Uganda Demographic and Health Survey, only 1 of 5 married women used a LARC or PM even though 34% indicated an unmet need for contraception. Between 2011 and 2014, a social franchise and family planning voucher program, supporting 400 private facilities to provide family planning counseling and broaden contraceptive choice by adding LARCs and PMs to the service mix, offered a voucher to enable poor women to access family planning services at franchised facilities. This study analyzes service trends and voucher client demographics and estimates the contribution of the program to increasing contraceptive prevalence in Uganda, using the Impact 2 model developed by Marie Stopes International. Between March 2011 and December 2014, 330,826 women received a family planning service using the voucher, of which 70% of voucher clients chose an implant and 25% chose an intrauterine device. The median age of voucher users was 28 years; 79% had no education or only a primary education; and 48% reported they were unemployed or a housewife. We estimated that by 2014, 280,000 of the approximately 8,600,000 women of reproductive age in Uganda were using a contraceptive method provided by the program and that 120,000 of the clients were "additional users" of contraception, contributing 1.4 percentage points to the national modern contraceptive prevalence rate. The combination of family planning vouchers and a franchise-based quality improvement initiative can leverage existing private health infrastructure to substantially expand family planning access and choice for disadvantaged populations and potentially improve contraceptive prevalence when scaled nationally. © Bellows et al.

  6. Increasing Contraceptive Access for Hard-to-Reach Populations With Vouchers and Social Franchising in Uganda

    Science.gov (United States)

    Bellows, Benjamin; Mackay, Anna; Dingle, Antonia; Tuyiragize, Richard; Nnyombi, William; Dasgupta, Aisha

    2017-01-01

    ABSTRACT From 2001 to 2011, modern contraceptive prevalence in Uganda increased from 18% to 26%. However, modern method use, in particular use of long-acting reversible contraceptives (LARCs) and permanent methods (PMs), remained low. In the 2011 Uganda Demographic and Health Survey, only 1 of 5 married women used a LARC or PM even though 34% indicated an unmet need for contraception. Between 2011 and 2014, a social franchise and family planning voucher program, supporting 400 private facilities to provide family planning counseling and broaden contraceptive choice by adding LARCs and PMs to the service mix, offered a voucher to enable poor women to access family planning services at franchised facilities. This study analyzes service trends and voucher client demographics and estimates the contribution of the program to increasing contraceptive prevalence in Uganda, using the Impact 2 model developed by Marie Stopes International. Between March 2011 and December 2014, 330,826 women received a family planning service using the voucher, of which 70% of voucher clients chose an implant and 25% chose an intrauterine device. The median age of voucher users was 28 years; 79% had no education or only a primary education; and 48% reported they were unemployed or a housewife. We estimated that by 2014, 280,000 of the approximately 8,600,000 women of reproductive age in Uganda were using a contraceptive method provided by the program and that 120,000 of the clients were “additional users” of contraception, contributing 1.4 percentage points to the national modern contraceptive prevalence rate. The combination of family planning vouchers and a franchise-based quality improvement initiative can leverage existing private health infrastructure to substantially expand family planning access and choice for disadvantaged populations and potentially improve contraceptive prevalence when scaled nationally. PMID:28963175

  7. Population-based geographic access to parent and satellite National Cancer Institute Cancer Center Facilities.

    Science.gov (United States)

    Onega, Tracy; Alford-Teaster, Jennifer; Wang, Fahui

    2017-09-01

    Satellite facilities of National Cancer Institute (NCI) cancer centers have expanded their regional footprints. This study characterized geographic access to parent and satellite NCI cancer center facilities nationally overall and by sociodemographics. Parent and satellite NCI cancer center facilities, which were geocoded in ArcGIS, were ascertained. Travel times from every census tract in the continental United States and Hawaii to the nearest parent and satellite facilities were calculated. Census-based population attributes were used to characterize measures of geographic access for sociodemographic groups. From the 62 NCI cancer centers providing clinical care in 2014, 76 unique parent locations and 211 satellite locations were mapped. The overall proportion of the population within 60 minutes of a facility was 22% for parent facilities and 32.7% for satellite facilities. When satellites were included for potential access, the proportion of some racial groups for which a satellite was the closest NCI cancer center facility increased notably (Native Americans, 22.6% with parent facilities and 39.7% with satellite facilities; whites, 34.8% with parent facilities and 50.3% with satellite facilities; and Asians, 40.0% with parent facilities and 54.0% with satellite facilities), with less marked increases for Hispanic and black populations. Rural populations of all categories had dramatically low proportions living within 60 minutes of an NCI cancer center facility of any type (1.0%-6.6%). Approximately 14% of the population (n = 43,033,310) lived more than 180 minutes from a parent or satellite facility, and most of these individuals were Native Americans and/or rural residents (37% of Native Americans and 41.7% of isolated rural residents). Racial/ethnic and rural populations showed markedly improved geographic access to NCI cancer center care when satellite facilities were included. Cancer 2017;123:3305-11. © 2017 American Cancer Society. © 2017 American

  8. A spatial ecosystem and populations dynamics model (SEAPODYM) Modeling of tuna and tuna-like populations

    Science.gov (United States)

    Lehodey, Patrick; Senina, Inna; Murtugudde, Raghu

    2008-09-01

    An enhanced version of the spatial ecosystem and population dynamics model SEAPODYM is presented to describe spatial dynamics of tuna and tuna-like species in the Pacific Ocean at monthly resolution over 1° grid-boxes. The simulations are driven by a bio-physical environment predicted from a coupled ocean physical-biogeochemical model. This new version of SEAPODYM includes expanded definitions of habitat indices, movements, and natural mortality based on empirical evidences. A thermal habitat of tuna species is derived from an individual heat budget model. The feeding habitat is computed according to the accessibility of tuna predator cohorts to different vertically migrating and non-migrating micronekton (mid-trophic) functional groups. The spawning habitat is based on temperature and the coincidence of spawning fish with presence or absence of predators and food for larvae. The successful larval recruitment is linked to spawning stock biomass. Larvae drift with currents, while immature and adult tuna can move of their own volition, in addition to being advected by currents. A food requirement index is computed to adjust locally the natural mortality of cohorts based on food demand and accessibility to available forage components. Together these mechanisms induce bottom-up and top-down effects, and intra- (i.e. between cohorts) and inter-species interactions. The model is now fully operational for running multi-species, multi-fisheries simulations, and the structure of the model allows a validation from multiple data sources. An application with two tuna species showing different biological characteristics, skipjack ( Katsuwonus pelamis) and bigeye ( Thunnus obesus), is presented to illustrate the capacity of the model to capture many important features of spatial dynamics of these two different tuna species in the Pacific Ocean. The actual validation is presented in a companion paper describing the approach to have a rigorous mathematical parameter optimization

  9. Population genetics models of local ancestry.

    Science.gov (United States)

    Gravel, Simon

    2012-06-01

    Migrations have played an important role in shaping the genetic diversity of human populations. Understanding genomic data thus requires careful modeling of historical gene flow. Here we consider the effect of relatively recent population structure and gene flow and interpret genomes of individuals that have ancestry from multiple source populations as mosaics of segments originating from each population. This article describes general and tractable models for local ancestry patterns with a focus on the length distribution of continuous ancestry tracts and the variance in total ancestry proportions among individuals. The models offer improved agreement with Wright-Fisher simulation data when compared to the state-of-the art and can be used to infer time-dependent migration rates from multiple populations. Considering HapMap African-American (ASW) data, we find that a model with two distinct phases of "European" gene flow significantly improves the modeling of both tract lengths and ancestry variances.

  10. A qualitative study into the perceived barriers of accessing healthcare among a vulnerable population involved with a community centre in Romania.

    Science.gov (United States)

    George, Siân; Daniels, Katy; Fioratou, Evridiki

    2018-04-03

    Minority vulnerable communities, such as the European Roma, often face numerous barriers to accessing healthcare services, resulting in negative health outcomes. Both these barriers and outcomes have been reported extensively in the literature. However, reports on barriers faced by European non-Roma native communities are limited. The "Health Care Access Barriers" (HCAB) model identifies pertinent financial, structural and cognitive barriers that can be measured and potentially modified. The present study thus aims to explore the barriers to accessing healthcare for a vulnerable population of mixed ethnicity from a charity community centre in Romania, as perceived by the centre's family users and staff members, and assess whether these reflect the barriers identified from the HCAB model. Eleven community members whose children attend the centre and seven staff members working at the centre participated in face-to-face semi-structured interviews, exploring personal experiences and views on accessing healthcare. The interviews were transcribed and analysed using an initial deductive and secondary inductive approach to identify HCAB themes and other emerging themes and subthemes. Identified themes from both groups aligned with HCAB's themes of financial, structural and cognitive barriers and emergent subthemes important to the specific population were identified. Specifically, financial barriers related mostly to health insurance and bribery issues, structural barriers related mostly to service availability and accessibility, and cognitive barriers related mostly to healthcare professionals' attitudes and discrimination and the vulnerable population's lack of education and health literacy. A unique theme of psychological barriers emerged from both groups with associated subthemes of mistrust, hopelessness, fear and anxiety of this vulnerable population. The current study highlights healthcare access barriers to a vulnerable non-Roma native population involved with a

  11. Access to drinking water and health of populations in Sub-Saharan Africa.

    Science.gov (United States)

    Ntouda, Julien; Sikodf, Fondo; Ibrahim, Mohamadou; Abba, Ibrahim

    2013-01-01

    Water is at the center of the plant and animal life, the foundation upon which the health of human settlement and development of civilizations rely on. In tropical regions, 80% of diseases are transmitted either by germs in the water, or by vectors staying in it. In Sub-Saharan Africa, statistics show particularly high levels of unmet needs of populations in access to drinking water in a context of socioeconomic development. For this purpose, this study aims to determine the influence of access to drinking water on the health of populations in Sub-Saharan Africa. Using data from Demographic and Health Surveys (DHS) from Cameroon, Senegal and Chad, it is clear from the descriptive analysis that 60% (Cameroon), and 59% (Chad) of the cases of childhood diarrhea in these two countries are due to the consumption of dirty water. In terms of explanatory analysis, we note that when a household in Cameroon, Senegal or Chad does not have access to drinking water, children under 5 years old residing there are respectively 1.29, 1.27 and 1.03 times more likely to have diarrhea than those residing in households with easy access to drinking water. In view of these results, it is recommended to increase access to drinking water in particular by reducing disparities between the rich and poor people. Copyright © 2013 Académie des sciences. All rights reserved.

  12. "Open Access" Requires Clarification: Medical Journal Publication Models Evolve.

    Science.gov (United States)

    Lubowitz, James H; Brand, Jefferson C; Rossi, Michael J; Provencher, Matthew T

    2017-03-01

    While Arthroscopy journal is a traditional subscription model journal, our companion journal Arthroscopy Techniques is "open access." We used to believe open access simply meant online and free of charge. However, while open-access journals are free to readers, in 2017 authors must make a greater sacrifice in the form of an article-processing charge (APC). Again, while this does not apply to Arthroscopy, the APC will apply to Arthroscopy Techniques. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  13. Statistical Models of Adaptive Immune populations

    Science.gov (United States)

    Sethna, Zachary; Callan, Curtis; Walczak, Aleksandra; Mora, Thierry

    The availability of large (104-106 sequences) datasets of B or T cell populations from a single individual allows reliable fitting of complex statistical models for naïve generation, somatic selection, and hypermutation. It is crucial to utilize a probabilistic/informational approach when modeling these populations. The inferred probability distributions allow for population characterization, calculation of probability distributions of various hidden variables (e.g. number of insertions), as well as statistical properties of the distribution itself (e.g. entropy). In particular, the differences between the T cell populations of embryonic and mature mice will be examined as a case study. Comparing these populations, as well as proposed mixed populations, provides a concrete exercise in model creation, comparison, choice, and validation.

  14. Spatial analysis of cattle and shoat population in Ethiopia: growth trend, distribution and market access.

    Science.gov (United States)

    Leta, Samson; Mesele, Frehiwot

    2014-01-01

    The livestock subsector has an enormous contribution to Ethiopia's national economy and livelihoods of many Ethiopians. The subsector contributes about 16.5% of the national Gross Domestic Product (GDP) and 35.6% of the agricultural GDP. It also contributes 15% of export earnings and 30% of agricultural employment. The livestock subsector currently support and sustain livelihoods for 80% of all rural population. The GDP of livestock related activities valued at 59 billion birr. Ethiopian livestock population trends, distribution and marketing vary considerably across space and time due to a variety of reasons. This study was aimed to assess cattle and shoat population growth trend, distribution and their access to market. Regression analysis was used to assess the cattle and shoat population growth trend and Geographic Information Systems (GIS) techniques were used to determine the spatial distribution of cattle and shoats, and their relative access to market. The data sets used are agricultural census (2001/02) and annual CSA agricultural sample survey (1995/96 to 2012/13). In the past eighteen years, the livestock population namely cattle, sheep and goat grew from 54.5 million to over 103.5 million with average annual increment of 3.4 million. The current average national cattle, sheep and goat population per km(2) are estimated to be 71, 33 and 29 respectively (excluding Addis Ababa, Afar and Somali regions). From the total livestock population the country owns about 46% cattle, 43% sheep and 40% goats are reared within 10 km radius from major livestock market centres and all-weather roads. On the other hand, three fourth of the country's land mass which comprises 15% of the cattle, 20% of the sheep and 21% of goat population is not accessible to market (greater than 30 km from major livestock market centres). It is found that the central highland regions account for the largest share of livestock population and also more accessible to market. Defining the

  15. Access to health-care in Canadian immigrants: a longitudinal study of the National Population Health Survey.

    Science.gov (United States)

    Setia, Maninder Singh; Quesnel-Vallee, Amelie; Abrahamowicz, Michal; Tousignant, Pierre; Lynch, John

    2011-01-01

    Immigrants often lose their health advantage as they start adapting to the ways of the new society. Having access to care when it is needed is one way that individuals can maintain their health. We assessed the healthcare access in Canadian immigrants and the socioeconomic factors associated with access over a 12-year period. We compared two measures of healthcare access (having a regular doctor and reporting an unmet healthcare need in the past 12 months) among immigrants and Canadian-born men and women, aged more than 18 years. We applied a logistic random effects model to evaluate these outcomes separately, in 3081 males and 4187 females from the National Population Health Survey (1994-2006). Adjusting for all covariates, immigrant men and women (white and non-white) had similar odds of having a regular doctor than the Canadian-born individuals (white immigrants: males OR: 1.32, 95% C.I.: 0.89-1.94, females OR: 1.14, 95% C.I.: 0.78-1.66; non-white immigrants: males OR: 1.28, 95% C.I.: 0.73-2.23, females OR: 1.23, 95% C.I.: 0.64-2.36). Interestingly, non-white immigrant women had significantly fewer unmet health needs (OR: 0.32, 95% C.I.: 0.17-0.59). Among immigrants, time since immigration was associated with having access to a regular doctor (OR per year: 1.02, 95% C.I.: 1.00-1.04). Visible minority female immigrants were least likely to report an unmet healthcare need. In general, there is little evidence that immigrants have worse access to health-care than the Canadian-born population. © 2010 Blackwell Publishing Ltd.

  16. Design and Implementation of Linux Access Control Model

    Institute of Scientific and Technical Information of China (English)

    Wei Xiaomeng; Wu Yongbin; Zhuo Jingchuan; Wang Jianyun; Haliqian Mayibula

    2017-01-01

    In this paper,the design and implementation of an access control model for Linux system are discussed in detail. The design is based on the RBAC model and combines with the inherent characteristics of the Linux system,and the support for the process and role transition is added.The core idea of the model is that the file is divided into different categories,and access authority of every category is distributed to several roles.Then,roles are assigned to users of the system,and the role of the user can be transited from one to another by running the executable file.

  17. Perturbation analysis of nonlinear matrix population models

    Directory of Open Access Journals (Sweden)

    Hal Caswell

    2008-03-01

    Full Text Available Perturbation analysis examines the response of a model to changes in its parameters. It is commonly applied to population growth rates calculated from linear models, but there has been no general approach to the analysis of nonlinear models. Nonlinearities in demographic models may arise due to density-dependence, frequency-dependence (in 2-sex models, feedback through the environment or the economy, and recruitment subsidy due to immigration, or from the scaling inherent in calculations of proportional population structure. This paper uses matrix calculus to derive the sensitivity and elasticity of equilibria, cycles, ratios (e.g. dependency ratios, age averages and variances, temporal averages and variances, life expectancies, and population growth rates, for both age-classified and stage-classified models. Examples are presented, applying the results to both human and non-human populations.

  18. Common data model access; a unified layer to access data from data analysis point of view

    International Nuclear Information System (INIS)

    Poirier, S.; Buteau, A.; Ounsy, M.; Rodriguez, C.; Hauser, N.; Lam, T.; Xiong, N.

    2012-01-01

    For almost 20 years, the scientific community of neutron and synchrotron institutes have been dreaming of a common data format for exchanging experimental results and applications for reducing and analyzing the data. Using HDF5 as a data container has become the standard in many facilities. The big issue is the standardization of the data organization (schema) within the HDF5 container. By introducing a new level of indirection for data access, the Common-Data-Model-Access (CDMA) framework proposes a solution and allows separation of responsibilities between data reduction developers and the institute. Data reduction developers are responsible for data reduction code; the institute provides a plug-in to access the data. The CDMA is a core API that accesses data through a data format plug-in mechanism and scientific application definitions (sets of keywords) coming from a consensus between scientists and institutes. Using a innovative 'mapping' system between application definitions and physical data organizations, the CDMA allows data reduction application development independent of the data file container AND schema. Each institute develops a data access plug-in for its own data file formats along with the mapping between application definitions and its data files. Thus data reduction applications can be developed from a strictly scientific point of view and are immediately able to process data acquired from several institutes. (authors)

  19. Kinetic Model of Growth of Arthropoda Populations

    Science.gov (United States)

    Ershov, Yu. A.; Kuznetsov, M. A.

    2018-05-01

    Kinetic equations were derived for calculating the growth of crustacean populations ( Crustacea) based on the biological growth model suggested earlier using shrimp ( Caridea) populations as an example. The development cycle of successive stages for populations can be represented in the form of quasi-chemical equations. The kinetic equations that describe the development cycle of crustaceans allow quantitative prediction of the development of populations depending on conditions. In contrast to extrapolation-simulation models, in the developed kinetic model of biological growth the kinetic parameters are the experimental characteristics of population growth. Verification and parametric identification of the developed model on the basis of the experimental data showed agreement with experiment within the error of the measurement technique.

  20. Enabling Accessibility Through Model-Based User Interface Development.

    Science.gov (United States)

    Ziegler, Daniel; Peissner, Matthias

    2017-01-01

    Adaptive user interfaces (AUIs) can increase the accessibility of interactive systems. They provide personalized display and interaction modes to fit individual user needs. Most AUI approaches rely on model-based development, which is considered relatively demanding. This paper explores strategies to make model-based development more attractive for mainstream developers.

  1. An intelligent trust-based access control model for affective ...

    African Journals Online (AJOL)

    In this study, a fuzzy expert system Trust-Based Access Control (TBAC) model for improving the Quality of crowdsourcing using emotional affective computing is presented. This model takes into consideration a pre-processing module consisting of three inputs such as crowd-workers category, trust metric and emotional ...

  2. New partnerships and business models for facilitating energy access

    International Nuclear Information System (INIS)

    Chaurey, Akanksha; Krithika, P.R.; Palit, Debajit; Rakesh, Smita; Sovacool, Benjamin K.

    2012-01-01

    Twenty years since the Rio Summit, the global community is still struggling to develop a world with universal access to sustainable energy services. The discussion on energy and its linkages with sustainable development is at the heart of the debate in achieving the Millennium Development Goals (MDGs). This paper discusses the role of innovations in terms of partnerships and business models to enhance energy access, especially for those living at the so-called bottom of pyramid. The role of innovative energy options and policy choices that enable overall operationalization of energy access in developing countries as well as new forms of partnerships and innovative mechanisms that are based on established success, replicability and potential for scaling up has been examined through two case-studies, namely the Lighting a Billion Lives project and India's National Rural Electrification Programme. This paper suggests the need for new forms of public and private sector partnerships, especially the pro-poor ones that are effective in enhancing energy access. - Highlights: ► We analyze the role of new partnerships and innovations in energy access. ► Emerging context of 5Ps in delivery of energy access is used for this analysis. ► LaBL and India's Rural Electrification programme used as examples. ► We recommend the need for pro-poor PPP for enhancing energy access.

  3. Structured population models in biology and epidemiology

    CERN Document Server

    Ruan, Shigui

    2008-01-01

    This book consists of six chapters written by leading researchers in mathematical biology. These chapters present recent and important developments in the study of structured population models in biology and epidemiology. Topics include population models structured by age, size, and spatial position; size-structured models for metapopulations, macroparasitc diseases, and prion proliferation; models for transmission of microparasites between host populations living on non-coincident spatial domains; spatiotemporal patterns of disease spread; method of aggregation of variables in population dynamics; and biofilm models. It is suitable as a textbook for a mathematical biology course or a summer school at the advanced undergraduate and graduate level. It can also serve as a reference book for researchers looking for either interesting and specific problems to work on or useful techniques and discussions of some particular problems.

  4. ACCESS AND USE OF HEALTH SERVICES BY GYPSY POPULATION: A SYSTEMATIC REVIEW

    Directory of Open Access Journals (Sweden)

    Ana Cláudia Conceição da Silva

    2016-06-01

    Full Text Available Study aimed to characterize the studies on access and use of health services by the Roma population. A systematic review was performed by searching for articles from databases OvidSP/Medline, ProQuest, Web of Science and LILACS, between 2003 and 2013. Initially, 115 citations were selected: (51 Medline, (17 ProQuest, ( 47 Web of Science, (0 Lilacs. After thorough reading, 10 articles were selected which were related to access and health of Roma population. Many studies seemed to meet inclusion criteria by reading the title and abstract, but after thorough reading they did not meet the requirements. All are in English idiom. Most of the UK in the period of 2012-1013, quantitative studies. They presented varied methods, without methodological rigor and detail, with unrepresentative samples and little comparability findings.

  5. Measuring and Comparing Hospital Accessibility for Palm Beach County's Elderly and Nonelderly Populations During a Hurricane.

    Science.gov (United States)

    Prasad, Shivangi

    2017-09-18

    To determine whether, during a hurricane, geographic accessibility to hospitals with emergency care is compromised disproportionately for the elderly than for the nonelderly. The locations of hospitals with emergency health care and a subset of those hospitals functional during a hurricane were compared with the distribution of the elderly population at the block group level in Palm Beach County, Florida. Geographic Information Systems (GIS) proximity analysis (minimum distance to closest hospital) and cumulative distribution functions were used to measure and compare hospital accessibility during normal and hurricane conditions for the elderly and nonelderly populations. Accessibility to closest functional hospital during a hurricane was compromised disproportionately for the elderly. Geographic accessibility to emergency health care is compromised disproportionately for the elderly in Palm Beach County. Compounding the risk is the likelihood of the elderly experiencing a greater health care need during a hurricane. This poses a community public health crisis and calls for effective and collaborative planning between health professionals and disaster planners to address the health care needs of the elderly. (Disaster Med Public Health Preparedness. 2017;page 1 of 5).

  6. Accessibility

    DEFF Research Database (Denmark)

    Brooks, Anthony Lewis

    2017-01-01

    This contribution is timely as it addresses accessibility in regards system hardware and software aligned with introduction of the Twenty-First Century Communications and Video Accessibility Act (CVAA) and adjoined game industry waiver that comes into force January 2017. This is an act created...... by the USA Federal Communications Commission (FCC) to increase the access of persons with disabilities to modern communications, and for other purposes. The act impacts advanced communications services and products including text messaging; e-mail; instant messaging; video communications; browsers; game...... platforms; and games software. However, the CVAA has no legal status in the EU. This text succinctly introduces and questions implications, impact, and wider adoption. By presenting the full CVAA and game industry waiver the text targets to motivate discussions and further publications on the subject...

  7. Integrity Based Access Control Model for Multilevel XML Document

    Institute of Scientific and Technical Information of China (English)

    HONG Fan; FENG Xue-bin; HUANO Zhi; ZHENG Ming-hui

    2008-01-01

    XML's increasing popularity highlights the security demand for XML documents. A mandatory access control model for XML document is presented on the basis of investigation of the function dependency of XML documents and discussion of the integrity properties of multilevel XML document. Then, the algorithms for decomposition/recovery multilevel XML document into/from single level document are given, and the manipulation rules for typical operations of XQuery and XUpdate: QUERY, INSERT,UPDATE, and REMOVE, are elaborated. The multilevel XML document access model can meet the requirement of sensitive information processing application.

  8. Bivalves: From individual to population modelling

    NARCIS (Netherlands)

    Saraiva, S.; van der Meer, J.; Kooijman, S.A.L.M.

    2014-01-01

    An individual based population model for bivalves was designed, built and tested in a 0D approach, to simulate the population dynamics of a mussel bed located in an intertidal area. The processes at the individual level were simulated following the dynamic energy budget theory, whereas initial egg

  9. Modeling the population dynamics of Pacific yew.

    Science.gov (United States)

    Richard T. Busing; Thomas A. Spies

    1995-01-01

    A study of Pacific yew (Taxus brevifolia Nutt.) population dynamics in the mountains of western Oregon and Washington was based on a combination of long-term population data and computer modeling. Rates of growth and mortality were low in mature and old-growth forest stands. Diameter growth at breast height ranged from 0 to 3 centimeters per decade...

  10. Estimating spatial accessibility to facilities on the regional scale: an extended commuting-based interaction potential model

    Directory of Open Access Journals (Sweden)

    Charreire Hélène

    2011-01-01

    Full Text Available Abstract Background There is growing interest in the study of the relationships between individual health-related behaviours (e.g. food intake and physical activity and measurements of spatial accessibility to the associated facilities (e.g. food outlets and sport facilities. The aim of this study is to propose measurements of spatial accessibility to facilities on the regional scale, using aggregated data. We first used a potential accessibility model that partly makes it possible to overcome the limitations of the most frequently used indices such as the count of opportunities within a given neighbourhood. We then propose an extended model in order to take into account both home and work-based accessibility for a commuting population. Results Potential accessibility estimation provides a very different picture of the accessibility levels experienced by the population than the more classical "number of opportunities per census tract" index. The extended model for commuters increases the overall accessibility levels but this increase differs according to the urbanisation level. Strongest increases are observed in some rural municipalities with initial low accessibility levels. Distance to major urban poles seems to play an essential role. Conclusions Accessibility is a multi-dimensional concept that should integrate some aspects of travel behaviour. Our work supports the evidence that the choice of appropriate accessibility indices including both residential and non-residential environmental features is necessary. Such models have potential implications for providing relevant information to policy-makers in the field of public health.

  11. A consumer register: an acceptable and cost-effective alternative for accessing patient populations

    Directory of Open Access Journals (Sweden)

    Jamie Bryant

    2016-10-01

    Full Text Available Abstract Background Population-based registries are increasingly used to recruit patient samples for research, however, they have several limitations including low consent and participation rates, and potential selection bias. To improve access to samples for research, the utility of a new model of recruitment termed the ‘Consumer Register’, that allows for direct patient recruitment from hospitals, was examined. This paper reports: (i consent rates onto the register; (ii preferred methods and frequency of contact; and (iii the feasibility of establishing the register, including: (a cost per person recruited to the register; (b the differential cost and consent rates of volunteer versus paid data collectors; and (c participant completion rates. Methods A cross-sectional survey was conducted in five outpatient clinics in Australia. Patients were approached by volunteers or paid data collectors and asked to complete a touch-screen electronic survey. Consenting individuals were asked to indicate their willingness and preferences for enrolment onto a research register. Descriptive statistics were used to examine patient preferences and linear regression used to model the success of volunteer versus paid data collectors. The opportunity and financial costs of establishing the register were calculated. Results A total of 1947 patients (80.6 % consented to complete the survey, of which, 1486 (76.3 % completed the questionnaire. Of the completers, the majority (69.4 %, or 1032 participants were willing to be listed on the register and preferred to be contacted by email (50.3 %. Almost 39 % of completers were willing to be contacted three or more times in a 12 month period. The annual opportunity cost of resources consumed by the register was valued at $37,187, giving an opportunity cost per person recruited to the register of $36. After amortising fixed costs, the annual financial outlay was $23,004 or $22 per person recruited to the

  12. Population-expression models of immune response

    International Nuclear Information System (INIS)

    Stromberg, Sean P; Antia, Rustom; Nemenman, Ilya

    2013-01-01

    The immune response to a pathogen has two basic features. The first is the expansion of a few pathogen-specific cells to form a population large enough to control the pathogen. The second is the process of differentiation of cells from an initial naive phenotype to an effector phenotype which controls the pathogen, and subsequently to a memory phenotype that is maintained and responsible for long-term protection. The expansion and the differentiation have been considered largely independently. Changes in cell populations are typically described using ecologically based ordinary differential equation models. In contrast, differentiation of single cells is studied within systems biology and is frequently modeled by considering changes in gene and protein expression in individual cells. Recent advances in experimental systems biology make available for the first time data to allow the coupling of population and high dimensional expression data of immune cells during infections. Here we describe and develop population-expression models which integrate these two processes into systems biology on the multicellular level. When translated into mathematical equations, these models result in non-conservative, non-local advection-diffusion equations. We describe situations where the population-expression approach can make correct inference from data while previous modeling approaches based on common simplifying assumptions would fail. We also explore how model reduction techniques can be used to build population-expression models, minimizing the complexity of the model while keeping the essential features of the system. While we consider problems in immunology in this paper, we expect population-expression models to be more broadly applicable. (paper)

  13. Modeling Accessibility of Screening and Treatment Facilities for Older Adults using Transportation Networks.

    Science.gov (United States)

    Zhang, Qiuyi; Northridge, Mary E; Jin, Zhu; Metcalf, Sara S

    2018-04-01

    Increased lifespans and population growth have resulted in an older U.S. society that must reckon with the complex oral health needs that arise as adults age. Understanding accessibility to screening and treatment facilities for older adults is necessary in order to provide them with preventive and restorative services. This study uses an agent-based model to examine the accessibility of screening and treatment facilities via transportation networks for older adults living in the neighborhoods of northern Manhattan, New York City. Older adults are simulated as socioeconomically distinct agents who move along a GIS-based transportation network using transportation modes that mediate their access to screening and treatment facilities. This simulation model includes four types of mobile agents as a simplifying assumption: walk, by car, by bus, or by van (i.e., a form of transportation assistance for older adults). These mobile agents follow particular routes: older adults who travel by car, bus, and van follow street roads, whereas pedestrians follow walkways. The model enables the user to focus on one neighborhood at a time for analysis. The spatial dimension of an older adult's accessibility to screening and treatment facilities is simulated through the travel costs (indicated by travel time or distance) incurred in the GIS-based model environment, where lower travel costs to screening and treatment facilities imply better access. This model provides a framework for representing health-seeking behavior that is contextualized by a transportation network in a GIS environment.

  14. Doula Services Within a Healthy Start Program: Increasing Access for an Underserved Population.

    Science.gov (United States)

    Thomas, Mary-Powel; Ammann, Gabriela; Brazier, Ellen; Noyes, Philip; Maybank, Aletha

    2017-12-01

    Women of color in the United States, particularly in high-poverty neighborhoods, experience high rates of poor birth outcomes, including cesarean section, preterm birth, low birthweight, and infant mortality. Doula care has been linked to improvements in many perinatal outcomes, but women of color and low-income women often face barriers in accessing doula support. To address this issue, the New York City Department of Health and Mental Hygiene's Healthy Start Brooklyn introduced the By My Side Birth Support Program in 2010. The goal was to complement other maternal home-visiting programs by providing doula support during labor and birth, along with prenatal and postpartum visits. Between 2010 and 2015, 489 infants were born to women enrolled in the program. Data indicate that By My Side is a promising model of support for Healthy Start projects nationwide. Compared to the project area, program participants had lower rates of preterm birth (6.3 vs. 12.4%, p < 0.001) and low birthweight (6.5 vs. 11.1%, p = 0.001); however, rates of cesarean birth did not differ significantly (33.5 vs. 36.9%, p = 0.122). Further research is needed to explore possible reasons for this finding, and to examine the influence of doula support on birth outcomes among populations with high rates of chronic disease and stressors such as poverty, racism, and exposure to violence. However, feedback from participants indicates that doula support is highly valued and helps give women a voice in consequential childbirth decisions. Available evidence suggests that doula services may be an important component of an effort to address birth inequities.

  15. [Improve the accessibility of essential drugs for the populations of one medical region in Burkina Faso].

    Science.gov (United States)

    Ridde, Valéry; Nitièma, Abdoulaye P; Dadjoari, Moussa

    2005-01-01

    Despite the formulation of the Bamako initiative in 1992 in Burkina Faso, not until 2001 and the launching of a project by a nongovernmental organization was the policy really implemented in a region of the country. One of the goals of this policy is to improve access to health care by using generic essential drugs. The objective of this article is to summarize the results of the evaluation of the project's ability to improve the population's access to drugs. The project lasted three years (2001-2003) and the interventions took place in 41 basic health centres of three districts. According to WHO, improving access to drugs requires consideration of four essential factors: rational use, affordable prices, financial viability, and effectiveness of the distribution. The average number of drugs prescribed per prescription sheet (n = 1061) was 2.4; 93% of the drugs were prescribed by their generic name (international non-proprietary names); 44% of infant diarrheas were treated with oral rehydration salt. National drug prices were respected but not the directives aiming at exempting from payment or subsidizing certain population sub-groups (children, indigents). The average annual cash flow of the basic health centres was 1.2 million F CFA and it increased by 854% compared to the beginning of the project. The cost-recovery scheme for administrative expenses was 106%. The average annual availability of the 10 essential drugs was 89%. Utilization rates increased (0.13 in 1999 to 0.21 in 2003) but not significantly differently than in other basic health centres of the area not supported by the project (p = 0.084). The project succeeded in improving access to these drugs for the overall population but not for the worst-off. The drugs are now geographically available for all and financially accessible for those who can afford to pay. The intervention strategy supported the sustainability of the project's activities but much remains to be done to provide the poorest with

  16. Dental Therapists as New Oral Health Practitioners: Increasing Access for Underserved Populations.

    Science.gov (United States)

    Brickle, Colleen M; Self, Karl D

    2017-09-01

    The development of dental therapy in the U.S. grew from a desire to find a workforce solution for increasing access to oral health care. Worldwide, the research that supports the value of dental therapy is considerable. Introduction of educational programs in the U.S. drew on the experiences of programs in New Zealand, Australia, Canada, and the United Kingdom, with Alaska tribal communities introducing dental health aide therapists in 2003 and Minnesota authorizing dental therapy in 2009. Currently, two additional states have authorized dental therapy, and two additional tribal communities are pursuing the use of dental therapists. In all cases, the care provided by dental therapists is focused on communities and populations who experience oral health care disparities and have historically had difficulties in accessing care. This article examines the development and implementation of the dental therapy profession in the U.S. An in-depth look at dental therapy programs in Minnesota and the practice of dental therapy in Minnesota provides insight into the early implementation of this emerging profession. Initial results indicate that the addition of dental therapists to the oral health care team is increasing access to quality oral health care for underserved populations. As evidence of dental therapy's success continues to grow, mid-level dental workforce legislation is likely to be introduced by oral health advocates in other states. This article was written as part of the project "Advancing Dental Education in the 21 st Century."

  17. Permanent genetic access to transiently active neurons via TRAP: targeted recombination in active populations.

    Science.gov (United States)

    Guenthner, Casey J; Miyamichi, Kazunari; Yang, Helen H; Heller, H Craig; Luo, Liqun

    2013-06-05

    Targeting genetically encoded tools for neural circuit dissection to relevant cellular populations is a major challenge in neurobiology. We developed an approach, targeted recombination in active populations (TRAP), to obtain genetic access to neurons that were activated by defined stimuli. This method utilizes mice in which the tamoxifen-dependent recombinase CreER(T2) is expressed in an activity-dependent manner from the loci of the immediate early genes Arc and Fos. Active cells that express CreER(T2) can only undergo recombination when tamoxifen is present, allowing genetic access to neurons that are active during a time window of less than 12 hr. We show that TRAP can provide selective access to neurons activated by specific somatosensory, visual, and auditory stimuli and by experience in a novel environment. When combined with tools for labeling, tracing, recording, and manipulating neurons, TRAP offers a powerful approach for understanding how the brain processes information and generates behavior. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Bivalves: From individual to population modelling

    Science.gov (United States)

    Saraiva, S.; van der Meer, J.; Kooijman, S. A. L. M.; Ruardij, P.

    2014-11-01

    An individual based population model for bivalves was designed, built and tested in a 0D approach, to simulate the population dynamics of a mussel bed located in an intertidal area. The processes at the individual level were simulated following the dynamic energy budget theory, whereas initial egg mortality, background mortality, food competition, and predation (including cannibalism) were additional population processes. Model properties were studied through the analysis of theoretical scenarios and by simulation of different mortality parameter combinations in a realistic setup, imposing environmental measurements. Realistic criteria were applied to narrow down the possible combination of parameter values. Field observations obtained in the long-term and multi-station monitoring program were compared with the model scenarios. The realistically selected modeling scenarios were able to reproduce reasonably the timing of some peaks in the individual abundances in the mussel bed and its size distribution but the number of individuals was not well predicted. The results suggest that the mortality in the early life stages (egg and larvae) plays an important role in population dynamics, either by initial egg mortality, larvae dispersion, settlement failure or shrimp predation. Future steps include the coupling of the population model with a hydrodynamic and biogeochemical model to improve the simulation of egg/larvae dispersion, settlement probability, food transport and also to simulate the feedback of the organisms' activity on the water column properties, which will result in an improvement of the food quantity and quality characterization.

  19. Social Networks and Health: Understanding the Nuances of Healthcare Access between Urban and Rural Populations.

    Science.gov (United States)

    Amoah, Padmore Adusei; Edusei, Joseph; Amuzu, David

    2018-05-13

    Communities and individuals in many sub-Saharan African countries often face limited access to healthcare. Hence, many rely on social networks to enhance their chances for adequate health care. While this knowledge is well-established, little is known about the nuances of how different population groups activate these networks to improve access to healthcare. This paper examines how rural and urban dwellers in the Ashanti Region in Ghana distinctively and systematically activate their social networks to enhance access to healthcare. It uses a qualitative cross-sectional design, with in-depth interviews of 79 primary participants (28 urban and 51 rural residents) in addition to the views of eight community leaders and eight health personnel. It was discovered that both intimate and distanced social networks for healthcare are activated at different periods by rural and urban residents. Four main stages of social networks activation, comprising different individuals and groups were observed among rural and urban dwellers. Among both groups, physical proximity, privacy, trust and sense of fairness, socio-cultural meaning attached to health problems, and perceived knowledge and other resources (mainly money) held in specific networks inherently influenced social network activation. The paper posits that a critical analysis of social networks may help to tailor policy contents to individuals and groups with limited access to healthcare.

  20. Location Aggregation of Spatial Population CTMC Models

    Directory of Open Access Journals (Sweden)

    Luca Bortolussi

    2016-10-01

    Full Text Available In this paper we focus on spatial Markov population models, describing the stochastic evolution of populations of agents, explicitly modelling their spatial distribution, representing space as a discrete, finite graph. More specifically, we present a heuristic approach to aggregating spatial locations, which is designed to preserve the dynamical behaviour of the model whilst reducing the computational cost of analysis. Our approach combines stochastic approximation ideas (moment closure, linear noise, with computational statistics (spectral clustering to obtain an efficient aggregation, which is experimentally shown to be reasonably accurate on two case studies: an instance of epidemic spreading and a London bike sharing scenario.

  1. Techniques to Access Databases and Integrate Data for Hydrologic Modeling

    International Nuclear Information System (INIS)

    Whelan, Gene; Tenney, Nathan D.; Pelton, Mitchell A.; Coleman, Andre M.; Ward, Duane L.; Droppo, James G.; Meyer, Philip D.; Dorow, Kevin E.; Taira, Randal Y.

    2009-01-01

    This document addresses techniques to access and integrate data for defining site-specific conditions and behaviors associated with ground-water and surface-water radionuclide transport applicable to U.S. Nuclear Regulatory Commission reviews. Environmental models typically require input data from multiple internal and external sources that may include, but are not limited to, stream and rainfall gage data, meteorological data, hydrogeological data, habitat data, and biological data. These data may be retrieved from a variety of organizations (e.g., federal, state, and regional) and source types (e.g., HTTP, FTP, and databases). Available data sources relevant to hydrologic analyses for reactor licensing are identified and reviewed. The data sources described can be useful to define model inputs and parameters, including site features (e.g., watershed boundaries, stream locations, reservoirs, site topography), site properties (e.g., surface conditions, subsurface hydraulic properties, water quality), and site boundary conditions, input forcings, and extreme events (e.g., stream discharge, lake levels, precipitation, recharge, flood and drought characteristics). Available software tools for accessing established databases, retrieving the data, and integrating it with models were identified and reviewed. The emphasis in this review was on existing software products with minimal required modifications to enable their use with the FRAMES modeling framework. The ability of four of these tools to access and retrieve the identified data sources was reviewed. These four software tools were the Hydrologic Data Acquisition and Processing System (HDAPS), Integrated Water Resources Modeling System (IWRMS) External Data Harvester, Data for Environmental Modeling Environmental Data Download Tool (D4EM EDDT), and the FRAMES Internet Database Tools. The IWRMS External Data Harvester and the D4EM EDDT were identified as the most promising tools based on their ability to access and

  2. Techniques to Access Databases and Integrate Data for Hydrologic Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Whelan, Gene; Tenney, Nathan D.; Pelton, Mitchell A.; Coleman, Andre M.; Ward, Duane L.; Droppo, James G.; Meyer, Philip D.; Dorow, Kevin E.; Taira, Randal Y.

    2009-06-17

    This document addresses techniques to access and integrate data for defining site-specific conditions and behaviors associated with ground-water and surface-water radionuclide transport applicable to U.S. Nuclear Regulatory Commission reviews. Environmental models typically require input data from multiple internal and external sources that may include, but are not limited to, stream and rainfall gage data, meteorological data, hydrogeological data, habitat data, and biological data. These data may be retrieved from a variety of organizations (e.g., federal, state, and regional) and source types (e.g., HTTP, FTP, and databases). Available data sources relevant to hydrologic analyses for reactor licensing are identified and reviewed. The data sources described can be useful to define model inputs and parameters, including site features (e.g., watershed boundaries, stream locations, reservoirs, site topography), site properties (e.g., surface conditions, subsurface hydraulic properties, water quality), and site boundary conditions, input forcings, and extreme events (e.g., stream discharge, lake levels, precipitation, recharge, flood and drought characteristics). Available software tools for accessing established databases, retrieving the data, and integrating it with models were identified and reviewed. The emphasis in this review was on existing software products with minimal required modifications to enable their use with the FRAMES modeling framework. The ability of four of these tools to access and retrieve the identified data sources was reviewed. These four software tools were the Hydrologic Data Acquisition and Processing System (HDAPS), Integrated Water Resources Modeling System (IWRMS) External Data Harvester, Data for Environmental Modeling Environmental Data Download Tool (D4EM EDDT), and the FRAMES Internet Database Tools. The IWRMS External Data Harvester and the D4EM EDDT were identified as the most promising tools based on their ability to access and

  3. Reexamining microRNA site accessibility in Drosophila: a population genomics study.

    Directory of Open Access Journals (Sweden)

    Kevin Chen

    Full Text Available Kertesz et al. (Nature Genetics 2008 described PITA, a miRNA target prediction algorithm based on hybridization energy and site accessibility. In this note, we used a population genomics approach to reexamine their data and found that the PITA algorithm had lower specificity than methods based on evolutionary conservation at comparable levels of sensitivity.We also showed that deeply conserved miRNAs tend to have stronger hybridization energies to their targets than do other miRNAs. Although PITA had higher specificity in predicting targets than a naïve seed-match method, this signal was primarily due to the use of a single cutoff score for all miRNAs and to the observed correlation between conservation and hybridization energy. Overall, our results clarify the accuracy of different miRNA target prediction algorithms in Drosophila and the role of site accessibility in miRNA target prediction.

  4. Trust-Based Access Control Model from Sociological Approach in Dynamic Online Social Network Environment

    Science.gov (United States)

    Kim, Seungjoo

    2014-01-01

    There has been an explosive increase in the population of the OSN (online social network) in recent years. The OSN provides users with many opportunities to communicate among friends and family. Further, it facilitates developing new relationships with previously unknown people having similar beliefs or interests. However, the OSN can expose users to adverse effects such as privacy breaches, the disclosing of uncontrolled material, and the disseminating of false information. Traditional access control models such as MAC, DAC, and RBAC are applied to the OSN to address these problems. However, these models are not suitable for the dynamic OSN environment because user behavior in the OSN is unpredictable and static access control imposes a burden on the users to change the access control rules individually. We propose a dynamic trust-based access control for the OSN to address the problems of the traditional static access control. Moreover, we provide novel criteria to evaluate trust factors such as sociological approach and evaluate a method to calculate the dynamic trust values. The proposed method can monitor negative behavior and modify access permission levels dynamically to prevent the indiscriminate disclosure of information. PMID:25374943

  5. Trust-Based Access Control Model from Sociological Approach in Dynamic Online Social Network Environment

    Directory of Open Access Journals (Sweden)

    Seungsoo Baek

    2014-01-01

    Full Text Available There has been an explosive increase in the population of the OSN (online social network in recent years. The OSN provides users with many opportunities to communicate among friends and family. Further, it facilitates developing new relationships with previously unknown people having similar beliefs or interests. However, the OSN can expose users to adverse effects such as privacy breaches, the disclosing of uncontrolled material, and the disseminating of false information. Traditional access control models such as MAC, DAC, and RBAC are applied to the OSN to address these problems. However, these models are not suitable for the dynamic OSN environment because user behavior in the OSN is unpredictable and static access control imposes a burden on the users to change the access control rules individually. We propose a dynamic trust-based access control for the OSN to address the problems of the traditional static access control. Moreover, we provide novel criteria to evaluate trust factors such as sociological approach and evaluate a method to calculate the dynamic trust values. The proposed method can monitor negative behavior and modify access permission levels dynamically to prevent the indiscriminate disclosure of information.

  6. Coupling population dynamics with earth system models: the POPEM model.

    Science.gov (United States)

    Navarro, Andrés; Moreno, Raúl; Jiménez-Alcázar, Alfonso; Tapiador, Francisco J

    2017-09-16

    Precise modeling of CO 2 emissions is important for environmental research. This paper presents a new model of human population dynamics that can be embedded into ESMs (Earth System Models) to improve climate modeling. Through a system dynamics approach, we develop a cohort-component model that successfully simulates historical population dynamics with fine spatial resolution (about 1°×1°). The population projections are used to improve the estimates of CO 2 emissions, thus transcending the bulk approach of existing models and allowing more realistic non-linear effects to feature in the simulations. The module, dubbed POPEM (from Population Parameterization for Earth Models), is compared with current emission inventories and validated against UN aggregated data. Finally, it is shown that the module can be used to advance toward fully coupling the social and natural components of the Earth system, an emerging research path for environmental science and pollution research.

  7. Models of the solvent-accessible surface of biopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.E.

    1996-09-01

    Many biopolymers such as proteins, DNA, and RNA have been studied because they have important biomedical roles and may be good targets for therapeutic action in treating diseases. This report describes how plastic models of the solvent-accessible surface of biopolymers were made. Computer files containing sets of triangles were calculated, then used on a stereolithography machine to make the models. Small (2 in.) models were made to test whether the computer calculations were done correctly. Also, files of the type (.stl) required by any ISO 9001 rapid prototyping machine were written onto a CD-ROM for distribution to American companies.

  8. Accessing Wireless Sensor Networks Via Dynamically Reconfigurable Interaction Models

    Directory of Open Access Journals (Sweden)

    Maria Cecília Gomes

    2012-12-01

    Full Text Available The Wireless Sensor Networks (WSNs technology is already perceived as fundamental for science across many domains, since it provides a low cost solution for environment monitoring. WSNs representation via the service concept and its inclusion in Web environments, e.g. through Web services, supports particularly their open/standard access and integration. Although such Web enabled WSNs simplify data access, network parameterization and aggregation, the existing interaction models and run-time adaptation mechanisms available to clients are still scarce. Nevertheless, applications increasingly demand richer and more flexible accesses besides the traditional client/server. For instance, applications may require a streaming model in order to avoid sequential data requests, or the asynchronous notification of subscribed data through the publish/subscriber. Moreover, the possibility to automatically switch between such models at runtime allows applications to define flexible context-based data acquisition. To this extent, this paper discusses the relevance of the session and pattern abstractions on the design of a middleware prototype providing richer and dynamically reconfigurable interaction models to Web enabled WSNs.

  9. Extending AAA operational model for profile-based access control in ethernet-based Neutral Access Networks

    NARCIS (Netherlands)

    Matias, J.; Jacob, E.; Demchenko, Y.; de Laat, C.; Gommans, L.; Macías López, E.M.; Bogliolo, A.; Perry, M.; Ran, M

    2010-01-01

    Neutral Access Networks (NAN) have appeared as a new model to overcome some restrictions and lack of flexibility that are present currently in broadband access networks. NAN brings new business opportunities by opening this market to new stakeholders. Although the NAN model is accepted, there are

  10. Access Control Model for Sharing Composite Electronic Health Records

    Science.gov (United States)

    Jin, Jing; Ahn, Gail-Joon; Covington, Michael J.; Zhang, Xinwen

    The adoption of electronically formatted medical records, so called Electronic Health Records (EHRs), has become extremely important in healthcare systems to enable the exchange of medical information among stakeholders. An EHR generally consists of data with different types and sensitivity degrees which must be selectively shared based on the need-to-know principle. Security mechanisms are required to guarantee that only authorized users have access to specific portions of such critical record for legitimate purposes. In this paper, we propose a novel approach for modelling access control scheme for composite EHRs. Our model formulates the semantics and structural composition of an EHR document, from which we introduce a notion of authorized zones of the composite EHR at different granularity levels, taking into consideration of several important criteria such as data types, intended purposes and information sensitivities.

  11. Access to justice within the sustainable self-governance model

    OpenAIRE

    Stephen Tully

    2004-01-01

    Little attention has been given to the development and operation of non-state models of global governance and the extent to which they conform to principles of good governance. Focusing primarily on issues of access to justice and secondarily on the independence of such bodies from the industries which they purport to regulate, this paper argues that adjudicative mechanisms established by non-governmental organisations (NGOs) and firms may not produce outcomes which are considered 'just' by t...

  12. [Perceptions and experiences of access to health services and their utilization among the immigrant population].

    Science.gov (United States)

    Bas-Sarmiento, Pilar; Fernández-Gutiérrez, Martina; Albar-Marín, M A Jesús; García-Ramírez, Manuel

    2015-01-01

    To identify and describe the needs and problems of the immigrant population related to access and utilization of health services. A descriptive, qualitative, phenomenological study was conducted using focus groups. The study area was the county of Campo de Gibraltar (Spain), which represents the gateway to Europe for immigration from Africa. The final sample size (51 immigrants from 11 countries) was determined by theoretical saturation. A narrative analysis was conducted with QSR NVivo9 software. Immigrants' discourse showed four categories of analysis: response to a health problem, system access, knowledge of social and health resources, and health literacy needs. Responses to health problems and the route of access to the health care system differed according to some sociodemographic characteristics (nationality/culture of origin, length of residence, and economic status). In general, immigrants primarily used emergency services, hampering health promotion and prevention. The health literacy needs identified concerned language proficiency and the functioning of the health system. There is a need to promote interventions to enhance health literacy among immigrants. These interventions should take into account diversity and length of residence, and should be based on an action-participation methodology. Copyright © 2014 SESPAS. Published by Elsevier Espana. All rights reserved.

  13. Accessibility to health services in the prison population in Colombia: a public health challenge

    Directory of Open Access Journals (Sweden)

    Luz Mery Mejía O

    2010-08-01

    Full Text Available This article is the result of a product of a study elaborated with the aim of systematizing the available information related to the accessibility to the health services of the prison population in the penitentiary centers. To this end, we reviewed the literature and systematic collection of the academic available material in the principal university libraries in the city of Medellin, scientific databases and the web pages of national and international organizations that have dealt with this topic. The information was systematized considering some historical references to prisons and health, the record of experiences in some countries and the current regulations for health care in the prison population in the Colombian case. We conclude that although significant progress has been made to ensure health care for the prison population, in the prison there are still obstacles and limitations that infringe the right to health of this population. Likewise, it is evidenced that it has not been considered a public health problem in the country, which it is considered a challenge to incorporate it as such.

  14. Does decreased access to emergency departments affect patient outcomes? Analysis of acute myocardial infarction population 1996-2005.

    Science.gov (United States)

    Shen, Yu-Chu; Hsia, Renee Y

    2012-02-01

    We analyze whether decreased emergency department (ED) access results in adverse patient outcomes or changes in the patient health profile for patients with acute myocardial infarction (AMI). We merge Medicare claims, American Hospital Association annual surveys, Medicare hospital cost reports, and location information for 1995-2005. We define four ED access change categories and estimate a ZIP Code fixed-effects regression models on the following AMI outcomes: mortality rates, age, and probability of percutaneous transluminal coronary angioplasty (PTCA) on day of admission. We find a small increase in 30-day to 1-year mortality rates among patients in communities that experience a 30-minute increases, we find a substantial increase in long-term mortality rates, a shift to younger ages (suggesting that older patients die en route), and a higher probability of immediate PTCA. Most of the adverse effects disappear after the transition years. Deterioration in geographic access to ED affects a small segment of the population, and most adverse effects are transitory. Policy planners can minimize the adverse effects by providing assistance to ensure adequate capacity of remaining EDs, and facilitating the realignment of health care resources during the critical transition periods. © Health Research and Educational Trust.

  15. Comments to a polar bear population model

    OpenAIRE

    Øritsland, Nils Are

    1985-01-01

    Larsen, T. & Ugland, K. I. (Polar Research 2 n.s., 117-118) note correctly that a Leslie matrix model treats cubs and females as independent units which is not the case for polar bears. Population projections using the Leslie model with hunting mortalities added are instructive first approximations in evaluations of field data, however, and are recommended as exercises also for polar bear biologists. An APL programme for such projections is available.

  16. Inferences from Genomic Models in Stratified Populations

    DEFF Research Database (Denmark)

    Janss, Luc; de los Campos, Gustavo; Sheehan, Nuala

    2012-01-01

    Unaccounted population stratification can lead to spurious associations in genome-wide association studies (GWAS) and in this context several methods have been proposed to deal with this problem. An alternative line of research uses whole-genome random regression (WGRR) models that fit all marker...

  17. Urban search mobile platform modeling in hindered access conditions

    Science.gov (United States)

    Barankova, I. I.; Mikhailova, U. V.; Kalugina, O. B.; Barankov, V. V.

    2018-05-01

    The article explores the control system simulation and the design of the experimental model of the rescue robot mobile platform. The functional interface, a structural functional diagram of the mobile platform control unit, and a functional control scheme for the mobile platform of secure robot were modeled. The task of design a mobile platform for urban searching in hindered access conditions is realized through the use of a mechanical basis with a chassis and crawler drive, a warning device, human heat sensors and a microcontroller based on Arduino platforms.

  18. Time series sightability modeling of animal populations.

    Science.gov (United States)

    ArchMiller, Althea A; Dorazio, Robert M; St Clair, Katherine; Fieberg, John R

    2018-01-01

    Logistic regression models-or "sightability models"-fit to detection/non-detection data from marked individuals are often used to adjust for visibility bias in later detection-only surveys, with population abundance estimated using a modified Horvitz-Thompson (mHT) estimator. More recently, a model-based alternative for analyzing combined detection/non-detection and detection-only data was developed. This approach seemed promising, since it resulted in similar estimates as the mHT when applied to data from moose (Alces alces) surveys in Minnesota. More importantly, it provided a framework for developing flexible models for analyzing multiyear detection-only survey data in combination with detection/non-detection data. During initial attempts to extend the model-based approach to multiple years of detection-only data, we found that estimates of detection probabilities and population abundance were sensitive to the amount of detection-only data included in the combined (detection/non-detection and detection-only) analysis. Subsequently, we developed a robust hierarchical modeling approach where sightability model parameters are informed only by the detection/non-detection data, and we used this approach to fit a fixed-effects model (FE model) with year-specific parameters and a temporally-smoothed model (TS model) that shares information across years via random effects and a temporal spline. The abundance estimates from the TS model were more precise, with decreased interannual variability relative to the FE model and mHT abundance estimates, illustrating the potential benefits from model-based approaches that allow information to be shared across years.

  19. Estimating rural populations without access to electricity in developing countries through night-time light satellite imagery

    International Nuclear Information System (INIS)

    Doll, Christopher N.H.; Pachauri, Shonali

    2010-01-01

    A lack of access to energy and, in particular, electricity is a less obvious manifestation of poverty but arguably one of the most important. This paper investigates the extent to which electricity access can be investigated using night-time light satellite data and spatially explicit population datasets to compare electricity access between 1990 and 2000. We present here the first satellite derived estimates of rural population without access to electricity in developing countries to draw insights on issues surrounding the delivery of electricity to populations in rural areas. The paper provides additional evidence of the slow progress in expansion of energy access to households in Sub-Saharan Africa and shows how this might be ascribed in part due to the low population densities in rural areas. The fact that this is a continent with some of the lowest per-capita income levels aggravates the intrinsic difficulties associated with making the investments needed to supply electricity in areas with low population density and high dispersion. Clearly, these spatial dimensions of the distributions of the remaining unelectrified populations in the world have an impact on what options are considered the most appropriate in expanding access to these households and the relative attractiveness of decentralized options.

  20. A probabilistic model for cell population phenotyping using HCS data.

    Directory of Open Access Journals (Sweden)

    Edouard Pauwels

    Full Text Available High Content Screening (HCS platforms allow screening living cells under a wide range of experimental conditions and give access to a whole panel of cellular responses to a specific treatment. The outcome is a series of cell population images. Within these images, the heterogeneity of cellular response to the same treatment leads to a whole range of observed values for the recorded cellular features. Consequently, it is difficult to compare and interpret experiments. Moreover, the definition of phenotypic classes at a cell population level remains an open question, although this would ease experiments analyses. In the present work, we tackle these two questions. The input of the method is a series of cell population images for which segmentation and cellular phenotype classification has already been performed. We propose a probabilistic model to represent and later compare cell populations. The model is able to fully exploit the HCS-specific information: "dependence structure of population descriptors" and "within-population variability". The experiments we carried out illustrate how our model accounts for this specific information, as well as the fact that the model benefits from considering them. We underline that these features allow richer HCS data analysis than simpler methods based on single cellular feature values averaged over each well. We validate an HCS data analysis method based on control experiments. It accounts for HCS specificities that were not taken into account by previous methods but have a sound biological meaning. Biological validation of previously unknown outputs of the method constitutes a future line of work.

  1. Task-role-based Access Control Model in Smart Health-care System

    OpenAIRE

    Wang Peng; Jiang Lingyun

    2015-01-01

    As the development of computer science and smart health-care technology, there is a trend for patients to enjoy medical care at home. Taking enormous users in the Smart Health-care System into consideration, access control is an important issue. Traditional access control models, discretionary access control, mandatory access control, and role-based access control, do not properly reflect the characteristics of Smart Health-care System. This paper proposes an advanced access control model for...

  2. Distributed data access in the sequential access model at the D0 experiment at Fermilab

    International Nuclear Information System (INIS)

    Terekhov, Igor; White, Victoria

    2000-01-01

    The authors present the Sequential Access Model (SAM), which is the data handling system for D0, one of two primary High Energy Experiments at Fermilab. During the next several years, the D0 experiment will store a total of about 1 PByte of data, including raw detector data and data processed at various levels. The design of SAM is not specific to the D0 experiment and carries few assumptions about the underlying mass storage level; its ideas are applicable to any sequential data access. By definition, in the sequential access mode a user application needs to process a stream of data, by accessing each data unit exactly once, the order of data units in the stream being irrelevant. The units of data are laid out sequentially in files. The adopted model allows for significant optimizations of system performance, decrease of user file latency and increase of overall throughput. In particular, caching is done with the knowledge of all the files needed in the near future, defined as all the files of the already running or submitted jobs. The bulk of the data is stored in files on tape in the mass storage system (MSS) called Enstore[2] and also developed at Fermilab. (The tape drives are served by an ADIC AML/2 Automated Tape Library). At any given time, SAM has a small fraction of the data cached on disk for processing. In the present paper, the authors discuss how data is delivered onto disk and how it is accessed by user applications. They will concentrate on data retrieval (consumption) from the MSS; when SAM is used for storing of data, the mechanisms are rather symmetrical. All of the data managed by SAM is cataloged in great detail in a relational database (ORACLE). The database also serves as the persistency mechanism for the SAM servers described in this paper. Any client or server in the SAM system which needs to store or retrieve information from the database does so through the interfaces of a CORBA-based database server. The users (physicists) use the

  3. Access to Grafts in a Liver Transplant Center: Does It Rely on the Severity of the Waiting List Population?

    Science.gov (United States)

    Daciuk, N I; Quiñonez, E G; Poupard, M; Vergara Sandoval, R M; Mattera, F J

    2018-03-01

    The number of transplants performed relies, partially, on recipients' variables on the waiting list. The goal of this study was to compare recipients from a high-volume liver center in Argentina with the rest of the country. This study was a retrospective analysis of liver transplant recipients nationally between January 2013 and April 2017. It involved extracting data from the open database CRESI-SINTRA (the Argentinian database of the National Procurement Organization, an equivalent to the United Network for Organ Sharing); expressing results by percentages, medians, and interquartile ranges (IQRs); and comparing the national population with the population transplanted at Hospital El Cruce (HEC). The Mann-Whitney U test was used for analysis. Nationally, 1434 liver transplants were performed. A total of 177 (12.34%) were emergency status; 811 (56.6%) were by the Model for End-Stage Liver Disease (MELD) (n = 759)/PELD (Pediatric End-Stage Liver Disease) (n = 52), with a median graft assignment position of 5 (IQR, 3-10) in 57.2 days (IQR, 11-217). Median MELD access was 29 points (IQR, 24-33). A total of 446 (31.1%) had MELD exceptions; 249 (55.8%) of these were due to Milan hepatocellular carcinoma. At the HEC, 167 liver transplantations were performed; 26 (15.6%) were emergency status and 97 (58.1%) by MELD (none PELD). Their median graft assignment position was 4 (IQR, 4-16) in 19.1 days (IQR, 4-90); median MELD access was 28 points (IQR, 24-31). Forty-five patients (26.9%) had MELD exceptions; 31 (68.9%) were due to hepatocellular carcinoma. Our center has a larger proportion of recipients transplanted by emergency status and MELD, similar MELD access, and less waiting list time, reflecting our wide policy of liver graft acceptance. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Time series sightability modeling of animal populations

    Science.gov (United States)

    ArchMiller, Althea A.; Dorazio, Robert; St. Clair, Katherine; Fieberg, John R.

    2018-01-01

    Logistic regression models—or “sightability models”—fit to detection/non-detection data from marked individuals are often used to adjust for visibility bias in later detection-only surveys, with population abundance estimated using a modified Horvitz-Thompson (mHT) estimator. More recently, a model-based alternative for analyzing combined detection/non-detection and detection-only data was developed. This approach seemed promising, since it resulted in similar estimates as the mHT when applied to data from moose (Alces alces) surveys in Minnesota. More importantly, it provided a framework for developing flexible models for analyzing multiyear detection-only survey data in combination with detection/non-detection data. During initial attempts to extend the model-based approach to multiple years of detection-only data, we found that estimates of detection probabilities and population abundance were sensitive to the amount of detection-only data included in the combined (detection/non-detection and detection-only) analysis. Subsequently, we developed a robust hierarchical modeling approach where sightability model parameters are informed only by the detection/non-detection data, and we used this approach to fit a fixed-effects model (FE model) with year-specific parameters and a temporally-smoothed model (TS model) that shares information across years via random effects and a temporal spline. The abundance estimates from the TS model were more precise, with decreased interannual variability relative to the FE model and mHT abundance estimates, illustrating the potential benefits from model-based approaches that allow information to be shared across years.

  5. A bayesian approach to inferring the genetic population structure of sugarcane accessions from INTA (Argentina

    Directory of Open Access Journals (Sweden)

    Mariana Inés Pocovi

    2015-06-01

    Full Text Available Understanding the population structure and genetic diversity in sugarcane (Saccharum officinarum L. accessions from INTA germplasm bank (Argentina will be of great importance for germplasm collection and breeding improvement as it will identify diverse parental combinations to create segregating progenies with maximum genetic variability for further selection. A Bayesian approach, ordination methods (PCoA, Principal Coordinate Analysis and clustering analysis (UPGMA, Unweighted Pair Group Method with Arithmetic Mean were applied to this purpose. Sixty three INTA sugarcane hybrids were genotyped for 107 Simple Sequence Repeat (SSR and 136 Amplified Fragment Length Polymorphism (AFLP loci. Given the low probability values found with AFLP for individual assignment (4.7%, microsatellites seemed to perform better (54% for STRUCTURE analysis that revealed the germplasm to exist in five optimum groups with partly corresponding to their origin. However clusters shown high degree of admixture, F ST values confirmed the existence of differences among groups. Dissimilarity coefficients ranged from 0.079 to 0.651. PCoA separated sugarcane in groups that did not agree with those identified by STRUCTURE. The clustering including all genotypes neither showed resemblance to populations find by STRUCTURE, but clustering performed considering only individuals displaying a proportional membership > 0.6 in their primary population obtained with STRUCTURE showed close similarities. The Bayesian method indubitably brought more information on cultivar origins than classical PCoA and hierarchical clustering method.

  6. Modified network simulation model with token method of bus access

    Directory of Open Access Journals (Sweden)

    L.V. Stribulevich

    2013-08-01

    Full Text Available Purpose. To study the characteristics of the local network with the marker method of access to the bus its modified simulation model was developed. Methodology. Defining characteristics of the network is carried out on the developed simulation model, which is based on the state diagram-layer network station with the mechanism of processing priorities, both in steady state and in the performance of control procedures: the initiation of a logical ring, the entrance and exit of the station network with a logical ring. Findings. A simulation model, on the basis of which can be obtained the dependencies of the application the maximum waiting time in the queue for different classes of access, and the reaction time usable bandwidth on the data rate, the number of network stations, the generation rate applications, the number of frames transmitted per token holding time, frame length was developed. Originality. The technique of network simulation reflecting its work in the steady condition and during the control procedures, the mechanism of priority ranking and handling was proposed. Practical value. Defining network characteristics in the real-time systems on railway transport based on the developed simulation model.

  7. A semi-automated vascular access system for preclinical models

    International Nuclear Information System (INIS)

    Berry-Pusey, B N; David, J; Taschereau, R; Silverman, R W; Williams, D; Ladno, W; Stout, D; Chatziioannou, A; Chang, Y C; Prince, S W; Chu, K; Tsao, T C

    2013-01-01

    Murine models are used extensively in biological and translational research. For many of these studies it is necessary to access the vasculature for the injection of biologically active agents. Among the possible methods for accessing the mouse vasculature, tail vein injections are a routine but critical step for many experimental protocols. To perform successful tail vein injections, a high skill set and experience is required, leaving most scientists ill-suited to perform this task. This can lead to a high variability between injections, which can impact experimental results. To allow more scientists to perform tail vein injections and to decrease the variability between injections, a vascular access system (VAS) that semi-automatically inserts a needle into the tail vein of a mouse was developed. The VAS uses near infrared light, image processing techniques, computer controlled motors, and a pressure feedback system to insert the needle and to validate its proper placement within the vein. The VAS was tested by injecting a commonly used radiolabeled probe (FDG) into the tail veins of five mice. These mice were then imaged using micro-positron emission tomography to measure the percentage of the injected probe remaining in the tail. These studies showed that, on average, the VAS leaves 3.4% of the injected probe in the tail. With these preliminary results, the VAS system demonstrates the potential for improving the accuracy of tail vein injections in mice. (paper)

  8. Use of models in small mammal population studies

    International Nuclear Information System (INIS)

    Conley, W.; Nichols, J.D.

    1978-01-01

    The role of models as contributors to the understanding of natural populations of small mammals is reviewed. A philosophy of model use and projections for future work are also included. Categories of biological phenomena reviewed include models on population dynamics (demographic variables and population regulation, dispersal, sex-ratios, predation, population cycles), population responses to environmental conditions, genetics of small mammal populations, competitive interactions, ecosystems and small mammal functions, and control and management of small mammal populations

  9. Phase transitions in a lattice population model

    International Nuclear Information System (INIS)

    Windus, Alastair; Jensen, Henrik J

    2007-01-01

    We introduce a model for a population on a lattice with diffusion and birth/death according to 2A→3A and A→Φ for a particle A. We find that the model displays a phase transition from an active to an absorbing state which is continuous in 1 + 1 dimensions and of first-order in higher dimensions in agreement with the mean field equation. For the (1 + 1)-dimensional case, we examine the critical exponents and a scaling function for the survival probability and show that it belongs to the universality class of directed percolation. In higher dimensions, we look at the first-order phase transition by plotting a histogram of the population density and use the presence of phase coexistence to find an accurate value for the critical point in 2 + 1 dimensions

  10. Capturing the Sun: A Roadmap for Navigating Data-Access Challenges and Auto-Populating Solar Home Sales Listings

    Energy Technology Data Exchange (ETDEWEB)

    Stukel, Laura [Elevate Energy, Chicago, IL (United States); Hoen, Ben [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Adomatis, Sandra [Adomatis Appraisal Services, Punta Gorda, FL (United States); Foley, Craig [Sustainable Real Estate Consulting Services, Somerville, MA (United States); Parsons, Laura [Center for Sustainable Energy, San Diego, CA (United States); James, Mark [Vermont Law School, South Royalton, VT (United States). Inst. for Energy and Environment; Mastor, Roxana-Andreea [Vermont Law School, South Royalton, VT (United States). Inst. for Energy and Environment; Wedewer, Lindsey [Colorado Energy Office, Denver, CO (United States)

    2017-04-13

    Capturing the Sun: A Roadmap for Navigating Data-Access Challenges and Auto-Populating Solar Home Sales Listings supports a vision of solar photovoltaic (PV) advocates and real estate advocates evolving together to make information about solar homes more accessible to home buyers and sellers and to simplify the process when these homes are resold. The Roadmap is based on a concept in the real estate industry known as automatic population of fields. Auto-population (also called auto-pop in the industry) is the technology that allows data aggregated by an outside industry to be matched automatically with home sale listings in a multiple listing service (MLS).

  11. Increasing Public Awareness of Direct-to-Consumer Genetic Tests: Health Care Access, Internet Use, and Population Density Correlates

    International Nuclear Information System (INIS)

    Rutten, L. J. F.; Gollust, S. E.; Naveed, S.; Moser, R. P.

    2012-01-01

    Uncertainty around the value of and appropriate regulatory models for direct-to-consumer (DTC) genetic testing underscores the importance of tracking public awareness of these services. We analyzed nationally representative, cross-sectional data from the Health Information National Trends Survey in 2008 (n=7, 674) and 2011 (n=3, 959) to assess population-level changes in awareness of DTC genetic testing in the U.S. and to explore socio demographic, health care, Internet use, and population density correlates. Overall, awareness increased significantly from 29% in 2008 to 37% in 2011. The observed increase in awareness from 2008 to 2011 remained significant (OR=1.39) even when adjusted for socio demographic variables, health care access, Internet use, and population density. Independent of survey year, the odds of awareness of DTC genetic tests were significantly higher for those aged 50-64 (OR=1.64), and 65-74 (O R=1.60); college graduates (OR=2.02 ); those with a regular source of health care (OR=1.27); those with a prior cancer diagnosis (OR=1.24); those who use the Internet (OR=1.27); and those living in urban areas ( OR=1.25). Surveillance of awareness-along with empirical data on use of and response to genetic risk information-can inform public health and policy efforts to maximize benefits and minimize risks of DTC genetic testing.

  12. Increasing Public Awareness of Direct-to-Consumer Genetic Tests: Health Care Access, Internet Use, and Population Density Correlates

    Directory of Open Access Journals (Sweden)

    Lila J. Finney Rutten

    2012-01-01

    Full Text Available Uncertainty around the value of and appropriate regulatory models for direct-to-consumer (DTC genetic testing underscores the importance of tracking public awareness of these services. We analyzed nationally representative, cross-sectional data from the Health Information National Trends Survey in 2008 (n=7,674 and 2011 (n=3,959 to assess population-level changes in awareness of DTC genetic testing in the U.S. and to explore sociodemographic, health care, Internet use, and population density correlates. Overall, awareness increased significantly from 29% in 2008 to 37% in 2011. The observed increase in awareness from 2008 to 2011 remained significant (OR=1.39 even when adjusted for sociodemographic variables, health care access, Internet use, and population density. Independent of survey year, the odds of awareness of DTC genetic tests were significantly higher for those aged 50–64 (OR=1.64, and 65–74 (OR=1.60; college graduates (OR=2.02; those with a regular source of health care (OR=1.27; those with a prior cancer diagnosis (OR=1.24; those who use the Internet (OR=1.27; and those living in urban areas (OR=1.25. Surveillance of awareness—along with empirical data on use of and response to genetic risk information—can inform public health and policy efforts to maximize benefits and minimize risks of DTC genetic testing.

  13. Increasing Public Awareness of Direct-to-Consumer Genetic Tests: Health Care Access, Internet Use, and Population Density Correlates.

    Science.gov (United States)

    Finney Rutten, Lila J; Gollust, Sarah E; Naveed, Sana; Moser, Richard P

    2012-01-01

    Uncertainty around the value of and appropriate regulatory models for direct-to-consumer (DTC) genetic testing underscores the importance of tracking public awareness of these services. We analyzed nationally representative, cross-sectional data from the Health Information National Trends Survey in 2008 (n = 7, 674) and 2011 (n = 3, 959) to assess population-level changes in awareness of DTC genetic testing in the U.S. and to explore sociodemographic, health care, Internet use, and population density correlates. Overall, awareness increased significantly from 29% in 2008 to 37% in 2011. The observed increase in awareness from 2008 to 2011 remained significant (OR = 1.39) even when adjusted for sociodemographic variables, health care access, Internet use, and population density. Independent of survey year, the odds of awareness of DTC genetic tests were significantly higher for those aged 50-64 (OR = 1.64), and 65-74 (OR = 1.60); college graduates (OR = 2.02); those with a regular source of health care (OR = 1.27); those with a prior cancer diagnosis (OR = 1.24); those who use the Internet (OR = 1.27); and those living in urban areas (OR = 1.25). Surveillance of awareness-along with empirical data on use of and response to genetic risk information-can inform public health and policy efforts to maximize benefits and minimize risks of DTC genetic testing.

  14. Population Model with a Dynamic Food Supply

    Science.gov (United States)

    Dickman, Ronald; da Silva Nascimento, Jonas

    2009-09-01

    We propose a simple population model including the food supply as a dynamic variable. In the model, survival of an organism depends on a certain minimum rate of food consumption; a higher rate of consumption is required for reproduction. We investigate the stationary behavior under steady food input, and the transient behavior of growth and decay when food is present initially but is not replenished. Under a periodic food supply, the system exhibits period-doubling bifurcations and chaos in certain ranges of the reproduction rate. Bifurcations and chaos are favored by a slow reproduction rate and a long period of food-supply oscillation.

  15. Access to Orthopaedic Surgical Care in Northern Tanzania: A Modelling Study.

    Science.gov (United States)

    Premkumar, Ajay; Ying, Xiaohan; Mack Hardaker, W; Massawe, Honest H; Mshahaba, David J; Mandari, Faiton; Pallangyo, Anthony; Temu, Rogers; Masenga, Gileard; Spiegel, David A; Sheth, Neil P

    2018-04-25

    The global burden of musculoskeletal disease and resulting disability is enormous and is expected to increase over the next few decades. In the world's poorest regions, the paucity of information defining and quantifying the current state of access to orthopaedic surgical care is a major problem in developing effective solutions. This study estimates the number of individuals in Northern Tanzania without adequate access to orthopaedic surgical services. A chance tree was created to model the probability of access to orthopaedic surgical services in the Northern Tanzanian regions of Arusha, Kilimanjaro, Tanga, Singida, and Manyara, with respect to four dimensions: timeliness, surgical capacity, safety, and affordability. Timeliness was estimated by the proportion of people living within a 4-h driving distance from a hospital with an orthopaedic surgeon, capacity by comparing number of surgeries performed to the number of surgeries indicated, safety by applying WHO Emergency and Essential Surgical Care infrastructure and equipment checklists, and affordability by approximating the proportion of the population protected from catastrophic out-of-pocket healthcare expenditure. We accounted for uncertainty in our model with one-way and probabilistic sensitivity analyses. Data sources included the Tanzanian National Bureau of Statistics and Ministry of Finance, World Bank, World Health Organization, New Zealand Ministry of Health, Google Corporation, NASA population estimator, and 2015 hospital records from Kilimanjaro Christian Medical Center, Machame Hospital, Nkoroanga Hospital, Mt. Meru Hospital, and Arusha Lutheran Medical Center. Under the most conservative assumptions, more than 90% of the Northern Tanzanian population does not have access to orthopaedic surgical services. There is a near absence of access to orthopaedic surgical care in Northern Tanzania. These findings utilize more precise country and region-specific data and are consistent with prior published

  16. Tinamit: Making coupled system dynamics models accessible to stakeholders

    Science.gov (United States)

    Malard, Julien; Inam Baig, Azhar; Rojas Díaz, Marcela; Hassanzadeh, Elmira; Adamowski, Jan; Tuy, Héctor; Melgar-Quiñonez, Hugo

    2017-04-01

    Model coupling is increasingly used as a method of combining the best of two models when representing socio-environmental systems, though barriers to successful model adoption by stakeholders are particularly present with the use of coupled models, due to their high complexity and typically low implementation flexibility. Coupled system dynamics - physically-based modelling is a promising method to improve stakeholder participation in environmental modelling while retaining a high level of complexity for physical process representation, as the system dynamics components are readily understandable and can be built by stakeholders themselves. However, this method is not without limitations in practice, including 1) inflexible and complicated coupling methods, 2) difficult model maintenance after the end of the project, and 3) a wide variety of end-user cultures and languages. We have developed the open-source Python-language software tool Tinamit to overcome some of these limitations to the adoption of stakeholder-based coupled system dynamics - physically-based modelling. The software is unique in 1) its inclusion of both a graphical user interface (GUI) and a library of available commands (API) that allow users with little or no coding abilities to rapidly, effectively, and flexibly couple models, 2) its multilingual support for the GUI, allowing users to couple models in their preferred language (and to add new languages as necessary for their community work), and 3) its modular structure allowing for very easy model coupling and modification without the direct use of code, and to which programming-savvy users can easily add support for new types of physically-based models. We discuss how the use of Tinamit for model coupling can greatly increase the accessibility of coupled models to stakeholders, using an example of a stakeholder-built system dynamics model of soil salinity issues in Pakistan coupled with the physically-based soil salinity and water flow model

  17. Assessing internet access and use in a medically underserved population: implications for providing enhanced health information services.

    Science.gov (United States)

    Zach, Lisl; Dalrymple, Prudence W; Rogers, Michelle L; Williver-Farr, Heather

    2012-03-01

    The relationship between health information seeking, patient engagement and health literacy is not well understood. This is especially true in medically underserved populations, which are often viewed as having limited access to health information. To improve communication between an urban health centre and the community it serves, a team of library and information science researchers undertook an assessment of patients' level and methods of access to and use of the Internet. Data were collected in 53 face-to-face anonymous interviews with patients at the centre. Interviews were tape-recorded for referential accuracy, and data were analysed to identify patterns of access and use. Seventy-two percentage of study participants reported having access to the Internet through either computers or cell phones. Barriers to Internet access were predominantly lack of equipment or training rather than lack of interest. Only 21% of those with Internet access reported using the Internet to look for health information. The findings suggest that lack of access to the Internet in itself is not the primary barrier to seeking health information in this population and that the digital divide exists not at the level of information access but rather at the level of information use. © 2011 The authors. Health Information and Libraries Journal © 2011 Health Libraries Group.

  18. Performance analysis of quantum access network using code division multiple access model

    International Nuclear Information System (INIS)

    Hu Linxi; Yang Can; He Guangqiang

    2017-01-01

    A quantum access network has been implemented by frequency division multiple access and time division multiple access, while code division multiple access is limited for its difficulty to realize the orthogonality of the code. Recently, the chaotic phase shifters were proposed to guarantee the orthogonality by different chaotic signals and spread the spectral content of the quantum states. In this letter, we propose to implement the code division multiple access quantum network by using chaotic phase shifters and synchronization. Due to the orthogonality of the different chaotic phase shifter, every pair of users can faithfully transmit quantum information through a common channel and have little crosstalk between different users. Meanwhile, the broadband spectra of chaotic signals efficiently help the quantum states to defend against channel loss and noise. (paper)

  19. Connectivity and conditional models of access and abundance of species in stream networks.

    Science.gov (United States)

    Chelgren, Nathan D; Dunham, Jason B

    2015-07-01

    Barriers to passage of aquatic organisms at stream road crossings are a major cause of habitat fragmentation in stream networks. Accordingly, large investments have been made to restore passage at these crossings, but often without estimation of population-level benefits. Here, we describe a broad-scale approach to quantifying the effectiveness of passage restoration in terms interpretable at population levels, namely numbers of fish and length of stream gained through restoration, by sampling abundance in a study design that accounts for variable biogeographic species pools, variable stream and barrier configurations, and variable probabilities of capture and detectability for multiple species. We modified an existing zero-inflated negative-binomial model to estimate the probability of site access, abundance conditional on access, and capture probability of individual fish. Therein, we modeled probability of access as a function of gradient, stream road-crossing type, and downstream access by fish simultaneously with a predictive model for abundance at sites accessible to fish. Results indicated that replacement of barriers with new crossing designs intended to allow for greater movement was associated with dramatically higher probability of access for all fishes, including migratory Pacific salmon, trout, sculpin, and lamprey. Conversely, existing non-replaced crossings negatively impacted fish distributions. Assuming no downstream constraints on access, we estimated the potential length of stream restored by the program ranged between 7.33 (lamprey) and 15.28 km (small coastal cutthroat and rainbow trout). These contributions represented a fraction of the total length available upstream (187 km) of replaced crossings. When limited ranges of species were considered, the estimated contributions of culvert replacement were reduced (1.65-km range, for longnose dace to 12.31 km for small coastal cutthroat and rainbow trout). Numbers of fish contributed ranged from

  20. Notified Access: Extending Remote Memory Access Programming Models for Producer-Consumer Synchronization

    KAUST Repository

    Belli, Roberto; Hoefler, Torsten

    2015-01-01

    Remote Memory Access (RMA) programming enables direct access to low-level hardware features to achieve high performance for distributed-memory programs. However, the design of RMA programming schemes focuses on the memory access and less on the synchronization. For example, in contemporary RMA programming systems, the widely used producer-consumer pattern can only be implemented inefficiently, incurring in an overhead of an additional round-trip message. We propose Notified Access, a scheme where the target process of an access can receive a completion notification. This scheme enables direct and efficient synchronization with a minimum number of messages. We implement our scheme in an open source MPI-3 RMA library and demonstrate lower overheads (two cache misses) than other point-to-point synchronization mechanisms for each notification. We also evaluate our implementation on three real-world benchmarks, a stencil computation, a tree computation, and a Colicky factorization implemented with tasks. Our scheme always performs better than traditional message passing and other existing RMA synchronization schemes, providing up to 50% speedup on small messages. Our analysis shows that Notified Access is a valuable primitive for any RMA system. Furthermore, we provide guidance for the design of low-level network interfaces to support Notified Access efficiently.

  1. Notified Access: Extending Remote Memory Access Programming Models for Producer-Consumer Synchronization

    KAUST Repository

    Belli, Roberto

    2015-05-01

    Remote Memory Access (RMA) programming enables direct access to low-level hardware features to achieve high performance for distributed-memory programs. However, the design of RMA programming schemes focuses on the memory access and less on the synchronization. For example, in contemporary RMA programming systems, the widely used producer-consumer pattern can only be implemented inefficiently, incurring in an overhead of an additional round-trip message. We propose Notified Access, a scheme where the target process of an access can receive a completion notification. This scheme enables direct and efficient synchronization with a minimum number of messages. We implement our scheme in an open source MPI-3 RMA library and demonstrate lower overheads (two cache misses) than other point-to-point synchronization mechanisms for each notification. We also evaluate our implementation on three real-world benchmarks, a stencil computation, a tree computation, and a Colicky factorization implemented with tasks. Our scheme always performs better than traditional message passing and other existing RMA synchronization schemes, providing up to 50% speedup on small messages. Our analysis shows that Notified Access is a valuable primitive for any RMA system. Furthermore, we provide guidance for the design of low-level network interfaces to support Notified Access efficiently.

  2. Equity in access to health care in a rural population in Malaysia: A cross-sectional study.

    Science.gov (United States)

    Lim, Ka Keat; Sivasampu, Sheamini; Mahmud, Fatihah

    2017-04-01

    To examine the extent of equity in access to health care, their determinants and reasons of unmet need of a rural population in Malaysia. Exploratory cross-sectional survey administered by trained interviewers among participants of a health screening program. A rural plantation estate in the West Coast of Peninsular Malaysia. One hundred and thirty out of 142 adults above 18 years old who attended the program. Percentages of respondents reporting realised access and unmet need to health care, determinants of both access indicators and reasons for unmet need. Realised access associated with need but not predisposing or enabling factors and unmet need not associated with any variables were considered equitable. A total of 88 (67.7%) respondents had visited a doctor (realised access) in the past 6 months and 24.8% (n = 31) experienced unmet need in the past 12 months. Using logistic regression, realised access was associated with presence of chronic disease (OR 6.97, P  RM 2000 per month) (OR 51.27, P population, the latter associated with education level, subjective health status and income. Despite not being generalisable, the findings highlight the need for a national level study on equity in access before the country reforms its health system. © 2016 National Rural Health Alliance Inc.

  3. Population matrix models and palm resource management

    Directory of Open Access Journals (Sweden)

    1992-01-01

    Full Text Available MATRICES DE POPULATIONS ET MISE EN VALEUR DES PALMIERS. Au cours des 20 dernières années, les structures de population de nombreuses espèces de palmiers ont été décrites et discutées. La croissance et la stabilité des populations ont été analysées à l’aide de matrices. Dans cet article, nous reprenons un modèle et en discutons les aspects méthodologiques en vue d’une estimation des paramètres de l’histoire de la vie des palmiers. Les généralisations résultant de précédentes études sont présentées et les conséquences pour la mise en valeur des palmiers, concernant en particulier la confection de toitures, les fruits, la récolte des stipes, sont discutées. MATRICES DE POBLACIONES Y MANEJO DE PALMERAS. En los últimos 20 años, las estructuras de población de numerosas especies de palmeras han sido descritas y discutidas. El crecimiento y la estabilidad de las poblaciones han sido analizadas, utilizando matrices. En el presente artículo, presentamos un modelo y discutimos los aspectos metodológicos específicos para hacer una estimación de los parámetros de la historia de la vida de las palmeras. Son presentadas las generalizaciones diseñadas por estudios previos, y discutidas las implicancias en el manejo de las palmeras, en cuanto a techado, frutas, cosecha de los estípites. Population structures of numerous palm species have been described and discussed in the last 20 years. Population growth and stability have been analyzed with matrix models. In this paper we review matrix models and discuss methodological issues specific to estimating palm life history parameters. Generalizations drawn from previous studies are presented and implications for palm resource management, specifically for thatch, fruit, and stem harvest, are discussed.

  4. A discrete choice approach to modeling food store access

    OpenAIRE

    Amy Hillier; Tony Smith; Carolyn C Cannuscio; Allison Karpyn; Karen Glanz

    2015-01-01

    Assessments of access to healthful food frequently use GIS to measure the distance and concentration of food outlets relative to where residents live. These descriptive approaches do not account for food shopping behavior, which may vary based on the attributes of food shoppers and their activity space—places where they live, work, access resources, and socialize. Building on transportation research about accessibility, we reframe the issue of food access and equity from one about ‘what is ne...

  5. Access and Attitudes to HPV Vaccination amongst Hard-To-Reach Populations in Kenya.

    Directory of Open Access Journals (Sweden)

    Deborah Watson-Jones

    Full Text Available Sub-Saharan Africa bears the greatest burden of cervical cancer. Human papillomavirus (HPV vaccination programmes to prevent the disease will need to reach vulnerable girls who may not be able access health and screening services in the future. We conducted formative research on facilitators and barriers to HPV vaccination and potential acceptability of a future HPV vaccination programme amongst girls living in hard-to-reach populations in Kenya.Stakeholder interviews with Ministry of Health staff explored barriers to and support for the uptake of HPV vaccination. A situation assessment was conducted to assess community services in Maasai nomadic pastoralist communities in Kajiado County and in Korogocho informal settlement in Nairobi city, followed by focus group discussions (n=14 and semi-structured interviews (n=28 with health workers, parents, youth, and community and religious leaders. These covered marriage, knowledge of cervical cancer and HPV, factors that might inhibit or support HPV vaccine uptake and intention to accept HPV vaccine if a programme was in place.Reported challenges to an HPV vaccination programme included school absenteeism and drop-out, early age of sex and marriage, lack of parental support, population mobility and distance from services. Despite little prior knowledge of cervical cancer and HPV, communities were interested in receiving HPV vaccination. Adequate social mobilisation and school-based vaccination, supplemented by out-reach activities, were considered important facilitating factors to achieve high coverage. There was some support for a campaign approach to vaccine delivery.Given the high level of support for a vaccine against cervical cancer and the experience of reaching pastoralist and slum-dwellers for other immunizations, implementing an HPV vaccine programme should be feasible in such hard-to-reach communities. This may require additional delivery strategies in addition to the standard school

  6. Improving Maternal Healthcare Access and Neonatal Survival through a Birthing Home Model in Rural Haiti

    Directory of Open Access Journals (Sweden)

    Elizabeth Wickstrom

    2007-10-01

    Full Text Available High neonatal mortality in Haiti is sustained by limited access to essential maternity services, particularly for Haiti’s rural population. We investigated the feasibility of a rural birthing home model to provide basic prenatal, delivery, and neonatal services for women with uncomplicated pregnancies while simultaneously providing triage and transport of women with pregnancy related complications. The model included consideration of the local context, including women’s perceptions of barriers to healthcare access and available resources to implement change. Evaluation methods included the performance of a baseline community census and collection of pregnancy histories from 791 women living in a defined area of rural Haiti. These retrospective data were compared with pregnancy outcome for 668 women subsequently receiving services at the birthing home. Of 764 reported most recent pregnancies in the baseline survey, 663(87% occurred at home with no assistance from skilled health staff. Of 668 women followed after opening of the birthing home, 514 (77% subsequently gave birth at the birthing home, 94 (14% were referred to a regional hospital for delivery, and only 60 (9% delivered at home or on the way to the birthing home. Other measures of clinical volume and patient satisfaction also indicated positive changes in health care seeking. After introduction of the birthing home, fewer neonates died than predicted by historical information or national statistics. The present experience points out the feasibility of a rural birthing home model to increase access to essential maternity services.

  7. Access and completion of a Web-based treatment in a population-based sample of tornado-affected adolescents.

    Science.gov (United States)

    Price, Matthew; Yuen, Erica K; Davidson, Tatiana M; Hubel, Grace; Ruggiero, Kenneth J

    2015-08-01

    Although Web-based treatments have significant potential to assess and treat difficult-to-reach populations, such as trauma-exposed adolescents, the extent that such treatments are accessed and used is unclear. The present study evaluated the proportion of adolescents who accessed and completed a Web-based treatment for postdisaster mental health symptoms. Correlates of access and completion were examined. A sample of 2,000 adolescents living in tornado-affected communities was assessed via structured telephone interview and invited to a Web-based treatment. The modular treatment addressed symptoms of posttraumatic stress disorder, depression, and alcohol and tobacco use. Participants were randomized to experimental or control conditions after accessing the site. Overall access for the intervention was 35.8%. Module completion for those who accessed ranged from 52.8% to 85.6%. Adolescents with parents who used the Internet to obtain health-related information were more likely to access the treatment. Adolescent males were less likely to access the treatment. Future work is needed to identify strategies to further increase the reach of Web-based treatments to provide clinical services in a postdisaster context. (c) 2015 APA, all rights reserved).

  8. Access to medication in the Public Health System and equity: populational health surveys in São Paulo, Brazil.

    Science.gov (United States)

    Monteiro, Camila Nascimento; Gianini, Reinaldo José; Barros, Marilisa Berti de Azevedo; Cesar, Chester Luiz Galvão; Goldbaum, Moisés

    2016-03-01

    Since 2003, the access to medication has been increasing in Brazil and particularly in São Paulo. The present study aimed to analyze the access to medication obtained in the public sector and the socioeconomic differences in this access in 2003 and 2008. Also, we explored the difference in access to medication from 2003 to 2008. Data were obtained from two cross-sectional population-based household surveys from São Paulo, Brazil (ISA-Capital 2003 and ISA-Capital 2008). Concentration curve and concentration index were calculated to analyze the associations between socioeconomic factors and access to medication in the public sector. Additionally, the differences between 2003 and 2008 regarding socioeconomic characteristics and access to medication were studied. Access to medication was 89.55% in 2003 and 92.99% in 2008, and the proportion of access to medication did not change in the period. Access in the public sector increased from 26.40% in 2003 to 48.55% in 2008 and there was a decrease in the concentration index between 2003 and 2008 in access to medication in the public sector. The findings indicate an expansion of Brazilian Unified Health System (Sistema Único de Saúde ) users, with the inclusion of people of higher socioeconomic position in the public sector. As the SUS gives more support to people of lower socioeconomic position in terms of medication provision, the SUS tends to equity. Nevertheless, universal coverage for medication and equity in access to medication in the public sector are still challenges for the Brazilian public health system.

  9. Monte Carlo simulation models of breeding-population advancement.

    Science.gov (United States)

    J.N. King; G.R. Johnson

    1993-01-01

    Five generations of population improvement were modeled using Monte Carlo simulations. The model was designed to address questions that are important to the development of an advanced generation breeding population. Specifically we addressed the effects on both gain and effective population size of different mating schemes when creating a recombinant population for...

  10. Population genetics of Setaria viridis, a new model system.

    Science.gov (United States)

    Huang, Pu; Feldman, Maximilian; Schroder, Stephan; Bahri, Bochra A; Diao, Xianmin; Zhi, Hui; Estep, Matt; Baxter, Ivan; Devos, Katrien M; Kellogg, Elizabeth A

    2014-10-01

    An extensive survey of the standing genetic variation in natural populations is among the priority steps in developing a species into a model system. In recent years, green foxtail (Setaria viridis), along with its domesticated form foxtail millet (S. italica), has rapidly become a promising new model system for C4 grasses and bioenergy crops, due to its rapid life cycle, large amount of seed production and small diploid genome, among other characters. However, remarkably little is known about the genetic diversity in natural populations of this species. In this study, we survey the genetic diversity of a worldwide sample of more than 200 S. viridis accessions, using the genotyping-by-sequencing technique. Two distinct genetic groups in S. viridis and a third group resembling S. italica were identified, with considerable admixture among the three groups. We find the genetic variation of North American S. viridis correlates with both geography and climate and is representative of the total genetic diversity in this species. This pattern may reflect several introduction/dispersal events of S. viridis into North America. We also modelled demographic history and show signal of recent population decline in one subgroup. Finally, we show linkage disequilibrium decay is rapid (<45 kb) in our total sample and slow in genetic subgroups. These results together provide an in-depth understanding of the pattern of genetic diversity of this new model species on a broad geographic scale. They also provide key guidelines for on-going and future work including germplasm preservation, local adaptation, crossing designs and genomewide association studies. © 2014 John Wiley & Sons Ltd.

  11. Trading on extinction: An open-access deterrence model for the South African abalone fishery

    Directory of Open Access Journals (Sweden)

    Douglas J. Crookes

    2016-03-01

    Full Text Available South African rhinoceros (e.g.Diceros bicornis and abalone (Haliotis midae have in common that they both are harvested under open-access conditions, are high-value commodities and are traded illegally. The difference is that a legal market for abalone already exists. An open-access deterrence model was developed for South African abalone, using Table Mountain National Park as a case study. It was found that illegal poaching spiked following the closure of the recreational fishery. The resource custodian's objective is to maximise returns from confiscations. This study showed that a legal trade results in a trading on extinction resource trap, with a race for profits, an increase in the probability of detection after a poaching event and the depletion of populations. In contrast with HS Gordon's seminal article (J Polit Econ 1954;62:124-142, profit maximisation does not automatically improve the sustainability of the resource. Under certain conditions (e.g. a legal trade with costly enforcement, profit maximisation may actually deplete abalone populations. The article also has implications for rhino populations, as a legal trade is currently proposed.

  12. The Open Access Association? EAHIL's new model for sustainability.

    Science.gov (United States)

    McSean, Tony; Jakobsson, Arne

    2009-12-01

    To discover a governance structure and a business model for the European Association for Health Information and Libraries (EAHIL) which will be economically sustainable in the medium term, arresting a long-term gradual decline in membership numbers and implementing new revenue streams to sustain association activity. Reviewed survival strategies of other professional associations, investigated potential of emerging interactive web technologies, investigated alternative revenue streams based around the 'franchise' of the annual EAHIL conferences and workshops. A fully worked-through and costed alternative structure was produced, based on abolition of the subscription, web-based procedures and functions, increased income from advertising and sponsorship and a large measure of member participation and engagement. Statutes and Rules of Procedure were rewritten to reflect the changes. This plan was put through the Association's approval cycle and implemented in 2005. The new financial model has proved itself sustainable on the basis of the first 2 years' operations. The long-term gradual decline in membership was reversed, with membership numbers trebling across the EAHIL region. The software worked with minimal problems, including the online electoral process. With no identified precedent from other professional associations, the changes represented a considerable risk, which was justifiable because long-term projections made it clear that continuing the traditional model was not viable. The result is a larger, healthier association with a stronger link to its membership. Long-term risks include the high level of member commitment and expertise. There are also important questions about scalability-diseconomies of scale probably limit the applicability of the overall open access model to larger associations.

  13. Probabilistic models of population evolution scaling limits, genealogies and interactions

    CERN Document Server

    Pardoux, Étienne

    2016-01-01

    This expository book presents the mathematical description of evolutionary models of populations subject to interactions (e.g. competition) within the population. The author includes both models of finite populations, and limiting models as the size of the population tends to infinity. The size of the population is described as a random function of time and of the initial population (the ancestors at time 0). The genealogical tree of such a population is given. Most models imply that the population is bound to go extinct in finite time. It is explained when the interaction is strong enough so that the extinction time remains finite, when the ancestral population at time 0 goes to infinity. The material could be used for teaching stochastic processes, together with their applications. Étienne Pardoux is Professor at Aix-Marseille University, working in the field of Stochastic Analysis, stochastic partial differential equations, and probabilistic models in evolutionary biology and population genetics. He obtai...

  14. Dynamic analysis of a parasite population model

    Science.gov (United States)

    Sibona, G. J.; Condat, C. A.

    2002-03-01

    We study the dynamics of a model that describes the competitive interaction between an invading species (a parasite) and its antibodies in an living being. This model was recently used to examine the dynamical competition between Tripanosoma cruzi and its antibodies during the acute phase of Chagas' disease. Depending on the antibody properties, the model yields three types of outcomes, corresponding, respectively, to healing, chronic disease, and host death. Here, we study the dynamics of the parasite-antibody interaction with the help of simulations, obtaining phase trajectories and phase diagrams for the system. We show that, under certain conditions, the size of the parasite inoculation can be crucial for the infection outcome and that a retardation in the stimulated production of an antibody species may result in the parasite gaining a definitive advantage. We also find a criterion for the relative sizes of the parameters that are required if parasite-generated decoys are indeed to help the invasion. Decoys may also induce a qualitatively different outcome: a limit cycle for the antibody-parasite population phase trajectories.

  15. Population Density Modeling for Diverse Land Use Classes: Creating a National Dasymetric Worker Population Model

    Science.gov (United States)

    Trombley, N.; Weber, E.; Moehl, J.

    2017-12-01

    Many studies invoke dasymetric mapping to make more accurate depictions of population distribution by spatially restricting populations to inhabited/inhabitable portions of observational units (e.g., census blocks) and/or by varying population density among different land classes. LandScan USA uses this approach by restricting particular population components (such as residents or workers) to building area detected from remotely sensed imagery, but also goes a step further by classifying each cell of building area in accordance with ancillary land use information from national parcel data (CoreLogic, Inc.'s ParcelPoint database). Modeling population density according to land use is critical. For instance, office buildings would have a higher density of workers than warehouses even though the latter would likely have more cells of detection. This paper presents a modeling approach by which different land uses are assigned different densities to more accurately distribute populations within them. For parts of the country where the parcel data is insufficient, an alternate methodology is developed that uses National Land Cover Database (NLCD) data to define the land use type of building detection. Furthermore, LiDAR data is incorporated for many of the largest cities across the US, allowing the independent variables to be updated from two-dimensional building detection area to total building floor space. In the end, four different regression models are created to explain the effect of different land uses on worker distribution: A two-dimensional model using land use types from the parcel data A three-dimensional model using land use types from the parcel data A two-dimensional model using land use types from the NLCD data, and A three-dimensional model using land use types from the NLCD data. By and large, the resultant coefficients followed intuition, but importantly allow the relationships between different land uses to be quantified. For instance, in the model

  16. An Access Control Model for the Uniframe Framework

    National Research Council Canada - National Science Library

    Crespi, Alexander M

    2005-01-01

    ... security characteristics from the properties of individual components would aid in the creation of more secure systems In this thesis, a framework for characterizing the access control properties...

  17. Toward Accessing Spatial Structure from Building Information Models

    Science.gov (United States)

    Schultz, C.; Bhatt, M.

    2011-08-01

    Data about building designs and layouts is becoming increasingly more readily available. In the near future, service personal (such as maintenance staff or emergency rescue workers) arriving at a building site will have immediate real-time access to enormous amounts of data relating to structural properties, utilities, materials, temperature, and so on. The critical problem for users is the taxing and error prone task of interpreting such a large body of facts in order to extract salient information. This is necessary for comprehending a situation and deciding on a plan of action, and is a particularly serious issue in time-critical and safety-critical activities such as firefighting. Current unifying building models such as the Industry Foundation Classes (IFC), while being comprehensive, do not directly provide data structures that focus on spatial reasoning and spatial modalities that are required for high-level analytical tasks. The aim of the research presented in this paper is to provide computational tools for higher level querying and reasoning that shift the cognitive burden of dealing with enormous amounts of data away from the user. The user can then spend more energy and time in planning and decision making in order to accomplish the tasks at hand. We present an overview of our framework that provides users with an enhanced model of "built-up space". In order to test our approach using realistic design data (in terms of both scale and the nature of the building models) we describe how our system interfaces with IFC, and we conduct timing experiments to determine the practicality of our approach. We discuss general computational approaches for deriving higher-level spatial modalities by focusing on the example of route graphs. Finally, we present a firefighting scenario with alternative route graphs to motivate the application of our framework.

  18. An Agent-Based Model for Addressing the Impact of a Disaster on Access to Primary Care Services.

    Science.gov (United States)

    Guclu, Hasan; Kumar, Supriya; Galloway, David; Krauland, Mary; Sood, Rishi; Bocour, Angelica; Hershey, Tina Batra; van Nostrand, Elizabeth; Potter, Margaret

    2016-06-01

    Hurricane Sandy in the Rockaways, Queens, forced residents to evacuate and primary care providers to close or curtail operations. A large deficit in primary care access was apparent in the immediate aftermath of the storm. Our objective was to build a computational model to aid responders in planning to situate primary care services in a disaster-affected area. Using an agent-based modeling platform, HAZEL, we simulated the Rockaways population, its evacuation behavior, and primary care providers' availability in the aftermath of Hurricane Sandy. Data sources for this model included post-storm and community health surveys from New York City, a survey of the Rockaways primary care providers, and research literature. The model then tested geospatially specific interventions to address storm-related access deficits. The model revealed that areas of high primary care access deficit were concentrated in the eastern part of the Rockaways. Placing mobile health clinics in the most populous census tracts reduced the access deficit significantly, whereas increasing providers' capacity by 50% reduced the deficit to a lesser degree. An agent-based model may be a useful tool to have in place so that policy makers can conduct scenario-based analyses to plan interventions optimally in the event of a disaster. (Disaster Med Public Health Preparedness. 2016;10:386-393).

  19. Geographical accessibility and spatial coverage modeling of the primary health care network in the Western Province of Rwanda

    Directory of Open Access Journals (Sweden)

    Huerta Munoz Ulises

    2012-09-01

    Full Text Available Abstract Background Primary health care is essential in improving and maintaining the health of populations. It has the potential to accelerate achievement of the Millennium Development Goals and fulfill the “Health for All” doctrine of the Alma-Ata Declaration. Understanding the performance of the health system from a geographic perspective is important for improved health planning and evidence-based policy development. The aims of this study were to measure geographical accessibility, model spatial coverage of the existing primary health facility network, estimate the number of primary health facilities working under capacity and the population underserved in the Western Province of Rwanda. Methods This study uses health facility, population and ancillary data for the Western Province of Rwanda. Three different travel scenarios utilized by the population to attend the nearest primary health facility were defined with a maximum travelling time of 60 minutes: Scenario 1 – walking; Scenario 2 – walking and cycling; and Scenario 3 – walking and public transportation. Considering these scenarios, a raster surface of travel time between primary health facilities and population was developed. To model spatial coverage and estimate the number of primary health facilities working under capacity, the catchment area of each facility was calculated by taking into account population coverage capacity, the population distribution, the terrain topography and the travelling modes through the different land categories. Results Scenario 2 (walking and cycling has the highest degree of geographical accessibility followed by Scenario 3 (walking and public transportation. The lowest level of accessibility can be observed in Scenario 1 (walking. The total population covered differs depending on the type of travel scenario. The existing primary health facility network covers only 26.6% of the population in Scenario 1. In Scenario 2, the use of a bicycle

  20. Task-role-based Access Control Model in Smart Health-care System

    Directory of Open Access Journals (Sweden)

    Wang Peng

    2015-01-01

    Full Text Available As the development of computer science and smart health-care technology, there is a trend for patients to enjoy medical care at home. Taking enormous users in the Smart Health-care System into consideration, access control is an important issue. Traditional access control models, discretionary access control, mandatory access control, and role-based access control, do not properly reflect the characteristics of Smart Health-care System. This paper proposes an advanced access control model for the medical health-care environment, task-role-based access control model, which overcomes the disadvantages of traditional access control models. The task-role-based access control (T-RBAC model introduces a task concept, dividing tasks into four categories. It also supports supervision role hierarchy. T-RBAC is a proper access control model for Smart Health-care System, and it improves the management of access rights. This paper also proposes an implementation of T-RBAC, a binary two-key-lock pair access control scheme using prime factorization.

  1. Modeling livestock population structure: a geospatial database for Ontario swine farms.

    Science.gov (United States)

    Khan, Salah Uddin; O'Sullivan, Terri L; Poljak, Zvonimir; Alsop, Janet; Greer, Amy L

    2018-01-30

    Infectious diseases in farmed animals have economic, social, and health consequences. Foreign animal diseases (FAD) of swine are of significant concern. Mathematical and simulation models are often used to simulate FAD outbreaks and best practices for control. However, simulation outcomes are sensitive to the population structure used. Within Canada, access to individual swine farm population data with which to parameterize models is a challenge because of privacy concerns. Our objective was to develop a methodology to model the farmed swine population in Ontario, Canada that could represent the existing population structure and improve the efficacy of simulation models. We developed a swine population model based on the factors such as facilities supporting farm infrastructure, land availability, zoning and local regulations, and natural geographic barriers that could affect swine farming in Ontario. Assigned farm locations were equal to the swine farm density described in the 2011 Canadian Census of Agriculture. Farms were then randomly assigned to farm types proportional to the existing swine herd types. We compared the swine population models with a known database of swine farm locations in Ontario and found that the modeled population was representative of farm locations with a high accuracy (AUC: 0.91, Standard deviation: 0.02) suggesting that our algorithm generated a reasonable approximation of farm locations in Ontario. In the absence of a readily accessible dataset providing details of the relative locations of swine farms in Ontario, development of a model livestock population that captures key characteristics of the true population structure while protecting privacy concerns is an important methodological advancement. This methodology will be useful for individuals interested in modeling the spread of pathogens between farms across a landscape and using these models to evaluate disease control strategies.

  2. Lexical access in sign language: a computational model.

    Science.gov (United States)

    Caselli, Naomi K; Cohen-Goldberg, Ariel M

    2014-01-01

    PSYCHOLINGUISTIC THEORIES HAVE PREDOMINANTLY BEEN BUILT UPON DATA FROM SPOKEN LANGUAGE, WHICH LEAVES OPEN THE QUESTION: How many of the conclusions truly reflect language-general principles as opposed to modality-specific ones? We take a step toward answering this question in the domain of lexical access in recognition by asking whether a single cognitive architecture might explain diverse behavioral patterns in signed and spoken language. Chen and Mirman (2012) presented a computational model of word processing that unified opposite effects of neighborhood density in speech production, perception, and written word recognition. Neighborhood density effects in sign language also vary depending on whether the neighbors share the same handshape or location. We present a spreading activation architecture that borrows the principles proposed by Chen and Mirman (2012), and show that if this architecture is elaborated to incorporate relatively minor facts about either (1) the time course of sign perception or (2) the frequency of sub-lexical units in sign languages, it produces data that match the experimental findings from sign languages. This work serves as a proof of concept that a single cognitive architecture could underlie both sign and word recognition.

  3. Lexical access in sign language: A computational model

    Directory of Open Access Journals (Sweden)

    Naomi Kenney Caselli

    2014-05-01

    Full Text Available Psycholinguistic theories have predominantly been built upon data from spoken language, which leaves open the question: How many of the conclusions truly reflect language-general principles as opposed to modality-specific ones? We take a step toward answering this question in the domain of lexical access in recognition by asking whether a single cognitive architecture might explain diverse behavioral patterns in signed and spoken language. Chen and Mirman (2012 presented a computational model of word processing that unified opposite effects of neighborhood density in speech production, perception, and written word recognition. Neighborhood density effects in sign language also vary depending on whether the neighbors share the same handshape or location. We present a spreading activation architecture that borrows the principles proposed by Chen and Mirman (2012, and show that if this architecture is elaborated to incorporate relatively minor facts about either 1 the time course of sign perception or 2 the frequency of sub-lexical units in sign languages, it produces data that match the experimental findings from sign languages. This work serves as a proof of concept that a single cognitive architecture could underlie both sign and word recognition.

  4. Influence of socio-economic status on access to different components of SCI management across Indian population.

    Science.gov (United States)

    Chhabra, H S; Bhalla, A M

    2015-11-01

    To assess the influence of financial constraints on access to different components of spinal cord injury (SCI) management in various socio-economic strata of the Indian population. Indian Spinal Injuries Centre (ISIC). One hundred fifty SCI individuals who came for follow-up at ISIC between March 2009 and March 2013 with at least 1 year of community exposure after discharge were included in the study. Socio-economic classification was carried out according to the Kuppuswamy scale, a standard scale for the Indian population. A self-designed questionnaire was administered. No sample was available from the lower group. There was a statistically significant difference (PSCI management. Aided upper lower group was dependent on welfare schemes for in-hospital treatment but could not access other components of management once discharged. Unaided upper lower group either faced severe difficulty or could not access management. Majority of lower middle group faced severe difficulty. Upper middle group was equally divided into facing severe, moderate or no difficulty. Most patients in the upper group faced no difficulty, whereas some faced moderate and a small number of severe difficulty. Financial constraints affected all components of SCI management in all except the upper group. The results of the survey suggest that a very large percentage of the Indian population would find it difficult to access comprehensive SCI management and advocate extension of essential medical coverage to unaided upper lower, lower middle and upper middle groups.

  5. Switch Based Opportunistic Spectrum Access for General Primary User Traffic Model

    KAUST Repository

    Gaaloul, Fakhreddine

    2012-06-18

    This letter studies cognitive radio transceiver that can opportunistically use the available channels of primary user (PU). Specifically, we investigate and compare two different opportunistic channel access schemes. The first scheme applies when the secondary user (SU) has access to only one channel. The second scheme, based on channel switching mechanism, applies when the SU has access to multiple channels but can at a given time monitor and access only one channel. For these access schemes, we derive the exact analytical results for the novel performance metrics of average access time and average waiting time under general PU traffic models.

  6. Switch Based Opportunistic Spectrum Access for General Primary User Traffic Model

    KAUST Repository

    Gaaloul, Fakhreddine; Alouini, Mohamed-Slim; Radaydeh, Redha M.; Yang, Hong-Chuan

    2012-01-01

    This letter studies cognitive radio transceiver that can opportunistically use the available channels of primary user (PU). Specifically, we investigate and compare two different opportunistic channel access schemes. The first scheme applies when the secondary user (SU) has access to only one channel. The second scheme, based on channel switching mechanism, applies when the SU has access to multiple channels but can at a given time monitor and access only one channel. For these access schemes, we derive the exact analytical results for the novel performance metrics of average access time and average waiting time under general PU traffic models.

  7. Modeling Social Capital as Dynamic Networks to Promote Access to Oral Healthcare.

    Science.gov (United States)

    Wang, Hua; Northridge, Mary E; Kunzel, Carol; Zhang, Qiuyi; Kum, Susan S; Gilbert, Jessica L; Jin, Zhu; Metcalf, Sara S

    2016-01-01

    Social capital, as comprised of human connections in social networks and their associated benefits, is closely related to the health of individuals, communities, and societies at large. For disadvantaged population groups such as older adults and racial/ethnic minorities, social capital may play a particularly critical role in mitigating the negative effects and reinforcing the positive effects on health. In this project, we model social capital as both cause and effect by simulating dynamic networks. Informed in part by a community-based health promotion program, an agent-based model is contextualized in a GIS environment to explore the complexity of social disparities in oral and general health as experienced at the individual, interpersonal, and community scales. This study provides the foundation for future work investigating how health and healthcare accessibility may be influenced by social networks.

  8. Access to HIV community services by vulnerable populations: evidence from an enhanced HIV/AIDS surveillance system.

    Science.gov (United States)

    Madden, H C E; Phillips-Howard, P A; Hargreaves, S C; Downing, J; Bellis, M A; Vivancos, R; Morley, C; Syed, Q; Cook, P A

    2011-05-01

    HIV disproportionately affects vulnerable populations such as black and minority ethnic groups, men who have sex with men (MSM) and migrants, in many countries including those in the UK. Community organisations in the UK are charitable non-governmental organisations with a proportion of the workforce who volunteer, and provide invaluable additional support for people living with HIV (PLWHIV). Information on their contribution to HIV care in vulnerable groups is relatively sparse. Data generated from an enhanced HIV surveillance system in North West England, UK, was utilised for this study. We aimed to determine the characteristics of individuals who chose to access community services in addition to clinical services (1375 out of 4195 records of PLWHIV in clinical services). Demographic information, risk factors including residency status, uniquely gathered in this region, and deprivation scores were examined. Multivariate logistic regression modelling was conducted to predict the relative effect of patient characteristics on attendance at community services. Attendance at community services was highest in those living in the most, compared with least, deprived areas (p<0.001), and was most evident in MSM and heterosexuals. Compared to white UK nationals attendance was significantly higher in non-UK nationals of uncertain residency status (Adjusted odds ratio [AOR] = 21.91, 95% confidence interval [CI] 10.48-45.83; p<0.001), refugees (AOR = 5.75, 95% CI 3.3-10.03; p<0.001), migrant workers (AOR = 5.48, 95% CI 2.22-13.51; p<0.001) and temporary visitors (AOR = 3.44, 95% CI 1.68-7.05; p<0.001). Community services, initially established predominantly to support MSM, have responded to the changing demography of HIV and reach the most vulnerable members of society. Consequent to their support of migrant populations, community services are vital for the management of HIV in black and minority groups. Paradoxically, this coincides with increasing funding pressures on these

  9. An Efficient Role and Object Based Access Control Model Implemented in a PDM System

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiaowen; TAN Jian; HUANG Xiangguo

    2006-01-01

    An effective and reliable access control is crucial to a PDM system. This article has discussed the commonly used access control models, analyzed their advantages and disadvantages, and proposed a new Role and Object based access control model that suits the particular needs of a PDM system. The new model has been implemented in a commercial PDM system, which has demonstrated enhanced flexibility and convenience.

  10. Traditions of the Sun, One Model for Expanding Audience Access

    Science.gov (United States)

    Hawkins, I.; Paglierani, R.

    2006-12-01

    The Internet is a powerful tool with which to expand audience access, bringing students, teachers and the public to places and resources they might not otherwise visit or make use of. We will present Traditions of the Sun, an experiential Web site that invites exploration of the world's ancient observatories with special emphasis on Chaco Culture National Historic Park in the Four Corners region of the US and several sites in the Yucatan Peninsula in Mexico. Traditions of the Sun includes resources in English and Spanish along with a unique trilingual on-line book, "Traditions of the Sun, A Photographic Journal," containing explanatory text in Yucatec Maya as well. Traditions of the Sun offers rich opportunities for virtual visits to ancient sites used for solar observing while learning about current NASA research on the Sun and indigenous solar practices within a larger historical and cultural context. The site contains hundreds of photographs, historic images and rich multimedia to help tell the story of the Sun-Earth Connection. Visitors to the site can zoom in on the great Mayan cities of Chichen Itza, Uxmal, Dzibilchaltun, and Mayapan to learn about Mayan astronomy, history, culture, and science. They can also visit Chaco Canyon to watch sunrise over Pueblo Bonito on the summer solstice, take a virtual reality tour of the great kiva at Casa Rinconada or see panoramic vistas from Fajada Butte, an area which, for preservation purposes, is restricted to the public. Traditions of the Sun provides one model of how exploration and discovery can come to life for both formal and informal audiences via the Internet. Traditions of the Sun is a collaborative project between NASA's Sun-Earth Connection Education Forum, the National Park Service, Instituto National de Antropologia e Historia, Universidad Nacional Autonoma de Mexico, and Ideum.

  11. A Trusted Host's Authentication Access and Control Model Faced on User Action

    Institute of Scientific and Technical Information of China (English)

    ZHANG Miao; XU Guoai; HU Zhengming; YANG Yixian

    2006-01-01

    The conception of trusted network connection (TNC) is introduced, and the weakness of TNC to control user's action is analyzed. After this, the paper brings out a set of secure access and control model based on access, authorization and control, and related authentication protocol. At last the security of this model is analyzed. The model can improve TNC's security of user control and authorization.

  12. Population Balance Models: A useful complementary modelling framework for future WWTP modelling

    DEFF Research Database (Denmark)

    Nopens, Ingmar; Torfs, Elena; Ducoste, Joel

    2014-01-01

    Population Balance Models (PBMs) represent a powerful modelling framework for the description of the dynamics of properties that are characterised by statistical distributions. This has been demonstrated in many chemical engineering applications. Modelling efforts of several current and future unit...

  13. Population balance models: a useful complementary modelling framework for future WWTP modelling

    DEFF Research Database (Denmark)

    Nopens, Ingmar; Torfs, Elena; Ducoste, Joel

    2015-01-01

    Population balance models (PBMs) represent a powerful modelling framework for the description of the dynamics of properties that are characterised by distributions. This distribution of properties under transient conditions has been demonstrated in many chemical engineering applications. Modelling...

  14. Investigating accessibility indicators for feedback from a travel to a land use model

    OpenAIRE

    Thomas Nicolai; Kai Nagel

    2011-01-01

    Activity locations such as work locations or leisure facilities are not uniformly distributed geographically. Also, the travel access to different locations is not uniform. It is plausible to assume that locations with easier access to other activity locations are more attractive than locations with less access. In consequence, urban simulation models such as UrbanSim use accessibility measures, such as ``number of jobs with 30 minutes by car', for several of their submodels. A problem, howev...

  15. Evaluating the impact of climate policies on regional food availability and accessibility using an Integrated Assessment Model

    Science.gov (United States)

    Gilmore, E.; Cui, Y. R.; Waldhoff, S.

    2015-12-01

    Beyond 2015, eradicating hunger will remain a critical part of the global development agenda through the Sustainable Development Goals (SDG). Efforts to limit climate change through both mitigation of greenhouse gas emissions and land use policies may interact with food availability and accessibility in complex and unanticipated ways. Here, we develop projections of regional food accessibility to 2050 under the alternative futures outlined by the Shared Socioeconomic Pathways (SSPs) and under different climate policy targets and structures. We use the Global Change Assessment Model (GCAM), an integrated assessment model (IAM), for our projections. We calculate food access as the weighted average of consumption of five staples and the portion of income spend on those commodities and extend the GCAM calculated universal global producer price to regional consumer prices drawing on historical relationships of these prices. Along the SSPs, food access depends largely on expectations of increases in population and economic status. Under a more optimistic scenario, the pressures on food access from increasing demand and rising prices can be counterbalanced by faster economic development. Stringent climate policies that increase commodity prices, however, may hinder vulnerable regions, namely Sub-Saharan Africa, from achieving greater food accessibility.

  16. Modeling track access charge to enhance railway industry performance

    Science.gov (United States)

    Berawi, Mohammed Ali; Miraj, Perdana; Berawi, Abdur Rohim Boy; Susantono, Bambang; Leviakangas, Pekka; Radiansyah, Hendra

    2017-11-01

    Indonesia attempts to improve nation's competitiveness by increasing the quality and the availability of railway network. However, the infrastructure improperly managed by the operator in terms of the technical issue. One of the reasons for this problem is an unbalanced value of infrastructure charge. In 2000's track access charge and infrastructure maintenance and operation for Indonesia railways are equal and despite current formula of the infrastructure charge, issues of transparency and accountability still in question. This research aims to produce an alternative scheme of track access charge by considering marginal cost plus markup (MC+) approach. The research combines qualitative and quantitative method through an in-depth interview and financial analysis. The result will generate alternative formula of infrastructure charge in Indonesia's railway industry. The simulation also conducted to estimate track access charge for the operator and to forecast government support in terms of subsidy. The result is expected to enhance railway industry performance and competitiveness.

  17. Improving Access to Health Care Among New Zealand’s Maori Population

    Science.gov (United States)

    Ellison-Loschmann, Lis; Pearce, Neil

    2006-01-01

    The health status of indigenous peoples worldwide varies according to their unique historical, political, and social circumstances. Disparities in health between Maoris and non-Maoris have been evident for all of the colonial history of New Zealand. Explanations for these differences involve a complex mix of components associated with socioeconomic and lifestyle factors, availability of health care, and discrimination. Improving access to care is critical to addressing health disparities, and increasing evidence suggests that Maoris and non-Maoris differ in terms of access to primary and secondary health care services. We use 2 approaches to health service development to demonstrate how Maori-led initiatives are seeking to improve access to and quality of health care for Maoris. PMID:16507721

  18. Analysis of Genetic Diversity and Population Structure of Sesame Accessions from Africa and Asia as Major Centers of Its Cultivation

    Directory of Open Access Journals (Sweden)

    Komivi Dossa

    2016-04-01

    Full Text Available Sesame is an important oil crop widely cultivated in Africa and Asia. Understanding the genetic diversity of accessions from these continents is critical to designing breeding methods and for additional collection of sesame germplasm. To determine the genetic diversity in relation to geographical regions, 96 sesame accessions collected from 22 countries distributed over six geographic regions in Africa and Asia were genotyped using 33 polymorphic SSR markers. Large genetic variability was found within the germplasm collection. The total number of alleles was 137, averaging 4.15 alleles per locus. The accessions from Asia displayed more diversity than those from Africa. Accessions from Southern Asia (SAs, Eastern Asia (EAs, and Western Africa (WAf were highly diversified, while those from Western Asia (WAs, Northern Africa (NAf, and Southeastern Africa (SAf had the lowest diversity. The analysis of molecular variance revealed that more than 44% of the genetic variance was due to diversity among geographic regions. Five subpopulations, including three in Asia and two in Africa, were cross-identified through phylogenetic, PCA, and STRUCTURE analyses. Most accessions clustered in the same population based on their geographical origins. Our results provide technical guidance for efficient management of sesame genetic resources in breeding programs and further collection of sesame germplasm from these different regions.

  19. An open-access modeled passenger flow matrix for the global air network in 2010.

    Science.gov (United States)

    Huang, Zhuojie; Wu, Xiao; Garcia, Andres J; Fik, Timothy J; Tatem, Andrew J

    2013-01-01

    The expanding global air network provides rapid and wide-reaching connections accelerating both domestic and international travel. To understand human movement patterns on the network and their socioeconomic, environmental and epidemiological implications, information on passenger flow is required. However, comprehensive data on global passenger flow remain difficult and expensive to obtain, prompting researchers to rely on scheduled flight seat capacity data or simple models of flow. This study describes the construction of an open-access modeled passenger flow matrix for all airports with a host city-population of more than 100,000 and within two transfers of air travel from various publicly available air travel datasets. Data on network characteristics, city population, and local area GDP amongst others are utilized as covariates in a spatial interaction framework to predict the air transportation flows between airports. Training datasets based on information from various transportation organizations in the United States, Canada and the European Union were assembled. A log-linear model controlling the random effects on origin, destination and the airport hierarchy was then built to predict passenger flows on the network, and compared to the results produced using previously published models. Validation analyses showed that the model presented here produced improved predictive power and accuracy compared to previously published models, yielding the highest successful prediction rate at the global scale. Based on this model, passenger flows between 1,491 airports on 644,406 unique routes were estimated in the prediction dataset. The airport node characteristics and estimated passenger flows are freely available as part of the Vector-Borne Disease Airline Importation Risk (VBD-Air) project at: www.vbd-air.com/data.

  20. Dataflow models for shared memory access latency analysis

    NARCIS (Netherlands)

    Staschulat, Jan; Bekooij, Marco Jan Gerrit

    2009-01-01

    Performance analysis of applications in multi-core platforms is challenging because of temporal interference while accessing shared resources. Especially, memory arbiters introduce a non-constant delay which signicantly in uences the execution time of a task. In this paper, we selected a

  1. Evaluation of the challenges faced in increasing contraceptive access within a community college population.

    Science.gov (United States)

    Lamme, Jacqueline; Edelman, Alison; Padua, Emily; Jensen, Jeffrey T

    2017-01-01

    Research demonstrates removing barriers to access, decreasing costs and offering same-day placement of long-acting reversible contraception (LARC) increases contraceptive uptake in young women. For those in community college (CC), LARC utilization might reduce the risk of dropout and improve degree completion. We identified a local school who had documented an unmet need for on-campus services through a recent student assessment. We then established an on-campus, same day contraceptive clinic at the CC as part of a clinical trial. We found that students did not use the service even after multiple attempts to increase awareness and we ended the study. Here, we report lessons learned from attempting research in this environment in addition to results from a follow-up survey to determine why students did not access the clinical resource. Students reported that they already had good access to contraception and preferred to get their healthcare off-campus. This study demonstrates the complexities of studying highly focused interventions to influence access to care in the current health care environment with ever changing regulations. NCT02735551 . Registered April 6, 2016.

  2. Survivability of Existing Peripheral Intravenous Access Following Blood Sampling in a Pediatric Population.

    Science.gov (United States)

    O'Neil, Sheree W; Friesen, Mary Ann; Stanger, Debra; Trickey, Amber Williams

    2018-03-07

    Although pediatric patients report venipuncture as their most feared experience during hospitalization, blood sampling from peripheral intravenous accesses (PIVs) is not standard of care. Blood sampling from PIVs has long been considered by healthcare personnel to harm the access. In an effort to minimize painful procedures, pediatric nursing staff conducted a prospective, observational study to determine if blood sampling using existing PIVs resulted in the loss of the access. The ability to obtain the sample from the PIV was measured along with patient and PIV characteristics. Specimen collection using 100 existing PIVs was attempted on pediatric inpatients. Each PIV was observed for functionality, infiltration, occlusion, and dislodgement following collection and again in 4h. Frequencies of PIV loss and successful blood sampling were calculated. Patient age, PIV gauge, access site, and PIV age were evaluated for associations with successful sampling using chi-square tests, Fisher's exact tests, and logistic regression. PIV survivability was reported at 99%. The ability to obtain a complete specimen was reported at 76% and found to be significantly related to PIV age and site. Size of PIV and patient's age were not significantly related to successful sampling. Encouraging rates of PIV survivability and collectability suggest blood sampling from PIVs to be a valuable technique to minimize painful and distressful procedures. Nursing practice was changed in this pediatric department. Patients and families are saved the pain and distress of venipuncture. Nurses reported saving time and personal distress by avoiding the venipuncture procedure. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. A New Proposed Cost Model for List Accessing Problem using Buffering

    OpenAIRE

    Mohanty, Rakesh; Bhoi, Seetaya; Tripathy, Sasmita

    2011-01-01

    There are many existing well known cost models for the list accessing problem. The standard cost model developed by Sleator and Tarjan is most widely used. In this paper, we have made a comprehensive study of the existing cost models and proposed a new cost model for the list accessing problem. In our proposed cost model, for calculating the processing cost of request sequence using a singly linked list, we consider the access cost, matching cost and replacement cost. The cost of processing a...

  4. A linear model of population dynamics

    Science.gov (United States)

    Lushnikov, A. A.; Kagan, A. I.

    2016-08-01

    The Malthus process of population growth is reformulated in terms of the probability w(n,t) to find exactly n individuals at time t assuming that both the birth and the death rates are linear functions of the population size. The master equation for w(n,t) is solved exactly. It is shown that w(n,t) strongly deviates from the Poisson distribution and is expressed in terms either of Laguerre’s polynomials or a modified Bessel function. The latter expression allows for considerable simplifications of the asymptotic analysis of w(n,t).

  5. Task-and-role-based access-control model for computational grid

    Institute of Scientific and Technical Information of China (English)

    LONG Tao; HONG Fan; WU Chi; SUN Ling-li

    2007-01-01

    Access control in a grid environment is a challenging issue because the heterogeneous nature and independent administration of geographically dispersed resources in grid require access control to use fine-grained policies. We established a task-and-role-based access-control model for computational grid (CG-TRBAC model), integrating the concepts of role-based access control (RBAC) and task-based access control (TBAC). In this model, condition restrictions are defined and concepts specifically tailored to Workflow Management System are simplified or omitted so that role assignment and security administration fit computational grid better than traditional models; permissions are mutable with the task status and system variables, and can be dynamically controlled. The CG-TRBAC model is proved flexible and extendible. It can implement different control policies. It embodies the security principle of least privilege and executes active dynamic authorization. A task attribute can be extended to satisfy different requirements in a real grid system.

  6. A General Attribute and Rule Based Role-Based Access Control Model

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Growing numbers of users and many access control policies which involve many different resource attributes in service-oriented environments bring various problems in protecting resource. This paper analyzes the relationships of resource attributes to user attributes in all policies, and propose a general attribute and rule based role-based access control(GAR-RBAC) model to meet the security needs. The model can dynamically assign users to roles via rules to meet the need of growing numbers of users. These rules use different attribute expression and permission as a part of authorization constraints, and are defined by analyzing relations of resource attributes to user attributes in many access policies that are defined by the enterprise. The model is a general access control model, and can support many access control policies, and also can be used to wider application for service. The paper also describes how to use the GAR-RBAC model in Web service environments.

  7. Probabilistic models for access strategies to dynamic information elements

    DEFF Research Database (Denmark)

    Hansen, Martin Bøgsted; Olsen, Rasmus L.; Schwefel, Hans-Peter

    In various network services (e.g., routing and instances of context-sensitive networking) remote access to dynamically changing information elements is a required functionality. Three fundamentally different strategies for such access are investigated in this paper: (1) a reactive approach...... initiated by the requesting entity, and two versions of proactive approaches in which the entity that contains the information element actively propagates its changes to potential requesters, either (2) periodically or (3) triggered by changes of the information element. This paper develops probabilistic...... for information elements spread over a large number of network nodes are provided, which allow to draw conclusions on scalability properties. The impact of different distribution types for the network delays as well as for the time between changes of the information element on the mismatch probability...

  8. On the apllication of single specie dynamic population model | Iguda ...

    African Journals Online (AJOL)

    The Method of mathematical models of Malthus and Verhults were applied on ten years data collected from Magaram Poultry Farm to determine the nature of population growth, population decay or constant ... Keywords: Birth rate, sustainable population, overcrowding, harvesting, independent t-test and one way Anova.

  9. A Unified Access Model for Interconnecting Heterogeneous Wireless Networks

    Science.gov (United States)

    2015-05-01

    validation of the proposed network design for unified network access, and it lays the foundation for implementing a Software - Defined Networking ( SDN ...York (NY): Springer; 2014. Chapter 2, Software - defined networking ; p. 19–32. 5. Sharma S, Staessens D, Colle D, Pickavet M, Demeester P. A...demonstration of fast failure recovery in software defined networking . In: Korakis T, Zink M, Ott, M, editors. Testbeds and research infrastructure

  10. METHOD AND ABSTRACT MODEL FOR CONTROL AND ACCESS RIGHTS BY REQUESTS REDIRECTION

    Directory of Open Access Journals (Sweden)

    K. A. Shcheglov

    2015-11-01

    Full Text Available We have researched implementation problems of control and access rights of subjects to objects in modern computer systems. We have suggested access control method based on objects access requests redirection. The method possesses a distinctive feature as compared to discretional access control. In case when a subject needs to deny writing (object modification, it is not denied but redirected (access rights are not changed, but operation is performed with another object. This gives the possibility to implement access policies to system objects without breaking the system and applications operability, and share correctly access objects between subjects. This important property of suggested access control method enables to solve fundamentally new system objects securing problems like system resources virtualization aimed to protect system objects from users’ and applications attacks. We have created an abstract model, and it shows that this method (access control from subjects to objects based on requests redirection can be used as self-sufficient access control method, implementing any access control policy (from subjects to objects, thus being an alternative to discretional access control method.

  11. Doula Services Within a Healthy Start Program: Increasing Access for an Underserved Population

    OpenAIRE

    Thomas, Mary-Powel; Ammann, Gabriela; Brazier, Ellen; Noyes, Philip; Maybank, Aletha

    2017-01-01

    Purpose Women of color in the United States, particularly in high-poverty neighborhoods, experience high rates of poor birth outcomes, including cesarean section, preterm birth, low birthweight, and infant mortality. Doula care has been linked to improvements in many perinatal outcomes, but women of color and low-income women often face barriers in accessing doula support. Description To address this issue, the New York City Department of Health and Mental Hygiene’s Healthy Start Brooklyn int...

  12. An Approach to Enforcing Clark-Wilson Model in Role-based Access Control Model

    Institute of Scientific and Technical Information of China (English)

    LIANGBin; SHIWenchang; SUNYufang; SUNBo

    2004-01-01

    Using one security model to enforce another is a prospective solution to multi-policy support. In this paper, an approach to the enforcing Clark-Wilson data integrity model in the Role-based access control (RBAC) model is proposed. An enforcement construction with great feasibility is presented. In this construction, a direct way to enforce the Clark-Wilson model is provided, the corresponding relations among users, transformation procedures, and constrained data items are strengthened; the concepts of task and subtask are introduced to enhance the support to least-privilege. The proposed approach widens the applicability of RBAC. The theoretical foundation for adopting Clark-Wilson model in a RBAC system with small cost is offered to meet the requirements of multi-policy support and policy flexibility.

  13. Geographic Access Modeling of Emergency Obstetric and Neonatal Care in Kigoma Region, Tanzania: Transportation Schemes and Programmatic Implications.

    Science.gov (United States)

    Chen, Yi No; Schmitz, Michelle M; Serbanescu, Florina; Dynes, Michelle M; Maro, Godson; Kramer, Michael R

    2017-09-27

    Access to transportation is vital to reducing the travel time to emergency obstetric and neonatal care (EmONC) for managing complications and preventing adverse maternal and neonatal outcomes. This study examines the distribution of travel times to EmONC in Kigoma Region, Tanzania, using various transportation schemes, to estimate the proportion of live births (a proxy indicator of women needing delivery care) with poor geographic access to EmONC services. The 2014 Reproductive Health Survey of Kigoma Region identified 4 primary means of transportation used to travel to health facilities: walking, cycling, motorcycle, and 4-wheeled motor vehicle. A raster-based travel time model was used to map the 2-hour travel time catchment for each mode of transportation. Live birth density distributions were aggregated by travel time catchments, and by administrative council, to estimate the proportion of births with poor access. Of all live births in Kigoma Region, 13% occurred in areas where women can reach EmONC facilities within 2 hours on foot, 33% in areas that can be reached within 2 hours only by motorized vehicles, and 32% where it is impossible to reach EmONC facilities within 2 hours. Over 50% of births in 3 of the 8 administrative councils had poor estimated access. In half the councils, births with poor access could be reduced to no higher than 12% if all female residents had access to motorized vehicles. Significant differences in geographic access to EmONC in Kigoma Region, Tanzania, were observed both by location and by primary transportation type. As most of the population may only have good EmONC access when using mechanized or motorized vehicles, bicycles and motorcycles should be incorporated into the health transportation strategy. Collaboration between private transportation sectors and obstetric service providers could improve access to EmONC services among most populations. In areas where residents may not access EmONC facilities within 2 hours

  14. Using Direct Sub-Level Entity Access to Improve Nuclear Stockpile Simulation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Parker, Robert Y. [Brigham Young Univ., Provo, UT (United States)

    1999-08-01

    Direct sub-level entity access is a seldom-used technique in discrete-event simulation modeling that addresses the accessibility of sub-level entity information. The technique has significant advantages over more common, alternative modeling methods--especially where hierarchical entity structures are modeled. As such, direct sub-level entity access is often preferable in modeling nuclear stockpile, life-extension issues, an area to which it has not been previously applied. Current nuclear stockpile, life-extension models were demonstrated to benefit greatly from the advantages of direct sub-level entity access. In specific cases, the application of the technique resulted in models that were up to 10 times faster than functionally equivalent models where alternative techniques were applied. Furthermore, specific implementations of direct sub-level entity access were observed to be more flexible, efficient, functional, and scalable than corresponding implementations using common modeling techniques. Common modeling techniques (''unbatch/batch'' and ''attribute-copying'') proved inefficient and cumbersome in handling many nuclear stockpile modeling complexities, including multiple weapon sites, true defect analysis, and large numbers of weapon and subsystem types. While significant effort was required to enable direct sub-level entity access in the nuclear stockpile simulation models, the enhancements were worth the effort--resulting in more efficient, more capable, and more informative models that effectively addressed the complexities of the nuclear stockpile.

  15. Prospects of Genomic Prediction in the USDA Soybean Germplasm Collection: Historical Data Creates Robust Models for Enhancing Selection of Accessions

    Directory of Open Access Journals (Sweden)

    Diego Jarquin

    2016-08-01

    Full Text Available The identification and mobilization of useful genetic variation from germplasm banks for use in breeding programs is critical for future genetic gain and protection against crop pests. Plummeting costs of next-generation sequencing and genotyping is revolutionizing the way in which researchers and breeders interface with plant germplasm collections. An example of this is the high density genotyping of the entire USDA Soybean Germplasm Collection. We assessed the usefulness of 50K single nucleotide polymorphism data collected on 18,480 domesticated soybean (Glycine max accessions and vast historical phenotypic data for developing genomic prediction models for protein, oil, and yield. Resulting genomic prediction models explained an appreciable amount of the variation in accession performance in independent validation trials, with correlations between predicted and observed reaching up to 0.92 for oil and protein and 0.79 for yield. The optimization of training set design was explored using a series of cross-validation schemes. It was found that the target population and environment need to be well represented in the training set. Second, genomic prediction training sets appear to be robust to the presence of data from diverse geographical locations and genetic clusters. This finding, however, depends on the influence of shattering and lodging, and may be specific to soybean with its presence of maturity groups. The distribution of 7608 nonphenotyped accessions was examined through the application of genomic prediction models. The distribution of predictions of phenotyped accessions was representative of the distribution of predictions for nonphenotyped accessions, with no nonphenotyped accessions being predicted to fall far outside the range of predictions of phenotyped accessions.

  16. Survival models for harvest management of mourning dove populations

    Science.gov (United States)

    Otis, D.L.

    2002-01-01

    Quantitative models of the relationship between annual survival and harvest rate of migratory game-bird populations are essential to science-based harvest management strategies. I used the best available band-recovery and harvest data for mourning doves (Zenaida macroura) to build a set of models based on different assumptions about compensatory harvest mortality. Although these models suffer from lack of contemporary data, they can be used in development of an initial set of population models that synthesize existing demographic data on a management-unit scale, and serve as a tool for prioritization of population demographic information needs. Credible harvest management plans for mourning dove populations will require a long-term commitment to population monitoring and iterative population analysis.

  17. A general consumer-resource population model

    Science.gov (United States)

    Lafferty, Kevin D.; DeLeo, Giulio; Briggs, Cheryl J.; Dobson, Andrew P.; Gross, Thilo; Kuris, Armand M.

    2015-01-01

    Food-web dynamics arise from predator-prey, parasite-host, and herbivore-plant interactions. Models for such interactions include up to three consumer activity states (questing, attacking, consuming) and up to four resource response states (susceptible, exposed, ingested, resistant). Articulating these states into a general model allows for dissecting, comparing, and deriving consumer-resource models. We specify this general model for 11 generic consumer strategies that group mathematically into predators, parasites, and micropredators and then derive conditions for consumer success, including a universal saturating functional response. We further show how to use this framework to create simple models with a common mathematical lineage and transparent assumptions. Underlying assumptions, missing elements, and composite parameters are revealed when classic consumer-resource models are derived from the general model.

  18. Populational Growth Models Proportional to Beta Densities with Allee Effect

    Science.gov (United States)

    Aleixo, Sandra M.; Rocha, J. Leonel; Pestana, Dinis D.

    2009-05-01

    We consider populations growth models with Allee effect, proportional to beta densities with shape parameters p and 2, where the dynamical complexity is related with the Malthusian parameter r. For p>2, these models exhibit a population dynamics with natural Allee effect. However, in the case of 1models do not include this effect. In order to inforce it, we present some alternative models and investigate their dynamics, presenting some important results.

  19. The contribution of atom accessibility to site of metabolism models for cytochromes P450

    DEFF Research Database (Denmark)

    Rydberg, Patrik; Rostkowski, M.; Gloriam, D.E.

    2013-01-01

    Three different types of atom accessibility descriptors are investigated in relation to site of metabolism predictions. To enable the integration of local accessibility we have constructed 2DSASA, a method for the calculation of the atomic solvent accessible surface area that is independent of 3D...... coordinates. The method was implemented in the SMARTCyp site of metabolism prediction models and improved the results by up to 4 percentage points for nine cytochrome P450 isoforms. The final models are made available at http://www.farma.ku.dk/smartcyp.......Three different types of atom accessibility descriptors are investigated in relation to site of metabolism predictions. To enable the integration of local accessibility we have constructed 2DSASA, a method for the calculation of the atomic solvent accessible surface area that is independent of 3D...

  20. A model for optimizing file access patterns using spatio-temporal parallelism

    Energy Technology Data Exchange (ETDEWEB)

    Boonthanome, Nouanesengsy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Patchett, John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Geveci, Berk [Kitware Inc., Clifton Park, NY (United States); Ahrens, James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bauer, Andy [Kitware Inc., Clifton Park, NY (United States); Chaudhary, Aashish [Kitware Inc., Clifton Park, NY (United States); Miller, Ross G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shipman, Galen M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Williams, Dean N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-01-01

    For many years now, I/O read time has been recognized as the primary bottleneck for parallel visualization and analysis of large-scale data. In this paper, we introduce a model that can estimate the read time for a file stored in a parallel filesystem when given the file access pattern. Read times ultimately depend on how the file is stored and the access pattern used to read the file. The file access pattern will be dictated by the type of parallel decomposition used. We employ spatio-temporal parallelism, which combines both spatial and temporal parallelism, to provide greater flexibility to possible file access patterns. Using our model, we were able to configure the spatio-temporal parallelism to design optimized read access patterns that resulted in a speedup factor of approximately 400 over traditional file access patterns.

  1. Capability-based Access Control Delegation Model on the Federated IoT Network

    DEFF Research Database (Denmark)

    Anggorojati, Bayu; Mahalle, Parikshit N.; Prasad, Neeli R.

    2012-01-01

    Flexibility is an important property for general access control system and especially in the Internet of Things (IoT), which can be achieved by access or authority delegation. Delegation mechanisms in access control that have been studied until now have been intended mainly for a system that has...... no resource constraint, such as a web-based system, which is not very suitable for a highly pervasive system such as IoT. To this end, this paper presents an access delegation method with security considerations based on Capability-based Context Aware Access Control (CCAAC) model intended for federated...... machine-to-machine communication or IoT networks. The main idea of our proposed model is that the access delegation is realized by means of a capability propagation mechanism, and incorporating the context information as well as secure capability propagation under federated IoT environments. By using...

  2. Adding Value to Ecological Risk Assessment with Population Modeling

    DEFF Research Database (Denmark)

    Forbes, Valery E.; Calow, Peter; Grimm, Volker

    2011-01-01

    population models can provide a powerful basis for expressing ecological risks that better inform the environmental management process and thus that are more likely to be used by managers. Here we provide at least five reasons why population modeling should play an important role in bridging the gap between...

  3. Genetic diversity and a population structure analysis of accessions in the Chinese cowpea [Vigna unguiculata (L. Walp.] germplasm collection

    Directory of Open Access Journals (Sweden)

    Honglin Chen

    2017-10-01

    Full Text Available Cowpea (Vigna unguiculata is an important legume crop with diverse uses. The species is presently a minor crop, and evaluation of its genetic diversity has been very limited. In this study, a total of 200 genic and 100 genomic simple sequence repeat (SSR markers were developed from cowpea unigene and genome sequences, respectively. Among them, 27 genic and 27 genomic SSR markers were polymorphic and were used for assessment of genetic diversity and population structure in 105 selected cowpea accessions. A total of 155 alleles and 2.9 alleles per marker were identified, and the average polymorphic information content (PIC value was 0.3615. The average PIC of genomic SSRs (0.3996 was higher than that of genic SSRs (0.3235, and most of the polymorphic genomic SSRs were composed of di- and trinucleotide repeats (51.9% and 37.0% of all loci, respectively. The low level of detected genetic diversity may be attributed to a severe genetic bottleneck that occurred during the cowpea domestication process. The accessions were classified by structure and cluster analysis into four subgroups that correlated well with their geographic origins or collection sites. The classification results were also consistent with the results from principal coordinate analysis and can be used as a guide during future germplasm collection and selection of accessions as breeding materials for cultivar improvement. The newly developed genic and genomic SSR markers described in this study will be valuable genomic resources for the assessment of genetic diversity, population structure, evaluation of germplasm accessions, construction of genetic maps, identification of genes of interest, and application of marker-assisted selection in cowpea breeding programs.

  4. Population modelling to compare chronic external radiotoxicity between individual and population endpoints in four taxonomic groups.

    Science.gov (United States)

    Alonzo, Frédéric; Hertel-Aas, Turid; Real, Almudena; Lance, Emilie; Garcia-Sanchez, Laurent; Bradshaw, Clare; Vives I Batlle, Jordi; Oughton, Deborah H; Garnier-Laplace, Jacqueline

    2016-02-01

    In this study, we modelled population responses to chronic external gamma radiation in 12 laboratory species (including aquatic and soil invertebrates, fish and terrestrial mammals). Our aim was to compare radiosensitivity between individual and population endpoints and to examine how internationally proposed benchmarks for environmental radioprotection protected species against various risks at the population level. To do so, we used population matrix models, combining life history and chronic radiotoxicity data (derived from laboratory experiments and described in the literature and the FREDERICA database) to simulate changes in population endpoints (net reproductive rate R0, asymptotic population growth rate λ, equilibrium population size Neq) for a range of dose rates. Elasticity analyses of models showed that population responses differed depending on the affected individual endpoint (juvenile or adult survival, delay in maturity or reduction in fecundity), the considered population endpoint (R0, λ or Neq) and the life history of the studied species. Among population endpoints, net reproductive rate R0 showed the lowest EDR10 (effective dose rate inducing 10% effect) in all species, with values ranging from 26 μGy h(-1) in the mouse Mus musculus to 38,000 μGy h(-1) in the fish Oryzias latipes. For several species, EDR10 for population endpoints were lower than the lowest EDR10 for individual endpoints. Various population level risks, differing in severity for the population, were investigated. Population extinction (predicted when radiation effects caused population growth rate λ to decrease below 1, indicating that no population growth in the long term) was predicted for dose rates ranging from 2700 μGy h(-1) in fish to 12,000 μGy h(-1) in soil invertebrates. A milder risk, that population growth rate λ will be reduced by 10% of the reduction causing extinction, was predicted for dose rates ranging from 24 μGy h(-1) in mammals to 1800 μGy h(-1) in

  5. Transportation, Equity, and Communities at Risk : Refugee Population and Transportation Accessibility in Vermont.

    Science.gov (United States)

    2011-03-01

    This study suggests that transportation is one of the key issues and challenges facing newcomers to Vermont. For refugees and immigrants as for other members of the general population, being able to get to work, school, and medical appointments on ti...

  6. Surgical retroperitoneoscopic and transperitoneoscopic access in varicocelectomy: duplex scan results in pediatric population.

    Science.gov (United States)

    Mancini, Stefano; Bulotta, Anna Lavinia; Molinaro, Francesco; Ferrara, Francesco; Tommasino, Giulio; Messina, Mario

    2014-12-01

    This is a retrospective study to compare duplex scan results of laparoscopic Palomo's technique through retroperitoneal and transperitoneal approach for varicocelectomy in children. We statistically analyzed recurrence, testicular volume growth and complications. Surgical intervention was performed utilizing transperitoneoscopic (group A) or retroperitoneoscopic access (group B). Duplex scan control was performed after 12 months (T1), after 2 years (T2) and the last one at 18 years old in most patients. Statistical analysis was performed using the t-test for parametric data. Differences in proportions were evaluated using χ2 or Fisher's exact test. We treated 120 children (age range 10-17 years) who presented an asymptomatic IV grade of reflux, Coolsaet 1, associated with a left testicular hypotrophy in 36.6% of the cases (44 patients). No post-operative complications were verified. Duplex scan exam showed an increase of left testicular growth in both groups, with complete hypotrophy disappear in patients in both groups after 24 months. Hydrocele, diagnosed clinically and confirmed with duplex scan, was the most frequent post-operative complication (22/120 cases; 18.3%). This study showed the importance of duplex scan at all steps of this vascular pathology in children, and that there is no significantly difference in results between the two surgical techniques except for hydrocele in transperitoneoscopic access. Copyright © 2014 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

  7. Programmatic access to logical models in the Cell Collective modeling environment via a REST API.

    Science.gov (United States)

    Kowal, Bryan M; Schreier, Travis R; Dauer, Joseph T; Helikar, Tomáš

    2016-01-01

    Cell Collective (www.cellcollective.org) is a web-based interactive environment for constructing, simulating and analyzing logical models of biological systems. Herein, we present a Web service to access models, annotations, and simulation data in the Cell Collective platform through the Representational State Transfer (REST) Application Programming Interface (API). The REST API provides a convenient method for obtaining Cell Collective data through almost any programming language. To ensure easy processing of the retrieved data, the request output from the API is available in a standard JSON format. The Cell Collective REST API is freely available at http://thecellcollective.org/tccapi. All public models in Cell Collective are available through the REST API. For users interested in creating and accessing their own models through the REST API first need to create an account in Cell Collective (http://thecellcollective.org). thelikar2@unl.edu. Technical user documentation: https://goo.gl/U52GWo. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. A casemix model for estimating the impact of hospital access block on the emergency department.

    Science.gov (United States)

    Stuart, Peter

    2004-06-01

    To determine the ED activity and costs resulting from access block. A casemix model (AWOOS) was developed to measure activity due to access block. Using data from four hospitals between 1998 and 2002, ED activity was measured using the urgency and disposition group (UDG) casemix model and the AWOOS model with the purpose of determining the change in ED activity due to access block. Whilst the mean length of stay in ED (admitted patients) increased by 93% between 1998 and 2002, mean UDG activity increased by 0.63% compared to a mean increase in AWOOS activity of 24.5%. The 23.9% difference between UDG and AWOOS activity represents the (unmeasured) increase in ED activity and costs for the period 1998-2002 resulting from access block. The UDG system significantly underestimates the activity in EDs experiencing marked access block.

  9. Integral projection models for finite populations in a stochastic environment.

    Science.gov (United States)

    Vindenes, Yngvild; Engen, Steinar; Saether, Bernt-Erik

    2011-05-01

    Continuous types of population structure occur when continuous variables such as body size or habitat quality affect the vital parameters of individuals. These structures can give rise to complex population dynamics and interact with environmental conditions. Here we present a model for continuously structured populations with finite size, including both demographic and environmental stochasticity in the dynamics. Using recent methods developed for discrete age-structured models we derive the demographic and environmental variance of the population growth as functions of a continuous state variable. These two parameters, together with the expected population growth rate, are used to define a one-dimensional diffusion approximation of the population dynamics. Thus, a substantial reduction in complexity is achieved as the dynamics of the complex structured model can be described by only three population parameters. We provide methods for numerical calculation of the model parameters and demonstrate the accuracy of the diffusion approximation by computer simulation of specific examples. The general modeling framework makes it possible to analyze and predict future dynamics and extinction risk of populations with various types of structure, and to explore consequences of changes in demography caused by, e.g., climate change or different management decisions. Our results are especially relevant for small populations that are often of conservation concern.

  10. An open-population hierarchical distance sampling model

    Science.gov (United States)

    Sollmann, Rachel; Beth Gardner,; Richard B Chandler,; Royle, J. Andrew; T Scott Sillett,

    2015-01-01

    Modeling population dynamics while accounting for imperfect detection is essential to monitoring programs. Distance sampling allows estimating population size while accounting for imperfect detection, but existing methods do not allow for direct estimation of demographic parameters. We develop a model that uses temporal correlation in abundance arising from underlying population dynamics to estimate demographic parameters from repeated distance sampling surveys. Using a simulation study motivated by designing a monitoring program for island scrub-jays (Aphelocoma insularis), we investigated the power of this model to detect population trends. We generated temporally autocorrelated abundance and distance sampling data over six surveys, using population rates of change of 0.95 and 0.90. We fit the data generating Markovian model and a mis-specified model with a log-linear time effect on abundance, and derived post hoc trend estimates from a model estimating abundance for each survey separately. We performed these analyses for varying number of survey points. Power to detect population changes was consistently greater under the Markov model than under the alternatives, particularly for reduced numbers of survey points. The model can readily be extended to more complex demographic processes than considered in our simulations. This novel framework can be widely adopted for wildlife population monitoring.

  11. An open-population hierarchical distance sampling model.

    Science.gov (United States)

    Sollmann, Rahel; Gardner, Beth; Chandler, Richard B; Royle, J Andrew; Sillett, T Scott

    2015-02-01

    Modeling population dynamics while accounting for imperfect detection is essential to monitoring programs. Distance sampling allows estimating population size while accounting for imperfect detection, but existing methods do not allow for estimation of demographic parameters. We develop a model that uses temporal correlation in abundance arising from underlying population dynamics to estimate demographic parameters from repeated distance sampling surveys. Using a simulation study motivated by designing a monitoring program for Island Scrub-Jays (Aphelocoma insularis), we investigated the power of this model to detect population trends. We generated temporally autocorrelated abundance and distance sampling data over six surveys, using population rates of change of 0.95 and 0.90. We fit the data generating Markovian model and a mis-specified model with a log-linear time effect on abundance, and derived post hoc trend estimates from a model estimating abundance for each survey separately. We performed these analyses for varying numbers of survey points. Power to detect population changes was consistently greater under the Markov model than under the alternatives, particularly for reduced numbers of survey points. The model can readily be extended to more complex demographic processes than considered in our simulations. This novel framework can be widely adopted for wildlife population monitoring.

  12. Terrestrial population models for ecological risk assessment: A state-of-the-art review

    Science.gov (United States)

    Emlen, J.M.

    1989-01-01

    Few attempts have been made to formulate models for predicting impacts of xenobiotic chemicals on wildlife populations. However, considerable effort has been invested in wildlife optimal exploitation models. Because death from intoxication has a similar effect on population dynamics as death by harvesting, these management models are applicable to ecological risk assessment. An underlying Leslie-matrix bookkeeping formulation is widely applicable to vertebrate wildlife populations. Unfortunately, however, the various submodels that track birth, death, and dispersal rates as functions of the physical, chemical, and biotic environment are by their nature almost inevitably highly species- and locale-specific. Short-term prediction of one-time chemical applications requires only information on mortality before and after contamination. In such cases a simple matrix formulation may be adequate for risk assessment. But generally, risk must be projected over periods of a generation or more. This precludes generic protocols for risk assessment and also the ready and inexpensive predictions of a chemical's influence on a given population. When designing and applying models for ecological risk assessment at the population level, the endpoints (output) of concern must be carefully and rigorously defined. The most easily accessible and appropriate endpoints are (1) pseudoextinction (the frequency or probability of a population falling below a prespecified density), and (2) temporal mean population density. Spatial and temporal extent of predicted changes must be clearly specified a priori to avoid apparent contradictions and confusion.

  13. Using occupancy and population models to assess habitat conservation opportunities for an isolated carnivore population

    Science.gov (United States)

    Wayne Spencer; Heather Rustigian-Romsos; James Strittholt; Robert Scheller; William Zielinski; Richard Truex

    2011-01-01

    An isolated population of the fisher (Martes pennanti) in the southern Sierra Nevada, California, is threatened by small size and habitat alteration from wildfires, fuels management, and other factors. We assessed the population’s status and conservation options for its habitat using a spatially explicit population model coupled with a...

  14. Design and development of a customizable telemedicine platform for improving access to healthcare for underserved populations.

    Science.gov (United States)

    Goel, Neha A; Alam, Amal A; Eggert, Emily M R; Acharya, Soumyadipta

    2017-07-01

    Telemedicine offers a method to bridge the healthcare access gap in low and middle income countries (LMICs) by connecting providers with patients using appropriate technology. Here we describe the design and development of a novel modular telemedicine platform, Intelehealth, that would enable health systems to connect remote doctors with patients in rural clinics using a customizable Android-based platform and a cloud-based electronic health record system at the backend (OpenMRS). This open source platform enables task shifting of medically relevant information gathering by a local health worker, transmission of this information to a remote doctor, and a telephonic conversation between the doctor and the patient that subsequently allows for delivery of an appropriate therapeutic plan. Intelehealth is designed to operate on a low bandwidth internet environment, and will be tested and validated in rural health clinics in India.

  15. Implications of supermarket access, neighbourhood walkability and poverty rates for diabetes risk in an employee population.

    Science.gov (United States)

    Herrick, Cynthia J; Yount, Byron W; Eyler, Amy A

    2016-08-01

    Diabetes is a growing public health problem, and the environment in which people live and work may affect diabetes risk. The goal of the present study was to examine the association between multiple aspects of environment and diabetes risk in an employee population. This was a retrospective cross-sectional analysis. Home environment variables were derived using employees' zip code. Descriptive statistics were run on all individual- and zip-code-level variables, stratified by diabetes risk and worksite. A multivariable logistic regression analysis was then conducted to determine the strongest associations with diabetes risk. Data were collected from employee health fairs in a Midwestern health system, 2009-2012. The data set contains 25 227 unique individuals across four years of data. From this group, using an individual's first entry into the database, 15 522 individuals had complete data for analysis. The prevalence of high diabetes risk in this population was 2·3 %. There was significant variability in individual- and zip-code-level variables across worksites. From the multivariable analysis, living in a zip code with higher percentage of poverty and higher walk score was positively associated with high diabetes risk, while living in a zip code with higher supermarket density was associated with a reduction in high diabetes risk. Our study underscores the important relationship between poverty, home neighbourhood environment and diabetes risk, even in a relatively healthy employed population, and suggests a role for the employer in promoting health.

  16. Geographic distribution of need and access to health care in rural population: an ecological study in Iran

    Directory of Open Access Journals (Sweden)

    Najafi Behzad

    2011-09-01

    Full Text Available Abstract Introduction Equity in access to and utilization of health services is a common goal of policy-makers in most countries. The current study aimed to evaluate the distribution of need and access to health care services among Iran's rural population between 2006 and 2009. Methods Census data on population's characteristics in each province were obtained from the Statistical Centre of Iran and National Organization for civil registration. Data about the Rural Health Houses (RHHs were obtained from the Ministry of Health. The Health Houses-to-rural population ratio (RHP, crude birth rate (CBR and crude mortality rate (CMR in rural population were calculated in order to compare their distribution among the provinces. Lorenz curves of RHHs, CMR and CBR were plotted and their decile ratio, Gini Index and Index of Dissimilarity were calculated. Moreover, Spearman rank-order correlation was used to examine the relation between RHHs and CMR and CBR. Results There were substantial differences in RHHs, CMR and CBR across the provinces. CMR and CBR experienced changes toward more equal distributions between 2006 and 2009, while inverse trend was seen for RHHs. Excluding three provinces with markedly changes in data between 2006 and 2009 as outliers, did not change observed trends. Moreover; there was a significant positive relationship between CMR and RHP in 2009 and a significant negative association between CBR and RHP in 2006 and 2009. When three provinces with outliers were excluded, these significant associations were disappeared. Conclusion Results showed that there were significant variations in the distribution of RHHs, CMR and CBR across the country. Moreover, the distribution of RHHs did not reflect the needs for health care in terms of CMR and CBR in the study period.

  17. Environmental whole-genome amplification to access microbial populations in contaminated sediments

    Energy Technology Data Exchange (ETDEWEB)

    Abulencia, Carl B [Diversa Corporation; Wyborski, Denise L. [Diversa Corporation; Garcia, Joseph A. [Diversa Corporation; Podar, Mircea [ORNL; Chen, Wenqiong [Diversa Corporation; Chang, Sherman H. [Diversa Corporation; Chang, Hwai W. [Diversa Corporation; Watson, David B [ORNL; Brodie, Eoin L. [Lawrence Berkeley National Laboratory (LBNL); Hazen, Terry [Lawrence Berkeley National Laboratory (LBNL); Keller, Martin [ORNL

    2006-05-01

    Low-biomass samples from nitrate and heavy metal contaminated soils yield DNA amounts that have limited use for direct, native analysis and screening. Multiple displacement amplification (MDA) using {phi}29 DNA polymerase was used to amplify whole genomes from environmental, contaminated, subsurface sediments. By first amplifying the genomic DNA (gDNA), biodiversity analysis and gDNA library construction of microbes found in contaminated soils were made possible. The MDA method was validated by analyzing amplified genome coverage from approximately five Escherichia coli cells, resulting in 99.2% genome coverage. The method was further validated by confirming overall representative species coverage and also an amplification bias when amplifying from a mix of eight known bacterial strains. We extracted DNA from samples with extremely low cell densities from a U.S. Department of Energy contaminated site. After amplification, small-subunit rRNA analysis revealed relatively even distribution of species across several major phyla. Clone libraries were constructed from the amplified gDNA, and a small subset of clones was used for shotgun sequencing. BLAST analysis of the library clone sequences showed that 64.9% of the sequences had significant similarities to known proteins, and 'clusters of orthologous groups' (COG) analysis revealed that more than half of the sequences from each library contained sequence similarity to known proteins. The libraries can be readily screened for native genes or any target of interest. Whole-genome amplification of metagenomic DNA from very minute microbial sources, while introducing an amplification bias, will allow access to genomic information that was not previously accessible.

  18. Periodic solutions of nonautonomous differential systems modeling obesity population

    Energy Technology Data Exchange (ETDEWEB)

    Arenas, Abraham J. [Departamento de Matematicas y Estadistica, Universidad de Cordoba Monteria (Colombia)], E-mail: aarenas@sinu.unicordoba.edu.co; Gonzalez-Parra, Gilberto [Departamento de Calculo, Universidad de los Andes, Merida (Venezuela, Bolivarian Republic of)], E-mail: gcarlos@ula.ve; Jodar, Lucas [Instituto de Matematica Multidisciplinar, Universidad Politecnica de Valencia Edificio 8G, 2o, 46022 Valencia (Spain)], E-mail: ljodar@imm.upv.es

    2009-10-30

    In this paper we study the periodic behaviour of the solutions of a nonautonomous model for obesity population. The mathematical model represented by a nonautonomous system of nonlinear ordinary differential equations is used to model the dynamics of obese populations. Numerical simulations suggest periodic behaviour of subpopulations solutions. Sufficient conditions which guarantee the existence of a periodic positive solution are obtained using a continuation theorem based on coincidence degree theory.

  19. Periodic solutions of nonautonomous differential systems modeling obesity population

    International Nuclear Information System (INIS)

    Arenas, Abraham J.; Gonzalez-Parra, Gilberto; Jodar, Lucas

    2009-01-01

    In this paper we study the periodic behaviour of the solutions of a nonautonomous model for obesity population. The mathematical model represented by a nonautonomous system of nonlinear ordinary differential equations is used to model the dynamics of obese populations. Numerical simulations suggest periodic behaviour of subpopulations solutions. Sufficient conditions which guarantee the existence of a periodic positive solution are obtained using a continuation theorem based on coincidence degree theory.

  20. Multi-model-based Access Control in Construction Projects

    Directory of Open Access Journals (Sweden)

    Frank Hilbert

    2012-04-01

    Full Text Available During the execution of large scale construction projects performed by Virtual Organizations (VO, relatively complex technical models have to be exchanged between the VO members. For linking the trade and transfer of these models, a so-called multi-model container format was developed. Considering the different skills and tasks of the involved partners, it is not necessary for them to know all the models in every technical detailing. Furthermore, the model size can lead to a delay in communication. In this paper an approach is presented for defining model cut-outs according to the current project context. Dynamic dependencies to the project context as well as static dependencies on the organizational structure are mapped in a context-sensitive rule. As a result, an approach for dynamic filtering of multi-models is obtained which ensures, together with a filtering service, that the involved VO members get a simplified view of complex multi-models as well as sufficient permissions depending on their tasks.

  1. Stimulus-dependent maximum entropy models of neural population codes.

    Directory of Open Access Journals (Sweden)

    Einat Granot-Atedgi

    Full Text Available Neural populations encode information about their stimulus in a collective fashion, by joint activity patterns of spiking and silence. A full account of this mapping from stimulus to neural activity is given by the conditional probability distribution over neural codewords given the sensory input. For large populations, direct sampling of these distributions is impossible, and so we must rely on constructing appropriate models. We show here that in a population of 100 retinal ganglion cells in the salamander retina responding to temporal white-noise stimuli, dependencies between cells play an important encoding role. We introduce the stimulus-dependent maximum entropy (SDME model-a minimal extension of the canonical linear-nonlinear model of a single neuron, to a pairwise-coupled neural population. We find that the SDME model gives a more accurate account of single cell responses and in particular significantly outperforms uncoupled models in reproducing the distributions of population codewords emitted in response to a stimulus. We show how the SDME model, in conjunction with static maximum entropy models of population vocabulary, can be used to estimate information-theoretic quantities like average surprise and information transmission in a neural population.

  2. [Population projection and its principal components: the future model of population in the province of Alicante].

    Science.gov (United States)

    Norman Mora, E

    1994-01-01

    "In this article we analyze the different demographic patterns defining the population in the province of Alicante [Spain]. The behaviour of the demographic factors in the past and in the present is studied here, and a series of models are put into practice in order to foresee the future pattern of population.... The result shows either the effect of a possible ageing in an already aged population, as is the case of the province of Alicante, or what the job market would have to endure if the above mentioned ageing took place, increased by the possibility of an inmigration of an older population." (SUMMARY IN ENG AND FRE) excerpt

  3. Modeling Approaches for Describing Microbial Population Heterogeneity

    DEFF Research Database (Denmark)

    Lencastre Fernandes, Rita

    environmental conditions. Three cases are presented and discussed in this thesis. Common to all is the use of S. cerevisiae as model organism, and the use of cell size and cell cycle position as single-cell descriptors. The first case focuses on the experimental and mathematical description of a yeast...

  4. Population modelling to compare chronic external radiotoxicity between individual and population endpoints in four taxonomic groups

    International Nuclear Information System (INIS)

    Alonzo, Frédéric; Hertel-Aas, Turid; Real, Almudena; Lance, Emilie; Garcia-Sanchez, Laurent; Bradshaw, Clare; Vives i Batlle, Jordi; Oughton, Deborah H.; Garnier-Laplace, Jacqueline

    2016-01-01

    In this study, we modelled population responses to chronic external gamma radiation in 12 laboratory species (including aquatic and soil invertebrates, fish and terrestrial mammals). Our aim was to compare radiosensitivity between individual and population endpoints and to examine how internationally proposed benchmarks for environmental radioprotection protected species against various risks at the population level. To do so, we used population matrix models, combining life history and chronic radiotoxicity data (derived from laboratory experiments and described in the literature and the FREDERICA database) to simulate changes in population endpoints (net reproductive rate R_0, asymptotic population growth rate λ, equilibrium population size N_e_q) for a range of dose rates. Elasticity analyses of models showed that population responses differed depending on the affected individual endpoint (juvenile or adult survival, delay in maturity or reduction in fecundity), the considered population endpoint (R_0, λ or N_e_q) and the life history of the studied species. Among population endpoints, net reproductive rate R_0 showed the lowest EDR_1_0 (effective dose rate inducing 10% effect) in all species, with values ranging from 26 μGy h"−"1 in the mouse Mus musculus to 38,000 μGy h"−"1 in the fish Oryzias latipes. For several species, EDR_1_0 for population endpoints were lower than the lowest EDR_1_0 for individual endpoints. Various population level risks, differing in severity for the population, were investigated. Population extinction (predicted when radiation effects caused population growth rate λ to decrease below 1, indicating that no population growth in the long term) was predicted for dose rates ranging from 2700 μGy h"−"1 in fish to 12,000 μGy h"−"1 in soil invertebrates. A milder risk, that population growth rate λ will be reduced by 10% of the reduction causing extinction, was predicted for dose rates ranging from 24 μGy h"−"1

  5. Modeling the brain morphology distribution in the general aging population

    Science.gov (United States)

    Huizinga, W.; Poot, D. H. J.; Roshchupkin, G.; Bron, E. E.; Ikram, M. A.; Vernooij, M. W.; Rueckert, D.; Niessen, W. J.; Klein, S.

    2016-03-01

    Both normal aging and neurodegenerative diseases such as Alzheimer's disease cause morphological changes of the brain. To better distinguish between normal and abnormal cases, it is necessary to model changes in brain morphology owing to normal aging. To this end, we developed a method for analyzing and visualizing these changes for the entire brain morphology distribution in the general aging population. The method is applied to 1000 subjects from a large population imaging study in the elderly, from which 900 were used to train the model and 100 were used for testing. The results of the 100 test subjects show that the model generalizes to subjects outside the model population. Smooth percentile curves showing the brain morphology changes as a function of age and spatiotemporal atlases derived from the model population are publicly available via an interactive web application at agingbrain.bigr.nl.

  6. Model for Measuring the Entrepreneurship of the Population

    Directory of Open Access Journals (Sweden)

    Šarūnė Beinoraitė

    2014-09-01

    Full Text Available Population entrepreneurship is an important factor in the progress of economic development. This paper proposes a model of entrepreneurship measurement for comparing the level of entrepreneurship. The model consists of two main components, including criteria for the selection and determination of entrepreneurship by adapting the multi­criteria evaluation method TOPSIS. The most important criteria for identifying entrepreneurship cover the dynamics of the unemployment rate, the population of personal characteristics, geographical location, broadband Internet penetration per 1000 inhabitants, issued business licenses per thousand population, competitiveness, innovation, registered enterprises per thousand population, the promotion of a entrepreneurship program, the average wage level, the number of loans taken for business per thousand population, the number of bankrupt enterprises per thousand population, the level of education, the subscription of newspapers and magazines on business.

  7. Enhancing Access to Scientific Models through Standard Web Services, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to investigate the feasibility and value of the "Software as a Service" paradigm in facilitating access to Earth Science numerical models. We envision...

  8. The critical domain size of stochastic population models.

    Science.gov (United States)

    Reimer, Jody R; Bonsall, Michael B; Maini, Philip K

    2017-02-01

    Identifying the critical domain size necessary for a population to persist is an important question in ecology. Both demographic and environmental stochasticity impact a population's ability to persist. Here we explore ways of including this variability. We study populations with distinct dispersal and sedentary stages, which have traditionally been modelled using a deterministic integrodifference equation (IDE) framework. Individual-based models (IBMs) are the most intuitive stochastic analogues to IDEs but yield few analytic insights. We explore two alternate approaches; one is a scaling up to the population level using the Central Limit Theorem, and the other a variation on both Galton-Watson branching processes and branching processes in random environments. These branching process models closely approximate the IBM and yield insight into the factors determining the critical domain size for a given population subject to stochasticity.

  9. Changes in Access to Health Services of the Immigrant and Native-Born Population in Spain in the Context of Economic Crisis †

    Science.gov (United States)

    Garcia-Subirats, Irene; Vargas, Ingrid; Sanz-Barbero, Belén; Malmusi, Davide; Ronda, Elena; Ballesta, Mónica; Vázquez, María Luisa

    2014-01-01

    Aim: To analyze changes in access to health care and its determinants in the immigrant and native-born populations in Spain, before and during the economic crisis. Methods: Comparative analysis of two iterations of the Spanish National Health Survey (2006 and 2012). Outcome variables were: unmet need and use of different healthcare levels; explanatory variables: need, predisposing and enabling factors. Multivariate models were performed (1) to compare outcome variables in each group between years, (2) to compare outcome variables between both groups within each year, and (3) to determine the factors associated with health service use for each group and year. Results: unmet healthcare needs decreased in 2012 compared to 2006; the use of health services remained constant, with some changes worth highlighting, such as the decline in general practitioner visits among autochthons and a narrowed gap in specialist visits between the two populations. The factors associated with health service use in 2006 remained constant in 2012. Conclusion: Access to healthcare did not worsen, possibly due to the fact that, until 2012, the national health system may have cushioned the deterioration of social determinants as a consequence of the financial crisis. Further studies are necessary to evaluate the effects of health policy responses to the crisis after 2012. PMID:25272078

  10. Changes in Access to Health Services of the Immigrant and Native-Born Population in Spain in the Context of Economic Crisis

    Directory of Open Access Journals (Sweden)

    Irene Garcia-Subirats

    2014-09-01

    Full Text Available Aim: To analyze changes in access to health care and its determinants in the immigrant and native-born populations in Spain, before and during the economic crisis. Methods: Comparative analysis of two iterations of the Spanish National Health Survey (2006 and 2012. Outcome variables were: unmet need and use of different healthcare levels; explanatory variables: need, predisposing and enabling factors. Multivariate models were performed (1 to compare outcome variables in each group between years, (2 to compare outcome variables between both groups within each year, and (3 to determine the factors associated with health service use for each group and year. Results: unmet healthcare needs decreased in 2012 compared to 2006; the use of health services remained constant, with some changes worth highlighting, such as the decline in general practitioner visits among autochthons and a narrowed gap in specialist visits between the two populations. The factors associated with health service use in 2006 remained constant in 2012. Conclusion: Access to healthcare did not worsen, possibly due to the fact that, until 2012, the national health system may have cushioned the deterioration of social determinants as a consequence of the financial crisis. Further studies are necessary to evaluate the effects of health policy responses to the crisis after 2012.

  11. Coopetitive Business Models in Future Mobile Broadband with Licensed Shared Access (LSA)

    OpenAIRE

    P. Ahokangas; M. Matinmikko; I. Atkova; L.F. Minervini; S. Yrjölä; M. Mustonen

    2016-01-01

    Spectrum scarcity forces mobile network operators (MNOs) providing mobile broadband services to develop new business models that address spectrum sharing. It engages MNOs into coopetitive relationship with incumbents. Licensed Shared Access (LSA) concept complements traditional licensing and helps MNOs to access new spectrum bands on a shared basis. This paper discusses spectrum sharing with LSA from business perspective. It describes how coopetition and business model are linked conceptually...

  12. Two Populations Mean-Field Monomer-Dimer Model

    Science.gov (United States)

    Alberici, Diego; Mingione, Emanuele

    2018-04-01

    A two populations mean-field monomer-dimer model including both hard-core and attractive interactions between dimers is considered. The pressure density in the thermodynamic limit is proved to satisfy a variational principle. A detailed analysis is made in the limit of one population is much smaller than the other and a ferromagnetic mean-field phase transition is found.

  13. A Role for M-Matrices in Modelling Population Growth

    Science.gov (United States)

    James, Glyn; Rumchev, Ventsi

    2006-01-01

    Adopting a discrete-time cohort-type model to represent the dynamics of a population, the problem of achieving a desired total size of the population under a balanced growth (contraction) and the problem of maintaining the desired size, once achieved, are studied. Properties of positive-time systems and M-matrices are used to develop the results,…

  14. An age structured model for obesity prevalence dynamics in populations

    Directory of Open Access Journals (Sweden)

    Gilberto González Parra

    2010-08-01

    Full Text Available Objective. Modeling the correlation of the development of obesity in a population with age and time and predict the dynamics of the correlation of the development of obesity in a population with age and time under different scenarios in Valencia (Spain. Materials and methods. An age structured mathematical model is used to describe the future dynamics of obesity prevalence for different ages in human population with excess weight. Simulation of the model with parameters estimated using the Health Survey of the Region of Valencia 2000 (4.319 interviews and Health Survey of the Region of Valencia 2005 (4.012 interviews. The model considers only overweight and obese populations since these subpopulations are the most relevant on obesity health concern. Results. The model allows predicting and studying the prevalence of obesity for each age. Results showed an increasing trend of obesity in the following years in well accordance with the trend observed in several countries. Conclusions. Based on the numerical simulations it is possible to conclude that the age structured mathematical model is suitable to forecast the obesity epidemic in each age group in different countries. Additionally, this type of models may be applied to study other characteristics of other populations such animal populations.

  15. Parameter Estimates in Differential Equation Models for Population Growth

    Science.gov (United States)

    Winkel, Brian J.

    2011-01-01

    We estimate the parameters present in several differential equation models of population growth, specifically logistic growth models and two-species competition models. We discuss student-evolved strategies and offer "Mathematica" code for a gradient search approach. We use historical (1930s) data from microbial studies of the Russian biologist,…

  16. Safety of Mixed Model Access Control in a Multilevel System

    Science.gov (United States)

    2014-06-01

    42  H.  FIREWALL AND IPS LANGUAGES...Research Laboratory AIS automated information system ANOA advance notice of arrival APT advanced persistent threat BFM boundary flow modeling...of Investigation FW firewall GENSER general service xvi GUI graphical user interface HAG high-assurance guard HGS high-grade service H-H-H High

  17. Supporting Indoor Navigation Using Access Rights to Spaces Based on Combined Use of IndoorGML and LADM Models

    Directory of Open Access Journals (Sweden)

    Abdullah Alattas

    2017-11-01

    of this paper. The main purpose of the combined use model is to support the indoor navigation, but could also support different applications, such as the maintenance and facility management work, by computing the cleaning cost based on the space floor area. The main contributions of this paper are: a solution for the combined use of IndoorGML-LADM model, a conceptual enhancement of LADM by the refinement of the LA_Party package with specialization for staff and student (groups, and the assessment of the model by converting sample data (from two complex university buildings into the model, and conducting actual access-rights aware navigation, based on the populated model.

  18. Population models of burrowing mayfly recolonization in Western Lake Erie

    Science.gov (United States)

    Madenjian, C.P.; Schloesser, D.W.; Krieger, K.A.

    1998-01-01

    Burrowing mayflies, Hexagenia spp. (H. limbata and H. rigida), began recolonizing western Lake Erie during the 1990s. Survey data for mayfly nymph densities indicated that the population experienced exponential growth between 1991 and 1997. To predict the time to full recovery of the mayfly population, we fitted logistic models, ranging in carrying capacity from 600 to 2000 nymphs/m2, to these survey data. Based on the fitted logistic curves, we forecast that the mayfly population in western Lake Erie would achieve full recovery between years 1998 and 2000, depending on the carrying capacity of the western basin. Additionally, we estimated the mortality rate of nymphs in western Lake Erie during 1994 and then applied an age-based matrix model to the mayfly population. The results of the matrix population modeling corroborated the exponential growth model application in that both methods yielded an estimate of the population growth rate, r, in excess of 0.8 yr-1. This was the first evidence that mayfly populations are capable of recolonizing large aquatic ecosystems at rates comparable with those observed in much smaller lentic ecosystems. Our model predictions should prove valuable to managers of power plant facilities along the western basin in planning for mayfly emergences and to managers of the yellow perch (Perca flavescens) fishery in western Lake Erie.

  19. Predicting population extinction or disease outbreaks with stochastic models

    Directory of Open Access Journals (Sweden)

    Linda J. S. Allen

    2017-01-01

    Full Text Available Models of exponential growth, logistic growth and epidemics are common applications in undergraduate differential equation courses. The corresponding stochastic models are not part of these courses, although when population sizes are small their behaviour is often more realistic and distinctly different from deterministic models. For example, the randomness associated with births and deaths may lead to population extinction even in an exponentially growing population. Some background in continuous-time Markov chains and applications to populations, epidemics and cancer are presented with a goal to introduce this topic into the undergraduate mathematics curriculum that will encourage further investigation into problems on conservation, infectious diseases and cancer therapy. MATLAB programs for graphing sample paths of stochastic models are provided in the Appendix.

  20. The macroeconomic consequences of renouncing to universal access to antiretroviral treatment for HIV in Africa: a micro-simulation model.

    Science.gov (United States)

    Ventelou, Bruno; Arrighi, Yves; Greener, Robert; Lamontagne, Erik; Carrieri, Patrizia; Moatti, Jean-Paul

    2012-01-01

    Previous economic literature on the cost-effectiveness of antiretroviral treatment (ART) programs has been mainly focused on the microeconomic consequences of alternative use of resources devoted to the fight against the HIV pandemic. We rather aim at forecasting the consequences of alternative scenarios for the macroeconomic performance of countries. We used a micro-simulation model based on individuals aged 15-49 selected from nationally representative surveys (DHS for Cameroon, Tanzania and Swaziland) to compare alternative scenarios : 1-freezing of ART programs to current levels of access, 2- universal access (scaling up to 100% coverage by 2015, with two variants defining ART eligibility according to previous or current WHO guidelines). We introduced an "artificial" ageing process by programming methods. Individuals could evolve through different health states: HIV negative, HIV positive (with different stages of the syndrome). Scenarios of ART procurement determine this dynamics. The macroeconomic impact is obtained using sample weights that take into account the resulting age-structure of the population in each scenario and modeling of the consequences on total growth of the economy. Increased levels of ART coverage result in decreasing HIV incidence and related mortality. Universal access to ART has a positive impact on workers' productivity; the evaluations performed for Swaziland and Cameroon show that universal access would imply net cost-savings at the scale of the society, when the full macroeconomic consequences are introduced in the calculations. In Tanzania, ART access programs imply a net cost for the economy, but 70% of costs are covered by GDP gains at the 2034 horizon, even in the extended coverage option promoted by WHO guidelines initiating ART at levels of 350 cc/mm(3) CD4 cell counts. Universal Access ART scaling-up strategies, which are more costly in the short term, remain the best economic choice in the long term. Renouncing or

  1. Modelling the Dynamics of an Aedes albopictus Population

    Directory of Open Access Journals (Sweden)

    Thomas Anung Basuki

    2010-08-01

    Full Text Available We present a methodology for modelling population dynamics with formal means of computer science. This allows unambiguous description of systems and application of analysis tools such as simulators and model checkers. In particular, the dynamics of a population of Aedes albopictus (a species of mosquito and its modelling with the Stochastic Calculus of Looping Sequences (Stochastic CLS are considered. The use of Stochastic CLS to model population dynamics requires an extension which allows environmental events (such as changes in the temperature and rainfalls to be taken into account. A simulator for the constructed model is developed via translation into the specification language Maude, and used to compare the dynamics obtained from the model with real data.

  2. A general modeling framework for describing spatially structured population dynamics

    Science.gov (United States)

    Sample, Christine; Fryxell, John; Bieri, Joanna; Federico, Paula; Earl, Julia; Wiederholt, Ruscena; Mattsson, Brady; Flockhart, Tyler; Nicol, Sam; Diffendorfer, James E.; Thogmartin, Wayne E.; Erickson, Richard A.; Norris, D. Ryan

    2017-01-01

    Variation in movement across time and space fundamentally shapes the abundance and distribution of populations. Although a variety of approaches model structured population dynamics, they are limited to specific types of spatially structured populations and lack a unifying framework. Here, we propose a unified network-based framework sufficiently novel in its flexibility to capture a wide variety of spatiotemporal processes including metapopulations and a range of migratory patterns. It can accommodate different kinds of age structures, forms of population growth, dispersal, nomadism and migration, and alternative life-history strategies. Our objective was to link three general elements common to all spatially structured populations (space, time and movement) under a single mathematical framework. To do this, we adopt a network modeling approach. The spatial structure of a population is represented by a weighted and directed network. Each node and each edge has a set of attributes which vary through time. The dynamics of our network-based population is modeled with discrete time steps. Using both theoretical and real-world examples, we show how common elements recur across species with disparate movement strategies and how they can be combined under a unified mathematical framework. We illustrate how metapopulations, various migratory patterns, and nomadism can be represented with this modeling approach. We also apply our network-based framework to four organisms spanning a wide range of life histories, movement patterns, and carrying capacities. General computer code to implement our framework is provided, which can be applied to almost any spatially structured population. This framework contributes to our theoretical understanding of population dynamics and has practical management applications, including understanding the impact of perturbations on population size, distribution, and movement patterns. By working within a common framework, there is less chance

  3. Model for Measuring the Entrepreneurship of the Population

    OpenAIRE

    Drejeris, Rolandas; Beinoraitė, Šarūnė

    2014-01-01

    Population entrepreneurship is an important factor in the progress of economic development. This paper proposes a model of entrepreneurship measurement for comparing the level of entrepreneurship. The model consists of two main components, including criteria for the selection and determination of entrepreneurship by adapting the multi­criteria evaluation method TOPSIS. The most important criteria for identifying entrepreneurship cover the dynamics of the unemployment rate, the population of p...

  4. The Degree of Accessibility to Health Care – Issues Concerning the North-Eastern Population of Romania

    Directory of Open Access Journals (Sweden)

    Alina Mareci

    2008-05-01

    Full Text Available This study is analysing the population accessibly to the sanitary infrastructure in the North-East region of Romania, namely the six component counties of Bacu, Botoani, Iai, Neam, Suceava and Vaslui. Due to lack of basic sanitary infrastructure when it comes to regional general medical centres (called dispensaries, the population is forced to travel large distances in order to benefit of medical assistance. The hospital infrastructure is unbalanced in terms of territorial distribution. The highly populated urban settlements are usually equipped with one or more hospital unit(s being located along the national road E85 and the adjacent national roads, fulfilling in most cases municipal roles or holding vital social and economic importance for the region. The longer distances the patients are forced to travel for medical assistance the higher health costs due to the additional travel costs the person has to undertake. One direct result of this travelling is overcrowded hospitals in the targeted areas which in its turn may have negative impacts on the quality of services provided and on the amount of time the people need to spend in that facility.

  5. The author who wasn't there? Fairness and attribution in publications following access to population biobanks.

    Science.gov (United States)

    Kleiderman, Erika; Pack, Amy; Borry, Pascal; Zawati, Ma'n

    2018-01-01

    We conducted a document analysis that explored publication ethics and authorship in the context of population biobanks from both a theoretical (e.g. normative documents) and practical (e.g. biobank-specific documentation) perspective. The aim was to provide an overview of the state of authorship attribution in population biobanks and attempt to fill the gap in discussions around the issue. Our findings demonstrate that the most common approach adopted in both the normative and biobank-specific documentation is acknowledgment. A co-authorship approach was second and highlighted concerns surrounding the fairness of imposing authorship of the scientific leadership as a condition to access data and biosamples, as well as the alignment with the International Committee of Medical Journal Editors' criteria such as what is deemed a significant contribution and how to ensure accountability. Based on these findings, we propose a three-prong approach, that may be cumulative, to address the issue of authorship attribution in the context of population biobanks, namely 1) the biobank should be appropriately acknowledged; 2) an invitation for co-authorship should be made based on the spirit of collaboration and provided a substantial contribution has been made; and 3) a citation/referencing option should be available.

  6. Hyper-Uricemia and Gouty Access in the Adult Population of the Southeast of Gabon: Biochemical Aspects

    Directory of Open Access Journals (Sweden)

    Guy Roger Ndong Atome

    2018-03-01

    Full Text Available Gout is caused by a chronic hyperuricemia whose complications are not currently well evaluated in Africa. The aim of this study was to determine the prevalence and risk factors of hyperuricemia and gout in 85 patients recruited. A total of 26 cases of hyperuricemia, i.e., 30.6% of the study population, with 12 cases of gout and seven cases of gouty access. In this population, hyperuricemia was proportional to age (p-value < 10−4, OR = 2.6, but it was more prevalent in men, 23.5% versus 7.1% for women (p-value = 0.0047. In addition, none of these women showed signs of a gouty affection. Consumption of alcohol (OR = 13 and nucleoprotein-rich foods, obesity (BMI 30 kg/m2; OR = 6, family history of gout (OR = 6.8, as well as diseases such as high blood pressure (associated with taking diuretics; OR = 1.7, renal insufficiency (OR = 4.4 and diabetes (p < 0.049 were the main factors of the diseases associated with gout and hyperuricemia in this population. The biochemical role of these factors may increase and/or decrease the processes of synthesis and/or elimination of uric acid by acting on metabolites involved in the regulation of urate production.

  7. Hyper-Uricemia and Gouty Access in the Adult Population of the Southeast of Gabon: Biochemical Aspects.

    Science.gov (United States)

    Ndong Atome, Guy Roger; Ngoua Meye Misso, Rick-Leonid; Sima Obiang, Cédric; Onanga, Richard; Nkogue Mba, Dieudonné

    2018-03-08

    Gout is caused by a chronic hyperuricemia whose complications are not currently well evaluated in Africa. The aim of this study was to determine the prevalence and risk factors of hyperuricemia and gout in 85 patients recruited. A total of 26 cases of hyperuricemia, i.e., 30.6% of the study population, with 12 cases of gout and seven cases of gouty access. In this population, hyperuricemia was proportional to age ( p -value < 10 -4, OR = 2.6), but it was more prevalent in men, 23.5% versus 7.1% for women ( p -value = 0.0047). In addition, none of these women showed signs of a gouty affection. Consumption of alcohol (OR = 13) and nucleoprotein-rich foods, obesity (BMI 30 kg/m²; OR = 6), family history of gout (OR = 6.8), as well as diseases such as high blood pressure (associated with taking diuretics; OR = 1.7), renal insufficiency (OR = 4.4) and diabetes ( p < 0.049) were the main factors of the diseases associated with gout and hyperuricemia in this population. The biochemical role of these factors may increase and/or decrease the processes of synthesis and/or elimination of uric acid by acting on metabolites involved in the regulation of urate production.

  8. A new bio-inspired, population-level approach to the socioeconomic evolution of dynamic spectrum access services

    Science.gov (United States)

    Horvath, Denis; Gazda, Juraj; Brutovsky, Branislav

    Evolutionary species and quasispecies models provide the universal and flexible basis for a large-scale description of the dynamics of evolutionary systems, which can be built conceived as a constraint satisfaction dynamics. It represents a general framework to design and study many novel, technologically contemporary models and their variants. Here, we apply the classical quasispecies concept to model the emerging dynamic spectrum access (DSA) markets. The theory describes the mechanisms of mimetic transfer, competitive interactions between socioeconomic strata of the end-users, their perception of the utility and inter-operator switching in the variable technological environments of the operators offering the wireless spectrum services. The algorithmization and numerical modeling demonstrate the long-term evolutionary socioeconomic changes which reflect the end-user preferences and results of the majorization of their irrational decisions in the same manner as the prevailing tendencies which are embodied in the efficient market hypothesis.

  9. Is the Brazilian pharmaceutical policy ensuring population access to essential medicines?

    Directory of Open Access Journals (Sweden)

    Bertoldi Andréa

    2012-03-01

    Full Text Available Abstract Background To evaluate medicine prices, availability and affordability in Brazil, considering the differences across three types of medicines (originator brands, generics and similar medicines and different types of facilities (private pharmacies, public sector pharmacies and “popular pharmacies”. Methods Data on prices and availability of 50 medicines were collected in 56 pharmacies across six cities in Southern Brazil using the World Health Organization / Health Action International methodology. Median prices obtained were divided by international reference prices to derive the median price ratio (MPR. Results In the private sector, prices were 8.6 MPR for similar medicines, 11.3 MRP for generics and 18.7 MRP for originator brands, respectively. Mean availability was 65%, 74% and 48% for originator brands, generics and similar medicines, respectively. In the public sector, mean availability of similar medicines was 2–7 times higher than that of generics. Mean overall availability in the public sector ranged from 68.8% to 81.7%. In “popular pharmacies”, mean availability was greater than 90% in all cities. Conclusions Availability of medicines in the public sector does not meet the challenge of supplying essential medicines to the entire population, as stated in the Brazilian constitution. This has unavoidable repercussions for affordability, particularly amongst the lower socio-economic strata.

  10. Delays in accessing electroconvulsive therapy: a comparison between two urban and two rural populations in Australia.

    Science.gov (United States)

    Johnston, Natalie E

    2015-10-01

    A comparison of the timing, rates and characteristics of electroconvulsive therapy use between urban and rural populations. The medical records of patients who received an acute course of electroconvulsive therapy at two rural and two urban psychiatric hospitals in New South Wales (NSW), Australia, in 2010 were reviewed retrospectively. Main outcome measures were the time from symptom onset, diagnosis and admission to commencing electroconvulsive therapy. Rates of use of electroconvulsive therapy were also compared between rural and urban hospitals using NSW statewide data. There was a significant delay in the time it took for rural patients to receive electroconvulsive therapy compared with urban patients when measured both from the time of symptom onset and from when they received a diagnosis. There were corresponding delays in the time taken for rural patients to be admitted to hospital compared with urban patients. There was no difference in the time it took to commence electroconvulsive therapy once a patient was admitted to hospital. NSW statewide urban-rural comparisons showed rates of electroconvulsive therapy treatment were significantly higher in urban hospitals. Patients in rural areas receive electroconvulsive therapy later in their acute illness due to delays in being admitted to hospital. The rate of use of electroconvulsive therapy also differs geographically. © The Royal Australian and New Zealand College of Psychiatrists 2015.

  11. Persistent digital divide in access to and use of the Internet as a resource for health information: Results from a California population-based study.

    Science.gov (United States)

    Nguyen, Amy; Mosadeghi, Sasan; Almario, Christopher V

    2017-07-01

    Access to the Internet has grown dramatically over the past two decades. Using data from a population-based survey, we aimed to determine the prevalence and predictors of (i) access to the Internet, and (ii) use of the Internet to search for health information. We analyzed data from the 2011-12 California Health Interview Survey (CHIS) and included all individuals 18 years of age and older. Our outcomes were (i) prior use of the Internet, and (ii) use of the Internet to find health or medical information within the past year. We performed survey-weighted logistic regression models on our outcomes to adjust for potentially confounding demographic and socioeconomic factors. Our study included an unweighted and survey-weighted sample of 42,935 and 27,796,484 individuals, respectively. We found that 81.5% of the weighted sample reported having previously used the Internet. Among Internet users, 64.5% stated that they used the Internet within the past year to find health or medical information. Racial/ethnic minorities, older individuals, and those who lived in lower income households and rural areas were less likely to have access to and use the Internet to search for health information. Conversely, English-proficiency and increasing levels of education were positively associated with online health information-seeking. We found that most Californians have access to and use the Internet to search for health information, but still noted a persistent digital divide. Interventions to narrow the divide are needed, otherwise this may lead to a continued widening of existing healthcare disparities. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. The Statistical Modeling of the Trends Concerning the Romanian Population

    Directory of Open Access Journals (Sweden)

    Gabriela OPAIT

    2014-11-01

    Full Text Available This paper reflects the statistical modeling concerning the resident population in Romania, respectively the total of the romanian population, through by means of the „Least Squares Method”. Any country it develops by increasing of the population, respectively of the workforce, which is a factor of influence for the growth of the Gross Domestic Product (G.D.P.. The „Least Squares Method” represents a statistical technique for to determine the trend line of the best fit concerning a model.

  13. PBPK and population modelling to interpret urine cadmium concentrations of the French population

    Energy Technology Data Exchange (ETDEWEB)

    Béchaux, Camille, E-mail: Camille.bechaux@anses.fr [ANSES, French Agency for Food, Environmental and Occupational Health Safety, 27-31 Avenue du Général Leclerc, 94701 Maisons-Alfort (France); Bodin, Laurent [ANSES, French Agency for Food, Environmental and Occupational Health Safety, 27-31 Avenue du Général Leclerc, 94701 Maisons-Alfort (France); Clémençon, Stéphan [Telecom ParisTech, 46 rue Barrault, 75634 Paris Cedex 13 (France); Crépet, Amélie [ANSES, French Agency for Food, Environmental and Occupational Health Safety, 27-31 Avenue du Général Leclerc, 94701 Maisons-Alfort (France)

    2014-09-15

    As cadmium accumulates mainly in kidney, urinary concentrations are considered as relevant data to assess the risk related to cadmium. The French Nutrition and Health Survey (ENNS) recorded the concentration of cadmium in the urine of the French population. However, as with all biomonitoring data, it needs to be linked to external exposure for it to be interpreted in term of sources of exposure and for risk management purposes. The objective of this work is thus to interpret the cadmium biomonitoring data of the French population in terms of dietary and cigarette smoke exposures. Dietary and smoking habits recorded in the ENNS study were combined with contamination levels in food and cigarettes to assess individual exposures. A PBPK model was used in a Bayesian population model to link this external exposure with the measured urinary concentrations. In this model, the level of the past exposure was corrected thanks to a scaling function which account for a trend in the French dietary exposure. It resulted in a modelling which was able to explain the current urinary concentrations measured in the French population through current and past exposure levels. Risk related to cadmium exposure in the general French population was then assessed from external and internal critical values corresponding to kidney effects. The model was also applied to predict the possible urinary concentrations of the French population in 2030 assuming there will be no more changes in the exposures levels. This scenario leads to significantly lower concentrations and consequently lower related risk. - Highlights: • Interpretation of urine cadmium concentrations in France • PBPK and Bayesian population modelling of cadmium exposure • Assessment of the historic time-trend of the cadmium exposure in France • Risk assessment from current and future external and internal exposure.

  14. PBPK and population modelling to interpret urine cadmium concentrations of the French population

    International Nuclear Information System (INIS)

    Béchaux, Camille; Bodin, Laurent; Clémençon, Stéphan; Crépet, Amélie

    2014-01-01

    As cadmium accumulates mainly in kidney, urinary concentrations are considered as relevant data to assess the risk related to cadmium. The French Nutrition and Health Survey (ENNS) recorded the concentration of cadmium in the urine of the French population. However, as with all biomonitoring data, it needs to be linked to external exposure for it to be interpreted in term of sources of exposure and for risk management purposes. The objective of this work is thus to interpret the cadmium biomonitoring data of the French population in terms of dietary and cigarette smoke exposures. Dietary and smoking habits recorded in the ENNS study were combined with contamination levels in food and cigarettes to assess individual exposures. A PBPK model was used in a Bayesian population model to link this external exposure with the measured urinary concentrations. In this model, the level of the past exposure was corrected thanks to a scaling function which account for a trend in the French dietary exposure. It resulted in a modelling which was able to explain the current urinary concentrations measured in the French population through current and past exposure levels. Risk related to cadmium exposure in the general French population was then assessed from external and internal critical values corresponding to kidney effects. The model was also applied to predict the possible urinary concentrations of the French population in 2030 assuming there will be no more changes in the exposures levels. This scenario leads to significantly lower concentrations and consequently lower related risk. - Highlights: • Interpretation of urine cadmium concentrations in France • PBPK and Bayesian population modelling of cadmium exposure • Assessment of the historic time-trend of the cadmium exposure in France • Risk assessment from current and future external and internal exposure

  15. MODEL OF FEES CALCULATION FOR ACCESS TO TRACK INFRASTRUCTURE FACILITIES

    Directory of Open Access Journals (Sweden)

    M. I. Mishchenko

    2014-12-01

    Full Text Available Purpose. The purpose of the article is to develop a one- and two-element model of the fees calculation for the use of track infrastructure of Ukrainian railway transport. Methodology. On the basis of this one can consider that when planning the planned preventive track repair works and the amount of depreciation charges the guiding criterion is not the amount of progress it is the operating life of the track infrastructure facilities. The cost of PPTRW is determined on the basis of the following: the classification track repairs; typical technological processes for track repairs; technology based time standards for PPTRW; costs for the work of people, performing the PPTRW, their hourly wage rates according to the Order 98-Ts; the operating cost of machinery; regulated list; norms of expenditures and costs of materials and products (they have the largest share of the costs for repairs; railway rates; average distances for transportation of materials used during repair; standards of general production expenses and the administrative costs. Findings. The models offered in article allow executing the objective account of expenses in travelling facilities for the purpose of calculation of the proved size of indemnification and necessary size of profit, the sufficient enterprises for effective activity of a travelling infrastructure. Originality. The methodological bases of determination the fees (payments for the use of track infrastructure on one- and two-element base taking into account the experience of railways in the EC countries and the current transport legislation were grounded. Practical value. The article proposes the one- and two-element models of calculating the fees (payments for the TIF use, accounting the applicable requirements of European transport legislation, which provides the expense compensation and income formation, sufficient for economic incentives of the efficient operation of the TIE of Ukrainian railway transport.

  16. Accessibility of the pre-big-bang models to LIGO

    International Nuclear Information System (INIS)

    Mandic, Vuk; Buonanno, Alessandra

    2006-01-01

    The recent search for a stochastic background of gravitational waves with LIGO interferometers has produced a new upper bound on the amplitude of this background in the 100 Hz region. We investigate the implications of the current and future LIGO results on pre-big-bang models of the early Universe, determining the exclusion regions in the parameter space of the minimal pre-big-bang scenario. Although the current LIGO reach is still weaker than the indirect bound from big bang nucleosynthesis, future runs by LIGO, in the coming year, and by Advanced LIGO (∼2009) should further constrain the parameter space, and in some parts surpass the Big Bang nucleosynthesis bound. It will be more difficult to constrain the parameter space in nonminimal pre-big bang models, which are characterized by multiple cosmological phases in the yet not well understood stringy phase, and where the higher-order curvature and/or quantum-loop corrections in the string effective action should be included

  17. From the Margins to the Spotlight: Diverse Deaf and Hard of Hearing Student Populations and Standardized Assessment Accessibility.

    Science.gov (United States)

    Cawthon, Stephanie

    2015-01-01

    Designing assessments and tests is one of the more challenging aspects of creating an accessible learning environment for students who are deaf or hard of hearing (DHH), particularly for deaf students with a disability (DWD). Standardized assessments are a key mechanism by which the educational system in the United States measures student progress, teacher effectiveness, and the impact of school reform. The diversity of student characteristics within DHH and DWD populations is only now becoming visible in the research literature relating to standardized assessments and their use in large-scale accountability reforms. The purpose of this article is to explore the theoretical frameworks surrounding assessment policy and practice, current research related to standardized assessment and students who are DHH and DWD, and potential implications for practice within both the assessment and instruction contexts.

  18. An investigation of an open-access model for scaling up methadone maintenance treatment.

    Science.gov (United States)

    Madden, Lynn M; Farnum, Scott O; Eggert, Kathryn F; Quanbeck, Andrew R; Freeman, Robert M; Ball, Samuel A; Schottenfeld, Richard S; Shi, Julia M; Savage, Mary Ellen; Barry, Declan T

    2018-02-17

    To examine retrospectively patient and programmatic outcomes following the development and implementation of an 'open-access' model in which prospective patients were enrolled rapidly in methadone maintenance treatment, irrespective of ability to pay, and provided real-time access to multiple voluntary treatment options. Medical and administrative records were abstracted to compare data for 1 year before and 9 years after initiating the implementation of an open-access treatment model in May 2007. Methadone maintenance treatment center in Connecticut, USA. Individuals with opioid use disorder entering treatment between July 2006 and June 2015. In June 2015, 64% (n = 2594) of the sample were men and 80% (n = 3133) reported that they were white. The Network for the Improvement of Addiction Treatment-informed open-access treatment model uses process improvement strategies to improve treatment access and capacity. Census, waiting time, retention, non-medical opioid use, patient mortality and financial sustainability (net income and state-block grants as proportions of revenue). In the 9 years following the initial implementation of the open-access model, patient census increased by 183% from 1431 to 4051, and average waiting-time days decreased from 21 to 0.3 (same day) without apparent deleterious effects on rates of retention, non-medical opioid use or mortality. Between fiscal years (FY) 06 and FY 15, net operating margin rose from 2 to 10%, while state-block grant revenues declined 14% and the proportion of total revenue from state-block grant revenue decreased from 49 to 24%. An open-access model for rapid enrolment of people with opioid use disorder in methadone treatment appears to improve treatment access, capacity, and financial sustainability without evidence of deleterious effects on treatment outcomes. © 2018 Society for the Study of Addiction.

  19. Open Access Publishing from the Legal Point of View. Why Freedom of Information Rules and Other Legal Principles Matter. Towards A New Fair Open Access Model.

    Directory of Open Access Journals (Sweden)

    Jiří Kolman

    2013-10-01

    Full Text Available This article focuses on aspects that, as far as we know, have never been discussed in previous debates dealing with open access. The EU and national competition legal rules ensuring fair competition are a rather neglected aspect of open access. Another crucial topic is the unfairness of the current publication system. Why should commercial publishers be paid by publicly supported research such as EU or national research programmes? In the article a new publication model is suggested. The proposed model is trying to keep high research standards, to be fair to researchers and the public and to take into account the actual costs of the new open access model.

  20. Developing population models with data from marked individuals

    Science.gov (United States)

    Hae Yeong Ryu,; Kevin T. Shoemaker,; Eva Kneip,; Anna Pidgeon,; Patricia Heglund,; Brooke Bateman,; Thogmartin, Wayne E.; Reşit Akçakaya,

    2016-01-01

    Population viability analysis (PVA) is a powerful tool for biodiversity assessments, but its use has been limited because of the requirements for fully specified population models such as demographic structure, density-dependence, environmental stochasticity, and specification of uncertainties. Developing a fully specified population model from commonly available data sources – notably, mark–recapture studies – remains complicated due to lack of practical methods for estimating fecundity, true survival (as opposed to apparent survival), natural temporal variability in both survival and fecundity, density-dependence in the demographic parameters, and uncertainty in model parameters. We present a general method that estimates all the key parameters required to specify a stochastic, matrix-based population model, constructed using a long-term mark–recapture dataset. Unlike standard mark–recapture analyses, our approach provides estimates of true survival rates and fecundities, their respective natural temporal variabilities, and density-dependence functions, making it possible to construct a population model for long-term projection of population dynamics. Furthermore, our method includes a formal quantification of parameter uncertainty for global (multivariate) sensitivity analysis. We apply this approach to 9 bird species and demonstrate the feasibility of using data from the Monitoring Avian Productivity and Survivorship (MAPS) program. Bias-correction factors for raw estimates of survival and fecundity derived from mark–recapture data (apparent survival and juvenile:adult ratio, respectively) were non-negligible, and corrected parameters were generally more biologically reasonable than their uncorrected counterparts. Our method allows the development of fully specified stochastic population models using a single, widely available data source, substantially reducing the barriers that have until now limited the widespread application of PVA. This method

  1. "Population and poverty: major barriers to food accessibility" -- a panel discussion on civil society and people's participation.

    Science.gov (United States)

    1996-01-01

    This paper summarizes conference statements on poverty and food policies that were made by parliamentary members from Malaysia, the Philippines, and India. These presentations were made after the main panel discussion on barriers to food accessibility. In Malaysia the government adopted a National Agricultural Policy in 1984. This policy encouraged increased productivity, effective use of resources, agricultural credit and incentives, and integrated pest management. Strong support was given to the food processing industry. Poverty was the main reason for food inaccessibility. Through government efforts, poverty was reduced from 16.5% in 1990 to 8.9% in 1995. The Filipino member reported that government efforts had focused on national campaigns to combat hunger and to encourage community participation. The government was forced to implement a national Plan of Action for Food Security due to increased population, environmental degradation, closing land frontiers, and the global economy. The Plan encouraged increases in productivity, price and supply stabilization, maintenance of stocks, and rice subsidies for the poor. Gender concerns were being incorporated into development programs. The Indian member linked food insecurity to world resource problems. He stated that food problems included imbalances between supply and demand, but more importantly inequalities in access to food and differences in nutritional content of food. Populations in developing countries spent a larger proportion of income on food of lesser quality and variety that contributed to nutritional deficiencies, particularly among women and children. Food insecurity was part of the cycle of poverty, hunger, low productivity, and high mortality. Poverty was the primary cause and a major consequence of hunger and chronic food insecurity. Although India increased food productivity, food insecurity remained. Multidisciplinary approaches are needed.

  2. Access Control Mechanism for IoT Environments Based on Modelling Communication Procedures as Resources.

    Science.gov (United States)

    Cruz-Piris, Luis; Rivera, Diego; Marsa-Maestre, Ivan; de la Hoz, Enrique; Velasco, Juan R

    2018-03-20

    Internet growth has generated new types of services where the use of sensors and actuators is especially remarkable. These services compose what is known as the Internet of Things (IoT). One of the biggest current challenges is obtaining a safe and easy access control scheme for the data managed in these services. We propose integrating IoT devices in an access control system designed for Web-based services by modelling certain IoT communication elements as resources. This would allow us to obtain a unified access control scheme between heterogeneous devices (IoT devices, Internet-based services, etc.). To achieve this, we have analysed the most relevant communication protocols for these kinds of environments and then we have proposed a methodology which allows the modelling of communication actions as resources. Then, we can protect these resources using access control mechanisms. The validation of our proposal has been carried out by selecting a communication protocol based on message exchange, specifically Message Queuing Telemetry Transport (MQTT). As an access control scheme, we have selected User-Managed Access (UMA), an existing Open Authorization (OAuth) 2.0 profile originally developed for the protection of Internet services. We have performed tests focused on validating the proposed solution in terms of the correctness of the access control system. Finally, we have evaluated the energy consumption overhead when using our proposal.

  3. Access Control Mechanism for IoT Environments Based on Modelling Communication Procedures as Resources

    Directory of Open Access Journals (Sweden)

    Luis Cruz-Piris

    2018-03-01

    Full Text Available Internet growth has generated new types of services where the use of sensors and actuators is especially remarkable. These services compose what is known as the Internet of Things (IoT. One of the biggest current challenges is obtaining a safe and easy access control scheme for the data managed in these services. We propose integrating IoT devices in an access control system designed for Web-based services by modelling certain IoT communication elements as resources. This would allow us to obtain a unified access control scheme between heterogeneous devices (IoT devices, Internet-based services, etc.. To achieve this, we have analysed the most relevant communication protocols for these kinds of environments and then we have proposed a methodology which allows the modelling of communication actions as resources. Then, we can protect these resources using access control mechanisms. The validation of our proposal has been carried out by selecting a communication protocol based on message exchange, specifically Message Queuing Telemetry Transport (MQTT. As an access control scheme, we have selected User-Managed Access (UMA, an existing Open Authorization (OAuth 2.0 profile originally developed for the protection of Internet services. We have performed tests focused on validating the proposed solution in terms of the correctness of the access control system. Finally, we have evaluated the energy consumption overhead when using our proposal.

  4. Access, excess, and ethics--towards a sustainable distribution model for antibiotics.

    Science.gov (United States)

    Heyman, Gabriel; Cars, Otto; Bejarano, Maria-Teresa; Peterson, Stefan

    2014-05-01

    The increasing antibiotic resistance is a global threat to health care as we know it. Yet there is no model of distribution ready for a new antibiotic that balances access against excessive or inappropriate use in rural settings in low- and middle-income countries (LMICs) where the burden of communicable diseases is high and access to quality health care is low. Departing from a hypothetical scenario of rising antibiotic resistance among pneumococci, 11 stakeholders in the health systems of various LMICs were interviewed one-on-one to give their view on how a new effective antibiotic should be distributed to balance access against the risk of inappropriate use. Transcripts were subjected to qualitative 'framework' analysis. The analysis resulted in four main themes: Barriers to rational access to antibiotics; balancing access and excess; learning from other communicable diseases; and a system-wide intervention. The tension between access to antibiotics and rational use stems from shortcomings found in the health systems of LMICs. Constructing a sustainable yet accessible model of antibiotic distribution for LMICs is a task of health system-wide proportions, which is why we strongly suggest using systems thinking in future research on this issue.

  5. Access Control Mechanism for IoT Environments Based on Modelling Communication Procedures as Resources

    Science.gov (United States)

    2018-01-01

    Internet growth has generated new types of services where the use of sensors and actuators is especially remarkable. These services compose what is known as the Internet of Things (IoT). One of the biggest current challenges is obtaining a safe and easy access control scheme for the data managed in these services. We propose integrating IoT devices in an access control system designed for Web-based services by modelling certain IoT communication elements as resources. This would allow us to obtain a unified access control scheme between heterogeneous devices (IoT devices, Internet-based services, etc.). To achieve this, we have analysed the most relevant communication protocols for these kinds of environments and then we have proposed a methodology which allows the modelling of communication actions as resources. Then, we can protect these resources using access control mechanisms. The validation of our proposal has been carried out by selecting a communication protocol based on message exchange, specifically Message Queuing Telemetry Transport (MQTT). As an access control scheme, we have selected User-Managed Access (UMA), an existing Open Authorization (OAuth) 2.0 profile originally developed for the protection of Internet services. We have performed tests focused on validating the proposed solution in terms of the correctness of the access control system. Finally, we have evaluated the energy consumption overhead when using our proposal. PMID:29558406

  6. Spatiotemporal access model based on reputation for the sensing layer of the IoT.

    Science.gov (United States)

    Guo, Yunchuan; Yin, Lihua; Li, Chao; Qian, Junyan

    2014-01-01

    Access control is a key technology in providing security in the Internet of Things (IoT). The mainstream security approach proposed for the sensing layer of the IoT concentrates only on authentication while ignoring the more general models. Unreliable communications and resource constraints make the traditional access control techniques barely meet the requirements of the sensing layer of the IoT. In this paper, we propose a model that combines space and time with reputation to control access to the information within the sensing layer of the IoT. This model is called spatiotemporal access control based on reputation (STRAC). STRAC uses a lattice-based approach to decrease the size of policy bases. To solve the problem caused by unreliable communications, we propose both nondeterministic authorizations and stochastic authorizations. To more precisely manage the reputation of nodes, we propose two new mechanisms to update the reputation of nodes. These new approaches are the authority-based update mechanism (AUM) and the election-based update mechanism (EUM). We show how the model checker UPPAAL can be used to analyze the spatiotemporal access control model of an application. Finally, we also implement a prototype system to demonstrate the efficiency of our model.

  7. Spatiotemporal Access Model Based on Reputation for the Sensing Layer of the IoT

    Directory of Open Access Journals (Sweden)

    Yunchuan Guo

    2014-01-01

    Full Text Available Access control is a key technology in providing security in the Internet of Things (IoT. The mainstream security approach proposed for the sensing layer of the IoT concentrates only on authentication while ignoring the more general models. Unreliable communications and resource constraints make the traditional access control techniques barely meet the requirements of the sensing layer of the IoT. In this paper, we propose a model that combines space and time with reputation to control access to the information within the sensing layer of the IoT. This model is called spatiotemporal access control based on reputation (STRAC. STRAC uses a lattice-based approach to decrease the size of policy bases. To solve the problem caused by unreliable communications, we propose both nondeterministic authorizations and stochastic authorizations. To more precisely manage the reputation of nodes, we propose two new mechanisms to update the reputation of nodes. These new approaches are the authority-based update mechanism (AUM and the election-based update mechanism (EUM. We show how the model checker UPPAAL can be used to analyze the spatiotemporal access control model of an application. Finally, we also implement a prototype system to demonstrate the efficiency of our model.

  8. Development and Testing of a Conceptual Model Regarding Men's Access to Health Care.

    Science.gov (United States)

    Leone, James E; Rovito, Michael J; Mullin, Elizabeth M; Mohammed, Shan D; Lee, Christina S

    2017-03-01

    Epidemiologic data suggest men often experience excessive morbidity and early mortality, possibly compromising family and community health over the lifespan. Moreover, the negative financial/economic consequences affected by poor male health outcomes also has been of great concern in the United States and abroad. Early and consistent access to preventative health care may improve health outcomes; however, men are far less likely to access these services. The purpose of this study was to understand what factors preclude men from accessing health care. We surveyed 485 participants using a 58-item online survey built from a conceptual model previously developed by the researchers using hegemonic masculinity theory, the theory of normative contentment, and the health belief model. For men, three items significantly ( ps masculine ideals may play a primary role in how men access preventative health care. Future programming targeting males should consider barriers and plan programs that are gender-sensitive in addition to being gender-specific. Clinical implications are discussed.

  9. Hierarchy Bayesian model based services awareness of high-speed optical access networks

    Science.gov (United States)

    Bai, Hui-feng

    2018-03-01

    As the speed of optical access networks soars with ever increasing multiple services, the service-supporting ability of optical access networks suffers greatly from the shortage of service awareness. Aiming to solve this problem, a hierarchy Bayesian model based services awareness mechanism is proposed for high-speed optical access networks. This approach builds a so-called hierarchy Bayesian model, according to the structure of typical optical access networks. Moreover, the proposed scheme is able to conduct simple services awareness operation in each optical network unit (ONU) and to perform complex services awareness from the whole view of system in optical line terminal (OLT). Simulation results show that the proposed scheme is able to achieve better quality of services (QoS), in terms of packet loss rate and time delay.

  10. Testing the priority-of-access model in a seasonally breeding primate species

    OpenAIRE

    Dubuc, Constance; Muniz, Laura; Heistermann, Michael; Engelhardt, Antje; Widdig, Anja

    2011-01-01

    In mammals, when females are clumped in space, male access to receptive females is usually determined by a dominance hierarchy based on fighting ability. In polygynandrous primates, as opposed to most mammalian species, the strength of the relationship between male social status and reproductive success varies greatly. It has been proposed that the degree to which paternity is determined by male rank decreases with increasing female reproductive synchrony. The priority-of-access model (PoA) p...

  11. Modeling X-linked ancestral origins in multiparental populations

    NARCIS (Netherlands)

    Zheng, Chaozhi

    2015-01-01

    The models for the mosaic structure of an individual's genome from multiparental populations have been developed primarily for autosomes, whereas X chromosomes receive very little attention. In this paper, we extend our previous approach to model ancestral origin processes along two X chromosomes

  12. A Two Population Model for the Stock Market Problem

    Science.gov (United States)

    Skiadas, Christos H.

    The development of the last year disaster in the Stock Markets all over the world gave rise to reconsidering the previous models used. It is clear that, even in an organized international or national context, large fluctuations and sudden losses may occur. This paper explores a two populations' model. The populations are conflicting into the same environment (a Stock Market) by following the main rules present, that is mutual interaction between adopters, potential adopters, word-of-mouth communication and of course by taking into consideration the innovation diffusion process. The proposed model has special futures expressed by third order terms providing characteristic stationary points.

  13. Nonlinear Stochastic Modelling of Antimicrobial resistance in Bacterial Populations

    DEFF Research Database (Denmark)

    Philipsen, Kirsten Riber

    -mutator population. The growth rates of the two populations were initially compared by a maximum likelihood approach and the growth rates were found to be equal. Thereafter a model for the competing growth was developed. The models showthat mutatorswill obtain a higher fitness by adapting faster to an environment...... an important role for the evolution of resistance. When growing under stressed conditions, such as in the presence of antibiotics, mutators are considered to have an advantages in comparison to non-mutators. This has been supported by a mathematical model for competing growth between a mutator and a non...

  14. Composite spectral functions for solving Volterra's population model

    International Nuclear Information System (INIS)

    Ramezani, M.; Razzaghi, M.; Dehghan, M.

    2007-01-01

    An approximate method for solving Volterra's population model for population growth of a species in a closed system is proposed. Volterra's model is a nonlinear integro-differential equation, where the integral term represents the effect of toxin. The approach is based upon composite spectral functions approximations. The properties of composite spectral functions consisting of few terms of orthogonal functions are presented and are utilized to reduce the solution of the Volterra's model to the solution of a system of algebraic equations. The method is easy to implement and yields very accurate result

  15. Modeling structured population dynamics using data from unmarked individuals

    Science.gov (United States)

    Grant, Evan H. Campbell; Zipkin, Elise; Thorson, James T.; See, Kevin; Lynch, Heather J.; Kanno, Yoichiro; Chandler, Richard; Letcher, Benjamin H.; Royle, J. Andrew

    2014-01-01

    The study of population dynamics requires unbiased, precise estimates of abundance and vital rates that account for the demographic structure inherent in all wildlife and plant populations. Traditionally, these estimates have only been available through approaches that rely on intensive mark–recapture data. We extended recently developed N-mixture models to demonstrate how demographic parameters and abundance can be estimated for structured populations using only stage-structured count data. Our modeling framework can be used to make reliable inferences on abundance as well as recruitment, immigration, stage-specific survival, and detection rates during sampling. We present a range of simulations to illustrate the data requirements, including the number of years and locations necessary for accurate and precise parameter estimates. We apply our modeling framework to a population of northern dusky salamanders (Desmognathus fuscus) in the mid-Atlantic region (USA) and find that the population is unexpectedly declining. Our approach represents a valuable advance in the estimation of population dynamics using multistate data from unmarked individuals and should additionally be useful in the development of integrated models that combine data from intensive (e.g., mark–recapture) and extensive (e.g., counts) data sources.

  16. Do new and traditional models of primary care differ with regard to access?: Canadian QUALICOPC study.

    Science.gov (United States)

    Miedema, Baukje; Easley, Julie; Thompson, Ashley E; Boivin, Antoine; Aubrey-Bassler, Kris; Katz, Alan; Hogg, William E; Breton, Mylaine; Francoeur, Danièle; Wong, Sabrina T; Wodchis, Walter P

    2016-01-01

    To examine access to primary care in new and traditional models using 2 dimensions of the concept of patient-centred access. An international survey examining the quality and costs of primary health care (the QUALICOPC study) was conducted in 2013 in Canada. This study adopted a descriptive cross-sectional survey method using data from practices across Canada. Each participating practice filled out the Family Physician Survey and the Practice Survey, and patients in each participating practice were asked to complete the Patient Experiences Survey. All 10 Canadian provinces. A total of 759 practices and 7172 patients. Independent t tests were conducted to examine differences between new and traditional models of care in terms of availability and accommodation, and affordability of care. Of the 759 practices, 407 were identified as having new models of care and 352 were identified as traditional. New models of care were distinct with respect to payment structure, opening hours, and having an interdisciplinary work force. Most participating practices were from large cities or suburban areas. There were few differences between new and traditional models of care regarding accessibility and accommodation in primary care. Patients under new models of care reported easier access to other physicians in the same practice, while patients from traditional models reported seeing their regular family physicians more frequently. There was no difference between the new and traditional models of care with regard to affordability of primary care. Patients attending clinics with new models of care reported that their physicians were more involved with them as a whole person than patients attending clinics based on traditional models did. Primary care access issues do not differ strongly between traditional and new models of care; however, patients in the new models of care believed that their physicians were more involved with them as people.

  17. Feasibility Assessment of a Fine-Grained Access Control Model on Resource Constrained Sensors.

    Science.gov (United States)

    Uriarte Itzazelaia, Mikel; Astorga, Jasone; Jacob, Eduardo; Huarte, Maider; Romaña, Pedro

    2018-02-13

    Upcoming smart scenarios enabled by the Internet of Things (IoT) envision smart objects that provide services that can adapt to user behavior or be managed to achieve greater productivity. In such environments, smart things are inexpensive and, therefore, constrained devices. However, they are also critical components because of the importance of the information that they provide. Given this, strong security is a requirement, but not all security mechanisms in general and access control models in particular are feasible. In this paper, we present the feasibility assessment of an access control model that utilizes a hybrid architecture and a policy language that provides dynamic fine-grained policy enforcement in the sensors, which requires an efficient message exchange protocol called Hidra. This experimental performance assessment includes a prototype implementation, a performance evaluation model, the measurements and related discussions, which demonstrate the feasibility and adequacy of the analyzed access control model.

  18. Multi-views storage model and access methods of conversation history in converged IP messaging system

    Science.gov (United States)

    Lu, Meilian; Yang, Dong; Zhou, Xing

    2013-03-01

    Based on the analysis of the requirements of conversation history storage in CPM (Converged IP Messaging) system, a Multi-views storage model and access methods of conversation history are proposed. The storage model separates logical views from physical storage and divides the storage into system managed region and user managed region. It simultaneously supports conversation view, system pre-defined view and user-defined view of storage. The rationality and feasibility of multi-view presentation, the physical storage model and access methods are validated through the implemented prototype. It proves that, this proposal has good scalability, which will help to optimize the physical data storage structure and improve storage performance.

  19. Modeling the video distribution link in the Next Generation Optical Access Networks

    DEFF Research Database (Denmark)

    Amaya, F.; Cárdenas, A.; Tafur Monroy, Idelfonso

    2011-01-01

    In this work we present a model for the design and optimization of the video distribution link in the next generation optical access network. We analyze the video distribution performance in a SCM-WDM link, including the noise, the distortion and the fiber optic nonlinearities. Additionally, we...... consider in the model the effect of distributed Raman amplification, used to extent the capacity and the reach of the optical link. In the model, we use the nonlinear Schrödinger equation with the purpose to obtain capacity limitations and design constrains of the next generation optical access networks....

  20. Modeling the video distribution link in the Next Generation Optical Access Networks

    International Nuclear Information System (INIS)

    Amaya, F; Cardenas, A; Tafur, I

    2011-01-01

    In this work we present a model for the design and optimization of the video distribution link in the next generation optical access network. We analyze the video distribution performance in a SCM-WDM link, including the noise, the distortion and the fiber optic nonlinearities. Additionally, we consider in the model the effect of distributed Raman amplification, used to extent the capacity and the reach of the optical link. In the model, we use the nonlinear Schroedinger equation with the purpose to obtain capacity limitations and design constrains of the next generation optical access networks.

  1. Mapping socio-environmentally vulnerable populations access and exposure to ecosystem services at the U.S.-Mexico borderlands

    Science.gov (United States)

    Norman, Laura M.; Villarreal, Miguel L.; Lara-Valencia, Francisco; Yuan, Yongping; Nie, Wenming; Wilson, Sylvia; Amaya, Gladys; Sleeter, Rachel

    2012-01-01

    Socio-environmental vulnerable populations are often unrepresented in land-use planning yet have great potential for loss when exposed to changes in ecosystem services. Administrative boundaries, cultural differences, and language barriers increase the disassociation between land-use management and marginalized populations living in the U.S.–Mexico borderlands. This paper describes the development of a Modified Socio-Environmental Vulnerability Index (M-SEVI), using determinants from binational census and neighborhood data that describe levels of education, access to resources, migratory status, housing, and number of dependents, to provide a simplified snapshot of the region's populace that can be used in binational planning efforts. We apply this index at the SCW, located on the border between Arizona, USA and Sonora, Mexico. For comparison, the Soil and Water Assessment Tool is concurrently applied to assess the provision of erosion- and flood control services over a 9-year period. We describe how this coupling of data can form the base for an ecosystem services assessment across political boundaries that can be used by land-use planners. Results reveal potential disparities in environmental risks and burdens throughout the binational watershed in residential districts surrounding and between urban centers. The M-SEVI can be used as an important first step in addressing environmental justice for binational decision-making.

  2. Predicting Graduation Rates at 4-Year Broad Access Institutions Using a Bayesian Modeling Approach

    Science.gov (United States)

    Crisp, Gloria; Doran, Erin; Salis Reyes, Nicole A.

    2018-01-01

    This study models graduation rates at 4-year broad access institutions (BAIs). We examine the student body, structural-demographic, and financial characteristics that best predict 6-year graduation rates across two time periods (2008-2009 and 2014-2015). A Bayesian model averaging approach is utilized to account for uncertainty in variable…

  3. Models for QoS-Aware Capacity Management in Cable Access Networks

    NARCIS (Netherlands)

    Attema, T.; van den Berg, Hans Leo; Kempker, P.C.; Worm, D.; van der Vliet-Hameeteman, C.

    In this article, mathematical models are presented that “map‿ measured or predicted network utilisations to user throughputs for given network configurations (segment capacity, subscription speeds etc.). They provide valuable insights into the user experience in cable access networks. The models,

  4. Video Modeling and Observational Learning to Teach Gaming Access to Students with ASD

    Science.gov (United States)

    Spriggs, Amy D.; Gast, David L.; Knight, Victoria F.

    2016-01-01

    The purpose of this study was to evaluate both video modeling and observational learning to teach age-appropriate recreation and leisure skills (i.e., accessing video games) to students with autism spectrum disorder. Effects of video modeling were evaluated via a multiple probe design across participants and criteria for mastery were based on…

  5. A stochastic population model to evaluate Moapa dace (Moapa coriacea) population growth under alternative management scenarios

    Science.gov (United States)

    Perry, Russell W.; Jones, Edward; Scoppettone, G. Gary

    2015-07-14

    The primary goal of this research project was to evaluate the response of Moapa dace (Moapa coriacea) to the potential effects of changes in the amount of available habitat due to human influences such as ground water pumping, barriers to movement, and extirpation of Moapa dace from the mainstem Muddy River. To understand how these factors affect Moapa dace populations and to provide a tool to guide recovery actions, we developed a stochastic model to simulate Moapa dace population dynamics. Specifically, we developed an individual based model (IBM) to incorporate the critical components that drive Moapa dace population dynamics. Our model is composed of several interlinked submodels that describe changes in Moapa dace habitat as translated into carrying capacity, the influence of carrying capacity on demographic rates of dace, and the consequent effect on equilibrium population sizes. The model is spatially explicit and represents the stream network as eight discrete stream segments. The model operates at a monthly time step to incorporate seasonally varying reproduction. Growth rates of individuals vary among stream segments, with growth rates increasing along a headwater to mainstem gradient. Movement and survival of individuals are driven by density-dependent relationships that are influenced by the carrying capacity of each stream segment.

  6. On reducibility and ergodicity of population projection matrix models

    DEFF Research Database (Denmark)

    Stott, Iain; Townley, Stuart; Carslake, David

    2010-01-01

    from all stages to all other stages) and therefore ergodic (whatever initial stage structure is used in the population projection, it will always exhibit the same stable asymptotic growth rate). 2. Evaluation of 652 PPM models for 171 species from the literature suggests that 24·7% of PPM models...... structure used in the population projection). In our sample of published PPMs, 15·6% are non-ergodic. 3. This presents a problem: reducible–ergodic models often defy biological rationale in their description of the life cycle but may or may not prove problematic for analysis as they often behave similarly...... of reducibility in published PPMs, with significant implications for the predictive power of such models in many cases. We suggest that as a general rule, reducibility of PPM models should be avoided. However, we provide a guide to the pertinent analysis of reducible matrix models, largely based upon whether...

  7. Phenobarbital in intensive care unit pediatric population: predictive performances of population pharmacokinetic model.

    Science.gov (United States)

    Marsot, Amélie; Michel, Fabrice; Chasseloup, Estelle; Paut, Olivier; Guilhaumou, Romain; Blin, Olivier

    2017-10-01

    An external evaluation of phenobarbital population pharmacokinetic model described by Marsot et al. was performed in pediatric intensive care unit. Model evaluation is an important issue for dose adjustment. This external evaluation should allow confirming the proposed dosage adaptation and extending these recommendations to the entire intensive care pediatric population. External evaluation of phenobarbital published population pharmacokinetic model of Marsot et al. was realized in a new retrospective dataset of 35 patients hospitalized in a pediatric intensive care unit. The published population pharmacokinetic model was implemented in nonmem 7.3. Predictive performance was assessed by quantifying bias and inaccuracy of model prediction. Normalized prediction distribution errors (NPDE) and visual predictive check (VPC) were also evaluated. A total of 35 infants were studied with a mean age of 33.5 weeks (range: 12 days-16 years) and a mean weight of 12.6 kg (range: 2.7-70.0 kg). The model predicted the observed phenobarbital concentrations with a reasonable bias and inaccuracy. The median prediction error was 3.03% (95% CI: -8.52 to 58.12%), and the median absolute prediction error was 26.20% (95% CI: 13.07-75.59%). No trends in NPDE and VPC were observed. The model previously proposed by Marsot et al. in neonates hospitalized in intensive care unit was externally validated for IV infusion administration. The model-based dosing regimen was extended in all pediatric intensive care unit to optimize treatment. Due to inter- and intravariability in pharmacokinetic model, this dosing regimen should be combined with therapeutic drug monitoring. © 2017 Société Française de Pharmacologie et de Thérapeutique.

  8. Periodic matrix models for seasonal dynamics of structured populations with application to a seabird population.

    Science.gov (United States)

    Cushing, J M; Henson, Shandelle M

    2018-02-03

    For structured populations with an annual breeding season, life-stage interactions and behavioral tactics may occur on a faster time scale than that of population dynamics. Motivated by recent field studies of the effect of rising sea surface temperature (SST) on within-breeding-season behaviors in colonial seabirds, we formulate and analyze a general class of discrete-time matrix models designed to account for changes in behavioral tactics within the breeding season and their dynamic consequences at the population level across breeding seasons. As a specific example, we focus on egg cannibalism and the daily reproductive synchrony observed in seabirds. Using the model, we investigate circumstances under which these life history tactics can be beneficial or non-beneficial at the population level in light of the expected continued rise in SST. Using bifurcation theoretic techniques, we study the nature of non-extinction, seasonal cycles as a function of environmental resource availability as they are created upon destabilization of the extinction state. Of particular interest are backward bifurcations in that they typically create strong Allee effects in population models which, in turn, lead to the benefit of possible (initial condition dependent) survival in adverse environments. We find that positive density effects (component Allee effects) due to increased adult survival from cannibalism and the propensity of females to synchronize daily egg laying can produce a strong Allee effect due to a backward bifurcation.

  9. Econometric model for age- and population-dependent radiation exposures

    International Nuclear Information System (INIS)

    Sandquist, G.M.; Slaughter, D.M.; Rogers, V.C.

    1991-01-01

    The economic impact associated with ionizing radiation exposures in a given human population depends on numerous factors including the individual's mean economic status as a function age, the age distribution of the population, the future life expectancy at each age, and the latency period for the occurrence of radiation-induced health effects. A simple mathematical model has been developed that provides an analytical methodology for estimating the societal econometrics associated with radiation effects are to be assessed and compared for economic evaluation

  10. On population size estimators in the Poisson mixture model.

    Science.gov (United States)

    Mao, Chang Xuan; Yang, Nan; Zhong, Jinhua

    2013-09-01

    Estimating population sizes via capture-recapture experiments has enormous applications. The Poisson mixture model can be adopted for those applications with a single list in which individuals appear one or more times. We compare several nonparametric estimators, including the Chao estimator, the Zelterman estimator, two jackknife estimators and the bootstrap estimator. The target parameter of the Chao estimator is a lower bound of the population size. Those of the other four estimators are not lower bounds, and they may produce lower confidence limits for the population size with poor coverage probabilities. A simulation study is reported and two examples are investigated. © 2013, The International Biometric Society.

  11. Modelling interactions of toxicants and density dependence in wildlife populations

    Science.gov (United States)

    Schipper, Aafke M.; Hendriks, Harrie W.M.; Kauffman, Matthew J.; Hendriks, A. Jan; Huijbregts, Mark A.J.

    2013-01-01

    1. A major challenge in the conservation of threatened and endangered species is to predict population decline and design appropriate recovery measures. However, anthropogenic impacts on wildlife populations are notoriously difficult to predict due to potentially nonlinear responses and interactions with natural ecological processes like density dependence. 2. Here, we incorporated both density dependence and anthropogenic stressors in a stage-based matrix population model and parameterized it for a density-dependent population of peregrine falcons Falco peregrinus exposed to two anthropogenic toxicants [dichlorodiphenyldichloroethylene (DDE) and polybrominated diphenyl ethers (PBDEs)]. Log-logistic exposure–response relationships were used to translate toxicant concentrations in peregrine falcon eggs to effects on fecundity. Density dependence was modelled as the probability of a nonbreeding bird acquiring a breeding territory as a function of the current number of breeders. 3. The equilibrium size of the population, as represented by the number of breeders, responded nonlinearly to increasing toxicant concentrations, showing a gradual decrease followed by a relatively steep decline. Initially, toxicant-induced reductions in population size were mitigated by an alleviation of the density limitation, that is, an increasing probability of territory acquisition. Once population density was no longer limiting, the toxicant impacts were no longer buffered by an increasing proportion of nonbreeders shifting to the breeding stage, resulting in a strong decrease in the equilibrium number of breeders. 4. Median critical exposure concentrations, that is, median toxicant concentrations in eggs corresponding with an equilibrium population size of zero, were 33 and 46 μg g−1 fresh weight for DDE and PBDEs, respectively. 5. Synthesis and applications. Our modelling results showed that particular life stages of a density-limited population may be relatively insensitive to

  12. Extinction threshold of a population in spatial and stochastic model

    OpenAIRE

    Soroka, Yevheniia; Rublyov, Bogdan

    2016-01-01

    In this study, spatial stochastic and logistic model (SSLM) describing dynamics of a population of a certain species was analysed. The behaviour of the extinction threshold as a function of model parameters was studied. More specifically, we studied how the critical values for the model parameters that separate the cases of extinction and persistence depend on the spatial scales of the competition and dispersal kernels. We compared the simulations and analytical results to examine if and how ...

  13. A statistical framework for the validation of a population exposure model based on personal exposure data

    Science.gov (United States)

    Rodriguez, Delphy; Valari, Myrto; Markakis, Konstantinos; Payan, Sébastien

    2016-04-01

    Currently, ambient pollutant concentrations at monitoring sites are routinely measured by local networks, such as AIRPARIF in Paris, France. Pollutant concentration fields are also simulated with regional-scale chemistry transport models such as CHIMERE (http://www.lmd.polytechnique.fr/chimere) under air-quality forecasting platforms (e.g. Prev'Air http://www.prevair.org) or research projects. These data may be combined with more or less sophisticated techniques to provide a fairly good representation of pollutant concentration spatial gradients over urban areas. Here we focus on human exposure to atmospheric contaminants. Based on census data on population dynamics and demographics, modeled outdoor concentrations and infiltration of outdoor air-pollution indoors we have developed a population exposure model for ozone and PM2.5. A critical challenge in the field of population exposure modeling is model validation since personal exposure data are expensive and therefore, rare. However, recent research has made low cost mobile sensors fairly common and therefore personal exposure data should become more and more accessible. In view of planned cohort field-campaigns where such data will be available over the Paris region, we propose in the present study a statistical framework that makes the comparison between modeled and measured exposures meaningful. Our ultimate goal is to evaluate the exposure model by comparing modeled exposures to monitor data. The scientific question we address here is how to downscale modeled data that are estimated on the county population scale at the individual scale which is appropriate to the available measurements. To assess this question we developed a Bayesian hierarchical framework that assimilates actual individual data into population statistics and updates the probability estimate.

  14. Nebular Continuum and Line Emission in Stellar Population Synthesis Models

    Energy Technology Data Exchange (ETDEWEB)

    Byler, Nell; Dalcanton, Julianne J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Conroy, Charlie; Johnson, Benjamin D., E-mail: ebyler@astro.washington.edu [Department of Astronomy, Harvard University, Cambridge, MA 02138 (United States)

    2017-05-01

    Accounting for nebular emission when modeling galaxy spectral energy distributions (SEDs) is important, as both line and continuum emissions can contribute significantly to the total observed flux. In this work, we present a new nebular emission model integrated within the Flexible Stellar Population Synthesis code that computes the line and continuum emission for complex stellar populations using the photoionization code Cloudy. The self-consistent coupling of the nebular emission to the matched ionizing spectrum produces emission line intensities that correctly scale with the stellar population as a function of age and metallicity. This more complete model of galaxy SEDs will improve estimates of global gas properties derived with diagnostic diagrams, star formation rates based on H α , and physical properties derived from broadband photometry. Our models agree well with results from other photoionization models and are able to reproduce observed emission from H ii regions and star-forming galaxies. Our models show improved agreement with the observed H ii regions in the Ne iii/O ii plane and show satisfactory agreement with He ii emission from z = 2 galaxies, when including rotating stellar models. Models including post-asymptotic giant branch stars are able to reproduce line ratios consistent with low-ionization emission regions. The models are integrated into current versions of FSPS and include self-consistent nebular emission predictions for MIST and Padova+Geneva evolutionary tracks.

  15. Modelling population dynamics model formulation, fitting and assessment using state-space methods

    CERN Document Server

    Newman, K B; Morgan, B J T; King, R; Borchers, D L; Cole, D J; Besbeas, P; Gimenez, O; Thomas, L

    2014-01-01

    This book gives a unifying framework for estimating the abundance of open populations: populations subject to births, deaths and movement, given imperfect measurements or samples of the populations.  The focus is primarily on populations of vertebrates for which dynamics are typically modelled within the framework of an annual cycle, and for which stochastic variability in the demographic processes is usually modest. Discrete-time models are developed in which animals can be assigned to discrete states such as age class, gender, maturity,  population (within a metapopulation), or species (for multi-species models). The book goes well beyond estimation of abundance, allowing inference on underlying population processes such as birth or recruitment, survival and movement. This requires the formulation and fitting of population dynamics models.  The resulting fitted models yield both estimates of abundance and estimates of parameters characterizing the underlying processes.  

  16. Interactive, open source, travel time scenario modelling: tools to facilitate participation in health service access analysis.

    Science.gov (United States)

    Fisher, Rohan; Lassa, Jonatan

    2017-04-18

    Modelling travel time to services has become a common public health tool for planning service provision but the usefulness of these analyses is constrained by the availability of accurate input data and limitations inherent in the assumptions and parameterisation. This is particularly an issue in the developing world where access to basic data is limited and travel is often complex and multi-modal. Improving the accuracy and relevance in this context requires greater accessibility to, and flexibility in, travel time modelling tools to facilitate the incorporation of local knowledge and the rapid exploration of multiple travel scenarios. The aim of this work was to develop simple open source, adaptable, interactive travel time modelling tools to allow greater access to and participation in service access analysis. Described are three interconnected applications designed to reduce some of the barriers to the more wide-spread use of GIS analysis of service access and allow for complex spatial and temporal variations in service availability. These applications are an open source GIS tool-kit and two geo-simulation models. The development of these tools was guided by health service issues from a developing world context but they present a general approach to enabling greater access to and flexibility in health access modelling. The tools demonstrate a method that substantially simplifies the process for conducting travel time assessments and demonstrate a dynamic, interactive approach in an open source GIS format. In addition this paper provides examples from empirical experience where these tools have informed better policy and planning. Travel and health service access is complex and cannot be reduced to a few static modeled outputs. The approaches described in this paper use a unique set of tools to explore this complexity, promote discussion and build understanding with the goal of producing better planning outcomes. The accessible, flexible, interactive and

  17. Multiple bifurcations and periodic 'bubbling' in a delay population model

    International Nuclear Information System (INIS)

    Peng Mingshu

    2005-01-01

    In this paper, the flip bifurcation and periodic doubling bifurcations of a discrete population model without delay influence is firstly studied and the phenomenon of Feigenbaum's cascade of periodic doublings is also observed. Secondly, we explored the Neimark-Sacker bifurcation in the delay population model (two-dimension discrete dynamical systems) and the unique stable closed invariant curve which bifurcates from the nontrivial fixed point. Finally, a computer-assisted study for the delay population model is also delved into. Our computer simulation shows that the introduction of delay effect in a nonlinear difference equation derived from the logistic map leads to much richer dynamic behavior, such as stable node → stable focus → an lower-dimensional closed invariant curve (quasi-periodic solution, limit cycle) or/and stable periodic solutions → chaotic attractor by cascading bubbles (the combination of potential period doubling and reverse period-doubling) and the sudden change between two different attractors, etc

  18. Stochastic resonance in a generalized Von Foerster population growth model

    Energy Technology Data Exchange (ETDEWEB)

    Lumi, N.; Mankin, R. [Institute of Mathematics and Natural Sciences, Tallinn University, 25 Narva Road, 10120 Tallinn (Estonia)

    2014-11-12

    The stochastic dynamics of a population growth model, similar to the Von Foerster model for human population, is studied. The influence of fluctuating environment on the carrying capacity is modeled as a multiplicative dichotomous noise. It is established that an interplay between nonlinearity and environmental fluctuations can cause single unidirectional discontinuous transitions of the mean population size versus the noise amplitude, i.e., an increase of noise amplitude can induce a jump from a state with a moderate number of individuals to that with a very large number, while by decreasing the noise amplitude an opposite transition cannot be effected. An analytical expression of the mean escape time for such transitions is found. Particularly, it is shown that the mean transition time exhibits a strong minimum at intermediate values of noise correlation time, i.e., the phenomenon of stochastic resonance occurs. Applications of the results in ecology are also discussed.

  19. Developing Access Control Model of Web OLAP over Trusted and Collaborative Data Warehouses

    Science.gov (United States)

    Fugkeaw, Somchart; Mitrpanont, Jarernsri L.; Manpanpanich, Piyawit; Juntapremjitt, Sekpon

    This paper proposes the design and development of Role- based Access Control (RBAC) model for the Single Sign-On (SSO) Web-OLAP query spanning over multiple data warehouses (DWs). The model is based on PKI Authentication and Privilege Management Infrastructure (PMI); it presents a binding model of RBAC authorization based on dimension privilege specified in attribute certificate (AC) and user identification. Particularly, the way of attribute mapping between DW user authentication and privilege of dimensional access is illustrated. In our approach, we apply the multi-agent system to automate flexible and effective management of user authentication, role delegation as well as system accountability. Finally, the paper culminates in the prototype system A-COLD (Access Control of web-OLAP over multiple DWs) that incorporates the OLAP features and authentication and authorization enforcement in the multi-user and multi-data warehouse environment.

  20. [Adjustment of the Andersen's model to the Mexican context: access to prenatal care].

    Science.gov (United States)

    Tamez-González, Silvia; Valle-Arcos, Rosa Irene; Eibenschutz-Hartman, Catalina; Méndez-Ramírez, Ignacio

    2006-01-01

    The aim of this work was to propose an adjustment to the Model of Andersen who answers better to the social inequality of the population in the Mexico City and allows to evaluate the effect of socioeconomic factors in the access to the prenatal care of a sample stratified according to degree of marginalization. The data come from a study of 663 women, randomly selected from a framework sample of 21,421 homes in Mexico City. This work collects information about factors that affect utilization of health services, as well as predisposing factors (age and socioeconomic level), as enabling factors (education, social support, entitlement, pay out of pocket and opinion of health services), and need factors. The sample was ranked according to exclusion variables into three stratums. The data were analyzed through the technique of path analysis. The results indicate that socioeconomic level takes part like predisposed variable for utilization of prenatal care services into three stratums. Otherwise, education and social support were the most important enabling variables for utilization of prenatal care services in the same three groups. In regard to low stratum, the most important enabling variables were education and entitlement. For high stratum the principal enabling variables were pay out of pocket and social support. The medium stratum shows atypical behavior which it was difficult to explain and understand. There was not mediating role with need variable in three models. This indicated absence of equality in all stratums. However, the most correlations in high stratum perhaps indicate less inequitable conditions regarding other stratums.

  1. An age-structured population balance model for microbial dynamics

    Directory of Open Access Journals (Sweden)

    Duarte M.V.E.

    2003-01-01

    Full Text Available This work presents an age-structured population balance model (ASPBM for a bioprocess in a continuous stirred-tank fermentor. It relates the macroscopic properties and dynamic behavior of biomass to the operational parameters and microscopic properties of cells. Population dynamics is governed by two time- and age-dependent density functions for living and dead cells, accounting for the influence of substrate and dissolved oxygen concentrations on cell division, aging and death processes. The ASPBM described biomass and substrate oscillations in aerobic continuous cultures as experimentally observed. It is noteworthy that a small data set consisting of nonsegregated measurements was sufficient to adjust a complex segregated mathematical model.

  2. A nutrition strategy to reduce the burden of diet related disease: access to dietician services must complement population health approaches.

    Science.gov (United States)

    Segal, Leonie; Opie, Rachelle S

    2015-01-01

    Poor diet quality is implicated in almost every disease and health issue. And yet, in most advanced market economies diet quality is poor, with a minority meeting guidelines for healthy eating. Poor diet is thus responsible for substantial disease burden. Societies have at their disposal a range of strategies to influence diet behaviors. These can be classified into: (i) population level socio-educational approaches to enhance diet knowledge; (ii) pricing incentives (subsidies on healthy foods, punitive taxes on unhealthy foods); (iii) regulations to modify the food environment, and (iv) the provision of clinical dietetic services. There is little evidence that societies are active in implementing the available strategies. Advertising of "junk foods" is largely unchecked, contrasting with strict controls on advertising tobacco products, which also attract punitive taxes. Access to dieticians is restricted in most countries, even in the context of universal health care. In Australia in 2011 there were just 2,969 practicing dieticians/nutritionists or 1.3 clinicians per 10,000 persons, compared with 5.8 physiotherapists per 10,000 persons, 14.8 general practitioners (family physicians) per 10,000 persons or 75 nurses per 10,000 persons. It is time to implement comprehensive national nutrition strategies capable of effecting change. Such strategies need to be multi-component, incorporating both public health approaches and expanded publicly funded dietetic services. Access to individualized dietetic services is needed by those at risk, or with current chronic conditions, given the complexity of the diet message, the need for professional support for behavior change and to reflect individual circumstances. The adoption of a comprehensive nutrition strategy offers the promise of substantial improvement in diet quality, better health and wellbeing and lower health care costs.

  3. A nutrition strategy to reduce the burden of diet related disease: Access to dietician services must complement population health approaches

    Directory of Open Access Journals (Sweden)

    Leonie eSegal

    2015-08-01

    Full Text Available Poor diet quality is implicated in almost every disease and health issue. And yet, in most advanced market economies diet quality is poor, with a minority meeting guidelines for healthy eating. Poor diet is thus responsible for substantial disease burden.Societies have at their disposal a range of strategies to influence diet behaviors. These can be classified into; i population level socio-educational approaches to enhance diet knowledge; ii pricing incentives (subsidies on healthy foods, punitive taxes on unhealthy foods; iii regulations to modify the food environment, and iv the provision of clinical dietetic services. There is little evidence that societies are active in implementing the available strategies. Advertising of ‘junk foods’ is largely unchecked, contrasting with strict controls on advertising tobacco products, which also attract punitive taxes. Access to dieticians is restricted in most countries, even in the context of universal health care. In Australia in 2011 there were just 2,969 practicing dieticians/nutritionists or 1.3 clinicians per 10,000 persons, compared with 5.8 physiotherapists per 10,000 persons, 14.8 general practitioners (family physicians per 10,000 persons or 75 nurses per 10,000 persons.Given the major role of diet in health it is time to implement comprehensive national nutrition strategies capable of effecting change. Such strategies need to be multi-component, incorporating both public health approaches and expanded publicly funded dietetic services. Access to individualized dietetic services is needed by those at risk, or with current chronic conditions, given the complexity of the diet message, the need for professional support for behavior change and to reflect individual circumstances. The adoption of a comprehensive nutrition strategy offers the promise of substantial improvement in diet quality, better health and wellbeing and lower health care costs.

  4. Using a Population Model to Inform the Management of River Flows and Invasive Carp ( Cyprinus carpio)

    Science.gov (United States)

    Koehn, John D.; Todd, Charles R.; Zampatti, Brenton P.; Stuart, Ivor G.; Conallin, Anthony; Thwaites, Leigh; Ye, Qifeng

    2018-03-01

    Carp are a highly successful invasive fish species, now widespread, abundant and considered a pest in south-eastern Australia. To date, most management effort has been directed at reducing abundances of adult fish, with little consideration of population growth through reproduction. Environmental water allocations are now an important option for the rehabilitation of aquatic ecosystems, particularly in the Murray-Darling Basin. As carp respond to flows, there is concern that environmental watering may cause floodplain inundation and provide access to spawning habitats subsequently causing unwanted population increase. This is a management conundrum that needs to be carefully considered within the context of contemporary river flow management (natural, environmental, irrigation). This paper uses a population model to investigate flow-related carp population dynamics for three case studies in the Murray-Darling Basin: (1) river and terminal lakes; (2) wetlands and floodplain lakes; and (3) complex river channel and floodplain system. Results highlight distinctive outcomes depending on site characteristics. In particular, the terminal lakes maintain a significant source carp population regardless of river flow; hence any additional within-channel environmental flows are likely to have little impact on carp populations. In contrast, large-scale removal of carp from the lakes may be beneficial, especially in times of extended low river flows. Case studies 2 and 3 show how wetlands, floodplain lakes and the floodplain itself can now often be inundated for several months over the carp spawning season by high volume flows provided for irrigation or water transfers. Such inundations can be a major driver of carp populations, compared to within channel flows that have relatively little effecton recruitment. The use of a population model that incorporates river flows and different habitats for this flow-responsive species, allows for the comparison of likely population

  5. Modeling and Recognizing Policy Conflicts with Resource Access Requests on Protected Health Information

    Directory of Open Access Journals (Sweden)

    Raik Kuhlisch

    2017-07-01

    Full Text Available This article discusses potential clashes between different types of security policies that regulate resource access requests on clinical patient data in hospitals by employees. Attribute-based Access Control (ABAC is proposed as a proper means for such regulation. A proper representation of ABAC policies must include a handling of policy attributes among different policy types. In this article, we propose a semantic policy model with predefined policy conflict categories. A conformance verification function detects erroneous, clashing or mutually susceptible rules early during the policy planning phase. The model and conflicts are used in a conceptual application environment and evaluated in a technical experiment during an interoperability test event.

  6. Gaining Access to Hidden Populations: Strategies for Gaining Cooperation of Drug Sellers/Dealers and Their Families in Ethnographic Research

    Science.gov (United States)

    Dunlap, Eloise; Johnson, Bruce D.

    2009-01-01

    respect and honesty. Since drug dealers' self-esteem and prestige is generally tied to their drug dealing activities, signs of respect are critical in obtaining repeated appointments and conversations. Issues such as levels of rejection and how to use apparent refusal to the ethnographer's advantage are discussed. Gaining access was broken into two components. One involved permission to engage dealers in in-depth interviews The next involved obtaining permission to directly observe the actual activities of selling. Both of these components were important elements in gaining access and permission to conduct research. Building and maintaining trust and rapport were related to issues of confidentiality and anonymity. Ill-fated ethnographic strategies, such as relying on street drug users for introductions, were important stepping stones to those strategies that did work. Such strategies revealed the level of interaction between dealer and user. They helped to uncover drug subculture behavior patterns and conduct norms and to tease out the relationship between the dealer and user. Such strategies also revealed hierarchical arrangements and the loyalty within such levels. Those near the top of dealer hierarchies generally are reluctant to introduce their boss (those above them in rank) because of fear of reprisals, a sense of responsibility to the individual boss, or/and a sense of loyalty to the organization. The strategies laid out were experienced in New York and may be adjusted to acquire access to hidden populations in other situations. PMID:19809526

  7. Improving access to health care for chronic hepatitis B among migrant Chinese populations: A systematic mixed methods review of barriers and enablers.

    Science.gov (United States)

    Vedio, A; Liu, E Z H; Lee, A C K; Salway, S

    2017-07-01

    Migrant Chinese populations in Western countries have a high prevalence of chronic hepatitis B but often experience poor access to health care and late diagnosis. This systematic review aimed to identify obstacles and supports to timely and appropriate health service use among these populations. Systematic searches resulted in 48 relevant studies published between 1996 and 2015. Data extraction and synthesis were informed by models of healthcare access that highlight the interplay of patient, provider and health system factors. There was strong consistent evidence of low levels of knowledge among patients and community members; but interventions that were primarily focused on increasing knowledge had only modest positive effects on testing and/or vaccination. There was strong consistent evidence that Chinese migrants tend to misunderstand the need for health care for hepatitis B and have low satisfaction with services. Stigma was consistently associated with hepatitis B, and there was weak but consistent evidence of stigma acting as a barrier to care. However, available evidence on the effects of providing culturally appropriate services for hepatitis B on increasing uptake is limited. There was strong consistent evidence that health professionals miss opportunities for testing and vaccination. Practitioner education interventions may be important, but evidence of effectiveness is limited. A simple prompt in patient records for primary care physicians improved the uptake of testing, and a dedicated service increased targeted vaccination coverage for newborns. Further development and more rigorous evaluation of more holistic approaches that address patient, provider and system obstacles are needed. © 2017 The Authors. Journal of Viral Hepatitis Published by John Wiley & Sons Ltd.

  8. Incorporating parametric uncertainty into population viability analysis models

    Science.gov (United States)

    McGowan, Conor P.; Runge, Michael C.; Larson, Michael A.

    2011-01-01

    Uncertainty in parameter estimates from sampling variation or expert judgment can introduce substantial uncertainty into ecological predictions based on those estimates. However, in standard population viability analyses, one of the most widely used tools for managing plant, fish and wildlife populations, parametric uncertainty is often ignored in or discarded from model projections. We present a method for explicitly incorporating this source of uncertainty into population models to fully account for risk in management and decision contexts. Our method involves a two-step simulation process where parametric uncertainty is incorporated into the replication loop of the model and temporal variance is incorporated into the loop for time steps in the model. Using the piping plover, a federally threatened shorebird in the USA and Canada, as an example, we compare abundance projections and extinction probabilities from simulations that exclude and include parametric uncertainty. Although final abundance was very low for all sets of simulations, estimated extinction risk was much greater for the simulation that incorporated parametric uncertainty in the replication loop. Decisions about species conservation (e.g., listing, delisting, and jeopardy) might differ greatly depending on the treatment of parametric uncertainty in population models.

  9. GIS-Based Population Model Applied to Nevada Transportation Routes

    International Nuclear Information System (INIS)

    Mills, G.S.; Neuhauser, K.S.

    1999-01-01

    Recently, a model based on geographic information system (GIS) processing of US Census Block data has made high-resolution population analysis for transportation risk analysis technically and economically feasible. Population density bordering each kilometer of a route may be tabulated with specific route sections falling into each of three categories (Rural, Suburban or Urban) identified for separate risk analysis. In addition to the improvement in resolution of Urban areas along a route, the model provides a statistically-based correction to population densities in Rural and Suburban areas where Census Block dimensions may greatly exceed the 800-meter scale of interest. A semi-automated application of the GIS model to a subset of routes in Nevada (related to the Yucca Mountain project) are presented, and the results compared to previous models including a model based on published Census and other data. These comparisons demonstrate that meaningful improvement in accuracy and specificity of transportation risk analyses is dependent on correspondingly accurate and geographically-specific population density data

  10. Models of Eucalypt phenology predict bat population flux.

    Science.gov (United States)

    Giles, John R; Plowright, Raina K; Eby, Peggy; Peel, Alison J; McCallum, Hamish

    2016-10-01

    Fruit bats (Pteropodidae) have received increased attention after the recent emergence of notable viral pathogens of bat origin. Their vagility hinders data collection on abundance and distribution, which constrains modeling efforts and our understanding of bat ecology, viral dynamics, and spillover. We addressed this knowledge gap with models and data on the occurrence and abundance of nectarivorous fruit bat populations at 3 day roosts in southeast Queensland. We used environmental drivers of nectar production as predictors and explored relationships between bat abundance and virus spillover. Specifically, we developed several novel modeling tools motivated by complexities of fruit bat foraging ecology, including: (1) a dataset of spatial variables comprising Eucalypt-focused vegetation indices, cumulative precipitation, and temperature anomaly; (2) an algorithm that associated bat population response with spatial covariates in a spatially and temporally relevant way given our current understanding of bat foraging behavior; and (3) a thorough statistical learning approach to finding optimal covariate combinations. We identified covariates that classify fruit bat occupancy at each of our three study roosts with 86-93% accuracy. Negative binomial models explained 43-53% of the variation in observed abundance across roosts. Our models suggest that spatiotemporal heterogeneity in Eucalypt-based food resources could drive at least 50% of bat population behavior at the landscape scale. We found that 13 spillover events were observed within the foraging range of our study roosts, and they occurred during times when models predicted low population abundance. Our results suggest that, in southeast Queensland, spillover may not be driven by large aggregations of fruit bats attracted by nectar-based resources, but rather by behavior of smaller resident subpopulations. Our models and data integrated remote sensing and statistical learning to make inferences on bat ecology

  11. Tractable Stochastic Geometry Model for IoT Access in LTE Networks

    KAUST Repository

    Gharbieh, Mohammad; Elsawy, Hesham; Bader, Ahmed; Alouini, Mohamed-Slim

    2017-01-01

    The Internet of Things (IoT) is large-scale by nature. This is not only manifested by the large number of connected devices, but also by the high volumes of traffic that must be accommodated. Cellular networks are indeed a natural candidate for the data tsunami the IoT is expected to generate in conjunction with legacy human-type traffic. However, the random access process for scheduling request represents a major bottleneck to support IoT via LTE cellular networks. Accordingly, this paper develops a mathematical framework to model and study the random access channel (RACH) scalability to accommodate IoT traffic. The developed model is based on stochastic geometry and discrete time Markov chains (DTMC) to account for different access strategies and possible sources of inter-cell and intra-cell interferences. To this end, the developed model is utilized to assess and compare three different access strategies, which incorporate a combination of transmission persistency, back-off, and power ramping. The analysis and the results showcased herewith clearly illustrate the vulnerability of the random access procedure as the IoT intensity grows. Finally, the paper offers insights into effective scenarios for each transmission strategy in terms of IoT intensity and RACH detection thresholds.

  12. Tractable Stochastic Geometry Model for IoT Access in LTE Networks

    KAUST Repository

    Gharbieh, Mohammad

    2017-02-07

    The Internet of Things (IoT) is large-scale by nature. This is not only manifested by the large number of connected devices, but also by the high volumes of traffic that must be accommodated. Cellular networks are indeed a natural candidate for the data tsunami the IoT is expected to generate in conjunction with legacy human-type traffic. However, the random access process for scheduling request represents a major bottleneck to support IoT via LTE cellular networks. Accordingly, this paper develops a mathematical framework to model and study the random access channel (RACH) scalability to accommodate IoT traffic. The developed model is based on stochastic geometry and discrete time Markov chains (DTMC) to account for different access strategies and possible sources of inter-cell and intra-cell interferences. To this end, the developed model is utilized to assess and compare three different access strategies, which incorporate a combination of transmission persistency, back-off, and power ramping. The analysis and the results showcased herewith clearly illustrate the vulnerability of the random access procedure as the IoT intensity grows. Finally, the paper offers insights into effective scenarios for each transmission strategy in terms of IoT intensity and RACH detection thresholds.

  13. An inbreeding model of associative overdominance during a population bottleneck.

    Science.gov (United States)

    Bierne, N; Tsitrone, A; David, P

    2000-08-01

    Associative overdominance, the fitness difference between heterozygotes and homozygotes at a neutral locus, is classically described using two categories of models: linkage disequilibrium in small populations or identity disequilibrium in infinite, partially selfing populations. In both cases, only equilibrium situations have been considered. In the present study, associative overdominance is related to the distribution of individual inbreeding levels (i.e., genomic autozygosity). Our model integrates the effects of physical linkage and variation in inbreeding history among individual pedigrees. Hence, linkage and identity disequilibrium, traditionally presented as alternatives, are summarized within a single framework. This allows studying nonequilibrium situations in which both occur simultaneously. The model is applied to the case of an infinite population undergoing a sustained population bottleneck. The effects of bottleneck size, mating system, marker gene diversity, deleterious genomic mutation parameters, and physical linkage are evaluated. Bottlenecks transiently generate much larger associative overdominance than observed in equilibrium finite populations and represent a plausible explanation of empirical results obtained, for instance, in marine species. Moreover, the main origin of associative overdominance is random variation in individual inbreeding whereas physical linkage has little effect.

  14. The comparison of spatial accessibility measures between non-obstacle and obstacle oriented based on gravity model

    Science.gov (United States)

    Han, Zhi-Gang; Cui, Cai-Hui

    2009-10-01

    Spatial accessibility denotes the ease with which activities may be reached from a given location using a particular transportation system. There are a number of accessibility measures methods and models, such as time of access to city centre, mean travel costs and opportunity accessibility. But these methods or models ignore the existence of obstacles. In fact, there are many kinds of obstacles in the world, such as rivers, railways, etc. The paper reviews the progress of accessibility measures, and introduces the obstacle to the accessibility measures. Meanwhile, through the analysis of A* algorithm, the advantage of A* algorithm that could avoid obstacles is put forward. Based on the above mentioned, the obstacle oriented accessibility measures based on simple gravity model is discussed in details. Finally, a case study is fulfilled by comparison between the obstacle oriented and non-obstacle accessibility measures.

  15. Learning with Admixture: Modeling, Optimization, and Applications in Population Genetics

    DEFF Research Database (Denmark)

    Cheng, Jade Yu

    2016-01-01

    the foundation for both CoalHMM and Ohana. Optimization modeling has been the main theme throughout my PhD, and it will continue to shape my work for the years to come. The algorithms and software I developed to study historical admixture and population evolution fall into a larger family of machine learning...... geneticists strive to establish working solutions to extract information from massive volumes of biological data. The steep increase in the quantity and quality of genomic data during the past decades provides a unique opportunity but also calls for new and improved algorithms and software to cope...... including population splits, effective population sizes, gene flow, etc. Since joining the CoalHMM development team in 2014, I have mainly contributed in two directions: 1) improving optimizations through heuristic-based evolutionary algorithms and 2) modeling of historical admixture events. Ohana, meaning...

  16. Stochastic population and epidemic models persistence and extinction

    CERN Document Server

    Allen, Linda J S

    2015-01-01

    This monograph provides a summary of the basic theory of branching processes for single-type and multi-type processes. Classic examples of population and epidemic models illustrate the probability of population or epidemic extinction obtained from the theory of branching processes. The first chapter develops the branching process theory, while in the second chapter two applications to population and epidemic processes of single-type branching process theory are explored. The last two chapters present multi-type branching process applications to epidemic models, and then continuous-time and continuous-state branching processes with applications. In addition, several MATLAB programs for simulating stochastic sample paths  are provided in an Appendix. These notes originated as part of a lecture series on Stochastics in Biological Systems at the Mathematical Biosciences Institute in Ohio, USA. Professor Linda Allen is a Paul Whitfield Horn Professor of Mathematics in the Department of Mathematics and Statistics ...

  17. Difficulties in accessing and availing of public health care systems among rural population in Chittoor District, Andhra Pradesh

    OpenAIRE

    Geetha Lakshmi Sreerama; Sai Varun Matavalum; Paraiveedu Arumugam Chandresekharan; Veronica Thunga

    2015-01-01

    Context: Despite policies to make health care accessible to all, it is not universally accessible. Frequent evaluation of barriers to accessibility of health care services paves path for improvement. Hence, present study is undertaken to evaluate the factors and public health policies influencing health care access to rural people in Chittoor District, Andhra Pradesh, which can be interpolated for other regions. Aims: To assess knowledge, perceptions, availing of public health care services, ...

  18. Modeling population exposures to silver nanoparticles present in consumer products

    Science.gov (United States)

    Royce, Steven G.; Mukherjee, Dwaipayan; Cai, Ting; Xu, Shu S.; Alexander, Jocelyn A.; Mi, Zhongyuan; Calderon, Leonardo; Mainelis, Gediminas; Lee, KiBum; Lioy, Paul J.; Tetley, Teresa D.; Chung, Kian Fan; Zhang, Junfeng; Georgopoulos, Panos G.

    2014-11-01

    Exposures of the general population to manufactured nanoparticles (MNPs) are expected to keep rising due to increasing use of MNPs in common consumer products (PEN 2014). The present study focuses on characterizing ambient and indoor population exposures to silver MNPs (nAg). For situations where detailed, case-specific exposure-related data are not available, as in the present study, a novel tiered modeling system, Prioritization/Ranking of Toxic Exposures with GIS (geographic information system) Extension (PRoTEGE), has been developed: it employs a product life cycle analysis (LCA) approach coupled with basic human life stage analysis (LSA) to characterize potential exposures to chemicals of current and emerging concern. The PRoTEGE system has been implemented for ambient and indoor environments, utilizing available MNP production, usage, and properties databases, along with laboratory measurements of potential personal exposures from consumer spray products containing nAg. Modeling of environmental and microenvironmental levels of MNPs employs probabilistic material flow analysis combined with product LCA to account for releases during manufacturing, transport, usage, disposal, etc. Human exposure and dose characterization further employ screening microenvironmental modeling and intake fraction methods combined with LSA for potentially exposed populations, to assess differences associated with gender, age, and demographics. Population distributions of intakes, estimated using the PRoTEGE framework, are consistent with published individual-based intake estimates, demonstrating that PRoTEGE is capable of capturing realistic exposure scenarios for the US population. Distributions of intakes are also used to calculate biologically relevant population distributions of uptakes and target tissue doses through human airway dosimetry modeling that takes into account product MNP size distributions and age-relevant physiological parameters.

  19. Population models for time-varying pesticide exposure

    NARCIS (Netherlands)

    Jager T; Jong FMW de; Traas TP; LER; SEC

    2007-01-01

    A model has recently been developed at RIVM to predict the effects of variable exposure to pesticides of plant and animal populations in surface water. Before a pesticide is placed on the market, the environmental risk of the substance has to be assessed. This risk is estimated by comparing

  20. Individual based model of slug population and spatial dynamics

    NARCIS (Netherlands)

    Choi, Y.H.; Bohan, D.A.; Potting, R.P.J.; Semenov, M.A.; Glen, D.M.

    2006-01-01

    The slug, Deroceras reticulatum, is one of the most important pests of agricultural and horticultural crops in UK and Europe. In this paper, a spatially explicit individual based model (IbM) is developed to study the dynamics of a population of D. reticulatum. The IbM establishes a virtual field

  1. Community clinic offers access to care. A system and a city collaborate to care for an immigrant population.

    Science.gov (United States)

    Bauer, S

    1993-10-01

    The Southwest Community Health Clinic (SCHC) has been providing free preventive healthcare to the poor residents of its Houston neighborhood since June 1991. Sponsored by the Sisters of Charity of the Incarnate Word Health Care System and the city of Houston, the clinic invites healing through hospitality, unlike many free clinics. The family-focused clinic takes a multidisciplinary team approach to preventive healthcare. The staff of approximately 30 healthcare professionals provides prenatal and pediatric care; immunizations; tuberculosis screenings; and a variety of social services for patients' physical, emotional, and spiritual needs. SCHC's well-child program screens children from birth through age five for physical and developmental problems. Clinic staff teach and guide parents on their children's health. The program stresses early identification of developmental delays and disabilities, with referral to appropriate services. SCHC has also implemented a tuberculosis testing program to prevent spread of the disease. Persons who test positive are referred to the City of Houston Department of Health and Human Service's chest clinics for follow-up and treatment. Community outreach is a major ingredient of SCHC's preventive healthcare program. A community health advocate, who is familiar with the cultures, traditions, and languages of the population being served, identifies families needing care and supports their access and use of healthcare services.

  2. Federated Access Control in Heterogeneous Intercloud Environment: Basic Models and Architecture Patterns

    NARCIS (Netherlands)

    Demchenko, Y.; Ngo, C.; de Laat, C.; Lee, C.

    2014-01-01

    This paper presents on-going research to define the basic models and architecture patterns for federated access control in heterogeneous (multi-provider) multi-cloud and inter-cloud environment. The proposed research contributes to the further definition of Intercloud Federation Framework (ICFF)

  3. Background and Theory Behind the Compensation, Accessions, and Personnel Management (CAPM) Model

    National Research Council Canada - National Science Library

    Ausink, John; Cave, Jonathan; Carrillo, Manuel

    2003-01-01

    .... This report descries the Compensation, Accession, and Personnel Management (CAPM) model, which was developed to be a relatively easy-to-use personal computer-based analytical tool that would enable decisionmakers to study the effects of changes in policy on retention behavior and future inventories of military personnel.

  4. The relationship between accessibility of healthcare facilities and medical care utilization among the middle-aged and elderly population in Taiwan.

    Science.gov (United States)

    Yang, Ya-Ting; Iqbal, Usman; Ko, Hua-Lin; Wu, Chia-Rong; Chiu, Hsien-Tsai; Lin, Yi-Chieh; Lin, Wender; Elsa Hsu, Yi-Hsin

    2015-06-01

    The purpose of this study was to explore the relationship between accessibility of healthcare facilities and medical care utilization among the middle-aged and elderly population in Taiwan. Cross-sectional study from 2007 Taiwan Longitudinal Study on Ageing (TLSA) survey. Community-based study. A total of 4249 middle-aged and elderly subjects were recruited. None. Outpatient visits within 1 month, and hospitalization, emergency visits as well as to shop in pharmacy stores within 1 year, respectively. Adjusting for important confounding variables, the middle-aged and elderly with National Health Insurance (NHI) and commercial insurance compared with those with NHI alone tended to have outpatient visits. The middle-aged and elderly with longer time to access healthcare facilities were less likely to shop in pharmacy stores compared with those with shop in pharmacy stores compared with those with perceived convenience. Our study of Taiwan's experience could provide a valuable lesson for countries that are planning to launch universal health insurance system, locate budgets in health care and transportation. The middle-aged and elderly who were facing more challenges in accessing health care, no matter in perceived accessibility or real time to access health care, had less outpatient visits and more drug stores shopping. Strategic policies are needed to improve accessibility in increasing patients' perception on access and escalating convenience of transportation system for improving accessibility. © The Author 2015. Published by Oxford University Press in association with the International Society for Quality in Health Care; all rights reserved.

  5. Mapping of the stochastic Lotka-Volterra model to models of population genetics and game theory

    Science.gov (United States)

    Constable, George W. A.; McKane, Alan J.

    2017-08-01

    The relationship between the M -species stochastic Lotka-Volterra competition (SLVC) model and the M -allele Moran model of population genetics is explored via timescale separation arguments. When selection for species is weak and the population size is large but finite, precise conditions are determined for the stochastic dynamics of the SLVC model to be mappable to the neutral Moran model, the Moran model with frequency-independent selection, and the Moran model with frequency-dependent selection (equivalently a game-theoretic formulation of the Moran model). We demonstrate how these mappings can be used to calculate extinction probabilities and the times until a species' extinction in the SLVC model.

  6. GalMod: the last frontier of Galaxy population synthesis models

    Science.gov (United States)

    Pasetto, Stefano; Kollmeier, Juna; Grebel, Eva K.; chiosi, cesare

    2018-01-01

    We present a novel Galaxy population synthesis model: GalMod (Pasetto et al. 2016, 2017a,b) is the only star-count model featuring an asymmetric bar/bulge as well as spiral arms as directly obtained by applying linear perturbative theory to self-consistent distribution function of the Galaxy stellar populations. Compared to previous literature models (e.g., Besancon, Trilegal), GalMod allows to generate full-sky mock catalogue, M31 surveys and provides a better match to observed Milky Way (MW) stellar fields.The model can generate synthetic mock catalogs of visible portions of the MW, external galaxies like M31, or N-body simulation initial conditions. At any given time, e.g., a chosen age of the Galaxy, the model contains a sum of discrete stellar populations, namely bulge/bar, disk, halo. The disk population is itself the sum of subpopulations: spiral arms, thin disk, thick disk, and gas component, while the halo is modeled as the sum of a stellar component, a hot coronal gas, and a dark matter component. The Galactic potential is computed from these subpopulations' density profiles and used to generate detailed kinematics by considering the first few moments of the Boltzmann collisionless equation for all the stellar subpopulations. The same density profiles are then used to define the observed color-magnitude diagrams within an input field of view from an arbitrary solar location. Several photometric systems have been included and made available on-line, e.g., SDSS, Gaia, 2MASS, HST WFC3, and others. Finally, we model the extinction with advanced ray tracing solutions.The model's web page (and tutorial) can be accessed at www.GalMod.org.

  7. ORDEM2010 and MASTER-2009 Modeled Small Debris Population Comparison

    Science.gov (United States)

    Krisko, Paula H.; Flegel, S.

    2010-01-01

    The latest versions of the two premier orbital debris engineering models, NASA s ORDEM2010 and ESA s MASTER-2009, have been publicly released. Both models have gone through significant advancements since inception, and now represent the state-of-the-art in orbital debris knowledge of their respective agencies. The purpose of these models is to provide satellite designers/operators and debris researchers with reliable estimates of the artificial debris environment in near-Earth orbit. The small debris environment within the size range of 1 mm to 1 cm is of particular interest to both human and robotic spacecraft programs. These objects are much more numerous than larger trackable debris but are still large enough to cause significant, if not catastrophic, damage to spacecraft upon impact. They are also small enough to elude routine detection by existing observation systems (radar and telescope). Without reliable detection the modeling of these populations has always coupled theoretical origins with supporting observational data in different degrees. This paper details the 1 mm to 1 cm orbital debris populations of both ORDEM2010 and MASTER-2009; their sources (both known and presumed), current supporting data and theory, and methods of population analysis. Fluxes on spacecraft for chosen orbits are also presented and discussed within the context of each model.

  8. A sustainable business model for Open-Access journal publishing a proposed plan for High-Energy Physics

    CERN Document Server

    Vigen, Jens

    2007-01-01

    The High Energy Physics community over the last 15 years has achieved so-called full green Open Access through the wide dissemination of preprints via arXiv, a central subject repository managed by Cornell University. However, green Open Access does not alleviate the economic difficulties of libraries as they are still expected to offer access to versions of record of the peer-reviewed literature. For this reason the particle physics community is now addressing the issue of gold Open Access by converting a set of the existing core journals to Open Access. A Working Party has been established to bring together funding agencies, laboratories and libraries into a single consortium, called SCOAP3 (Sponsoring Consortium for Open Access Publishing in Particle Physics). This consortium will engage with publishers to build a sustainable model for Open Access publishing. In this model, subscription fees from multiple institutions are replaced by contracts with publishers of Open Access journals, where the SCOAP3 conso...

  9. Cloud Geospatial Analysis Tools for Global-Scale Comparisons of Population Models for Decision Making

    Science.gov (United States)

    Hancher, M.; Lieber, A.; Scott, L.

    2017-12-01

    The volume of satellite and other Earth data is growing rapidly. Combined with information about where people are, these data can inform decisions in a range of areas including food and water security, disease and disaster risk management, biodiversity, and climate adaptation. Google's platform for planetary-scale geospatial data analysis, Earth Engine, grants access to petabytes of continually updating Earth data, programming interfaces for analyzing the data without the need to download and manage it, and mechanisms for sharing the analyses and publishing results for data-driven decision making. In addition to data about the planet, data about the human planet - population, settlement and urban models - are now available for global scale analysis. The Earth Engine APIs enable these data to be joined, combined or visualized with economic or environmental indicators such as nighttime lights trends, global surface water, or climate projections, in the browser without the need to download anything. We will present our newly developed application intended to serve as a resource for government agencies, disaster response and public health programs, or other consumers of these data to quickly visualize the different population models, and compare them to ground truth tabular data to determine which model suits their immediate needs. Users can further tap into the power of Earth Engine and other Google technologies to perform a range of analysis from simple statistics in custom regions to more complex machine learning models. We will highlight case studies in which organizations around the world have used Earth Engine to combine population data with multiple other sources of data, such as water resources and roads data, over deep stacks of temporal imagery to model disease risk and accessibility to inform decisions.

  10. Negative binomial models for abundance estimation of multiple closed populations

    Science.gov (United States)

    Boyce, Mark S.; MacKenzie, Darry I.; Manly, Bryan F.J.; Haroldson, Mark A.; Moody, David W.

    2001-01-01

    Counts of uniquely identified individuals in a population offer opportunities to estimate abundance. However, for various reasons such counts may be burdened by heterogeneity in the probability of being detected. Theoretical arguments and empirical evidence demonstrate that the negative binomial distribution (NBD) is a useful characterization for counts from biological populations with heterogeneity. We propose a method that focuses on estimating multiple populations by simultaneously using a suite of models derived from the NBD. We used this approach to estimate the number of female grizzly bears (Ursus arctos) with cubs-of-the-year in the Yellowstone ecosystem, for each year, 1986-1998. Akaike's Information Criteria (AIC) indicated that a negative binomial model with a constant level of heterogeneity across all years was best for characterizing the sighting frequencies of female grizzly bears. A lack-of-fit test indicated the model adequately described the collected data. Bootstrap techniques were used to estimate standard errors and 95% confidence intervals. We provide a Monte Carlo technique, which confirms that the Yellowstone ecosystem grizzly bear population increased during the period 1986-1998.

  11. Stochastic population oscillations in spatial predator-prey models

    International Nuclear Information System (INIS)

    Taeuber, Uwe C

    2011-01-01

    It is well-established that including spatial structure and stochastic noise in models for predator-prey interactions invalidates the classical deterministic Lotka-Volterra picture of neutral population cycles. In contrast, stochastic models yield long-lived, but ultimately decaying erratic population oscillations, which can be understood through a resonant amplification mechanism for density fluctuations. In Monte Carlo simulations of spatial stochastic predator-prey systems, one observes striking complex spatio-temporal structures. These spreading activity fronts induce persistent correlations between predators and prey. In the presence of local particle density restrictions (finite prey carrying capacity), there exists an extinction threshold for the predator population. The accompanying continuous non-equilibrium phase transition is governed by the directed-percolation universality class. We employ field-theoretic methods based on the Doi-Peliti representation of the master equation for stochastic particle interaction models to (i) map the ensuing action in the vicinity of the absorbing state phase transition to Reggeon field theory, and (ii) to quantitatively address fluctuation-induced renormalizations of the population oscillation frequency, damping, and diffusion coefficients in the species coexistence phase.

  12. Consistency maintenance for constraint in role-based access control model

    Institute of Scientific and Technical Information of China (English)

    韩伟力; 陈刚; 尹建伟; 董金祥

    2002-01-01

    Constraint is an important aspect of role-based access control and is sometimes argued to be the principal motivation for role-based access control (RBAC). But so far few authors have discussed consistency maintenance for constraint in RBAC model. Based on researches of constraints among roles and types of inconsistency among constraints, this paper introduces corresponding formal rules, rule-based reasoning and corresponding methods to detect, avoid and resolve these inconsistencies. Finally, the paper introduces briefly the application of consistency maintenance in ZD-PDM, an enterprise-oriented product data management (PDM) system.

  13. Consistency maintenance for constraint in role-based access control model

    Institute of Scientific and Technical Information of China (English)

    韩伟力; 陈刚; 尹建伟; 董金祥

    2002-01-01

    Constraint is an important aspect of role-based access control and is sometimes argued to be the principal motivation for role-based access control (RBAC). But so far'few authors have discussed consistency maintenance for constraint in RBAC model. Based on researches of constraints among roles and types of inconsistency among constraints, this paper introduces correaponding formal rules, rulebased reasoning and corresponding methods to detect, avoid and resolve these inconsistencies. Finally,the paper introduces briefly the application of consistency maintenance in ZD-PDM, an enterprise-ori-ented product data management (PDM) system.

  14. Access Control Mechanism for IoT Environments Based on Modelling Communication Procedures as Resources

    OpenAIRE

    Luis Cruz-Piris; Diego Rivera; Ivan Marsa-Maestre; Enrique de la Hoz; Juan R. Velasco

    2018-01-01

    Internet growth has generated new types of services where the use of sensors and actuators is especially remarkable. These services compose what is known as the Internet of Things (IoT). One of the biggest current challenges is obtaining a safe and easy access control scheme for the data managed in these services. We propose integrating IoT devices in an access control system designed for Web-based services by modelling certain IoT communication elements as resources. This would allow us to o...

  15. Preventing Noise-Induced Extinction in Discrete Population Models

    Directory of Open Access Journals (Sweden)

    Irina Bashkirtseva

    2017-01-01

    Full Text Available A problem of the analysis and prevention of noise-induced extinction in nonlinear population models is considered. For the solution of this problem, we suggest a general approach based on the stochastic sensitivity analysis. To prevent the noise-induced extinction, we construct feedback regulators which provide a low stochastic sensitivity and keep the system close to the safe equilibrium regime. For the demonstration of this approach, we apply our mathematical technique to the conceptual but quite representative Ricker-type models. A variant of the Ricker model with delay is studied along with the classic widely used one-dimensional system.

  16. Global asymptotic stability of density dependent integral population projection models.

    Science.gov (United States)

    Rebarber, Richard; Tenhumberg, Brigitte; Townley, Stuart

    2012-02-01

    Many stage-structured density dependent populations with a continuum of stages can be naturally modeled using nonlinear integral projection models. In this paper, we study a trichotomy of global stability result for a class of density dependent systems which include a Platte thistle model. Specifically, we identify those systems parameters for which zero is globally asymptotically stable, parameters for which there is a positive asymptotically stable equilibrium, and parameters for which there is no asymptotically stable equilibrium. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Defense of single-factor models of population regulation

    International Nuclear Information System (INIS)

    Tamarin, R.H.

    1978-01-01

    I reject a multifactorial approach to the study of the regulation of animal populations for two reasons. First, a mechanism suggested by Chitty, that has natural selection at its base, has not been adequately tested. Second, the multifactorial model suggested by Lidicker is untestable because of its vagueness. As a middle ground, I suggest a model that has natural selection as its mechanism, but is multifacturial because it allows many parameters to be the selective agents. I particularly emphasize prediction and selective dispersal. Methods to test this model are suggested

  18. A Bayesian approach to identifying and compensating for model misspecification in population models.

    Science.gov (United States)

    Thorson, James T; Ono, Kotaro; Munch, Stephan B

    2014-02-01

    State-space estimation methods are increasingly used in ecology to estimate productivity and abundance of natural populations while accounting for variability in both population dynamics and measurement processes. However, functional forms for population dynamics and density dependence often will not match the true biological process, and this may degrade the performance of state-space methods. We therefore developed a Bayesian semiparametric state-space model, which uses a Gaussian process (GP) to approximate the population growth function. This offers two benefits for population modeling. First, it allows data to update a specified "prior" on the population growth function, while reverting to this prior when data are uninformative. Second, it allows variability in population dynamics to be decomposed into random errors around the population growth function ("process error") and errors due to the mismatch between the specified prior and estimated growth function ("model error"). We used simulation modeling to illustrate the utility of GP methods in state-space population dynamics models. Results confirmed that the GP model performs similarly to a conventional state-space model when either (1) the prior matches the true process or (2) data are relatively uninformative. However, GP methods improve estimates of the population growth function when the function is misspecified. Results also demonstrated that the estimated magnitude of "model error" can be used to distinguish cases of model misspecification. We conclude with a discussion of the prospects for GP methods in other state-space models, including age and length-structured, meta-analytic, and individual-movement models.

  19. Socio Economic Position in TB Prevalence and Access to Services: Results from a Population Prevalence Survey and a Facility-Based Survey in Bangladesh

    NARCIS (Netherlands)

    Hossain, Shahed; Quaiyum, Mohammad Abdul; Zaman, Khalequ; Banu, Sayera; Husain, Mohammad Ashaque; Islam, Mohammad Akramul; Cooreman, Erwin; Borgdorff, Martien; Lönnroth, Knut; Salim, Abdul Hamid; van Leth, Frank

    2012-01-01

    Background: In Bangladesh DOTS has been provided free of charge since 1993, yet information on access to TB services by different population group is not well documented. The objective of this study was to assess and compare the socio economic position (SEP) of actively detected cases from the

  20. 'If she is a good woman …' and 'to be a real man …': gender, risk and access to HIV services among key populations in Tajikistan.

    Science.gov (United States)

    King, Elizabeth J; Maksymenko, Kateryna M; Almodovar-Diaz, Yadira; Johnson, Sarah

    2016-01-01

    The HIV epidemic continues to grow in Tajikistan, especially among people who inject drugs, sex workers, men who have sex with men and incarcerated populations. Despite their susceptibility to HIV, members of these groups do not always have access to HIV prevention, testing and treatment. The purpose of this study was to identify and understand the gender constraints in accessing HIV services for key populations in Tajikistan. Using focus-group discussions and key-informant interviews the assessment team collected information from members of key populations and those who work with them. Several themes emerged from the data, including: low levels of HIV knowledge, gender constraints to condom use and safer drug use, gender constraints limit HIV testing opportunities, gender-based violence, stigma and discrimination, and the lack of female spaces in the HIV response. The results of this study show that there are well-defined gender norms in Tajikistan, and these gender norms influence key populations' access to HIV services. Addressing these gender constraints may offer opportunities for more equitable access to HIV services in Tajikistan.

  1. Assessing the model transferability for prediction of transcription factor binding sites based on chromatin accessibility.

    Science.gov (United States)

    Liu, Sheng; Zibetti, Cristina; Wan, Jun; Wang, Guohua; Blackshaw, Seth; Qian, Jiang

    2017-07-27

    Computational prediction of transcription factor (TF) binding sites in different cell types is challenging. Recent technology development allows us to determine the genome-wide chromatin accessibility in various cellular and developmental contexts. The chromatin accessibility profiles provide useful information in prediction of TF binding events in various physiological conditions. Furthermore, ChIP-Seq analysis was used to determine genome-wide binding sites for a range of different TFs in multiple cell types. Integration of these two types of genomic information can improve the prediction of TF binding events. We assessed to what extent a model built upon on other TFs and/or other cell types could be used to predict the binding sites of TFs of interest. A random forest model was built using a set of cell type-independent features such as specific sequences recognized by the TFs and evolutionary conservation, as well as cell type-specific features derived from chromatin accessibility data. Our analysis suggested that the models learned from other TFs and/or cell lines performed almost as well as the model learned from the target TF in the cell type of interest. Interestingly, models based on multiple TFs performed better than single-TF models. Finally, we proposed a universal model, BPAC, which was generated using ChIP-Seq data from multiple TFs in various cell types. Integrating chromatin accessibility information with sequence information improves prediction of TF binding.The prediction of TF binding is transferable across TFs and/or cell lines suggesting there are a set of universal "rules". A computational tool was developed to predict TF binding sites based on the universal "rules".

  2. TRBAC:基于信任的访问控制模型%TRBAC: Trust Based Access Control Model

    Institute of Scientific and Technical Information of China (English)

    刘武; 段海新; 张洪; 任萍; 吴建平

    2011-01-01

    访问控制是根据网络用户的身份或属性,对该用户执行某些操作或访问某些网络资源进行控制的过程.对现有访问控制模型进行分析,并针对其不足对RBAC模型进行了扩展,提出了基于信任的访问控制模型TRBAC(trust based access control model).该模型可以提供更加安全、灵活以及细粒度的动态访问授权机制,从而提高授权机制的安全性与可靠性.%Access control is a process which controls users to execute some operations or access some network resources according to the users' identity or attribution. The discretionary access control and mandatory access control are two main access control modes which are broadly used in secure operating systems. Discretionary access control is based on user identity and/or groups and mandatory access control is usually based on sensitivity labels. Neither of these two modes can completely satisfy the requirements of all access control. Discretionary access control is too loose to restrict the propagation of privileges while mandatory access control is too rigid to use flexibly. This paper analyzes current access control models, and extends the RBAC (role based access control) model aiming at its deficiency, and based on which we propose a trust based access control model (TRBAC). The TRBAC model can provide more security, flexible and fine-grained dynamic access control mechanism, and therefore improve both the security and the reliability of authorization mechanism.

  3. Empirical model for the Earth's cosmic ray shadow at 400 KM: prohibited cosmic ray access

    International Nuclear Information System (INIS)

    Humble, J.E.; Smart, D.F.; Shea, M.A.

    1985-01-01

    The possibility of constructing a unit sphere of access that describes the cosmic radiation allowed to an Earth-orbiting spacecraft is discussed. It is found that it is possible to model the occluded portion of the cosmic ray sphere of access as a circular projection with a diameter bounded by the satellite-Earth horizon. Maintaining tangency at the eastern edge of the spacecraft-Earth horizon, this optically occluded area is projected downward by an angle beta which is a function of the magnetic field inclination and cosmic ray arrival direction. This projected plane, corresponding to the forbidden area of cosmic ray access, is bounded by the spacecraft-Earth horizon in easterly directions, and is rotated around the vertical axis by an angle alpha from the eastern direction, where the angle alpha is a function of the offset dipole latitude of the spacecraft

  4. Modeling the Effects of Mortality on Sea Otter Populations

    Science.gov (United States)

    Bodkin, James L.; Ballachey, Brenda E.

    2010-01-01

    Conservation and management of sea otters can benefit from managing the magnitude and sex composition of human related mortality, including harvesting within sustainable levels. Using age and sex-specific reproduction and survival rates from field studies, we created matrix population models representing sea otter populations with growth rates of 1.005, 1.072, and 1.145, corresponding to stable, moderate, and rapid rates of change. In each modeled population, we incrementally imposed additional annual mortality over a 20-year period and calculated average annual rates of change (lambda). Additional mortality was applied to (1) males only, (2) at a 1:1 ratio of male to female, and (3) at a 3:1 ratio of male to female. Dependent pups (age 0-0.5) were excluded from the mortality. Maintaining a stable or slightly increasing population was largely dependent on (1) the magnitude of additional mortality, (2) the underlying rate of change in the population during the period of additional mortality, and (3) the extent that females were included in the additional mortality (due to a polygnous reproductive system where one male may breed with more than one female). In stable populations, additional mortality as high as 2.4 percent was sustainable if limited to males only, but was reduced to 1.2 percent when males and females were removed at ratios of 3:1 or 0.5 percent at ratios of 1:1. In moderate growth populations, additional mortality of 9.8 percent (male-only) and 15.0 percent (3:1 male to female) maximized the sustainable mortality about 3-10 ten-fold over the stable population levels. However, if additional mortality consists of males and females at equal proportions, the sustainable rate is 7.7 percent. In rapid growth populations, maximum sustainable levels of mortality as high as 27.3 percent were achieved when the ratio of additional mortality was 3:1 male to female. Although male-only mortality maximized annual harvest in stable populations, high male biased

  5. Socio economic position in TB prevalence and access to services: results from a population prevalence survey and a facility-based survey in Bangladesh.

    Science.gov (United States)

    Hossain, Shahed; Quaiyum, Mohammad Abdul; Zaman, Khalequ; Banu, Sayera; Husain, Mohammad Ashaque; Islam, Mohammad Akramul; Cooreman, Erwin; Borgdorff, Martien; Lönnroth, Knut; Salim, Abdul Hamid; van Leth, Frank

    2012-01-01

    In Bangladesh DOTS has been provided free of charge since 1993, yet information on access to TB services by different population group is not well documented. The objective of this study was to assess and compare the socio economic position (SEP) of actively detected cases from the community and the cases being routinely detected under National Tuberculosis Control Programme (NTP) in Bangladesh. SEP was assessed by validated asset item for each of the 21,427 households included in the national tuberculosis prevalence survey 2007-2009. A principal component analysis generated household scores and categorized in quartiles. The distribution of 33 actively identified cases was compared with the 240 NTP cases over the identical SEP quartiles to evaluate access to TB services by different groups of the population. The population prevalence of tuberculosis was 5 times higher in the lowest quartiles of population (95.4, 95% CI: 48.0-189.7) to highest quartile population (19.5, 95% CI: 6.9-55.0). Among the 33 cases detected during survey, 25 (75.8%) were from lower two quartiles, and the rest 8 (24.3%) were from upper two quartiles. Among TB cases detected passively under NTP, more than half of them 137 (57.1%) were from uppermost two quartiles, 98 (41%) from the second quartile, and 5 (2%) in the lowest quartile of the population. This distribution is not affected when adjusted for other factors or interactions among them. The findings indicate that despite availability free of charge, DOTS is not equally accessed by the poorer sections of the population. However, these figures should be interpreted with caution since there is a need for additional studies that assess in-depth poverty indicators and its determinants in relation to access of the TB services provided in Bangladesh.

  6. Moving across the border: Modeling migratory bat populations

    Science.gov (United States)

    Ruscena, Wiederholt; López-Hoffman, Laura; Cline, Jon; Medellin, Rodrigo; Cryan, Paul M.; Russell, Amy; McCracken, Gary; Diffendorfer, Jay; Semmens, Darius J.

    2013-01-01

    The migration of animals across long distances and between multiple habitats presents a major challenge for conservation. For the migratory Mexican free-tailed bat (Tadarida brasiliensis mexicana), these challenges include identifying and protecting migratory routes and critical roosts in two countries, the United States and Mexico. Knowledge and conservation of bat migratory routes is critical in the face of increasing threats from climate change and wind turbines that might decrease migratory survival. We employ a new modeling approach for bat migration, network modeling, to simulate migratory routes between winter habitat in southern Mexico and summer breeding habitat in northern Mexico and the southwestern United States. We use the model to identify key migratory routes and the roosts of greatest conservation value to the overall population. We measure roost importance by the degree to which the overall bat population declined when the roost was removed from the model. The major migratory routes—those with the greatest number of migrants—were between winter habitat in southern Mexico and summer breeding roosts in Texas and the northern Mexican states of Sonora and Nuevo Leon. The summer breeding roosts in Texas, Sonora, and Nuevo Leon were the most important for maintaining population numbers and network structure – these are also the largest roosts. This modeling approach contributes to conservation efforts by identifying the most influential areas for bat populations, and can be used as a tool to improve our understanding of bat migration for other species. We anticipate this approach will help direct coordination of habitat protection across borders.

  7. An exploration of multilevel modeling for estimating access to drinking-water and sanitation.

    Science.gov (United States)

    Wolf, Jennyfer; Bonjour, Sophie; Prüss-Ustün, Annette

    2013-03-01

    Monitoring progress towards the targets for access to safe drinking-water and sanitation under the Millennium Development Goals (MDG) requires reliable estimates and indicators. We analyzed trends and reviewed current indicators used for those targets. We developed continuous time series for 1990 to 2015 for access to improved drinking-water sources and improved sanitation facilities by country using multilevel modeling (MLM). We show that MLM is a reliable and transparent tool with many advantages over alternative approaches to estimate access to facilities. Using current indicators, the MDG target for water would be met, but the target for sanitation missed considerably. The number of people without access to such services is still increasing in certain regions. Striking differences persist between urban and rural areas. Consideration of water quality and different classification of shared sanitation facilities would, however, alter estimates considerably. To achieve improved monitoring we propose: (1) considering the use of MLM as an alternative for estimating access to safe drinking-water and sanitation; (2) completing regular assessments of water quality and supporting the development of national regulatory frameworks as part of capacity development; (3) evaluating health impacts of shared sanitation; (4) using a more equitable presentation of countries' performances in providing improved services.

  8. Modelling of radionuclide transport along the underground access structures of deep geological repositories

    Energy Technology Data Exchange (ETDEWEB)

    Poller, A. [National Cooperative for the Disposal of Radioactive Waste (NAGRA), Wettingen (Switzerland); Smith, P. [SAM Switzerland GmbH, Zuerich (Switzerland); Mayer, G.; Hayek, M. [AF-Consult Switzerland AG, Baden (Switzerland)

    2014-08-15

    The arrangement and sealing of the access routes to a deep geological repository for radioactive waste should ensure that any radionuclide release from the emplacement rooms during the post closure phase does not by-pass the geological barriers of the repository system to a significant extent. The base case of the present study, where realistic values for the hydraulic properties of the seals and the associated excavation damage zones were assumed, assesses to what extent this is actually the case for different layout variants (ramp and shaft access and shaft access only). Furthermore, as a test of robustness of system performance against uncertainties related to such seals and the associated excavation damage zones, the present study also considers a broad spectrum of calculation cases including the hypothetical possibility that the seals perform much more poorly than expected and to check whether, consequently, the repository tunnel system and the access structures may provide significant release pathways. The study considers a generic repository system for high-level waste (HLW repository) and for low- and intermediate-level waste (L/ILW repository), both with Opalinus Clay as the host rock. It also considers the alternative possibilities of a ramp or a shaft as the access route for material transport (waste packages, etc.) to the underground facilities. Additional shafts, e.g. for the transport of persons and for ventilation, are included in both cases. The overall modelling approach consists of three broad steps: (a) the network of tunnels and access structures is implemented in a flow model, which serves to calculate water flow rates along the tunnels and through the host rock; (b) all relevant transport paths are implemented in a radionuclide release and transport model, the water flow rates being obtained from the preceding flow model calculations; (c) individual effective dose rates arising from the radionuclides released from the considered repository

  9. Power Allocation in Multiple Access Networks: Implementation Aspects via Verhulst and Perron-Frobenius Models

    Directory of Open Access Journals (Sweden)

    Fábio Engel de Camargo

    2012-11-01

    Full Text Available In this work, the Verhulst model and the Perron-Frobenius theorem are applied on the power control problem which is a concern in multiple access communication networks due to the multiple access interference. This paper deals with the performance versus complexity tradeoff of both power control algorithm (PCA, as well as highlights the computational cost aspects regarding the implementability of distributed PCA (DPCA version for both algorithms. As a proof-of-concept the DPCA implementation is carried out deploying a commercial point-floating DSP platform. Numerical results in terms of DSP cycles and computational time as well indicate a feasibility of implementing the PCA-Verhulst model in 2G and 3G cellular systems; b high computational cost for the PCA-Perron-Frobenius model.

  10. Population Synthesis Models for Normal Galaxies with Dusty Disks

    Directory of Open Access Journals (Sweden)

    Kyung-Won Suh

    2003-09-01

    Full Text Available To investigate the SEDs of galaxies considering the dust extinction processes in the galactic disks, we present the population synthesis models for normal galaxies with dusty disks. We use PEGASE (Fioc & Rocca-Volmerange 1997 to model them with standard input parameters for stars and new dust parameters. We find that the model results are strongly dependent on the dust parameters as well as other parameters (e.g. star formation history. We compare the model results with the observations and discuss about the possible explanations. We find that the dust opacity functions derived from studies of asymptotic giant branch stars are useful for modeling a galaxy with a dusty disk.

  11. Modeling coding-sequence evolution within the context of residue solvent accessibility.

    Science.gov (United States)

    Scherrer, Michael P; Meyer, Austin G; Wilke, Claus O

    2012-09-12

    Protein structure mediates site-specific patterns of sequence divergence. In particular, residues in the core of a protein (solvent-inaccessible residues) tend to be more evolutionarily conserved than residues on the surface (solvent-accessible residues). Here, we present a model of sequence evolution that explicitly accounts for the relative solvent accessibility of each residue in a protein. Our model is a variant of the Goldman-Yang 1994 (GY94) model in which all model parameters can be functions of the relative solvent accessibility (RSA) of a residue. We apply this model to a data set comprised of nearly 600 yeast genes, and find that an evolutionary-rate ratio ω that varies linearly with RSA provides a better model fit than an RSA-independent ω or an ω that is estimated separately in individual RSA bins. We further show that the branch length t and the transition-transverion ratio κ also vary with RSA. The RSA-dependent GY94 model performs better than an RSA-dependent Muse-Gaut 1994 (MG94) model in which the synonymous and non-synonymous rates individually are linear functions of RSA. Finally, protein core size affects the slope of the linear relationship between ω and RSA, and gene expression level affects both the intercept and the slope. Structure-aware models of sequence evolution provide a significantly better fit than traditional models that neglect structure. The linear relationship between ω and RSA implies that genes are better characterized by their ω slope and intercept than by just their mean ω.

  12. Modeling coding-sequence evolution within the context of residue solvent accessibility

    Directory of Open Access Journals (Sweden)

    Scherrer Michael P

    2012-09-01

    Full Text Available Abstract Background Protein structure mediates site-specific patterns of sequence divergence. In particular, residues in the core of a protein (solvent-inaccessible residues tend to be more evolutionarily conserved than residues on the surface (solvent-accessible residues. Results Here, we present a model of sequence evolution that explicitly accounts for the relative solvent accessibility of each residue in a protein. Our model is a variant of the Goldman-Yang 1994 (GY94 model in which all model parameters can be functions of the relative solvent accessibility (RSA of a residue. We apply this model to a data set comprised of nearly 600 yeast genes, and find that an evolutionary-rate ratio ω that varies linearly with RSA provides a better model fit than an RSA-independent ω or an ω that is estimated separately in individual RSA bins. We further show that the branch length t and the transition-transverion ratio κ also vary with RSA. The RSA-dependent GY94 model performs better than an RSA-dependent Muse-Gaut 1994 (MG94 model in which the synonymous and non-synonymous rates individually are linear functions of RSA. Finally, protein core size affects the slope of the linear relationship between ω and RSA, and gene expression level affects both the intercept and the slope. Conclusions Structure-aware models of sequence evolution provide a significantly better fit than traditional models that neglect structure. The linear relationship between ω and RSA implies that genes are better characterized by their ω slope and intercept than by just their mean ω.

  13. A stage-based model of manatee population dynamics

    Science.gov (United States)

    Runge, M.C.; Langtimm, C.A.; Kendall, W.L.

    2004-01-01

    A stage-structured population model for the Florida manatee (Trichechus manatus latirostris) was developed that explicitly incorporates uncertainty in parameter estimates. The growth rates calculated with this model reflect the status of the regional populations over the most recent 10-yr period. The Northwest and Upper St. Johns River regions have growth rates (8) of 1.037 (95% interval, 1.016?1.056) and 1.062 (1.037?1.081), respectively. The Southwest region has a growth rate of 0.989 (0.946?1.024), suggesting this population has been declining at about 1.1% per year. The estimated growth rate in the Atlantic region is 1.010 (0.988?1.029), but there is some uncertainty about whether adult survival rates have been constant over the last 10 yr; using the mean survival rates from the most recent 5-yr period, the estimated growth rate in this region is 0.970 (0.938?0.998). Elasticity analysis indicates that the most effective management actions should seek to increase adult survival rates. Decomposition of the uncertainty in the growth rates indicates that uncertainty about population status can best be reduced through increased monitoring of adult survival rate.

  14. Integration of manatee life-history data and population modeling

    Science.gov (United States)

    Eberhardt, L.L.; O'Shea, Thomas J.; O'Shea, Thomas J.; Ackerman, B.B.; Percival, H. Franklin

    1995-01-01

    Aerial counts and the number of deaths have been a major focus of attention in attempts to understand the population status of the Florida manatee (Trichechus manatus latirostris). Uncertainties associated with these data have made interpretation difficult. However, knowledge of manatee life-history attributes increased and now permits the development of a population model. We describe a provisional model based on the classical approach of Lotka. Parameters in the model are based on data from'other papers in this volume and draw primarily on observations from the Crystal River, Blue Spring, and Adantic Coast areas. The model estimates X (the finite rate ofincrease) at each study area, and application ofthe delta method provides estimates of variance components and partial derivatives ofX with respectto key input parameters (reproduction, adult survival, and early survival). In some study areas, only approximations of some parameters are available. Estimates of X and coefficients of variation (in parentheses) of manatees were 1.07 (0.009) in the Crystal River, 1.06 (0.012) at Blue Spring, and 1.01 (0.012) on the Atlantic Coast. Changing adult survival has a major effect on X. Early-age survival has the smallest effect. Bootstrap comparisons of population growth estimates from trend counts in the Crystal River and at Blue Spring and the reproduction and survival data suggest that the higher, observed rates from counts are probably not due to chance. Bootstrapping for variance estimates based on reproduction and survival data from manatees at Blue Spring and in the Crystal River provided estimates of X, adult survival, and rates of reproduction that were similar to those obtained by other methods. Our estimates are preliminary and suggestimprovements for future data collection and analysis. However, results support efforts to reduce mortality as the most effective means to promote the increased growth necessary for the eventual recovery of the Florida manatee

  15. Development and Testing of a Conceptual Model Regarding Men’s Access to Health Care

    Science.gov (United States)

    Leone, James E.; Rovito, Michael J.; Mullin, Elizabeth M.; Mohammed, Shan D.; Lee, Christina S.

    2016-01-01

    Epidemiologic data suggest men often experience excessive morbidity and early mortality, possibly compromising family and community health over the lifespan. Moreover, the negative financial/economic consequences affected by poor male health outcomes also has been of great concern in the United States and abroad. Early and consistent access to preventative health care may improve health outcomes; however, men are far less likely to access these services. The purpose of this study was to understand what factors preclude men from accessing health care. We surveyed 485 participants using a 58-item online survey built from a conceptual model previously developed by the researchers using hegemonic masculinity theory, the theory of normative contentment, and the health belief model. For men, three items significantly (ps masculine ideals may play a primary role in how men access preventative health care. Future programming targeting males should consider barriers and plan programs that are gender-sensitive in addition to being gender-specific. Clinical implications are discussed. PMID:27698256

  16. Model of traffic access mode and railway station choice of suburban railway system in Slovenia

    Directory of Open Access Journals (Sweden)

    Gregor RAK

    2014-12-01

    Full Text Available This article presents the establishment of a model of understanding the access mode and railway station choice of Slovenian passengers. Therefore, a model has been designed to predict the determination of existing decision making preferences of railway users about the access mode and railway station choice with a stated preference survey and face to face method. The target group in the survey were railway passengers in the suburban environment that use the rail for work and school purposes. The total number of respondents was 412. The survey showed that most passengers access the railway station with car (60,2%, by foot (26,2%, with public transport (bus – 8,3% and with bike (5,3%. Average distance to the station is 4,9 km, average time of access is 10,5 min. Upon exit most passengers walk to the final destination (84,5%, use the public transport (bus – 14,1%, car (1,2% or bike (0,2%. Average time from exit of the train to final destination is 13,1 min, average distance is 1,58 km.

  17. Evaluating models of population process in a threatened population of Steller’s eiders: A retrospective approach

    Science.gov (United States)

    Dunham, Kylee; Grand, James B.

    2016-10-11

    The Alaskan breeding population of Steller’s eiders (Polysticta stelleri) was listed as threatened under the Endangered Species Act in 1997 in response to perceived declines in abundance throughout their breeding and nesting range. Aerial surveys suggest the breeding population is small and highly variable in number, with zero birds counted in 5 of the last 25 years. Research was conducted to evaluate competing population process models of Alaskan-breeding Steller’s eiders through comparison of model projections to aerial survey data. To evaluate model efficacy and estimate demographic parameters, a Bayesian state-space modeling framework was used and each model was fit to counts from the annual aerial surveys, using sequential importance sampling and resampling. The results strongly support that the Alaskan breeding population experiences population level nonbreeding events and is open to exchange with the larger Russian-Pacific breeding population. Current recovery criteria for the Alaskan breeding population rely heavily on the ability to estimate population viability. The results of this investigation provide an informative model of the population process that can be used to examine future population states and assess the population in terms of the current recovery and reclassification criteria.

  18. Modeling population dynamics of mitochondria in mammalian cells

    Science.gov (United States)

    Kornick, Kellianne; Das, Moumita

    Mitochondria are organelles located inside eukaryotic cells and are essential for several key cellular processes such as energy (ATP) production, cell signaling, differentiation, and apoptosis. All organisms are believed to have low levels of variation in mitochondrial DNA (mtDNA), and alterations in mtDNA are connected to a range of human health conditions, including epilepsy, heart failure, Parkinsons disease, diabetes, and multiple sclerosis. Therefore, understanding how changes in mtDNA accumulate over time and are correlated to changes in mitochondrial function and cell properties can have a profound impact on our understanding of cell physiology and the origins of some diseases. Motivated by this, we develop and study a mathematical model to determine which cellular parameters have the largest impact on mtDNA population dynamics. The model consists of coupled ODEs to describe subpopulations of healthy and dysfunctional mitochondria subject to mitochondrial fission, fusion, autophagy, and mutation. We study the time evolution and stability of each sub-population under specific selection biases and pressures by tuning specific terms in our model. Our results may provide insights into how sub-populations of mitochondria survive and evolve under different selection pressures. This work was supported by a Grant from the Moore Foundation.

  19. Simulation models in population breast cancer screening: A systematic review.

    Science.gov (United States)

    Koleva-Kolarova, Rositsa G; Zhan, Zhuozhao; Greuter, Marcel J W; Feenstra, Talitha L; De Bock, Geertruida H

    2015-08-01

    The aim of this review was to critically evaluate published simulation models for breast cancer screening of the general population and provide a direction for future modeling. A systematic literature search was performed to identify simulation models with more than one application. A framework for qualitative assessment which incorporated model type; input parameters; modeling approach, transparency of input data sources/assumptions, sensitivity analyses and risk of bias; validation, and outcomes was developed. Predicted mortality reduction (MR) and cost-effectiveness (CE) were compared to estimates from meta-analyses of randomized control trials (RCTs) and acceptability thresholds. Seven original simulation models were distinguished, all sharing common input parameters. The modeling approach was based on tumor progression (except one model) with internal and cross validation of the resulting models, but without any external validation. Differences in lead times for invasive or non-invasive tumors, and the option for cancers not to progress were not explicitly modeled. The models tended to overestimate the MR (11-24%) due to screening as compared to optimal RCTs 10% (95% CI - 2-21%) MR. Only recently, potential harms due to regular breast cancer screening were reported. Most scenarios resulted in acceptable cost-effectiveness estimates given current thresholds. The selected models have been repeatedly applied in various settings to inform decision making and the critical analysis revealed high risk of bias in their outcomes. Given the importance of the models, there is a need for externally validated models which use systematical evidence for input data to allow for more critical evaluation of breast cancer screening. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. The U.S. Rural Population and Scheduled Intercity Transportation in 2010 : A Five-Year Decline in Transportation Access.

    Science.gov (United States)

    2011-02-01

    Between 2005 and 2010, 3.5 million rural residents lost access to scheduled intercity transportation, increasing the percent of rural residents without access to intercity transportation from 7 to 11 percent. In 2005, 5.4 million rural residents lack...

  1. Open Access Papers Have a Greater Citation Advantage in the Author-Pays Model

    Directory of Open Access Journals (Sweden)

    Elaine Sullo

    2016-03-01

    Full Text Available Objective – To investigate the citation performance of open access (OA and toll access (TA papers published in author-pays open access journals. Design – Longitudinal citation analysis. Setting – Publications in Springer and Elsevier’s author-pays open access journals. Subjects – 633 journals published using the author-pays model. This model encompasses both journals where the article processing charge (APC is required and journals in which authors can request open access and voluntarily pay APCs for accepted manuscripts. Methods – The authors identified APC funded journals (journals funded by mandatory author processing charges as well as those where authors voluntarily paid a fee in order to have their articles openly accessible from both Springer and Elsevier, and analyzed papers published in these journals from 2007 to 2011. The authors excluded journals that adopted the APC model later than 2007. To identify Springer titles, the authors created a search strategy to identify open access articles in SpringerLink. A total of 576 journals were identified and double checked in the Sherpa-Romeo database (a database of copyright and open access self-archiving policies of academic journals to verify their open access policies. The authors then downloaded the journal content using SpringerLink, and using Springer Author-Mapper, separated out the open access articles from the toll access articles. In order to identify the Elsevier APC funded journals, the authors referred to “Open Access Journal Directory: A-Z,” which contained 35 OA journals (p. 584. Once the authors consulted “Sponsored articles” issued by Elsevier and verified titles in Sherpa-Romeo, they identified 57 journals that fit the “author-pays” model. The bibliographic information was downloaded and OA articles were separated from TA articles. The authors confirmed that all journals were indeed OA publications by downloading the full-text from off-campus locations

  2. Reference man models based on normal data from human populations

    International Nuclear Information System (INIS)

    Tanaka, Gi-ichiro; Kawamura, Hisao

    2000-01-01

    Quantitative description of the physical, and metabolic parameters of the human body is the very basic for internal dosimetry. Compilation of anatomical and other types of data Asian populations for internal (and external) dosimetry is of grate significance because of the potential spread of nuclear energy use in the Asian region and the major contribution of the region to the world population (about 58%). It has been observed that some differences exist for habitat, race, body sizes and pattern of food consumption. In the early stage of revision of ICRP Reference man by the Task Group, Characteristics of the human body of non-European populations received considerable attention as well as those of the European populations of different sexes and ages. In this context, an IAEA-RCA Co-ordinated Research Program on Compilation of Anatomical, Physiological and Metabolic Characteristics for a Reference Asian Man endorsed. In later stages of reference Man revision, anatomical data for Asians was discusses together with those of European populations, presumably due to ICRP's decision of unanimous use of the Reference Man for radiation protection. Reference man models for adults and 15, 10, 5, 1, 0 year-old males and females of Asian populations were developed for use in internal and external dosimetry. Based on the concept of ICRP Reference Man (Publication 23), the reference values were derived from the normal organ mass data for Japanese and statistical data on the physique and nutrition of Japanese and Chinese. Also incorporated were variations in physical measurements, as observed in the above mentioned IAEA-RCA Co-ordinated Research Program. The work was partly carried out within the activities of the ICRP Task Group on Reference Man. The weight of the skeleton was adjusted following the revised values in Publication 70. This paper will report basic shared and non-shared characteristics of Reference Man' for Asians and ICRP Reference Man. (author)

  3. The prediction of the cavitation phenomena including population balance modeling

    Science.gov (United States)

    Bannari, Rachid; Hliwa, Ghizlane Zineb; Bannari, Abdelfettah; Belghiti, Mly Taib

    2017-07-01

    Cavitation is the principal reason behind the behavior's modification of the hydraulic turbines. However, the experimental observations can not be appropriate to all cases due to the limitations in the measurement techniques. The mathematical models which have been implemented, use the mixture multiphase frame. As well as, most of the published work is limited by considering a constant bubble size distribution. However, this assumption is not realist. The aim of this article is the implementation and the use of a non-homogeneous multiphase model which solve two phases transport equation. The evolution of bubble size is considered by the population balance equation. This study is based on the eulerian-eulerian model, associated to the cavitation model. All the inter-phase forces such as drag, lift and virtual mass are used.

  4. Eulerian Multiphase Population Balance Model of Atomizing, Swirling Flows

    Directory of Open Access Journals (Sweden)

    Narayana P. Rayapati

    2011-06-01

    Full Text Available An Eulerian/Eulerian multiphase flow model coupled with a population balance model is used as the basis for numerical simulation of atomization in swirling flows. The objective of this exercise is to develop a methodology capable of predicting the local point-wise drop size distribution in a spray, such as would be measured by the Phase Doppler Particle Analyzer (PDA. Model predictions are compared to experimental measurements of particle size distributions in an air-blast atomizer spray to demonstrate good qualitative and quantitative agreement. It is observed that the dependence of velocity on drop size inherent in a multiphase description of the drop cloud appears necessary to capture some features of the experimental data. Using this model, we demonstrate the relative contributions of secondary atomization and transport to the variation observed in the downstream spray drop size distribution.

  5. Richards-like two species population dynamics model.

    Science.gov (United States)

    Ribeiro, Fabiano; Cabella, Brenno Caetano Troca; Martinez, Alexandre Souto

    2014-12-01

    The two-species population dynamics model is the simplest paradigm of inter- and intra-species interaction. Here, we present a generalized Lotka-Volterra model with intraspecific competition, which retrieves as particular cases, some well-known models. The generalization parameter is related to the species habitat dimensionality and their interaction range. Contrary to standard models, the species coupling parameters are general, not restricted to non-negative values. Therefore, they may represent different ecological regimes, which are derived from the asymptotic solution stability analysis and are represented in a phase diagram. In this diagram, we have identified a forbidden region in the mutualism regime, and a survival/extinction transition with dependence on initial conditions for the competition regime. Also, we shed light on two types of predation and competition: weak, if there are species coexistence, or strong, if at least one species is extinguished.

  6. Differential access to digital communication technology: association with health and health survey recruitment within an African-American underserviced urban population.

    Science.gov (United States)

    Schneider, John; Makelarski, Jennifer A; Van Haitsma, Martha; Lipton, Rebecca B; Abramsohn, Emily; Lauderdale, Diane S; Lindau, Stacy Tessler

    2011-06-01

    Digital communication technologies (DCT), such as cell phones and the internet, have begun to replace more traditional technologies even in technology-poor communities. We characterized access to DCT in an underserved urban population and whether access is associated with health and study participation. A general probability community sample and a purposive high-turnover housing sample were recruited and re-interviewed after 3 months. Selected characteristics were compared by sample type and retention. Associations between DCT access and self-reported health were examined using multivariable logistic regression. Of 363 eligible individuals, 184 (general community = 119; high-turnover housing = 65) completed the baseline survey. Eighty-four percent of respondents had a cell phone and 62% had ever texted. Ever use of the internet was high (69%) overall, but frequency and years of internet use were higher in the general community sample. Self-reported fair or poor health was more common for residents of cell phone-only households and those with less frequent internet use. Technology use was similar for those retained and not retained. Overall, access to DCT was high in this underserved urban population but varied by sample type. Health varied significantly by DCT use, but study retention did not. These data have implications for incorporating DCT into health-related research in urban populations.

  7. An access-technology agnostic delivery model for ICT4D services

    CSIR Research Space (South Africa)

    Herselman, M

    2012-02-01

    Full Text Available systems outlined by Bieber, Mcfall, Rice, and Gurstein (2007). Their deliberations, however, do not address the issue of access-technology agnostic delivery of information. Furthermore, many of the proposed content distribution models involved a single... be implemented. The ?Black Box Testing Technique? (Krichen & Tripakis, 2004) was adopted; this technique hides the complexities of the system components and only focuses on the system functionality as viewed from the end- user perspective in accordance...

  8. Roles of Solvent Accessibility and Gene Expression in Modeling Protein Sequence Evolution

    OpenAIRE

    Kuangyu Wang; Shuhui Yu; Xiang Ji; Clemens Lakner; Alexander Griffing; Jeffrey L. Thorne

    2015-01-01

    Models of protein evolution tend to ignore functional constraints, although structural constraints are sometimes incorporated. Here we propose a probabilistic framework for codon substitution that evaluates joint effects of relative solvent accessibility (RSA), a structural constraint; and gene expression, a functional constraint. First, we explore the relationship between RSA and codon usage at the genomic scale as well as at the individual gene scale. Motivated by these results, we construc...

  9. How to implement ‘access to medicine’ AND enhance economic performance:business model options for global access

    OpenAIRE

    Peukert, J. (Jürgen); Fuggenthaler, T. (Thomas)

    2009-01-01

    Access to medicine’ or ‘global access’ is at the core heart of corporate responsibility for pharmaceutical companies. Corporate responsibility, however, is not restricted to a philanthropic dimension (such as donations), which is often referred to as corporate citizenship. It also includes corporate social responsibility (in the narrower sense) and corporate governance and thereby paves the way for linking corporate citizenship – “to be a good corporate citizen and contribute to the communit...

  10. A Collective Study on Modeling and Simulation of Resistive Random Access Memory

    Science.gov (United States)

    Panda, Debashis; Sahu, Paritosh Piyush; Tseng, Tseung Yuen

    2018-01-01

    In this work, we provide a comprehensive discussion on the various models proposed for the design and description of resistive random access memory (RRAM), being a nascent technology is heavily reliant on accurate models to develop efficient working designs and standardize its implementation across devices. This review provides detailed information regarding the various physical methodologies considered for developing models for RRAM devices. It covers all the important models reported till now and elucidates their features and limitations. Various additional effects and anomalies arising from memristive system have been addressed, and the solutions provided by the models to these problems have been shown as well. All the fundamental concepts of RRAM model development such as device operation, switching dynamics, and current-voltage relationships are covered in detail in this work. Popular models proposed by Chua, HP Labs, Yakopcic, TEAM, Stanford/ASU, Ielmini, Berco-Tseng, and many others have been compared and analyzed extensively on various parameters. The working and implementations of the window functions like Joglekar, Biolek, Prodromakis, etc. has been presented and compared as well. New well-defined modeling concepts have been discussed which increase the applicability and accuracy of the models. The use of these concepts brings forth several improvements in the existing models, which have been enumerated in this work. Following the template presented, highly accurate models would be developed which will vastly help future model developers and the modeling community.

  11. Distinguishing Antimicrobial Models with Different Resistance Mechanisms via Population Pharmacodynamic Modeling.

    Directory of Open Access Journals (Sweden)

    Matthieu Jacobs

    2016-03-01

    Full Text Available Semi-mechanistic pharmacokinetic-pharmacodynamic (PK-PD modeling is increasingly used for antimicrobial drug development and optimization of dosage regimens, but systematic simulation-estimation studies to distinguish between competing PD models are lacking. This study compared the ability of static and dynamic in vitro infection models to distinguish between models with different resistance mechanisms and support accurate and precise parameter estimation. Monte Carlo simulations (MCS were performed for models with one susceptible bacterial population without (M1 or with a resting stage (M2, a one population model with adaptive resistance (M5, models with pre-existing susceptible and resistant populations without (M3 or with (M4 inter-conversion, and a model with two pre-existing populations with adaptive resistance (M6. For each model, 200 datasets of the total bacterial population were simulated over 24h using static antibiotic concentrations (256-fold concentration range or over 48h under dynamic conditions (dosing every 12h; elimination half-life: 1h. Twelve-hundred random datasets (each containing 20 curves for static or four curves for dynamic conditions were generated by bootstrapping. Each dataset was estimated by all six models via population PD modeling to compare bias and precision. For M1 and M3, most parameter estimates were unbiased (<10% and had good imprecision (<30%. However, parameters for adaptive resistance and inter-conversion for M2, M4, M5 and M6 had poor bias and large imprecision under static and dynamic conditions. For datasets that only contained viable counts of the total population, common statistical criteria and diagnostic plots did not support sound identification of the true resistance mechanism. Therefore, it seems advisable to quantify resistant bacteria and characterize their MICs and resistance mechanisms to support extended simulations and translate from in vitro experiments to animal infection models and

  12. INTEGRATIVE METHOD OF TEACHING INFORMATION MODELING IN PRACTICAL HEALTH SERVICE BASED ON MICROSOFT ACCESS QUERIES

    Directory of Open Access Journals (Sweden)

    Svetlana A. Firsova

    2016-06-01

    Full Text Available Introduction: this article explores the pedagogical technology employed to teach medical students foundations of work with MICROSOFT ACCESS databases. The above technology is based on integrative approach to the information modeling in public health practice, drawing upon basic didactic concepts that pertain to objects and tools databases created in MICROSOFT ACCESS. The article examines successive steps in teaching the topic “Queries in MICROSOFT ACCESS” – from simple queries to complex ones. The main attention is paid to such components of methodological system, as the principles and teaching methods classified according to the degree of learners’ active cognitive activity. The most interesting is the diagram of the relationship of learning principles, teaching methods and specific types of requests. Materials and Methods: the authors used comparative analysis of literature, syllabi, curricula in medical informatics taught at leading medical universities in Russia. Results: the original technique of training in putting queries with databases of MICROSOFT ACCESS is presented for analysis of information models in practical health care. Discussion and Conclusions: it is argued that the proposed pedagogical technology will significantly improve the effectiveness of teaching the course “Medical Informatics”, that includes development and application of models to simulate the operation of certain facilities and services of the health system which, in turn, increases the level of information culture of practitioners.

  13. A Model-driven Role-based Access Control for SQL Databases

    Directory of Open Access Journals (Sweden)

    Raimundas Matulevičius

    2015-07-01

    Full Text Available Nowadays security has become an important aspect in information systems engineering. A mainstream method for information system security is Role-based Access Control (RBAC, which restricts system access to authorised users. While the benefits of RBAC are widely acknowledged, the implementation and administration of RBAC policies remains a human intensive activity, typically postponed until the implementation and maintenance phases of system development. This deferred security engineering approach makes it difficult for security requirements to be accurately captured and for the system’s implementation to be kept aligned with these requirements as the system evolves. In this paper we propose a model-driven approach to manage SQL database access under the RBAC paradigm. The starting point of the approach is an RBAC model captured in SecureUML. This model is automatically translated to Oracle Database views and instead-of triggers code, which implements the security constraints. The approach has been fully instrumented as a prototype and its effectiveness has been validated by means of a case study.

  14. QoS Modeling for End-to-End Performance Evaluation over Networks with Wireless Access

    Directory of Open Access Journals (Sweden)

    Gómez Gerardo

    2010-01-01

    Full Text Available This paper presents an end-to-end Quality of Service (QoS model for assessing the performance of data services over networks with wireless access. The proposed model deals with performance degradation across protocol layers using a bottom-up strategy, starting with the physical layer and moving on up to the application layer. This approach makes it possible to analytically assess performance at different layers, thereby facilitating a possible end-to-end optimization process. As a representative case, a scenario where a set of mobile terminals connected to a streaming server through an IP access node has been studied. UDP, TCP, and the new TCP-Friendly Rate Control (TFRC protocols were analyzed at the transport layer. The radio interface consisted of a variable-rate multiuser and multichannel subsystem, including retransmissions and adaptive modulation and coding. The proposed analytical QoS model was validated on a real-time emulator of an end-to-end network with wireless access and proved to be very useful for the purposes of service performance estimation and optimization.

  15. Population Structure in the Model Grass Brachypodium distachyon Is Highly Correlated with Flowering Differences across Broad Geographic Areas

    Directory of Open Access Journals (Sweden)

    Ludmila Tyler

    2016-07-01

    Full Text Available The small, annual grass (L. Beauv., a close relative of wheat ( L. and barley ( L., is a powerful model system for cereals and bioenergy grasses. Genome-wide association studies (GWAS of natural variation can elucidate the genetic basis of complex traits but have been so far limited in by the lack of large numbers of well-characterized and sufficiently diverse accessions. Here, we report on genotyping-by-sequencing (GBS of 84 , seven , and three accessions with diverse geographic origins including Albania, Armenia, Georgia, Italy, Spain, and Turkey. Over 90,000 high-quality single-nucleotide polymorphisms (SNPs distributed across the Bd21 reference genome were identified. Our results confirm the hybrid nature of the genome, which appears as a mosaic of -like and -like sequences. Analysis of more than 50,000 SNPs for the accessions revealed three distinct, genetically defined populations. Surprisingly, these genomic profiles are associated with differences in flowering time rather than with broad geographic origin. High levels of differentiation in loci associated with floral development support the differences in flowering phenology between populations. Genome-wide association studies combining genotypic and phenotypic data also suggest the presence of one or more photoperiodism, circadian clock, and vernalization genes in loci associated with flowering time variation within populations. Our characterization elucidates genes underlying population differences, expands the germplasm resources available for , and illustrates the feasibility and limitations of GWAS in this model grass.

  16. Intraosseous vascular access through the anterior mandible--a cadaver model pilot study.

    Directory of Open Access Journals (Sweden)

    Christin Goldschalt

    Full Text Available BACKGROUND: Several insertion sites have been described for intraosseous puncture in cases of emergencies when a conventional vascular access cannot be established. This pilot study has been designed to evaluate the feasibility of the mandibular bone for the use of an intraosseous vascular access in a cadaver model. METHODOLOGY/PRINCIPAL FINDINGS: 17 dentistry and 16 medical students participating in a voluntary course received a short introduction into the method and subsequently used the battery powered EZ-IO system with a 15 mm cannula for a puncture of the anterior mandible in 33 cadavers. The time needed to perform each procedure was evaluated. India ink was injected into the accesses and during the anatomy course cadavers were dissected to retrace the success or failure of the puncture. Dental students needed 25.5±18.9(mean±standard deviations and medical students 33±20.4 s for the procedure (p = 0.18. Floor of mouth extravasation occurred in both groups in 3 cases. Success rates were 82 and 75% (p = 0.93. CONCLUSIONS/SIGNIFICANCE: Despite floor of mouth extravasation of injected fluid into a mandibular intraosseous access might severely complicate this procedure, the anterior mandible may be helpful as an alternative to other intraosseous and intravenous insertion sites when these are not available in medical emergencies.

  17. Modelling multi-pulse population dynamics from ultrafast spectroscopy.

    Directory of Open Access Journals (Sweden)

    Luuk J G W van Wilderen

    2011-03-01

    Full Text Available Current advanced laser, optics and electronics technology allows sensitive recording of molecular dynamics, from single resonance to multi-colour and multi-pulse experiments. Extracting the occurring (bio- physical relevant pathways via global analysis of experimental data requires a systematic investigation of connectivity schemes. Here we present a Matlab-based toolbox for this purpose. The toolbox has a graphical user interface which facilitates the application of different reaction models to the data to generate the coupled differential equations. Any time-dependent dataset can be analysed to extract time-independent correlations of the observables by using gradient or direct search methods. Specific capabilities (i.e. chirp and instrument response function for the analysis of ultrafast pump-probe spectroscopic data are included. The inclusion of an extra pulse that interacts with a transient phase can help to disentangle complex interdependent pathways. The modelling of pathways is therefore extended by new theory (which is included in the toolbox that describes the finite bleach (orientation effect of single and multiple intense polarised femtosecond pulses on an ensemble of randomly oriented particles in the presence of population decay. For instance, the generally assumed flat-top multimode beam profile is adapted to a more realistic Gaussian shape, exposing the need for several corrections for accurate anisotropy measurements. In addition, the (selective excitation (photoselection and anisotropy of populations that interact with single or multiple intense polarised laser pulses is demonstrated as function of power density and beam profile. Using example values of real world experiments it is calculated to what extent this effectively orients the ensemble of particles. Finally, the implementation includes the interaction with multiple pulses in addition to depth averaging in optically dense samples. In summary, we show that mathematical

  18. Modelling multi-pulse population dynamics from ultrafast spectroscopy.

    Science.gov (United States)

    van Wilderen, Luuk J G W; Lincoln, Craig N; van Thor, Jasper J

    2011-03-21

    Current advanced laser, optics and electronics technology allows sensitive recording of molecular dynamics, from single resonance to multi-colour and multi-pulse experiments. Extracting the occurring (bio-) physical relevant pathways via global analysis of experimental data requires a systematic investigation of connectivity schemes. Here we present a Matlab-based toolbox for this purpose. The toolbox has a graphical user interface which facilitates the application of different reaction models to the data to generate the coupled differential equations. Any time-dependent dataset can be analysed to extract time-independent correlations of the observables by using gradient or direct search methods. Specific capabilities (i.e. chirp and instrument response function) for the analysis of ultrafast pump-probe spectroscopic data are included. The inclusion of an extra pulse that interacts with a transient phase can help to disentangle complex interdependent pathways. The modelling of pathways is therefore extended by new theory (which is included in the toolbox) that describes the finite bleach (orientation) effect of single and multiple intense polarised femtosecond pulses on an ensemble of randomly oriented particles in the presence of population decay. For instance, the generally assumed flat-top multimode beam profile is adapted to a more realistic Gaussian shape, exposing the need for several corrections for accurate anisotropy measurements. In addition, the (selective) excitation (photoselection) and anisotropy of populations that interact with single or multiple intense polarised laser pulses is demonstrated as function of power density and beam profile. Using example values of real world experiments it is calculated to what extent this effectively orients the ensemble of particles. Finally, the implementation includes the interaction with multiple pulses in addition to depth averaging in optically dense samples. In summary, we show that mathematical modelling is

  19. Geospatial Modeling of Asthma Population in Relation to Air Pollution

    Science.gov (United States)

    Kethireddy, Swatantra R.; Tchounwou, Paul B.; Young, John H.; Luvall, Jeffrey C.; Alhamdan, Mohammad

    2013-01-01

    Current observations indicate that asthma is growing every year in the United States, specific reasons for this are not well understood. This study stems from an ongoing research effort to investigate the spatio-temporal behavior of asthma and its relatedness to air pollution. The association between environmental variables such as air quality and asthma related health issues over Mississippi State are investigated using Geographic Information Systems (GIS) tools and applications. Health data concerning asthma obtained from Mississippi State Department of Health (MSDH) for 9-year period of 2003-2011, and data of air pollutant concentrations (PM2.5) collected from USEPA web resources, and are analyzed geospatially to establish the impacts of air quality on human health specifically related to asthma. Disease mapping using geospatial techniques provides valuable insights into the spatial nature, variability, and association of asthma to air pollution. Asthma patient hospitalization data of Mississippi has been analyzed and mapped using quantitative Choropleth techniques in ArcGIS. Patients have been geocoded to their respective zip codes. Potential air pollutant sources of Interstate highways, Industries, and other land use data have been integrated in common geospatial platform to understand their adverse contribution on human health. Existing hospitals and emergency clinics are being injected into analysis to further understand their proximity and easy access to patient locations. At the current level of analysis and understanding, spatial distribution of Asthma is observed in the populations of Zip code regions in gulf coast, along the interstates of south, and in counties of Northeast Mississippi. It is also found that asthma is prevalent in most of the urban population. This GIS based project would be useful to make health risk assessment and provide information support to the administrators and decision makers for establishing satellite clinics in future.

  20. Prediction Model for Gastric Cancer Incidence in Korean Population.

    Directory of Open Access Journals (Sweden)

    Bang Wool Eom

    Full Text Available Predicting high risk groups for gastric cancer and motivating these groups to receive regular checkups is required for the early detection of gastric cancer. The aim of this study is was to develop a prediction model for gastric cancer incidence based on a large population-based cohort in Korea.Based on the National Health Insurance Corporation data, we analyzed 10 major risk factors for gastric cancer. The Cox proportional hazards model was used to develop gender specific prediction models for gastric cancer development, and the performance of the developed model in terms of discrimination and calibration was also validated using an independent cohort. Discrimination ability was evaluated using Harrell's C-statistics, and the calibration was evaluated using a calibration plot and slope.During a median of 11.4 years of follow-up, 19,465 (1.4% and 5,579 (0.7% newly developed gastric cancer cases were observed among 1,372,424 men and 804,077 women, respectively. The prediction models included age, BMI, family history, meal regularity, salt preference, alcohol consumption, smoking and physical activity for men, and age, BMI, family history, salt preference, alcohol consumption, and smoking for women. This prediction model showed good accuracy and predictability in both the developing and validation cohorts (C-statistics: 0.764 for men, 0.706 for women.In this study, a prediction model for gastric cancer incidence was developed that displayed a good performance.

  1. Predictive risk modelling under different data access scenarios: who is identified as high risk and for how long?

    Science.gov (United States)

    Johnson, Tracy L; Kaldor, Jill; Sutherland, Kim; Humphries, Jacob; Jorm, Louisa R; Levesque, Jean-Frederic

    2018-01-01

    Objective This observational study critically explored the performance of different predictive risk models simulating three data access scenarios, comparing: (1) sociodemographic and clinical profiles; (2) consistency in high-risk designation across models; and (3) persistence of high-risk status over time. Methods Cross-sectional health survey data (2006–2009) for more than 260 000 Australian adults 45+ years were linked to longitudinal individual hospital, primary care, pharmacy and mortality data. Three risk models predicting acute emergency hospitalisations were explored, simulating conditions where data are accessed through primary care practice management systems, or through hospital-based electronic records, or through a hypothetical ‘full’ model using a wider array of linked data. High-risk patients were identified using different risk score thresholds. Models were reapplied monthly for 24 months to assess persistence in high-risk categorisation. Results The three models displayed similar statistical performance. Three-quarters of patients in the high-risk quintile from the ‘full’ model were also identified using the primary care or hospital-based models, with the remaining patients differing according to age, frailty, multimorbidity, self-rated health, polypharmacy, prior hospitalisations and imminent mortality. The use of higher risk prediction thresholds resulted in lower levels of agreement in high-risk designation across models and greater morbidity and mortality in identified patient populations. Persistence of high-risk status varied across approaches according to updated information on utilisation history, with up to 25% of patients reassessed as lower risk within 1 year. Conclusion/implications Small differences in risk predictors or risk thresholds resulted in comparatively large differences in who was classified as high risk and for how long. Pragmatic predictive risk modelling design decisions based on data availability or projected

  2. Model of two infectious diseases in nettle caterpillar population

    Science.gov (United States)

    Firdausi, F. Z.; Nuraini, N.

    2016-04-01

    Palm oil is a vital commodity to the economy of Indonesia. The area of oil palm plantations in Indonesia has increased from year to year. However, the effectiveness of palm oil production is reduced by pest infestation. One of the pest which often infests oil palm plantations is nettle caterpillar. The pest control used in this study is biological control, viz. biological agents given to oil palm trees. This paper describes a mathematical model of two infectious diseases in nettle caterpillar population. The two infectious diseases arise due to two biological agents, namely Bacillus thuringiensis bacterium and parasite which usually attack nettle caterpillars. The derivation of the model constructed in this paper is obtained from ordinary differential equations without time delay. The equilibrium points are analyzed. Two of three equilibrium points are stable if the Routh-Hurwitz criteria are fulfilled. In addition, this paper also presents the numerical simulation of the model which has been constructed.

  3. Barriers of access to care in a managed competition model: lessons from Colombia

    Directory of Open Access Journals (Sweden)

    Mogollón-Pérez Amparo Susana

    2010-10-01

    Full Text Available Abstract Background The health sector reform in Colombia, initiated by Law 100 (1993 that introduced a managed competition model, is generally presented as a successful experience of improving access to care through a health insurance regulated market. The study's objective is to improve our understanding of the factors influencing access to the continuum of care in the Colombian managed competition model, from the social actors' point of view. Methods An exploratory, descriptive-interpretative qualitative study was carried out, based on case studies of four healthcare networks in rural and urban areas. Individual semi-structured interviews were conducted to a three stage theoretical sample: I cases, II providers and III informants: insured and uninsured users (35, health professionals (51, administrative personnel (20, and providers' (18 and insurers' (10 managers. Narrative content analysis was conducted; segmented by cases, informant's groups and themes. Results Access, particularly to secondary care, is perceived as complex due to four groups of obstacles with synergetic effects: segmented insurance design with insufficient services covered; insurers' managed care and purchasing mechanisms; providers' networks structural and organizational limitations; and, poor living conditions. Insurers' and providers' values based on economic profit permeate all factors. Variations became apparent between the two geographical areas and insurance schemes. In the urban areas barriers related to market functioning predominate, whereas in the rural areas structural deficiencies in health services are linked to insufficient public funding. While financial obstacles are dominant in the subsidized regime, in the contributory scheme supply shortage prevails, related to insufficient private investment. Conclusions The results show how in the Colombian healthcare system structural and organizational barriers to care access, that are common in developing countries

  4. Investigating Access Performance of Long Time Series with Restructured Big Model Data

    Science.gov (United States)

    Shen, S.; Ostrenga, D.; Vollmer, B.; Meyer, D. J.

    2017-12-01

    Data sets generated by models are substantially increasing in volume, due to increases in spatial and temporal resolution, and the number of output variables. Many users wish to download subsetted data in preferred data formats and structures, as it is getting increasingly difficult to handle the original full-size data files. For example, application research users, such as those involved with wind or solar energy, or extreme weather events, are likely only interested in daily or hourly model data at a single point or for a small area for a long time period, and prefer to have the data downloaded in a single file. With native model file structures, such as hourly data from NASA Modern-Era Retrospective analysis for Research and Applications Version-2 (MERRA-2), it may take over 10 hours for the extraction of interested parameters at a single point for 30 years. The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) is exploring methods to address this particular user need. One approach is to create value-added data by reconstructing the data files. Taking MERRA-2 data as an example, we have tested converting hourly data from one-day-per-file into different data cubes, such as one-month, one-year, or whole-mission. Performance are compared for reading local data files and accessing data through interoperable service, such as OPeNDAP. Results show that, compared to the original file structure, the new data cubes offer much better performance for accessing long time series. We have noticed that performance is associated with the cube size and structure, the compression method, and how the data are accessed. An optimized data cube structure will not only improve data access, but also may enable better online analytic services.

  5. The Atmospheric Chemistry and Canopy Exchange Simulation System (ACCESS: model description and application to a temperate deciduous forest canopy

    Directory of Open Access Journals (Sweden)

    R. D. Saylor

    2013-01-01

    Full Text Available Forest canopies are primary emission sources of biogenic volatile organic compounds (BVOCs and have the potential to significantly influence the formation and distribution of secondary organic aerosol (SOA mass. Biogenically-derived SOA formed as a result of emissions from the widespread forests across the globe may affect air quality in populated areas, degrade atmospheric visibility, and affect climate through direct and indirect forcings. In an effort to better understand the formation of SOA mass from forest emissions, a 1-D column model of the multiphase physical and chemical processes occurring within and just above a vegetative canopy is being developed. An initial, gas-phase-only version of this model, the Atmospheric Chemistry and Canopy Exchange Simulation System (ACCESS, includes processes accounting for the emission of BVOCs from the canopy, turbulent vertical transport within and above the canopy and throughout the height of the planetary boundary layer (PBL, near-explicit representation of chemical transformations, mixing with the background atmosphere and bi-directional exchange between the atmosphere and canopy and the atmosphere and forest floor. The model formulation of ACCESS is described in detail and results are presented for an initial application of the modeling system to Walker Branch Watershed, an isoprene-emission-dominated forest canopy in the southeastern United States which has been the focal point for previous chemical and micrometeorological studies. Model results of isoprene profiles and fluxes are found to be consistent with previous measurements made at the simulated site and with other measurements made in and above mixed deciduous forests in the southeastern United States. Sensitivity experiments are presented which explore how canopy concentrations and fluxes of gas-phase precursors of SOA are affected by background anthropogenic nitrogen oxides (NOx. Results from these experiments suggest that the

  6. Population Pharmacokinetic Modeling of a Desmopressin Oral Lyophilisate in Growing Piglets as a Model for the Pediatric Population

    Directory of Open Access Journals (Sweden)

    Elke Gasthuys

    2018-01-01

    Full Text Available Desmopressin is used to treat primary nocturnal enuresis in children. Over the years, various formulations of desmopressin were commercialized of which the sublingual melt tablet is preferred in the pediatric population, despite the lack of full PK studies in this population. A full PK study was performed in growing conventional piglets to evaluate if this juvenile animal model can provide supplementary information to complement the information gap in the pediatric population. A desmopressin sublingual melt tablet (120 μg was administered to 32 male piglets aged 8 days, 4 weeks, 7 weeks, and 6 months (each group n = 8. Population PK (pop-PK analysis was performed to derive the PK parameters, the between- and within-subject variabilities and the effects of covariates. Desmopressin demonstrated two-compartmental PK, with a dual, sequential absorption process, and linear elimination. Body weight was the only significant covariate on clearance and on apparent volume of distribution of the central compartment. In human pediatric trials, no double peak in the absorption phase was observed in the plasma concentration-time curves, possibly due to the sparse sampling strategy applied in those pediatric studies. Therefore, it is recommended to perform additional studies, based on the sampling protocol applied in the current study.

  7. Modelling the radioecological transfer of radiocaesium to three Swedish populations

    International Nuclear Information System (INIS)

    Raeaef, C.L.

    2005-01-01

    UNSCEAR has presented a terrestrial transfer model for predicting the annual average concentrations of radionuclides in important diet components and in humans based on the annual ground deposition from atmospheric fallout. The model is composed of three components, the principal component representing the direct contamination of fodder and crops, and the two remaining ones reflecting delayed transfer from previous fallout accumulated in soils. The model is intended to be used for protracted deposition of radionuclides and has been applied to observed time-patterns of 137 Cs body burdens in three different Swedish populations subjected to transfer from continuous nuclear weapons fallout during the 1960s and 1970s. The results show that the best agreement with observed body burden data is obtained by applying an effective ecological half-time, T eco,eff , for nuclear weapons fallout 137 Cs of 0.8 years for urban individuals in the South of Sweden, 2 years for urbans living in the Stockholm area and 4 years for reindeer herders in the middle of Sweden. When compared with the ecological half-times observed in the urban population after the Chernobyl fallout these values appear to be shorter

  8. Modelling biological invasions: Individual to population scales at interfaces

    KAUST Repository

    Belmonte-Beitia, J.

    2013-10-01

    Extracting the population level behaviour of biological systems from that of the individual is critical in understanding dynamics across multiple scales and thus has been the subject of numerous investigations. Here, the influence of spatial heterogeneity in such contexts is explored for interfaces with a separation of the length scales characterising the individual and the interface, a situation that can arise in applications involving cellular modelling. As an illustrative example, we consider cell movement between white and grey matter in the brain which may be relevant in considering the invasive dynamics of glioma. We show that while one can safely neglect intrinsic noise, at least when considering glioma cell invasion, profound differences in population behaviours emerge in the presence of interfaces with only subtle alterations in the dynamics at the individual level. Transport driven by local cell sensing generates predictions of cell accumulations along interfaces where cell motility changes. This behaviour is not predicted with the commonly used Fickian diffusion transport model, but can be extracted from preliminary observations of specific cell lines in recent, novel, cryo-imaging. Consequently, these findings suggest a need to consider the impact of individual behaviour, spatial heterogeneity and especially interfaces in experimental and modelling frameworks of cellular dynamics, for instance in the characterisation of glioma cell motility. © 2013 Elsevier Ltd.

  9. Border Collision Bifurcations in a Generalized Model of Population Dynamics

    Directory of Open Access Journals (Sweden)

    Lilia M. Ladino

    2016-01-01

    Full Text Available We analyze the dynamics of a generalized discrete time population model of a two-stage species with recruitment and capture. This generalization, which is inspired by other approaches and real data that one can find in literature, consists in considering no restriction for the value of the two key parameters appearing in the model, that is, the natural death rate and the mortality rate due to fishing activity. In the more general case the feasibility of the system has been preserved by posing opportune formulas for the piecewise map defining the model. The resulting two-dimensional nonlinear map is not smooth, though continuous, as its definition changes as any border is crossed in the phase plane. Hence, techniques from the mathematical theory of piecewise smooth dynamical systems must be applied to show that, due to the existence of borders, abrupt changes in the dynamic behavior of population sizes and multistability emerge. The main novelty of the present contribution with respect to the previous ones is that, while using real data, richer dynamics are produced, such as fluctuations and multistability. Such new evidences are of great interest in biology since new strategies to preserve the survival of the species can be suggested.

  10. Modelling biological invasions: Individual to population scales at interfaces

    KAUST Repository

    Belmonte-Beitia, J.; Woolley, T.E.; Scott, J.G.; Maini, P.K.; Gaffney, E.A.

    2013-01-01

    Extracting the population level behaviour of biological systems from that of the individual is critical in understanding dynamics across multiple scales and thus has been the subject of numerous investigations. Here, the influence of spatial heterogeneity in such contexts is explored for interfaces with a separation of the length scales characterising the individual and the interface, a situation that can arise in applications involving cellular modelling. As an illustrative example, we consider cell movement between white and grey matter in the brain which may be relevant in considering the invasive dynamics of glioma. We show that while one can safely neglect intrinsic noise, at least when considering glioma cell invasion, profound differences in population behaviours emerge in the presence of interfaces with only subtle alterations in the dynamics at the individual level. Transport driven by local cell sensing generates predictions of cell accumulations along interfaces where cell motility changes. This behaviour is not predicted with the commonly used Fickian diffusion transport model, but can be extracted from preliminary observations of specific cell lines in recent, novel, cryo-imaging. Consequently, these findings suggest a need to consider the impact of individual behaviour, spatial heterogeneity and especially interfaces in experimental and modelling frameworks of cellular dynamics, for instance in the characterisation of glioma cell motility. © 2013 Elsevier Ltd.

  11. Future Arctic marine access: analysis and evaluation of observations, models, and projections of sea ice

    Directory of Open Access Journals (Sweden)

    T. S. Rogers

    2013-02-01

    Full Text Available There is an emerging need for regional applications of sea ice projections to provide more accuracy and greater detail to scientists, national, state and local planners, and other stakeholders. The present study offers a prototype for a comprehensive, interdisciplinary study to bridge observational data, climate model simulations, and user needs. The study's first component is an observationally based evaluation of Arctic sea ice trends during 1980–2008, with an emphasis on seasonal and regional differences relative to the overall pan-Arctic trend. Regional sea ice loss has varied, with a significantly larger decline of winter maximum (January–March extent in the Atlantic region than in other sectors. A lead–lag regression analysis of Atlantic sea ice extent and ocean temperatures indicates that reduced sea ice extent is associated with increased Atlantic Ocean temperatures. Correlations between the two variables are greater when ocean temperatures lag rather than lead sea ice. The performance of 13 global climate models is evaluated using three metrics to compare sea ice simulations with the observed record. We rank models over the pan-Arctic domain and regional quadrants and synthesize model performance across several different studies. The best performing models project reduced ice cover across key access routes in the Arctic through 2100, with a lengthening of seasons for marine operations by 1–3 months. This assessment suggests that the Northwest and Northeast Passages hold potential for enhanced marine access to the Arctic in the future, including shipping and resource development opportunities.

  12. A model for increasing appreciation, accessibility and application of research in nursing.

    Science.gov (United States)

    Edward, Karen-Leigh

    2015-01-01

    The confidence and engagement of nurses (and midwives) in research are an area for continued development. The Research Appreciation, Accessibility, and Application Model (RAAAM), developed in 2011, provides a framework for enhancing research activities by nurses within the clinical setting. Unlike other models, the RAAAM does not assume a preexisting capacity or knowledge of research; however, the model incorporates the multiple research activities that comprise a research culture. Although it is acknowledged that undertaking a research project is not for everyone, using evidence-based knowledge for practice development is essential and relates to all clinical staff. The RAAAM model presents four domains-research appreciation, research accessibility, research application, and research sustainability. Research appreciation is a first step in realizing the potential beneficial impact of research in practice. Relating these activities to identified key result areas that are drawn from key stakeholders completes the loop, ensuring sustainability of research activities and processes. The model presented here offers a practical and user-friendly approach for research enhancement in nursing using the platform of a clinical and academic partnership. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Open Access Publishing in High-Energy Physics the SCOAP$^{3}$ model

    CERN Document Server

    Mele, S

    2009-01-01

    The Open Access (OA) movement is gaining an increasing momentum: its goal is to grant anyone, anywhere and anytime free access to the results of publicly funded scientific research. The High- Energy Physics (HEP) community has pioneered OA for decades, through its widespread “pre-print culture”. After almost half a century of worldwide dissemination of pre-prints, in paper first and electronically later, OA journals are becoming the natural evolution of scholarly communication in HEP. Among other OA business models, the one based on a sponsoring consortium appears as the most viable option for a transition of the HEP peer-reviewed literature to OA. The Sponsoring Consortium for Open Access Publishing in Particle Physics (SCOAP3) is proposed as a central body to remunerate publishers for their peer-review service, effectively replacing the “reader-pays” model of traditional subscriptions with an “author-side” funding, without any direct financial burden on individual authors and research groups. Su...

  14. The naming of gender-marked pronouns supports interactivity in models of lexical access

    Directory of Open Access Journals (Sweden)

    Albert Costa

    2009-01-01

    Full Text Available When a speaker names an object using a gender-marked pronominal form, the referent word corresponding to the target object has to be selected in order to access the grammatical gender. By contrast, the phonological content of the referent word is not needed. In two picture-naming interference experiments we explored whether the lexical selection of a referent word is affected by its phonological properties. In Experiment 1, Spanish participants named pictures using a sentence with a noun or a pronoun while ignoring words semantically or phonologically related. The results showed a semantic interference effect and a Phonological Facilitation Effect (PFE in both type of utterances. In Experiment 2 the PFE was replicated with Italian participants in a different pronominal utterance. The PFE suggests that the lexical selection of the referent word is facilitated by the presentation of a distractor word phonologically related. These findings are consistent with the predictions of interactive models of lexical access.

  15. A universal access layer for the Integrated Tokamak Modelling Task Force

    International Nuclear Information System (INIS)

    Manduchi, G.; Iannone, F.; Imbeaux, F.; Huysmans, G.; Lister, J.B.; Guillerminet, B.; Strand, P.; Eriksson, L.-G.; Romanelli, M.

    2008-01-01

    The Integrated Tokamak Modelling (ITM) Task Force aims at providing a suite of codes for preparing and analyzing future ITER discharges. In the framework of the ITM, the universal access layer (UAL) provides the capability of storing and retrieving data involved in simulation. The underlying data structure is hierarchical and the granularity in data access is given by the definition of a set of consistent physical objects (CPOs). To describe the data structure of the overall ITM database, the XML schema description (XSD) has been used. Originally intended to describe the structure of XML documents, XSD is used here to provide an unambiguous way of describing how data are structured, regardless of the actual implementation of the underlying database. The MDSplus-based UAL implementation is currently under test and other prototypes for investigating alternative data storage systems are foreseen

  16. Evolution of models of disability as a basis for further policy changes in accessible tourism

    Directory of Open Access Journals (Sweden)

    Alina Zajadacz

    2015-10-01

    Full Text Available Purpose – The purpose of this paper is to present the results of a critical analysis of the disability models developed to date and of how they function in practice. Furthermore, it aims to answer the following question: which model of disability (MD will provide the most suitable foundation for any course of action undertaken in the process of planning accessible tourism development in the future? Design/methodology/approach – In the first stage of the study a critical analysis of the MDs described in the literature as well as in selected reports and expert opinions relating to people with disability (PwD was performer. These findings then became the basis for the second stage of the study which focuses on identifying attitudes within society towards the types of tourism on offer connected to the analysed MDs. The applied research methods include an analysis of a survey (2013, 2014 carried out face-to-face and on the SurveyMonkey web site. The study group consisted of 619 people (from Poland, Russia, Germany, Portugal, Slovakia, Canada, Tunisia and Great Britain. Findings – The great diversity of disabilities makes finding a universal solution in the creation of accessible tourism supply a complex task. This supports the need for a flexible "mix of various models" aimed at finding optimal solutions and the personalisation of tourism. In this context the greatest potential in the development of accessible tourism are models which are a synthesis of many determiners of disability such as the biopsychosocial or the geographical model of disability. The dynamics of accessible tourism development is likely to be increasingly influenced by the economic model, reflecting current trends for the personalisation of tourism supply. Research limitations/implications – The survey was carried out mainly within the European Community, the exception being respondents from Irkutsk in eastern (Asian Russia. In order to gain a global view of the

  17. Toward a Multifaceted Model of Internet Access for Understanding Digital Divides: An Empirical Investigation

    NARCIS (Netherlands)

    van Deursen, Alexander Johannes Aloysius Maria; van Dijk, Johannes A.G.M.

    2015-01-01

    In this investigation, a multifaceted model of Internet appropriation that encompasses four types of access—motivational, material, skills, and usage—is tested with a representative sample of the Dutch population. The analysis indicates that while the digital divide policies' focus has moved to

  18. A fuzzy mathematical model of West Java population with logistic growth model

    Science.gov (United States)

    Nurkholipah, N. S.; Amarti, Z.; Anggriani, N.; Supriatna, A. K.

    2018-03-01

    In this paper we develop a mathematics model of population growth in the West Java Province Indonesia. The model takes the form as a logistic differential equation. We parameterize the model using several triples of data, and choose the best triple which has the smallest Mean Absolute Percentage Error (MAPE). The resulting model is able to predict the historical data with a high accuracy and it also able to predict the future of population number. Predicting the future population is among the important factors that affect the consideration is preparing a good management for the population. Several experiment are done to look at the effect of impreciseness in the data. This is done by considering a fuzzy initial value to the crisp model assuming that the model propagates the fuzziness of the independent variable to the dependent variable. We assume here a triangle fuzzy number representing the impreciseness in the data. We found that the fuzziness may disappear in the long-term. Other scenarios also investigated, such as the effect of fuzzy parameters to the crisp initial value of the population. The solution of the model is obtained numerically using the fourth-order Runge-Kutta scheme.

  19. Mathematical model of temephos resistance in Aedes aegypti mosquito population

    Science.gov (United States)

    Aldila, D.; Nuraini, N.; Soewono, E.; Supriatna, A. K.

    2014-03-01

    Aedes aegypti is the main vector of dengue disease in many tropical and sub-tropical countries. Dengue became major public concern in these countries due to the unavailability of vaccine or drugs for dengue disease in the market. Hence, the only way to control the spread of DF and DHF is by controlling the vectors carrying the disease, for instance with fumigation, temephos or genetic manipulation. Many previous studies conclude that Aedes aegypti may develop resistance to many kind of insecticide, including temephos. Mathematical model for transmission of temephos resistance in Aedes aegypti population is discussed in this paper. Nontrivial equilibrium point of the system and the corresponding existence are shown analytically. The model analysis have shown epidemiological trends condition that permits the coexistence of nontrivial equilibrium is given analytically. Numerical results are given to show parameter sensitivity and some cases of worsening effect values for illustrating possible conditions in the field.

  20. Stochastic Model for Population Exposed to Low Level Risk

    International Nuclear Information System (INIS)

    Merkle, J.M.

    1996-01-01

    In this paper the stochastic model for population size, i.e. calculation of the number of deaths due to lethal stochastic health effects caused by the exposure to low level ionising radiation is presented. The model is defined for subpopulation with parameter (a, b) being fixed. Using the corresponding density function, it is possible to find all the quantities of interest by averaging over whole possible values for (a, l). All processes ar at first defined for one radionuclide, exposure pathway and the health effect under consideration. The results obtained in this paper are the basic quantities in the risk assessment, loss of life expectancy etc. The results presented in this paper are also applicable to the other sources of low level risk, not only the radiation risk

  1. The Virtual Watershed Observatory: Cyberinfrastructure for Model-Data Integration and Access

    Science.gov (United States)

    Duffy, C.; Leonard, L. N.; Giles, L.; Bhatt, G.; Yu, X.

    2011-12-01

    The Virtual Watershed Observatory (VWO) is a concept where scientists, water managers, educators and the general public can create a virtual observatory from integrated hydrologic model results, national databases and historical or real-time observations via web services. In this paper, we propose a prototype for automated and virtualized web services software using national data products for climate reanalysis, soils, geology, terrain and land cover. The VWO has the broad purpose of making accessible water resource simulations, real-time data assimilation, calibration and archival at the scale of HUC 12 watersheds (Hydrologic Unit Code) anywhere in the continental US. Our prototype for model-data integration focuses on creating tools for fast data storage from selected national databases, as well as the computational resources necessary for a dynamic, distributed watershed simulation. The paper will describe cyberinfrastructure tools and workflow that attempts to resolve the problem of model-data accessibility and scalability such that individuals, research teams, managers and educators can create a WVO in a desired context. Examples are given for the NSF-funded Shale Hills Critical Zone Observatory and the European Critical Zone Observatories within the SoilTrEC project. In the future implementation of WVO services will benefit from the development of a cloud cyber infrastructure as the prototype evolves to data and model intensive computation for continental scale water resource predictions.

  2. Increasing Energy Access in Sub-Saharan Africa: Exploring Public-Private Models for Intervention

    Energy Technology Data Exchange (ETDEWEB)

    Bazilian, Morgan; Pless, Jacquelyn

    2014-01-16

    This report, by Morgan Bazilian and Jacquelyn Pless, examines ways that Energy+ could make a large impact in providing energy access to the poor, focusing on four promising models. While there remains a focus on a technology (PV), and a region (SSA) in this report, the models the authors explore are amenable to other specifications as well. Thus, the models presented provide an opportunity for stakeholders and the international community to collaborate and leverage capacities, resources, and networks. Of course, these models are only a few of the very wide range of possible mechanisms. They also are somewhat focused on engaging the private sector. The report does not provide a full context for the complex landscape of energy access and energy poverty. Rather, the paper is focused around the specifics of the interventions. It remains the case that the fundamental building blocks of capacity building, good governance and planning, and the ability to find funding for 'upfront' due diligence and analysis remain critical. Those items are, however, largely outside the scope of this short report.

  3. State-space modeling to support management of brucellosis in the Yellowstone bison population

    Science.gov (United States)

    Hobbs, N. Thompson; Geremia, Chris; Treanor, John; Wallen, Rick; White, P.J.; Hooten, Mevin B.; Rhyan, Jack C.

    2015-01-01

    The bison (Bison bison) of the Yellowstone ecosystem, USA, exemplify the difficulty of conserving large mammals that migrate across the boundaries of conservation areas. Bison are infected with brucellosis (Brucella abortus) and their seasonal movements can expose livestock to infection. Yellowstone National Park has embarked on a program of adaptive management of bison, which requires a model that assimilates data to support management decisions. We constructed a Bayesian state-space model to reveal the influence of brucellosis on the Yellowstone bison population. A frequency-dependent model of brucellosis transmission was superior to a density-dependent model in predicting out-of-sample observations of horizontal transmission probability. A mixture model including both transmission mechanisms converged on frequency dependence. Conditional on the frequency-dependent model, brucellosis median transmission rate was 1.87 yr−1. The median of the posterior distribution of the basic reproductive ratio (R0) was 1.75. Seroprevalence of adult females varied around 60% over two decades, but only 9.6 of 100 adult females were infectious. Brucellosis depressed recruitment; estimated population growth rate λ averaged 1.07 for an infected population and 1.11 for a healthy population. We used five-year forecasting to evaluate the ability of different actions to meet management goals relative to no action. Annually removing 200 seropositive female bison increased by 30-fold the probability of reducing seroprevalence below 40% and increased by a factor of 120 the probability of achieving a 50% reduction in transmission probability relative to no action. Annually vaccinating 200 seronegative animals increased the likelihood of a 50% reduction in transmission probability by fivefold over no action. However, including uncertainty in the ability to implement management by representing stochastic variation in the number of accessible bison dramatically reduced the probability of

  4. The pervasive crisis of diminishing radiation therapy access for vulnerable populations in the United States, part 1: African-American patients.

    Science.gov (United States)

    McClelland, Shearwood; Page, Brandi R; Jaboin, Jerry J; Chapman, Christina H; Deville, Curtiland; Thomas, Charles R

    2017-01-01

    African Americans experience the highest burden of cancer incidence and mortality in the United States and have been persistently less likely to receive interventional care, even when such care has been proven superior to conservative management by randomized controlled trials. The presence of disparities in access to radiation therapy (RT) for African American cancer patients has rarely been examined in an expansive fashion. An extensive literature search was performed using the PubMed database to examine studies investigating disparities in RT access for African Americans. A total of 55 studies were found, spanning 11 organ systems. Disparities in access to RT for African Americans were most prominently study in cancers of the breast (23 studies), prostate (7 studies), gynecologic system (5 studies), and hematologic system (5 studies). Disparities in RT access for African Americans were prevalent regardless of organ system studied and often occurred independently of socioeconomic status. Fifty of 55 studies (91%) involved analysis of a population-based database such as Surveillance, Epidemiology and End Result (SEER; 26 studies), SEER-Medicare (5 studies), National Cancer Database (3 studies), or a state tumor registry (13 studies). African Americans in the United States have diminished access to RT compared with Caucasian patients, independent of but often in concert with low socioeconomic status. These findings underscore the importance of finding systemic and systematic solutions to address these inequalities to reduce the barriers that patient race provides in receipt of optimal cancer care.

  5. Disparities in mobile phone access and maternal health service utilization in Nigeria: a population-based survey.

    Science.gov (United States)

    Jennings, Larissa; Omoni, Adetayo; Akerele, Akunle; Ibrahim, Yisa; Ekanem, Ekpenyong

    2015-05-01

    Mobile communication technologies may reduce maternal health disparities related to cost, distance, and infrastructure. However, the ability of mHealth initiatives to accelerate maternal health goals requires in part that women with the greatest health needs have access to mobile phones. This study examined if women with limited mobile phone access have differential odds of maternal knowledge and health service utilization as compared to female mobile phone users who are currently eligible to participate in maternal mHealth programs. Using household survey data from Nigeria, multivariable logistic regressions were used to examine the odds of maternal knowledge and service utilization by mobile phone strata. Findings showed that in settings with unequal access to mobile phones, mHealth interventions may not reach women who have the poorest maternal knowledge and care-seeking as these women often lacked mobile connectivity. As compared to mobile users, women without mobile phone access had significantly lower odds of antenatal care utilization (OR=0.48, 95%CI: 0.36-0.64), skilled delivery (OR=0.56, 95%CI: 0.45-0.70), and modern contraceptive use (OR=0.50, 95%CI: 0.33-0.76) after adjusting for demographic characteristics. They also had significantly lower knowledge of maternal danger signs (OR=0.69, 95%CI: 0.53-0.90) and knowledge of antenatal (OR=0.46, 95%CI: 0.36-0.59) and skilled delivery care benefits (OR=0.62, 95%CI: 0.47-0.82). No differences were observed by mobile phone strata in uptake of emergency obstetric care, postnatal services, or breastfeeding. As maternal mHealth strategies are increasingly utilized, more efforts are needed to improve women's access to mobile phones and minimize potential health inequities brought on by health systems and technological barriers in access to care. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  6. Yunnan-III models for evolutionary population synthesis

    Science.gov (United States)

    Zhang, F.; Li, L.; Han, Z.; Zhuang, Y.; Kang, X.

    2013-02-01

    We build the Yunnan-III evolutionary population synthesis (EPS) models by using the mesa stellar evolution code, BaSeL stellar spectra library and the initial mass functions (IMFs) of Kroupa and Salpeter, and present colours and integrated spectral energy distributions (ISEDs) of solar-metallicity stellar populations (SPs) in the range of 1 Myr to 15 Gyr. The main characteristic of the Yunnan-III EPS models is the usage of a set of self-consistent solar-metallicity stellar evolutionary tracks (the masses of stars are from 0.1 to 100 M⊙). This set of tracks is obtained by using the state-of-the-art mesa code. mesa code can evolve stellar models through thermally pulsing asymptotic giant branch (TP-AGB) phase for low- and intermediate-mass stars. By comparisons, we confirm that the inclusion of TP-AGB stars makes the V - K, V - J and V - R colours of SPs redder and the infrared flux larger at ages log(t/yr) ≳ 7.6 [the differences reach the maximum at log(t/yr) ˜ 8.6, ˜0.5-0.2 mag for colours, approximately two times for K-band flux]. We also find that the colour-evolution trends of Model with-TPAGB at intermediate and large ages are similar to those from the starburst99 code, which employs the Padova-AGB stellar library, BaSeL spectral library and the Kroupa IMF. At last, we compare the colours with the other EPS models comprising TP-AGB stars (such as CB07, M05, V10 and POPSTAR), and find that the B - V colour agrees with each other but the V-K colour shows a larger discrepancy among these EPS models [˜1 mag when 8 ≲ log(t/yr) ≲ 9]. The stellar evolutionary tracks, isochrones, colours and ISEDs can be obtained on request from the first author or from our website (http://www1.ynao.ac.cn/~zhangfh/). Using the isochrones, you can build your EPS models. Now the format of stellar evolutionary tracks is the same as that in the starburst99 code; you can put them into the starburst99 code and get the SP's results. Moreover, the colours involving other passbands

  7. Nuisance Source Population Modeling for Radiation Detection System Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sokkappa, P; Lange, D; Nelson, K; Wheeler, R

    2009-10-05

    A major challenge facing the prospective deployment of radiation detection systems for homeland security applications is the discrimination of radiological or nuclear 'threat sources' from radioactive, but benign, 'nuisance sources'. Common examples of such nuisance sources include naturally occurring radioactive material (NORM), medical patients who have received radioactive drugs for either diagnostics or treatment, and industrial sources. A sensitive detector that cannot distinguish between 'threat' and 'benign' classes will generate false positives which, if sufficiently frequent, will preclude it from being operationally deployed. In this report, we describe a first-principles physics-based modeling approach that is used to approximate the physical properties and corresponding gamma ray spectral signatures of real nuisance sources. Specific models are proposed for the three nuisance source classes - NORM, medical and industrial. The models can be validated against measured data - that is, energy spectra generated with the model can be compared to actual nuisance source data. We show by example how this is done for NORM and medical sources, using data sets obtained from spectroscopic detector deployments for cargo container screening and urban area traffic screening, respectively. In addition to capturing the range of radioactive signatures of individual nuisance sources, a nuisance source population model must generate sources with a frequency of occurrence consistent with that found in actual movement of goods and people. Measured radiation detection data can indicate these frequencies, but, at present, such data are available only for a very limited set of locations and time periods. In this report, we make more general estimates of frequencies for NORM and medical sources using a range of data sources such as shipping manifests and medical treatment statistics. We also identify potential data sources for industrial

  8. Editors View the Continuous Publication Model as a Satisfactory Alternative for Open Access LIS Journals

    Directory of Open Access Journals (Sweden)

    Richard Hayman

    2014-09-01

    Full Text Available A Review of: Cirasella, J., & Bowdoin, S. (2013. Just roll with it? Rolling volumes vs. discrete issues in open access library and information science journals. Journal of Librarianship and Scholarly Communication, 1(4. http://dx.doi.org/10.7710/2162-3309.1086 Abstract Objective – To understand the prevalence of, motivations for, and satisfaction with using a rolling-volume publishing model, as opposed to publishing discrete issues, across open access academic journals in library and information science. Design – A 12 question survey questionnaire. Setting – English-language, open access library and information science (LIS journals published in the United States of America. Subjects – A total of 21 open access LIS journals identified via the Directory of Open Access Journals that were actively publishing, and that also met the authors’ standard of scholarliness, which they established by identifying a journal’s peer-review process or other evidence of rigorous review. Based on responses, 12 journals published using discrete issues, while 9 published as rolling volumes or as rolling volumes with some discrete issues. Methods – In late 2011, the study’s authors invited lead editors or primary journal contacts to complete the survey. Survey participants were asked to identify whether their journal published in discrete issues, rolling volumes, or rolling volumes with occasional discrete issues, with the latter two categories combined as one for ease of results analysis. Survey logic split respondents into two groups, either discrete-issue or rolling-volume. Respondents in both categories were posed similar sets of questions, with the key difference being that the questions directed at each category accounted for the publication model the journals themselves identified as using. Editors from both groups were asked about the reasons for using the publication model they identified for their journal: within the survey tool, authors

  9. From the Margins to the Spotlight: Diverse Deaf and Hard of Hearing Student Populations and Standardized Assessment Accessibility

    Science.gov (United States)

    Cawthon, Stephanie

    2015-01-01

    Designing assessments and tests is one of the more challenging aspects of creating an accessible learning environment for students who are deaf or hard of hearing (DHH), particularly for deaf students with a disability (DWD). Standardized assessments are a key mechanism by which the educational system in the United States measures student…

  10. A new model with an anatomically accurate human renal collecting system for training in fluoroscopy-guided percutaneous nephrolithotomy access.

    Science.gov (United States)

    Turney, Benjamin W

    2014-03-01

    Obtaining renal access is one of the most important and complex steps in learning percutaneous nephrolithotomy (PCNL). Ideally, this skill should be practiced outside the operating room. There is a need for anatomically accurate and cheap models for simulated training. The objective was to develop a cost-effective, anatomically accurate, nonbiologic training model for simulated PCNL access under fluoroscopic guidance. Collecting systems from routine computed tomography urograms were extracted and reformatted using specialized software. These images were printed in a water-soluble plastic on a three-dimensional (3D) printer to create biomodels. These models were embedded in silicone and then the models were dissolved in water to leave a hollow collecting system within a silicone model. These PCNL models were filled with contrast medium and sealed. A layer of dense foam acted as a spacer to replicate the tissues between skin and kidney. 3D printed models of human collecting systems are a useful adjunct in planning PCNL access. The PCNL access training model is relatively low cost and reproduces the anatomy of the renal collecting system faithfully. A range of models reflecting the variety and complexity of human collecting systems can be reproduced. The fluoroscopic triangulation process needed to target the calix of choice can be practiced successfully in this model. This silicone PCNL training model accurately replicates the anatomic architecture and orientation of the human renal collecting system. It provides a safe, clean, and effective model for training in accurate fluoroscopy-guided PCNL access.

  11. The Influence of Normalization Weight in Population Pharmacokinetic Covariate Models.

    Science.gov (United States)

    Goulooze, Sebastiaan C; Völler, Swantje; Välitalo, Pyry A J; Calvier, Elisa A M; Aarons, Leon; Krekels, Elke H J; Knibbe, Catherijne A J

    2018-03-23

    In covariate (sub)models of population pharmacokinetic models, most covariates are normalized to the median value; however, for body weight, normalization to 70 kg or 1 kg is often applied. In this article, we illustrate the impact of normalization weight on the precision of population clearance (CL pop ) parameter estimates. The influence of normalization weight (70, 1 kg or median weight) on the precision of the CL pop estimate, expressed as relative standard error (RSE), was illustrated using data from a pharmacokinetic study in neonates with a median weight of 2.7 kg. In addition, a simulation study was performed to show the impact of normalization to 70 kg in pharmacokinetic studies with paediatric or obese patients. The RSE of the CL pop parameter estimate in the neonatal dataset was lowest with normalization to median weight (8.1%), compared with normalization to 1 kg (10.5%) or 70 kg (48.8%). Typical clearance (CL) predictions were independent of the normalization weight used. Simulations showed that the increase in RSE of the CL pop estimate with 70 kg normalization was highest in studies with a narrow weight range and a geometric mean weight away from 70 kg. When, instead of normalizing with median weight, a weight outside the observed range is used, the RSE of the CL pop estimate will be inflated, and should therefore not be used for model selection. Instead, established mathematical principles can be used to calculate the RSE of the typical CL (CL TV ) at a relevant weight to evaluate the precision of CL predictions.

  12. Providing comprehensive and consistent access to astronomical observatory archive data: the NASA archive model

    Science.gov (United States)

    McGlynn, Thomas; Fabbiano, Giuseppina; Accomazzi, Alberto; Smale, Alan; White, Richard L.; Donaldson, Thomas; Aloisi, Alessandra; Dower, Theresa; Mazzerella, Joseph M.; Ebert, Rick; Pevunova, Olga; Imel, David; Berriman, Graham B.; Teplitz, Harry I.; Groom, Steve L.; Desai, Vandana R.; Landry, Walter

    2016-07-01

    Since the turn of the millennium a constant concern of astronomical archives have begun providing data to the public through standardized protocols unifying data from disparate physical sources and wavebands across the electromagnetic spectrum into an astronomical virtual observatory (VO). In October 2014, NASA began support for the NASA Astronomical Virtual Observatories (NAVO) program to coordinate the efforts of NASA astronomy archives in providing data to users through implementation of protocols agreed within the International Virtual Observatory Alliance (IVOA). A major goal of the NAVO collaboration has been to step back from a piecemeal implementation of IVOA standards and define what the appropriate presence for the US and NASA astronomy archives in the VO should be. This includes evaluating what optional capabilities in the standards need to be supported, the specific versions of standards that should be used, and returning feedback to the IVOA, to support modifications as needed. We discuss a standard archive model developed by the NAVO for data archive presence in the virtual observatory built upon a consistent framework of standards defined by the IVOA. Our standard model provides for discovery of resources through the VO registries, access to observation and object data, downloads of image and spectral data and general access to archival datasets. It defines specific protocol versions, minimum capabilities, and all dependencies. The model will evolve as the capabilities of the virtual observatory and needs of the community change.

  13. Analysis and modeling of resistive switching mechanisms oriented to resistive random-access memory

    International Nuclear Information System (INIS)

    Huang Da; Wu Jun-Jie; Tang Yu-Hua

    2013-01-01

    With the progress of the semiconductor industry, the resistive random-access memory (RAM) has drawn increasing attention. The discovery of the memristor has brought much attention to this study. Research has focused on the resistive switching characteristics of different materials and the analysis of resistive switching mechanisms. We discuss the resistive switching mechanisms of different materials in this paper and analyze the differences of those mechanisms from the view point of circuitry to establish their respective circuit models. Finally, simulations are presented. We give the prospect of using different materials in resistive RAM on account of their resistive switching mechanisms, which are applied to explain their resistive switchings

  14. A demographic model to predict future growth of the Addo elephant population

    OpenAIRE

    A.M. Woodd

    1999-01-01

    An age-structured demographic model of the growth of the Addo elephant population was developed using parameters calculated from long-term data on the population. The model was used to provide estimates of future population growth. Expansion of the Addo Elephant National Park is currently underway, and the proposed target population size for elephant within the enlarged park is 2700. The model predicts that this population size will be reached during the year 2043, so that the Addo elephant p...

  15. Skeeter Buster: a stochastic, spatially explicit modeling tool for studying Aedes aegypti population replacement and population suppression strategies.

    Directory of Open Access Journals (Sweden)

    Krisztian Magori

    2009-09-01

    Full Text Available Dengue is the most important mosquito-borne viral disease affecting humans. The only prevention measure currently available is the control of its vectors, primarily Aedes aegypti. Recent advances in genetic engineering have opened the possibility for a new range of control strategies based on genetically modified mosquitoes. Assessing the potential efficacy of genetic (and conventional strategies requires the availability of modeling tools that accurately describe the dynamics and genetics of Ae. aegypti populations.We describe in this paper a new modeling tool of Ae. aegypti population dynamics and genetics named Skeeter Buster. This model operates at the scale of individual water-filled containers for immature stages and individual properties (houses for adults. The biology of cohorts of mosquitoes is modeled based on the algorithms used in the non-spatial Container Inhabiting Mosquitoes Simulation Model (CIMSiM. Additional features incorporated into Skeeter Buster include stochasticity, spatial structure and detailed population genetics. We observe that the stochastic modeling of individual containers in Skeeter Buster is associated with a strongly reduced temporal variation in stage-specific population densities. We show that heterogeneity in container composition of individual properties has a major impact on spatial heterogeneity in population density between properties. We detail how adult dispersal reduces this spatial heterogeneity. Finally, we present the predicted genetic structure of the population by calculating F(ST values and isolation by distance patterns, and examine the effects of adult dispersal and container movement between properties.We demonstrate that the incorporated stochasticity and level of spatial detail have major impacts on the simulated population dynamics, which could potentially impact predictions in terms of control measures. The capacity to describe population genetics confers the ability to model the outcome

  16. Explaining the Linguistic Diversity of Sahul Using Population Models

    Science.gov (United States)

    Reesink, Ger; Singer, Ruth; Dunn, Michael

    2009-01-01

    The region of the ancient Sahul continent (present day Australia and New Guinea, and surrounding islands) is home to extreme linguistic diversity. Even apart from the huge Austronesian language family, which spread into the area after the breakup of the Sahul continent in the Holocene, there are hundreds of languages from many apparently unrelated families. On each of the subcontinents, the generally accepted classification recognizes one large, widespread family and a number of unrelatable smaller families. If these language families are related to each other, it is at a depth which is inaccessible to standard linguistic methods. We have inferred the history of structural characteristics of these languages under an admixture model, using a Bayesian algorithm originally developed to discover populations on the basis of recombining genetic markers. This analysis identifies 10 ancestral language populations, some of which can be identified with clearly defined phylogenetic groups. The results also show traces of early dispersals, including hints at ancient connections between Australian languages and some Papuan groups (long hypothesized, never before demonstrated). Systematic language contact effects between members of big phylogenetic groups are also detected, which can in some cases be identified with a diffusional or substrate signal. Most interestingly, however, there remains striking evidence of a phylogenetic signal, with many languages showing negligible amounts of admixture. PMID:19918360

  17. Effect of modelling slum populations on influenza spread in Delhi

    Science.gov (United States)

    Chen, Jiangzhuo; Chu, Shuyu; Chungbaek, Youngyun; Khan, Maleq; Kuhlman, Christopher; Marathe, Achla; Mortveit, Henning; Vullikanti, Anil; Xie, Dawen

    2016-01-01

    Objectives This research studies the impact of influenza epidemic in the slum and non-slum areas of Delhi, the National Capital Territory of India, by taking proper account of slum demographics and residents’ activities, using a highly resolved social contact network of the 13.8 million residents of Delhi. Methods An SEIR model is used to simulate the spread of influenza on two different synthetic social contact networks of Delhi, one where slums and non-slums are treated the same in terms of their demographics and daily sets of activities and the other, where slum and non-slum regions have different attributes. Results Differences between the epidemic outcomes on the two networks are large. Time-to-peak infection is overestimated by several weeks, and the cumulative infection rate and peak infection rate are underestimated by 10–50%, when slum attributes are ignored. Conclusions Slum populations have a significant effect on influenza transmission in urban areas. Improper specification of slums in large urban regions results in underestimation of infections in the entire population and hence will lead to misguided interventions by policy planners. PMID:27687898

  18. Toward population management in an integrated care model.

    Science.gov (United States)

    Maddux, Franklin W; McMurray, Stephen; Nissenson, Allen R

    2013-01-01

    Under the Patient Protection and Affordable Care Act of 2010, accountable care organizations (ACOs) will be the primary mechanism for achieving the dual goals of high-quality patient care at managed per capita costs. To achieve these goals in the newly emerging health care environment, the nephrology community must plan for and direct integrated delivery and coordination of renal care, focusing on population management. Even though the ESRD patient population is a complex group with comorbid conditions that may confound integration of care, the nephrology community has unique experience providing integrated care through ACO-like programs. Specifically, the recent ESRD Management Demonstration Project sponsored by the Centers for Medicare & Medicaid Services and the current ESRD Prospective Payment System with it Quality Incentive Program have demonstrated that integrated delivery of renal care can be accomplished in a manner that provides improved clinical outcomes with some financial margin of savings. Moving forward, integrated renal care will probably be linked to provider performance and quality outcomes measures, and clinical integration initiatives will share several common elements, namely performance-based payment models, coordination of communication via health care information technology, and development of best practices for care coordination and resource utilization. Integration initiatives must be designed to be measured and evaluated, and, consistent with principles of continuous quality improvement, each initiative will provide for iterative improvements of the initiative. © 2013 S. Karger AG, Basel.

  19. Evolving provider payment models and patient access to innovative medical technology.

    Science.gov (United States)

    Long, Genia; Mortimer, Richard; Sanzenbacher, Geoffrey

    2014-12-01

    Abstract Objective: To investigate the evolving use and expected impact of pay-for-performance (P4P) and risk-based provider reimbursement on patient access to innovative medical technology. Structured interviews with leading private payers representing over 110 million commercially-insured lives exploring current and planned use of P4P provider payment models, evidence requirements for technology assessment and new technology coverage, and the evolving relationship between the two topics. Respondents reported rapid increases in the use of P4P and risk-sharing programs, with roughly half of commercial lives affected 3 years ago, just under two-thirds today, and an expected three-quarters in 3 years. All reported well-established systems for evaluating new technology coverage. Five of nine reported becoming more selective in the past 3 years in approving new technologies; four anticipated that in the next 3 years there will be a higher evidence requirement for new technology access. Similarly, four expected it will become more difficult for clinically appropriate but costly technologies to gain coverage. All reported planning to rely more on these types of provider payment incentives to control costs, but didn't see them as a substitute for payer technology reviews and coverage limitations; they each have a role to play. Interviews limited to nine leading payers with models in place; self-reported data. Likely implications include a more uncertain payment environment for providers, and indirectly for innovative medical technology and future investment, greater reliance on quality and financial metrics, and increased evidence requirements for favorable coverage and utilization decisions. Increasing provider financial risk may challenge the traditional technology adoption paradigm, where payers assumed a 'gatekeeping' role and providers a countervailing patient advocacy role with regard to access to new technology. Increased provider financial risk may result in an

  20. Train station access and train use: a joint stated and revealed preference choice modelling study

    NARCIS (Netherlands)

    La Paix Puello, Lissy Cesarina; Geurs, Karst Teunis; Geurs, K.T.; Patuelli, R.; Dentinho, T.

    2016-01-01

    Public transport accessibility depends not only on the places and opportunities that can be reached by transit, but also on accessibility to public transport. The characteristics of access and egress modes influence accessibility patterns but also ridership levels of public transport modes. In

  1. NODC Standard Format Herring Survey Population Density and Distribution (F057) Data (1976-1977) (NODC Accession 0014189)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data type contains data from aircraft surveys of herring schools. These data were collected to provide information on herring population density and...

  2. Perti Net-Based Workflow Access Control Model%基于Perti网的工作流访问控制模型研究

    Institute of Scientific and Technical Information of China (English)

    陈卓; 骆婷; 石磊; 洪帆

    2004-01-01

    Access control is an important protection mechanism for information systems.This paper shows how to make access control in workflow system.We give a workflow access control model (WACM) based on several current access control models.The model supports roles assignment and dynamic authorization.The paper defines the workflow using Petri net.It firstly gives the definition and description of the workflow, and then analyzes the architecture of the workflow access control model (WACM).Finally, an example of an e-commerce workflow access control model is discussed in detail.

  3. Utility of routine postoperative visit after appendectomy and cholecystectomy with evaluation of mobile technology access in an urban safety net population.

    Science.gov (United States)

    Chen, Diane W; Davis, Rachel W; Balentine, Courtney J; Scott, Aaron R; Gao, Yue; Tapia, Nicole M; Berger, David H; Suliburk, James W

    2014-08-01

    The value of routine postoperative visits after general surgery remains unclear. The objective of this study was to evaluate the utility of routine postoperative visits after appendectomy and cholecystectomy and to determine access to mobile technology as an alternative platform for follow-up. Retrospective review of 219 appendectomies and 200 cholecystectomies performed at a safety net hospital. One patient underwent both surgeries. Patient demographics, duration of clinic visit, and need for additional imaging, tests or readmissions were recorded. Access to mobile technology was surveyed by a validated questionnaire. Of 418 patients, 84% percent completed a postoperative visit. At follow-up, 58 patients (14%) required 70 interventions, including staple removal (16, 23%), suture removal (4, 6%), drain removal (8, 11%), additional follow-up (20, 28%), medication action (16, 21%), additional imaging (3, 4%), and readmission (1, 1%). Occupational paperwork (62) and nonsurgical clinic referrals (28) were also performed. Average check-in to check-out time was 100 ± 54 min per patient. One intervention was performed for every 7.8 h of time in the clinic. Additionally, 88% of the surveyed population reported access to cell phone technology, and 69% of patients mobile technology, which is pervasive in our population. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Web-accessible molecular modeling with Rosetta: The Rosetta Online Server that Includes Everyone (ROSIE).

    Science.gov (United States)

    Moretti, Rocco; Lyskov, Sergey; Das, Rhiju; Meiler, Jens; Gray, Jeffrey J

    2018-01-01

    The Rosetta molecular modeling software package provides a large number of experimentally validated tools for modeling and designing proteins, nucleic acids, and other biopolymers, with new protocols being added continually. While freely available to academic users, external usage is limited by the need for expertise in the Unix command line environment. To make Rosetta protocols available to a wider audience, we previously created a web server called Rosetta Online Server that Includes Everyone (ROSIE), which provides a common environment for hosting web-accessible Rosetta protocols. Here we describe a simplification of the ROSIE protocol specification format, one that permits easier implementation of Rosetta protocols. Whereas the previous format required creating multiple separate files in different locations, the new format allows specification of the protocol in a single file. This new, simplified protocol specification has more than doubled the number of Rosetta protocols available under ROSIE. These new applications include pK a determination, lipid accessibility calculation, ribonucleic acid redesign, protein-protein docking, protein-small molecule docking, symmetric docking, antibody docking, cyclic toxin docking, critical binding peptide determination, and mapping small molecule binding sites. ROSIE is freely available to academic users at http://rosie.rosettacommons.org. © 2017 The Protein Society.

  5. Decentralized Opportunistic Spectrum Resources Access Model and Algorithm toward Cooperative Ad-Hoc Networks

    Science.gov (United States)

    Liu, Ming; Xu, Yang; Mohammed, Abdul-Wahid

    2016-01-01

    Limited communication resources have gradually become a critical factor toward efficiency of decentralized large scale multi-agent coordination when both system scales up and tasks become more complex. In current researches, due to the agent’s limited communication and observational capability, an agent in a decentralized setting can only choose a part of channels to access, but cannot perceive or share global information. Each agent’s cooperative decision is based on the partial observation of the system state, and as such, uncertainty in the communication network is unavoidable. In this situation, it is a major challenge working out cooperative decision-making under uncertainty with only a partial observation of the environment. In this paper, we propose a decentralized approach that allows agents cooperatively search and independently choose channels. The key to our design is to build an up-to-date observation for each agent’s view so that a local decision model is achievable in a large scale team coordination. We simplify the Dec-POMDP model problem, and each agent can jointly work out its communication policy in order to improve its local decision utilities for the choice of communication resources. Finally, we discuss an implicate resource competition game, and show that, there exists an approximate resources access tradeoff balance between agents. Based on this discovery, the tradeoff between real-time decision-making and the efficiency of cooperation using these channels can be well improved. PMID:26727504

  6. Decentralized Opportunistic Spectrum Resources Access Model and Algorithm toward Cooperative Ad-Hoc Networks.

    Directory of Open Access Journals (Sweden)

    Ming Liu

    Full Text Available Limited communication resources have gradually become a critical factor toward efficiency of decentralized large scale multi-agent coordination when both system scales up and tasks become more complex. In current researches, due to the agent's limited communication and observational capability, an agent in a decentralized setting can only choose a part of channels to access, but cannot perceive or share global information. Each agent's cooperative decision is based on the partial observation of the system state, and as such, uncertainty in the communication network is unavoidable. In this situation, it is a major challenge working out cooperative decision-making under uncertainty with only a partial observation of the environment. In this paper, we propose a decentralized approach that allows agents cooperatively search and independently choose channels. The key to our design is to build an up-to-date observation for each agent's view so that a local decision model is achievable in a large scale team coordination. We simplify the Dec-POMDP model problem, and each agent can jointly work out its communication policy in order to improve its local decision utilities for the choice of communication resources. Finally, we discuss an implicate resource competition game, and show that, there exists an approximate resources access tradeoff balance between agents. Based on this discovery, the tradeoff between real-time decision-making and the efficiency of cooperation using these channels can be well improved.

  7. Model Based User's Access Requirement Analysis of E-Governance Systems

    Science.gov (United States)

    Saha, Shilpi; Jeon, Seung-Hwan; Robles, Rosslin John; Kim, Tai-Hoon; Bandyopadhyay, Samir Kumar

    The strategic and contemporary importance of e-governance has been recognized across the world. In India too, various ministries of Govt. of India and State Governments have taken e-governance initiatives to provide e-services to citizens and the business they serve. To achieve the mission objectives, and make such e-governance initiatives successful it would be necessary to improve the trust and confidence of the stakeholders. It is assumed that the delivery of government services will share the same public network information that is being used in the community at large. In particular, the Internet will be the principal means by which public access to government and government services will be achieved. To provide the security measures main aim is to identify user's access requirement for the stakeholders and then according to the models of Nath's approach. Based on this analysis, the Govt. can also make standards of security based on the e-governance models. Thus there will be less human errors and bias. This analysis leads to the security architecture of the specific G2C application.

  8. CERN Action on Open Access : Open Meeting on Changing the Publishing Model

    CERN Multimedia

    CERN. Geneva

    2005-01-01

    Leader of the discussion: Chief Scientific Officer Jos Engelen, CERN. Particle physicists are again contributing to change by Director-General Robert Aymar, CERN. A general presentation of the CERN policy and visions. Improving the impact of your research by Former Editor-in-Chief Alex Bradshaw, New Journal of Physics. Springer Open Choice by Chief executive officer Derk Haank, Springer. The JHEP experience by Scientific director Hector Rubinstein, JHEP. The impact of the J series, existing and coming journals: JHEP JCAP JSTAT JINST. National libraries ensuring long-term archiving of digital information speaker to be decided. Debate The Director-General is calling all CERN editors and authors to a meeting to contribute to the discussion on the direction that CERN should take in its experimentation with new publishing models. The current subscription-funded publishing model for journal articles (where access to a particular journal is granted upon payment of a subscription, often arranged by the institutional ...

  9. NOAA Operational Model Archive Distribution System (NOMADS): High Availability Applications for Reliable Real Time Access to Operational Model Data

    Science.gov (United States)

    Alpert, J. C.; Wang, J.

    2009-12-01

    To reduce the impact of natural hazards and environmental changes, the National Centers for Environmental Prediction (NCEP) provide first alert and a preferred partner for environmental prediction services, and represents a critical national resource to operational and research communities affected by climate, weather and water. NOMADS is now delivering high availability services as part of NOAA’s official real time data dissemination at its Web Operations Center (WOC) server. The WOC is a web service used by organizational units in and outside NOAA, and acts as a data repository where public information can be posted to a secure and scalable content server. A goal is to foster collaborations among the research and education communities, value added retailers, and public access for science and development efforts aimed at advancing modeling and GEO-related tasks. The user (client) executes what is efficient to execute on the client and the server efficiently provides format independent access services. Client applications can execute on the server, if it is desired, but the same program can be executed on the client side with no loss of efficiency. In this way this paradigm lends itself to aggregation servers that act as servers of servers listing, searching catalogs of holdings, data mining, and updating information from the metadata descriptions that enable collections of data in disparate places to be simultaneously accessed, with results processed on servers and clients to produce a needed answer. The services used to access the operational model data output are the Open-source Project for a Network Data Access Protocol (OPeNDAP), implemented with the Grid Analysis and Display System (GrADS) Data Server (GDS), and applications for slicing, dicing and area sub-setting the large matrix of real time model data holdings. This approach insures an efficient use of computer resources because users transmit/receive only the data necessary for their tasks including

  10. Modelling future oil production, population and the economy

    Energy Technology Data Exchange (ETDEWEB)

    Laherrere, Jean

    2003-07-01

    Most published data on energy, population and the economy are unreliable. In many cases, authors have political motives, selectively choosing data from a wide range of uncertainty to give a desired image. In addition to the uncertainty of the measurements themselves, as in the case of population or the confidentiality of the oil reserves, they often indulge in manipulation. A so-called hedonistic factor distorts the calculation of GDP in the United States; and the definition of the Proved Reserves by the Securities and Exchange Commission gives rise to 'reserve growth'. OPEC misreports its oil reserves because its quotas depend upon the reported reserves, and the reserves were overestimated in the Soviet Union because economic and technical constraints were ignored. Our present culture of eternal growth makes the word 'decline' politically incorrect, but constant growth is unsustainable in a finite world. Growth is the Santa Claus of the modern age who is supposed to provide welfare and retirement for our children and us. All natural events, when measured over their full life, can be modelled under one or more cycles, as in the Fourier analysis. This cyclical nature corresponds with the finite nature of the Universe; everything that is born will die, whether we speak of the solar system, the Earth, or human species. What goes up must come down. The Russian population is already declining and Europe's will soon do so too. This basic understanding was recognised by the celebrated King Hubbert when he made his famous prediction in 1956 that US oil production would peak in 1970. But, in fact, he oversimplified by showing a single peak. In reality, US oil production had a secondary peak (93% of the first one) in 1985, reflecting the entry of Alaskan production, which itself peaked in 1988. A symmetrical oil cycle reflects a large number of independent producers, acting randomly, but in many cases economic and political factors disturb the

  11. Modelling future oil production, population and the economy

    Energy Technology Data Exchange (ETDEWEB)

    Laherrere, Jean

    2003-07-01

    Most published data on energy, population and the economy are unreliable. In many cases, authors have political motives, selectively choosing data from a wide range of uncertainty to give a desired image. In addition to the uncertainty of the measurements themselves, as in the case of population or the confidentiality of the oil reserves, they often indulge in manipulation. A so-called hedonistic factor distorts the calculation of GDP in the United States; and the definition of the Proved Reserves by the Securities and Exchange Commission gives rise to 'reserve growth'. OPEC misreports its oil reserves because its quotas depend upon the reported reserves, and the reserves were overestimated in the Soviet Union because economic and technical constraints were ignored. Our present culture of eternal growth makes the word 'decline' politically incorrect, but constant growth is unsustainable in a finite world. Growth is the Santa Claus of the modern age who is supposed to provide welfare and retirement for our children and us. All natural events, when measured over their full life, can be modelled under one or more cycles, as in the Fourier analysis. This cyclical nature corresponds with the finite nature of the Universe; everything that is born will die, whether we speak of the solar system, the Earth, or human species. What goes up must come down. The Russian population is already declining and Europe's will soon do so too. This basic understanding was recognised by the celebrated King Hubbert when he made his famous prediction in 1956 that US oil production would peak in 1970. But, in fact, he oversimplified by showing a single peak. In reality, US oil production had a secondary peak (93% of the first one) in 1985, reflecting the entry of Alaskan production, which itself peaked in 1988. A symmetrical oil cycle reflects a large number of independent producers, acting randomly, but in many cases economic and political factors disturb the pattern, giving one or more new

  12. A model of alcohol drinking under an intermittent access schedule using group-housed mice.

    Directory of Open Access Journals (Sweden)

    Magdalena Smutek

    Full Text Available Here, we describe a new model of voluntary alcohol drinking by group-housed mice. The model employs sensor-equipped cages that track the behaviors of the individual animals via implanted radio chips. After the animals were allowed intermittent access to alcohol (three 24 h intervals every week for 4 weeks, the proportions of licks directed toward bottles containing alcohol were 50.9% and 39.6% for the male and female mice, respectively. We used three approaches (i.e., quinine adulteration, a progressive ratio schedule and a schedule involving a risk of punishment to test for symptoms of compulsive alcohol drinking. The addition of 0.01% quinine to the alcohol solution did not significantly affect intake, but 0.03% quinine induced a greater than 5-fold reduction in the number of licks on the alcohol bottles. When the animals were required to perform increasing numbers of instrumental responses to obtain access to the bottle with alcohol (i.e., a progressive ratio schedule, they frequently reached a maximum of 21 responses irrespective of the available reward. Although the mice rarely achieved higher response criteria, the number of attempts was ∼ 10 times greater in case of alcohol than water. We have developed an approach for mapping social interactions among animals that is based on analysis of the sequences of entries into the cage corners. This approach allowed us to identify the mice that followed other animals in non-random fashions. Approximately half of the mice displayed at least one interaction of this type. We have not yet found a clear correlation between imitative behavior and relative alcohol preference. In conclusion, the model we describe avoids the limitations associated with testing isolated animals and reliably leads to stable alcohol drinking. Therefore, this model may be well suited to screening for the effects of genetic mutations or pharmacological treatments on alcohol-induced behaviors.

  13. Discrete bivariate population balance modelling of heteroaggregation processes.

    Science.gov (United States)

    Rollié, Sascha; Briesen, Heiko; Sundmacher, Kai

    2009-08-15

    Heteroaggregation in binary particle mixtures was simulated with a discrete population balance model in terms of two internal coordinates describing the particle properties. The considered particle species are of different size and zeta-potential. Property space is reduced with a semi-heuristic approach to enable an efficient solution. Aggregation rates are based on deterministic models for Brownian motion and stability, under consideration of DLVO interaction potentials. A charge-balance kernel is presented, relating the electrostatic surface potential to the property space by a simple charge balance. Parameter sensitivity with respect to the fractal dimension, aggregate size, hydrodynamic correction, ionic strength and absolute particle concentration was assessed. Results were compared to simulations with the literature kernel based on geometric coverage effects for clusters with heterogeneous surface properties. In both cases electrostatic phenomena, which dominate the aggregation process, show identical trends: impeded cluster-cluster aggregation at low particle mixing ratio (1:1), restabilisation at high mixing ratios (100:1) and formation of complex clusters for intermediate ratios (10:1). The particle mixing ratio controls the surface coverage extent of the larger particle species. Simulation results are compared to experimental flow cytometric data and show very satisfactory agreement.

  14. Bayesian modeling of recombination events in bacterial populations

    Directory of Open Access Journals (Sweden)

    Dowson Chris

    2008-10-01

    Full Text Available Abstract Background We consider the discovery of recombinant segments jointly with their origins within multilocus DNA sequences from bacteria representing heterogeneous populations of fairly closely related species. The currently available methods for recombination detection capable of probabilistic characterization of uncertainty have a limited applicability in practice as the number of strains in a data set increases. Results We introduce a Bayesian spatial structural model representing the continuum of origins over sites within the observed sequences, including a probabilistic characterization of uncertainty related to the origin of any particular site. To enable a statistically accurate and practically feasible approach to the analysis of large-scale data sets representing a single genus, we have developed a novel software tool (BRAT, Bayesian Recombination Tracker implementing the model and the corresponding learning algorithm, which is capable of identifying the posterior optimal structure and to estimate the marginal posterior probabilities of putative origins over the sites. Conclusion A multitude of challenging simulation scenarios and an analysis of real data from seven housekeeping genes of 120 strains of genus Burkholderia are used to illustrate the possibilities offered by our approach. The software is freely available for download at URL http://web.abo.fi/fak/mnf//mate/jc/software/brat.html.

  15. A sustainable business model for Open-Access journal publishing: a proposed plan for High-Energy Physics

    Directory of Open Access Journals (Sweden)

    Jens Vigen

    2008-01-01

    Full Text Available The High Energy Physics community over the last 15 years has achieved so-called full green Open Access through the wide dissemination of preprints via arXiv, a central subject repository managed by Cornell University. However, green Open Access does not alleviate the economic difficulties of libraries as they are still expected to offer access to versions of record of the peer-reviewed literature. For this reason the particle physics community is now addressing the issue of gold Open Access by converting a set of the existing core journals to Open Access. A Working Party has been established to bring together funding agencies, laboratories and libraries into a single consortium, called SCOAP3 (Sponsoring Consortium for Open Access Publishing in Particle Physics. This consortium will engage with publishers to build a sustainable model for Open Access publishing. In this model, subscription fees from multiple institutions are replaced by contracts with publishers of Open Access journals, where the SCOAP3 consortium is a single financial partner.

  16. A dynamic urban air pollution population exposure assessment study using model and population density data derived by mobile phone traffic

    Science.gov (United States)

    Gariazzo, Claudio; Pelliccioni, Armando; Bolignano, Andrea

    2016-04-01

    A dynamic city-wide air pollution exposure assessment study has been carried out for the urban population of Rome, Italy, by using time resolved population distribution maps, derived by mobile phone traffic data, and modelled air pollutants (NO2, O3 and PM2.5) concentrations obtained by an integrated air dispersion modelling system. More than a million of persons were tracked during two months (March and April 2015) for their position within the city and its surroundings areas, with a time resolution of 15 min and mapped over an irregular grid system with a minimum resolution of 0.26 × 0.34 Km2. In addition, demographics information (as gender and age ranges) were available in a separated dataset not connected with the total population one. Such BigData were matched in time and space with air pollution model results and then used to produce hourly and daily resolved cumulative population exposures during the studied period. A significant mobility of population was identified with higher population densities in downtown areas during daytime increasing of up to 1000 people/Km2 with respect to nigh-time one, likely produced by commuters, tourists and working age population. Strong variability (up to ±50% for NO2) of population exposures were detected as an effect of both mobility and time/spatial changing in pollutants concentrations. A comparison with the correspondent stationary approach based on National Census data, allows detecting the inability of latter in estimating the actual variability of population exposure. Significant underestimations of the amount of population exposed to daily PM2.5 WHO guideline was identified for the Census approach. Very small differences (up to a few μg/m3) on exposure were detected for gender and age ranges population classes.

  17. Using geographical information systems to identify populations in need of improved accessibility to antivenom treatment for snakebite envenoming in Costa Rica.

    Directory of Open Access Journals (Sweden)

    Erik Hansson

    Full Text Available INTRODUCTION: Snakebite accidents are an important health problem in rural areas of tropical countries worldwide, including Costa Rica, where most bites are caused by the pit-viper Bothrops asper. The treatment of these potentially fatal accidents is based on the timely administration of specific antivenom. In many regions of the world, insufficient health care systems and lack of antivenom in remote and poor areas where snakebites are common, means that efficient treatment is unavailable for many snakebite victims, leading to unnecessary mortality and morbidity. In this study, geographical information systems (GIS were used to identify populations in Costa Rica with a need of improved access to antivenom treatment: those living in areas with a high risk of snakebites and long time to reach antivenom treatment. METHOD/PRINCIPAL FINDINGS: Populations living in areas with high risk of snakebites were identified using two approaches: one based on the district-level reported incidence, and another based on mapping environmental factors favoring B. asper presence. Time to reach treatment using ambulance was estimated using cost surface analysis, thereby enabling adjustment of transportation speed by road availability and quality, topography and land use. By mapping populations in high risk of snakebites and the estimated time to treatment, populations with need of improved treatment access were identified. CONCLUSION/SIGNIFICANCE: This study demonstrates the usefulness of GIS for improving treatment of snakebites. By mapping reported incidence, risk factors, location of existing treatment resources, and the time estimated to reach these for at-risk populations, rational allocation of treatment resources is facilitated.

  18. The Chinese electricity access model for rural electrification: Approach, experience and lessons for others

    International Nuclear Information System (INIS)

    Bhattacharyya, Subhes C.; Ohiare, Sanusi

    2012-01-01

    The economic and infrastructural disparities between the rural and urban communities of most developing countries in general and in terms of energy access in particular are quite glaring. China presents a good example of a developing country that has successfully embarked on rural electrification projects over the last few decades and achieved a great feat of almost 100% electrification rate (. World Energy Outlook, 2009, International Energy Agency, Paris (see IEA website at (http://www.worldenergyoutlook.org/electricity.asp).)). The purpose of this paper is to find out how China has achieved this feat; how China’s rural energy projects were financed and whether China provides lessons for other countries to follow. The above questions are examined through an extensive literature review and the paper finds that unlike many other countries following the top-down approach to rural electrification, China has preferred to use a phased development through a bottom-up approach where local resources, and village level development and empowerment played an important role. While the state provided the overall guidance and financial support, the integrated rural development approach has produced local-level solutions that are subsequently integrated to produce an alternative development pathway. Strong government commitment, active local participation, technological flexibility and diversity, strong emphasis on rural development through agricultural and industrial activities and an emphasis on capacity building and training have also played an important role in the success. However, despite achieving the universal access objective, China still faces a number of issues related to rural electricity use, especially in terms of regional use patterns, long-term sustainability of supply and commercial operation of the systems. The Chinese model could serve as an inspiration for other developing countries trying to ensure universal electricity access. - Highlights: ► It

  19. Population dynamics model for plasmid bearing and plasmid lacking ...

    African Journals Online (AJOL)

    Streptokinase production in bioreactor is well associated to cell population dynamics. It is an established fact that two types of cell populations are found to emerge from the initial pool of recombinant cell population. This phenomenon leads to an undesired loss in yield of the product. Primary metabolites, like acetic acid etc ...

  20. [Application of Fourier amplitude sensitivity test in Chinese healthy volunteer population pharmacokinetic model of tacrolimus].

    Science.gov (United States)

    Guan, Zheng; Zhang, Guan-min; Ma, Ping; Liu, Li-hong; Zhou, Tian-yan; Lu, Wei

    2010-07-01

    In this study, we evaluated the influence of different variance from each of the parameters on the output of tacrolimus population pharmacokinetic (PopPK) model in Chinese healthy volunteers, using Fourier amplitude sensitivity test (FAST). Besides, we estimated the index of sensitivity within whole course of blood sampling, designed different sampling times, and evaluated the quality of parameters' and the efficiency of prediction. It was observed that besides CL1/F, the index of sensitivity for all of the other four parameters (V1/F, V2/F, CL2/F and k(a)) in tacrolimus PopPK model showed relatively high level and changed fast with the time passing. With the increase of the variance of k(a), its indices of sensitivity increased obviously, associated with significant decrease in sensitivity index for the other parameters, and obvious change in peak time as well. According to the simulation of NONMEM and the comparison among different fitting results, we found that the sampling time points designed according to FAST surpassed the other time points. It suggests that FAST can access the sensitivities of model parameters effectively, and assist the design of clinical sampling times and the construction of PopPK model.

  1. The climate4impact platform: Providing, tailoring and facilitating climate model data access

    Science.gov (United States)

    Pagé, Christian; Pagani, Andrea; Plieger, Maarten; Som de Cerff, Wim; Mihajlovski, Andrej; de Vreede, Ernst; Spinuso, Alessandro; Hutjes, Ronald; de Jong, Fokke; Bärring, Lars; Vega, Manuel; Cofiño, Antonio; d'Anca, Alessandro; Fiore, Sandro; Kolax, Michael

    2017-04-01

    One of the main objectives of climate4impact is to provide standardized web services and tools that are reusable in other portals. These services include web processing services, web coverage services and web mapping services (WPS, WCS and WMS). Tailored portals can be targeted to specific communities and/or countries/regions while making use of those services. Easier access to climate data is very important for the climate change impact communities. To fulfill this objective, the climate4impact (http://climate4impact.eu/) web portal and services has been developed, targeting climate change impact modellers, impact and adaptation consultants, as well as other experts using climate change data. It provides to users harmonized access to climate model data through tailored services. It features static and dynamic documentation, Use Cases and best practice examples, an advanced search interface, an integrated authentication and authorization system with the Earth System Grid Federation (ESGF), a visualization interface with ADAGUC web mapping tools. In the latest version, statistical downscaling services, provided by the Santander Meteorology Group Downscaling Portal, were integrated. An innovative interface to integrate statistical downscaling services will be released in the upcoming version. The latter will be a big step in bridging the gap between climate scientists and the climate change impact communities. The climate4impact portal builds on the infrastructure of an international distributed database that has been set to disseminate the results from the global climate model results of the Coupled Model Intercomparison project Phase 5 (CMIP5). This database, the ESGF, is an international collaboration that develops, deploys and maintains software infrastructure for the management, dissemination, and analysis of climate model data. The European FP7 project IS-ENES, Infrastructure for the European Network for Earth System modelling, supports the European

  2. Progress towards the child mortality millennium development goal in urban sub-Saharan Africa: the dynamics of population growth, immunization, and access to clean water.

    Science.gov (United States)

    Fotso, Jean-Christophe; Ezeh, Alex Chika; Madise, Nyovani Janet; Ciera, James

    2007-08-28

    Improvements in child survival have been very poor in sub-Saharan Africa (SSA). Since the 1990 s, declines in child mortality have reversed in many countries in the region, while in others, they have either slowed or stalled, making it improbable that the target of reducing child mortality by two thirds by 2015 will be reached. This paper highlights the implications of urban population growth and access to health and social services on progress in achieving MDG 4. Specifically, it examines trends in childhood mortality in SSA in relation to urban population growth, vaccination coverage and access to safe drinking water. Correlation methods are used to analyze national-level data from the Demographic and Health Surveys and from the United Nations. The analysis is complemented by case studies on intra-urban health differences in Kenya and Zambia. Only five of the 22 countries included in the study have recorded declines in urban child mortality that are in line with the MDG target of about 4% per year; five others have recorded an increase; and the 12 remaining countries witnessed only minimal decline. More rapid rate of urban population growth is associated with negative trend in access to safe drinking water and in vaccination coverage, and ultimately to increasing or timid declines in child mortality. There is evidence of intra-urban disparities in child health in some countries like Kenya and Zambia. Failing to appropriately target the growing sub-group of the urban poor and improve their living conditions and health status - which is an MDG target itself - may result in lack of improvement on national indicators of health. Sustained expansion of potable water supplies and vaccination coverage among the disadvantaged urban dwellers should be given priority in the efforts to achieve the child mortality MDG in SSA.

  3. Progress towards the child mortality millennium development goal in urban sub-Saharan Africa: the dynamics of population growth, immunization, and access to clean water

    Directory of Open Access Journals (Sweden)

    Madise Nyovani

    2007-08-01

    Full Text Available Abstract Background Improvements in child survival have been very poor in sub-Saharan Africa (SSA. Since the 1990s, declines in child mortality have reversed in many countries in the region, while in others, they have either slowed or stalled, making it improbable that the target of reducing child mortality by two thirds by 2015 will be reached. This paper highlights the implications of urban population growth and access to health and social services on progress in achieving MDG 4. Specifically, it examines trends in childhood mortality in SSA in relation to urban population growth, vaccination coverage and access to safe drinking water. Methods Correlation methods are used to analyze national-level data from the Demographic and Health Surveys and from the United Nations. The analysis is complemented by case studies on intra-urban health differences in Kenya and Zambia. Results Only five of the 22 countries included in the study have recorded declines in urban child mortality that are in line with the MDG target of about 4% per year; five others have recorded an increase; and the 12 remaining countries witnessed only minimal decline. More rapid rate of urban population growth is associated with negative trend in access to safe drinking water and in vaccination coverage, and ultimately to increasing or timid declines in child mortality. There is evidence of intra-urban disparities in child health in some countries like Kenya and Zambia. Conclusion Failing to appropriately target the growing sub-group of the urban poor and improve their living conditions and health status – which is an MDG target itself – may result in lack of improvement on national indicators of health. Sustained expansion of potable water supplies and vaccination coverage among the disadvantaged urban dwellers should be given priority in the efforts to achieve the child mortality MDG in SSA.

  4. Culturally Diverse and Underserved Populations of Gifted Students in the United States and in Taiwan: Equitable Access to Gifted Education

    Science.gov (United States)

    Ho, Ya-Ting

    2014-01-01

    There is a continuing increase in the African American and Hispanic student populations in public schools. The students who are invited to gifted programs are overwhelmingly White. This is the situation in schools in the United States and also in Taiwan. Misunderstanding or unawareness of culture difference among educators might contribute to…

  5. Improving Access to Primary Care for a Growing Latino Population: The Role of Safety Net Providers in the Rural Midwest

    Science.gov (United States)

    Blewett, Lynn A.; Casey, Michelle; Call, Kathleen Thiede

    2004-01-01

    Many rural Midwestern communities are experiencing rapid growth in Latino populations with low rates of health insurance coverage, limited financial resources, language and cultural differences, and special health care needs. We report on 2-day site visits conducted in 2001 and 2002 in 3 communities (Marshalltown, Iowa; Great Bend, Kansas; and…

  6. Mapping populations at risk: improving spatial demographic data for infectious disease modeling and metric derivation

    Directory of Open Access Journals (Sweden)

    Tatem Andrew J

    2012-05-01

    Full Text Available Abstract The use of Global Positioning Systems (GPS and Geographical Information Systems (GIS in disease surveys and reporting is becoming increasingly routine, enabling a better understanding of spatial epidemiology and the improvement of surveillance and control strategies. In turn, the greater availability of spatially referenced epidemiological data is driving the rapid expansion of disease mapping and spatial modeling methods, which are becoming increasingly detailed and sophisticated, with rigorous handling of uncertainties. This expansion has, however, not been matched by advancements in the development of spatial datasets of human population distribution that accompany disease maps or spatial models. Where risks are heterogeneous across population groups or space or dependent on transmission between individuals, spatial data on human population distributions and demographic structures are required to estimate infectious disease risks, burdens, and dynamics. The disease impact in terms of morbidity, mortality, and speed of spread varies substantially with demographic profiles, so that identifying the most exposed or affected populations becomes a key aspect of planning and targeting interventions. Subnational breakdowns of population counts by age and sex are routinely collected during national censuses and maintained in finer detail within microcensus data. Moreover, demographic and health surveys continue to collect representative and contemporary samples from clusters of communities in low-income countries where census data may be less detailed and not collected regularly. Together, these freely available datasets form a rich resource for quantifying and understanding the spatial variations in the sizes and distributions of those most at risk of disease in low income regions, yet at present, they remain unconnected data scattered across national statistical offices and websites. In this paper we discuss the deficiencies of existing

  7. Improving access in gastroenterology: The single point of entry model for referrals

    Science.gov (United States)

    Novak, Kerri L; Van Zanten, Sander Veldhuyzen; Pendharkar, Sachin R

    2013-01-01

    In 2005, a group of academic gastroenterologists in Calgary (Alberta) adopted a centralized referral intake system known as central triage. This system provided a single point of entry model (SEM) for referrals rather than the traditional system of individual practitioners managing their own referrals and queues. The goal of central triage was to improve wait times and referral management. In 2008, a similar system was developed in Edmonton at the University of Alberta Hospital (Edmonton, Alberta). SEMs have subsequently been adopted by numerous subspecialties throughout Alberta. There are many benefits of SEMs including improved access and reduced wait times. Understanding and measuring complex patient flow systems is key to improving access, and centralized intake systems provide an opportunity to better understand total demand and system bottlenecks. This knowledge is particularly important for specialties such as gastroenterology (GI), in which demand exceeds supply. While it is anticipated that SEMs will reduce wait times for GI care in Canada, the lack of sufficient resources to meet the demand for GI care necessitates additional strategies. PMID:24040629

  8. Editorial: Models, technologies and approaches toward widening the open access to learning and education

    Directory of Open Access Journals (Sweden)

    Rachid Benlamri

    2016-03-01

    Full Text Available This special issue is devoted to novel models and technologies as well as current methodical approaches and best practices in the field of Open Learning and Open Education as enablers of personal growth, social inclusion, open innovation, and sustainable economic development in the challenging conditions of globalization and world-wide competition in productivity and services. The Open Access to Learning and Education embraces not only various technologies, such as mobile and intelligent technologies, content and data management, user-centered design, but also diverse directions of use, such as e-learning and training, organizational development, Massive Open Online Courses, special needs education, all building an excellent basis for various educational and business arrangements that widen the learning and education opportunities for all people around the globe. Against this background, this special issue demonstrates the immense speed and relentlessness of the Open Access concept growth presenting a wide range of examples toward supporting competency and skills development to ensure highly capable human capital, and solve individual, business, urban, demographic, health as well as social inclusion issues in today’s highly demanding digital economy environment.

  9. Construct Validity of Fresh Frozen Human Cadaver as a Training Model in Minimal Access Surgery

    Science.gov (United States)

    Macafee, David; Pranesh, Nagarajan; Horgan, Alan F.

    2012-01-01

    Background: The construct validity of fresh human cadaver as a training tool has not been established previously. The aims of this study were to investigate the construct validity of fresh frozen human cadaver as a method of training in minimal access surgery and determine if novices can be rapidly trained using this model to a safe level of performance. Methods: Junior surgical trainees, novices (cadavers. Expert laparoscopists (>100 laparoscopic procedures) performed 3 repetitions of identical tasks. Performances were scored using a validated, objective Global Operative Assessment of Laparoscopic Skills scale. Scores for 3 consecutive repetitions were compared between experts and novices to determine construct validity. Furthermore, to determine if the novices reached a safe level, a trimmed mean of the experts score was used to define a benchmark. Mann-Whitney U test was used for construct validity analysis and 1-sample t test to compare performances of the novice group with the benchmark safe score. Results: Ten novices and 2 experts were recruited. Four out of 5 tasks (nondominant to dominant hand transfer; simulated appendicectomy; intracorporeal and extracorporeal knot tying) showed construct validity. Novices’ scores became comparable to benchmark scores between the eighth and tenth repetition. Conclusion: Minimal access surgical training using fresh frozen human cadavers appears to have construct validity. The laparoscopic skills of novices can be accelerated through to a safe level within 8 to 10 repetitions. PMID:23318058

  10. Modelling and Analysing Access Control Policies in XACML 3.0

    DEFF Research Database (Denmark)

    Ramli, Carroline Dewi Puspa Kencana

    (c.f. GM03,Mos05,Ris13) and manual analysis of the overall effect and consequences of a large XACML policy set is a very daunting and time-consuming task. In this thesis we address the problem of understanding the semantics of access control policy language XACML, in particular XACML version 3.0....... The main focus of this thesis is modelling and analysing access control policies in XACML 3.0. There are two main contributions in this thesis. First, we study and formalise XACML 3.0, in particular the Policy Decision Point (PDP). The concrete syntax of XACML is based on the XML format, while its standard...... semantics is described normatively using natural language. The use of English text in standardisation leads to the risk of misinterpretation and ambiguity. In order to avoid this drawback, we define an abstract syntax of XACML 3.0 and a formal XACML semantics. Second, we propose a logic-based XACML analysis...

  11. Improving Access in Gastroenterology: The Single Point of Entry Model for Referrals

    Directory of Open Access Journals (Sweden)

    Kerri L Novak

    2013-01-01

    Full Text Available In 2005, a group of academic gastroenterologists in Calgary (Alberta adopted a centralized referral intake system known as central triage. This system provided a single point of entry model (SEM for referrals rather than the traditional system of individual practitioners managing their own referrals and queues. The goal of central triage was to improve wait times and referral management. In 2008, a similar system was developed in Edmonton at the University of Alberta Hospital (Edmonton, Alberta. SEMs have subsequently been adopted by numerous subspecialties throughout Alberta. There are many benefits of SEMs including improved access and reduced wait times. Understanding and measuring complex patient flow systems is key to improving access, and centralized intake systems provide an opportunity to better understand total demand and system bottlenecks. This knowledge is particularly important for specialties such as gastroenterology (GI, in which demand exceeds supply. While it is anticipated that SEMs will reduce wait times for GI care in Canada, the lack of sufficient resources to meet the demand for GI care necessitates additional strategies.

  12. Improving access in gastroenterology: the single point of entry model for referrals.

    Science.gov (United States)

    Novak, Kerri; Veldhuyzen Van Zanten, Sander; Pendharkar, Sachin R

    2013-11-01

    In 2005, a group of academic gastroenterologists in Calgary (Alberta) adopted a centralized referral intake system known as central triage. This system provided a single point of entry model (SEM) for referrals rather than the traditional system of individual practitioners managing their own referrals and queues. The goal of central triage was to improve wait times and referral management. In 2008, a similar system was developed in Edmonton at the University of Alberta Hospital (Edmonton, Alberta). SEMs have subsequently been adopted by numerous subspecialties throughout Alberta. There are many benefits of SEMs including improved access and reduced wait times. Understanding and measuring complex patient flow systems is key to improving access, and centralized intake systems provide an opportunity to better understand total demand and system bottlenecks. This knowledge is particularly important for specialties such as gastroenterology (GI), in which demand exceeds supply. While it is anticipated that SEMs will reduce wait times for GI care in Canada, the lack of sufficient resources to meet the demand for GI care necessitates additional strategies.

  13. Improved population balance model for straining-dominant deep bed filtration using network calculations

    DEFF Research Database (Denmark)

    Yuan, Hao; You, Zhenjiang; Shapiro, Alexander

    2013-01-01

    Colloidal-suspension flow in porous media is modelled simultaneously by the large scale population balance equations and by the microscale network model. The phenomenological parameter of the correlation length in the population balance model is determined from the network modelling. It is found...... out that the correlation length in the population balance model depends on the particle size. This dependency calculated by two-dimensional network has the same tendency as that obtained from the laboratory tests in engineered porous media....

  14. Accessing key steps of human tumor progression in vivo by using an avian embryo model

    Science.gov (United States)

    Hagedorn, Martin; Javerzat, Sophie; Gilges, Delphine; Meyre, Aurélie; de Lafarge, Benjamin; Eichmann, Anne; Bikfalvi, Andreas

    2005-02-01

    Experimental in vivo tumor models are essential for comprehending the dynamic process of human cancer progression, identifying therapeutic targets, and evaluating antitumor drugs. However, current rodent models are limited by high costs, long experimental duration, variability, restricted accessibility to the tumor, and major ethical concerns. To avoid these shortcomings, we investigated whether tumor growth on the chick chorio-allantoic membrane after human glioblastoma cell grafting would replicate characteristics of the human disease. Avascular tumors consistently formed within 2 days, then progressed through vascular endothelial growth factor receptor 2-dependent angiogenesis, associated with hemorrhage, necrosis, and peritumoral edema. Blocking of vascular endothelial growth factor receptor 2 and platelet-derived growth factor receptor signaling pathways by using small-molecule receptor tyrosine kinase inhibitors abrogated tumor development. Gene regulation during the angiogenic switch was analyzed by oligonucleotide microarrays. Defined sample selection for gene profiling permitted identification of regulated genes whose functions are associated mainly with tumor vascularization and growth. Furthermore, expression of known tumor progression genes identified in the screen (IL-6 and cysteine-rich angiogenic inducer 61) as well as potential regulators (lumican and F-box-only 6) follow similar patterns in patient glioma. The model reliably simulates key features of human glioma growth in a few days and thus could considerably increase the speed and efficacy of research on human tumor progression and preclinical drug screening. angiogenesis | animal model alternatives | glioblastoma

  15. Evaluation of the ACCESS – chemistry–climate model for the Southern Hemisphere

    Directory of Open Access Journals (Sweden)

    K. A. Stone

    2016-02-01

    Full Text Available Chemistry–climate models are important tools for addressing interactions of composition and climate in the Earth system. In particular, they are used to assess the combined roles of greenhouse gases and ozone in Southern Hemisphere climate and weather. Here we present an evaluation of the Australian Community Climate and Earth System Simulator – chemistry–climate model (ACCESS-CCM, focusing on the Southern Hemisphere and the Australian region. This model is used for the Australian contribution to the international Chemistry–Climate Model Initiative, which is soliciting hindcast, future projection and sensitivity simulations. The model simulates global total column ozone (TCO distributions accurately, with a slight delay in the onset and recovery of springtime Antarctic ozone depletion, and consistently higher ozone values. However, October-averaged Antarctic TCO from 1960 to 2010 shows a similar amount of depletion compared to observations. Comparison with model precursors shows large improvements in the representation of the Southern Hemisphere stratosphere, especially in TCO concentrations. A significant innovation is seen in the evaluation of simulated vertical profiles of ozone and temperature with ozonesonde data from Australia, New Zealand and Antarctica from 38 to 90° S. Excess ozone concentrations (greater than 26 % at Davis and the South Pole during winter and stratospheric cold biases (up to 10 K at the South Pole during summer and autumn outside the period of perturbed springtime ozone depletion are seen during all seasons compared to ozonesondes. A disparity in the vertical location of ozone depletion is seen: centred around 100 hPa in ozonesonde data compared to above 50 hPa in the model. Analysis of vertical chlorine monoxide profiles indicates that colder Antarctic stratospheric temperatures (possibly due to reduced mid-latitude heat flux are artificially enhancing polar stratospheric cloud formation at high altitudes

  16. Data-driven modelling of structured populations a practical guide to the integral projection model

    CERN Document Server

    Ellner, Stephen P; Rees, Mark

    2016-01-01

    This book is a “How To” guide for modeling population dynamics using Integral Projection Models (IPM) starting from observational data. It is written by a leading research team in this area and includes code in the R language (in the text and online) to carry out all computations. The intended audience are ecologists, evolutionary biologists, and mathematical biologists interested in developing data-driven models for animal and plant populations. IPMs may seem hard as they involve integrals. The aim of this book is to demystify IPMs, so they become the model of choice for populations structured by size or other continuously varying traits. The book uses real examples of increasing complexity to show how the life-cycle of the study organism naturally leads to the appropriate statistical analysis, which leads directly to the IPM itself. A wide range of model types and analyses are presented, including model construction, computational methods, and the underlying theory, with the more technical material in B...

  17. Quantitative estimation of the cost of parasitic castration in a Helisoma anceps population using a matrix population model.

    Science.gov (United States)

    Negovetich, N J; Esch, G W

    2008-10-01

    Larval trematodes frequently castrate their snail intermediate hosts. When castrated, the snails do not contribute offspring to the population, yet they persist and compete with the uninfected individuals for the available food resources. Parasitic castration should reduce the population growth rate lambda, but the magnitude of this decrease is unknown. The present study attempted to quantify the cost of parasitic castration at the level of the population by mathematically modeling the population of the planorbid snail Helisoma anceps in Charlie's Pond, North Carolina. Analysis of the model identified the life-history trait that most affects lambda, and the degree to which parasitic castration can lower lambda. A period matrix product model was constructed with estimates of fecundity, survival, growth rates, and infection probabilities calculated in a previous study. Elasticity analysis was performed by increasing the values of the life-history traits by 10% and recording the percentage change in lambda. Parasitic castration resulted in a 40% decrease in lambda of H. anceps. Analysis of the model suggests that decreasing the size at maturity was more effective at reducing the cost of castration than increasing survival or growth rates of the snails. The current matrix model was the first to mathematically describe a snail population, and the predictions of the model are in agreement with published research.

  18. A demographic model to predict future growth of the Addo elephant population

    Directory of Open Access Journals (Sweden)

    A.M. Woodd

    1999-07-01

    Full Text Available An age-structured demographic model of the growth of the Addo elephant population was developed using parameters calculated from long-term data on the population. The model was used to provide estimates of future population growth. Expansion of the Addo Elephant National Park is currently underway, and the proposed target population size for elephant within the enlarged park is 2700. The model predicts that this population size will be reached during the year 2043, so that the Addo elephant population can continue to increase for a further 44 years before its target size within the enlarged park is attained.

  19. Accessing National Water Model Output for Research and Application: An R package

    Science.gov (United States)

    Johnson, M.; Coll, J.

    2017-12-01

    With the National Water Model becoming operational in August of 2016, the need for a open source way to translate a huge amount of data into actionable intelligence and innovative research is apparent. The first step in doing this is to provide a package for accessing, managing, and writing data in a way that is both interpretable, portable, and useful to the end user in both the R environment, and other applications. This can be as simple as subsetting the outputs and writing to a CSV, but can also include converting discharge output to more meaningful statistics and measurements, and methods to visualize data in ways that are meaningful to a wider audience. The NWM R package presented here aims to serve this need through a suite of functions fit for researchers, first responders, and average citizens. A vignette of how this package can be applied to real-time flood mapping will be demonstrated.

  20. Hemodialysis Reliable Outflow (HeRO) device in end-stage dialysis access: a decision analysis model.

    Science.gov (United States)

    Dageforde, Leigh Anne; Bream, Peter R; Moore, Derek E

    2012-09-01

    The Hemodialysis Reliable Outflow (HeRO) dialysis access device is a permanent tunneled dialysis graft connected to a central venous catheter and is used in patients with end-stage dialysis access (ESDA) issues secondary to central venous stenosis. The safety and effectiveness of the HeRO device has previously been proven, but no study thus far has compared the cost of its use with tunneled dialysis catheters (TDCs) and thigh grafts in patients with ESDA. A decision analytic model was developed to simulate outcomes for patients with ESDA undergoing placement of a HeRO dialysis access device, TDC, or thigh graft. Outcomes of interest were infection, thrombosis, and ischemic events. Baseline values, ranges, and costs were determined from a systematic review of the literature. Total costs were based on 1 year of post-procedure outcomes. Sensitivity analyses were conducted to test model strength. The HeRO dialysis access device is the least costly dialysis access with an average 1-year cost of $6521. The 1-year cost for a TDC was $8477. A thigh graft accounted for $9567 in a 1-year time period. The HeRO dialysis access device is the least costly method of ESDA. The primary determinants of cost in this model are infection in TDCs and leg ischemia necessitating amputation in thigh grafts. Further study is necessary to incorporate patient preference and quality of life into the model. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Single bumps in a 2-population homogenized neuronal network model

    Science.gov (United States)

    Kolodina, Karina; Oleynik, Anna; Wyller, John

    2018-05-01

    We investigate existence and stability of single bumps in a homogenized 2-population neural field model, when the firing rate functions are given by the Heaviside function. The model is derived by means of the two-scale convergence technique of Nguetseng in the case of periodic microvariation in the connectivity functions. The connectivity functions are periodically modulated in both the synaptic footprint and in the spatial scale. The bump solutions are constructed by using a pinning function technique for the case where the solutions are independent of the local variable. In the weakly modulated case the generic picture consists of two bumps (one narrow and one broad bump) for each admissible set of threshold values for firing. In addition, a new threshold value regime for existence of bumps is detected. Beyond the weakly modulated regime the number of bumps depends sensitively on the degree of heterogeneity. For the latter case we present a configuration consisting of three coexisting bumps. The linear stability of the bumps is studied by means of the spectral properties of a Fredholm integral operator, block diagonalization of this operator and the Fourier decomposition method. In the weakly modulated regime, one of the bumps is unstable for all relative inhibition times, while the other one is stable for small and moderate values of this parameter. The latter bump becomes unstable as the relative inhibition time exceeds a certain threshold. In the case of the three coexisting bumps detected in the regime of finite degree of heterogeneity, we have at least one stable bump (and maximum two stable bumps) for small and moderate values of the relative inhibition time.

  2. Comparing deep learning models for population screening using chest radiography

    Science.gov (United States)

    Sivaramakrishnan, R.; Antani, Sameer; Candemir, Sema; Xue, Zhiyun; Abuya, Joseph; Kohli, Marc; Alderson, Philip; Thoma, George

    2018-02-01

    According to the World Health Organization (WHO), tuberculosis (TB) remains the most deadly infectious disease in the world. In a 2015 global annual TB report, 1.5 million TB related deaths were reported. The conditions worsened in 2016 with 1.7 million reported deaths and more than 10 million people infected with the disease. Analysis of frontal chest X-rays (CXR) is one of the most popular methods for initial TB screening, however, the method is impacted by the lack of experts for screening chest radiographs. Computer-aided diagnosis (CADx) tools have gained significance because they reduce the human burden in screening and diagnosis, particularly in countries that lack substantial radiology services. State-of-the-art CADx software typically is based on machine learning (ML) approaches that use hand-engineered features, demanding expertise in analyzing the input variances and accounting for the changes in size, background, angle, and position of the region of interest (ROI) on the underlying medical imagery. More automatic Deep Learning (DL) tools have demonstrated promising results in a wide range of ML applications. Convolutional Neural Networks (CNN), a class of DL models, have gained research prominence in image classification, detection, and localization tasks because they are highly scalable and deliver superior results with end-to-end feature extraction and classification. In this study, we evaluated the performance of CNN based DL models for population screening using frontal CXRs. The results demonstrate that pre-trained CNNs are a promising feature extracting tool for medical imagery including the automated diagnosis of TB from chest radiographs but emphasize the importance of large data sets for the most accurate classification.

  3. Cloud-based calculators for fast and reliable access to NOAA's geomagnetic field models

    Science.gov (United States)

    Woods, A.; Nair, M. C.; Boneh, N.; Chulliat, A.

    2017-12-01

    While the Global Positioning System (GPS) provides accurate point locations, it does not provide pointing directions. Therefore, the absolute directional information provided by the Earth's magnetic field is of primary importance for navigation and for the pointing of technical devices such as aircrafts, satellites and lately, mobile phones. The major magnetic sources that affect compass-based navigation are the Earth's core, its magnetized crust and the electric currents in the ionosphere and magnetosphere. NOAA/CIRES Geomagnetism (ngdc.noaa.gov/geomag/) group develops and distributes models that describe all these important sources to aid navigation. Our geomagnetic models are used in variety of platforms including airplanes, ships, submarines and smartphones. While the magnetic field from Earth's core can be described in relatively fewer parameters and is suitable for offline computation, the magnetic sources from Earth's crust, ionosphere and magnetosphere require either significant computational resources or real-time capabilities and are not suitable for offline calculation. This is especially important for small navigational devices or embedded systems, where computational resources are limited. Recognizing the need for a fast and reliable access to our geomagnetic field models, we developed cloud-based application program interfaces (APIs) for NOAA's ionospheric and magnetospheric magnetic field models. In this paper we will describe the need for reliable magnetic calculators, the challenges faced in running geomagnetic field models in the cloud in real-time and the feedback from our user community. We discuss lessons learned harvesting and validating the data which powers our cloud services, as well as our strategies for maintaining near real-time service, including load-balancing, real-time monitoring, and instance cloning. We will also briefly talk about the progress we achieved on NOAA's Big Earth Data Initiative (BEDI) funded project to develop API

  4. CCBuilder 2.0: Powerful and accessible coiled-coil modeling.

    Science.gov (United States)

    Wood, Christopher W; Woolfson, Derek N

    2018-01-01

    The increased availability of user-friendly and accessible computational tools for biomolecular modeling would expand the reach and application of biomolecular engineering and design. For protein modeling, one key challenge is to reduce the complexities of 3D protein folds to sets of parametric equations that nonetheless capture the salient features of these structures accurately. At present, this is possible for a subset of proteins, namely, repeat proteins. The α-helical coiled coil provides one such example, which represents ≈ 3-5% of all known protein-encoding regions of DNA. Coiled coils are bundles of α helices that can be described by a small set of structural parameters. Here we describe how this parametric description can be implemented in an easy-to-use web application, called CCBuilder 2.0, for modeling and optimizing both α-helical coiled coils and polyproline-based collagen triple helices. This has many applications from providing models to aid molecular replacement for X-ray crystallography, in silico model building and engineering of natural and designed protein assemblies, and through to the creation of completely de novo "dark matter" protein structures. CCBuilder 2.0 is available as a web-based application, the code for which is open-source and can be downloaded freely. http://coiledcoils.chm.bris.ac.uk/ccbuilder2. We have created CCBuilder 2.0, an easy to use web-based application that can model structures for a whole class of proteins, the α-helical coiled coil, which is estimated to account for 3-5% of all proteins in nature. CCBuilder 2.0 will be of use to a large number of protein scientists engaged in fundamental studies, such as protein structure determination, through to more-applied research including designing and engineering novel proteins that have potential applications in biotechnology. © 2017 The Authors Protein Science published by Wiley Periodicals, Inc. on behalf of The Protein Society.

  5. Improving access and equity in reducing cardiovascular risk: the Queensland Health model.

    Science.gov (United States)

    Ski, Chantal F; Vale, Margarite J; Bennett, Gary R; Chalmers, Victoria L; McFarlane, Kim; Jelinek, V Michael; Scott, Ian A; Thompson, David R

    2015-02-16

    To measure changes in cardiovascular risk factors among patients with coronary heart disease (CHD) and/or type 2 diabetes enrolled in a centralised statewide coaching program delivered by telephone and mail-out in the public health sector in Queensland. A population-based audit of cardiovascular risk factor data collected prospectively as part of The COACH (Coaching Patients On Achieving Cardiovascular Health) Program (TCP) delivered through Queensland Health's Health Contact Centre. 1962 patients with CHD and 707 patients with type 2 diabetes who completed TCP from 20 February 2009 to 20 June 2013, of whom 145 were Indigenous Australians. Changes in fasting lipids, fasting glucose, glycosylated haemoglobin levels, blood pressure, body weight, body mass index, smoking, alcohol consumption and physical activity, as measured at entry to and completion of the program. Statistically significant improvements in cardiovascular risk factor status, from entry to completion of the program, were found across all biomedical and lifestyle factors in patients with CHD and/or type 2 diabetes. For both diseases, improvements in serum lipids, blood glucose, smoking habit and alcohol consumption combined with increases in physical activity were the most notable findings. Similar differences were found in mean change scores in cardiovascular risk factors between Indigenous and non-Indigenous Queenslanders. A centralised statewide coaching program delivered by telephone and mail-out overcomes obstacles of distance and limited access to health services and facilitates a guideline-concordant decrease in cardiovascular risk.

  6. Perturbation analysis of transient population dynamics using matrix projection models

    DEFF Research Database (Denmark)

    Stott, Iain

    2016-01-01

    Non-stable populations exhibit short-term transient dynamics: size, growth and structure that are unlike predicted long-term asymptotic stable, stationary or equilibrium dynamics. Understanding transient dynamics of non-stable populations is important for designing effective population management...... these methods to know exactly what is being measured. Despite a wealth of existing methods, I identify some areas that would benefit from further development....

  7. Extension of landscape-based population viability models to ecoregional scales for conservation planning

    Science.gov (United States)

    Thomas W. Bonnot; Frank R. III Thompson; Joshua Millspaugh

    2011-01-01

    Landscape-based population models are potentially valuable tools in facilitating conservation planning and actions at large scales. However, such models have rarely been applied at ecoregional scales. We extended landscape-based population models to ecoregional scales for three species of concern in the Central Hardwoods Bird Conservation Region and compared model...

  8. Experiments with mathematical models to simulate hepatitis A population dynamics under different levels of endemicity

    Directory of Open Access Journals (Sweden)

    Mariana Alves de Guimaraens

    Full Text Available Heterogeneous access to sanitation services is a characteristic of communities in Brazil. This heterogeneity leads to different patterns of hepatitis A endemicity: areas with low infection rates have higher probability of outbreaks, and areas with higher infection rates have high prevalence and low risk of outbreaks. Here we develop a mathematical model to study the effect of variable exposure to infection on the epidemiological dynamics of hepatitis A. Differential equations were used to simulate population dynamics and were numerically solved using the software StellaTM. The model uses parameters from serological surveys in the Greater Metropolitan Rio de Janeiro, in areas with different sanitation conditions. Computer simulation experiments show that the range of infection rates observed in these communities are characteristic of high and low levels of hepatitis A endemicity. We also found that the functional relationship between sanitation and exposure to infection is an important component of the model. The analysis of the public health impact of partial sanitation requires a better understanding of this relationship.

  9. Landscape-based population viability models demonstrate importance of strategic conservation planning for birds

    Science.gov (United States)

    Thomas W. Bonnot; Frank R. Thompson; Joshua J. Millspaugh; D. Todd. Jones-Farland

    2013-01-01

    Efforts to conserve regional biodiversity in the face of global climate change, habitat loss and fragmentation will depend on approaches that consider population processes at multiple scales. By combining habitat and demographic modeling, landscape-based population viability models effectively relate small-scale habitat and landscape patterns to regional population...

  10. The PEcAn Project: Accessible Tools for On-demand Ecosystem Modeling

    Science.gov (United States)

    Cowdery, E.; Kooper, R.; LeBauer, D.; Desai, A. R.; Mantooth, J.; Dietze, M.

    2014-12-01

    Ecosystem models play a critical role in understanding the terrestrial biosphere and forecasting changes in the carbon cycle, however current forecasts have considerable uncertainty. The amount of data being collected and produced is increasing on daily basis as we enter the "big data" era, but only a fraction of this data is being used to constrain models. Until we can improve the problems of model accessibility and model-data communication, none of these resources can be used to their full potential. The Predictive Ecosystem Analyzer (PEcAn) is an ecoinformatics toolbox and a set of workflows that wrap around an ecosystem model and manage the flow of information in and out of regional-scale TBMs. Here we present new modules developed in PEcAn to manage the processing of meteorological data, one of the primary driver dependencies for ecosystem models. The module downloads, reads, extracts, and converts meteorological observations to Unidata Climate Forecast (CF) NetCDF community standard, a convention used for most climate forecast and weather models. The module also automates the conversion from NetCDF to model specific formats, including basic merging, gap-filling, and downscaling procedures. PEcAn currently supports tower-based micrometeorological observations at Ameriflux and FluxNET sites, site-level CSV-formatted data, and regional and global reanalysis products such as the North American Regional Reanalysis and CRU-NCEP. The workflow is easily extensible to additional products and processing algorithms.These meteorological workflows have been coupled with the PEcAn web interface and now allow anyone to run multiple ecosystem models for any location on the Earth by simply clicking on an intuitive Google-map based interface. This will allow users to more readily compare models to observations at those sites, leading to better calibration and validation. Current work is extending these workflows to also process field, remotely-sensed, and historical

  11. The EV Project Price/Fee Models for Publicly Accessible Charging

    Energy Technology Data Exchange (ETDEWEB)

    Francfort, James Edward [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-12-01

    As plug-in electric vehicles (PEVs) are introduced to the market place and gain more consumer acceptance, it is important for a robust and self-sustaining non-residential infrastructure of electric vehicle supply equipment (EVSE) to be established to meet the needs of PEV drivers. While federal and state financial incentives for electric vehicles were in place and remain so today, future incentives are uncertain. In order for PEVs to achieve mainstream adoption, an adequate and sustainable commercial or publicly available charging infrastructure was pursued by The EV Project to encourage increased PEV purchases by alleviating range anxiety, and by removing adoption barriers for consumers without a dedicated overnight parking location to provide a home-base charger. This included determining a business model for publicly accessible charge infrastructure. To establish this business model, The EV Project team created a fee for charge model along with various ancillary offerings related to charging that would generate revenue. And after placing chargers in the field the Project rolled out this fee structure.

  12. Approximate reduction of linear population models governed by stochastic differential equations: application to multiregional models.

    Science.gov (United States)

    Sanz, Luis; Alonso, Juan Antonio

    2017-12-01

    In this work we develop approximate aggregation techniques in the context of slow-fast linear population models governed by stochastic differential equations and apply the results to the treatment of populations with spatial heterogeneity. Approximate aggregation techniques allow one to transform a complex system involving many coupled variables and in which there are processes with different time scales, by a simpler reduced model with a fewer number of 'global' variables, in such a way that the dynamics of the former can be approximated by that of the latter. In our model we contemplate a linear fast deterministic process together with a linear slow process in which the parameters are affected by additive noise, and give conditions for the solutions corresponding to positive initial conditions to remain positive for all times. By letting the fast process reach equilibrium we build a reduced system with a lesser number of variables, and provide results relating the asymptotic behaviour of the first- and second-order moments of the population vector for the original and the reduced system. The general technique is illustrated by analysing a multiregional stochastic system in which dispersal is deterministic and the rate growth of the populations in each patch is affected by additive noise.

  13. Hub and spoke model: making rural healthcare in India affordable, available and accessible.

    Science.gov (United States)

    Devarakonda, Srichand

    2016-01-01

    Quality health care should be within everyone's reach, especially in a developing country. While India has the largest private health sector in the world, only one-fifth of healthcare expenditure is publically financed; it is mostly an out-of-pocket expense. About 70% of Indians live in rural areas making about $3 per day, and a major portion of that goes towards food and shelter and, thus, not towards health care. Transportation facilities in rural India are poor, making access to medical facilities difficult, and infrastructure facilities are minimal, making the available medical care insufficient. The challenge presented to India was to provide health care that was accessible, available and affordable to people in rural areas and the low-income bracket. The intent of this article is to determine whether the hub and spoke model (HSM), when implemented in the healthcare industry, can expand the market reach and increase profits while reducing costs of operations for organizations and, thereby, cost to customers. This article also discusses the importance of information and communications technologies (ICT) in the HSM approach, which the handful of published articles in this topic have failed to discuss. This article opts for an exploratory study, including review of published literature, web articles, viewpoints of industry experts, published journals, and in-depth interviews. This article will discuss how and why the HSM works in India's healthcare industry while isolating its strengths and weaknesses, and analyzing the impact of India's success. India's HSM implementation has become a paramount example of an acceptable model that, while exceeding the needs and expectations of its patients, is cost-effective and has obtained operational and health-driven results. Despite being an emerging nation, India takes the top spot in terms of affordability of ICT as well as for having the highest number of computer-literate graduates and healthcare workers in the world

  14. Inequalities in the dental health needs and access to dental services among looked after children in Scotland: a population data linkage study.

    Science.gov (United States)

    McMahon, Alex D; Elliott, Lawrie; Macpherson, Lorna Md; Sharpe, Katharine H; Connelly, Graham; Milligan, Ian; Wilson, Philip; Clark, David; King, Albert; Wood, Rachael; Conway, David I

    2018-01-01

    There is limited evidence on the health needs and service access among children and young people who are looked after by the state. The aim of this study was to compare dental treatment needs and access to dental services (as an exemplar of wider health and well-being concerns) among children and young people who are looked after with the general child population. Population data linkage study utilising national datasets of social work referrals for 'looked after' placements, the Scottish census of children in local authority schools, and national health service's dental health and service datasets. 633 204 children in publicly funded schools in Scotland during the academic year 2011/2012, of whom 10 927 (1.7%) were known to be looked after during that or a previous year (from 2007-2008). The children in the looked after children (LAC) group were more likely to have urgent dental treatment need at 5 years of age: 23%vs10% (n=209/16533), adjusted (for age, sex and area socioeconomic deprivation) OR 2.65 (95% CI 2.30 to 3.05); were less likely to attend a dentist regularly: 51%vs63% (n=5519/388934), 0.55 (0.53 to 0.58) and more likely to have teeth extracted under general anaesthesia: 9%vs5% (n=967/30253), 1.91 (1.78 to 2.04). LAC are more likely to have dental treatment needs and less likely to access dental services even when accounting for sociodemographic factors. Greater efforts are required to integrate child social and healthcare for LAC and to develop preventive care pathways on entering and throughout their time in the care system. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  15. Modeling evolutionary games in populations with demographic structure

    DEFF Research Database (Denmark)

    Li, Xiang-Yi; Giaimo, Stefano; Baudisch, Annette

    2015-01-01

    interactions, but usually omits life history and the demographic structure of the population. Here we show how an integration of both aspects can substantially alter the underlying evolutionary dynamics. We study the replicator dynamics of strategy interactions in life stage structured populations. Individuals...

  16. World population in transition : An integrated regional modelling framework

    NARCIS (Netherlands)

    Hilderink, Henricus Bernardus Maria

    2000-01-01

    The world’s population reached the milestone of 6 billion in 1999 and increases by around 150 persons each minute. In the last few decades, population growth seen in the light of limited natural and economic resources has become of growing concern. Now, at the beginning of a new millennium,

  17. A spatiotemporal optimization model for the evacuation of the population exposed to flood hazard

    Science.gov (United States)

    Alaeddine, H.; Serrhini, K.; Maizia, M.

    2015-03-01

    Managing the crisis caused by natural disasters, and especially by floods, requires the development of effective evacuation systems. An effective evacuation system must take into account certain constraints, including those related to traffic network, accessibility, human resources and material equipment (vehicles, collecting points, etc.). The main objective of this work is to provide assistance to technical services and rescue forces in terms of accessibility by offering itineraries relating to rescue and evacuation of people and property. We consider in this paper the evacuation of an urban area of medium size exposed to the hazard of flood. In case of inundation, most people will be evacuated using their own vehicles. Two evacuation types are addressed in this paper: (1) a preventive evacuation based on a flood forecasting system and (2) an evacuation during the disaster based on flooding scenarios. The two study sites on which the developed evacuation model is applied are the Tours valley (Fr, 37), which is protected by a set of dikes (preventive evacuation), and the Gien valley (Fr, 45), which benefits from a low rate of flooding (evacuation before and during the disaster). Our goal is to construct, for each of these two sites, a chronological evacuation plan, i.e., computing for each individual the departure date and the path to reach the assembly point (also called shelter) according to a priority list established for this purpose. The evacuation plan must avoid the congestion on the road network. Here we present a spatiotemporal optimization model (STOM) dedicated to the evacuation of the population exposed to natural disasters and more specifically to flood risk.

  18. A spatio-temporel optimization model for the evacuation of the population exposed to natural disasters

    Science.gov (United States)

    Alaeddine, H.; Serrhini, K.; Maïzia, M.; Néron, E.

    2015-01-01

    The importance of managing the crisis caused by natural disasters, and especially by flood, requires the development of an effective evacuation systems. An effective evacuation system must take into account certain constraints, including those related to network traffic, accessibility, human resources and material equipment (vehicles, collecting points, etc.). The main objective of this work is to provide assistance to technical services and rescue forces in terms of accessibility by offering itineraries relating to rescue and evacuation of people and property. We consider in this paper the evacuation of an urban area of medium size exposed to the hazard of flood. In case of inundation, most people will be evacuated using their own vehicles. Two evacuation types are addressed in this paper, (1) a preventive evacuation based on a flood forecasting system and (2) an evacuation during the disaster based on flooding scenarios. The two study sites on which the evacuation model developed is applied are the valley of Tours (Fr, 37) which is protected by a set of dikes (preventive evacuation) and the valley of Gien (Fr, 45) which benefits of a low rate of flooding (evacuation before and during the disaster). Our goal is to construct, for each of these two sites, a chronological evacuation plan i.e. computing for each individual the departure date and the path to reach the assembly point (also called shelter) associated according to a priorities list established for this purpose. Evacuation plan must avoid the congestion on the road network. Here we present a Spatio-Temporal Optimization Model (STOM) dedicated to the evacuation of the population exposed to natural disasters and more specifically to flood risk.

  19. Projection of Anthropometric Correlation for Virtual Population Modelling

    DEFF Research Database (Denmark)

    Rasmussen, John; Waagepetersen, Rasmus Plenge; Rasmussen, Kasper Pihl

    2018-01-01

    , and therefore the correlations between parameters, are not accessible. This problem is solved by projecting correlation from a data set for which raw data are provided. The method is tested and validated by generation of pseudo females from males in the ANSUR anthropometric dataset. Results show...

  20. Modelling techniques for predicting the long term consequences of radiation on natural aquatic populations

    International Nuclear Information System (INIS)

    Wallis, I.G.

    1978-01-01

    The purpose of this working paper is to describe modelling techniques for predicting the long term consequences of radiation on natural aquatic populations. Ideally, it would be possible to use aquatic population models: (1) to predict changes in the health and well-being of all aquatic populations as a result of changing the composition, amount and location of radionuclide discharges; (2) to compare the effects of steady, fluctuating and accidental releases of radionuclides; and (3) to evaluate the combined impact of the discharge of radionuclides and other wastes, and natural environmental stresses on aquatic populations. At the onset it should be stated that there is no existing model which can achieve this ideal performance. However, modelling skills and techniques are available to develop useful aquatic population models. This paper discusses the considerations involved in developing these models and briefly describes the various types of population models which have been developed to date

  1. A one-population Amari model with periodic microstructure

    International Nuclear Information System (INIS)

    Svanstedt, Nils; Wyller, John; Malyutina, Elena

    2014-01-01

    We review the derivation of the homogenized one-population Amari equation by means of the two-scale convergence technique of Nguetseng in the case of periodic microvariation in the connectivity function. A key point in this derivation is Visintin's theorem for two-scale convergence of convolution integrals. We construct single bump solutions of the resulting homogenized equation using a pinning function technique for the case where the solutions are independent of the local variable and the firing rate function is modelled as a unit step function. The parameter measuring the degree of heterogeneity plays the role of a control parameter. The connectivity functions are periodically modulated in both the synaptic footprint and in the spatial scale. A framework for analysing the stability of these structures is formulated. This framework is based on spectral theory for Hilbert–Schmidt integral operators and it deforms to the standard Evans function approach for the translational invariant case in the limit of no heterogeneity. The upper and lower bounds of the growth/decay rates of the perturbations imposed on the bump states can be expressed in terms of the operator norm of the actual Hilbert–Schmidt operator. Intervals for which the pinning function is increasing correspond to unstable bumps, while complementary intervals where the pinning function decreases correspond to stable bumps, just as in the translational invariant case. Examples showing the properties of the bumps are discussed in detail when the connectivity kernels are given in terms of an exponential decaying function, a wizard hat function and a damped oscillating function. (paper)

  2. Face Recognition for Access Control Systems Combining Image-Difference Features Based on a Probabilistic Model

    Science.gov (United States)

    Miwa, Shotaro; Kage, Hiroshi; Hirai, Takashi; Sumi, Kazuhiko

    We propose a probabilistic face recognition algorithm for Access Control System(ACS)s. Comparing with existing ACSs using low cost IC-cards, face recognition has advantages in usability and security that it doesn't require people to hold cards over scanners and doesn't accept imposters with authorized cards. Therefore face recognition attracts more interests in security markets than IC-cards. But in security markets where low cost ACSs exist, price competition is important, and there is a limitation on the quality of available cameras and image control. Therefore ACSs using face recognition are required to handle much lower quality images, such as defocused and poor gain-controlled images than high security systems, such as immigration control. To tackle with such image quality problems we developed a face recognition algorithm based on a probabilistic model which combines a variety of image-difference features trained by Real AdaBoost with their prior probability distributions. It enables to evaluate and utilize only reliable features among trained ones during each authentication, and achieve high recognition performance rates. The field evaluation using a pseudo Access Control System installed in our office shows that the proposed system achieves a constant high recognition performance rate independent on face image qualities, that is about four times lower EER (Equal Error Rate) under a variety of image conditions than one without any prior probability distributions. On the other hand using image difference features without any prior probabilities are sensitive to image qualities. We also evaluated PCA, and it has worse, but constant performance rates because of its general optimization on overall data. Comparing with PCA, Real AdaBoost without any prior distribution performs twice better under good image conditions, but degrades to a performance as good as PCA under poor image conditions.

  3. Ability of matrix models to explain the past and predict the future of plant populations.

    Science.gov (United States)

    McEachern, Kathryn; Crone, Elizabeth E.; Ellis, Martha M.; Morris, William F.; Stanley, Amanda; Bell, Timothy; Bierzychudek, Paulette; Ehrlen, Johan; Kaye, Thomas N.; Knight, Tiffany M.; Lesica, Peter; Oostermeijer, Gerard; Quintana-Ascencio, Pedro F.; Ticktin, Tamara; Valverde, Teresa; Williams, Jennifer I.; Doak, Daniel F.; Ganesan, Rengaian; Thorpe, Andrea S.; Menges, Eric S.

    2013-01-01

    Uncertainty associated with ecological forecasts has long been recognized, but forecast accuracy is rarely quantified. We evaluated how well data on 82 populations of 20 species of plants spanning 3 continents explained and predicted plant population dynamics. We parameterized stage-based matrix models with demographic data from individually marked plants and determined how well these models forecast population sizes observed at least 5 years into the future. Simple demographic models forecasted population dynamics poorly; only 40% of observed population sizes fell within our forecasts' 95% confidence limits. However, these models explained population dynamics during the years in which data were collected; observed changes in population size during the data-collection period were strongly positively correlated with population growth rate. Thus, these models are at least a sound way to quantify population status. Poor forecasts were not associated with the number of individual plants or years of data. We tested whether vital rates were density dependent and found both positive and negative density dependence. However, density dependence was not associated with forecast error. Forecast error was significantly associated with environmental differences between the data collection and forecast periods. To forecast population fates, more detailed models, such as those that project how environments are likely to change and how these changes will affect population dynamics, may be needed. Such detailed models are not always feasible. Thus, it may be wiser to make risk-averse decisions than to expect precise forecasts from models.

  4. Ability of matrix models to explain the past and predict the future of plant populations.

    Science.gov (United States)

    Crone, Elizabeth E; Ellis, Martha M; Morris, William F; Stanley, Amanda; Bell, Timothy; Bierzychudek, Paulette; Ehrlén, Johan; Kaye, Thomas N; Knight, Tiffany M; Lesica, Peter; Oostermeijer, Gerard; Quintana-Ascencio, Pedro F; Ticktin, Tamara; Valverde, Teresa; Williams, Jennifer L; Doak, Daniel F; Ganesan, Rengaian; McEachern, Kathyrn; Thorpe, Andrea S; Menges, Eric S

    2013-10-01

    Uncertainty associated with ecological forecasts has long been recognized, but forecast accuracy is rarely quantified. We evaluated how well data on 82 populations of 20 species of plants spanning 3 continents explained and predicted plant population dynamics. We parameterized stage-based matrix models with demographic data from individually marked plants and determined how well these models forecast population sizes observed at least 5 years into the future. Simple demographic models forecasted population dynamics poorly; only 40% of observed population sizes fell within our forecasts' 95% confidence limits. However, these models explained population dynamics during the years in which data were collected; observed changes in population size during the data-collection period were strongly positively correlated with population growth rate. Thus, these models are at least a sound way to quantify population status. Poor forecasts were not associated with the number of individual plants or years of data. We tested whether vital rates were density dependent and found both positive and negative density dependence. However, density dependence was not associated with forecast error. Forecast error was significantly associated with environmental differences between the data collection and forecast periods. To forecast population fates, more detailed models, such as those that project how environments are likely to change and how these changes will affect population dynamics, may be needed. Such detailed models are not always feasible. Thus, it may be wiser to make risk-averse decisions than to expect precise forecasts from models. © 2013 Society for Conservation Biology.

  5. Making interdisciplinary solid Earth modeling and analysis tools accessible in a diverse undergraduate and graduate classroom

    Science.gov (United States)

    Becker, T. W.

    2011-12-01

    I present results from ongoing, NSF-CAREER funded educational and research efforts that center around making numerical tools in seismology and geodynamics more accessible to a broader audience. The goal is not only to train students in quantitative, interdisciplinary research, but also to make methods more easily accessible to practitioners across disciplines. I describe the two main efforts that were funded, the Solid Earth Research and Teaching Environment (SEATREE, geosys.usc.edu/projects/seatree/), and a new Numerical Methods class. SEATREE is a modular and user-friendly software framework to facilitate using solid Earth research tools in the undergraduate and graduate classroom and for interdisciplinary, scientific collaboration. We use only open-source software, and most programming is done in the Python computer language. We strive to make use of modern software design and development concepts while remaining compatible with traditional scientific coding and existing, legacy software. Our goals are to provide a fully contained, yet transparent package that lets users operate in an easy, graphically supported "black box" mode, while also allowing to look under the hood, for example to conduct numerous forward models to explore parameter space. SEATREE currently has several implemented modules, including on global mantle flow, 2D phase velocity tomography, and 2D mantle convection and was used at the University of Southern California, Los Angeles, and at a 2010 CIDER summer school tutorial. SEATREE was developed in collaboration with engineering and computer science undergraduate students, some of which have gone on to work in Earth Science projects. In the long run, we envision SEATREE to contribute to new ways of sharing scientific research, and making (numerical) experiments truly reproducible again. The other project is a set of lecture notes and Matlab exercises on Numerical Methods in solid Earth, focusing on finite difference and element methods. The

  6. Using dynamic stochastic modelling to estimate population risk factors in infectious disease: the example of FIV in 15 cat populations.

    Directory of Open Access Journals (Sweden)

    David Fouchet

    Full Text Available BACKGROUND: In natural cat populations, Feline Immunodeficiency Virus (FIV is transmitted through bites between individuals. Factors such as the density of cats within the population or the sex-ratio can have potentially strong effects on the frequency of fight between individuals and hence appear as important population risk factors for FIV. METHODOLOGY/PRINCIPAL FINDINGS: To study such population risk factors, we present data on FIV prevalence in 15 cat populations in northeastern France. We investigate five key social factors of cat populations; the density of cats, the sex-ratio, the number of males and the mean age of males and females within the population. We overcome the problem of dependence in the infective status data using sexually-structured dynamic stochastic models. Only the age of males and females had an effect (p = 0.043 and p = 0.02, respectively on the male-to-female transmission rate. Due to multiple tests, it is even likely that these effects are, in reality, not significant. Finally we show that, in our study area, the data can be explained by a very simple model that does not invoke any risk factor. CONCLUSION: Our conclusion is that, in host-parasite systems in general, fluctuations due to stochasticity in the transmission process are naturally very large and may alone explain a larger part of the variability in observed disease prevalence between populations than previously expected. Finally, we determined confidence intervals for the simple model parameters that can be used to further aid in management of the disease.

  7. Towards developing a compact model for magnetization switching in straintronics magnetic random access memory devices

    International Nuclear Information System (INIS)

    Barangi, Mahmood; Erementchouk, Mikhail; Mazumder, Pinaki

    2016-01-01

    Strain-mediated magnetization switching in a magnetic tunneling junction (MTJ) by exploiting a combination of piezoelectricity and magnetostriction has been proposed as an energy efficient alternative to spin transfer torque (STT) and field induced magnetization switching methods in MTJ-based magnetic random access memories (MRAM). Theoretical studies have shown the inherent advantages of strain-assisted switching, and the dynamic response of the magnetization has been modeled using the Landau-Lifshitz-Gilbert (LLG) equation. However, an attempt to use LLG for simulating dynamics of individual elements in large-scale simulations of multi-megabyte straintronics MRAM leads to extremely time-consuming calculations. Hence, a compact analytical solution, predicting the flipping delay of the magnetization vector in the nanomagnet under stress, combined with a liberal approximation of the LLG dynamics in the straintronics MTJ, can lead to a simplified model of the device suited for fast large-scale simulations of multi-megabyte straintronics MRAMs. In this work, a tensor-based approach is developed to study the dynamic behavior of the stressed nanomagnet. First, using the developed method, the effect of stress on the switching behavior of the magnetization is investigated to realize the margins between the underdamped and overdamped regimes. The latter helps the designer realize the oscillatory behavior of the magnetization when settling along the minor axis, and the dependency of oscillations on the stress level and the damping factor. Next, a theoretical model to predict the flipping delay of the magnetization vector is developed and tested against LLG-based numerical simulations to confirm the accuracy of findings. Lastly, the obtained delay is incorporated into the approximate solutions of the LLG dynamics, in order to create a compact model to liberally and quickly simulate the magnetization dynamics of the MTJ under stress. Using the developed delay equation, the

  8. Towards developing a compact model for magnetization switching in straintronics magnetic random access memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Barangi, Mahmood, E-mail: barangi@umich.edu; Erementchouk, Mikhail; Mazumder, Pinaki [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2121 (United States)

    2016-08-21

    Strain-mediated magnetization switching in a magnetic tunneling junction (MTJ) by exploiting a combination of piezoelectricity and magnetostriction has been proposed as an energy efficient alternative to spin transfer torque (STT) and field induced magnetization switching methods in MTJ-based magnetic random access memories (MRAM). Theoretical studies have shown the inherent advantages of strain-assisted switching, and the dynamic response of the magnetization has been modeled using the Landau-Lifshitz-Gilbert (LLG) equation. However, an attempt to use LLG for simulating dynamics of individual elements in large-scale simulations of multi-megabyte straintronics MRAM leads to extremely time-consuming calculations. Hence, a compact analytical solution, predicting the flipping delay of the magnetization vector in the nanomagnet under stress, combined with a liberal approximation of the LLG dynamics in the straintronics MTJ, can lead to a simplified model of the device suited for fast large-scale simulations of multi-megabyte straintronics MRAMs. In this work, a tensor-based approach is developed to study the dynamic behavior of the stressed nanomagnet. First, using the developed method, the effect of stress on the switching behavior of the magnetization is investigated to realize the margins between the underdamped and overdamped regimes. The latter helps the designer realize the oscillatory behavior of the magnetization when settling along the minor axis, and the dependency of oscillations on the stress level and the damping factor. Next, a theoretical model to predict the flipping delay of the magnetization vector is developed and tested against LLG-based numerical simulations to confirm the accuracy of findings. Lastly, the obtained delay is incorporated into the approximate solutions of the LLG dynamics, in order to create a compact model to liberally and quickly simulate the magnetization dynamics of the MTJ under stress. Using the developed delay equation, the

  9. An agent-based computational model for tuberculosis spreading on age-structured populations

    Science.gov (United States)

    Graciani Rodrigues, C. C.; Espíndola, Aquino L.; Penna, T. J. P.

    2015-06-01

    In this work we present an agent-based computational model to study the spreading of the tuberculosis (TB) disease on age-structured populations. The model proposed is a merge of two previous models: an agent-based computational model for the spreading of tuberculosis and a bit-string model for biological aging. The combination of TB with the population aging, reproduces the coexistence of health states, as seen in real populations. In addition, the universal exponential behavior of mortalities curves is still preserved. Finally, the population distribution as function of age shows the prevalence of TB mostly in elders, for high efficacy treatments.

  10. Biomedical Big Data: New Models of Control Over Access, Use and Governance.

    Science.gov (United States)

    Vayena, Effy; Blasimme, Alessandro

    2017-12-01

    Empirical evidence suggests that while people hold the capacity to control their data in high regard, they increasingly experience a loss of control over their data in the online world. The capacity to exert control over the generation and flow of personal information is a fundamental premise to important values such as autonomy, privacy, and trust. In healthcare and clinical research this capacity is generally achieved indirectly, by agreeing to specific conditions of informational exposure. Such conditions can be openly stated in informed consent documents or be implicit in the norms of confidentiality that govern the relationships of patients and healthcare professionals. However, with medicine becoming a data-intense enterprise, informed consent and medical confidentiality, as mechanisms of control, are put under pressure. In this paper we explore emerging models of informational control in data-intense healthcare and clinical research, which can compensate for the limitations of currently available instruments. More specifically, we discuss three approaches that hold promise in increasing individual control: the emergence of data portability rights as means to control data access, new mechanisms of informed consent as tools to control data use, and finally, new participatory governance schemes that allow individuals to control their data through direct involvement in data governance. We conclude by suggesting that, despite the impression that biomedical big data diminish individual control, the synergistic effect of new data management models can in fact improve it.

  11. Population viability analysis: using a modeling tool to assess the viability of tapir populations in fragmented landscapes.

    Science.gov (United States)

    Medici, Emília Patrícia; Desbiez, Arnaud Leonard Jean

    2012-12-01

    A population viability analysis (PVA) was conducted of the lowland tapir populations in the Atlantic Forest of the Pontal do Paranapanema region, Brazil, including Morro do Diabo State Park (MDSP) and surrounding forest fragments. Results from the model projected that the population of 126 tapirs in MDSP is likely to persist over the next 100 years; however, 200 tapirs would be required to maintain a viable population. Sensitivity analysis showed that sub-adult mortality and adult mortality have the strongest influence on the dynamics of lowland tapir populations. High road-kill has a major impact on the MDSP tapir population and can lead to population extinction. Metapopulation modeling showed that dispersal of tapirs from MDSP to the surrounding fragments can be detrimental to the overall metapopulation, as fragments act as sinks. Nevertheless, the model showed that under certain conditions the maintenance of the metapopulation dynamics might be determinant for the persistence of tapirs in the region, particularly in the smaller fragments. The establishment of corridors connecting MDSP to the forest fragments models resulted in an increase in the stochastic growth rate, making tapirs more resilient to threats and catastrophes, but only if rates of mortality were not increased when using corridors. The PVA showed that the conservation of tapirs in the Pontal region depends on: the effective protection of MDSP; maintenance and, whenever possible, enhancement of the functional connectivity of the landscape, reducing mortality during dispersal and threats in the unprotected forest fragments; and neutralization of all threats affecting tapirs in the smaller forest fragments. © 2012 Wiley Publishing Asia Pty Ltd, ISZS and IOZ/CAS.

  12. The relative importance of intrinsic and extrinsic drivers to population growth vary among local populations of Greater Sage-Grouse: An integrated population modeling approach

    Science.gov (United States)

    Coates, Peter S.; Prochazka, Brian G.; Ricca, Mark A.; Halstead, Brian J.; Casazza, Michael L.; Blomberg, Erik J.; Brussee, Brianne E.; Wiechman, Lief; Tebbenkamp, Joel; Gardner, Scott C.; Reese, Kerry P.

    2018-01-01

    Consideration of ecological scale is fundamental to understanding and managing avian population growth and decline. Empirically driven models for population dynamics and demographic processes across multiple spatial scales can be powerful tools to help guide conservation actions. Integrated population models (IPMs) provide a framework for better parameter estimation by unifying multiple sources of data (e.g., count and demographic data). Hierarchical structure within such models that include random effects allow for varying degrees of data sharing across different spatiotemporal scales. We developed an IPM to investigate Greater Sage-Grouse (Centrocercus urophasianus) on the border of California and Nevada, known as the Bi-State Distinct Population Segment. Our analysis integrated 13 years of lek count data (n > 2,000) and intensive telemetry (VHF and GPS; n > 350 individuals) data across 6 subpopulations. Specifically, we identified the most parsimonious models among varying random effects and density-dependent terms for each population vital rate (e.g., nest survival). Using a joint likelihood process, we integrated the lek count data with the demographic models to estimate apparent abundance and refine vital rate parameter estimates. To investigate effects of climatic conditions, we extended the model to fit a precipitation covariate for instantaneous rate of change (r). At a metapopulation extent (i.e. Bi-State), annual population rate of change λ (er) did not favor an overall increasing or decreasing trend through the time series. However, annual changes in λ were driven by changes in precipitation (one-year lag effect). At subpopulation extents, we identified substantial variation in λ and demographic rates. One subpopulation clearly decoupled from the trend at the metapopulation extent and exhibited relatively high risk of extinction as a result of low egg fertility. These findings can inform localized, targeted management actions for specific areas

  13. A Model for Trust-based Access Control and Delegation in Mobile Clouds (Post Print)

    Science.gov (United States)

    2013-10-01

    the access-granter knowing the identity of access requester beforehand and authenticating the requester, can no longer be applied. Mobile Wallet Cloud...TktC) for a reservation and con- tacts the user’s mobile wallet provider (MobWC) to purchase the ticket from TktC. For accessing different services...receiving regular services. For example, the human user in our scenario can be an elite member with the mobile wallet service provider that

  14. Modeling Agassiz's Desert Tortoise Population Response to Anthropogenic Stressors

    Science.gov (United States)

    Mojave Desert tortoise (Gopherus agassizii) populations are exposed to a variety of anthropogenic threats, which vary in nature, severity, and frequency. Tortoise management in conservation areas can be compromised when the relative importance of these threats is not well underst...

  15. The importance of the reference populations for coherent mortality forecasting models

    DEFF Research Database (Denmark)

    Kjærgaard, Søren; Canudas-Romo, Vladimir; Vaupel, James W.

    -population mortality models aiming to find the optimal of the set of countries to use as reference population and analyse the importance of the selection of countries. The two multi-population mortality models used are the Li-Lee model and the Double-Gap life expectancy forecasting model. The reference populations......Coherent forecasting models that take into consideration mortality changes observed in different countries are today among the essential tools for demographers, actuaries and other researchers interested in forecasts. Medium and long term life expectancy forecasts are compared for two multi...... is calculated taking into account all the possible combinations of a set of 20 industrialized countries. The different reference populations possibilities are compared by their forecast performance. The results show that the selection of countries for multi-population mortality models has a significant effect...

  16. An estimation model of population in China using time series DMSP night-time satellite imagery from 2002-2010

    Science.gov (United States)

    Zhang, Xiaoyong; Zhang, Zhijie; Chang, Yuguang; Chen, Zhengchao

    2015-12-01

    Accurate data on the spatial distribution and potential growth estimation of human population are playing pivotal role in addressing and mitigating heavy lose caused by earthquake. Traditional demographic data is limited in its spatial resolution and is extremely hard to update. With the accessibility of massive DMSP/OLS night time imagery, it is possible to model population distribution at the county level across China. In order to compare and improve the continuity and consistency of time-series DMSP night-time satellite imagery obtained by different satellites in same year or different years by the same satellite from 2002-2010, normalized method was deployed for the inter-correction among imageries. And we referred to the reference F162007 Jixi city, whose social-economic has been relatively stable. Through binomial model, with average R2 0.90, then derived the correction factor of each year. The normalization obviously improved consistency comparing to previous data, which enhanced the correspondent accuracy of model. Then conducted the model of population density between average night-time light intensity in eight-economic districts. According to the two parameters variation law of consecutive years, established the prediction model of next following years with R2of slope and constant typically 0.85 to 0.95 in different regions. To validate the model, taking the year of 2005 as example, retrieved quantitatively population distribution in per square kilometer based on the model, then compared the results to the statistical data based on census, the difference of the result is acceptable. In summary, the estimation model facilitates the quick estimation and prediction in relieving the damage to people, which is significant in decision-making.

  17. Modeling heterogeneous populations of thermostatically controlled loads using diffusion-advection PDEs

    DEFF Research Database (Denmark)

    Moura, Scott; Ruiz, Victor; Bendtsen, Jan Dimon

    2013-01-01

    This paper focuses on developing a partial differential equation (PDE)-based model and parameter identification scheme for heterogeneous populations of thermostatically controlled loads (TCLs). First, a coupled two-state hyperbolic PDE model for homogenous TCL populations is derived. This model i...

  18. Linking population viability, habitat suitability, and landscape simulation models for conservation planning

    Science.gov (United States)

    Michael A. Larson; Frank R., III Thompson; Joshua J. Millspaugh; William D. Dijak; Stephen R. Shifley

    2004-01-01

    Methods for habitat modeling based on landscape simulations and population viability modeling based on habitat quality are well developed, but no published study of which we are aware has effectively joined them in a single, comprehensive analysis. We demonstrate the application of a population viability model for ovenbirds (Seiurus aurocapillus)...

  19. A Gompertz population model with Allee effect and fuzzy initial values

    Science.gov (United States)

    Amarti, Zenia; Nurkholipah, Nenden Siti; Anggriani, Nursanti; Supriatna, Asep K.

    2018-03-01

    Growth and population dynamics models are important tools used in preparing a good management for society to predict the future of population or species. This has been done by various known methods, one among them is by developing a mathematical model that describes population growth. Models are usually formed into differential equations or systems of differential equations, depending on the complexity of the underlying properties of the population. One example of biological complexity is Allee effect. It is a phenomenon showing a high correlation between very small population size and the mean individual fitness of the population. In this paper the population growth model used is the Gompertz equation model by considering the Allee effect on the population. We explore the properties of the solution to the model numerically using the Runge-Kutta method. Further exploration is done via fuzzy theoretical approach to accommodate uncertainty of the initial values of the model. It is known that an initial value greater than the Allee threshold will cause the solution rises towards carrying capacity asymptotically. However, an initial value smaller than the Allee threshold will cause the solution decreases towards zero asymptotically, which means the population is eventually extinct. Numerical solutions show that modeling uncertain initial value of the critical point A (the Allee threshold) with a crisp initial value could cause the extinction of population of a certain possibilistic degree, depending on the predetermined membership function of the initial value.

  20. Understanding differences in access and use of healthcare between international immigrants to Chile and the Chilean-born: a repeated cross-sectional population-based study in Chile.

    Science.gov (United States)

    Cabieses, Baltica; Tunstall, Helena; Pickett, Kate E; Gideon, Jasmine

    2012-11-16

    International evidence indicates consistently lower rates of access and use of healthcare by international immigrants. Factors associated with this phenomenon vary significantly depending on the context. Some research into the health of immigrants has been conducted in Latin America, mostly from a qualitative perspective. This population-based study is the first quantitative study to explore healthcare provision entitlement and use of healthcare services by immigrants in Chile and compare them to the Chilean-born. Data come from the nationally representative CASEN (Socioeconomic characterization of the population in Chile) surveys, conducted in 2006 and 2009. Self-reported immigrants were compared to the Chilean-born, by demographic characteristics (age, sex, urban/rural, household composition, ethnicity), socioeconomic status (SES: education, household income, contractual status), healthcare provision entitlement (public, private, other, none), and use of primary services. Weighted descriptive, stratified and adjusted regression models were used to analyse factors associated with access to and use of healthcare. There was an increase in self-reported immigrant status and in household income inequality among immigrants between 2006 and 2009. Over time there was a decrease in the rate of immigrants reporting no healthcare provision and an increase in reporting of private healthcare provision entitlement. Compared to the Chilean-born, immigrants reported higher rates of use of antenatal and gynaecological care, lower use of well-baby care, and no difference in the use of Pap smears or the number of attentions received in the last three months. Immigrants in the bottom income quintile were four times more likely to report no healthcare provision than their equivalent Chilean-born group (with different health needs, i.e. vertical inequity). Disabled immigrants were more likely to have no healthcare provision compared to the disabled Chilean-born (with similar health

  1. Discrete two-sex models of population dynamics: On modelling the mating function

    Science.gov (United States)

    Bessa-Gomes, Carmen; Legendre, Stéphane; Clobert, Jean

    2010-09-01

    Although sexual reproduction has long been a central subject of theoretical ecology, until recently its consequences for population dynamics were largely overlooked. This is now changing, and many studies have addressed this issue, showing that when the mating system is taken into account, the population dynamics depends on the relative abundance of males and females, and is non-linear. Moreover, sexual reproduction increases the extinction risk, namely due to the Allee effect. Nevertheless, different studies have identified diverse potential consequences, depending on the choice of mating function. In this study, we investigate the consequences of three alternative mating functions that are frequently used in discrete population models: the minimum; the harmonic mean; and the modified harmonic mean. We consider their consequences at three levels: on the probability that females will breed; on the presence and intensity of the Allee effect; and on the extinction risk. When we consider the harmonic mean, the number of times the individuals of the least abundant sex mate exceeds their mating potential, which implies that with variable sex-ratios the potential reproductive rate is no longer under the modeller's control. Consequently, the female breeding probability exceeds 1 whenever the sex-ratio is male-biased, which constitutes an obvious problem. The use of the harmonic mean is thus only justified if we think that this parameter should be re-defined in order to represent the females' breeding rate and the fact that females may reproduce more than once per breeding season. This phenomenon buffers the Allee effect, and reduces the extinction risk. However, when we consider birth-pulse populations, such a phenomenon is implausible because the number of times females can reproduce per birth season is limited. In general, the minimum or modified harmonic mean mating functions seem to be more suitable for assessing the impact of mating systems on population dynamics.

  2. Data Driven Approach for High Resolution Population Distribution and Dynamics Models

    Energy Technology Data Exchange (ETDEWEB)

    Bhaduri, Budhendra L [ORNL; Bright, Eddie A [ORNL; Rose, Amy N [ORNL; Liu, Cheng [ORNL; Urban, Marie L [ORNL; Stewart, Robert N [ORNL

    2014-01-01

    High resolution population distribution data are vital for successfully addressing critical issues ranging from energy and socio-environmental research to public health to human security. Commonly available population data from Census is constrained both in space and time and does not capture population dynamics as functions of space and time. This imposes a significant limitation on the fidelity of event-based simulation models with sensitive space-time resolution. This paper describes ongoing development of high-resolution population distribution and dynamics models, at Oak Ridge National Laborato