The stochastic resonance for the incidence function model of metapopulation
Li, Jiang-Cheng; Dong, Zhi-Wei; Zhou, Ruo-Wei; Li, Yun-Xian; Qian, Zhen-Wei
2017-06-01
A stochastic model with endogenous and exogenous periodicities is proposed in this paper on the basis of metapopulation dynamics to model the crop yield losses due to pests and diseases. The rationale is that crop yield losses occur because the physiology of the growing crop is negatively affected by pests and diseases in a dynamic way over time as crop both grows and develops. Metapopulation dynamics can thus be used to model the resultant crop yield losses. The stochastic metapopulation process is described by using the Simplified Incidence Function model (IFM). Compared to the original IFMs, endogenous and exogenous periodicities are considered in the proposed model to handle the cyclical patterns observed in pest infestations, diseases epidemics, and exogenous affecting factors such as temperature and rainfalls. Agricultural loss data in China are used to fit the proposed model. Experimental results demonstrate that: (1) Model with endogenous and exogenous periodicities is a better fit; (2) When the internal system fluctuations and external environmental fluctuations are negatively correlated, EIL or the cost of loss is monotonically increasing; when the internal system fluctuations and external environmental fluctuations are positively correlated, an outbreak of pests and diseases might occur; (3) If the internal system fluctuations and external environmental fluctuations are positively correlated, an optimal patch size can be identified which will greatly weaken the effects of external environmental influence and hence inhibit pest infestations and disease epidemics.
Flexible parametric modelling of cause-specific hazards to estimate cumulative incidence functions
2013-01-01
Background Competing risks are a common occurrence in survival analysis. They arise when a patient is at risk of more than one mutually exclusive event, such as death from different causes, and the occurrence of one of these may prevent any other event from ever happening. Methods There are two main approaches to modelling competing risks: the first is to model the cause-specific hazards and transform these to the cumulative incidence function; the second is to model directly on a transformation of the cumulative incidence function. We focus on the first approach in this paper. This paper advocates the use of the flexible parametric survival model in this competing risk framework. Results An illustrative example on the survival of breast cancer patients has shown that the flexible parametric proportional hazards model has almost perfect agreement with the Cox proportional hazards model. However, the large epidemiological data set used here shows clear evidence of non-proportional hazards. The flexible parametric model is able to adequately account for these through the incorporation of time-dependent effects. Conclusion A key advantage of using this approach is that smooth estimates of both the cause-specific hazard rates and the cumulative incidence functions can be obtained. It is also relatively easy to incorporate time-dependent effects which are commonly seen in epidemiological studies. PMID:23384310
Flexible parametric modelling of the cause-specific cumulative incidence function.
Lambert, Paul C; Wilkes, Sally R; Crowther, Michael J
2017-04-30
Competing risks arise with time-to-event data when individuals are at risk of more than one type of event and the occurrence of one event precludes the occurrence of all other events. A useful measure with competing risks is the cause-specific cumulative incidence function (CIF), which gives the probability of experiencing a particular event as a function of follow-up time, accounting for the fact that some individuals may have a competing event. When modelling the cause-specific CIF, the most common model is a semi-parametric proportional subhazards model. In this paper, we propose the use of flexible parametric survival models to directly model the cause-specific CIF where the effect of follow-up time is modelled using restricted cubic splines. The models provide smooth estimates of the cause-specific CIF with the important advantage that the approach is easily extended to model time-dependent effects. The models can be fitted using standard survival analysis tools by a combination of data expansion and introducing time-dependent weights. Various link functions are available that allow modelling on different scales and have proportional subhazards, proportional odds and relative absolute risks as particular cases. We conduct a simulation study to evaluate how well the spline functions approximate subhazard functions with complex shapes. The methods are illustrated using data from the European Blood and Marrow Transplantation Registry showing excellent agreement between parametric estimates of the cause-specific CIF and those obtained from a semi-parametric model. We also fit models relaxing the proportional subhazards assumption using alternative link functions and/or including time-dependent effects. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
Directory of Open Access Journals (Sweden)
Vanhoy J.R.
2017-01-01
Full Text Available Neutron inelastic scattering cross sections measured directly through (n,n or deduced from γ-ray production cross sections following inelastic neutron scattering (n,n′γ are a focus of basic and applied research at the University of Kentucky Accelerator Laboratory (www.pa.uky.edu/accelerator. For nuclear data applications, angle-integrated cross sections are desired over a wide range of fast neutron energies. Several days of experimental beam time are required for a data set at each incident neutron energy, which limits the number of angular distributions that can be measured in a reasonable amount of time. Approximations can be employed to generate cross sections with a higher energy resolution, since at 125o, the a2P2 term of the Legendre expansion is identically zero and the a4P4 is assumed to be very small. Provided this assumption is true, a single measurement at 125o would produce the γ-ray production cross section. This project tests these assumptions and energy dependences using the codes CINDY/SCAT and TALYS/ECIS06/SCAT. It is found that care must be taken when interpreting γ-ray excitation functions as cross sections when the incident neutron energy is < 1000 keV above threshold or before the onset of feeding.
Vanhoy, J. R.; Ramirez, A. P.; Alcorn-Dominguez, D. K.; Hicks, S. F.; Peters, E. E.; McEllistrem, M. T.; Mukhopadhyay, S.; Yates, S. W.
2017-09-01
Neutron inelastic scattering cross sections measured directly through (n,n) or deduced from γ-ray production cross sections following inelastic neutron scattering (n,n'γ) are a focus of basic and applied research at the University of Kentucky Accelerator Laboratory (www.pa.uky.edu/accelerator). For nuclear data applications, angle-integrated cross sections are desired over a wide range of fast neutron energies. Several days of experimental beam time are required for a data set at each incident neutron energy, which limits the number of angular distributions that can be measured in a reasonable amount of time. Approximations can be employed to generate cross sections with a higher energy resolution, since at 125o, the a2P2 term of the Legendre expansion is identically zero and the a4P4 is assumed to be very small. Provided this assumption is true, a single measurement at 125o would produce the γ-ray production cross section. This project tests these assumptions and energy dependences using the codes CINDY/SCAT and TALYS/ECIS06/SCAT. It is found that care must be taken when interpreting γ-ray excitation functions as cross sections when the incident neutron energy is < 1000 keV above threshold or before the onset of feeding.
Widowhood Fantasies: Incidence, Characteristics, and Potential Function.
Bear, Roberta Meyer; Flowers, Barbara P.
Although some people fantasize about their spouse's possible death, the literature contains no reports of research on widowhood fantasies. The incidence, characteristics, and possible function of these fantasies were examined in individual interviews with 28 divorced and married men and women. Interview data were analyzed by calculating chi-square…
Allard, Robert; Plante, Céline; Garnier, Céline; Kosatsky, Tom
2011-05-01
Previous studies have detected an effect of earlier temperatures on the incidence of campylobacteriosis in humans, but without adjustment for earlier numbers of cases of the disease. We estimated the effect of temperature on the number of cases notified by week in Montreal, Canada, from 1 January 1990 to 26 March 2006, simultaneously with the effect of the numbers of cases notified in the preceding weeks. The current campylobacteriosis count (week 0) was modelled by negative binomial regression, with earlier weekly average temperatures and earlier counts as predictors. Secular trends were accounted for by cubic spline functions and seasonal variations by sine-cosine functions. Indicator variables identified weeks with fewer than 5 working days. In the final statistical model, a 1°C increase in temperature above 10°C during any of weeks -1 to -6 was associated with a 0.8% (95% CI: 0.3% to 1.3%) increase in the current count. For each additional notified case during any of weeks -1 to -5 or -9 to -12, the increase in the current count was approximately 0.5% (95% CI: 0.2% to 1.0%). Thus, earlier temperatures and earlier counts have independent effects, that of temperatures being the larger one. The temperature effect is too small to require short term public health planning. However, in Montreal, an increase in average temperature of the order of 4.5°C, forecast by some for 2055, could produce a 23% increase in incidence, resulting in about 4,000 excess cases per year.
A generative model for predicting terrorist incidents
Verma, Dinesh C.; Verma, Archit; Felmlee, Diane; Pearson, Gavin; Whitaker, Roger
2017-05-01
A major concern in coalition peace-support operations is the incidence of terrorist activity. In this paper, we propose a generative model for the occurrence of the terrorist incidents, and illustrate that an increase in diversity, as measured by the number of different social groups to which that an individual belongs, is inversely correlated with the likelihood of a terrorist incident in the society. A generative model is one that can predict the likelihood of events in new contexts, as opposed to statistical models which are used to predict the future incidents based on the history of the incidents in an existing context. Generative models can be useful in planning for persistent Information Surveillance and Reconnaissance (ISR) since they allow an estimation of regions in the theater of operation where terrorist incidents may arise, and thus can be used to better allocate the assignment and deployment of ISR assets. In this paper, we present a taxonomy of terrorist incidents, identify factors related to occurrence of terrorist incidents, and provide a mathematical analysis calculating the likelihood of occurrence of terrorist incidents in three common real-life scenarios arising in peace-keeping operations
Dynamic prediction of cumulative incidence functions by direct binomial regression.
Grand, Mia K; de Witte, Theo J M; Putter, Hein
2018-03-25
In recent years there have been a series of advances in the field of dynamic prediction. Among those is the development of methods for dynamic prediction of the cumulative incidence function in a competing risk setting. These models enable the predictions to be updated as time progresses and more information becomes available, for example when a patient comes back for a follow-up visit after completing a year of treatment, the risk of death, and adverse events may have changed since treatment initiation. One approach to model the cumulative incidence function in competing risks is by direct binomial regression, where right censoring of the event times is handled by inverse probability of censoring weights. We extend the approach by combining it with landmarking to enable dynamic prediction of the cumulative incidence function. The proposed models are very flexible, as they allow the covariates to have complex time-varying effects, and we illustrate how to investigate possible time-varying structures using Wald tests. The models are fitted using generalized estimating equations. The method is applied to bone marrow transplant data and the performance is investigated in a simulation study. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Modelling and Simulation for Major Incidents
Directory of Open Access Journals (Sweden)
Eleonora Pacciani
2015-11-01
Full Text Available In recent years, there has been a rise in Major Incidents with big impact on the citizens health and the society. Without the possibility of conducting live experiments when it comes to physical and/or toxic trauma, only an accurate in silico reconstruction allows us to identify organizational solutions with the best possible chance of success, in correlation with the limitations on available resources (e.g. medical team, first responders, treatments, transports, and hospitals availability and with the variability of the characteristic of event (e.g. type of incident, severity of the event and type of lesions. Utilizing modelling and simulation techniques, a simplified mathematical model of physiological evolution for patients involved in physical and toxic trauma incident scenarios has been developed and implemented. The model formalizes the dynamics, operating standards and practices of medical response and the main emergency service in the chain of emergency management during a Major Incident.
Incident Duration Modeling Using Flexible Parametric Hazard-Based Models
Directory of Open Access Journals (Sweden)
Ruimin Li
2014-01-01
Full Text Available Assessing and prioritizing the duration time and effects of traffic incidents on major roads present significant challenges for road network managers. This study examines the effect of numerous factors associated with various types of incidents on their duration and proposes an incident duration prediction model. Several parametric accelerated failure time hazard-based models were examined, including Weibull, log-logistic, log-normal, and generalized gamma, as well as all models with gamma heterogeneity and flexible parametric hazard-based models with freedom ranging from one to ten, by analyzing a traffic incident dataset obtained from the Incident Reporting and Dispatching System in Beijing in 2008. Results show that different factors significantly affect different incident time phases, whose best distributions were diverse. Given the best hazard-based models of each incident time phase, the prediction result can be reasonable for most incidents. The results of this study can aid traffic incident management agencies not only in implementing strategies that would reduce incident duration, and thus reduce congestion, secondary incidents, and the associated human and economic losses, but also in effectively predicting incident duration time.
Predicting Cumulative Incidence Probability: Marginal and Cause-Specific Modelling
DEFF Research Database (Denmark)
Scheike, Thomas H.; Zhang, Mei-Jie
2005-01-01
cumulative incidence probability; cause-specific hazards; subdistribution hazard; binomial modelling......cumulative incidence probability; cause-specific hazards; subdistribution hazard; binomial modelling...
Mori, Kentaro; Kaiho, Yu; Tomata, Yasutake; Narita, Mamoru; Tanji, Fumiya; Sugiyama, Kemmyo; Sugawara, Yumi; Tsuji, Ichiro
2017-04-01
To test the hypothesis that elderly persons who feel ikigai (a sense of life worth living) have a lower risk of incident functional disability than those who do not. Recent studies have suggested that ikigai impacts on mortality. However, its impact upon disability is unknown. The aim of the present study was to investigate the association between ikigai and incident functional disability among elderly persons. We conducted a prospective cohort study of 830 Japanese elderly persons aged ≥70 years as a comprehensive geriatric assessment in 2003. Information on ikigai was collected by self-reported questionnaire. Data on functional disability were retrieved from the public Long-term Care Insurance database in which participants were followed up for 11 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incidence of functional disability were calculated for three groups delineated according to the presence of ikigai (“no”, “uncertain” or “yes”) using the Cox proportional hazards regression model. The 11-year incidence of functional disability was 53.3% (442 cases). As compared with the “no” group, the multiple-adjusted HR (95% CI) of incident functional disability was 0.61 (0.36–1.02) for the “uncertain” group and 0.50 (0.30–0.84) for the “yes” group. A stronger degree of ikigai is significantly associated with a lower risk of incident functional disability. Copyright © 2017 Elsevier Inc. All rights reserved.
Sensory and Motor Peripheral Nerve Function and Incident Mobility Disability
DEFF Research Database (Denmark)
Ward, R. E.; Boudreau, R. M.; Caserotti, P.
2014-01-01
ObjectivesTo assess the relationship between sensorimotor nerve function and incident mobility disability over 10years. DesignProspective cohort study with longitudinal analysis. SettingTwo U.S. clinical sites. ParticipantsPopulation-based sample of community-dwelling older adults with no mobilit...... disability at 2000/01 examination (N=1,680; mean age SD 76.52.9, body mass index 27.14.6; 50.2% female, 36.6% black, 10.7% with diabetes mellitus). MeasurementsMotor nerve conduction amplitude (poor...
Filaggrin loss-of-function mutations and incident cancer
DEFF Research Database (Denmark)
Skaaby, T; Husemoen, L L N; Thyssen, J P
2014-01-01
BACKGROUND: Loss-of-function mutations in the filaggrin gene (FLG) could have opposing effects on cancer risk, as mutations are associated with both 10% higher serum vitamin D levels, which may protect against cancer, and with impaired skin barrier function, which may lead to higher cancer...... susceptibility. OBJECTIVES: To investigate the association of the FLG genotype and cancer types in four population-based cohorts. METHODS: A total of 13,376 individuals were genotyped for FLG mutations. Information on cancer was obtained from the Danish Cancer Registry. Persons with a history of cancer...... at baseline were excluded from prospective analyses. RESULTS: There were 1339 incident cancers (median follow-up 11·4 years). The hazard ratios (HRs) and 95% confidence intervals (CIs) for FLG mutation carriers vs. wild types were: for any cancer (HR 0·95, 95% CI 0·78-1·16), any cancer excluding nonmelanoma...
Incidence and functional evolution of traumatic injuries of the spine
Directory of Open Access Journals (Sweden)
Francisco Alberto Trinidad Ovalle
2014-09-01
Full Text Available OBJECTIVE: To determine the incidence and functional outcome of traumatic injuries of the spine in the period from January 1, 2013 to December 31, 2013, at the General Hospital "Dr. Rafael Pascacio Gamboa", state of Chiapas, México. METHODS: A retrospective, cross-sectional, descriptive, observational study, where all patients seeking medical and surgical care in the emergency department and inpatient unit for a traumatic spinal injury were included, regardless of age or sex. RESULTS: A sample of 60 patients, of whom 43 were male (71.7% and 17 females (28.3%, with an average age of 35 was obtained. As for the cause of the injury, falls were the leading cause (61.7% followed by motor vehicle accidents (35% and finally, assaults (3.3%. In this sample, 21% had associated injuries being the most common (7.3% the thoracic trauma. The most common site of injury was the thoracic spine, followed by the lower cervical and finally the thoracolumbar ones. We found that 70% of patients had partial or complete neurological injury, with complete spinal cord transection (Frankel A being the most frequent lesion in 53%. CONCLUSION: The incidence in our series is similar that the reported in developing countries which have sociocultural problems similar to ours. The same applies to the etiology of these lesions, which is closely linked to social and economic activity in each country or region.
A new, accurate predictive model for incident hypertension
DEFF Research Database (Denmark)
Völzke, Henry; Fung, Glenn; Ittermann, Till
2013-01-01
Data mining represents an alternative approach to identify new predictors of multifactorial diseases. This work aimed at building an accurate predictive model for incident hypertension using data mining procedures....
The proportional odds cumulative incidence model for competing risks
DEFF Research Database (Denmark)
Eriksson, Frank; Li, Jianing; Scheike, Thomas
2015-01-01
We suggest an estimator for the proportional odds cumulative incidence model for competing risks data. The key advantage of this model is that the regression parameters have the simple and useful odds ratio interpretation. The model has been considered by many authors, but it is rarely used in pr...
Nonparametric Transfer Function Models
Liu, Jun M.; Chen, Rong; Yao, Qiwei
2009-01-01
In this paper a class of nonparametric transfer function models is proposed to model nonlinear relationships between ‘input’ and ‘output’ time series. The transfer function is smooth with unknown functional forms, and the noise is assumed to be a stationary autoregressive-moving average (ARMA) process. The nonparametric transfer function is estimated jointly with the ARMA parameters. By modeling the correlation in the noise, the transfer function can be estimated more efficiently. The parsimonious ARMA structure improves the estimation efficiency in finite samples. The asymptotic properties of the estimators are investigated. The finite-sample properties are illustrated through simulations and one empirical example. PMID:20628584
Krefis, Anne Caroline; Schwarz, Norbert Georg; Krüger, Andreas; Fobil, Julius; Nkrumah, Bernard; Acquah, Samuel; Loag, Wibke; Sarpong, Nimako; Adu-Sarkodie, Yaw; Ranft, Ulrich; May, Jürgen
2011-02-01
Climatic factors influence the incidence of vector-borne diseases such as malaria. They modify the abundance of mosquito populations, the length of the extrinsic parasite cycle in the mosquito, the malarial dynamics, and the emergence of epidemics in areas of low endemicity. The objective of this study was to investigate temporal associations between weekly malaria incidence in 1,993 children < 15 years of age and weekly rainfall. A time series analysis was conducted by using cross-correlation function and autoregressive modeling. The regression model showed that the level of rainfall predicted the malaria incidence after a time lag of 9 weeks (mean = 60 days) and after a time lag between one and two weeks. The analyses provide evidence that high-resolution precipitation data can directly predict malaria incidence in a highly endemic area. Such models might enable the development of early warning systems and support intervention measures.
Addressing water incidents by using pipe network models
CSIR Research Space (South Africa)
Yoyo, Sonwabiso
2016-05-01
Full Text Available NETWORK MODELS Sonwabiso YOYO, Philip R. PAGE, S’Bonelo ZULU, Frances A’BEAR 1 1 Built Environment, Council for Scientific and Industrial Research (CSIR), 11 Jan Cilliers Road, Stellenbosch, South Africa, 7600. Tel: +27 (21) 888 2478. Email: syoyo...) in Business Day Live, nearly 40% of municipal water is lost before reaching the consumer. PURPOSE OF THE STUDY The study seeks to address water incidents by using pipe network models and associated components. This is specifically in observation...
Ferree, Steven; van der Vliet, Quirine M J; van Heijl, Mark; Houwert, Roderick M; Leenen, Luke P H; Hietbrink, Falco
INTRODUCTION: Injuries of the hand can cause significant functional impairment, diminished quality of life and delayed return to work. However, the incidence and functional outcome of hand injuries in polytrauma patients is currently unknown. The aim of this study was to determine the incidence,
Accident Analysis and Barrier Function (AEB) Method. Manual for Incident Analysis
International Nuclear Information System (INIS)
Svenson, Ola
2000-02-01
The Accident Analysis and Barrier Function (AEB) Method models an accident or incident as a series of interactions between human and technical systems. In the sequence of human and technical errors leading to an accident there is, in principle, a possibility to arrest the development between each two successive errors. This can be done by a barrier function which, for example, can stop an operator from making an error. A barrier function can be performed by one or several barrier function systems. To illustrate, a mechanical system, a computer system or another operator can all perform a given barrier function to stop an operator from making an error. The barrier function analysis consists of analysis of suggested improvements, the effectiveness of the improvements, the costs of implementation, probability of implementation, the cost of maintaining the barrier function, the probability that maintenance will be kept up to standards and the generalizability of the suggested improvement. The AEB method is similar to the US method called HPES, but differs from that method in different ways. To exemplify, the AEB method has more emphasis on technical errors than HPES. In contrast to HPES that describes a series of events, the AEB method models only errors. This gives a more focused analysis making it well suited for checking other HPES-type accident analyses. However, the AEB method is a generic and stand-alone method that has been applied in other fields than nuclear power, such as, in traffic accident analyses
Executive function, but not memory, associates with incident coronary heart disease and stroke.
Rostamian, Somayeh; van Buchem, Mark A; Westendorp, Rudi G J; Jukema, J Wouter; Mooijaart, Simon P; Sabayan, Behnam; de Craen, Anton J M
2015-09-01
To evaluate the association of performance in cognitive domains executive function and memory with incident coronary heart disease and stroke in older participants without dementia. We included 3,926 participants (mean age 75 years, 44% male) at risk for cardiovascular diseases from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER) with Mini-Mental State Examination score ≥24 points. Scores on the Stroop Color-Word Test (selective attention) and the Letter Digit Substitution Test (processing speed) were converted to Z scores and averaged into a composite executive function score. Likewise, scores of the Picture Learning Test (immediate and delayed memory) were transformed into a composite memory score. Associations of executive function and memory were longitudinally assessed with risk of coronary heart disease and stroke using multivariable Cox regression models. During 3.2 years of follow-up, incidence rates of coronary heart disease and stroke were 30.5 and 12.4 per 1,000 person-years, respectively. In multivariable models, participants in the lowest third of executive function, as compared to participants in the highest third, had 1.85-fold (95% confidence interval [CI] 1.39-2.45) higher risk of coronary heart disease and 1.51-fold (95% CI 0.99-2.30) higher risk of stroke. Participants in the lowest third of memory had no increased risk of coronary heart disease (hazard ratio 0.99, 95% CI 0.74-1.32) or stroke (hazard ratio 0.87, 95% CI 0.57-1.32). Lower executive function, but not memory, is associated with higher risk of coronary heart disease and stroke. Lower executive function, as an independent risk indicator, might better reflect brain vascular pathologies. © 2015 American Academy of Neurology.
Prediction Model for Gastric Cancer Incidence in Korean Population.
Eom, Bang Wool; Joo, Jungnam; Kim, Sohee; Shin, Aesun; Yang, Hye-Ryung; Park, Junghyun; Choi, Il Ju; Kim, Young-Woo; Kim, Jeongseon; Nam, Byung-Ho
2015-01-01
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.
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.
A new, accurate predictive model for incident hypertension.
Völzke, Henry; Fung, Glenn; Ittermann, Till; Yu, Shipeng; Baumeister, Sebastian E; Dörr, Marcus; Lieb, Wolfgang; Völker, Uwe; Linneberg, Allan; Jørgensen, Torben; Felix, Stephan B; Rettig, Rainer; Rao, Bharat; Kroemer, Heyo K
2013-11-01
Data mining represents an alternative approach to identify new predictors of multifactorial diseases. This work aimed at building an accurate predictive model for incident hypertension using data mining procedures. The primary study population consisted of 1605 normotensive individuals aged 20-79 years with 5-year follow-up from the population-based study, that is the Study of Health in Pomerania (SHIP). The initial set was randomly split into a training and a testing set. We used a probabilistic graphical model applying a Bayesian network to create a predictive model for incident hypertension and compared the predictive performance with the established Framingham risk score for hypertension. Finally, the model was validated in 2887 participants from INTER99, a Danish community-based intervention study. In the training set of SHIP data, the Bayesian network used a small subset of relevant baseline features including age, mean arterial pressure, rs16998073, serum glucose and urinary albumin concentrations. Furthermore, we detected relevant interactions between age and serum glucose as well as between rs16998073 and urinary albumin concentrations [area under the receiver operating characteristic (AUC 0.76)]. The model was confirmed in the SHIP validation set (AUC 0.78) and externally replicated in INTER99 (AUC 0.77). Compared to the established Framingham risk score for hypertension, the predictive performance of the new model was similar in the SHIP validation set and moderately better in INTER99. Data mining procedures identified a predictive model for incident hypertension, which included innovative and easy-to-measure variables. The findings promise great applicability in screening settings and clinical practice.
Modeling a SI epidemic with stochastic transmission: hyperbolic incidence rate.
Christen, Alejandra; Maulén-Yañez, M Angélica; González-Olivares, Eduardo; Curé, Michel
2018-03-01
In this paper a stochastic susceptible-infectious (SI) epidemic model is analysed, which is based on the model proposed by Roberts and Saha (Appl Math Lett 12: 37-41, 1999), considering a hyperbolic type nonlinear incidence rate. Assuming the proportion of infected population varies with time, our new model is described by an ordinary differential equation, which is analogous to the equation that describes the double Allee effect. The limit of the solution of this equation (deterministic model) is found when time tends to infinity. Then, the asymptotic behaviour of a stochastic fluctuation due to the environmental variation in the coefficient of disease transmission is studied. Thus a stochastic differential equation (SDE) is obtained and the existence of a unique solution is proved. Moreover, the SDE is analysed through the associated Fokker-Planck equation to obtain the invariant measure when the proportion of the infected population reaches steady state. An explicit expression for invariant measure is found and we study some of its properties. The long time behaviour of deterministic and stochastic models are compared by simulations. According to our knowledge this incidence rate has not been previously used for this type of epidemic models.
Bayesian geostatistical modeling of leishmaniasis incidence in Brazil.
Directory of Open Access Journals (Sweden)
Dimitrios-Alexios Karagiannis-Voules
Full Text Available BACKGROUND: Leishmaniasis is endemic in 98 countries with an estimated 350 million people at risk and approximately 2 million cases annually. Brazil is one of the most severely affected countries. METHODOLOGY: We applied Bayesian geostatistical negative binomial models to analyze reported incidence data of cutaneous and visceral leishmaniasis in Brazil covering a 10-year period (2001-2010. Particular emphasis was placed on spatial and temporal patterns. The models were fitted using integrated nested Laplace approximations to perform fast approximate Bayesian inference. Bayesian variable selection was employed to determine the most important climatic, environmental, and socioeconomic predictors of cutaneous and visceral leishmaniasis. PRINCIPAL FINDINGS: For both types of leishmaniasis, precipitation and socioeconomic proxies were identified as important risk factors. The predicted number of cases in 2010 were 30,189 (standard deviation [SD]: 7,676 for cutaneous leishmaniasis and 4,889 (SD: 288 for visceral leishmaniasis. Our risk maps predicted the highest numbers of infected people in the states of Minas Gerais and Pará for visceral and cutaneous leishmaniasis, respectively. CONCLUSIONS/SIGNIFICANCE: Our spatially explicit, high-resolution incidence maps identified priority areas where leishmaniasis control efforts should be targeted with the ultimate goal to reduce disease incidence.
Forecasting tuberculosis incidence in iran using box-jenkins models.
Moosazadeh, Mahmood; Nasehi, Mahshid; Bahrampour, Abbas; Khanjani, Narges; Sharafi, Saeed; Ahmadi, Shanaz
2014-05-01
Predicting the incidence of tuberculosis (TB) plays an important role in planning health control strategies for the future, developing intervention programs and allocating resources. The present longitudinal study estimated the incidence of tuberculosis in 2014 using Box-Jenkins methods. Monthly data of tuberculosis cases recorded in the surveillance system of Iran tuberculosis control program from 2005 till 2011 was used. Data was reviewed regarding normality, variance equality and stationary conditions. The parameters p, d and q and P, D and Q were determined, and different models were examined. Based on the lowest levels of AIC and BIC, the most suitable model was selected among the models whose overall adequacy was confirmed. During 84 months, 63568 TB patients were recorded. The average was 756.8 (SD = 11.9) TB cases a month. SARIMA (0,1,1)(0,1,1)12 with the lowest level of AIC (12.78) was selected as the most adequate model for prediction. It was predicted that the total nationwide TB cases for 2014 will be about 16.75 per 100,000 people. Regarding the cyclic pattern of TB recorded cases, Box-Jenkins and SARIMA models are suitable for predicting its prevalence in future. Moreover, prediction results show an increasing trend of TB cases in Iran.
Modeling for comparison of leukemia incidence risk between nuclear and coal power industries
International Nuclear Information System (INIS)
Prybutok, V.R.; Gold, L.M.
1987-01-01
The leukemia incidence risk for a single coal plant, a single nuclear plant, and a single nuclear accident is used to compute the total industry leukemia incidence risk. In the absence of a nuclear power plant accident, the leukemia incidence risk is normally lower for a nuclear industry than for a coal industry of equivalent size. The nuclear industry risk with accidents was compared to the coal industry risk for six proposed dose response curves. Simplifying assumptions about the negligible effect of the cell-killing term and the linear nature of the linear quadratic curve allowed derivation of risk models for the assumption of both linear and quadratic dose response. These derived models, representing leukemia incidence risk bounds, are used to estimate the total industry risk comparison. Evaluation of an accident's impact on the leukemia incidence risk comparison is done with the risk bounds and compared to the risk evaluations calculated during all six dose response curves. The overlapping plot of the number of nuclear accidents required for equivalent industry environment risks versus the accident fraction allows the conservative function to be defined
Yanik, Elizabeth L; Clarke, Christina A; Snyder, Jon J; Pfeiffer, Ruth M; Engels, Eric A
2016-05-01
Among patients with ESRD, cancer risk is affected by kidney dysfunction and by immunosuppression after transplant. Assessing patterns across periods of dialysis and kidney transplantation may inform cancer etiology. We evaluated 202,195 kidney transplant candidates and recipients from a linkage between the Scientific Registry of Transplant Recipients and cancer registries, and compared incidence in kidney function intervals (time with a transplant) with incidence in nonfunction intervals (waitlist or time after transplant failure), adjusting for demographic factors. Incidence of infection-related and immune-related cancer was higher during kidney function intervals than during nonfunction intervals. Incidence was most elevated for Kaposi sarcoma (hazard ratio [HR], 9.1; 95% confidence interval (95% CI), 4.7 to 18), non-Hodgkin's lymphoma (HR, 3.2; 95% CI, 2.8 to 3.7), Hodgkin's lymphoma (HR, 3.0; 95% CI, 1.7 to 5.3), lip cancer (HR, 3.4; 95% CI, 2.0 to 6.0), and nonepithelial skin cancers (HR, 3.8; 95% CI, 2.5 to 5.8). Conversely, ESRD-related cancer incidence was lower during kidney function intervals (kidney cancer: HR, 0.8; 95% CI, 0.7 to 0.8 and thyroid cancer: HR, 0.7; 95% CI, 0.6 to 0.8). With each successive interval, incidence changed in alternating directions for non-Hodgkin's lymphoma, melanoma, and lung, pancreatic, and nonepithelial skin cancers (higher during function intervals), and kidney and thyroid cancers (higher during nonfunction intervals). For many cancers, incidence remained higher than in the general population across all intervals. These data indicate strong short-term effects of kidney dysfunction and immunosuppression on cancer incidence in patients with ESRD, suggesting a need for persistent cancer screening and prevention. Copyright © 2016 by the American Society of Nephrology.
Smooth semi-nonparametric (SNP) estimation of the cumulative incidence function.
Duc, Anh Nguyen; Wolbers, Marcel
2017-08-15
This paper presents a novel approach to estimation of the cumulative incidence function in the presence of competing risks. The underlying statistical model is specified via a mixture factorization of the joint distribution of the event type and the time to the event. The time to event distributions conditional on the event type are modeled using smooth semi-nonparametric densities. One strength of this approach is that it can handle arbitrary censoring and truncation while relying on mild parametric assumptions. A stepwise forward algorithm for model estimation and adaptive selection of smooth semi-nonparametric polynomial degrees is presented, implemented in the statistical software R, evaluated in a sequence of simulation studies, and applied to data from a clinical trial in cryptococcal meningitis. The simulations demonstrate that the proposed method frequently outperforms both parametric and nonparametric alternatives. They also support the use of 'ad hoc' asymptotic inference to derive confidence intervals. An extension to regression modeling is also presented, and its potential and challenges are discussed. © 2017 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd. © 2017 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.
Liu, Qun; Jiang, Daqing
2017-08-01
In this paper, a stochastic Susceptible-Infected-Susceptible (SIS) epidemic model with double diseases and the Beddington-DeAngelis incidence is proposed and studied. Sufficient conditions for the existence of an ergodic stationary distribution of the positive solutions to the model are obtained via the Lyapunov function method. The existence of stationary distribution implies stochastic stability to some extent.
Liu, Qun; Jiang, Daqing
2017-08-01
In this paper, a stochastic Susceptible-Infected-Susceptible (SIS) epidemic model with double diseases and the Beddington-DeAngelis incidence is proposed and studied. Sufficient conditions for the existence of an ergodic stationary distribution of the positive solutions to the model are obtained via the Lyapunov function method. The existence of stationary distribution implies stochastic stability to some extent.
DEFF Research Database (Denmark)
Effraimidis, Georgios; Dahl, Christian Møller
In this paper, we develop a fully nonparametric approach for the estimation of the cumulative incidence function with Missing At Random right-censored competing risks data. We obtain results on the pointwise asymptotic normality as well as the uniform convergence rate of the proposed nonparametri...
Spatio-temporal modelling of dengue fever incidence in Malaysia
Che-Him, Norziha; Ghazali Kamardan, M.; Saifullah Rusiman, Mohd; Sufahani, Suliadi; Mohamad, Mahathir; @ Kamariah Kamaruddin, Nafisah
2018-04-01
Previous studies reported significant relationship between dengue incidence rate (DIR) and both climatic and non-climatic factors. Therefore, this study proposes a generalised additive model (GAM) framework for dengue risk in Malaysia by using both climatic and non-climatic factors. The data used is monthly DIR for 12 states of Malaysia from 2001 to 2009. In this study, we considered an annual trend, seasonal effects, population, population density and lagged DIR, rainfall, temperature, number of rainy days and El Niño-Southern Oscillation (ENSO). The population density is found to be positively related to monthly DIR. There are generally weak relationships between monthly DIR and climate variables. A negative binomial GAM shows that there are statistically significant relationships between DIR with climatic and non-climatic factors. These include mean rainfall and temperature, the number of rainy days, sea surface temperature and the interaction between mean temperature (lag 1 month) and sea surface temperature (lag 6 months). These also apply to DIR (lag 3 months) and population density.
Global stability of a network-based SIS epidemic model with a general nonlinear incidence rate.
Huang, Shouying; Jiang, Jifa
2016-08-01
In this paper, we develop and analyze an SIS epidemic model with a general nonlinear incidence rate, as well as degree-dependent birth and natural death, on heterogeneous networks. We analytically derive the epidemic threshold R0 which completely governs the disease dynamics: when R0 1, the disease is permanent. It is interesting that the threshold value R0 bears no relation to the functional form of the nonlinear incidence rate and degree-dependent birth. Furthermore, by applying an iteration scheme and the theory of cooperative system respectively, we obtain sufficient conditions under which the endemic equilibrium is globally asymptotically stable. Our results improve and generalize some known results. To illustrate the theoretical results, the corresponding numerical simulations are also given.
Sahle, Berhe W; Owen, Alice J; Chin, Ken Lee; Reid, Christopher M
2017-09-01
Numerous models predicting the risk of incident heart failure (HF) have been developed; however, evidence of their methodological rigor and reporting remains unclear. This study critically appraises the methods underpinning incident HF risk prediction models. EMBASE and PubMed were searched for articles published between 1990 and June 2016 that reported at least 1 multivariable model for prediction of HF. Model development information, including study design, variable coding, missing data, and predictor selection, was extracted. Nineteen studies reporting 40 risk prediction models were included. Existing models have acceptable discriminative ability (C-statistics > 0.70), although only 6 models were externally validated. Candidate variable selection was based on statistical significance from a univariate screening in 11 models, whereas it was unclear in 12 models. Continuous predictors were retained in 16 models, whereas it was unclear how continuous variables were handled in 16 models. Missing values were excluded in 19 of 23 models that reported missing data, and the number of events per variable was models. Only 2 models presented recommended regression equations. There was significant heterogeneity in discriminative ability of models with respect to age (P prediction models that had sufficient discriminative ability, although few are externally validated. Methods not recommended for the conduct and reporting of risk prediction modeling were frequently used, and resulting algorithms should be applied with caution. Copyright © 2017 Elsevier Inc. All rights reserved.
Disease control of delay SEIR model with nonlinear incidence rate and vertical transmission.
Cheng, Yan; Pan, Qiuhui; He, Mingfeng
2013-01-01
The aim of this paper is to develop two delayed SEIR epidemic models with nonlinear incidence rate, continuous treatment, and impulsive vaccination for a class of epidemic with latent period and vertical transition. For continuous treatment, we obtain a basic reproductive number ℜ0 and prove the global stability by using the Lyapunov functional method. We obtain two thresholds ℜ* and ℜ∗ for impulsive vaccination and prove that if ℜ* 1, then the disease is permanent by using the comparison theorem of impulsive differential equation. Numerical simulations indicate that pulse vaccination strategy or a longer latent period will make the population size infected by a disease decrease.
Asymptotic behavior of a stochastic delayed HIV-1 infection model with nonlinear incidence
Liu, Qun; Jiang, Daqing; Hayat, Tasawar; Ahmad, Bashir
2017-11-01
In this paper, a stochastic delayed HIV-1 infection model with nonlinear incidence is proposed and investigated. First of all, we prove that there is a unique global positive solution as desired in any population dynamics. Then by constructing some suitable Lyapunov functions, we show that if the basic reproduction number R0 ≤ 1, then the solution of the stochastic system oscillates around the infection-free equilibrium E0, while if R0 > 1, then the solution of the stochastic system fluctuates around the infective equilibrium E∗. Sufficient conditions of these results are established. Finally, we give some examples and a series of numerical simulations to illustrate the analytical results.
Modelling malaria incidence by an autoregressive distributed lag model with spatial component.
Laguna, Francisco; Grillet, María Eugenia; León, José R; Ludeña, Carenne
2017-08-01
The influence of climatic variables on the dynamics of human malaria has been widely highlighted. Also, it is known that this mosquito-borne infection varies in space and time. However, when the data is spatially incomplete most popular spatio-temporal methods of analysis cannot be applied directly. In this paper, we develop a two step methodology to model the spatio-temporal dependence of malaria incidence on local rainfall, temperature, and humidity as well as the regional sea surface temperatures (SST) in the northern coast of Venezuela. First, we fit an autoregressive distributed lag model (ARDL) to the weekly data, and then, we adjust a linear separable spacial vectorial autoregressive model (VAR) to the residuals of the ARDL. Finally, the model parameters are tuned using a Markov Chain Monte Carlo (MCMC) procedure derived from the Metropolis-Hastings algorithm. Our results show that the best model to account for the variations of malaria incidence from 2001 to 2008 in 10 endemic Municipalities in North-Eastern Venezuela is a logit model that included the accumulated local precipitation in combination with the local maximum temperature of the preceding month as positive regressors. Additionally, we show that although malaria dynamics is highly heterogeneous in space, a detailed analysis of the estimated spatial parameters in our model yield important insights regarding the joint behavior of the disease incidence across the different counties in our study. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Chelsea Uggenti
2018-03-01
Full Text Available We begin with a detailed study of a delayed SI model of disease transmission with immigration into both classes. The incidence function allows for a nonlinear dependence on the infected population, including mass action and saturating incidence as special cases. Due to the immigration of infectives, there is no disease-free equilibrium and hence no basic reproduction number. We show there is a unique endemic equilibrium and that this equilibrium is globally asymptotically stable for all parameter values. The results include vector-style delay and latency-style delay. Next, we show that previous global stability results for an SEI model and an SVI model that include immigration of infectives and non-linear incidence but not delay can be extended to systems with vector-style delay and latency-style delay.
Spatio-seasonal modeling of the incidence rate of malaria in Mozambique
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Nhalungo Delino
2008-10-01
Full Text Available Abstract Background The objective was to study the seasonal effect on the spatial distribution of the incidence of malaria in children under 10 years old living in the Manhiça district, Mozambique. Methods The data of the clinical malaria incidence were obtained from a study of two cohorts of children followed from December 1996 to July 1999. The cases were obtained by the active detection method. Hierarchical Bayesian models were used to model the incidence of malaria, including spatial correlation nested to climatic season. The models were compared with the deviance information criterion. The age and gender of the children were also taken into account. Results The incidence of malaria is associated with age, period and climate season. The incidence presents a clear spatial pattern, with a higher incidence in the neighbourhoods situated in the north and northeast of the Manhiça area. The transmission of malaria is highest during the wet season but the spatial pattern of malaria does not differ from that during the dry season. Conclusion The incidence of malaria in Manhiça presents a spatial pattern which is independent of the seasonal climatic conditions. The climate modifies the incidence of malaria in the entire region but does not change the spatial pattern of the incidence of this disease. These findings may be useful for the planning of malaria control activities. These activities can be performed taking account that the neighbourhoods with more incidence of malaria do not change over the annual climate seasons.
Statistical modelling with quantile functions
Gilchrist, Warren
2000-01-01
Galton used quantiles more than a hundred years ago in describing data. Tukey and Parzen used them in the 60s and 70s in describing populations. Since then, the authors of many papers, both theoretical and practical, have used various aspects of quantiles in their work. Until now, however, no one put all the ideas together to form what turns out to be a general approach to statistics.Statistical Modelling with Quantile Functions does just that. It systematically examines the entire process of statistical modelling, starting with using the quantile function to define continuous distributions. The author shows that by using this approach, it becomes possible to develop complex distributional models from simple components. A modelling kit can be developed that applies to the whole model - deterministic and stochastic components - and this kit operates by adding, multiplying, and transforming distributions rather than data.Statistical Modelling with Quantile Functions adds a new dimension to the practice of stati...
Functional Scaling of Musculoskeletal Models
DEFF Research Database (Denmark)
Lund, Morten Enemark; Andersen, Michael Skipper; de Zee, Mark
specific to the patient. This is accomplished using optimisation methods to determine patient-specific joint positions and orientations, which minimise the least-squares error between model markers and the recorded markers from a motion capture experiment. Functional joint positions and joint axis...... geometry, without the need for MR/CT scans. However, more validation activities are needed to better understand the effect of morphing musculoskeletal models based on functional joint parameters....
Functioning with a Sticky Model.
Reys, Robert E.
1981-01-01
A model that can be effectively used to develop the notion of function and provide varied practice by using "real world" examples and concrete objects is covered. The use of Popsicle-sticks is featured, with some suggestions for tasks involving functions with one operation, two operations, and inverse operations covered. (MP)
An SIRS Epidemic Model with Vital Dynamics and a Ratio-Dependent Saturation Incidence Rate
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Xinli Wang
2015-01-01
Full Text Available This paper presents an investigation on the dynamics of an epidemic model with vital dynamics and a nonlinear incidence rate of saturated mass action as a function of the ratio of the number of the infectives to that of the susceptibles. The stabilities of the disease-free equilibrium and the endemic equilibrium are first studied. Under the assumption of nonexistence of periodic solution, the global dynamics of the model is established: either the number of infective individuals tends to zero as time evolves or it produces bistability in which there is a region such that the disease will persist if the initial position lies in the region and disappears if the initial position lies outside this region. Computer simulation shows such results.
Tanji, Fumiya; Sugawara, Yumi; Tomata, Yasutake; Watanabe, Takashi; Sugiyama, Kemmyo; Kaiho, Yu; Tomita, Hiroaki; Tsuji, Ichiro
2017-10-15
We conducted a prospective cohort study to investigate whether psychological distress would have increased the incident risk of functional disability after the 2011 Great East Japan Earthquake. First phase data pertaining to psychological distress and other lifestyle factors were collected from 1037 subjects aged ≥ 65 years, from June to December 2011, in four affected areas of Miyagi prefecture in Japan. Psychological distress was measured by the Kessler 6-item psychological distress scale (K6), and classified into three categories (K6 score ≤ 9, 10-12, ≥ 13). Outcome data on functional disability were collected from the public Long-term Care Insurance database. Participants were followed up for about 2.6 years. The Cox model was used to calculate the multivariate hazard ratios (HRs) and 95% confidence intervals (CIs). During the follow-up period, 118 participants were certified as incident disability (43.8 disability events per 1000 person-years). Compared with the lowest category (K6 score ≤ 9), participants in the highest category (K6 score ≥ 13) had a significantly higher risk of functional disability (HR = 2.65, 95% CI = 1.35-5.18, p = 0.002). In order to consider reverse causality, we conducted analysis excluding all incidents and deaths that occurred within the first year of follow-up, but our findings remained unchanged. We did not consider all potential confounders and use of appropriate medication. The present study has demonstrated that psychological distress was associated with an increased risk of functional disability among elderly survivors of a natural disaster. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.
A deterministic width function model
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C. E. Puente
2003-01-01
Full Text Available Use of a deterministic fractal-multifractal (FM geometric method to model width functions of natural river networks, as derived distributions of simple multifractal measures via fractal interpolating functions, is reported. It is first demonstrated that the FM procedure may be used to simulate natural width functions, preserving their most relevant features like their overall shape and texture and their observed power-law scaling on their power spectra. It is then shown, via two natural river networks (Racoon and Brushy creeks in the United States, that the FM approach may also be used to closely approximate existing width functions.
Effect of climate variables on cocoa black pod incidence in Sabah using ARIMAX model
Ling Sheng Chang, Albert; Ramba, Haya; Mohd. Jaaffar, Ahmad Kamil; Kim Phin, Chong; Chong Mun, Ho
2016-06-01
Cocoa black pod disease is one of the major diseases affecting the cocoa production in Malaysia and also around the world. Studies have shown that the climate variables have influenced the cocoa black pod disease incidence and it is important to quantify the black pod disease variation due to the effect of climate variables. Application of time series analysis especially auto-regressive moving average (ARIMA) model has been widely used in economics study and can be used to quantify the effect of climate variables on black pod incidence to forecast the right time to control the incidence. However, ARIMA model does not capture some turning points in cocoa black pod incidence. In order to improve forecasting performance, other explanatory variables such as climate variables should be included into ARIMA model as ARIMAX model. Therefore, this paper is to study the effect of climate variables on the cocoa black pod disease incidence using ARIMAX model. The findings of the study showed ARIMAX model using MA(1) and relative humidity at lag 7 days, RHt - 7 gave better R square value compared to ARIMA model using MA(1) which could be used to forecast the black pod incidence to assist the farmers determine timely application of fungicide spraying and culture practices to control the black pod incidence.
Xu, Meng; Xue, Wanli; Ma, Zhenhua; Bai, Jigang
2016-01-01
Purpose. To investigate the preventive effect of resveratrol (RES) on the formation of portal vein system thrombosis (PVST) in a rat fibrosis model. Methods. A total of 64 male SD rats, weighing 200–300 g, were divided into five groups: Sham operation, Splenectomy I, Splenectomy II, RES, and low molecular weight heparin (LMWH), with the former two groups as nonfibrosis controls. Blood samples were subjected to biochemical assays. Platelet apoptosis was measured by flow cytometry. All rats were euthanized for PVST detection one week after operation. Results. No PVST occurred in nonfibrosis controls. Compared to Splenectomy II, the incidences of PVST in RES and LMWH groups were significantly decreased (both p Splenectomy II (all p splenectomy in cirrhotic rat. Regulation of platelet function and induction of platelet apoptosis might be the underlying mechanisms. PMID:27433290
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Meng Xu
2016-01-01
Full Text Available Purpose. To investigate the preventive effect of resveratrol (RES on the formation of portal vein system thrombosis (PVST in a rat fibrosis model. Methods. A total of 64 male SD rats, weighing 200–300 g, were divided into five groups: Sham operation, Splenectomy I, Splenectomy II, RES, and low molecular weight heparin (LMWH, with the former two groups as nonfibrosis controls. Blood samples were subjected to biochemical assays. Platelet apoptosis was measured by flow cytometry. All rats were euthanized for PVST detection one week after operation. Results. No PVST occurred in nonfibrosis controls. Compared to Splenectomy II, the incidences of PVST in RES and LMWH groups were significantly decreased (both p<0.05. Two rats in LMWH group died before euthanasia due to intra-abdominal hemorrhage. In RES group, significant decreases in platelet aggregation, platelet radical oxygen species (ROS production, and increase in platelet nitric oxide (NO synthesis and platelet apoptosis were observed when compared with Splenectomy II (all p<0.001, while in LMWH group only significant decrease in platelet aggregation was observed. Conclusion. Prophylactic application of RES could safely reduce the incidence of PVST after splenectomy in cirrhotic rat. Regulation of platelet function and induction of platelet apoptosis might be the underlying mechanisms.
Zhang functions and various models
Zhang, Yunong
2015-01-01
This book focuses on solving different types of time-varying problems. It presents various Zhang dynamics (ZD) models by defining various Zhang functions (ZFs) in real and complex domains. It then provides theoretical analyses of such ZD models and illustrates their results. It also uses simulations to substantiate their efficacy and show the feasibility of the presented ZD approach (i.e., different ZFs leading to different ZD models), which is further applied to the repetitive motion planning (RMP) of redundant robots, showing its application potential.
Time Series Modelling of Syphilis Incidence in China from 2005 to 2012
Zhang, Xingyu; Zhang, Tao; Pei, Jiao; Liu, Yuanyuan; Li, Xiaosong; Medrano-Gracia, Pau
2016-01-01
Background The infection rate of syphilis in China has increased dramatically in recent decades, becoming a serious public health concern. Early prediction of syphilis is therefore of great importance for heath planning and management. Methods In this paper, we analyzed surveillance time series data for primary, secondary, tertiary, congenital and latent syphilis in mainland China from 2005 to 2012. Seasonality and long-term trend were explored with decomposition methods. Autoregressive integrated moving average (ARIMA) was used to fit a univariate time series model of syphilis incidence. A separate multi-variable time series for each syphilis type was also tested using an autoregressive integrated moving average model with exogenous variables (ARIMAX). Results The syphilis incidence rates have increased three-fold from 2005 to 2012. All syphilis time series showed strong seasonality and increasing long-term trend. Both ARIMA and ARIMAX models fitted and estimated syphilis incidence well. All univariate time series showed highest goodness-of-fit results with the ARIMA(0,0,1)×(0,1,1) model. Conclusion Time series analysis was an effective tool for modelling the historical and future incidence of syphilis in China. The ARIMAX model showed superior performance than the ARIMA model for the modelling of syphilis incidence. Time series correlations existed between the models for primary, secondary, tertiary, congenital and latent syphilis. PMID:26901682
Incidence of social phobia and identification of its risk indicators: a model for prevention.
Acarturk, C; Smit, F; de Graaf, R; van Straten, A; ten Have, M; Cuijpers, P
2009-01-01
This study seeks to examine the incidence of social phobia in the general population and to establish a number of risk indicators. Data were derived from the Netherlands Mental Health Survey and Incidence Study (NEMESIS) which is a population based prospective study (n=7076). A sample of adults aged 18-64 years (n=5618) were re-interviewed 1 year later using Composite International Diagnostic Interview (CIDI). The 12-month incidence of DSM-III-R social phobia was 1.0%. Low education, low mastery, low self-esteem, emotional neglect in childhood and ongoing difficulties were found to be risk indicators. After including other mental disorders as risk indicators in the model, the incidence was found to be more common among those with low mastery, major depression, subthreshold social phobia, emotional neglect, negative life events, and low education. The incidence of social phobia can be predicted relatively well with psychosocial variables and comorbidity.
Zhang, Shou-ping; Xin, Xiao-kang
2017-07-01
Identification of pollutant sources for river pollution incidents is an important and difficult task in the emergency rescue, and an intelligent optimization method can effectively compensate for the weakness of traditional methods. An intelligent model for pollutant source identification has been established using the basic genetic algorithm (BGA) as an optimization search tool and applying an analytic solution formula of one-dimensional unsteady water quality equation to construct the objective function. Experimental tests show that the identification model is effective and efficient: the model can accurately figure out the pollutant amounts or positions no matter single pollution source or multiple sources. Especially when the population size of BGA is set as 10, the computing results are sound agree with analytic results for a single source amount and position identification, the relative errors are no more than 5 %. For cases of multi-point sources and multi-variable, there are some errors in computing results for the reasons that there exist many possible combinations of the pollution sources. But, with the help of previous experience to narrow the search scope, the relative errors of the identification results are less than 5 %, which proves the established source identification model can be used to direct emergency responses.
A spatial model to predict the incidence of neural tube defects
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Li Lianfa
2012-11-01
Full Text Available Abstract Background Environmental exposure may play an important role in the incidences of neural tube defects (NTD of birth defects. Their influence on NTD may likely be non-linear; few studies have considered spatial autocorrelation of residuals in the estimation of NTD risk. We aimed to develop a spatial model based on generalized additive model (GAM plus cokriging to examine and model the expected incidences of NTD and make the inference of the incidence risk. Methods We developed a spatial model to predict the expected incidences of NTD at village level in Heshun County, Shanxi Province, China, a region with high NTD cases. GAM was used to establish linear and non-linear relationships between local covariates and the expected NTD incidences. We examined the following village-level covariates in the model: projected coordinates, soil types, lithodological classes, distance to watershed, rivers, faults and major roads, annual average fertilizer uses, fruit and vegetable production, gross domestic product, and the number of doctors. The residuals from GAM were assumed to be spatially auto-correlative and cokriged with regional residuals to improve the prediction. Our approach was compared with three other models, universal kriging, generalized linear regression and GAM. Cross validation was conducted for validation. Results Our model predicted the expected incidences of NTD well, with a good CV R2 of 0.80. Important predictive factors included the fertilizer uses, locations of the centroid of each village, the shortest distance to rivers and faults and lithological classes with significant spatial autocorrelation of residuals. Our model out-performed the other three methods by 16% or more in term of R2. Conclusions The variance explained by our model was approximately 80%. This modeling approach is useful for NTD epidemiological studies and intervention planning.
Settlement Relocation Modeling: Reacting to Merapi’s Eruption Incident
Pramitasari, A.; Buchori, I.
2018-02-01
Merapi eruption has made severe damages in Central Java Province. Klaten was one of the most affected area, specifically in Balerante Village. This research is made to comprehend GIS model on finding alternative locations for impacted settlement in hazardous zones of eruption. The principal objective of the research study is to identify and analyze physical condition, community characteristics, and local government regulation related to settlements relocation plan for impacted area of eruption. The output is location map which classified into four categories, i.e. not available, available with low accessibility, available with medium accessibility, and available with high accessibility.
Dynamics of a Delayed HIV-1 Infection Model with Saturation Incidence Rate and CTL Immune Response
Guo, Ting; Liu, Haihong; Xu, Chenglin; Yan, Fang
2016-12-01
In this paper, we investigate the dynamics of a five-dimensional virus model incorporating saturation incidence rate, CTL immune response and three time delays which represent the latent period, virus production period and immune response delay, respectively. We begin this model by proving the positivity and boundedness of the solutions. Our model admits three possible equilibrium solutions, namely the infection-free equilibrium E0, the infectious equilibrium without immune response E1 and the infectious equilibrium with immune response E2. Moreover, by analyzing corresponding characteristic equations, the local stability of each of the feasible equilibria and the existence of Hopf bifurcation at the equilibrium point E2 are established, respectively. Further, by using fluctuation lemma and suitable Lyapunov functionals, it is shown that E0 is globally asymptotically stable when the basic reproductive numbers for viral infection R0 is less than unity. When the basic reproductive numbers for immune response R1 is less than unity and R0 is greater than unity, the equilibrium point E1 is globally asymptotically stable. Finally, some numerical simulations are carried out for illustrating the theoretical results.
Anwar, Mohammad Y; Lewnard, Joseph A; Parikh, Sunil; Pitzer, Virginia E
2016-11-22
Malaria remains endemic in Afghanistan. National control and prevention strategies would be greatly enhanced through a better ability to forecast future trends in disease incidence. It is, therefore, of interest to develop a predictive tool for malaria patterns based on the current passive and affordable surveillance system in this resource-limited region. This study employs data from Ministry of Public Health monthly reports from January 2005 to September 2015. Malaria incidence in Afghanistan was forecasted using autoregressive integrated moving average (ARIMA) models in order to build a predictive tool for malaria surveillance. Environmental and climate data were incorporated to assess whether they improve predictive power of models. Two models were identified, each appropriate for different time horizons. For near-term forecasts, malaria incidence can be predicted based on the number of cases in the four previous months and 12 months prior (Model 1); for longer-term prediction, malaria incidence can be predicted using the rates 1 and 12 months prior (Model 2). Next, climate and environmental variables were incorporated to assess whether the predictive power of proposed models could be improved. Enhanced vegetation index was found to have increased the predictive accuracy of longer-term forecasts. Results indicate ARIMA models can be applied to forecast malaria patterns in Afghanistan, complementing current surveillance systems. The models provide a means to better understand malaria dynamics in a resource-limited context with minimal data input, yielding forecasts that can be used for public health planning at the national level.
Transfer Function Identification Using Orthogonal Fourier Transform Modeling Functions
Morelli, Eugene A.
2013-01-01
A method for transfer function identification, including both model structure determination and parameter estimation, was developed and demonstrated. The approach uses orthogonal modeling functions generated from frequency domain data obtained by Fourier transformation of time series data. The method was applied to simulation data to identify continuous-time transfer function models and unsteady aerodynamic models. Model fit error, estimated model parameters, and the associated uncertainties were used to show the effectiveness of the method for identifying accurate transfer function models from noisy data.
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Peter Scarborough
2016-11-01
Full Text Available Abstract Background The DisMod II model is designed to estimate epidemiological parameters on diseases where measured data are incomplete and has been used to provide estimates of disease incidence for the Global Burden of Disease study. We assessed the external validity of the DisMod II model by comparing modelled estimates of the incidence of first acute myocardial infarction (AMI in England in 2010 with estimates derived from a linked dataset of hospital records and death certificates. Methods Inputs for DisMod II were prevalence rates of ever having had an AMI taken from a population health survey, total mortality rates and AMI mortality rates taken from death certificates. By definition, remission rates were zero. We estimated first AMI incidence in an external dataset from England in 2010 using a linked dataset including all hospital admissions and death certificates since 1998. 95 % confidence intervals were derived around estimates from the external dataset and DisMod II estimates based on sampling variance and reported uncertainty in prevalence estimates respectively. Results Estimates of the incidence rate for the whole population were higher in the DisMod II results than the external dataset (+54 % for men and +26 % for women. Age-specific results showed that the DisMod II results over-estimated incidence for all but the oldest age groups. Confidence intervals for the DisMod II and external dataset estimates did not overlap for most age groups. Conclusion By comparison with AMI incidence rates in England, DisMod II did not achieve external validity for age-specific incidence rates, but did provide global estimates of incidence that are of similar magnitude to measured estimates. The model should be used with caution when estimating age-specific incidence rates.
An Approach to Modeling the Impact of Traffic Incident on Urban Expressway
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Yaping Li
2015-01-01
Full Text Available To identify network bottlenecks of urban expressway effectively is a foundational work for improving network traffic condition and preventing traffic congestion. This study proposes a methodology to estimate the impact of traffic incident on urban expressway on the basis of modified cell transmission model. The metastable state was taken into account in the proposed method to reflect the actual operating state of traffic flow on urban expressway as much as possible. Regarding the location of traffic incident, the method of cell restructuring settings was discussed. We then proceed to introduce a new concept of the effected length in a given time period as the evaluation indicator to directly depict the influence of traffic incident. The proposed method was tested on a 6516-meter urban expressway section of west second ring road in Beijing. The simulation results indicated that the proposed methodology performs well to predict the impact of traffic incident on urban expressway.
Age-period-cohort modelling of breast cancer incidence in the Nordic countries
DEFF Research Database (Denmark)
Rostgaard, K; Vaeth, M; Holst, H
2001-01-01
The Nordic countries have experienced a steady increase in breast cancer incidence throughout the past 35 years. We analysed the incidence in Denmark, Finland, Norway and Sweden during the period 1958 to 1992 using age-period-cohort models and taking the systematic mammography screening...... in breast cancer incidence seen in the Nordic countries. The widespread practice of neglecting the period effects in age-period-cohort analysis of time trends in breast cancer incidence therefore probably needs reconsideration. A key finding was that Danish women born in the 20th century seem to have been...... exposed to an increasing load of cohort borne breast cancer risk factors not experienced to the same extent by Norwegian women, whereas they were seemingly subjected to the same period effects....
Age-period-cohort modelling of breast cancer incidence in the Nordic countries
DEFF Research Database (Denmark)
Rostgaard, K; Vaeth, M; Holst, H
2001-01-01
in breast cancer incidence seen in the Nordic countries. The widespread practice of neglecting the period effects in age-period-cohort analysis of time trends in breast cancer incidence therefore probably needs reconsideration. A key finding was that Danish women born in the 20th century seem to have been...... exposed to an increasing load of cohort borne breast cancer risk factors not experienced to the same extent by Norwegian women, whereas they were seemingly subjected to the same period effects.......The Nordic countries have experienced a steady increase in breast cancer incidence throughout the past 35 years. We analysed the incidence in Denmark, Finland, Norway and Sweden during the period 1958 to 1992 using age-period-cohort models and taking the systematic mammography screening...
APOL1 Genotype and Race Differences in Incident Albuminuria and Renal Function Decline.
Peralta, Carmen A; Bibbins-Domingo, Kirsten; Vittinghoff, Eric; Lin, Feng; Fornage, Myriam; Kopp, Jeffrey B; Winkler, Cheryl A
2016-03-01
Variants in the APOL1 gene are associated with kidney disease in blacks. We examined associations of APOL1 with incident albuminuria and kidney function decline among 3030 young adults with preserved GFR in the Coronary Artery Risk Development in Young Adults (CARDIA) study. eGFR by cystatin C (eGFRcys) and albumin-to-creatinine ratio were measured at scheduled examinations. Participants were white (n=1700), high-risk black (two APOL1 risk alleles, n=176), and low-risk black (zero/one risk allele, n=1154). Mean age was 35 years, mean eGFRcys was 107 ml/min per 1.73 m(2), and 13.2% of blacks had two APOL1 alleles. The incidence rate per 1000 person-years (95% confidence interval) for albuminuria over 15 years was 15.6 (10.6-22.1) for high-risk blacks, 7.8 (6.4-9.4) for low-risk blacks, and 3.9 (3.1-4.8) for whites. Compared with whites, the odds ratio (95% confidence interval) for incident albuminuria was 5.71 (3.64-8.94) for high-risk blacks and 2.32 (1.73-3.13) for low-risk blacks. Adjustment for risk factors attenuated the difference between low-risk blacks and whites (odds ratio 1.21, 95% confidence interval 0.86-1.71). After adjustment, high-risk blacks had a 0.45% faster yearly eGFRcys decline over 9.3 years compared with whites. Low-risk blacks also had a faster yearly eGFRcys decline compared with whites, but this difference was attenuated after adjustment for risk factors and socioeconomic position. In conclusion, blacks with two APOL1 risk alleles had the highest risk for albuminuria and eGFRcys decline in young adulthood, whereas disparities between low-risk blacks and whites were related to differences in traditional risk factors. Copyright © 2016 by the American Society of Nephrology.
Watson, Willie R.; Jones, Michael G.; Tanner, Sharon E.; Parrott, Tony L.
1995-01-01
A propagation model method for extracting the normal incidence impedance of an acoustic material installed as a finite length segment in a wall of a duct carrying a nonprogressive wave field is presented. The method recasts the determination of the unknown impedance as the minimization of the normalized wall pressure error function. A finite element propagation model is combined with a coarse/fine grid impedance plane search technique to extract the impedance of the material. Results are presented for three different materials for which the impedance is known. For each material, the input data required for the prediction scheme was computed from modal theory and then contaminated by random error. The finite element method reproduces the known impedance of each material almost exactly for random errors typical of those found in many measurement environments. Thus, the method developed here provides a means for determining the impedance of materials in a nonprogressirve wave environment such as that usually encountered in a commercial aircraft engine and most laboratory settings.
Abbasi, Ali; Bakker, Stephan J. L.; Corpeleijn, Eva; van der A, Daphne L.; Gansevoort, Ron T.; Gans, Rijk O. B.; Peelen, Linda M.; van der Schouw, Yvonne T.; Stolk, Ronald P.; Navis, Gerjan; Spijkerman, Annemieke M. W.; Beulens, Joline W. J.
2012-01-01
Background: Liver function tests might predict the risk of type 2 diabetes. An independent study evaluating utility of these markers compared with an existing prediction model is yet lacking. Methods and Findings: We performed a case-cohort study, including random subcohort (6.5%) from 38,379
Directory of Open Access Journals (Sweden)
Davi Casale Aragon
Full Text Available Abstract: INTRODUCTION: The monthly incidence of snakebites from 2007 to 2014 in the State of São Paulo, Brazil, was assessed. METHODS: A statistical model based on the discrete double Poisson distribution was proposed, including pairs of sine and cosine functions of time to account for seasonality and autoregressive terms. RESULTS: The analysis indicated a slight increase in the incidence of snakebites. The inclusion of two pairs of trigonometric functions seemed to be relevant in the model adjustment, given the seasonal pattern of the data. CONCLUSIONS: The snakebites occurred predominantly during the warm season, from November to April.
International Nuclear Information System (INIS)
Heidenreich, W.F.; Jacob, P.; Paretzke, H.G.
1997-01-01
We derive explizit hazard functions for the clonal expansion model in the ''exact formulation'' and in the ''epidemiological approximation'' for the spontaneous rate and for short-time exposure. We investigate which combination of the biological parameters can be determined from the incidence function, and which cannot. We then analyze the incidence data of all solid tumors of atomic bomb survivors (1958-1987). We restrict ourselves to adults at exposure (>20 years) and to attained age <80 years, and we consider the two cities (Hiroshima and Nagasaki) and the two sexes separately. With four parameters, we find good fits in each case, comparable to the quality of fit of epidemiological age-at-exposure and age-attained models used for comparison. The parameters which describe the spontaneous risk agree very well for the two cities, while they are quite different for the two sexes. The apparent flattening of the risk for elderly men can be described with the exact formulation of the clonal expansion model, but may be due to other causes than the mechanisms modeled. The dose-response parameters differ by more than two standard deviations (factor 2 to 3) between the two cities, when considering the same sex. They are bigger for the men of Nagasaki and the women of Hiroshima. One example for model application to tumors of specific organs (men's lung tumor) is considered. (orig.). With 15 figs., 4 tabs
Energy Technology Data Exchange (ETDEWEB)
Armenta-Deu, C. (Universidad Complutense de Madrid (ES). Facultad Fisicas); Lukac, B. (University of T. and C. Zilina (CS))
1991-01-01
The radiation transmittance and absorptance of materials vary according to the angle of incidence of the incoming solar radiation. Therefore, the efficiency of most solar converters (thermal or photovoltaic) is a function of the sun's position through the angle of incidence. This problem may be taken account of by the Incidence Angle Modifier, which is considered in this paper. An analytic expression for the incidence angle modifier, based on meteorological data or on geographic and geometric parameters, has been developed; this expression includes the effect of beam and diffuse radiation as well as the global influence. A comparison between measured data and these computed from our model has given a very good correlation, the results being within {+-}3% for horizontal and titled planes, and within {+-}7% for vertical surfaces, on average. The method also computes the collectible solar energy within a 5% error for thresholds up to 300Wm{sup -2}. The method has been validated for more than 30 locations in south and west Europe. (author).
Alegana, Victor A; Atkinson, Peter M; Wright, Jim A; Kamwi, Richard; Uusiku, Petrina; Katokele, Stark; Snow, Robert W; Noor, Abdisalan M
2013-12-01
As malaria transmission declines, it becomes increasingly important to monitor changes in malaria incidence rather than prevalence. Here, a spatio-temporal model was used to identify constituencies with high malaria incidence to guide malaria control. Malaria cases were assembled across all age groups along with several environmental covariates. A Bayesian conditional-autoregressive model was used to model the spatial and temporal variation of incidence after adjusting for test positivity rates and health facility utilisation. Of the 144,744 malaria cases recorded in Namibia in 2009, 134,851 were suspected and 9893 were parasitologically confirmed. The mean annual incidence based on the Bayesian model predictions was 13 cases per 1000 population with the highest incidence predicted for constituencies bordering Angola and Zambia. The smoothed maps of incidence highlight trends in disease incidence. For Namibia, the 2009 maps provide a baseline for monitoring the targets of pre-elimination. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.
The Dynamical Behaviors in a Stochastic SIS Epidemic Model with Nonlinear Incidence.
Rifhat, Ramziya; Ge, Qing; Teng, Zhidong
2016-01-01
A stochastic SIS-type epidemic model with general nonlinear incidence and disease-induced mortality is investigated. It is proved that the dynamical behaviors of the model are determined by a certain threshold value [Formula: see text]. That is, when [Formula: see text] and together with an additional condition, the disease is extinct with probability one, and when [Formula: see text], the disease is permanent in the mean in probability, and when there is not disease-related death, the disease oscillates stochastically about a positive number. Furthermore, when [Formula: see text], the model admits positive recurrence and a unique stationary distribution. Particularly, the effects of the intensities of stochastic perturbation for the dynamical behaviors of the model are discussed in detail, and the dynamical behaviors for the stochastic SIS epidemic model with standard incidence are established. Finally, the numerical simulations are presented to illustrate the proposed open problems.
Extinction and Ergodic Property of Stochastic SIS Epidemic Model with Nonlinear Incidence Rate
Directory of Open Access Journals (Sweden)
Qixing Han
2013-01-01
Full Text Available We investigate a stochastic SIS model with nonlinear incidence rate. We show that there exists a unique nonnegative solution to the system, and condition for the infectious individuals I(t to be extinct is given. Moreover, we prove that the system has ergodic property. Finally, computer simulations are carried out to verify our results.
Dependence of ECH deposition profile on the modeling of incident wave energy
International Nuclear Information System (INIS)
Kritz, A.H.; Hsuan, H.; Matsuda, K.
1986-06-01
The ray tracing code, TORAY, is used to investigate the importance of modeling assumptions utilized in describing Electron Cyclotron Heating (ECH). In particular, we examine the dependence of the ECH deposition profile on the antenna pattern. We demonstrate that different assumptions for representing the incident wave energy by a finite number of rays lead to significantly different results for the energy deposition profile
Implementation of the critical points model in a SFM-FDTD code working in oblique incidence
Energy Technology Data Exchange (ETDEWEB)
Hamidi, M; Belkhir, A; Lamrous, O [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri, Tizi-Ouzou (Algeria); Baida, F I, E-mail: omarlamrous@mail.ummto.dz [Departement d' Optique P.M. Duffieux, Institut FEMTO-ST UMR 6174 CNRS Universite de Franche-Comte, 25030 Besancon Cedex (France)
2011-06-22
We describe the implementation of the critical points model in a finite-difference-time-domain code working in oblique incidence and dealing with dispersive media through the split field method. Some tests are presented to validate our code in addition to an application devoted to plasmon resonance of a gold nanoparticles grating.
CSIR Research Space (South Africa)
Mbecke, ZP
2010-07-01
Full Text Available This paper is based on an in-progress PhD thesis themed: “Modeling the Differential Incidence of Child Abuse, Neglect and Exploitation in Poor Households in South Africa”. The thesis argues that the gaps and shortcomings in the prevention of child...
Directory of Open Access Journals (Sweden)
Mirabelli Maria C
2012-03-01
Full Text Available Abstract Background Specific occupations are associated with adverse respiratory health. Inhalation exposures encountered in these jobs may place workers at risk of new-onset respiratory disease. Methods We analyzed data from 8,967 participants from the Atherosclerosis Risk in Communities (ARIC study, a longitudinal cohort study. Participants included in this analysis were free of chronic cough and phlegm, wheezing, asthma, chronic bronchitis, emphysema, and other chronic lung conditions at the baseline examination, when they were aged 45-64 years. Using data collected in the baseline and first follow-up examination, we evaluated associations between occupation and the three-year incidence of cough, phlegm, wheezing, and airway obstruction and changes in forced expiratory volume in one second (FEV1 and forced vital capacity (FVC measured by spirometry. All associations were adjusted for age, cigarettes per day, race, smoking status, and study center. Results During the approximately three-year follow-up, the percentage of participants developing chronic cough was 3%; chronic phlegm, 3%; wheezing, 3%; and airway obstruction, defined as FEV1 1/FVC 1 and FVC were 56 mL and 66 mL, respectively, among men and 40 mL and 52 mL, respectively, among women. Relative to a referent category of managerial and administrative support occupations, elevated risks of new-onset chronic cough and chronic phlegm were observed for mechanics and repairers (chronic cough: RR: 1.81, 95% CI: 1.02, 3.21; chronic phlegm: RR: 2.10, 95% CI: 1.23, 3.57 and cleaning and building service workers (chronic cough: RR: 1.85, 95% CI: 1.01, 3.37; chronic phlegm: RR: 2.28, 95% CI: 1.27, 4.08. Despite the elevated risk of new-onset symptoms, employment in cleaning and building services was associated with attenuated lung function decline, particularly among men, who averaged annual declines in FEV1 and FVC of 14 mL and 23 mL, respectively, less than the declines observed in the
Hiller, Josh; Vallejo, Celeste; Betthauser, Leo; Keesling, James
2017-03-01
We investigate and classify several patterns in cancer incidence and relative risk data which persist across different countries and multiple published studies. We then explore biological hypotheses as well as many mathematical models in the literature that attempt to explain these patterns. A general modeling framework is presented which is general enough to model most of observed behaviors. It is our belief that this model has sufficient flexibility to be adapted to new information as it is discovered. As one application of this framework, we give a model for the effect of aging on the process of carcinogenesis. Copyright © 2016 Elsevier Ltd. All rights reserved.
Ahmadi-Abhari, Sara; Guzman-Castillo, Maria; Bandosz, Piotr; Shipley, Martin J; Muniz-Terrera, Graciela; Singh-Manoux, Archana; Kivimäki, Mika; Steptoe, Andrew; Capewell, Simon; O'Flaherty, Martin; Brunner, Eric J
2017-07-05
Objective To forecast dementia prevalence with a dynamic modelling approach that integrates calendar trends in dementia incidence with those for mortality and cardiovascular disease. Design Modelling study. Setting General adult population of England and Wales. Participants The English Longitudinal Study of Ageing (ELSA) is a representative panel study with six waves of data across 2002-13. Men and women aged 50 or more years, selected randomly, and their cohabiting partners were recruited to the first wave of ELSA (2002-03). 11392 adults participated (response rate 67%). To maintain representativeness, refreshment participants were recruited to the study at subsequent waves. The total analytical sample constituted 17 906 people. Constant objective criteria based on cognitive and functional impairment were used to ascertain dementia cases at each wave. Main outcome measures To estimate calendar trends in dementia incidence, correcting for bias due to loss to follow-up of study participants, a joint model of longitudinal and time-to-event data was fitted to ELSA data. To forecast future dementia prevalence, the probabilistic Markov model IMPACT-BAM (IMPACT-Better Ageing Model) was developed. IMPACT-BAM models transitions of the population aged 35 or more years through states of cardiovascular disease, cognitive and functional impairment, and dementia, to death. It enables prediction of dementia prevalence while accounting for the growing pool of susceptible people as a result of increased life expectancy and the competing effects due to changes in mortality, and incidence of cardiovascular disease. Results In ELSA, dementia incidence was estimated at 14.3 per 1000 person years in men and 17.0/1000 person years in women aged 50 or more in 2010. Dementia incidence declined at a relative rate of 2.7% (95% confidence interval 2.4% to 2.9%) for each year during 2002-13. Using IMPACT-BAM, we estimated there were approximately 767 000 (95% uncertainty
Shen, Xing-Rong; Feng, Rui; Chai, Jing; Cheng, Jing; Wang, De-Bin
2014-01-01
Large scale secular registry or surveillance systems have been accumulating vast data that allow mathematical modeling of cancer incidence and mortality rates. Most contemporary models in this regard use time series and APC (age-period-cohort) methods and focus primarily on predicting or analyzing cancer epidemiology with little attention being paid to implications for designing cancer registry, surveillance or evaluation initiatives. This research models age-specific cancer incidence rates using logistic growth equations and explores their performance under different scenarios of data completeness in the hope of deriving clues for reshaping relevant data collection. The study used China Cancer Registry Report 2012 as the data source. It employed 3-parameter logistic growth equations and modeled the age-specific incidence rates of all and the top 10 cancers presented in the registry report. The study performed 3 types of modeling, namely full age-span by fitting, multiple 5-year- segment fitting and single-segment fitting. Measurement of model performance adopted adjusted goodness of fit that combines sum of squred residuals and relative errors. Both model simulation and performance evalation utilized self-developed algorithms programed using C# languade and MS Visual Studio 2008. For models built upon full age-span data, predicted age-specific cancer incidence rates fitted very well with observed values for most (except cervical and breast) cancers with estimated goodness of fit (Rs) being over 0.96. When a given cancer is concerned, the R valuae of the logistic growth model derived using observed data from urban residents was greater than or at least equal to that of the same model built on data from rural people. For models based on multiple-5-year-segment data, the Rs remained fairly high (over 0.89) until 3-fourths of the data segments were excluded. For models using a fixed length single-segment of observed data, the older the age covered by the corresponding
Visser, Marjolein; Goodpaster, Bret H; Kritchevsky, Stephen B; Newman, Anne B; Nevitt, Michael; Rubin, Susan M; Simonsick, Eleanor M; Harris, Tamara B
BACKGROUND: Lower muscle mass has been correlated with poor physical function; however, no studies have examined this relationship prospectively. This study aims to investigate whether low muscle mass, low muscle strength, and greater fat infiltration into the muscle predict incident mobility
Dynamic Behavior for an SIRS Model with Nonlinear Incidence Rate and Treatment
Directory of Open Access Journals (Sweden)
Junhong Li
2013-01-01
Full Text Available This paper considers an SIRS model with nonlinear incidence rate and treatment. It is assumed that susceptible and infectious individuals have constant immigration rates. We investigate the existence of equilibrium and prove the global asymptotical stable results of the endemic equilibrium. We then obtained that the model undergoes a Hopf bifurcation and existences a limit cycle. Some numerical simulations are given to illustrate the analytical results.
Rifhat, Ramziya; Wang, Lei; Teng, Zhidong
2017-09-01
In this paper, we investigate the dynamics of a class of periodic stochastic SIS epidemic models with general nonlinear incidence f(S , I) . Some sufficient conditions on the permanence in the mean and extinction of positive solutions with probability one are established. By using the Khasminskii's boundary periodic Markov processes, the existence of stochastic nontrivial periodic solution for the models is also obtained. The numerical simulations are given to illustrate the main theoretical results and some interesting conjectures are presented.
A Model for Relating Advertising Media Exposures to Purchase Incidence Behavior Patterns
Fred S. Zufryden
1987-01-01
A stochastic model is proposed to study the effect of advertising on consumer purchase dynamics by specifically relating the distribution of exposures, from a brand's media schedule, to brand purchase incidence behavior patterns over time. The approach is based on underlying individual consumer behavior assumptions that reflect the dynamics of exposures to advertising and brand purchase behavior, conditional on the level of advertising exposure received. Moreover, a population-based model is ...
International Nuclear Information System (INIS)
Regens, J.L.; Gunter, J.T.; Gupta, S.
2009-01-01
Homeland Security Presidential Directive no.5 (HSPD-5) Management of Domestic Incidents and Department of Homeland Security (DHS) Planning Guidance for Protection and Recovery Following Radiological Dispersal Device (RDD) and Improvised Nuclear Device (IND) Incidents underscore the need to delineate radiological emergency guidance applicable to remedial action and recovery following an RDD or IND incident. Rapid delineation of the population potentially exposed to ionizing radiation from fallout during terrorist incidents involving RDDs or low-yield nuclear devices (≤ 20 KT) is necessary for effective medical response and incident management as part of the recovery process. This paper illustrates the application of spatial interaction models to allocate population data for a representative U.S. urban area (≅1.3M people; 1,612.27 km 2 area) at a geographical scale relevant for accurately estimating risk given dose concentrations. Estimated total dose equivalents (TEDE) are calculated for isopleths moving away from the detonation point for typical release scenarios. Population is estimated within the TEDE zones using Euclidean distances between zip code polygon centroids generated in ArcGIS version 9.1 with distance decay determined by regression analysis to apportion origin-destination pairs to a population count and density matrix on a spatial basis for daytime and night-time release scenarios. (authors)
Analysis of an HIV/AIDS treatment model with a nonlinear incidence
International Nuclear Information System (INIS)
Cai Liming; Wu Jingang
2009-01-01
An HIV/AIDS treatment model with a nonlinear incidence is formulated. The infectious period is partitioned into the asymptotic and the symptomatic phases according to clinical stages. The constant recruitment rate, disease-induced death, drug therapies, as well as a nonlinear incidence, are incorporated into the model. The basic reproduction number R 0 of the model is determined by the method of next generation matrix. Mathematical analysis establishes that the global dynamics of the spread of the HIV infectious disease are completely determined by the basic reproduction number R 0 . If R 0 ≤1, the disease always dies out and the disease-free equilibrium is globally stable. If R 0 >1, the disease persists and the unique endemic equilibrium is globally asymptotically stable in the interior of the feasible region.
Modeling the incidence of citrus canker in leaves of the sweet orange variety ‘Pera’
Directory of Open Access Journals (Sweden)
Danielle da Silva Pompeu
2017-01-01
Full Text Available Citrus canker, caused by the bacterium Xanthomonas citri subsp. citri, is one of the most important diseases of citrus. The use of resistant genotypes plays an important role in the management and control of the disease and is the most environmentally sustainable approach to disease control. Citrus canker incidence was recorded in an experiment on nine genotypes of the sweet orange variety ‘Pera’ grafted on four rootstocks. The experiment was started in 2010 and the incidence of citrus canker on the leaves was recorded on a quarterly basis. The incidence data from the experiment were analyzed using a zero-inflated Beta regression model (RBIZ, which is the appropriate method to describe data with large numbers of zeros. Based on the residual analysis, the data fit the model well. The discrete component of the explanatory variable, rootstock, was not significant as a factor affecting the onset of disease, in contrast with the continuous component, genotype, which was significant in explaining the incidence of citrus canker.
Monteiro, Cláudio; Ferrari, Andres Di Leoni; Caramori, Paulo Ricardo Avancini; Carvalho, Luiz Antonio Ferreira; Siqueira, Dimytri Alexandre de Alvim; Thiago, Luiz Eduardo Koenig São; Perin, Marco; Lima, Valter C de; Guérios, Enio; Brito Junior, Fabio Sandoli De
2017-12-01
Transcatheter aortic valve implantation (TAVI) is a well-established procedure; however, atrioventricular block requiring permanent pacemaker implantation (PPI) is a common complication. To determine the incidence, predictors and clinical outcomes of PPI after TAVI, focusing on how PPI affects left ventricular ejection fraction (LVEF) after TAVI. The Brazilian Multicenter TAVI Registry included 819 patients submitted to TAVI due to severe aortic stenosis from 22 centers from January/2008 to January/2015. After exclusions, the predictors of PPI were assessed in 670 patients by use of multivariate regression. Analysis of the ROC curve was used to measure the ability of the predictors; p 50 mm Hg (OR, 1.86; 1.08-3.2; p = 0.025) were predictors of PPI. The estimated risk of PPI ranged from 4%, when none of those predictors was present, to 63%, in the presence of all of them. The model showed good ability to predict the need for PPI: 0.69 (95%CI: 0.64 - 0.74) in the ROC curve. The substudy of 287 echocardiograms during the 1-year follow-up showed worse LVEF course in patients submitted to PPI (p = 0.01). BRD prévio, gradiente aórtico médio > 50 mmHg e CoreValve® são preditores independentes de implante de MPD pós-TAVI. Ocorreu implante de MPD em aproximadamente 20% dos casos de TAVI, o que prolongou a internação hospitalar, mas não afetou a mortalidade. O implante de MPD afetou negativamente a FEVE pós-TAVI.
McCarthy, Linda C; Newcombe, Paul J; Whittaker, John C; Wurzelmann, John I; Fries, Michael A; Burnham, Nancy R; Cai, Gengqian; Stinnett, Sandra W; Trivedi, Trupti M; Xu, Chun-Fang
2012-09-01
To develop comprehensive predictive models for choroidal neovascularization (CNV) and geographic atrophy (GA) incidence within 3 years that can be applied realistically to clinical practice. Retrospective evaluation of data from a longitudinal study to develop and validate predictive models of CNV and GA. The predictive performance of clinical, environmental, demographic, and genetic risk factors was explored in regression models, using data from both eyes of 2011 subjects from the Age-Related Eye Disease Study (AREDS). The performance of predictive models was compared using 10-fold cross-validated receiver operating characteristic curves in the training data, followed by comparisons in an independent validation dataset (1410 AREDS subjects). Bayesian trial simulations were used to compare the usefulness of predictive models to screen patients for inclusion in prevention clinical trials. Logistic regression models that included clinical, demographic, and environmental factors had better predictive performance for 3-year CNV and GA incidence (area under the receiver operating characteristic curve of 0.87 and 0.89, respectively), compared with simple clinical criteria (AREDS simplified severity scale). Although genetic markers were associated significantly with 3-year CNV (CFH: Y402H; ARMS2: A69S) and GA incidence (CFH: Y402H), the inclusion of genetic factors in the models provided only marginal improvements in predictive performance. The logistic regression models combine good predictive performance with greater flexibility to optimize clinical trial design compared with simple clinical models (AREDS simplified severity scale). The benefit of including genetic factors to screen patients for recruitment to CNV prevention studies is marginal and is dependent on individual clinical trial economics. Copyright © 2012 Elsevier Inc. All rights reserved.
He, Fei; Hu, Zhi-jian; Zhang, Wen-chang; Cai, Lin; Cai, Guo-xi; Aoyagi, Kiyoshi
2017-01-01
It remains challenging to forecast local, seasonal outbreaks of influenza. The goal of this study was to construct a computational model for predicting influenza incidence. We built two computational models including an Autoregressive Distributed Lag (ARDL) model and a hybrid model integrating ARDL with a Generalized Regression Neural Network (GRNN), to assess meteorological factors associated with temporal trends in influenza incidence. The modelling and forecasting performance of these two ...
Global Stability of an Eco-Epidemiological Model with Time Delay and Saturation Incidence
Directory of Open Access Journals (Sweden)
Shuxue Mao
2011-01-01
Full Text Available We investigate a delayed eco-epidemiological model with disease in predator and saturation incidence. First, by comparison arguments, the permanence of the model is discussed. Then, we study the local stability of each equilibrium of the model by analyzing the corresponding characteristic equations and find that Hopf bifurcation occurs when the delay τ passes through a sequence of critical values. Next, by means of an iteration technique, sufficient conditions are derived for the global stability of the disease-free planar equilibrium and the positive equilibrium. Numerical examples are carried out to illustrate the analytical results.
Wei, Xiaodan; Liu, Lijun; Zhou, Wenshu
2017-03-01
In this paper, we study the global stability and attractivity of the endemic equilibrium for a network-based SIS epidemic model with nonmonotone incidence rate. The model was introduced in Li (2015). We prove that the endemic equilibrium is globally asymptotically stable if α (a parameter of this model) is sufficiently large, and is globally attractive if the transmission rate λ satisfies λ/λc ∈(1 , 2 ] , where λc is the epidemic threshold. Some numerical experiments are also presented to illustrate the theoretical results.
Traveling waves in a delayed SIR model with nonlocal dispersal and nonlinear incidence
Zhang, Shou-Peng; Yang, Yun-Rui; Zhou, Yong-Hui
2018-01-01
This paper is concerned with traveling waves of a delayed SIR model with nonlocal dispersal and a general nonlinear incidence. The existence and nonexistence of traveling waves of the system are established respectively by Schauder's fixed point theorem and two-sided Laplace transform. It is also shown that the spread speed c is influenced by the dispersal rate of the infected individuals and the delay τ.
Fan, Kuangang; Zhang, Yan; Gao, Shujing; Wei, Xiang
2017-09-01
A class of SIR epidemic model with generalized nonlinear incidence rate is presented in this paper. Temporary immunity and stochastic perturbation are also considered. The existence and uniqueness of the global positive solution is achieved. Sufficient conditions guaranteeing the extinction and persistence of the epidemic disease are established. Moreover, the threshold behavior is discussed, and the threshold value R0 is obtained. We show that if R0 1, then the system remains permanent in the mean.
Hierarchical models and functional traits
van Loon, E.E.; Shamoun-Baranes, J.; Sierdsema, H.; Bouten, W.; Cramer, W.; Badeck, F.; Krukenberg, B.; Klotz, S.; Kühn, I.; Schweiger, O.; Böhning-Gaese, K.; Schaefer, H.-C.; Kissling, D.; Brandl, R.; Brändle, M.; Fricke, R.; Leuschner, C.; Buschmann, H.; Köckermann, B.; Rose, L.
2006-01-01
Hierarchical models for animal abundance prediction are conceptually elegant. They are generally more parsimonous than non-hierarchical models derived from the same data, give relatively robust predictions and automatically provide consistent output at multiple (spatio-temporal) scales. Another
Projecting cancer incidence using age-period-cohort models incorporating restricted cubic splines.
Rutherford, Mark J; Thompson, John R; Lambert, Paul C
2012-11-05
Age-period-cohort models provide a useful method for modeling incidence and mortality rates. There is great interest in estimating the rates of disease at given future time-points in order that plans can be made for the provision of the required future services. In the setting of using age-period-cohort models incorporating restricted cubic splines, a new technique for projecting incidence is proposed. The new technique projects the period and cohort terms linearly from 10 years within the range of the available data in order to give projections that are based on recent trends. The method is validated via a comparison with existing methods in the setting of Finnish cancer registry data. The reasons for the improvements seen for the newly proposed method are twofold. Firstly, improvements are seen due to the finer splitting of the timescale to give a more continuous estimate of the incidence rate. Secondly, the new method uses more recent trends to dictate the future projections than previously proposed methods.
DEFF Research Database (Denmark)
Jeong, Cheol-Ho
2011-01-01
resistivity and the absorber thickness on the difference between the two surface reaction models are examined and discussed. For a porous absorber backed by a rigid surface, the local reaction models give errors of less than 10% if the thickness exceeds 120 mm for a flow resistivity of 5000 Nm-4s. As the flow......Room surfaces have been extensively modeled as locally reacting in room acoustic predictions although such modeling could yield significant errors under certain conditions. Therefore, this study aims to propose a guideline for adopting the local reaction assumption by comparing predicted random...... incidence acoustical characteristics of typical building elements made of porous materials assuming extended and local reaction. For each surface reaction, five well-established wave propagation models, the Delany-Bazley, Miki, Beranek, Allard-Champoux, and Biot model, are employed. Effects of the flow...
Directory of Open Access Journals (Sweden)
Andrew I. Chin
2017-09-01
Discussion: More than 50% of incident HD patients with RKF have adequate kidney urea clearance to be considered for 2-times weekly HD. When additionally ultrafiltration volume and blood pressure stability are taken into account, more than one-fourth of the total cohort could optimally start HD in an incremental fashion.
Directory of Open Access Journals (Sweden)
Tengiz Mdzinarishvili
2009-12-01
Full Text Available A simple, computationally efficient procedure for analyses of the time period and birth cohort effects on the distribution of the age-specific incidence rates of cancers is proposed. Assuming that cohort effects for neighboring cohorts are almost equal and using the Log-Linear Age-Period-Cohort Model, this procedure allows one to evaluate temporal trends and birth cohort variations of any type of cancer without prior knowledge of the hazard function. This procedure was used to estimate the influence of time period and birth cohort effects on the distribution of the age-specific incidence rates of first primary, microscopically confirmed lung cancer (LC cases from the SEER9 database. It was shown that since 1975, the time period effect coefficients for men increase up to 1980 and then decrease until 2004. For women, these coefficients increase from 1975 up to 1990 and then remain nearly constant. The LC birth cohort effect coefficients for men and women increase from the cohort of 1890–94 until the cohort of 1925–29, then decrease until the cohort of 1950–54 and then remain almost unchanged. Overall, LC incidence rates, adjusted by period and cohort effects, increase up to the age of about 72–75, turn over, and then fall after the age of 75–78. The peak of the adjusted rates in men is around the age of 77–78, while in women, it is around the age of 72–73. Therefore, these results suggest that the age distribution of the incidence rates in men and women fall at old ages.
Lennquist Montán, K; Hreckovski, B; Dobson, B; Örtenwall, P; Montán, C; Khorram-Manesh, A; Lennquist, S
2014-08-01
The need for and benefit of simulation models for interactive training of the response to major incidents and disasters has been increasingly recognized during recent years. One of the advantages with such models is that all components of the chain of response can be trained simultaneously. This includes the important communication/coordination between different units, which has been reported as the most common cause of failure. Very few of the presently available simulation models have been suitable for the simultaneous training of decision-making on all levels of the response. In this study, a new simulation model, originally developed for the scientific evaluation of methodology, was adapted to and developed for the postgraduate courses in Medical Response to Major Incidents (MRMI) organized under the auspices of the European Society for Trauma and Emergency Surgery (ESTES). The aim of the present study was to describe this development process, the model it resulted in, and the evaluation of this model. The simulation model was based on casualty cards giving all information normally available for the triage and primary management of traumatized patients. The condition of the patients could be changed by the instructor according to the time passed since the time of injury and treatments performed. Priority of the casualties as well as given treatments could be indicated on the cards by movable markers, which also gave the time required for every treatment. The exercises were run with real consumption of time and resources for all measures performed. The magnetized cards were moved by the trainees through the scene, through the transport lines, and through the hospitals where all functions were trained. For every patient was given the definitive diagnosis and the times within certain treatments had to be done to avoid preventable mortality and complications, which could be related to trauma-scores. The methodology was tested in nine MRMI courses with a total of
DEFF Research Database (Denmark)
Rossing, K; Jacobsen, P; Rossing, P
1998-01-01
OBJECTIVE: To evaluate trends in visual acuity and the cumulative incidence of diabetic retinopathy in a clinic-based observational follow-up study. RESEARCH DESIGN AND METHODS: All patients visiting Hvidore Hospital in 1984 whose diagnosis of IDDM had been made before 41 years of age and between...... = 113). RESULTS: Fifteen years after diabetes onset, the visual acuity was significantly improved in patients with increasing calendar year of the disease onset. The median (interquartile range) visual acuity was 1.0 (0.8-1.0), 1.0(0.9-1.0), and 1.0 (1.0-1.0) in groups A, B, and C, respectively (P ....01 overall; P = 0.28 for group A vs. group B; and P visual acuity of 1.0 in groups A, B, and C, respectively. The cumulative incidence (+/-SEM), expressed as a percentage and calculated according to the life-table method, of proliferative...
DEFF Research Database (Denmark)
Rossing, K; Jacobsen, P; Rossing, P
1998-01-01
OBJECTIVE: To evaluate trends in visual acuity and the cumulative incidence of diabetic retinopathy in a clinic-based observational follow-up study. RESEARCH DESIGN AND METHODS: All patients visiting Hvidore Hospital in 1984 whose diagnosis of IDDM had been made before 41 years of age and between...... retinopathy, maculopathy, and laser-treated retinopathy 15 years after onset of diabetes were, respectively, 13+/-3, 11+/-3, and 12+/-3 in group A; 16+/-3, 12+/-3, and 21+/-4 in group B; 11+/-3, 5+/-2, and 12+/-3 in group C, respectively (NS). The development of proliferative retinopathy was associated...... with the degree of retinopathy and albuminuria at baseline and the mean HbA1c during follow-up. CONCLUSIONS: The study revealed an improvement in visual acuity with increasing calendar year of diabetes onset but an unchanged cumulative incidence of diabetic retinopathy....
Sun, Kai; Hong, Fu; Wang, Yun; Agopian, Vatche G; Yan, Min; Busuttil, Ronald W; Steadman, Randolph H; Xia, Victor W
2017-11-01
Although the hemodynamic benefits of venovenous bypass (VVB) during liver transplantation (LT) are well appreciated, the impact of VVB on posttransplant renal function is uncertain. The aim of this study was to determine if VVB was associated with a lower incidence of posttransplant acute kidney injury (AKI). Medical records of adult (≥18 years) patients who underwent primary LT between 2004 and 2014 at a tertiary hospital were reviewed. Patients who required pretransplant renal replacement therapy and intraoperative piggyback technique were excluded. Patients were divided into 2 groups, VVB and non-VVB. AKI, determined by the Acute Kidney Injury Network criteria, was compared between the 2 groups. Propensity match was used to control selection bias that occurred before VVB and multivariable logistic regression was used to control confounding factors during and after VVB. Of 1037 adult patients who met the study inclusion criteria, 247 (23.8%) received VVB. A total of 442 patients (221 patients in each group) were matched. Aftermatch patients were further divided according to a predicted probability AKI model using preoperative creatinine (Cr), VVB, and intraoperative variables into 2 subgroups: normal and compromised pretransplant renal functions. In patients with compromised pretransplant renal function (Cr ≥1.2 mg/dL), the incidence of AKI was significantly lower in the VVB group compared with the non-VVB group (37.2% vs 50.8%; P = .033). VVB was an independent risk factor negatively associated with AKI (odds ratio, 0.1; 95% confidence interval, 0.1-0.4; P = .001). Renal replacement in 30 days and 1-year recipient mortality were not significantly different between the 2 groups. The incidence of posttransplant AKI was not significantly different between the 2 groups in patients with normal pretransplant renal function (Cr renal function. Further studies to assess the role of intraoperative VVB in posttransplant AKI are warranted.
A forecasting model for dengue incidence in the District of Gampaha, Sri Lanka.
Withanage, Gayan P; Viswakula, Sameera D; Nilmini Silva Gunawardena, Y I; Hapugoda, Menaka D
2018-04-24
Dengue is one of the major health problems in Sri Lanka causing an enormous social and economic burden to the country. An accurate early warning system can enhance the efficiency of preventive measures. The aim of the study was to develop and validate a simple accurate forecasting model for the District of Gampaha, Sri Lanka. Three time-series regression models were developed using monthly rainfall, rainy days, temperature, humidity, wind speed and retrospective dengue incidences over the period January 2012 to November 2015 for the District of Gampaha, Sri Lanka. Various lag times were analyzed to identify optimum forecasting periods including interactions of multiple lags. The models were validated using epidemiological data from December 2015 to November 2017. Prepared models were compared based on Akaike's information criterion, Bayesian information criterion and residual analysis. The selected model forecasted correctly with mean absolute errors of 0.07 and 0.22, and root mean squared errors of 0.09 and 0.28, for training and validation periods, respectively. There were no dengue epidemics observed in the district during the training period and nine outbreaks occurred during the forecasting period. The proposed model captured five outbreaks and correctly rejected 14 within the testing period of 24 months. The Pierce skill score of the model was 0.49, with a receiver operating characteristic of 86% and 92% sensitivity. The developed weather based forecasting model allows warnings of impending dengue outbreaks and epidemics in advance of one month with high accuracy. Depending upon climatic factors, the previous month's dengue cases had a significant effect on the dengue incidences of the current month. The simple, precise and understandable forecasting model developed could be used to manage limited public health resources effectively for patient management, vector surveillance and intervention programmes in the district.
Analysis of TLM Air-vent Model Applicability to EMC Problems for Normal Incident Plane Wave
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N. J. Nešić
2016-11-01
Full Text Available In this paper, the shielding properties related to a protective metal enclosure with airflow aperture arrays are numerically analyzed. As a numerical model, a TLM method, either in a conventional form based on fine mesh to describe apertures presence or enhanced with the compact air-vent model is employed. The main focus in the paper is on examining the limits of applying the compact air-vent model for EMC problems solving. Namely, various values for the distance between neighboring apertures in the TLM air-vent models as well as the air-vent thicknesses are analyzed. Specifically, the analyses are conducted for a normal incident plane wave, vertically and horizontally polarized.
Cawiding, Olive R.; Natividad, Gina May R.; Bato, Crisostomo V.; Addawe, Rizavel C.
2017-11-01
The prevalence of typhoid fever in developing countries such as the Philippines calls for a need for accurate forecasting of the disease. This will be of great assistance in strategic disease prevention. This paper presents a development of useful models that predict the behavior of typhoid fever incidence based on the monthly incidence in the provinces of the Cordillera Administrative Region from 2010 to 2015 using univariate time series analysis. The data used was obtained from the Cordillera Office of the Department of Health (DOH-CAR). Seasonal autoregressive moving average (SARIMA) models were used to incorporate the seasonality of the data. A comparison of the results of the obtained models revealed that the SARIMA (1,1,7)(0,0,1)12 with a fixed coefficient at the seventh lag produces the smallest root mean square error (RMSE), mean absolute error (MAE), Akaike Information Criterion (AIC), and Bayesian Information Criterion (BIC). The model suggested that for the year 2016, the number of cases would increase from the months of July to September and have a drop in December. This was then validated using the data collected from January 2016 to December 2016.
Baba, Isa Abdullahi; Hincal, Evren
2017-05-01
In this article we studied an epidemic model consisting of two strains with different types of incidence rates; bilinear and non-monotone. The model consists of four equilibrium points: disease-free equilibrium, endemic with respect to strain 1, endemic with respect to strain 2, and endemic with respect to both strains. The global stability analysis of the equilibrium points was carried out through the use of Lyapunov functions. Two basic reproduction ratios R 1 0 and R 2 0 are found, and we have shown that if both are less than one, the disease dies out, and if both are greater than one epidemic occurs. Furthermore, epidemics occur with respect to any strain with a basic reproduction ratio greater than one and disease dies out with respect to any strain with a basic reproduction ratio less than one. It was also shown that any strain with highest basic reproduction ratio will automatically outperform the other strain, thereby eliminating it. Numerical simulations were carried out to support the analytic result and to show the effect of the parameter k in the non-monotone incidence rate, which describes the psychological effect of general public towards infection.
Modeling Radar Scattering by Planetary Regoliths for Varying Angles of Incidence
Prem, P.; Patterson, G. W.; Zimmerman, M. I.
2017-12-01
Bistatic radar observations can play an important role in characterizing the texture and composition of planetary regoliths. Multiple scattering within a closely-packed particulate medium, such as a regolith, can lead to a response referred to as the Coherent Backscatter Opposition Effect (CBOE), associated with an increase in the intensity of backscattered radiation and an increase in Circular Polarization Ratio (CPR) at small bistatic angles. The nature of the CBOE is thought to depend not only on regolith properties, but also on the angle of incidence (Mishchenko, 1992). The latter factor is of particular interest in light of recent radar observations of the Moon over a range of bistatic and incidence angles by the Mini-RF instrument (on board the Lunar Reconnaissance Orbiter), operating in bistatic mode with a ground-based transmitter at the Arecibo Observatory. These observations have led to some intriguing results that are not yet well-understood - for instance, the lunar South Polar crater Cabeus shows an elevated CPR at only some combinations of incidence angle/bistatic angle, a potential clue to the depth distribution of water ice at the lunar poles (Patterson et al., 2017). Our objective in this work is to develop a model for radar scattering by planetary regoliths that can assist in the interpretation of Mini-RF observations. We approach the problem by coupling the Multiple Sphere T-Matrix (MSTM) code of Mackowski and Mishchenko (2011) to a Monte Carlo radiative transfer model. The MSTM code is based on the solution of Maxwell's equations for the propagation of electromagnetic waves in the presence of a cluster of scattering/absorbing spheres, and can be used to model the scattering of radar waves by an aggregation of nominal regolith particles. The scattering properties thus obtained serve as input to the Monte Carlo model, which is used to simulate radar scattering at larger spatial scales. The Monte Carlo approach has the advantage of being able to
Modelling psychological responses to the Great East Japan earthquake and nuclear incident.
Goodwin, Robin; Takahashi, Masahito; Sun, Shaojing; Gaines, Stanley O
2012-01-01
The Great East Japan (Tōhoku/Kanto) earthquake of March 2011 was followed by a major tsunami and nuclear incident. Several previous studies have suggested a number of psychological responses to such disasters. However, few previous studies have modelled individual differences in the risk perceptions of major events, or the implications of these perceptions for relevant behaviours. We conducted a survey specifically examining responses to the Great Japan earthquake and nuclear incident, with data collected 11-13 weeks following these events. 844 young respondents completed a questionnaire in three regions of Japan; Miyagi (close to the earthquake and leaking nuclear plants), Tokyo/Chiba (approximately 220 km from the nuclear plants), and Western Japan (Yamaguchi and Nagasaki, some 1000 km from the plants). Results indicated significant regional differences in risk perception, with greater concern over earthquake risks in Tokyo than in Miyagi or Western Japan. Structural equation analyses showed that shared normative concerns about earthquake and nuclear risks, conservation values, lack of trust in governmental advice about the nuclear hazard, and poor personal control over the nuclear incident were positively correlated with perceived earthquake and nuclear risks. These risk perceptions further predicted specific outcomes (e.g. modifying homes, avoiding going outside, contemplating leaving Japan). The strength and significance of these pathways varied by region. Mental health and practical implications of these findings are discussed in the light of the continuing uncertainties in Japan following the March 2011 events.
Modelling psychological responses to the Great East Japan earthquake and nuclear incident.
Directory of Open Access Journals (Sweden)
Robin Goodwin
Full Text Available The Great East Japan (Tōhoku/Kanto earthquake of March 2011 was followed by a major tsunami and nuclear incident. Several previous studies have suggested a number of psychological responses to such disasters. However, few previous studies have modelled individual differences in the risk perceptions of major events, or the implications of these perceptions for relevant behaviours. We conducted a survey specifically examining responses to the Great Japan earthquake and nuclear incident, with data collected 11-13 weeks following these events. 844 young respondents completed a questionnaire in three regions of Japan; Miyagi (close to the earthquake and leaking nuclear plants, Tokyo/Chiba (approximately 220 km from the nuclear plants, and Western Japan (Yamaguchi and Nagasaki, some 1000 km from the plants. Results indicated significant regional differences in risk perception, with greater concern over earthquake risks in Tokyo than in Miyagi or Western Japan. Structural equation analyses showed that shared normative concerns about earthquake and nuclear risks, conservation values, lack of trust in governmental advice about the nuclear hazard, and poor personal control over the nuclear incident were positively correlated with perceived earthquake and nuclear risks. These risk perceptions further predicted specific outcomes (e.g. modifying homes, avoiding going outside, contemplating leaving Japan. The strength and significance of these pathways varied by region. Mental health and practical implications of these findings are discussed in the light of the continuing uncertainties in Japan following the March 2011 events.
Renal function and incidence of chronic kidney disease in HIV patients
DEFF Research Database (Denmark)
Rasch, Magnus G.; Engsig, Frederik N; Feldt-Rasmussen, Bo
2012-01-01
Impaired renal function is of major concern in human immunodeficiency virus (HIV)-infected patients.......Impaired renal function is of major concern in human immunodeficiency virus (HIV)-infected patients....
Kidney Function, Proteinuria, and Cancer Incidence: The Korean Heart Study.
Mok, Yejin; Matsushita, Kunihiro; Ballew, Shoshana H; Sang, Yingying; Jung, Keum Ji; Lee, Sunmi; Jee, Sun Ha; Coresh, Josef
2017-10-01
Reported associations of estimated glomerular filtration rate (eGFR) with cancer risk are inconsistent, and data for the proteinuria-cancer relationship are sparse. We sought to quantify the associations of cancer incidence with eGFR and with proteinuria in a large population-based cohort. A prospective cohort study. 242,583 adults (30-74 years old) without a diagnosis of cancer at baseline in the Korean Heart Study, based on health checkups in 1996 to 2004 with follow-up until 2012. Creatinine-based eGFR (≥90, 60-89, 45-59, and cancer incidence based on ICD-10 codes. 15,165 cases of cancer were detected. The relationship between eGFR and incidence of any cancer was J shaped, with the lowest risk at 45 to 59mL/min/1.73m 2 . There was 44% higher risk for any cancer among those with eGFRscancer risk, showing a dose-response relationship (HRs of 1.24 [95% CI, 1.13-1.35], 1.38 [95% CI, 1.17-1.63], and 1.66 [95% CI, 1.30-2.12] for 1+, 2+, and ≥3+ vs undetectable/trace). Examining site-specific cancer, eGFRkidney and ureteral cancer, multiple myeloma, and leukemia, whereas proteinuria ≥ 1+ (vs undetectable/trace) was related to a broader set of cancers (ie, stomach, rectal, liver, lung, ovarian, kidney, bladder, and multiple myeloma). After excluding study participants with follow-up less than 3 years, the associations remained consistent for kidney cancer and myeloma with eGFR and for rectal, liver, lung, and ovarian cancer with proteinuria. Relatively small number of participants with severely reduced eGFR or 70 years or older. Kidney measures, particularly proteinuria, were associated with increased incidence of cancer. Future studies are needed to better understand the pathophysiologic mechanisms underlying these associations. Copyright © 2017 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.
Investigation of 234U(n,f) as a Function of Incident Neutron Energy
Al-Adili, A.; Hambsch, F.-J.; Oberstedt, S.; Pomp, S.
2011-10-01
Measurements of the reaction 234U(n,f) have been performed at incident neutron energies from 0.2 MeV to 5 MeV at the 7 MV Van De Graaf accelerator at IRMM. A twin Frisch-grid ionization chamber was used for fission-fragment detection. Parallel digital and analogue data acquisitions were applied in order to compare the two techniques. First results on the angular anisotropy and preliminary mass distributions are presented along with a first comparison between the two techniques.
Hydroclimatology of Dual-Peak Annual Cholera Incidence: Insights from a Spatially Explicit Model
Bertuzzo, E.; Mari, L.; Righetto, L.; Gatto, M.; Casagrandi, R.; Rodriguez-Iturbe, I.; Rinaldo, A.
2012-12-01
Cholera incidence in some regions of the Indian subcontinent may exhibit two annual peaks although the main environmental drivers that have been linked to the disease (e.g. sea surface temperature, zooplankton abundance, river discharge) peak once per year during the summer. An empirical hydroclimatological explanation relating cholera transmission to river flows and to the disease spatial spreading has been recently proposed. We specifically support and substantiate mechanistically such hypothesis by means of a spatially explicit model of cholera transmission. Our framework directly accounts for the role of the river network in transporting and redistributing cholera bacteria among human communities as well as for spatial and temporal annual fluctuations of precipitation and river flows. To single out the single out the hydroclimatologic controls on the prevalence patterns in a non-specific geographical context, we first apply the model to Optimal Channel Networks as a general model of hydrological networks. Moreover, we impose a uniform distribution of population. The model is forced by seasonal environmental drivers, namely precipitation, temperature and chlorophyll concentration in the coastal environment, a proxy for Vibrio cholerae concentration. Our results show that these drivers may suffice to generate dual-peak cholera prevalence patterns for proper combinations of timescales involved in pathogen transport, hydrologic variability and disease unfolding. The model explains the possible occurrence of spatial patterns of cholera incidence characterized by a spring peak confined to coastal areas and a fall peak involving inland regions. We then proceed applying the model to the specific settings of Bay of Bengal accounting for the actual river networks (derived from digital terrain map manipulations), the proper distribution of population (estimated from downscaling of census data based on remotely sensed features) and precipitation patterns. Overall our
Directory of Open Access Journals (Sweden)
Jin Cao
2017-01-01
Full Text Available Background: Hyperuricemia (HUA contributes to gout and many other diseases. Many hyperuricemia-related risk factors have been discovered, which provided the possibility for building the hyperuricemia prediction model. In this study we aimed to explore the incidence of hyperuricemia and develop hyperuricemia prediction models based on the routine biomarkers for both males and females in urban Han Chinese adults. Methods: A cohort of 58,542 members of the urban population (34,980 males and 23,562 females aged 20–80 years old, free of hyperuricemia at baseline examination, was followed up for a median 2.5 years. The Cox proportional hazards regression model was used to develop gender-specific prediction models. Harrell’s C-statistics was used to evaluate the discrimination ability of the models, and the 10-fold cross-validation was used to validate the models. Results: In 7139 subjects (5585 males and 1554 females, hyperuricemia occurred during a median of 2.5 years of follow-up, leading to a total incidence density of 49.63/1000 person years (64.62/1000 person years for males and 27.12/1000 person years for females. The predictors of hyperuricemia were age, body mass index (BMI systolic blood pressure, serum uric acid for males, and BMI, systolic blood pressure, serum uric acid, triglycerides for females. The models’ C statistics were 0.783 (95% confidence interval (CI, 0.779–0.786 for males and 0.784 (95% CI, 0.778–0.789 for females. After 10-fold cross-validation, the C statistics were still steady, with 0.782 for males and 0.783 for females. Conclusions: In this study, gender-specific prediction models for hyperuricemia for urban Han Chinese adults were developed and performed well.
Sáinz, M M; Toro, J C; Poblete, H B; Perez, L F; Nicovani, V H; Carrera, M G
2009-01-01
Delayed graft function (DGF) is defined as the need for dialysis within the first week after renal transplantation, and slow graft function as persistence of serum creatinine concentration of at least 3 mg/dL on day 5 after the procedure. In the present study, we analyzed the incidence and risk factors for DGF at our center. This retrospective study included 106 patients who underwent renal transplantation between January 2000 and June 2008. Of these, 11 patients were excluded. Two of the remaining 95 patients received organs from living donors, and 93 received cadaver organs. Variables analyzed included donor age, cause of death, cause of chronic renal failure, recipient age, method and time of long-term renal replacement therapy, residual diuresis, panel of reactive antibodies (PRA), HLA mismatch, sex compatibility, cold and warm ischemia times, biopsy-confirmed episodes of acute rejection, urine output in the operating room and in the first 24 hours after the procedure, and intraoperative induction therapy. Data were analyzed using the chi(2) and Fisher exact tests and analysis of variance, and are given as mean (SD) and frequency. Variables associated with DGF at univariate analysis (P < .05) were divided between risk factors and predictors of DGF for inclusion in logistic regression models. The incidence of DGF was 32.6%; slow graft function, 16.8%; and immediate graft function, 50.5%. Cold ischemia time longer than 20 hours (P = .02) and donor age (P = .008) were directly associated with DGF. Twenty-four-hour urine output was a strong predictor of DGF. Patients with DGF demonstrated a 25% incidence of an episode of acute rejection before discharge from the hospital. No difference in DGF was observed for use of intraoperative induction therapy.
Bertuzzo, E.; Mari, L.; Righetto, L.; Casagrandi, R.; Gatto, M.; Rodriguez-Iturbe, I.; Rinaldo, A.
2010-12-01
The seasonality of cholera and its relation with environmental drivers are receiving increasing interest and research efforts, yet they remain unsatisfactorily understood. A striking example is the observed annual cycle of cholera incidence in the Bengal region which exhibits two peaks despite the main environmental drivers that have been linked to the disease (air and sea surface temperature, zooplankton density, river discharge) follow a synchronous single-peak annual pattern. A first outbreak, mainly affecting the coastal regions, occurs in spring and it is followed, after a period of low incidence during summer, by a second, usually larger, peak in autumn also involving regions situated farther inland. A hydroclimatological explanation for this unique seasonal cycle has been recently proposed: the low river spring flows favor the intrusion of brackish water (the natural environment of the causative agent of the disease) which, in turn, triggers the first outbreak. The summer rising river discharges have a temporary dilution effect and prompt the repulsion of contaminated water which lowers the disease incidence. However, the monsoon flooding, together with the induced crowding of the population and the failure of the sanitation systems, can possibly facilitate the spatial transmission of the disease and promote the autumn outbreak. We test this hypothesis using a mechanistic, spatially explicit model of cholera epidemic. The framework directly accounts for the role of the river network in transporting and redistributing cholera bacteria among human communities as well as for the annual fluctuation of the river flow. The model is forced with the actual environmental drivers of the region, namely river flow and temperature. Our results show that these two drivers, both having a single peak in the summer, can generate a double peak cholera incidence pattern. Besides temporal patterns, the model is also able to qualitatively reproduce spatial patterns characterized
Aungaroon, Gewalin; Zea Vera, Alonso; Horn, Paul S; Byars, Anna W; Greiner, Hansel M; Tenney, Jeffrey R; Arthur, Todd M; Crone, Nathan E; Holland, Katherine D; Mangano, Francesco T; Arya, Ravindra
2017-10-01
This study examined the incidence, thresholds, and determinants of electrical cortical stimulation (ECS)-induced after-discharges (ADs) and seizures. Electrocorticograph recordings were reviewed to determine incidence of ECS-induced ADs and seizures. Multivariable analyses for predictors of AD/seizure occurrence and their thresholds were performed. In 122 patients, the incidence of ADs and seizures was 77% (94/122) and 35% (43/122) respectively. Males (odds ratio [OR] 2.92, 95% CI 1.21-7.38, p=0.02) and MRI-negative patients (OR 3.69, 95% CI 1.24-13.7, p=0.03) were found to have higher odds of ECS-induced ADs. A significant trend for decreasing AD thresholds with age was seen (regression co-efficient -0.151, 95% CI -0.267 to -0.035, p=0.011). ECS-induced seizures were more likely in patients with lateralized functional imaging (OR 6.62, 95% CI 1.36-55.56, p=0.036, for positron emission tomography) and presence of ADs (OR 3.50, 95% CI 1.12-13.36, p=0.043). ECS is associated with a high incidence of ADs and seizures. With age, current thresholds decrease and the probability for AD/seizure occurrence increases. ADs and seizures during ECS brain mapping are potentially hazardous and affect its functional validity. Thus, safer method(s) for brain mapping with improved neurophysiologic validity are desirable. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.
The interaction evolution model of mass incidents with delay in a social network
Huo, Liang'an; Ma, Chenyang
2017-10-01
Recent years have witnessed rapid development of information technology. Today, modern media is widely used for the purpose of spreading information rapidly and widely. In particular, through micro-blog promotions, individuals tend to express their viewpoints and spread information on the internet, which could easily lead to public opinions. Moreover, government authorities also disseminate official information to guide public opinion and eliminate any incorrect conjecture. In this paper, a dynamical model with two delays is investigated to exhibit the interaction evolution between the public and official opinion fields in network mass incidents. Based on the theory of differential equations, the interaction mechanism between two public opinion fields in a micro-blog environment is analyzed. Two delays are proposed in the model to depict the response delays of public and official opinion fields. Some stable conditions are obtained, which shows that Hopf bifurcation can occur as delays cross critical values. Further, some numerical simulations are carried out to verify theoretical results. Our model indicates that there exists a golden time for government intervention, which should be emphasized given the impact of modern media and inaccurate rumors. If the government releases official information during the golden time, mass incidents on the internet can be controlled effectively.
Chaos induced by breakup of waves in a spatial epidemic model with nonlinear incidence rate
International Nuclear Information System (INIS)
Sun, Gui-Quan; Jin, Zhen; Liu, Quan-Xing; Li, Li
2008-01-01
Spatial epidemiology is the study of spatial variation in disease risk or incidence, including the spatial patterns of the population. The spread of diseases in human populations can exhibit large scale patterns, underlining the need for spatially explicit approaches. In this paper, the spatiotemporal complexity of a spatial epidemic model with nonlinear incidence rate, which includes the behavioral changes and crowding effect of the infective individuals, is investigated. Based on both theoretical analysis and computer simulations, we find out when, under the parameters which can guarantee a stable limit cycle in the non-spatial model, spiral and target waves can emerge. Moreover, two different kinds of breakup of waves are shown. Specifically, the breakup of spiral waves is from the core and the breakup of target waves is from the far-field, and both kinds of waves become irregular patterns at last. Our results reveal that the spatiotemporal chaos is induced by the breakup of waves. The results obtained confirm that diffusion can form spiral waves, target waves or spatial chaos of high population density, which enrich the findings of spatiotemporal dynamics in the epidemic model
Computational Modelling and Optimal Control of Ebola Virus Disease with non-Linear Incidence Rate
Takaidza, I.; Makinde, O. D.; Okosun, O. K.
2017-03-01
The 2014 Ebola outbreak in West Africa has exposed the need to connect modellers and those with relevant data as pivotal to better understanding of how the disease spreads and quantifying the effects of possible interventions. In this paper, we model and analyse the Ebola virus disease with non-linear incidence rate. The epidemic model created is used to describe how the Ebola virus could potentially evolve in a population. We perform an uncertainty analysis of the basic reproductive number R 0 to quantify its sensitivity to other disease-related parameters. We also analyse the sensitivity of the final epidemic size to the time control interventions (education, vaccination, quarantine and safe handling) and provide the cost effective combination of the interventions.
Track etching model for normal incident heavy ion recording in isotropic dielectric detectors
International Nuclear Information System (INIS)
Membrey, F.; Chambaudet, A.; Fromm, M.; Saouli, R.
1990-01-01
Heavy ion recording in dielectric isotropic detectors has a wide range of applications in such areas as uranium cartography, neutron activation and fission track dating using the external detector method (EDM). It is important to have a good understanding of etch pit evolution during chemical etching. The conical model, which is very often used, is based on a constant track etching velocity (VT). Numerous experiments have shown, however, that VT varies along the damage trail. In this paper, we propose a computer-generated model which simulates the etching process for normal incident ions. The analytical form of VT must be chosen in order to describe as precisely as possible the relationship between etching time (residual range) and the VT value. The conical model only provides a primary approximation which is generally insufficient, especially when performing cartography. (author)
Chang, Yaojen; Schechter, Clyde B; van Ravesteyn, Nicolien T; Near, Aimee M; Heijnsdijk, Eveline A M; Adams-Campbell, Lucile; Levy, David; de Koning, Harry J; Mandelblatt, Jeanne S
2012-12-01
Obesity affects multiple points along the breast cancer control continuum from prevention to screening and treatment, often in opposing directions. Obesity is also more prevalent in Blacks than Whites at most ages so it might contribute to observed racial disparities in mortality. We use two established simulation models from the Cancer Intervention and Surveillance Modeling Network (CISNET) to evaluate the impact of obesity on race-specific breast cancer outcomes. The models use common national data to inform parameters for the multiple US birth cohorts of Black and White women, including age- and race-specific incidence, competing mortality, mammography characteristics, and treatment effectiveness. Parameters are modified by obesity (BMI of ≥ 30 kg/m(2)) in conjunction with its age-, race-, cohort- and time-period-specific prevalence. We measure age-standardized breast cancer incidence and mortality and cases and deaths attributable to obesity. Obesity is more prevalent among Blacks than Whites until age 74; after age 74 it is more prevalent in Whites. The models estimate that the fraction of the US breast cancer cases attributable to obesity is 3.9-4.5 % (range across models) for Whites and 2.5-3.6 % for Blacks. Given the protective effects of obesity on risk among women obesity in this age group could increase cases for both the races, but decrease cases for women ≥ 50 years. Overall, obesity accounts for 4.4-9.2 % and 3.1-8.4 % of the total number of breast cancer deaths in Whites and Blacks, respectively, across models. However, variations in obesity prevalence have no net effect on race disparities in breast cancer mortality because of the opposing effects of age on risk and patterns of age- and race-specific prevalence. Despite its modest impact on breast cancer control and race disparities, obesity remains one of the few known modifiable risks for cancer and other diseases, underlining its relevance as a public health target.
Dai, Yunxian; Lin, Yiping; Zhao, Huitao; Khalique, Chaudry Masood
2016-06-01
In this paper, a delayed computer virus propagation model with a saturation incidence rate and a time delay describing temporary immune period is proposed and its dynamical behaviors are studied. The threshold value ℜ0 is given to determine whether the virus dies out completely. By comparison arguments and iteration technique, sufficient conditions are obtained for the global asymptotic stabilities of the virus-free equilibrium and the virus equilibrium. Taking the delay as a parameter, local Hopf bifurcations are demonstrated. Furthermore, the direction of Hopf bifurcation and the stabilities of the bifurcating periodic solutions are determined by the normal form theory and the center manifold theorem for functional differential equations (FDEs). Finally, numerical simulations are carried out to illustrate the main theoretical results.
[Apnoea in infants with bronchiolitis: Incidence and risk factors for a prediction model].
Ramos-Fernández, José Miguel; Moreno-Pérez, David; Gutiérrez-Bedmar, Mario; Ramírez-Álvarez, María; Martínez García, Yasmina; Artacho-González, Lourdes; Urda-Cardona, Antonio
2017-05-04
The presence of apnoea in acute bronchiolitis (AB) varies between 1.2% and 28.8%, depending on the series, and is one of its most fearsome complications. The aim of this study is to determine the incidence of apnoea in hospitalised patients diagnosed with AB, and to define their associated risk factors in order to construct a prediction model. A retrospective observational study of patients admitted to a tertiary hospital in the last 5 years with a diagnosis of AB, according to the classic criteria. Data was collected on the frequency of apnoea and related clinical variables to find risk factors in a binary logistic regression model for the prediction of apnoea. A ROC curve was developed with the model. Apnoea was recorded during the admission of 53 (4.4%) patients out of a total 1,197 cases found. The risk factors included in the equation were: Female (OR 0.6, 95% CI: 0.27-1.37), Caesarean delivery (OR: 3.44, 95% CI: 1.5-7.7), Postmenstrual age ≤43 weeks (OR: 6.62, 95% CI: 2.38-18.7), Fever (OR: 0.33, 95% CI: 0.09-1.97), Low birth weight (OR: 5.93, 95% CI: 2.23-7.67), Apnoea observed by caregivers before admission (OR: 5.93, 95% CI: 2.64-13.3), and severe bacterial infection (OR: 3.98, 95% CI: 1.68-9.46). The optimal sensitivity and specificity of the model in the ROC curve was 0.842 and 0.846, respectively (P<.001). The incidence of apnoea during admission was 4.4 per 100 admissions of AB and year. The estimated prediction model equation may be of help to the clinician in order to classify patients with increased risk of apnoea during admission due to AB. Copyright © 2017. Publicado por Elsevier España, S.L.U.
The Swiss cheese model of safety incidents: are there holes in the metaphor?
Directory of Open Access Journals (Sweden)
Perneger Thomas V
2005-11-01
Full Text Available Abstract Background Reason's Swiss cheese model has become the dominant paradigm for analysing medical errors and patient safety incidents. The aim of this study was to determine if the components of the model are understood in the same way by quality and safety professionals. Methods Survey of a volunteer sample of persons who claimed familiarity with the model, recruited at a conference on quality in health care, and on the internet through quality-related websites. The questionnaire proposed several interpretations of components of the Swiss cheese model: a slice of cheese, b hole, c arrow, d active error, e how to make the system safer. Eleven interpretations were compatible with this author's interpretation of the model, 12 were not. Results Eighty five respondents stated that they were very or quite familiar with the model. They gave on average 15.3 (SD 2.3, range 10 to 21 "correct" answers out of 23 (66.5% – significantly more than 11.5 "correct" answers that would expected by chance (p Conclusion The interpretations of specific features of the Swiss cheese model varied considerably among quality and safety professionals. Reaching consensus about concepts of patient safety requires further work.
The hospital incident command system: modified model for hospitals in iran.
Djalali, Ahmadreza; Hosseinijenab, Vahid; Peyravi, Mahmoudreza; Nekoei-Moghadam, Mahmood; Hosseini, Bashir; Schoenthal, Lisa; Koenig, Kristi L
2015-03-27
Effectiveness of hospital management of disasters requires a well-defined and rehearsed system. The Hospital Incident Command System (HICS), as a standardized method for command and control, was established in Iranian hospitals, but it has performed fairly during disaster exercises. This paper describes the process for, and modifications to HICS undertaken to optimize disaster management in hospitals in Iran. In 2013, a group of 11 subject matter experts participated in an expert consensus modified Delphi to develop modifications to the 2006 version of HICS. The following changes were recommended by the expert panel and subsequently implemented: 1) A Quality Control Officer was added to the Command group; 2) Security was defined as a new section; 3) Infrastructure and Business Continuity Branches were moved from the Operations Section to the Logistics and the Administration Sections, respectively; and 4) the Planning Section was merged within the Finance/Administration Section. An expert consensus group developed a modified HICS that is more feasible to implement given the managerial organization of hospitals in Iran. This new model may enhance hospital performance in managing disasters. Additional studies are needed to test the feasibility and efficacy of the modified HICS in Iran, both during simulations and actual disasters. This process may be a useful model for other countries desiring to improve disaster incident management systems for their hospitals.
Barrios, J. M.; Verstraeten, W. W.; Farifteh, J.; Maes, P.; Aerts, J. M.; Coppin, P.
2012-04-01
Lyme borreliosis (LB) is the most common tick-borne disease in Europe and incidence growth has been reported in several European countries during the last decade. LB is caused by the bacterium Borrelia burgdorferi and the main vector of this pathogen in Europe is the tick Ixodes ricinus. LB incidence and spatial spread is greatly dependent on environmental conditions impacting habitat, demography and trophic interactions of ticks and the wide range of organisms ticks parasite. The landscape configuration is also a major determinant of tick habitat conditions and -very important- of the fashion and intensity of human interaction with vegetated areas, i.e. human exposure to the pathogen. Hence, spatial notions as distance and adjacency between urban and vegetated environments are related to human exposure to tick bites and, thus, to risk. This work tested the adequacy of a gravity model setting to model the observed spatio-temporal pattern of LB as a function of location and size of urban and vegetated areas and the seasonal and annual change in the vegetation dynamics as expressed by MODIS NDVI. Opting for this approach implies an analogy with Newton's law of universal gravitation in which the attraction forces between two bodies are directly proportional to the bodies mass and inversely proportional to distance. Similar implementations have proven useful in fields like trade modeling, health care service planning, disease mapping among other. In our implementation, the size of human settlements and vegetated systems and the distance separating these landscape elements are considered the 'bodies'; and the 'attraction' between them is an indicator of exposure to pathogen. A novel element of this implementation is the incorporation of NDVI to account for the seasonal and annual variation in risk. The importance of incorporating this indicator of vegetation activity resides in the fact that alterations of LB incidence pattern observed the last decade have been ascribed
Vilà de Muga, M; Serrano Llop, A; Rifé Escudero, E; Jabalera Contreras, M; Luaces Cubells, C
2015-10-01
The aim of this study is to analyse changes in the incidents reported after the implementation of a new model, and study its results on patient safety. In 2012 an observational study with prospective collection of incidents reported between 2007 and 2011 was conducted. In May 2012 a model change was made in order to increase the number of reports, analyse their causes, and improve the feedback to the service. Professional safety representatives were assigned to every department, information and diffusion sessions were held, and a new incident reporting system was implemented. With the new model, a new observational study with prospective collection of the reports during one year was initiated, and the results compared between models. In 2011, only 19 incidents were reported in the Emergency Department, and between June 1, 2012 to June 1, 2013, 106 incidents (5.6 times more). The incidents reported were medication incidents (57%), identification (26%), and procedures (7%). The most frequent causes were human (70.7%), lack of training (22.6%), and working conditions (15.1%). Some measures were implemented as a result of these incidents: a surgical checklist, unit doses of salbutamol, tables of weight-standardised doses of drugs for cardiopulmonary resuscitation. The new model of reporting incidents has enhanced the reports and has allowed improvements and the implementation of preventive measures, increasing the patient safety in the Emergency Department. Copyright © 2014 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.
Response Surface Modeling Using Multivariate Orthogonal Functions
Morelli, Eugene A.; DeLoach, Richard
2001-01-01
A nonlinear modeling technique was used to characterize response surfaces for non-dimensional longitudinal aerodynamic force and moment coefficients, based on wind tunnel data from a commercial jet transport model. Data were collected using two experimental procedures - one based on modem design of experiments (MDOE), and one using a classical one factor at a time (OFAT) approach. The nonlinear modeling technique used multivariate orthogonal functions generated from the independent variable data as modeling functions in a least squares context to characterize the response surfaces. Model terms were selected automatically using a prediction error metric. Prediction error bounds computed from the modeling data alone were found to be- a good measure of actual prediction error for prediction points within the inference space. Root-mean-square model fit error and prediction error were less than 4 percent of the mean response value in all cases. Efficacy and prediction performance of the response surface models identified from both MDOE and OFAT experiments were investigated.
Functional Modeling of Neural-Glia Interaction
DEFF Research Database (Denmark)
Postnov, D.E.; Brazhe, N.A.; Sosnovtseva, Olga
2012-01-01
Functional modeling is an approach that focuses on the representation of the qualitative dynamics of the individual components (e.g. cells) of a system and on the structure of the interaction network.......Functional modeling is an approach that focuses on the representation of the qualitative dynamics of the individual components (e.g. cells) of a system and on the structure of the interaction network....
Neural modeling of prefrontal executive function
Energy Technology Data Exchange (ETDEWEB)
Levine, D.S. [Univ. of Texas, Arlington, TX (United States)
1996-12-31
Brain executive function is based in a distributed system whereby prefrontal cortex is interconnected with other cortical. and subcortical loci. Executive function is divided roughly into three interacting parts: affective guidance of responses; linkage among working memory representations; and forming complex behavioral schemata. Neural network models of each of these parts are reviewed and fit into a preliminary theoretical framework.
Kondo, Naoki; Suzuki, Kohta; Minai, Junko; Yamagata, Zentaro
2012-01-01
Rotating savings and credit associations (ROSCAs) involve group financial self-help activities. These voluntary financial cooperative associations-mujin in Japanese-are found in some rural areas of Japan. Cross-sectional evidence suggests that active participation in mujin correlates with rich social capital and better functional capacities among older adults. However, the effect of mujin on subsequent health outcomes is unknown. In 2003, we conducted a baseline interview survey of 583 functionally independent adults randomly selected from Yamanashi Prefecture residents aged 65 years or older. They were followed up until 2011. We used proportional hazards models, and factor analysis of 8 mujin-related questions identified 2 components: the "intensity and attitude" and "financing" aspects of mujin. The hazard ratios (HRs) for incident functional disability-identified by using the public long-term care insurance database-per 1-SD increase in factor scores were 0.82 (95% CI: 0.68-0.99) for the intensity and attitude score and 1.21 (1.07-1.38) for financing score. Adjustments for age, sex, marital status, household composition, physical health, education, income, and other factor scores only slightly attenuated these HRs. The results for mortality models were very similar to those for incident functional disability. ROSCA-type activities in Japan could have beneficial effects on the health of older adults if used primarily for the purpose of friendship. Mujin for aggressively financial purposes might be somewhat harmful, as such activities might reflect the "dark side" of social capital, ie, overly demanding expectations of group conformity.
A Multivariate Approach to Functional Neuro Modeling
DEFF Research Database (Denmark)
Mørch, Niels J.S.
1998-01-01
by the application of linear and more flexible, nonlinear microscopic regression models to a real-world dataset. The dependency of model performance, as quantified by generalization error, on model flexibility and training set size is demonstrated, leading to the important realization that no uniformly optimal model......, provides the basis for a generalization theoretical framework relating model performance to model complexity and dataset size. Briefly summarized the major topics discussed in the thesis include: - An introduction of the representation of functional datasets by pairs of neuronal activity patterns...... exists. - Model visualization and interpretation techniques. The simplicity of this task for linear models contrasts the difficulties involved when dealing with nonlinear models. Finally, a visualization technique for nonlinear models is proposed. A single observation emerges from the thesis...
Brouwer, Andrew F; Meza, Rafael; Eisenberg, Marisa C
2017-03-01
Many cancers are understood to be the product of multiple somatic mutations or other rate-limiting events. Multistage clonal expansion (MSCE) models are a class of continuous-time Markov chain models that capture the multi-hit initiation-promotion-malignant-conversion hypothesis of carcinogenesis. These models have been used broadly to investigate the epidemiology of many cancers, assess the impact of carcinogen exposures on cancer risk, and evaluate the potential impact of cancer prevention and control strategies on cancer rates. Structural identifiability (the analysis of the maximum parametric information available for a model given perfectly measured data) of certain MSCE models has been previously investigated. However, structural identifiability is a theoretical property and does not address the limitations of real data. In this study, we use pancreatic cancer as a case study to examine the practical identifiability of the two-, three-, and four-stage clonal expansion models given age-specific cancer incidence data using a numerical profile-likelihood approach. We demonstrate that, in the case of the three- and four-stage models, several parameters that are theoretically structurally identifiable, are, in practice, unidentifiable. This result means that key parameters such as the intermediate cell mutation rates are not individually identifiable from the data and that estimation of those parameters, even if structurally identifiable, will not be stable. We also show that products of these practically unidentifiable parameters are practically identifiable, and, based on this, we propose new reparameterizations of the model hazards that resolve the parameter estimation problems. Our results highlight the importance of identifiability to the interpretation of model parameter estimates.
Forecasting the Incidence of Mumps in Zibo City Based on a SARIMA Model.
Xu, Qinqin; Li, Runzi; Liu, Yafei; Luo, Cheng; Xu, Aiqiang; Xue, Fuzhong; Xu, Qing; Li, Xiujun
2017-08-17
This study aimed to predict the incidence of mumps using a seasonal autoregressive integrated moving average (SARIMA) model, and provide theoretical evidence for early warning prevention and control in Zibo City, Shandong Province, China. Monthly mumps data from Zibo City gathered between 2005 and 2013 were used as a training set to construct a SARIMA model, and the monthly mumps in 2014 were defined as a test set for the model. From 2005 to 2014, a total of 8722 cases of mumps were reported in Zibo City; the male-to-female ratio of cases was 1.85:1, the age group of 1-20 years old accounted for 94.05% of all reported cases, and students made up the largest proportion (65.89%). The main serious endemic areas of mumps were located in Huantai County, Linzi District, and Boshan District of Zibo City. There were two epidemic peaks from April to July and from October to January in next year. The fitted model SARIMA (0, 1, 1) (0, 1, 1) 12 was established (AIC = 157.528), which has high validity and reasonability. The SARIMA model fitted dynamic changes of mumps in Zibo City well. It can be used for short-term forecasting and early warning of mumps.
Executive function, but not memory, associates with incident coronary heart disease and stroke
DEFF Research Database (Denmark)
Rostamian, Somayeh; van Buchem, Mark A; Westendorp, Rudi G J
2015-01-01
from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER) with Mini-Mental State Examination score ≥24 points. Scores on the Stroop Color-Word Test (selective attention) and the Letter Digit Substitution Test (processing speed) were converted to Z scores and averaged into a composite.......57-1.32). CONCLUSION: Lower executive function, but not memory, is associated with higher risk of coronary heart disease and stroke. Lower executive function, as an independent risk indicator, might better reflect brain vascular pathologies....
Based on Agent Model and K-Core Decomposition to Analyze the Diffusion of Mass Incident in Microblog
Directory of Open Access Journals (Sweden)
Jun Pan
2017-01-01
Full Text Available Mass incidents, which may influence the stability and security of the society in China, are getting more and more attentions not only from policy makers but also from Chinese social researchers. Catching the diffusion mechanism is believed to be critical to understand essential of these mass incidents since message dissemination plays important roles in every stage of mass incident. Recently, online social networks including Weibo (Chinese Twitter become more and more popular in China. There are reports showing that Weibo discussion has accompanied the processes of most mass incidents happening in China in these few years. So, in this paper, we aim at introducing K-Core decomposition method from complex network to the analysis on how to manage the diffusion of mass incident in Weibo based on agent based model which can simulate Weibo user’s actions when mass incident happens. This work can help people understand how mass incident messages spread across the network. And then, people may have better strategy to manage the diffusion of mass incidents.
Rosano, Caterina; Newman, Anne B; Katz, Ronit; Hirsch, Calvin H; Kuller, Lewis H
2008-09-01
To determine whether, in well-functioning older adults, a lower score on the Digit Symbol Substitution Test (DSST) and slower gait are associated with greater risk of mortality and of developing incident disability independent of other risk factors, including brain structural abnormalities (white matter hyperintensities, brain infarcts, ventricular enlargement) and whether the combination of varying levels of DSST score and gait speed are associated with a greater risk of mortality and disability than low DSST or slow gait alone. Observational cohort study. Community. Three thousand one hundred fifty-six (43% men, 29% black, mean age 70.4) participants in the Cardiovascular Health Study (CHS), free from stroke and physical disability and with a modified Mini-Mental State Examination (3MS) score of 80 or higher. Total mortality and incident disability (self-report of any difficulty performing one or more of the six activities of daily living) ascertained over a median follow-up time of 8.4 years. By the end of follow-up, 704 participants had died and 1,096 had incident disability. In Cox proportional hazards models adjusted for age, sex, race, education, cardiovascular disease, and brain magnetic resonance imaging abnormalities, lower DSST score and slower gait remained significantly associated with greater risk of mortality and of incident disability. Mortality rates were higher in those who had both low DSST score (<27 points) and slow gait (speed <1.0 m/s) than in those who had only low DSST score, only slow gait, or neither (rates per 1,000 person years (p-y): 61.2, 42.8, 20.8, and 16.3, respectively). A similar risk gradient was observed for incident disability (82.0, 57.9, 47.9, and 36.0/1,000 p-y, respectively). In well-functioning older adults, low DSST score and slow gait, alone or in combination, could be risk factors for mortality and for developing disability, independent of other risk factors, including measures of brain integrity.
Prediction of Chemical Function: Model Development and ...
The United States Environmental Protection Agency’s Exposure Forecaster (ExpoCast) project is developing both statistical and mechanism-based computational models for predicting exposures to thousands of chemicals, including those in consumer products. The high-throughput (HT) screening-level exposures developed under ExpoCast can be combined with HT screening (HTS) bioactivity data for the risk-based prioritization of chemicals for further evaluation. The functional role (e.g. solvent, plasticizer, fragrance) that a chemical performs can drive both the types of products in which it is found and the concentration in which it is present and therefore impacting exposure potential. However, critical chemical use information (including functional role) is lacking for the majority of commercial chemicals for which exposure estimates are needed. A suite of machine-learning based models for classifying chemicals in terms of their likely functional roles in products based on structure were developed. This effort required collection, curation, and harmonization of publically-available data sources of chemical functional use information from government and industry bodies. Physicochemical and structure descriptor data were generated for chemicals with function data. Machine-learning classifier models for function were then built in a cross-validated manner from the descriptor/function data using the method of random forests. The models were applied to: 1) predict chemi
Thirring model partition functions and harmonic differentials
Freedman, D. Z.; Pilch, K.
1988-10-01
The partition function of the Thirring model on a Riemann surface is calculated using the representation of the model as a fermion interacting with an auxiliary vector potential. The Hodge decomposition of the potential is used and the integral over the harmonic forms is shown to reproduce exactly the soliton sum in the bosonic version of the theory.
The NJL Model for Quark Fragmentation Functions
Energy Technology Data Exchange (ETDEWEB)
T. Ito, W. Bentz, I. Cloet, A W Thomas, K. Yazaki
2009-10-01
A description of fragmentation functions which satisfy the momentum and isospin sum rules is presented in an effective quark theory. Concentrating on the pion fragmentation function, we first explain the reason why the elementary (lowest order) fragmentation process q → qπ is completely inadequate to describe the empirical data, although the “crossed” process π → qq describes the quark distribution functions in the pion reasonably well. Then, taking into account cascade-like processes in a modified jet-model approach, we show that the momentum and isospin sum rules can be satisfied naturally without introducing any ad-hoc parameters. We present numerical results for the Nambu-Jona-Lasinio model in the invariant mass regularization scheme, and compare the results with the empirical parametrizations. We argue that this NJL-jet model provides a very useful framework to calculate the fragmentation functions in an effective chiral quark theory.
Structure functions in the chiral bag model
Energy Technology Data Exchange (ETDEWEB)
Sanjose, V.; Vento, V.
1989-07-13
We calculate the structure functions of an isoscalar nuclear target for the deep inelastic scattering by leptons in an extended version of the chiral bag model which incorporates the qanti q structure of the pions in the cloud. Bjorken scaling and Regge behavior are satisfied. The model calculation reproduces the low-x behavior of the data but fails to explain the medium- to large-x behavior. Evolution of the quark structure functions seem inevitable to attempt a connection between the low-energy models and the high-energy behavior of quantum chromodynamics. (orig.).
Circumplex model of family function in practice.
Furst, A L
1983-08-01
The recent dramatic resurgence in Israel of family medicine as a medical specialty has stimulated interest in concepts that view family function and dysfunction from the standpoint of family relationships and interaction, and in which the family is seen as a unit rather than as a collection of individuals. One model of family functioning, the circumplex model, is explained. This is based upon two dimensions, cohesion and adaptability. The potential relevance of this model to family medicine in Israel is discussed, along with a brief account of the author's initial steps in developing it for use as a tool in practice.
Lordan, Sinéad; Ross, R. Paul; Stanton, Catherine
2011-01-01
The marine environment represents a relatively untapped source of functional ingredients that can be applied to various aspects of food processing, storage, and fortification. Moreover, numerous marine-based compounds have been identified as having diverse biological activities, with some reported to interfere with the pathogenesis of diseases. Bioactive peptides isolated from fish protein hydrolysates as well as algal fucans, galactans and alginates have been shown to possess anticoagulant, anticancer and hypocholesterolemic activities. Additionally, fish oils and marine bacteria are excellent sources of omega-3 fatty acids, while crustaceans and seaweeds contain powerful antioxidants such as carotenoids and phenolic compounds. On the basis of their bioactive properties, this review focuses on the potential use of marine-derived compounds as functional food ingredients for health maintenance and the prevention of chronic diseases. PMID:21747748
Directory of Open Access Journals (Sweden)
Catherine Stanton
2011-06-01
Full Text Available The marine environment represents a relatively untapped source of functional ingredients that can be applied to various aspects of food processing, storage, and fortification. Moreover, numerous marine-based compounds have been identified as having diverse biological activities, with some reported to interfere with the pathogenesis of diseases. Bioactive peptides isolated from fish protein hydrolysates as well as algal fucans, galactans and alginates have been shown to possess anticoagulant, anticancer and hypocholesterolemic activities. Additionally, fish oils and marine bacteria are excellent sources of omega-3 fatty acids, while crustaceans and seaweeds contain powerful antioxidants such as carotenoids and phenolic compounds. On the basis of their bioactive properties, this review focuses on the potential use of marine-derived compounds as functional food ingredients for health maintenance and the prevention of chronic diseases.
Clinical-genetic model predicts incident impulse control disorders in Parkinson’s disease
Kraemmer, Julia; Smith, Kara; Weintraub, Daniel; Guillemot, Vincent; Nalls, Mike A; Cormier-Dequaire, Florence; Moszer, Ivan; Brice, Alexis; Singleton, Andrew B; Corvol, Jean-Christophe
2016-01-01
Objectives Impulse control disorders (ICD) are commonly associated with dopamine replacement therapy (DRT) in patients with Parkinson’s disease (PD). Our aims were to estimate ICD heritability and to predict ICD by a candidate genetic multivariable panel in patients with PD. Methods Data from de novo patients with PD, drug-naïve and free of ICD behaviour at baseline, were obtained from the Parkinson’s Progression Markers Initiative cohort. Incident ICD behaviour was defined as positive score on the Questionnaire for Impulsive-Compulsive Disorders in PD. ICD heritability was estimated by restricted maximum likelihood analysis on whole exome sequencing data. 13 candidate variants were selected from the DRD2, DRD3, DAT1, COMT, DDC, GRIN2B, ADRA2C, SERT, TPH2, HTR2A, OPRK1 and OPRM1 genes. ICD prediction was evaluated by the area under the curve (AUC) of receiver operating characteristic (ROC) curves. Results Among 276 patients with PD included in the analysis, 86% started DRT, 40% were on dopamine agonists (DA), 19% reported incident ICD behaviour during follow-up. We found heritability of this symptom to be 57%. Adding genotypes from the 13 candidate variants significantly increased ICD predictability (AUC=76%, 95% CI (70% to 83%)) compared to prediction based on clinical variables only (AUC=65%, 95% CI (58% to 73%), p=0.002). The clinical-genetic prediction model reached highest accuracy in patients initiating DA therapy (AUC=87%, 95% CI (80% to 93%)). OPRK1, HTR2A and DDC genotypes were the strongest genetic predictive factors. Conclusions Our results show that adding a candidate genetic panel increases ICD predictability, suggesting potential for developing clinical-genetic models to identify patients with PD at increased risk of ICD development and guide DRT management. PMID:27076492
Wannamethee, S Goya; Shaper, A Gerald; Papacosta, Olia; Lennon, Lucy; Welsh, Paul; Whincup, Peter H
2016-06-01
The association between lung function and cardiac markers and heart failure (HF) has been little studied in the general older population. We have examined the association between lung function and airway obstruction with cardiac markers N-terminal pro-brain natriuretic peptide (NT-proBNP) and cardiac troponin T (cTnT) and risk of incident HF in older men. Prospective study of 3242 men aged 60-79 years without prevalent HF or myocardial infarction followed up for an average period of 13 years, in whom 211 incident HF cases occurred. Incident HF was examined in relation to % predicted FEV1 and FVC. The Global Initiative on Obstructive Lung Diseases spirometry criteria were used to define airway obstruction. Reduced FEV1, but not FVC in the normal range, was significantly associated with increased risk of HF after adjustment for established HF risk factors including inflammation. The adjusted HRs comparing men in the 6-24th percentile with the highest quartile were 1.91 (1.24 to 2.94) and 1.30 (0.86 to 1.96) for FEV1 and FVC, respectively. FEV1 and FVC were inversely associated with NT-proBNP and cTnT, although the association between FEV1 and incident HF remained after adjustment for NT-proBNP and cTnT. Compared with normal subjects (FEV1/FVC ≥0.70 and FVC≥80%), moderate or severe (FEV1/FVC <0.70 and FEV1 <80%) airflow obstruction was independently associated with HF ((adjusted relative risk 1.59 (1.08 to 2.33)). Airflow restriction (FEV1/FVC ≥0.70 and FVC <80%) was not independently associated with HF. Reduced FEV1 reflecting airflow obstruction is associated with cardiac dysfunction and increased risk of incident HF in older men. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/
Liu, L; Luan, R S; Yin, F; Zhu, X P; Lü, Q
2016-01-01
Hand, foot and mouth disease (HFMD) is an infectious disease caused by enteroviruses, which usually occurs in children aged <5 years. In China, the HFMD situation is worsening, with increasing number of cases nationwide. Therefore, monitoring and predicting HFMD incidence are urgently needed to make control measures more effective. In this study, we applied an autoregressive integrated moving average (ARIMA) model to forecast HFMD incidence in Sichuan province, China. HFMD infection data from January 2010 to June 2014 were used to fit the ARIMA model. The coefficient of determination (R 2), normalized Bayesian Information Criterion (BIC) and mean absolute percentage of error (MAPE) were used to evaluate the goodness-of-fit of the constructed models. The fitted ARIMA model was applied to forecast the incidence of HMFD from April to June 2014. The goodness-of-fit test generated the optimum general multiplicative seasonal ARIMA (1,0,1) × (0,1,0)12 model (R 2 = 0·692, MAPE = 15·982, BIC = 5·265), which also showed non-significant autocorrelations in the residuals of the model (P = 0·893). The forecast incidence values of the ARIMA (1,0,1) × (0,1,0)12 model from July to December 2014 were 4103-9987, which were proximate forecasts. The ARIMA model could be applied to forecast HMFD incidence trend and provide support for HMFD prevention and control. Further observations should be carried out continually into the time sequence, and the parameters of the models could be adjusted because HMFD incidence will not be absolutely stationary in the future.
Sugimoto, Taiki; Yoshida, Masaki; Ono, Rei; Murata, Shunsuke; Saji, Naoki; Niida, Shumpei; Toba, Kenji; Sakurai, Takashi
2017-01-01
Urinary incontinence (UI) is frequently observed in patients with Alzheimer's disease (AD). Although previous works highlight the association between frontal lobe-related function and UI, causal relationship is unclear. To clarify the longitudinal association between frontal lobe function and the incidence of UI at 1 year in patients with AD. The subjects were 215 continent AD patients who attended the Memory Clinic of the National Center for Geriatrics and Gerontology of Japan during the period from March 2011 to December 2014. The absence or presence of UI was operationally assigned by the dementia behavior disturbance scale subscale, which was completed by the patients' caregivers. Frontal lobe function was assessed using the Frontal Assessment Battery (FAB). Other confounding factors including demographic data, cognitive status, vitality, mood, physical performance, and use of medication (cholinesterase inhibitors, calcium channel blockers [CCBs], diuretics, alpha blockers and anticholinergic drugs) were assessed. During 1-year follow up (mean: 377.4±83.7 days), the incidence of UI was 12.1% (n = 26). Patients with UI had significantly lower FAB performance at baseline (no UI versus UI = 9.3±2.8 versus 7.8±2.7). In multivariate analysis, stepwise logistic regression analysis demonstrated that FAB (odds ratio [OR] = 0.79, 95% confidence interval [CI] = 0.66-0.94) and the use of CCB (OR = 2.72, 95% CI = 1.09-6.77) were significantly associated with UI at 1 year. The results of study indicate that frontal lobe dysfunction is predictor for UI in patients with AD.
Functional Error Models to Accelerate Nested Sampling
Josset, L.; Elsheikh, A. H.; Demyanov, V.; Lunati, I.
2014-12-01
The main challenge in groundwater problems is the reliance on large numbers of unknown parameters with wide rage of associated uncertainties. To translate this uncertainty to quantities of interest (for instance the concentration of pollutant in a drinking well), a large number of forward flow simulations is required. To make the problem computationally tractable, Josset et al. (2013, 2014) introduced the concept of functional error models. It consists in two elements: a proxy model that is cheaper to evaluate than the full physics flow solver and an error model to account for the missing physics. The coupling of the proxy model and the error models provides reliable predictions that approximate the full physics model's responses. The error model is tailored to the problem at hand by building it for the question of interest. It follows a typical approach in machine learning where both the full physics and proxy models are evaluated for a training set (subset of realizations) and the set of responses is used to construct the error model using functional data analysis. Once the error model is devised, a prediction of the full physics response for a new geostatistical realization can be obtained by computing the proxy response and applying the error model. We propose the use of functional error models in a Bayesian inference context by combining it to the Nested Sampling (Skilling 2006; El Sheikh et al. 2013, 2014). Nested Sampling offers a mean to compute the Bayesian Evidence by transforming the multidimensional integral into a 1D integral. The algorithm is simple: starting with an active set of samples, at each iteration, the sample with the lowest likelihood is kept aside and replaced by a sample of higher likelihood. The main challenge is to find this sample of higher likelihood. We suggest a new approach: first the active set is sampled, both proxy and full physics models are run and the functional error model is build. Then, at each iteration of the Nested
Simulation model of lung cancer incidence related to smoking and radon daughter exposure
International Nuclear Information System (INIS)
Stolowijk, J.A.J.
1990-01-01
A mathematical model of lung cancer and radon daughter exposure is presented. It is aimed to provide a quantitative estimate in the form of dose-effect relationship. The nature of the cigarette smoking and radon exposure interaction it is shown to be a multiplicative or sub-multiplicative function rather than a simpler model in which the effect of the two exposures would be summed. The model was written in the SAS programming language. An annotated listing of the program is given. 4 refs
International Nuclear Information System (INIS)
Francois, P.
1996-01-01
We undertook a study programme at the end of 1991. To start with, we performed some exploratory studies aimed at learning some preliminary lessons on this type of analysis: Assessment of the interest of probabilistic incident analysis; possibility of using PSA scenarios; skills and resources required. At the same time, EPN created a working group whose assignment was to define a new approach for analysis of incidents on NPPs. This working group gave thought to both aspects of Operating Feedback that EPN wished to improve: Analysis of significant incidents; analysis of potential consequences. We took part in the work of this group, and for the second aspects, we proposed a method based on an adaptation of the event-tree method in order to establish a link between existing PSA models and actual incidents. Since PSA provides an exhaustive database of accident scenarios applicable to the two most common types of units in France, they are obviously of interest for this sort of analysis. With this method we performed some incident analyses, and at the same time explores some methods employed abroad, particularly ASP (Accident Sequence Precursor, a method used by the NRC). Early in 1994 EDF began a systematic analysis programme. The first, transient phase will set up methods and an organizational structure. 7 figs
International Nuclear Information System (INIS)
Iman, R.L.; Hora, S.C.
1988-01-01
Industry data representing the time to recovery of loss of off-site power at nuclear power plants for 63 incidents caused by plant-centered losses, grid losses, or severe weather losses are fit with exponential, lognormal, gamma and Weibull probability models. A Bayesian analysis is used to compare the adequacy of each of these models and to provide uncertainty bounds on each of the fitted models. A composite model that combines the probability models fitted to each of the three sources of data is presented as a method for predicting the time to recovery of loss of off-site power. The composite model is very general and can be made site specific by making adjustments on the models used, such as might occur due to the type of switchyard configuration or type of grid, and by adjusting the weights on the individual models, such as might occur with weather conditions existing at a particular plant. Adjustments in the composite model are shown for different models used for switchyard configuration and for different weights due to weather. Bayesian approaches are also presented for modeling the frequency of initiating events leading to loss of off-site power. One Bayesian model assumes that all plants share a common incidence rate for loss of off-site power, while the other Bayesian approach models the incidence rate for each plant relative to the incidence rates of all other plants. Combining the Bayesian models for the frequency of the initiating events with the composite Bayesian model for recovery provides the necessary vehicle for a complete model that incorporates uncertainty into a probabilistic risk assessment
Directory of Open Access Journals (Sweden)
Yulia G. Krasnozhon
2018-03-01
Full Text Available Modern information technologies have an increasing importance for development dynamics and management structure of an enterprise. The management efficiency of implementation of modern information technologies directly related to the quality of information security incident management. However, issues of assessment of the impact of information security incidents management on quality and efficiency of the enterprise management system are not sufficiently highlighted neither in Russian nor in foreign literature. The main direction to approach these problems is the optimization of the process automation system of the information security incident management. Today a special attention is paid to IT-technologies while dealing with information security incidents at mission-critical facilities in Russian Federation such as the Federal Tax Service of Russia (FTS. It is proposed to use the mathematical apparatus of queueing theory in order to build a mathematical model of the system optimization. The developed model allows to estimate quality of the management taking into account the rules and restrictions imposed on the system by the effects of information security incidents. Here an example is given in order to demonstrate the system in work. The obtained statistical data are shown. An implementation of the system discussed here will improve the quality of the Russian FTS services and make responses to information security incidents faster.
Directory of Open Access Journals (Sweden)
R.V. Tkach
2016-08-01
Full Text Available Today, the violations of the digestive system in children of the first years of life remain the actual problem of practical pediatrics and are the common cause for parents to visit a doctor. The importance in the genesis of functional disorders of the digestive system in children of this age may belongs to lactase deficiency. 327 children from Lviv were included in the questionnaire survey. The aim of the study was to evaluate the incidence of clinical symptoms that may be associated with lactase deficiency in infants. Among the clinical symptoms in young children, according to the survey, regurgitation and colic, stool disorders dominated. The diagnosis of lactase deficiency was established in 3.4 % (11 of children, 2.8 % (9 children received enzyme of lactase.
Incidence of social phobia and identification of its risk indicators: A model for prevention.
Acarturk, C.; Smit, H.F.E.; Graaf, de, R.; Straten, van, A.; Have, M. ten; Cuijpers, P.
2009-01-01
Objective: This study seeks to examine the incidence of social phobia in the general population and to establish a number of risk indicators. Method: Data were derived from the Netherlands Mental Health Survey and Incidence Study (NEMESIS) which is a population based prospective study (n = 7076). A sample of adults aged 18-64 years (n = 5618) were re-interviewed 1 year later using Composite International Diagnostic Interview (CIDI). Results: The 12-month incidence of DSM-III-R social phobia w...
International Nuclear Information System (INIS)
Toeroek, Szabolcs; Borgulya, Gabor; Lobmayer, Peter; Jakab, Zsuzsanna; Schuler, Dezsoe; Fekete, Gyoergy
2005-01-01
The incidence of childhood leukaemia in Hungary has yet to be reported, although data are available since the early 70s. The Hungarian data therefore cover the time before and after the Chernobyl nuclear accident (1986). The aim of this study was to assess the effects of the Chernobyl accident on childhood leukaemia incidence in Hungary. A population-based study was carried out using data of the National Paediatric Cancer Registry of Hungary from 1973 to 2002. The total number of cases was 2204. To test the effect of the Chernobyl accident the authors applied a new approach called 'Hypothesized Impact Period Interpolation'-model, which takes into account the increasing trend of childhood leukaemia incidence and the hypothesized exposure and latency times. The incidence of leukaemia in the age group 0-14 varied between 33.2 and 39.4 per million person-years along the observed 30 year period, and the incidence of childhood leukaemia showed a moderate increase of 0.71% annually (p=0.0105). In the period of the hypothesized impact of the Chernobyl accident the incidence rate was elevated by 2.5% (95% CI: -8.1%; +14.3%), but this change was not statistically significant (p=0.663). The age standardised incidence, the age distribution, the gender ratio, and the magnitude of increasing trend of childhood leukaemia incidence in Hungary were similar to other European countries. Applying the presented interpolation method the authors did not find a statistically significant increase in the leukaemia incidence in the period of the hypothesized impact of the Chernobyl accident
Directory of Open Access Journals (Sweden)
Artur Badyda
2016-11-01
Full Text Available It is essential in pulmonary disease research to take into account traffic-related air pollutant exposure among urban inhabitants. In our study, 4985 people were examined for spirometric parameters in the presented research which was conducted in the years 2008–2012. The research group was divided into urban and rural residents. Traffic density, traffic structure and velocity, as well as concentrations of selected air pollutants (CO, NO2 and PM10 were measured at selected areas. Among people who live in the city, lower percentages of predicted values of spirometric parameters were noticed in comparison to residents of rural areas. Taking into account that the difference in the five-year mean concentration of PM10 in the considered city and rural areas was over 17 μg/m3, each increase of PM10 by 10 μg/m3 is associated with the decline in FEV1 (forced expiratory volume during the first second of expiration by 1.68%. These findings demonstrate that traffic-related air pollutants may have a significant influence on the decline of pulmonary function and the growing rate of respiratory diseases.
International Nuclear Information System (INIS)
Kai, Michiaki; Kusama, Tomoko
2000-01-01
Breast cancer incidence is the highest risk due to radiation among atomic bomb survivors. The excess relative risk of the early-onset breast cancer seems to be remarkably high for the youngest age-at-exposure groups. The cancer risk estimate of breast cancer is a current issue in radiological protection. We used a two-stage stochastic model for carcinogenesis to analyze the breast cancer incidence among atomic bomb survivors (Kai, et al. Radiat. Res. 1997). Our purpose is to examine the dependence of radiation risk on age at exposure using the two-stage model and how to transfer it to other populations for radiological protection. We fitted the model assuming that radiation acts as an initiator and that the rate of radiation-induced mutation and background initiation mutation leading to baseline cancer are additive. We took two age-dependence, not attained age but age at exposure, of the spontaneous process into account. First, age-dependence of spontaneous initiation was expressed by a linear model. We also modeled the age-dependence of spontaneous net growth rate of initiated cells by a linear function. As far as radiation-induced initiation is concerned, we took a stepwise function other than a liner function into account. The analysis did not show that the radiation mutation for the youngest age-at-exposure groups below age 10 was higher than for the older groups. Furthermore, the incidence of female breast cancer in Japan is increasing and the birth cohort effect can be observed in atomic bomb survivors. Our model assumed that an acute exposure to atomic radiation can only initiate cancers and do not influence other stages of carcinogenesis, whereas spontaneous initiation and promotion are age-dependent to consider birth cohort effects. When these cohort effects are properly accounted for, the shape of the age-specific incidence curve in Japan is remarkably similar to the age-specific incidence in western populations (shown in figure). Recently Little and
The Incidence of Positive Modifications to Nerve Conduits in Rodent Nerve Repair Models
Patel, Tejas T.; Isaacs, Jonathan
2016-01-01
Background: The nerve conduit is a generally accepted tool to facilitate the repair of short nerve gaps. Limitations in effectiveness have been recognized, and a steady stream of possible conduit improvements has been published in the scientific literature. Analysis of this information, particularly when small animal models have been utilized, seems to indicate that nearly any modification of a nerve conduit improves outcomes in repairs of short gaps over standard nerve conduits. This seems statistically and biologically improbable and suggests a bias in the literature. Methods: A standardized systemic review of the scientific literature on rodent model studies assessing conduit modifications was undertaken to determine the incidence of positive or supportive outcomes. Results: Modifications were deemed superior in 97.3% of studies when compared with unmodified conduits and deemed equivalent or superior in 52.1% of studies when compared with autograft. Conclusions: A seemingly disproportionate number of positive results suggest that the literature on nerve conduit modifications may be skewed. We believe that there is a publication bias in the literature, and this warrants further investigation. PMID:27418898
Su, Anping; Gong, Yanping; Wu, Wenshuang; Gong, Rixiang; Li, Zhihui; Zhu, Jingqiang
2018-02-02
The relationship between the number of parathyroid glands autotransplanted and hypoparathyroidism as well as recovery of parathyroid function is not understood fully. The aim was to ascertain whether the number of autotransplanted glands affected the incidence of hypoparathyroidism and recovery of parathyroid function in long-term follow-up after thyroidectomy. A retrospective cohort study included all patients with papillary thyroid carcinoma who underwent first-time total thyroidectomy with central neck dissection between June 2012 and June 2015. The patients were divided into 4 groups (0, 1, 2, and 3) on the basis of the number of parathyroid glands autotransplanted. Of the 766 patients, 283 (36.9%) had no gland autotransplanted, and 373 (48.7%), 97 (12.7%), and 13 (1.7%) had 1, 2, and 3 glands autotransplanted, respectively. More lymph nodes and more metastatic ones in the central compartment were retrieved in groups 2 and 3 (P .05). The recovery rates of serum parathyroid hormone concentration were 84.7%, 82.2%, 82.0%, and 79.2% after 2-year follow-up (P > .05). Autotransplantation is an effective strategy for restoration of parathyroid function. Transient hypoparathyroidism is positively correlated to the number of autotransplanted parathyroid glands during total thyroidectomy with central neck dissection. There is no increase in permanent hypoparathyroidism in patients with a higher number of autotransplanted glands, despite more extensive lymph node disease. (Surgery 2018;161:XXX-XXX.). Copyright © 2017 Elsevier Inc. All rights reserved.
Bayesian Modelling of Functional Whole Brain Connectivity
DEFF Research Database (Denmark)
Røge, Rasmus
This thesis deals with parcellation of whole-brain functional magnetic resonance imaging (fMRI) using Bayesian inference with mixture models tailored to the fMRI data. In the three included papers and manuscripts, we analyze two different approaches to modeling fMRI signal; either we accept...... the prevalent strategy of standardizing of fMRI time series and model data using directional statistics or we model the variability in the signal across the brain and across multiple subjects. In either case, we use Bayesian nonparametric modeling to automatically learn from the fMRI data the number...... of funcional units, i.e. parcels. We benchmark the proposed mixture models against state of the art methods of brain parcellation, both probabilistic and non-probabilistic. The time series of each voxel are most often standardized using z-scoring which projects the time series data onto a hypersphere...
Frost heave modelling using porosity rate function
Michalowski, Radoslaw L.; Zhu, Ming
2006-07-01
Frost-susceptible soils are characterized by their sensitivity to freezing that is manifested in heaving of the ground surface. While significant contributions to explaining the nature of frost heave in soils were published in late 1920s, modelling efforts did not start until decades later. Several models describing the heaving process have been developed in the past, but none of them has been generally accepted as a tool in engineering applications. The approach explored in this paper is based on the concept of the porosity rate function dependent on two primary material parameters: the maximum rate, and the temperature at which the maximum rate occurs. The porosity rate is indicative of ice growth, and this growth is also dependent on the temperature gradient and the stress state in the freezing soil. The advantage of this approach over earlier models stems from a formulation consistent with continuum mechanics that makes it possible to generalize the model to arbitrary three-dimensional processes, and use the standard numerical techniques in solving boundary value problems. The physical premise for the model is discussed first, and the development of the constitutive model is outlined. The model is implemented in a 2-D finite element code, and the porosity rate function is calibrated and validated. Effectiveness of the model is then illustrated in an example of freezing of a vertical cut in frost-susceptible soil.
A systemic approach for modeling soil functions
Vogel, Hans-Jörg; Bartke, Stephan; Daedlow, Katrin; Helming, Katharina; Kögel-Knabner, Ingrid; Lang, Birgit; Rabot, Eva; Russell, David; Stößel, Bastian; Weller, Ulrich; Wiesmeier, Martin; Wollschläger, Ute
2018-03-01
The central importance of soil for the functioning of terrestrial systems is increasingly recognized. Critically relevant for water quality, climate control, nutrient cycling and biodiversity, soil provides more functions than just the basis for agricultural production. Nowadays, soil is increasingly under pressure as a limited resource for the production of food, energy and raw materials. This has led to an increasing demand for concepts assessing soil functions so that they can be adequately considered in decision-making aimed at sustainable soil management. The various soil science disciplines have progressively developed highly sophisticated methods to explore the multitude of physical, chemical and biological processes in soil. It is not obvious, however, how the steadily improving insight into soil processes may contribute to the evaluation of soil functions. Here, we present to a new systemic modeling framework that allows for a consistent coupling between reductionist yet observable indicators for soil functions with detailed process understanding. It is based on the mechanistic relationships between soil functional attributes, each explained by a network of interacting processes as derived from scientific evidence. The non-linear character of these interactions produces stability and resilience of soil with respect to functional characteristics. We anticipate that this new conceptional framework will integrate the various soil science disciplines and help identify important future research questions at the interface between disciplines. It allows the overwhelming complexity of soil systems to be adequately coped with and paves the way for steadily improving our capability to assess soil functions based on scientific understanding.
The Goodwin model: behind the Hill function.
Directory of Open Access Journals (Sweden)
Didier Gonze
Full Text Available The Goodwin model is a 3-variable model demonstrating the emergence of oscillations in a delayed negative feedback-based system at the molecular level. This prototypical model and its variants have been commonly used to model circadian and other genetic oscillators in biology. The only source of non-linearity in this model is a Hill function, characterizing the repression process. It was mathematically shown that to obtain limit-cycle oscillations, the Hill coefficient must be larger than 8, a value often considered unrealistic. It is indeed difficult to explain such a high coefficient with simple cooperative dynamics. We present here molecular models of the standard Goodwin model, based on single or multisite phosphorylation/dephosphorylation processes of a transcription factor, which have been previously shown to generate switch-like responses. We show that when the phosphorylation/dephosphorylation processes are fast enough, the limit-cycle obtained with a multisite phosphorylation-based mechanism is in very good quantitative agreement with the oscillations observed in the Goodwin model. Conditions in which the detailed mechanism is well approximated by the Goodwin model are given. A variant of the Goodwin model which displays sharp thresholds and relaxation oscillations is also explained by a double phosphorylation/dephosphorylation-based mechanism through a bistable behavior. These results not only provide rational support for the Goodwin model but also highlight the crucial role of the speed of post-translational processes, whose response curve are usually established at a steady state, in biochemical oscillators.
Correlation functions of two-matrix models
International Nuclear Information System (INIS)
Bonora, L.; Xiong, C.S.
1993-11-01
We show how to calculate correlation functions of two matrix models without any approximation technique (except for genus expansion). In particular we do not use any continuum limit technique. This allows us to find many solutions which are invisible to the latter technique. To reach our goal we make full use of the integrable hierarchies and their reductions which were shown in previous papers to naturally appear in multi-matrix models. The second ingredient we use, even though to a lesser extent, are the W-constraints. In fact an explicit solution of the relevant hierarchy, satisfying the W-constraints (string equation), underlies the explicit calculation of the correlation functions. The correlation functions we compute lend themselves to a possible interpretation in terms of topological field theories. (orig.)
Talmoudi, Khouloud; Bellali, Hedia; Ben-Alaya, Nissaf; Saez, Marc; Malouche, Dhafer; Chahed, Mohamed Kouni
2017-08-01
Transmission of zoonotic cutaneous leishmaniasis (ZCL) depends on the presence, density and distribution of Leishmania major rodent reservoir and the development of these rodents is known to have a significant dependence on environmental and climate factors. ZCL in Tunisia is one of the most common forms of leishmaniasis. The aim of this paper was to build a regression model of ZCL cases to identify the relationship between ZCL occurrence and possible risk factors, and to develop a predicting model for ZCL's control and prevention purposes. Monthly reported ZCL cases, environmental and bioclimatic data were collected over 6 years (2009-2015). Three rural areas in the governorate of Sidi Bouzid were selected as the study area. Cross-correlation analysis was used to identify the relevant lagged effects of possible risk factors, associated with ZCL cases. Non-parametric modeling techniques known as generalized additive model (GAM) and generalized additive mixed models (GAMM) were applied in this work. These techniques have the ability to approximate the relationship between the predictors (inputs) and the response variable (output), and express the relationship mathematically. The goodness-of-fit of the constructed model was determined by Generalized cross-validation (GCV) score and residual test. There were a total of 1019 notified ZCL cases from July 2009 to June 2015. The results showed seasonal distribution of reported ZCL cases from August to January. The model highlighted that rodent density, average temperature, cumulative rainfall and average relative humidity, with different time lags, all play role in sustaining and increasing the ZCL incidence. The GAMM model could be applied to predict the occurrence of ZCL in central Tunisia and could help for the establishment of an early warning system to control and prevent ZCL in central Tunisia.
Directory of Open Access Journals (Sweden)
Khouloud Talmoudi
2017-08-01
Full Text Available Transmission of zoonotic cutaneous leishmaniasis (ZCL depends on the presence, density and distribution of Leishmania major rodent reservoir and the development of these rodents is known to have a significant dependence on environmental and climate factors. ZCL in Tunisia is one of the most common forms of leishmaniasis. The aim of this paper was to build a regression model of ZCL cases to identify the relationship between ZCL occurrence and possible risk factors, and to develop a predicting model for ZCL's control and prevention purposes. Monthly reported ZCL cases, environmental and bioclimatic data were collected over 6 years (2009-2015. Three rural areas in the governorate of Sidi Bouzid were selected as the study area. Cross-correlation analysis was used to identify the relevant lagged effects of possible risk factors, associated with ZCL cases. Non-parametric modeling techniques known as generalized additive model (GAM and generalized additive mixed models (GAMM were applied in this work. These techniques have the ability to approximate the relationship between the predictors (inputs and the response variable (output, and express the relationship mathematically. The goodness-of-fit of the constructed model was determined by Generalized cross-validation (GCV score and residual test. There were a total of 1019 notified ZCL cases from July 2009 to June 2015. The results showed seasonal distribution of reported ZCL cases from August to January. The model highlighted that rodent density, average temperature, cumulative rainfall and average relative humidity, with different time lags, all play role in sustaining and increasing the ZCL incidence. The GAMM model could be applied to predict the occurrence of ZCL in central Tunisia and could help for the establishment of an early warning system to control and prevent ZCL in central Tunisia.
Hazard identification based on plant functional modelling
International Nuclear Information System (INIS)
Rasmussen, B.; Whetton, C.
1993-10-01
A major objective of the present work is to provide means for representing a process plant as a socio-technical system, so as to allow hazard identification at a high level. The method includes technical, human and organisational aspects and is intended to be used for plant level hazard identification so as to identify critical areas and the need for further analysis using existing methods. The first part of the method is the preparation of a plant functional model where a set of plant functions link together hardware, software, operations, work organisation and other safety related aspects of the plant. The basic principle of the functional modelling is that any aspect of the plant can be represented by an object (in the sense that this term is used in computer science) based upon an Intent (or goal); associated with each Intent are Methods, by which the Intent is realized, and Constraints, which limit the Intent. The Methods and Constraints can themselves be treated as objects and decomposed into lower-level Intents (hence the procedure is known as functional decomposition) so giving rise to a hierarchical, object-oriented structure. The plant level hazard identification is carried out on the plant functional model using the Concept Hazard Analysis method. In this, the user will be supported by checklists and keywords and the analysis is structured by pre-defined worksheets. The preparation of the plant functional model and the performance of the hazard identification can be carried out manually or with computer support. (au) (4 tabs., 10 ills., 7 refs.)
Tan, Ting; Chen, Lizhang; Liu, Fuqiang
2014-11-01
To establish multiple seasonal autoregressive integrated moving average model (ARIMA) according to the hand-foot-mouth disease incidence in Changsha, and to explore the feasibility of the multiple seasonal ARIMA in predicting the hand-foot-mouth disease incidence. EVIEWS 6.0 was used to establish multiple seasonal ARIMA according to the hand-foot- mouth disease incidence from May 2008 to August 2013 in Changsha, and the data of the hand- foot-mouth disease incidence from September 2013 to February 2014 were served as the examined samples of the multiple seasonal ARIMA, then the errors were compared between the forecasted incidence and the real value. Finally, the incidence of hand-foot-mouth disease from March 2014 to August 2014 was predicted by the model. After the data sequence was handled by smooth sequence, model identification and model diagnosis, the multiple seasonal ARIMA (1, 0, 1)×(0, 1, 1)12 was established. The R2 value of the model fitting degree was 0.81, the root mean square prediction error was 8.29 and the mean absolute error was 5.83. The multiple seasonal ARIMA is a good prediction model, and the fitting degree is good. It can provide reference for the prevention and control work in hand-foot-mouth disease.
Incidence of social phobia and identification of its risk indicators: A model for prevention.
Acarturk, C.; Smit, H.F.E.; de Graaf, R.; van Straten, A.; ten Have, M.; Cuijpers, P.
2009-01-01
Objective: This study seeks to examine the incidence of social phobia in the general population and to establish a number of risk indicators. Method: Data were derived from the Netherlands Mental Health Survey and Incidence Study (NEMESIS) which is a population based prospective study (n = 7076). A
Daberkow, Kevin S.; Lin, Wei
2012-01-01
Nearly half a century of lottery scholarship has measured lottery tax incidence predominantly through either the Suits Index or regression analysis. The present study builds on historic lottery tax burden measurement to present a comprehensive set of tools to determine the tax incidence of individual games in addition to determining which lottery…
He, Fei; Hu, Zhi-Jian; Zhang, Wen-Chang; Cai, Lin; Cai, Guo-Xi; Aoyagi, Kiyoshi
2017-08-03
It remains challenging to forecast local, seasonal outbreaks of influenza. The goal of this study was to construct a computational model for predicting influenza incidence. We built two computational models including an Autoregressive Distributed Lag (ARDL) model and a hybrid model integrating ARDL with a Generalized Regression Neural Network (GRNN), to assess meteorological factors associated with temporal trends in influenza incidence. The modelling and forecasting performance of these two models were compared using observations collected between 2006 and 2015 in Nagasaki Prefecture, Japan. In both the training and forecasting stages, the hybrid model showed lower error rates, including a lower residual mean square error (RMSE) and mean absolute error (MAE) than the ARDL model. The lag of log-incidence, weekly average barometric pressure, and weekly average of air temperature were 4, 1, and 3, respectively in the ARDL model. The ARDL-GRNN hybrid model can serve as a tool to better understand the characteristics of influenza epidemic, and facilitate their prevention and control.
Li, Jian; Gu, Jun-zhong; Mao, Sheng-hua; Xiao, Wen-jia; Jin, Hui-ming; Zheng, Ya-xu; Wang, Yong-ming; Hu, Jia-yu
2013-12-01
To establish BP artificial neural network predicting model regarding the daily cases of infectious diarrhea in Shanghai. Data regarding both the incidence of infectious diarrhea from 2005 to 2008 in Shanghai and meteorological factors including temperature, relative humidity, rainfall, atmospheric pressure, duration of sunshine and wind speed within the same periods were collected and analyzed with the MatLab R2012b software. Meteorological factors that were correlated with infectious diarrhea were screened by Spearman correlation analysis. Principal component analysis (PCA) was used to remove the multi-colinearities between meteorological factors. Back-Propagation (BP) neural network was employed to establish related prediction models regarding the daily infectious diarrhea incidence, using artificial neural networks toolbox. The established models were evaluated through the fitting, predicting and forecasting processes. Data from Spearman correlation analysis indicated that the incidence of infectious diarrhea had a highly positive correlation with factors as daily maximum temperature, minimum temperature, average temperature, minimum relative humidity and average relative humidity in the previous two days (P neural network model were established under the input of 4 meteorological principal components, extracted by PCA and used for training and prediction. Then appeared to be 4.7811, 6.8921,0.7918,0.8418 and 5.8163, 7.8062,0.7202,0.8180, respectively. The rate on mean error regarding the predictive value to actual incidence in 2008 was 5.30% and the forecasting precision reached 95.63% . Temperature and air pressure showed important impact on the incidence of infectious diarrhea. The BP neural network model had the advantages of low simulation forecasting errors and high forecasting hit rate that could ideally predict and forecast the effects on the incidence of infectious diarrhea.
Symmetric Functional Model for Extensions of Hermitian
Ryzhov, V
2006-01-01
This paper offers the functional model of a class of non-selfadjoint extensions of a Hermitian operator with equal deficiency indices. The explicit form of dilation of a dissipative extension is offered and the symmetric form of Sz.Nagy-Foia\\c{s} model as developed by B.~Pavlov is constructed. A variant of functional model for a general non-selfadjoint non-dissipative extension is formulated. We illustrate the theory by two examples: singular perturbations of the Laplace operator in~$L_2(\\Real^3)$ by a finite number of point interactions, and the Schr\\"odinger operator on the half axis~$(0, \\infty)$ in the Weyl limit circle case at infinity.
Mathematical modeling and visualization of functional neuroimages
DEFF Research Database (Denmark)
Rasmussen, Peter Mondrup
This dissertation presents research results regarding mathematical modeling in the context of the analysis of functional neuroimages. Specifically, the research focuses on pattern-based analysis methods that recently have become popular within the neuroimaging community. Such methods attempt...... to predict or decode experimentally defined cognitive states based on brain scans. The topics covered in the dissertation are divided into two broad parts: The first part investigates the relative importance of model selection on the brain patterns extracted form analysis models. Typical neuroimaging data...... for extracting a global summary map from a trained model. Such summary maps provides the investigator with an overview of brain locations of importance to the model’s predictions. The sensitivity map proves as a versatile technique for model visualization. Furthermore, we perform a preliminary investigation...
Mathematical modeling and visualization of functional neuroimages
DEFF Research Database (Denmark)
Rasmussen, Peter Mondrup
This dissertation presents research results regarding mathematical modeling in the context of the analysis of functional neuroimages. Specifically, the research focuses on pattern-based analysis methods that recently have become popular analysis tools within the neuroimaging community. Such methods...... attempt to predict or decode experimentally defined cognitive states based on brain scans. The topics covered in the dissertation are divided into two broad parts: The first part investigates the relative importance of model selection on the brain patterns extracted form analysis models. Typical...... for extracting a global summary map from a trained model. Such summary maps provides the investigator with an overview of brain locations of importance to the model’s predictions. The sensitivity map proves as a versatile technique for model visualization. Furthermore, we perform a preliminary investigation...
Directory of Open Access Journals (Sweden)
Erfan Ayubi
2017-05-01
Full Text Available OBJECTIVES The aim of this study was to explore the spatial pattern of female breast cancer (BC incidence at the neighborhood level in Tehran, Iran. METHODS The present study included all registered incident cases of female BC from March 2008 to March 2011. The raw standardized incidence ratio (SIR of BC for each neighborhood was estimated by comparing observed cases relative to expected cases. The estimated raw SIRs were smoothed by a Besag, York, and Mollie spatial model and the spatial empirical Bayesian method. The purely spatial scan statistic was used to identify spatial clusters. RESULTS There were 4,175 incident BC cases in the study area from 2008 to 2011, of which 3,080 were successfully geocoded to the neighborhood level. Higher than expected rates of BC were found in neighborhoods located in northern and central Tehran, whereas lower rates appeared in southern areas. The most likely cluster of higher than expected BC incidence involved neighborhoods in districts 3 and 6, with an observed-to-expected ratio of 3.92 (p<0.001, whereas the most likely cluster of lower than expected rates involved neighborhoods in districts 17, 18, and 19, with an observed-to-expected ratio of 0.05 (p<0.001. CONCLUSIONS Neighborhood-level inequality in the incidence of BC exists in Tehran. These findings can serve as a basis for resource allocation and preventive strategies in at-risk areas.
Ding, L; Li, J; Wang, C; Li, X; Su, Q; Zhang, G; Xue, F
2017-09-01
Prediction models of atrial fibrillation (AF) have been developed; however, there was no AF prediction model validated in Chinese population. Therefore, we aimed to investigate the incidence of AF in urban Han Chinese health check-up population, as well as to develop AF prediction models using behavioral, anthropometric, biochemical, electrocardiogram (ECG) markers, as well as visit-to-visit variability (VVV) in blood pressures available in the routine health check-up. A total of 33 186 participants aged 45-85 years and free of AF at baseline were included in this cohort, to follow up for incident AF with an annually routine health check-up. Cox regression models were used to develop AF prediction model and 10-fold cross-validation was used to test the discriminatory accuracy of prediction model. We developed three prediction models, with age, sex, history of coronary heart disease (CHD), hypertension as predictors for simple model, with left high-amplitude waves, premature beats added for ECG model, and with age, sex, history of CHD and VVV in systolic and diabolic blood pressures as predictors for VVV model, to estimate risk of incident AF. The calibration of our models ranged from 1.001 to 1.004 (P for Hosmer Lemeshow test >0.05). The area under receiver operator characteristics curve were 78%, 80% and 82%, respectively, for predicting risk of AF. In conclusion, we have identified predictors of incident AF and developed prediction models for AF with variables readily available in routine health check-up.
Modeling dynamic functional connectivity using a wishart mixture model
DEFF Research Database (Denmark)
Nielsen, Søren Føns Vind; Madsen, Kristoffer Hougaard; Schmidt, Mikkel Nørgaard
2017-01-01
Dynamic functional connectivity (dFC) has recently become a popular way of tracking the temporal evolution of the brains functional integration. However, there does not seem to be a consensus on how to choose the complexity, i.e. number of brain states, and the time-scale of the dynamics, i.......e. the window length. In this work we use the Wishart Mixture Model (WMM) as a probabilistic model for dFC based on variational inference. The framework admits arbitrary window lengths and number of dynamic components and includes the static one-component model as a special case. We exploit that the WMM...... framework provides model selection by quantifying models generalization to new data. We use this to quantify the number of states within a prespecified window length. We further propose a heuristic procedure for choosing the window length based on contrasting for each window length the predictive...
Multivariate Heteroscedasticity Models for Functional Brain Connectivity
Directory of Open Access Journals (Sweden)
Christof Seiler
2017-12-01
Full Text Available Functional brain connectivity is the co-occurrence of brain activity in different areas during resting and while doing tasks. The data of interest are multivariate timeseries measured simultaneously across brain parcels using resting-state fMRI (rfMRI. We analyze functional connectivity using two heteroscedasticity models. Our first model is low-dimensional and scales linearly in the number of brain parcels. Our second model scales quadratically. We apply both models to data from the Human Connectome Project (HCP comparing connectivity between short and conventional sleepers. We find stronger functional connectivity in short than conventional sleepers in brain areas consistent with previous findings. This might be due to subjects falling asleep in the scanner. Consequently, we recommend the inclusion of average sleep duration as a covariate to remove unwanted variation in rfMRI studies. A power analysis using the HCP data shows that a sample size of 40 detects 50% of the connectivity at a false discovery rate of 20%. We provide implementations using R and the probabilistic programming language Stan.
A Generic Modeling Process to Support Functional Fault Model Development
Maul, William A.; Hemminger, Joseph A.; Oostdyk, Rebecca; Bis, Rachael A.
2016-01-01
Functional fault models (FFMs) are qualitative representations of a system's failure space that are used to provide a diagnostic of the modeled system. An FFM simulates the failure effect propagation paths within a system between failure modes and observation points. These models contain a significant amount of information about the system including the design, operation and off nominal behavior. The development and verification of the models can be costly in both time and resources. In addition, models depicting similar components can be distinct, both in appearance and function, when created individually, because there are numerous ways of representing the failure space within each component. Generic application of FFMs has the advantages of software code reuse: reduction of time and resources in both development and verification, and a standard set of component models from which future system models can be generated with common appearance and diagnostic performance. This paper outlines the motivation to develop a generic modeling process for FFMs at the component level and the effort to implement that process through modeling conventions and a software tool. The implementation of this generic modeling process within a fault isolation demonstration for NASA's Advanced Ground System Maintenance (AGSM) Integrated Health Management (IHM) project is presented and the impact discussed.
A mathematical model of avian influenza with half-saturated incidence.
Chong, Nyuk Sian; Tchuenche, Jean Michel; Smith, Robert J
2014-03-01
The widespread impact of avian influenza viruses not only poses risks to birds, but also to humans. The viruses spread from birds to humans and from human to human In addition, mutation in the primary strain will increase the infectiousness of avian influenza. We developed a mathematical model of avian influenza for both bird and human populations. The effect of half-saturated incidence on transmission dynamics of the disease is investigated. The half-saturation constants determine the levels at which birds and humans contract avian influenza. To prevent the spread of avian influenza, the associated half-saturation constants must be increased, especially the half-saturation constant H m for humans with mutant strain. The quantity H m plays an essential role in determining the basic reproduction number of this model. Furthermore, by decreasing the rate β m at which human-to-human mutant influenza is contracted, an outbreak can be controlled more effectively. To combat the outbreak, we propose both pharmaceutical (vaccination) and non-pharmaceutical (personal protection and isolation) control methods to reduce the transmission of avian influenza. Vaccination and personal protection will decrease β m, while isolation will increase H m. Numerical simulations demonstrate that all proposed control strategies will lead to disease eradication; however, if we only employ vaccination, it will require slightly longer to eradicate the disease than only applying non-pharmaceutical or a combination of pharmaceutical and non-pharmaceutical control methods. In conclusion, it is important to adopt a combination of control methods to fight an avian influenza outbreak.
Directory of Open Access Journals (Sweden)
Roman Bauer
Full Text Available Glioma is the most common form of primary brain tumor. Demographically, the risk of occurrence increases until old age. Here we present a novel computational model to reproduce the probability of glioma incidence across the lifespan. Previous mathematical models explaining glioma incidence are framed in a rather abstract way, and do not directly relate to empirical findings. To decrease this gap between theory and experimental observations, we incorporate recent data on cellular and molecular factors underlying gliomagenesis. Since evidence implicates the adult neural stem cell as the likely cell-of-origin of glioma, we have incorporated empirically-determined estimates of neural stem cell number, cell division rate, mutation rate and oncogenic potential into our model. We demonstrate that our model yields results which match actual demographic data in the human population. In particular, this model accounts for the observed peak incidence of glioma at approximately 80 years of age, without the need to assert differential susceptibility throughout the population. Overall, our model supports the hypothesis that glioma is caused by randomly-occurring oncogenic mutations within the neural stem cell population. Based on this model, we assess the influence of the (experimentally indicated decrease in the number of neural stem cells and increase of cell division rate during aging. Our model provides multiple testable predictions, and suggests that different temporal sequences of oncogenic mutations can lead to tumorigenesis. Finally, we conclude that four or five oncogenic mutations are sufficient for the formation of glioma.
Lofgren, Eric T; Moehring, Rebekah W; Anderson, Deverick J; Weber, David J; Fefferman, Nina H
2014-01-01
Fecal microbiota transplantation (FMT) has been suggested as a new treatment to manage Clostridium difficile infection (CDI). With use of a mathematical model of C. difficile within an intensive care unit (ICU), we examined the potential impact of routine FMT. A mathematical model of C. difficile transmission, supplemented with prospective cohort, surveillance, and billing data from hospitals in the southeastern United States. Cohort, surveillance, and billing data as well as data from the literature were used to construct a compartmental model of CDI within an ICU. Patients were defined as being in 1 of 6 potential health states: uncolonized and at low risk; uncolonized and at high risk; colonized and at low risk; colonized and at high risk; having CDI; or treated with FMT. The use of FMT to treat patients after CDI was associated with a statistically significant reduction in recurrence but not with a reduction in incident cases. Treatment after administration of high-risk medications, such as antibiotics, did not result in a decrease in recurrence but did result in a statistically significant difference in incident cases across treatment groups, although whether this difference was clinically relevant was questionable. Our study is a novel mathematical model that examines the effect of FMT on the prevention of recurrent and incident CDI. The routine use of FMT represents a promising approach to reduce complex recurrent cases, but a reduction in CDI incidence will require the use of other methods to prevent transmission.
International Nuclear Information System (INIS)
Ruben, A.; Maerten, H.; Seeliger, D.
1990-01-01
A complex statistical theory of fission neutron emission combined with a phenomenological fission model has been used to calculate fission neutron data for 238 U. Obtained neutron multiplicities and energy spectra as well as average fragment energies for incidence energies from threshold to 20 MeV (including multiple-chance fission) are compared with traditional data representations. (author). 19 refs, 6 figs
Functional Security Model: Managers Engineers Working Together
Guillen, Edward Paul; Quintero, Rulfo
2008-05-01
Information security has a wide variety of solutions including security policies, network architectures and technological applications, they are usually designed and implemented by security architects, but in its own complexity this solutions are difficult to understand by company managers and they are who finally fund the security project. The main goal of the functional security model is to achieve a solid security platform reliable and understandable in the whole company without leaving of side the rigor of the recommendations and the laws compliance in a single frame. This paper shows a general scheme of the model with the use of important standards and tries to give an integrated solution.
Boyle, Todd A; Mahaffey, Thomas; Mackinnon, Neil J; Deal, Heidi; Hallstrom, Lars K; Morgan, Holly
2011-03-01
Evidence suggests that the underreporting of medication errors and near misses, collectively referred to as medication incidents (MIs), in the community pharmacy setting, is high. Despite the obvious negative implications, MIs present opportunities for pharmacy staff and regulatory authorities to learn from these mistakes and take steps to reduce the likelihood that they reoccur. However, these activities can only take place if such errors are reported and openly discussed. This research proposes a model of factors influencing the reporting, service recovery, and organizational learning resulting from MIs within Canadian community pharmacies. The conceptual model is based on a synthesis of the literature and findings from a pilot study conducted among pharmacy management, pharmacists, and pharmacy technicians from 13 community pharmacies in Nova Scotia, Canada. The purpose of the pilot study was to identify various actions that should be taken to improve MI reporting and included staff perceptions of the strengths and weaknesses of their current MI-reporting process, desired characteristics of a new process, and broader external and internal activities that would likely improve reporting. Out of the 109 surveys sent, 72 usable surveys were returned (66.1% response rate). Multivariate analysis of variance found no significant differences among staff type in their perceptions of the current or new desired system but were found for broader initiatives to improve MI reporting. These findings were used for a proposed structural equation model (SEM). The SEM proposes that individual-perceived self-efficacy, MI process capability, MI process support, organizational culture, management support, and regulatory authority all influence the completeness of MI reporting, which, in turn, influences MI service recovery and learning. This model may eventually be used to enable pharmacy managers to make better decisions. By identifying risk factors that contribute to low MI
Madankan, Reza
All across the world, toxic material clouds are emitted from sources, such as industrial plants, vehicular traffic, and volcanic eruptions can contain chemical, biological or radiological material. With the growing fear of natural, accidental or deliberate release of toxic agents, there is tremendous interest in precise source characterization and generating accurate hazard maps of toxic material dispersion for appropriate disaster management. In this dissertation, an end-to-end framework has been developed for probabilistic source characterization and forecasting of atmospheric release incidents. The proposed methodology consists of three major components which are combined together to perform the task of source characterization and forecasting. These components include Uncertainty Quantification, Optimal Information Collection, and Data Assimilation. Precise approximation of prior statistics is crucial to ensure performance of the source characterization process. In this work, an efficient quadrature based method has been utilized for quantification of uncertainty in plume dispersion models that are subject to uncertain source parameters. In addition, a fast and accurate approach is utilized for the approximation of probabilistic hazard maps, based on combination of polynomial chaos theory and the method of quadrature points. Besides precise quantification of uncertainty, having useful measurement data is also highly important to warranty accurate source parameter estimation. The performance of source characterization is highly affected by applied sensor orientation for data observation. Hence, a general framework has been developed for the optimal allocation of data observation sensors, to improve performance of the source characterization process. The key goal of this framework is to optimally locate a set of mobile sensors such that measurement of textit{better} data is guaranteed. This is achieved by maximizing the mutual information between model predictions
Directory of Open Access Journals (Sweden)
Jennifer M Yeh
Full Text Available Although gastric cancer has declined dramatically in the US, the disease remains the second leading cause of cancer mortality worldwide. A better understanding of reasons for the decline can provide important insights into effective preventive strategies. We sought to estimate the contribution of risk factor trends on past and future intestinal-type noncardia gastric adenocarcinoma (NCGA incidence.We developed a population-based microsimulation model of intestinal-type NCGA and calibrated it to US epidemiologic data on precancerous lesions and cancer. The model explicitly incorporated the impact of Helicobacter pylori and smoking on disease natural history, for which birth cohort-specific trends were derived from the National Health and Nutrition Examination Survey (NHANES and National Health Interview Survey (NHIS. Between 1978 and 2008, the model estimated that intestinal-type NCGA incidence declined 60% from 11.0 to 4.4 per 100,000 men, <3% discrepancy from national statistics. H. pylori and smoking trends combined accounted for 47% (range = 30%-58% of the observed decline. With no tobacco control, incidence would have declined only 56%, suggesting that lower smoking initiation and higher cessation rates observed after the 1960s accelerated the relative decline in cancer incidence by 7% (range = 0%-21%. With continued risk factor trends, incidence is projected to decline an additional 47% between 2008 and 2040, the majority of which will be attributable to H. pylori and smoking (81%; range = 61%-100%. Limitations include assuming all other risk factors influenced gastric carcinogenesis as one factor and restricting the analysis to men.Trends in modifiable risk factors explain a significant proportion of the decline of intestinal-type NCGA incidence in the US, and are projected to continue. Although past tobacco control efforts have hastened the decline, full benefits will take decades to be realized, and further discouragement of smoking and
[Upper Austria model study to assess the prevalence and incidence of congenital abnormalities].
Schaller, A; Vutuc, C; Bartsch, F; Bodingbauer, G; Bodingbauer, J; Fiedler, T; Fröhlich, H; Golob, E; Gotschall, J; Gruber, L
1987-04-30
Among the 15.998 live births recorded in Upper Austria in the year 1985, a representative malformation rate of 1.79, respectively a representative incidence of 17.94 in 1000 live births is reported. The incidences of characteristic malformations and of single malformations combined in malformation groups are determined. An instrument of investigation, especially developed for and successfully used in this examination in form of an illustrated questionnaire is introduced.
A general phenomenological model for work function
Brodie, I.; Chou, S. H.; Yuan, H.
2014-07-01
A general phenomenological model is presented for obtaining the zero Kelvin work function of any crystal facet of metals and semiconductors, both clean and covered with a monolayer of electropositive atoms. It utilizes the known physical structure of the crystal and the Fermi energy of the two-dimensional electron gas assumed to form on the surface. A key parameter is the number of electrons donated to the surface electron gas per surface lattice site or adsorbed atom, which is taken to be an integer. Initially this is found by trial and later justified by examining the state of the valence electrons of the relevant atoms. In the case of adsorbed monolayers of electropositive atoms a satisfactory justification could not always be found, particularly for cesium, but a trial value always predicted work functions close to the experimental values. The model can also predict the variation of work function with temperature for clean crystal facets. The model is applied to various crystal faces of tungsten, aluminium, silver, and select metal oxides, and most demonstrate good fits compared to available experimental values.
Mathematical Models of Cardiac Pacemaking Function
Directory of Open Access Journals (Sweden)
Pan eLi
2013-10-01
Full Text Available Over the past half century, there has been intense and fruitful interaction between experimental and computational investigations of cardiac function. This interaction has, for example, led to deep understanding of cardiac excitation-contraction coupling; how it works, as well as how it fails. However, many lines of inquiry remain unresolved, among them the initiation of each heartbeat. The sinoatrial node, a cluster of specialized pacemaking cells in the right atrium of the heart, spontaneously generates an electro-chemical wave that spreads through the atria and through the cardiac conduction system to the ventricles, initiating the contraction of cardiac muscle essential for pumping blood to the body. Despite the fundamental importance of this primary pacemaker, this process is still not fully understood, and ionic mechanisms underlying cardiac pacemaking function are currently under heated debate. Several mathematical models of sinoatrial node cell membrane electrophysiology have been constructed as based on different experimental data sets and hypotheses. As could be expected, these differing models offer diverse predictions about cardiac pacemaking activities. This paper aims to present the current state of debate over the origins of the pacemaking function of the sinoatrial node. Here, we will specifically review the state-of-the-art of cardiac pacemaker modeling, with a special emphasis on current discrepancies, limitations, and future challenges.
Directory of Open Access Journals (Sweden)
Maogui Hu
Full Text Available BACKGROUND: Over the past two decades, major epidemics of hand, foot, and mouth disease (HFMD have occurred throughout most of the West-Pacific Region countries, causing thousands of deaths among children. However, few studies have examined potential determinants of the incidence of HFMD. METHODS: Reported HFMD cases from 2912 counties in China were obtained for May 2008. The monthly HFMD cumulative incidence was calculated for children aged 9 years and younger. Child population density (CPD and six climate factors (average-temperature [AT], average-minimum-temperature [AT(min], average-maximum-temperature [AT(max], average-temperature-difference [AT(diff], average-relative-humidity [ARH], and monthly precipitation [MP] were selected as potential explanatory variables for the study. Geographically weighted regression (GWR models were used to explore the associations between the selected factors and HFMD incidence at county level. RESULTS: There were 176,111 HFMD cases reported in the studied counties. The adjusted monthly cumulative incidence by county ranged from 0.26 cases per 100,000 children to 2549.00 per 100,000 children. For local univariate GWR models, the percentage of counties with statistical significance (p<0.05 between HFMD incidence and each of the seven factors were: CPD 84.3%, AT(max 54.9%, AT 57.8%, AT(min 61.2%, ARH 54.4%, MP 50.3%, and AT(diff 51.6%. The R(2 for the seven factors' univariate GWR models are CPD 0.56, AT(max 0.53, AT 0.52, MP 0.51, AT(min 0.52, ARH 0.51, and AT(diff 0.51, respectively. CPD, MP, AT, ARH and AT(diff were further included in the multivariate GWR model, with R(2 0.62, and all counties show statistically significant relationship. CONCLUSION: Child population density and climate factors are potential determinants of the HFMD incidence in most areas in China. The strength and direction of association between these factors and the incidence of HFDM is spatially heterogeneous at the local geographic
[Functional model of the middle ear ossicles].
Satoda, Takahiro; Shimoe, Saiji; Makihira, Seicho; Tamamoto, Mitsuhiro; Matsumoto, Atsue; Hara, Kumiko; Noso, Maki; Niitani, Yoshie; Sugiyama, Masaru; Takemoto, Toshinobu; Murayama, Takeshi; Amano, Hideaki; Nikawa, Hiroki
2009-06-01
In students' dissection practice, it is very difficult to teach students the structures and functions of the middle ear ossicles. The middle ear ossicles are too small to explain their structures and functions. Models are useful in explaining these points, but there have been no models that accurately explain the movements of the middle ear ossicles and the functions of the muscles in the middle ear. This time, we have made a model of middle ear ossicles. Our ear ossicles are made of paper-mache with metal in it. The incudomalleolar and incudostapedial articulations are made of rubber. The tensor tympani and the stapedius muscles are made of wire and the two wires can be fixed by cord stoppers. Our model explains clearly the following mechanisms of the middle ear ossicles. 1. The mechanism of sound conduction system. When the sound vibrates the tympanic membrane, malleus and incus rotate together. The long process of the incus pushes the head of the stapes. The sound is amplified by leverage. 2. Attenuation of sound by contractions of tensor tympani and stapedius muscles. When a loud sound is transmitted through the ossicular system, the tensor tympani muscle pulls the malleus inward while the stapedius muscle pulls the stapes outward. These two forces oppose each other and increase rigidity of the ossicular system, thus reducing the ossicular conduction. 3. The mechanism of how paralysis of stapedius muscle, caused by an injury to the facial nerve, results in hyperacusis. 4. This model also suggests a possible reason why the pars lucida of the tympanic membrane exists.
Marchioro, C A; Foerster, L A
2012-08-01
Temperature is considered to be an important abiotic factor influencing insect reproduction. Despite the importance of Plutella xylostella L. (Lepidoptera: Plutellidae) as a pest of brassicaceous crops worldwide, the effects of temperature on its reproduction are not well understood. We evaluated the effect of constant temperatures ranging from 10 to 32.5°C on the reproduction of P. xylostella and developed an oviposition model for the species. The model combined temperature-dependent parameters of total fecundity, age-specific oviposition rate and age-specific survival. Additionally, we modelled population growth as a function of temperature. The estimated parameters allowed us to discuss the possible consequences of global warming on P. xylostella distribution. Temperature affected the length of pre-oviposition after adult emergence, oviposition period, longevity, total fecundity and egg viability. The model predicted that both daily egg production and length of oviposition period decreased at temperatures below 15°C and above 25°C. Population growth increased linearly with temperature in a range from 10°C to 25°C; however, the model predicted a reduction in population growth at temperatures above 28.6°C. Data suggested that temperature plays a critical role in P. xylostella reproduction, and subtle differences in average temperature could have an impact on its population growth. This is especially important in the context of global climate change, which in turn could alter the distribution and abundance of the pest in some regions of the world.
Garcia, Grant H; Wu, Hao-Hua; Park, Min Jung; Tjoumakaris, Fotios P; Tucker, Bradford S; Kelly, John D; Sennett, Brian J
2016-03-01
Recent literature has recognized a correlation with depression and poor self-reported functional outcome after orthopaedic procedures. However, the effect of depression on anterior cruciate ligament reconstruction (ACLR) outcome has never been studied. To quantify the incidence of major depressive disorder (MDD) and correlate depression symptoms with patient-rated knee function in patients undergoing ACLR. Cohort study; Level of evidence, 2. In this multicenter prospective cohort study, 64 consecutive adult patients undergoing primary ACLR were given the 16-item self-report Quick Inventory of Depressive Symptomatology (QIDS) to assess MDD symptoms preoperatively and at 6 weeks, 12 weeks, 24 weeks, and 1 year postoperatively. Lysholm and International Knee Documentation Committee (IKDC) subjective scores were obtained at the same time points to assess self-reported knee function. A QIDS score ≥6 served as a validated threshold for diagnosis of MDD. MDD and non-MDD group assignment was based on preoperative QIDS score. Student t test analysis was performed to compare ACLR outcomes between MDD and non-MDD patients. Correlation among QIDS, Lysholm, and IKDC scores was determined with Spearman r value. A total of 27 patients (42%) were categorized in the MDD group. At baseline, the MDD group reported mean Lysholm (50.8) and IKDC (43.7) scores that were significantly lower than those (64.9 and 57.0, respectively) reported by the non-MDD group (P < .05). Both cohorts showed similar and significant absolute improvement from baseline to 1 year postoperatively (MDD vs non-MDD, increase in mean Lysholm: +24.4 vs +23.5 [P = .63]; MDD vs non-MDD, increase in mean IKDC: +28.1 vs +32.3 [P = .21]). While Lysholm and IKDC scores improved in both groups, at 1-year follow-up, MDD patients reported significantly lower mean Lysholm (75.2 vs 88.4; P = .04) and mean IKDC (71.8 vs 89.3; P = .001) scores as compared with their non-MDD counterparts. In addition, a moderate inverse
Lou, Jie; Blevins, Meridith; Ruan, Yuhua; Vermund, Sten H.; Tang, Sanyi; Webb, Glenn F.; Shepherd, Bryan E.; He, Xiong; Lu, Hongyan; Shao, Yiming; Qian, Han-Zhu
2014-01-01
Objective To project the HIV/AIDS epidemics among men who have sex with men (MSM) under different combinations of HIV testing and linkage to care (TLC) interventions including antiretroviral therapy (ART) in Beijing, China. Design Mathematical modeling. Methods Using a mathematical model to fit prevalence estimates from 2000–2010, we projected trends in HIV prevalence and incidence during 2011–2020 under five scenarios: (S1) current intervention levels by averaging 2000–2010 coverage; (S2) in...
International Nuclear Information System (INIS)
Prybutok, V.R.
1995-01-01
Risk associated with power generation must be identified to make intelligent choices between alternate power technologies. Radionuclide air stack emissions for a single coal plant and a single nuclear plant are used to compute the single plant leukemia incidence risk and total industry leukemia incidence risk. Leukemia incidence is the response variable as a function of radionuclide bone dose for the six proposed dose response curves considered. During normal operation a coal plant has higher radionuclide emissions than a nuclear plant and the coal industry has a higher leukaemia incidence risk than the nuclear industry, unless a nuclear accident occurs. Variation of nuclear accident size allows quantification of the impact of accidents on the total industry leukemia incidence risk comparison. The leukemia incidence risk is quantified as the number of accidents of a given size for the nuclear industry leukemia incidence risk to equal the coal industry leukemia incidence risk. The general linear model is used to develop equations that relate the accident frequency required for equal industry risks to the magnitude of the nuclear emission. Exploratory data analysis revealed that the relationship between the natural log of accident number versus the natural log of accident size is linear. (Author)
Functional Modeling for Monitoring of Robotic System
DEFF Research Database (Denmark)
Wu, Haiyan; Bateman, Rikke R.; Zhang, Xinxin
2018-01-01
supervisors or cooperators. In this work, we focus on developing a modeling framework for monitoring robotic system based on means-end analysis and the concept of action phases from action theory. A circular cascaded action phase structure is proposed for building the model of cyclical robotic events......With the expansion of robotic applications in the industrial domain, it is important that the robots can execute their tasks in a safe and reliable way. A monitoring system can be implemented to ensure the detection of abnormal situations of the robots and report the abnormality to their human....... This functional model provide a formal way of decompose robotic tasks and analyze each level of conditions for an action to be executed successfully. It can be used for monitoring robotic systems by checking the preconditions in the action phases and identifying the failure modes. The proposed method...
Saha, Sukanta; Whiteford, Harvey; McGrath, John
2014-04-01
The aim of this study was to model estimates related to (a) the incidence of psychotic disorders and (b) the mortality associated with these disorders based on a large, population-based prevalence study. Data were drawn from the second national survey of adults with psychotic disorders conducted in seven Australian catchment areas during March to December 2010. To generate incidence rate estimates, we identified recent onset cases recruited as part of the prevalence study and then imputed population-based incidence rates using a set of conservative assumptions. Similarly, for mortality rates, we identified individuals who had died after being identified as 'screen-positive' for psychosis, but prior to full clinical assessment. Using a set of conservative assumptions, we then used these estimates to infer population-based mortality rates. Based on our models, we estimated that the incidence rate for psychotic disorders was 28 cases per 100,000 population. The rate estimates were significantly higher in males than females, with an overall male:female ratio of 1.57:1. Incidence rate estimates peaked in the youngest age group (18-24 years). The adjusted mortality rate estimated during the whole period of observation was 12.5 per 1000 persons, with a standardised mortality ratio of 5.5. Using treated prevalence data and observed deaths with appropriate algorithms, we were able to impute incidence and mortality rates for psychotic disorders consistent with the published literature. While the second national survey of psychotic disorders was not designed to identify mortality, our estimates provide a stark reminder of the increased mortality associated with these disorders.
Mansori, Kamyar; Solaymani-Dodaran, Masoud; Mosavi-Jarrahi, Alireza; Motlagh, Ali Ganbary; Salehi, Masoud; Delavari, Alireza; Asadi-Lari, Mohsen
2018-01-01
The aim of this study was to determine the factors associated with the spatial distribution of the incidence of colorectal cancer (CRC) in the neighborhoods of Tehran, Iran using Bayesian spatial models. This ecological study was implemented in Tehran on the neighborhood level. Socioeconomic variables, risk factors, and health costs were extracted from the Equity Assessment Study conducted in Tehran. The data on CRC incidence were extracted from the Iranian population-based cancer registry. The Besag-York-Mollié (BYM) model was used to identify factors associated with the spatial distribution of CRC incidence. The software programs OpenBUGS version 3.2.3, ArcGIS 10.3, and GeoDa were used for the analysis. The Moran index was statistically significant for all the variables studied (p<0.05). The BYM model showed that having a women head of household (median standardized incidence ratio [SIR], 1.63; 95% confidence interval [CI], 1.06 to 2.53), living in a rental house (median SIR, 0.82; 95% CI, 0.71 to 0.96), not consuming milk daily (median SIR, 0.71; 95% CI, 0.55 to 0.94) and having greater household health expenditures (median SIR, 1.34; 95% CI, 1.06 to 1.68) were associated with a statistically significant elevation in the SIR of CRC. The median (interquartile range) and mean (standard deviation) values of the SIR of CRC, with the inclusion of all the variables studied in the model, were 0.57 (1.01) and 1.05 (1.31), respectively. Inequality was found in the spatial distribution of CRC incidence in Tehran on the neighborhood level. Paying attention to this inequality and the factors associated with it may be useful for resource allocation and developing preventive strategies in atrisk areas.
Directory of Open Access Journals (Sweden)
Kamyar Mansori
2018-01-01
Full Text Available Objectives The aim of this study was to determine the factors associated with the spatial distribution of the incidence of colorectal cancer (CRC in the neighborhoods of Tehran, Iran using Bayesian spatial models. Methods This ecological study was implemented in Tehran on the neighborhood level. Socioeconomic variables, risk factors, and health costs were extracted from the Equity Assessment Study conducted in Tehran. The data on CRC incidence were extracted from the Iranian population-based cancer registry. The Besag-York-Mollié (BYM model was used to identify factors associated with the spatial distribution of CRC incidence. The software programs OpenBUGS version 3.2.3, ArcGIS 10.3, and GeoDa were used for the analysis. Results The Moran index was statistically significant for all the variables studied (p<0.05. The BYM model showed that having a women head of household (median standardized incidence ratio [SIR], 1.63; 95% confidence interval [CI], 1.06 to 2.53, living in a rental house (median SIR, 0.82; 95% CI, 0.71 to 0.96, not consuming milk daily (median SIR, 0.71; 95% CI, 0.55 to 0.94 and having greater household health expenditures (median SIR, 1.34; 95% CI, 1.06 to 1.68 were associated with a statistically significant elevation in the SIR of CRC. The median (interquartile range and mean (standard deviation values of the SIR of CRC, with the inclusion of all the variables studied in the model, were 0.57 (1.01 and 1.05 (1.31, respectively. Conclusions Inequality was found in the spatial distribution of CRC incidence in Tehran on the neighborhood level. Paying attention to this inequality and the factors associated with it may be useful for resource allocation and developing preventive strategies in atrisk areas.
Hunault, C. C.; Boerleider, R. Z.; Hof, B. G H; Kliest, J. J G; Meijer, M.; Nijhuis, N. J.; De Vries, I.; Meulenbelt, J.
2014-01-01
Context. Acute chemical incidents can have substantial public health consequences in terms of morbidity and mortality. Objective. We aimed to characterize acute chemical incidents and near-misses in the Netherlands and compare the results with previous studies. This review is a first step in
Functionalized anatomical models for EM-neuron Interaction modeling
Neufeld, Esra; Cassará, Antonino Mario; Montanaro, Hazael; Kuster, Niels; Kainz, Wolfgang
2016-06-01
The understanding of interactions between electromagnetic (EM) fields and nerves are crucial in contexts ranging from therapeutic neurostimulation to low frequency EM exposure safety. To properly consider the impact of in vivo induced field inhomogeneity on non-linear neuronal dynamics, coupled EM-neuronal dynamics modeling is required. For that purpose, novel functionalized computable human phantoms have been developed. Their implementation and the systematic verification of the integrated anisotropic quasi-static EM solver and neuronal dynamics modeling functionality, based on the method of manufactured solutions and numerical reference data, is described. Electric and magnetic stimulation of the ulnar and sciatic nerve were modeled to help understanding a range of controversial issues related to the magnitude and optimal determination of strength-duration (SD) time constants. The results indicate the importance of considering the stimulation-specific inhomogeneous field distributions (especially at tissue interfaces), realistic models of non-linear neuronal dynamics, very short pulses, and suitable SD extrapolation models. These results and the functionalized computable phantom will influence and support the development of safe and effective neuroprosthetic devices and novel electroceuticals. Furthermore they will assist the evaluation of existing low frequency exposure standards for the entire population under all exposure conditions.
Directory of Open Access Journals (Sweden)
Oilson Alberto Gonzatto Junior
2017-06-01
Full Text Available Data with excess zeros are frequently found in practice, and the recommended analysis is to use models that adequately address the counting of zero observations. In this study, the Zero Inflated Beta Regression Model (BeZI was used on experimental data to describe the mean incidence of leaf citrus canker in orange groves under the influence of genotype and rootstocks of origin. Based on the model, it was possible to quantify the odds that a null observation to mean incidence comes from a particular plant according to genotype and rootstock, and estimate its expected value according to this combination. Laranja Caipira rootstock proved to be the most resistant to leaf citrus canker as well as Limão Cravo proved to be the most fragile. The Ipiguá IAC, Arapongas, EEL and Olímpia genotypes have statistically equivalent chances.
Functional RG approach to the Potts model
Ben Alì Zinati, Riccardo; Codello, Alessandro
2018-01-01
The critical behavior of the (n+1) -states Potts model in d-dimensions is studied with functional renormalization group techniques. We devise a general method to derive β-functions for continuous values of d and n and we write the flow equation for the effective potential (LPA’) when instead n is fixed. We calculate several critical exponents, which are found to be in good agreement with Monte Carlo simulations and ɛ-expansion results available in the literature. In particular, we focus on Percolation (n\\to0) and Spanning Forest (n\\to-1) which are the only non-trivial universality classes in d = 4,5 and where our methods converge faster.
Main pumps lost incident in the nuclear power plant Atucha I. Modelling with RELAP5/MOD3.2
International Nuclear Information System (INIS)
Ventura, M.A.; Rosso, R.D.
1998-01-01
Time evolution of natural circulation in the nuclear power plant Atucha I (CNA-I), in a main pumps lost incident because of the lost of external power feed, is analyzed. It leads to a strong stop transient, without an important blow down, from a forced nominal flow to a natural circulation one. The results are obtained from RELAP5/MOD3.2 code's modeling. The study is based on the refrigeration conditions analysis, during the first minutes of the reactor out of service. Previously to the transient, work had been done to obtain the plant steady state, with design parameters in operation conditions at 100 % of power. The object is that the actual plant state would be represented. In this way, each plant part (steam generators, reactor, pressurizer, pumps) had been modeled in separated form with the appropriate boundary conditions, to be used in the whole circuit simulation. The developed model, had been validated making use of the comparison between the values obtained to the principal thermodynamic parameters with the plant recorded values, in the same incident. The results are satisfactory in a way. On the other hand, it has suggested some modeling changes. The RELAP5/MOD3.2 capability to model the thermodynamic phenomena in a PHWR plant has been verified when, according to the mentioned incident, the flow pass from a nominal forced flow, to one which is governed by natural circulation, still with the CNA-I untypical design conditions. (author) [es
Development of a model for recording and evaluating incidents in radiotherapy
International Nuclear Information System (INIS)
Ribeiro, A.L.C.; Paiva, E. de; Teixeira, F.C.S.
2017-01-01
Radiotherapy has been constantly improving to become increasingly effective, thus contributing to increase the chances of healing patients. In this sense, incident learning gained prominence during successive approaches to patient safety. The objective is to develop a tool for recording and analyzing incidents in radiotherapy and applying it to clinics in Rio de Janeiro in order to implement the policy of quality management and safety culture. Steps were taken that involved the analysis of the process maps for the enrichment of the system (called the Standardized System of Incidents in Radiotherapy - SPIRad) that already has a version in physical form. The proposal is the conversion of this form to a digital tool to be used through the intranet. The next step is to apply it to radiotherapy clinics in Rio de Janeiro and evaluate the results obtained with the objective of possible improvements through feedback from users
Directory of Open Access Journals (Sweden)
Ashraf T Soliman
2013-01-01
was found between ferritin and TSH. Conclusions: Worsening of thyroid function was observed in 35% of the studied thalassemic patients by the age of 18 years. The lack of proper increase of TSH in response to the low circulating levels of FT4 in 13/17 (76% of these patients indicates a relatively high incidence of defective pituitary thyrotrophic function in these patients.
Electricity price forecasting through transfer function models
International Nuclear Information System (INIS)
Nogales, F.J.; Conejo, A.J.
2006-01-01
Forecasting electricity prices in present day competitive electricity markets is a must for both producers and consumers because both need price estimates to develop their respective market bidding strategies. This paper proposes a transfer function model to predict electricity prices based on both past electricity prices and demands, and discuss the rationale to build it. The importance of electricity demand information is assessed. Appropriate metrics to appraise prediction quality are identified and used. Realistic and extensive simulations based on data from the PJM Interconnection for year 2003 are conducted. The proposed model is compared with naive and other techniques. Journal of the Operational Research Society (2006) 57, 350-356.doi:10.1057/palgrave.jors.2601995; published online 18 May 2005. (author)
Kim, Sun Bean; Yoon, Myoungho; Ku, Nam Su; Kim, Min Hyung; Song, Je Eun; Ahn, Jin Young; Jeong, Su Jin; Kim, Changsoo; Kwon, Hee-Dae; Lee, Jeehyun; Smith, Davey M; Choi, Jun Yong
2014-01-01
Multiple prevention measures have the possibility of impacting HIV incidence in South Korea, including early diagnosis, early treatment, and pre-exposure prophylaxis (PrEP). We investigated how each of these interventions could impact the local HIV epidemic, especially among men who have sex with men (MSM), who have become the major risk group in South Korea. A mathematical model was used to estimate the effects of each these interventions on the HIV epidemic in South Korea over the next 40 years, as compared to the current situation. We constructed a mathematical model of HIV infection among MSM in South Korea, dividing the MSM population into seven groups, and simulated the effects of early antiretroviral therapy (ART), early diagnosis, PrEP, and combination interventions on the incidence and prevalence of HIV infection, as compared to the current situation that would be expected without any new prevention measures. Overall, the model suggested that the most effective prevention measure would be PrEP. Even though PrEP effectiveness could be lessened by increased unsafe sex behavior, PrEP use was still more beneficial than the current situation. In the model, early diagnosis of HIV infection was also effectively decreased HIV incidence. However, early ART did not show considerable effectiveness. As expected, it would be most effective if all interventions (PrEP, early diagnosis and early treatment) were implemented together. This model suggests that PrEP and early diagnosis could be a very effective way to reduce HIV incidence in South Korea among MSM.
Reconstruction of an incident using video images and 3D models
Iersel, M. van; Bijhold, J.; Edelman, G.
2008-01-01
The growing amount of security cameras increases the chance that there is important video footage available for the reconstruction of an incident. Using the right methods for analysis of large amounts of videos, it is possible to use this relevant information. In collaboration with the Netherlands
76 FR 17022 - Special Conditions: Gulfstream Model GVI Airplane; High Incidence Protection
2011-03-28
... attack that can be attained to a value below that at which an aerodynamic stall would occur. (c) Alpha... stall speed, not more than zero thrust at the stall speed. (2) The airplane in other respects (such as...). However, reasonable attitude changes associated with stabilizing the incidence at alpha limit as the...
75 FR 80735 - Special Conditions: Gulfstream Model GVI Airplane; High Incidence Protection
2010-12-23
... which an aerodynamic stall would occur. (c) Alpha-Limit--The maximum angle of attack at which the... decrease in stall speed, not more than zero thrust at the stall speed. (2) The airplane in other respects... the incidence at alpha limit as the longitudinal control reaches the stop is acceptable. Any reduction...
Energy Technology Data Exchange (ETDEWEB)
Steiner, Martin; Karcher, Klaus; Nosske, Dietmar [Bundesamt fuer Strahlenschutz, Oberschleissheim (Germany)
2012-06-15
The radiation exposure after a short-term release of radioactive substances is often calculated assuming equilibrium conditions. An example is that of the German Incident Calculation Bases for nuclear power plants with pressurized water reactors. Here, the contamination of human milk is calculated using transfer factors. Applying this equilibrium model to incident situations raises the question whether baby's radiation exposure is adequately assessed. This contribution shows that compliance with the relevant dose limits of paragraph 49 of the German Radiation Protection Ordinance is ensured for design basis accidents on the assumption that the hypothetical breastfeeding period starts at the beginning of the activity release. Comparative analyses were performed against the biokinetic models applied by ICRP for radiation protection purposes, taking the reference nuclides {sup 137}Cs, {sup 90}Sr, {sup 131}I, {sup 241}Am and long-lived plutonium isotopes as examples. (orig.)
Miao, Hui; Teng, Zhidong; Li, Zhiming
2016-01-01
The dynamical behaviors for a five-dimensional viral infection model with three delays which describes the interactions of antibody, cytotoxic T-lymphocyte (CTL) immune responses, and nonlinear incidence rate are investigated. The threshold values for viral infection, antibody response, CTL immune response, CTL immune competition, and antibody competition, respectively, are established. Under certain assumptions, the threshold value conditions on the global stability of the infection-free, im...
Mousam, Aneela; Maggioni, Viviana; Delamater, Paul L.; Quispe, Antonio M.
2017-10-01
Between 2001 and 2010 significant progress was made towards reducing the number of malaria cases in Peru; however, the country saw an increase between 2011 and 2015. This work attempts to uncover the associations among various climatic and environmental variables and the annual malaria parasite incidence in the Peruvian region of Loreto. A Multilevel Mixed-effects Poisson Regression model is employed, focusing on the 2009-2013 period, when trends in malaria incidence shifted from decreasing to increasing. The results indicate that variations in elevation (β = 0.78; 95% confidence interval (CI), 0.75-0.81), soil moisture (β = 0.0021; 95% CI, 0.0019-0.0022), rainfall (β = 0.59; 95% CI, 0.56-0.61), and normalized difference vegetation index (β = 2.13; 95% CI, 1.83-2.43) is associated with higher annual parasite incidence, whereas an increase in temperature (β = -0.0043; 95% CI, - 0.0044- 0.0041) is associated with a lower annual parasite incidence. The results from this study are particularly useful for healthcare workers in Loreto and have the potential of being integrated within malaria elimination plans.
A Prediction Model of the Capillary Pressure J-Function.
Directory of Open Access Journals (Sweden)
W S Xu
Full Text Available The capillary pressure J-function is a dimensionless measure of the capillary pressure of a fluid in a porous medium. The function was derived based on a capillary bundle model. However, the dependence of the J-function on the saturation Sw is not well understood. A prediction model for it is presented based on capillary pressure model, and the J-function prediction model is a power function instead of an exponential or polynomial function. Relative permeability is calculated with the J-function prediction model, resulting in an easier calculation and results that are more representative.
Imaging radiation pneumonitis in a rat model of a radiological terrorism incident
Molthen, Robert; Wu, QingPing; Krenz, Gary; Medhora, Meetha; Jacobs, Elizabeth; Moulder, John E.
2009-02-01
We have developed a rat model of single, sub-lethal thoracic irradiation. Our irradiation protocol is considered representative of exposures near the detonation site of a dirty bomb or small nuclear device. The model is being used to investigate techniques for identifying, triaging and treating possible victims. In addition to physiological markers of right ventricular hypertrophy, pulmonary vascular resistance, and arterial distensibility, we present two methods for quantifying microvascular density. We used methods including microfocal X-ray imaging to investigate changes in lung structure/function resulting from radiation exposure. Radiation pneumonitis is a complication in subjects receiving thoracic irradiation. A radiographic hallmark of acute radiation pneumonitis is a diffuse infiltrate corresponding to the radiation treatment field. We describe two methods for quantifying small artery dropout that occurs in the model at the same time-period. Rats were examined 3-days, 2-weeks, 1-month (m), 2-m, 5-m, and 12-m post-irradiation and compared with aged-matched controls. Right ventricular hypertrophy and increases in pulmonary vascular resistance were present during the pneumonitis phase. Vascular injury was dependent on dose and post-irradiation duration. Rats irradiated with 5 Gy had few detectable changes, whereas 10 Gy resulted in a significant decrease in both microvascular density and arterial distensibility around 2- m, the decrease in each lessening, but extending through 12-m. In conclusion, rats irradiated with a 10 Gy dose had changes in vascular structure concurrent with the onset of radiation pneumonitis that were detectable with our imaging techniques and these structural changes persist after resolution of the pneumonitis.
Functional methods in the generalized Dicke model
International Nuclear Information System (INIS)
Alcalde, M. Aparicio; Lemos, A.L.L. de; Svaiter, N.F.
2007-01-01
The Dicke model describes an ensemble of N identical two-level atoms (qubits) coupled to a single quantized mode of a bosonic field. The fermion Dicke model should be obtained by changing the atomic pseudo-spin operators by a linear combination of Fermi operators. The generalized fermion Dicke model is defined introducing different coupling constants between the single mode of the bosonic field and the reservoir, g 1 and g 2 for rotating and counter-rotating terms respectively. In the limit N -> ∞, the thermodynamic of the fermion Dicke model can be analyzed using the path integral approach with functional method. The system exhibits a second order phase transition from normal to superradiance at some critical temperature with the presence of a condensate. We evaluate the critical transition temperature and present the spectrum of the collective bosonic excitations for the general case (g 1 ≠ 0 and g 2 ≠ 0). There is quantum critical behavior when the coupling constants g 1 and g 2 satisfy g 1 + g 2 =(ω 0 Ω) 1/2 , where ω 0 is the frequency of the mode of the field and Ω is the energy gap between energy eigenstates of the qubits. Two particular situations are analyzed. First, we present the spectrum of the collective bosonic excitations, in the case g 1 ≠ 0 and g 2 ≠ 0, recovering the well known results. Second, the case g 1 ≠ 0 and g 2 ≠ 0 is studied. In this last case, it is possible to have a super radiant phase when only virtual processes are introduced in the interaction Hamiltonian. Here also appears a quantum phase transition at the critical coupling g 2 (ω 0 Ω) 1/2 , and for larger values for the critical coupling, the system enter in this super radiant phase with a Goldstone mode. (author)
Directory of Open Access Journals (Sweden)
Ujué Fresán
2016-10-01
Full Text Available Obesity is a major epidemic for developed countries in the 21st century. The main cause of obesity is energy imbalance, of which contributing factors include a sedentary lifestyle, epigenetic factors and excessive caloric intake through food and beverages. A high consumption of caloric beverages, such as alcoholic or sweetened drinks, may particularly contribute to weight gain, and lower satiety has been associated with the intake of liquid instead of solid calories. Our objective was to evaluate the association between the substitution of a serving per day of water for another beverage (or group of them and the incidence of obesity and weight change in a Mediterranean cohort, using mathematical models. We followed 15,765 adults without obesity at baseline. The intake of 17 beverage items was assessed at baseline through a validated food-frequency questionnaire. The outcomes were average change in body weight in a four-year period and new-onset obesity and their association with the substitution of one serving per day of water for one of the other beverages. During the follow-up, 873 incident cases of obesity were identified. In substitution models, the consumption of water instead of beer or sugar-sweetened soda beverages was associated with a lower obesity incidence (the Odds Ratio (OR 0.80 (95% confidence interval (CI 0.68 to 0.94 and OR 0.85 (95% CI 0.75 to 0.97; respectively and, in the case of beer, it was also associated with a higher average weight loss (weight change difference = −328 g; (95% CI −566 to −89. Thus, this study found that replacing one sugar-sweetened soda beverage or beer with one serving of water per day at baseline was related to a lower incidence of obesity and to a higher weight loss over a four-year period time in the case of beer, based on mathematical models.
Lee, Tsair-Fwu; Chao, Pei-Ju; Chang, Liyun; Ting, Hui-Min; Huang, Yu-Jie
2015-01-01
Symptomatic radiation pneumonitis (SRP), which decreases quality of life (QoL), is the most common pulmonary complication in patients receiving breast irradiation. If it occurs, acute SRP usually develops 4-12 weeks after completion of radiotherapy and presents as a dry cough, dyspnea and low-grade fever. If the incidence of SRP is reduced, not only the QoL but also the compliance of breast cancer patients may be improved. Therefore, we investigated the incidence SRP in breast cancer patients after hybrid intensity modulated radiotherapy (IMRT) to find the risk factors, which may have important effects on the risk of radiation-induced complications. In total, 93 patients with breast cancer were evaluated. The final endpoint for acute SRP was defined as those who had density changes together with symptoms, as measured using computed tomography. The risk factors for a multivariate normal tissue complication probability model of SRP were determined using the least absolute shrinkage and selection operator (LASSO) technique. Five risk factors were selected using LASSO: the percentage of the ipsilateral lung volume that received more than 20-Gy (IV20), energy, age, body mass index (BMI) and T stage. Positive associations were demonstrated among the incidence of SRP, IV20, and patient age. Energy, BMI and T stage showed a negative association with the incidence of SRP. Our analyses indicate that the risk of SPR following hybrid IMRT in elderly or low-BMI breast cancer patients is increased once the percentage of the ipsilateral lung volume receiving more than 20-Gy is controlled below a limitation. We suggest to define a dose-volume percentage constraint of IV20radiation therapy treatment planning to maintain the incidence of SPR below 20%, and pay attention to the sequelae especially in elderly or low-BMI breast cancer patients. (AIV20: the absolute ipsilateral lung volume that received more than 20 Gy (cc).
Improved parameter estimation for hydrological models using weighted object functions
Stein, A.; Zaadnoordijk, W.J.
1999-01-01
This paper discusses the sensitivity of calibration of hydrological model parameters to different objective functions. Several functions are defined with weights depending upon the hydrological background. These are compared with an objective function based upon kriging. Calibration is applied to
Directory of Open Access Journals (Sweden)
Hernan A. Moreno
2018-03-01
Full Text Available This article presents a methodology for estimating total incoming solar radiation from Triangular Irregular Network (TIN topographic meshes. The algorithm also computes terrain slope degree and aspect (slope orientation and accounts for self shading and cast shadows, sky view fractions for diffuse radiation, remote albedo and atmospheric backscattering, by using a vectorial approach within a topocentric coordinate system establishing geometric relations between groups of TIN elements and the sun position. A normal vector to the surface of each TIN element describes its slope and aspect while spherical trigonometry allows computing a unit vector defining the position of the sun at each hour and day of the year. Sky view fraction, useful to determine diffuse and backscattered radiation, is computed for each TIN element at prescribed azimuth intervals targeting the steepest elevation gradient. A comparison between the sun zenith angle and the steepest gradient allows deciding whether or not the pivot element is shaded. Finally, remote albedo is computed from the sky view fraction complementary functions for observed albedo values of the surrounding terrain. The sensitivity of the different radiative components to seasonal changes in atmospheric transmissivitties and surrounding albedo is tested in a mountainous watershed in Wyoming. This methodology represents an improvement on the current algorithms to compute terrain and radiation values on unstructured-mesh terrain models. All terrain-related features (e.g., slope, aspect, sky view fraction can be pre-computed and stored for easy access into a subsequent, progressive-in-time, numerical simulation.
Silencing of the rotavirus NSP4 protein decreases the incidence of biliary atresia in murine model.
Directory of Open Access Journals (Sweden)
Jiexiong Feng
Full Text Available Biliary atresia is a common disease in neonates which causes obstructive jaundice and progressive hepatic fibrosis. Our previous studies indicate that rotavirus infection is an initiator in the pathogenesis of experimental biliary atresia (BA through the induction of increased nuclear factor-kappaB and abnormal activation of the osteopontin inflammation pathway. In the setting of rotavirus infection, rotavirus nonstructural protein 4 (NSP4 serves as an important immunogen, viral protein 7 (VP7 is necessary in rotavirus maturity and viral protein 4 (VP4 is a virulence determiner. The purpose of the current study is to clarify the roles of NSP4, VP7 and VP4 in the pathogenesis of experimental BA. Primary cultured extrahepatic biliary epithelia were infected with Rotavirus (mmu18006. Small interfering RNA targeting NSP4, VP7 or VP4 was transfected before rotavirus infection both in vitro and in vivo. We analyzed the incidence of BA, morphological change, morphogenesis of viral particles and viral mRNA and protein expression. The in vitro experiments showed NSP4 silencing decreased the levels of VP7 and VP4, reduced viral particles and decreased cytopathic effect. NSP4-positive cells had strongly positive expression of integrin subunit α2. Silencing of VP7 or VP4 partially decreased epithelial injury. Animal experiments indicated after NSP4 silencing, mouse pups had lower incidence of BA than after VP7 or VP4 silencing. However, 33.3% of VP4-silenced pups (N = 6 suffered BA and 50% of pups (N = 6 suffered biliary injury after VP7 silencing. Hepatic injury was decreased after NSP4 or VP4 silencing. Neither VP4 nor VP7 were detected in the biliary ducts after NSP4. All together, NSP4 silencing down-regulates VP7 and VP4, resulting in decreased incidence of BA.
Function modeling: improved raster analysis through delayed reading and function raster datasets
John S. Hogland; Nathaniel M. Anderson; J .Greg Jones
2013-01-01
Raster modeling is an integral component of spatial analysis. However, conventional raster modeling techniques can require a substantial amount of processing time and storage space, often limiting the types of analyses that can be performed. To address this issue, we have developed Function Modeling. Function Modeling is a new modeling framework that streamlines the...
Souliès, Antoine; Legrand, Jack; Marec, Hélène; Pruvost, Jérémy; Castelain, Cathy; Burghelea, Teodor; Cornet, Jean-François
2016-03-01
An in-depth investigation of how various illumination conditions influence microalgal growth in photobioreactors (PBR) has been presented. Effects of both the light emission spectrum (white and red) and the light incident angle (0° and 60°) on the PBR surface were investigated. The experiments were conducted in two fully controlled lab-scale PBRs, a torus PBR and a thin flat-panel PBR for high cell density culture. The results obtained in the torus PBR were used to build the kinetic growth model of Chlorella vulgaris taken as a model species. The PBR model was then applied to the thin flat-panel PBR, which was run with various illumination conditions. Its detailed representation of local rate of photon absorption under various conditions (spectral calculation of light attenuation, incident angle influence) enabled the model to take into account all the tested conditions with no further adjustment. This allowed a detailed investigation of the coupling between radiation field and photosynthetic growth. Effects of all the radiation conditions together with pigment acclimation, which was found to be relevant, were investigated in depth. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:247-261, 2016. © 2016 American Institute of Chemical Engineers.
Ferroli, Paolo; Caldiroli, Dario; Acerbi, Francesco; Scholtze, Maurizio; Piro, Alfonso; Schiariti, Marco; Orena, Eleonora F; Castiglione, Melina; Broggi, Morgan; Perin, Alessandro; DiMeco, Francesco
2012-11-01
Incident reporting systems are universally recognized as important tools for quality improvement in all complex adaptive systems, including the operating room. Nevertheless, introducing a safety culture among neurosurgeons is a slow process, and few studies are available in the literature regarding the implementation of an incident reporting system within a neurosurgical department. The authors describe the institution of an aviation model of incident reporting and investigation in neurosurgery, focusing on the method they have used and presenting some preliminary results. In 2010, the Inpatient Safety On-Board project was developed through cooperation between a team of human factor and safety specialists with aviation backgrounds (DgSky team) and the general manager of the Fondazione Istituto Neurologico Carlo Besta. In 2011, after specific training in safety culture, the authors implemented an aviation-derived prototype of incident reporting within the Department of Neurosurgery. They then developed an experimental protocol to track, analyze, and categorize any near misses that happened in the operating room. This project officially started in January 2012, when a dedicated team of assessors was established. All members of the neurosurgical department were asked to report near misses on a voluntary, confidential, and protected form (Patient Incident Reporting System form, Besta Safety Management Programme). Reports were entered into an online database and analyzed by a dedicated team of assessors with the help of a facilitator, and an aviation-derived root cause analysis was performed. Since January 2012, 14 near misses were analyzed and classified. The near-miss contributing factors were mainly related to human factors (9 of 14 cases), technology (1 of 14 cases), organizational factors (3 of 14 cases), or procedural factors (1 of 14 cases). Implementing an incident reporting system is quite demanding; the process should involve all of the people who work within
Kozhevnikov, I. V.; Buzmakov, A. V.; Siewert, F.; Tiedtke, K.; Störmer, M.; Samoylova, L.; Sinn, H.
2017-05-01
Simple analytic equation is deduced to explain new physical phenomenon detected experimentally: growth of nano-dots (40-55 nm diameter, 8-13 nm height, 9.4 dots/μm2 surface density) on the grazing incidence mirror surface under the three years irradiation by the free electron laser FLASH (5-45 nm wavelength, 3 degrees grazing incidence angle). The growth model is based on the assumption that the growth of nano-dots is caused by polymerization of incoming hydrocarbon molecules under the action of incident photons directly or photoelectrons knocked out from a mirror surface. The key feature of our approach consists in that we take into account the radiation intensity variation nearby a mirror surface in an explicit form, because the polymerization probability is proportional to it. We demonstrate that the simple analytic approach allows to explain all phenomena observed in experiment and to predict new effects. In particular, we show that the nano-dots growth depends crucially on the grazing angle of incoming beam and its intensity: growth of nano-dots is observed in the limited from above and below intervals of the grazing angle and the radiation intensity. Decrease in the grazing angle by 1 degree only (from 3 to 2 degree) may result in a strong suppression of nanodots growth and their total disappearing. Similarly, decrease in the radiation intensity by several times (replacement of free electron laser by synchrotron) results also in disappearing of nano-dots growth.
Van Eck, D.
2009-01-01
In this paper, I discuss a methodology for the conversion of functional models between functional taxonomies developed by Kitamura et al. (2007) and Ookubo et al. (2007). They apply their methodology to the conversion of functional models described in terms of the Functional Basis taxonomy into
Mirror neurons: functions, mechanisms and models.
Oztop, Erhan; Kawato, Mitsuo; Arbib, Michael A
2013-04-12
Mirror neurons for manipulation fire both when the animal manipulates an object in a specific way and when it sees another animal (or the experimenter) perform an action that is more or less similar. Such neurons were originally found in macaque monkeys, in the ventral premotor cortex, area F5 and later also in the inferior parietal lobule. Recent neuroimaging data indicate that the adult human brain is endowed with a "mirror neuron system," putatively containing mirror neurons and other neurons, for matching the observation and execution of actions. Mirror neurons may serve action recognition in monkeys as well as humans, whereas their putative role in imitation and language may be realized in human but not in monkey. This article shows the important role of computational models in providing sufficient and causal explanations for the observed phenomena involving mirror systems and the learning processes which form them, and underlines the need for additional circuitry to lift up the monkey mirror neuron circuit to sustain the posited cognitive functions attributed to the human mirror neuron system. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
Modeling Bamboo as a Functionally Graded Material
Silva, Emílio Carlos Nelli; Walters, Matthew C.; Paulino, Glaucio H.
2008-02-01
Natural fibers are promising for engineering applications due to their low cost. They are abundantly available in tropical and subtropical regions of the world, and they can be employed as construction materials. Among natural fibers, bamboo has been widely used for housing construction around the world. Bamboo is an optimized composite material which exploits the concept of Functionally Graded Material (FGM). Biological structures, such as bamboo, are composite materials that have complicated shapes and material distribution inside their domain, and thus the use of numerical methods such as the finite element method and multiscale methods such as homogenization, can help to further understanding of the mechanical behavior of these materials. The objective of this work is to explore techniques such as the finite element method and homogenization to investigate the structural behavior of bamboo. The finite element formulation uses graded finite elements to capture the varying material distribution through the bamboo wall. To observe bamboo behavior under applied loads, simulations are conducted considering a spatially-varying Young's modulus, an averaged Young's modulus, and orthotropic constitutive properties obtained from homogenization theory. The homogenization procedure uses effective, axisymmetric properties estimated from the spatially-varying bamboo composite. Three-dimensional models of bamboo cells were built and simulated under tension, torsion, and bending load cases.
Shin, Yung C.; Bailey, Neil; Katinas, Christopher; Tan, Wenda
2018-01-01
This paper presents an overview of vertically integrated comprehensive predictive modeling capabilities for directed energy deposition processes, which have been developed at Purdue University. The overall predictive models consist of vertically integrated several modules, including powder flow model, molten pool model, microstructure prediction model and residual stress model, which can be used for predicting mechanical properties of additively manufactured parts by directed energy deposition processes with blown powder as well as other additive manufacturing processes. Critical governing equations of each model and how various modules are connected are illustrated. Various illustrative results along with corresponding experimental validation results are presented to illustrate the capabilities and fidelity of the models. The good correlations with experimental results prove the integrated models can be used to design the metal additive manufacturing processes and predict the resultant microstructure and mechanical properties.
School Teams up for SSP Functional Models
Pignolet, G.; Lallemand, R.; Celeste, A.; von Muldau, H.
2002-01-01
Space Solar Power systems appear increasingly as one of the major solutions to the upcoming global energy crisis, by collecting solar energy in space where this is most easy, and sending it by microwave beam to the surface of the planet, where the need for controlled energy is located. While fully operational systems are still decades away, the need for major development efforts is with us now. Yet, for many decision-makers and for most of the public, SSP often still sounds like science fiction. Six functional demonstration systems, based on the Japanese SPS-2000 concept, have been built as a result of a cooperation between France and Japan, and they are currently used extensively, in Japan, in Europe and in North America, for executive presentations as well as for public exhibitions. There is demand for more models, both for science museums and for use by energy dedicated groups, and a senior high school in La Reunion, France, has picked up the challenge to make the production of such models an integrated practical school project for pre-college students. In December 2001, the administration and the teachers of the school have evaluated the feasibility of the project and eventually taken the go decision for the school year 2002- 2003, when for education purposes a temporary "school business company" will be incorporated with the goal to study and manufacture a limited series of professional quality SSP demonstration models, and to sell them world- wide to institutions and advocacy groups concerned with energy problems and with the environment. The different sections of the school will act as the different services of an integrated business : based on the current existing models, the electronic section will redesign the energy management system and the microwave projector module, while the mechanical section of the school will adapt and re-conceive the whole packaging of the demonstrator. The French and foreign language sections will write up a technical manual for
Breast cancer risk in atomic bomb survivors from multi-model inference with incidence data 1958-1998
International Nuclear Information System (INIS)
Kaiser, J.C.; Jacob, P.; Meckbach, R.; Cullings, H.M.
2012-01-01
Breast cancer risk from radiation exposure has been analyzed in the cohort of Japanese a-bomb survivors using empirical models and mechanistic two-step clonal expansion (TSCE) models with incidence data from 1958 to 1998. TSCE models rely on a phenomenological representation of cell transition processes on the path to cancer. They describe the data as good as empirical models and this fact has been exploited for risk assessment. Adequate models of both types have been selected with a statistical protocol based on parsimonious parameter deployment and their risk estimates have been combined using multi-model inference techniques. TSCE models relate the radiation risk to cell processes which are controlled by age-increasing rates of initiating mutations and by changes in hormone levels due to menopause. For exposure at young age, they predict an enhanced excess relative risk (ERR) whereas the preferred empirical model shows no dependence on age at exposure. At attained age 70, the multi-model median of the ERR at 1 Gy decreases moderately from 1.2 Gy -1 (90% CI 0.72; 2.1) for exposure at age 25 to a 30% lower value for exposure at age 55. For cohort strata with few cases, where model predictions diverge, uncertainty intervals from multi-model inference are enhanced by up to a factor of 1.6 compared to the preferred empirical model. Multi-model inference provides a joint risk estimate from several plausible models rather than relying on a single model of choice. It produces more reliable point estimates and improves the characterization of uncertainties. The method is recommended for risk assessment in practical radiation protection. (orig.)
Breast cancer risk in atomic bomb survivors from multi-model inference with incidence data 1958-1998
Energy Technology Data Exchange (ETDEWEB)
Kaiser, J.C.; Jacob, P.; Meckbach, R. [Institute of Radiation Protection, Helmholtz-Zentrum Muenchen, German Research Centre for Environmental Health, Neuherberg (Germany); Cullings, H.M. [Radiation Effects Research Foundation, Department of Statistics, Hiroshima (Japan)
2012-03-15
Breast cancer risk from radiation exposure has been analyzed in the cohort of Japanese a-bomb survivors using empirical models and mechanistic two-step clonal expansion (TSCE) models with incidence data from 1958 to 1998. TSCE models rely on a phenomenological representation of cell transition processes on the path to cancer. They describe the data as good as empirical models and this fact has been exploited for risk assessment. Adequate models of both types have been selected with a statistical protocol based on parsimonious parameter deployment and their risk estimates have been combined using multi-model inference techniques. TSCE models relate the radiation risk to cell processes which are controlled by age-increasing rates of initiating mutations and by changes in hormone levels due to menopause. For exposure at young age, they predict an enhanced excess relative risk (ERR) whereas the preferred empirical model shows no dependence on age at exposure. At attained age 70, the multi-model median of the ERR at 1 Gy decreases moderately from 1.2 Gy{sup -1} (90% CI 0.72; 2.1) for exposure at age 25 to a 30% lower value for exposure at age 55. For cohort strata with few cases, where model predictions diverge, uncertainty intervals from multi-model inference are enhanced by up to a factor of 1.6 compared to the preferred empirical model. Multi-model inference provides a joint risk estimate from several plausible models rather than relying on a single model of choice. It produces more reliable point estimates and improves the characterization of uncertainties. The method is recommended for risk assessment in practical radiation protection. (orig.)
[New avenues to quality assurance--a model project for recording bedsore incidence].
Steingass, S; Klein, B; Hube, G; Pavel, K; Walter, K; Weiss, V
2002-11-01
Bedsores can usually be avoided by adequate care and preventive measures. In the context of the local agenda process a local district office (Landratsamt) and inspection units initiated a variety of activities to promote sensitisation in health institutions and contribute to an increase in life quality of the persons concerned. Nearly all nursing care homes, domiciliary services and hospitals participated in a pilot study which was accompanied by the Fraunhofer IAO in Stuttgart. Objectives of the pilot study were to implement internal quality assurance to sensitise for persons the topic and to collect comparable data to achieve benchmarking. Software-tool institutions recorded data on care days, days spent with bedsores according to care level from July till September 01. Major result was that - although institutions had already a decreasing incidence in bedsores since the start of discussing the project - bedsore quotas could be further decreased from 2.15 to 1.84 %.
Field assessment of a model tuberculosis outbreak response plan for low-incidence areas
Directory of Open Access Journals (Sweden)
Pascopella Lisa
2007-10-01
Full Text Available Abstract Background For a regional project in four low-incidence states, we designed a customizable tuberculosis outbreak response plan. Prior to dissemination of the plan, a tuberculosis outbreak occurred, presenting an opportunity to perform a field assessment of the plan. The purpose of the assessment was to ensure that the plan included essential elements to help public health professionals recognize and respond to outbreaks. Methods We designed a semi-structured questionnaire and interviewed all key stakeholders involved in the response. We used common themes to assess validity of and identify gaps in the plan. A subset of participants provided structured feedback on the plan. Results We interviewed 11 public health and six community stakeholders. The assessment demonstrated that (1 almost all of the main response activities were reflected in the plan; (2 the plan added value by providing a definition of a tuberculosis outbreak and guidelines for communication and evaluation. These were areas that lacked written protocols during the actual outbreak response; and (3 basic education about tuberculosis and the interpretation and use of genotyping data were important needs. Stakeholders also suggested adding to the plan questions for evaluation and a section for specific steps to take when an outbreak is suspected. Conclusion An interactive field assessment of a programmatic tool revealed the value of a systematic outbreak response plan with a standard definition of a tuberculosis outbreak, guidelines for communication and evaluation, and response steps. The assessment highlighted the importance of education and training for tuberculosis in low-incidence areas.
Energy Technology Data Exchange (ETDEWEB)
Howard, Michelle, E-mail: Mhoward24601@yahoo.com [University of Wisconsin—La Crosse, WI 54601 (United States)
2013-04-01
ABSTRACT: Burnout and compassion fatigue (CF) adversely affect medical professionals, including those employed in radiation oncology. Previously conducted research acknowledged the presence of burnout in populations of radiation therapists, radiation oncologists, and oncology nursing staff. The aim of the following research was to measure the incidence of burnout or CF in the specific population of medical dosimetrists surveyed. As professional members of the radiation oncology team, this group had not been included in published research data to date. The hypothesis of the subsequent study stated that a comparable incidence of burnout would be observed among medical dosimetrists as had been reported by earlier researchers for a population of radiation therapists. A survey tool based on the Maslach Burnout Inventory (MBI) and distributed to full members of the American Association of Medical Dosimetrists (AAMD) was utilized as the research measurement method. Results obtained indicated an incidence rates of burnout or CF for medical dosimetrists were less than the rates previously measured for radiation therapists (53% vs 11% for emotional exhaustion [EE] and 45% vs 27% for depersonalization [DP]). The incidence of burnout was based on the Burnout Inventory (BI) developed for the research project. Each of the subscales, EE, DP, and decreased personal accomplishment (PA), was considered and analyzed independently. Although not as prevalent among medical dosimetrists as a variety of additional radiation oncology professionals, a significant portion of the population demonstrated signs of burnout or CF. Future concerns abound for the population of medical dosimetrists as a large number of members scored positive for intermediate risk of burnout and CF. Additionally, a large portion of the population was found to be rapidly approaching retirement.
International Nuclear Information System (INIS)
Howard, Michelle
2013-01-01
ABSTRACT: Burnout and compassion fatigue (CF) adversely affect medical professionals, including those employed in radiation oncology. Previously conducted research acknowledged the presence of burnout in populations of radiation therapists, radiation oncologists, and oncology nursing staff. The aim of the following research was to measure the incidence of burnout or CF in the specific population of medical dosimetrists surveyed. As professional members of the radiation oncology team, this group had not been included in published research data to date. The hypothesis of the subsequent study stated that a comparable incidence of burnout would be observed among medical dosimetrists as had been reported by earlier researchers for a population of radiation therapists. A survey tool based on the Maslach Burnout Inventory (MBI) and distributed to full members of the American Association of Medical Dosimetrists (AAMD) was utilized as the research measurement method. Results obtained indicated an incidence rates of burnout or CF for medical dosimetrists were less than the rates previously measured for radiation therapists (53% vs 11% for emotional exhaustion [EE] and 45% vs 27% for depersonalization [DP]). The incidence of burnout was based on the Burnout Inventory (BI) developed for the research project. Each of the subscales, EE, DP, and decreased personal accomplishment (PA), was considered and analyzed independently. Although not as prevalent among medical dosimetrists as a variety of additional radiation oncology professionals, a significant portion of the population demonstrated signs of burnout or CF. Future concerns abound for the population of medical dosimetrists as a large number of members scored positive for intermediate risk of burnout and CF. Additionally, a large portion of the population was found to be rapidly approaching retirement
Energy Technology Data Exchange (ETDEWEB)
Játékos, Balázs, E-mail: jatekosb@eik.bme.hu; Ujhelyi, Ferenc; Lőrincz, Emőke; Erdei, Gábor
2015-01-01
SPADnet-I is a prototype, fully digital, high spatial and temporal resolution silicon photon counter, based on standard CMOS imaging technology, developed by the SPADnet consortium. Being a novel device, the exact dependence of photon detection probability (PDP) of SPADnet-I was not known as a function of angle of incidence, wavelength and polarization of the incident light. Our targeted application area of this sensor is next generation PET detector modules, where they will be used along with LYSO:Ce scintillators. Hence, we performed an extended investigation of PDP in a wide range of angle of incidence (0° to 80°), concentrating onto a 60 nm broad wavelength interval around the characteristic emission peak (λ=420 nm) of the scintillator. In the case where the sensor was optically coupled to a scintillator, our experiments showed a notable dependence of PDP on angle, polarization and wavelength. The sensor has an average PDP of approximately 30% from 0° to 60° angle of incidence, where it starts to drop rapidly. The PDP turned out not to be polarization dependent below 30°. If the sensor is used without a scintillator (i.e. the light source is in air), the polarization dependence is much less expressed, it begins only from 50°.
Directory of Open Access Journals (Sweden)
Maayken Elizabeth Louise van den Berg
2017-01-01
Full Text Available Purpose. Understanding the presentation of spinal cord injury (SCI due to tumours considering population distribution and temporal trends is key to managing SCI health services. This study quantified incidence rates, function scores, and trends of SCI due to tumour or metastasis over an 18-year time period in a defined region in Spain. Methods. A retrospective cohort study included in-and outpatients with nontraumatic SCI due to tumour or metastasis admitted to a metropolitan hospital in Spain between 1991 and 2008. Main outcome measures were crude and age- and sex-adjusted incidence rates, tumour location and type, distribution by spinal level, neurological level of injury, and impairment ASIA scores. Results. Primary tumour or metastasis accounted for 32.5% of nontraumatic SCI with an incidence rate of 4.1 per million population. Increasing rates with age and over time were observed. Major pathology groups were intradural-extramedullary masses from which meningiomas and neurinomas accounted for 40%. Lesions were mostly incomplete with predominant ASIA Grade D. Conclusions. Increasing incidence rates of tumour-related SCI over time in the middle-aged and the elderly suggest a growing need for neurooncology health resources in the future.
Evaluation of predictive models for delayed graft function of deceased kidney transplantation.
Zhang, Huanxi; Zheng, Linli; Qin, Shuhang; Liu, Longshan; Yuan, Xiaopeng; Fu, Qian; Li, Jun; Deng, Ronghai; Deng, Suxiong; Yu, Fangchao; He, Xiaoshun; Wang, Changxi
2018-01-05
This study aimed to evaluate the predictive power of five available delayed graft function (DGF)-prediction models for kidney transplants in the Chinese population. Among the five models, the Irish 2010 model scored the best in performance for the Chinese population. Irish 2010 model had an area under the receiver operating characteristic (ROC) curve of 0.737. Hosmer-Lemeshow goodness-of-fit test showed that the Irish 2010 model had a strong correlation between the calculated DGF risk and the observed DGF incidence ( p = 0.887). When Irish 2010 model was used in the clinic, the optimal upper cut-off was set to 0.5 with the best positive likelihood ratio, while the lower cut-off was set to 0.1 with the best negative likelihood ratio. In the subgroup of donor aged ≤ 5, the observed DGF incidence was significantly higher than the calculated DGF risk by Irish 2010 model (27% vs. 9%). A total of 711 renal transplant cases using deceased donors from China Donation after Citizen's Death Program at our center between February 2007 and August 2016 were included in the analysis using the five predictive models (Irish 2010, Irish 2003, Chaphal 2014, Zaza 2015, Jeldres 2009). Irish 2010 model has the best predictive power for DGF risk in Chinese population among the five models. However, it may not be suitable for allograft recipients whose donor aged ≤ 5-year-old.
Variance Function Partially Linear Single-Index Models1.
Lian, Heng; Liang, Hua; Carroll, Raymond J
2015-01-01
We consider heteroscedastic regression models where the mean function is a partially linear single index model and the variance function depends upon a generalized partially linear single index model. We do not insist that the variance function depend only upon the mean function, as happens in the classical generalized partially linear single index model. We develop efficient and practical estimation methods for the variance function and for the mean function. Asymptotic theory for the parametric and nonparametric parts of the model is developed. Simulations illustrate the results. An empirical example involving ozone levels is used to further illustrate the results, and is shown to be a case where the variance function does not depend upon the mean function.
Directory of Open Access Journals (Sweden)
Tsair-Fwu Lee
Full Text Available Symptomatic radiation pneumonitis (SRP, which decreases quality of life (QoL, is the most common pulmonary complication in patients receiving breast irradiation. If it occurs, acute SRP usually develops 4-12 weeks after completion of radiotherapy and presents as a dry cough, dyspnea and low-grade fever. If the incidence of SRP is reduced, not only the QoL but also the compliance of breast cancer patients may be improved. Therefore, we investigated the incidence SRP in breast cancer patients after hybrid intensity modulated radiotherapy (IMRT to find the risk factors, which may have important effects on the risk of radiation-induced complications.In total, 93 patients with breast cancer were evaluated. The final endpoint for acute SRP was defined as those who had density changes together with symptoms, as measured using computed tomography. The risk factors for a multivariate normal tissue complication probability model of SRP were determined using the least absolute shrinkage and selection operator (LASSO technique.Five risk factors were selected using LASSO: the percentage of the ipsilateral lung volume that received more than 20-Gy (IV20, energy, age, body mass index (BMI and T stage. Positive associations were demonstrated among the incidence of SRP, IV20, and patient age. Energy, BMI and T stage showed a negative association with the incidence of SRP. Our analyses indicate that the risk of SPR following hybrid IMRT in elderly or low-BMI breast cancer patients is increased once the percentage of the ipsilateral lung volume receiving more than 20-Gy is controlled below a limitation.We suggest to define a dose-volume percentage constraint of IV20< 37% (or AIV20< 310cc for the irradiated ipsilateral lung in radiation therapy treatment planning to maintain the incidence of SPR below 20%, and pay attention to the sequelae especially in elderly or low-BMI breast cancer patients. (AIV20: the absolute ipsilateral lung volume that received more than
Data Acquisition for Quality Loss Function Modelling
DEFF Research Database (Denmark)
Pedersen, Søren Nygaard; Howard, Thomas J.
2016-01-01
Quality loss functions can be a valuable tool when assessing the impact of variation on product quality. Typically, the input for the quality loss function would be a measure of the varying product performance and the output would be a measure of quality. While the unit of the input is given by t...
Energy Technology Data Exchange (ETDEWEB)
Ramos, M [Chemical and Nuclear Engineering Department, Polytechnic University of Valencia, Camino de Vera s/n 46022 Valencia (Spain); Ferrer, S [Chemical and Nuclear Engineering Department, Polytechnic University of Valencia, Camino de Vera s/n 46022 Valencia (Spain); Villaescusa, J I [Radiation Protection Service, Hospital Universitario La Fe, Avda Campanar, 21 46009 Valencia (Spain); Verdu, G [Chemical and Nuclear Engineering Department, Polytechnic University of Valencia, Camino de Vera s/n 46022 Valencia (Spain); Salas, M D [Public Health General Direction, Conselleria de Sanitat de Valencia, C/Micer Masco, 31 46021 Valencia (Spain); Cuevas, M D [Assistential Service General Direction, Conselleria de Sanitat de Valencia, C/Micer Masco, 31 46021 Valencia (Spain)
2005-02-07
The authors report on a method to calculate radiological risks, applicable to breast screening programs and other controlled medical exposures to ionizing radiation. In particular, it has been applied to make a risk assessment in the Valencian Breast Cancer Early Detection Program (VBCEDP) in Spain. This method is based on a parametric approach, through Markov processes, of hazard functions for radio-induced breast cancer incidence and mortality, with mean glandular breast dose, attained age and age-at-exposure as covariates. Excess relative risk functions of breast cancer mortality have been obtained from two different case-control studies exposed to ionizing radiation, with different follow-up time: the Canadian Fluoroscopy Cohort Study (1950-1987) and the Life Span Study (1950-1985 and 1950-1990), whereas relative risk functions for incidence have been obtained from the Life Span Study (1958-1993), the Massachusetts tuberculosis cohorts (1926-1985 and 1970-1985), the New York post-partum mastitis patients (1930-1981) and the Swedish benign breast disease cohort (1958-1987). Relative risks from these cohorts have been transported to the target population undergoing screening in the Valencian Community, a region in Spain with about four and a half million inhabitants. The SCREENRISK software has been developed to estimate radiological detriments in breast screening. Some hypotheses corresponding to different screening conditions have been considered in order to estimate the total risk associated with a woman who takes part in all screening rounds. In the case of the VBCEDP, the total radio-induced risk probability for fatal breast cancer is in a range between [5 x 10{sup -6}, 6 x 10{sup -4}] versus the natural rate of dying from breast cancer in the Valencian Community which is 9.2 x 10{sup -3}. The results show that these indicators could be included in quality control tests and could be adequate for making comparisons between several screening programs.
International Nuclear Information System (INIS)
Ramos, M; Ferrer, S; Villaescusa, J I; Verdu, G; Salas, M D; Cuevas, M D
2005-01-01
The authors report on a method to calculate radiological risks, applicable to breast screening programs and other controlled medical exposures to ionizing radiation. In particular, it has been applied to make a risk assessment in the Valencian Breast Cancer Early Detection Program (VBCEDP) in Spain. This method is based on a parametric approach, through Markov processes, of hazard functions for radio-induced breast cancer incidence and mortality, with mean glandular breast dose, attained age and age-at-exposure as covariates. Excess relative risk functions of breast cancer mortality have been obtained from two different case-control studies exposed to ionizing radiation, with different follow-up time: the Canadian Fluoroscopy Cohort Study (1950-1987) and the Life Span Study (1950-1985 and 1950-1990), whereas relative risk functions for incidence have been obtained from the Life Span Study (1958-1993), the Massachusetts tuberculosis cohorts (1926-1985 and 1970-1985), the New York post-partum mastitis patients (1930-1981) and the Swedish benign breast disease cohort (1958-1987). Relative risks from these cohorts have been transported to the target population undergoing screening in the Valencian Community, a region in Spain with about four and a half million inhabitants. The SCREENRISK software has been developed to estimate radiological detriments in breast screening. Some hypotheses corresponding to different screening conditions have been considered in order to estimate the total risk associated with a woman who takes part in all screening rounds. In the case of the VBCEDP, the total radio-induced risk probability for fatal breast cancer is in a range between [5 x 10 -6 , 6 x 10 -4 ] versus the natural rate of dying from breast cancer in the Valencian Community which is 9.2 x 10 -3 . The results show that these indicators could be included in quality control tests and could be adequate for making comparisons between several screening programs
Modelling absorption in porous asphalt concrete for oblique incident sound waves
Bezemer-Krijnen, Marieke; Wijnant, Ysbrand H.; de Boer, Andries; Sas, P; Moens, D.; Denayer, H.
2014-01-01
A numerical model to predict the sound absorption of porous asphalt has been developed. The approach is a combination between a microstructural approach and a finite element approach. The model used to describe the viscothermal properties of the air inside the pores of the asphalt is the low reduced
Bezemer-Krijnen, Marieke; Wijnant, Ysbrand H.; de Boer, Andries; Glorieux, C.
2015-01-01
Sound absorption of porous asphalt pavements is an important property when reducing tyre-road noise. A hybrid model has been developed to predict the sound absorption of porous roads. This model is a combination of an analytical analysis of the sound eld and a numerical approach, including both the
Directory of Open Access Journals (Sweden)
Ljubenov Vladan L.
2014-01-01
Full Text Available In this paper we present the results of calculations and analyses of the integral particle reflection coefficient of photons for oblique photon incidence on planar targets, in the domain of initial photon energies from 100 keV to 300 keV. The results are based on the Monte Carlo simulations of the photon reflection from water, concrete, aluminum, iron, and copper materials, performed by the MCNP code. It has been observed that the integral particle reflection coefficient as a function of the ratio of total cross-section of photons and effective atomic number of target material shows universal behavior for all the analyzed shielding materials in the selected energy domain. Analytical formulas for different angles of photon incidence have been proposed, which describe the reflection of photons for all the materials and energies analyzed.
Hapugoda, J. C.; Sooriyarachchi, M. R.
2017-09-01
Survival time of patients with a disease and the incidence of that particular disease (count) is frequently observed in medical studies with the data of a clustered nature. In many cases, though, the survival times and the count can be correlated in a way that, diseases that occur rarely could have shorter survival times or vice versa. Due to this fact, joint modelling of these two variables will provide interesting and certainly improved results than modelling these separately. Authors have previously proposed a methodology using Generalized Linear Mixed Models (GLMM) by joining the Discrete Time Hazard model with the Poisson Regression model to jointly model survival and count model. As Aritificial Neural Network (ANN) has become a most powerful computational tool to model complex non-linear systems, it was proposed to develop a new joint model of survival and count of Dengue patients of Sri Lanka by using that approach. Thus, the objective of this study is to develop a model using ANN approach and compare the results with the previously developed GLMM model. As the response variables are continuous in nature, Generalized Regression Neural Network (GRNN) approach was adopted to model the data. To compare the model fit, measures such as root mean square error (RMSE), absolute mean error (AME) and correlation coefficient (R) were used. The measures indicate the GRNN model fits the data better than the GLMM model.
A DSM-based framework for integrated function modelling
DEFF Research Database (Denmark)
Eisenbart, Boris; Gericke, Kilian; Blessing, Lucienne T. M.
2017-01-01
an integrated function modelling framework, which specifically aims at relating between the different function modelling perspectives prominently addressed in different disciplines. It uses interlinked matrices based on the concept of DSM and MDM in order to facilitate cross-disciplinary modelling and analysis...
Bayesian Joint Modeling of Multiple Brain Functional Networks
Lukemire, Joshua; Kundu, Suprateek; Pagnoni, Giuseppe; Guo, Ying
2017-01-01
Brain function is organized in coordinated modes of spatio-temporal activity (functional networks) exhibiting an intrinsic baseline structure with variations under different experimental conditions. Existing approaches for uncovering such network structures typically do not explicitly model shared and differential patterns across networks, thus potentially reducing the detection power. We develop an integrative modeling approach for jointly modeling multiple brain networks across experimental...
Functional Curriculum Models for Secondary Students with Mild Mental Impairment
Bouck, Emily C.
2009-01-01
This paper analyzed 10 commercially available functional curriculum models designed for secondary students with mild-to-moderate mental impairment. The models were examined with respect to the inclusion of functional curriculum components, the domains and subdomains of adulthood, the materials identified by the model to be used to deliver the…
A Functional Test Platform for the Community Land Model
Energy Technology Data Exchange (ETDEWEB)
Xu, Yang [ORNL; Thornton, Peter E [ORNL; King, Anthony Wayne [ORNL; Steed, Chad A [ORNL; Gu, Lianhong [ORNL; Schuchart, Joseph [ORNL
2014-01-01
A functional test platform is presented to create direct linkages between site measurements and the process-based ecosystem model within the Community Earth System Models (CESM). The platform consists of three major parts: 1) interactive user interfaces, 2) functional test model and 3) observational datasets. It provides much needed integration interfaces for both field experimentalists and ecosystem modelers to improve the model s representation of ecosystem processes within the CESM framework without large software overhead.
Numerical Models for Obliquely Incident Waves in Surf and Swash Zones
National Research Council Canada - National Science Library
Karjadi, Entin
1997-01-01
Time-dependent numerical models are developed to predict the temporal and cross-shore variations of the free surface elevation and the cross-shore and alongshore fluid velocities in the swash and surf...
Cyber Incidents Involving Control Systems
Energy Technology Data Exchange (ETDEWEB)
Robert J. Turk
2005-10-01
The Analysis Function of the US-CERT Control Systems Security Center (CSSC) at the Idaho National Laboratory (INL) has prepared this report to document cyber security incidents for use by the CSSC. The description and analysis of incidents reported herein support three CSSC tasks: establishing a business case; increasing security awareness and private and corporate participation related to enhanced cyber security of control systems; and providing informational material to support model development and prioritize activities for CSSC. The stated mission of CSSC is to reduce vulnerability of critical infrastructure to cyber attack on control systems. As stated in the Incident Management Tool Requirements (August 2005) ''Vulnerability reduction is promoted by risk analysis that tracks actual risk, emphasizes high risk, determines risk reduction as a function of countermeasures, tracks increase of risk due to external influence, and measures success of the vulnerability reduction program''. Process control and Supervisory Control and Data Acquisition (SCADA) systems, with their reliance on proprietary networks and hardware, have long been considered immune to the network attacks that have wreaked so much havoc on corporate information systems. New research indicates this confidence is misplaced--the move to open standards such as Ethernet, Transmission Control Protocol/Internet Protocol, and Web technologies is allowing hackers to take advantage of the control industry's unawareness. Much of the available information about cyber incidents represents a characterization as opposed to an analysis of events. The lack of good analyses reflects an overall weakness in reporting requirements as well as the fact that to date there have been very few serious cyber attacks on control systems. Most companies prefer not to share cyber attack incident data because of potential financial repercussions. Uniform reporting requirements will do much to make this
Modeling interface roughness scattering in a layered seabed for normal-incident chirp sonar signals.
Tang, Dajun; Hefner, Brian T
2012-04-01
Downward looking sonar, such as the chirp sonar, is widely used as a sediment survey tool in shallow water environments. Inversion of geo-acoustic parameters from such sonar data precedes the availability of forward models. An exact numerical model is developed to initiate the simulation of the acoustic field produced by such a sonar in the presence of multiple rough interfaces. The sediment layers are assumed to be fluid layers with non-intercepting rough interfaces.
Awad, E M
1999-01-01
In this work, we have studied the effect of the radiation damage caused by the incident particles on the activation energy of etching for CR-39 samples. The damage produced by the incident particle is expressed in terms of the linear energy transfer (LET). CR-39 samples from American Acrylic were irradiated to three different LET particles. These are N (LET sub 2 sub 0 sub 0 = 20 KeV/mu m) as a light particle, Fe (LET sub 2 sub 0 sub 0 = 110 KeV/mu m) as a medium particle and fission fragments (ff) from a sup 2 sup 5 sup 2 Cf source as heavy particles. In general the bulk etch rate was calculated using the weight difference method and the track etch rate was determined using the track geometry at various temperatures (50-90 deg. C) and concentrations (4-9 N) of the NaOH etchant. The average activation energy E sub b related to the bulk etch rate v sub b was calculated from 1n v sub b vs. 1/T. The average activation energy E sub t related to the track etch rate v sub t was estimated from 1n v sub t vs. 1/T. It...
Exact 2-point function in Hermitian matrix model
International Nuclear Information System (INIS)
Morozov, A.; Shakirov, Sh.
2009-01-01
J. Harer and D. Zagier have found a strikingly simple generating function [1,2] for exact (all-genera) 1-point correlators in the Gaussian Hermitian matrix model. In this paper we generalize their result to 2-point correlators, using Toda integrability of the model. Remarkably, this exact 2-point correlation function turns out to be an elementary function - arctangent. Relation to the standard 2-point resolvents is pointed out. Some attempts of generalization to 3-point and higher functions are described.
On Support Functions for the Development of MFM Models
DEFF Research Database (Denmark)
Heussen, Kai; Lind, Morten
2012-01-01
A modeling environment and methodology are necessary to ensure quality and reusability of models in any domain. For MFM in particular, as a tool for modeling complex systems, awareness has been increasing for this need. Introducing the context of modeling support functions, this paper provides...... a review of MFM applications, and contextualizes the model development with respect to process design and operation knowledge. Developing a perspective for an environment for MFM-oriented model- and application-development a tool-chain is outlined and relevant software functions are discussed....... With a perspective on MFM-modeling for existing processes and automation design, modeling stages and corresponding formal model properties are identified. Finally, practically feasible support functions and model-checks to support the model-development are suggested....
Drongelen AW van; Roszek B; Hilbers-Modderman ESM; Kallewaard M; Wassenaar C; LGM
2002-01-01
This RIVM study was performed to gain insight into wheelchair-related incidents with powered and manual wheelchairs reported to the USA FDA, the British MDA and the Dutch Center for Quality and Usability Research of Technical Aids (KBOH). The data in the databases do not indicate that incidents with
Pei, Zhiyong; Liu, Jielin; Liu, Manjiao; Zhou, Wenchao; Yan, Pengcheng; Wen, Shaojun; Chen, Yubao
2018-03-01
Essential hypertension (EH) has become a major chronic disease around the world. To build a risk-predicting model for EH can help to interpose people's lifestyle and dietary habit to decrease the risk of getting EH. In this study, we constructed a EH risk-predicting model considering both environmental and genetic factors with support vector machine (SVM). The data were collected through Epidemiological investigation questionnaire from Beijing Chinese Han population. After data cleaning, we finally selected 9 environmental factors and 12 genetic factors to construct the predicting model based on 1200 samples, including 559 essential hypertension patients and 641 controls. Using radial basis kernel function, predictive accuracy via SVM with function with only environmental factor and only genetic factor were 72.8 and 54.4%, respectively; after considering both environmental and genetic factor the accuracy improved to 76.3%. Using the model via SVM with Laplacian function, the accuracy with only environmental factor and only genetic factor were 76.9 and 57.7%, respectively; after combining environmental and genetic factor, the accuracy improved to 80.1%. The predictive accuracy of SVM model constructed based on Laplacian function was higher than radial basis kernel function, as well as sensitivity and specificity, which were 63.3 and 86.7%, respectively. In conclusion, the model based on SVM with Laplacian kernel function had better performance in predicting risk of hypertension. And SVM model considering both environmental and genetic factors had better performance than the model with environmental or genetic factors only.
Martin, Roland; Komatitsch, Dimitri; Bruthiaux, Emilien; Gedney, Stephen D.
2010-05-01
We present and discuss here two different unsplit formulations of the frequency shift PML based on convolution or non convolution integrations of auxiliary memory variables. Indeed, the Perfectly Matched Layer absorbing boundary condition has proven to be very efficient from a numerical point of view for the elastic wave equation to absorb both body waves with non-grazing incidence and surface waves. However, at grazing incidence the classical discrete Perfectly Matched Layer method suffers from large spurious reflections that make it less efficient for instance in the case of very thin mesh slices, in the case of sources located very close to the edge of the mesh, and/or in the case of receivers located at very large offset. In [1] we improve the Perfectly Matched Layer at grazing incidence for the seismic wave equation based on an unsplit convolution technique. This improved PML has a cost that is similar in terms of memory storage to that of the classical PML. We illustrate the efficiency of this improved Convolutional Perfectly Matched Layer based on numerical benchmarks using a staggered finite-difference method on a very thin mesh slice for an isotropic material and show that results are significantly improved compared with the classical Perfectly Matched Layer technique. We also show that, as the classical model, the technique is intrinsically unstable in the case of some anisotropic materials. In this case, retaining an idea of [2], this has been stabilized by adding correction terms adequately along any coordinate axis [3]. More specifically this has been applied to the spectral-element method based on a hybrid first/second order time integration scheme in which the Newmark time marching scheme allows us to match perfectly at the base of the absorbing layer a velocity-stress formulation in the PML and a second order displacement formulation in the inner computational domain.Our CPML unsplit formulation has the advantage to reduce the memory storage of CPML
Novel, high incidence exercise-induced muscle bleeding model in hemophilia B mice
DEFF Research Database (Denmark)
Tranholm, M.; Kristensen, Annemarie Thuri; Broberg, M. L.
2015-01-01
INTRODUCTION: Muscle hematomas are the second most common complication of hemophilia and insufficient treatment may result in serious and even life-threatening complications. Hemophilic dogs and rats do experience spontaneous muscle bleeding, but currently, no experimental animal model is available...... specifically investigating spontaneous muscle bleeds in a hemophilic setting. AIM: The objective of this study was to develop a model of spontaneous muscle bleeds in hemophilia B mice. We hypothesized that treadmill exercise would induce muscle bleeds in hemophilia B mice but not in normal non-hemophilic mice...... and that treatment with recombinant factor IX (rFIX) before treadmill exercise could prevent the occurrence of pathology. METHODS: A total of 203 mice (123 F9-KO and 80 C57BL/6NTac) were included in three separate studies: (i) the model implementation study investigating the bleeding pattern in hemophilia B mice...
Validation of aerodynamic parameters at high angles of attack for RAE high incidence research models
Ross, A. Jean; Edwards, Geraldine F.; Klein, Vladislav; Batterson, James G.
1987-01-01
Two series of free-flight tests have been conducted for combat aircraft configuration research models in order to investigate flight behavior near departure conditions as well as to obtain response data from which aerodynamic characteristics can be derived. The structure of the mathematical model and values for the mathematical derivatives have been obtained through an analysis of the first series, using stepwise regression. The results thus obtained are the bases of the design of active control laws. Flight test results for a novel configuration are compared with predicted responses.
Modelling Strategies for Functional Magnetic Resonance Imaging
DEFF Research Database (Denmark)
Madsen, Kristoffer Hougaard
2009-01-01
and generalisations to higher order arrays are considered. Additionally, an application of the natural conjugate prior for supervised learning in the general linear model to efficiently incorporate prior information for supervised analysis is presented. Further extensions include methods to model nuisance effects...... in fMIR data thereby suppressing noise for both supervised and unsupervised analysis techniques....
Albert, Paul S
2018-02-21
Prediction of preterm birth as well as characterizing the etiological factors affecting both the recurrence and incidence of preterm birth (defined as gestational age at birth ≤ 37 wk) are important problems in obstetrics. The National Institute of Child Health and Human Development (NICHD) consecutive pregnancy study recently examined this question by collecting data on a cohort of women with at least 2 pregnancies over a fixed time interval. Unfortunately, measurement error due to the dating of conception may induce sizable error in computing gestational age at birth. This article proposes a flexible approach that accounts for measurement error in gestational age when making inference. The proposed approach is a hidden Markov model that accounts for measurement error in gestational age by exploiting the relationship between gestational age at birth and birth weight. We initially model the measurement error as being normally distributed, followed by a mixture of normals that has been proposed on the basis of biological considerations. We examine the asymptotic bias of the proposed approach when measurement error is ignored and also compare the efficiency of this approach to a simpler hidden Markov model formulation where only gestational age and not birth weight is incorporated. The proposed model is compared with alternative models for estimating important covariate effects on the risk of subsequent preterm birth using a unique set of data from the NICHD consecutive pregnancy study. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.
International Nuclear Information System (INIS)
Tinger, Alfred; Wasserman, Todd H.; Klein, Eric E.; Miller, Elizabeth A.; Roberts, Tracy; Piephoff, James V.; Kucik, Nancy A.
1997-01-01
Purpose: There is an increased incidence of breast cancer following mantle field radiation therapy for Hodgkin's disease (HD). We reviewed the experience at the Mallinckrodt Institute of Radiology (MIR) for radiation factors related to the development of breast cancer after mantle field radiation therapy for HD. Methods: The radiation therapy records of 152 women treated with mantle field irradiation for HD at MIR between 1966-1985 were reviewed for the development of breast cancer and treatment-related factors. All patients had a minimum of 5 years of follow-up. The treatment era (1966-1974 vs. 1975-1985), stage of HD, mediastinal dose, axillary dose, maximum dose from the anterior field (anterior d max dose), the anterior-posterior:posterior-anterior (AP:PA) ratio, age at the time of treatment, length of follow-up, and history of splenectomy were analyzed as possible contributing factors for the development of breast cancer. The observed number of breast cancers was compared to the expected number based on age-adjusted incidences from the Connecticut Tumor Registry. Results: Ten breast cancers occurred in the population. Eight involved an upper outer quadrant. In a multivariate analysis, the development of breast cancer was significantly associated with axillary dose. Patients in the early treatment era were at an increased risk for the development of breast cancer due to high anterior d max and breast doses from weighting the fields anteriorly on a low energy linear accelerator. The use of current radiation therapy techniques was not related to an increased risk of breast cancer with a median follow-up of 13 years. Conclusions: A high dose to the axilla and the anterior d max point is significantly associated with the development of breast cancer after mantle field irradiation for HD. Efforts to protect the breast from high doses will likely lessen the increased risk of breast cancer in women treated with radiation therapy for HD
Fortrie, Gijs; Manintveld, Olivier C; Caliskan, Kadir; Bekkers, Jos A; Betjes, Michiel G H
2016-08-01
Although chronic deterioration in renal function is frequently seen after cardiac transplantation, which is partly explained by the use of calcineurin inhibitors, data on the consequences of acute kidney injury (AKI) after cardiac transplantation are scarce. In the current study, the incidence of AKI and its impact on mortality and renal function was evaluated. Five hundred thirty-one cardiac transplant recipients (age ≥18 years) were evaluated for the postoperative incidence of AKI defined by the Kidney Disease Improving Global Outcome criteria. Secondary outcomes were renal function and mortality during the first postoperative year. Overall, 405 (76%) recipients met the AKI criteria of which 211 (40%) had AKI stage I, 119 (22%) stage II, 75 (14%) stage III, and 25 patients (5%) required renal replacement therapy (RRT). One-year mortality rates in patients without AKI, stages I, II, and III were 4.8%, 7.6%, 11.8%, and 14.7%, respectively (log-rank test for trend, P = 0.008). In patients that required RRT 1-year mortality was 28.2% (log-rank test P = 0.001). In multivariable analysis only AKI requiring RRT was an independent predictor of 1-year mortality (hazard ratio, 2.75; P = 0.03). Improvement in renal function, compared with baseline values, occurred in 27% of recipients 1 month after transplantation. This was less likely to occur after previous AKI (P ≤ 0.04). The AKI stages I to III were independently proportionally associated with a worse renal function 1 year after transplantation (P ≤ 0.01). Acute kidney injury is highly frequent after cardiac transplantation, and the stage of AKI is associated with increased mortality and impaired renal function in the first postoperative year.
Preciado, J; Pérez, C; Calzada, M; Preciado, P
2005-05-01
The aim of this study was calculate the prevalence and incidence of voice disorders among teaching staff of La Rioja, Spain. We carried out a transversal study of voice disorders in teaching staff of La Rioja (a random sample of 931 of 3113 teachers) and a longitudinal study (we collect the new cases during the 3 years which lasts the study). 527 teachers of random sample took part of study: 332 female (63%) and 195 male (37%). All of teachers fill in a standard questionnaire, ENT and function vocal examination, videolaryngostroboscopy and acoustic analysis with MDVP. The prevalence of voice disorders among La Rioja Teachers was 57%: 20.3% for organic lesions [nodular lesions (14%), polyps (2%), submucous suffusions (1.4%), edema Reinke (1.2%) Sulcus (0.4%), scalp (0.6%), leucoplasia (0.2%) vocal cord paralysis (0.2%)] 8.1% for chronic laryngitis [not specific (2.8%), smoke (3.9%) gastroe-sofageal reflux (2.5%)] and 29% for functional lesions [hyperfunctional dysphonia (7.5%) hypofunctional dysphonia (0.4%) vocal overefforts (18%) hyperplasia false cords (2.8)]. The incidence rate was 4 new cases each 1000 teachers and year. Organic lesions were more prevalent in women (25.4%) than in men (9.5%), but functional lesions and chronic laryngitis were more prevalent in men (36.5% and 13.2%) than in women (24% and 5%).
Gu, Liubao; Huang, Liji; Wu, Haidi; Lou, Qinglin; Bian, Rongwen
2017-05-01
Serum uric acid has shown to be a predictor of renal disease progression in most but not all studies. This study aims to test whether renal function-normalized serum uric acid is superior to serum uric acid as the predictor of incident chronic kidney disease in type 2 diabetes mellitus patients. In this study, 1339 type 2 diabetes mellitus patients with estimated glomerular filtration rate ⩾60 mL/min/1.73 m 2 and normouricemia were included. Renal function-normalized serum uric acid was calculated using serum uric acid/creatinine. Cox regression analysis was used to estimate the association between serum uric acid, renal function-normalized serum uric acid and incident chronic kidney disease. In total, 74 (5.53%) patients developed to chronic kidney disease 3 or greater during a median follow-up of 4 years, with older ages, longer diabetes duration and lower estimated glomerular filtration rate at baseline. The decline rate of estimated glomerular filtration rate was positively correlated with serum uric acid/creatinine ( r = 0.219, p type 2 diabetes mellitus patients.
Functional modeling of neural-glial interaction
DEFF Research Database (Denmark)
Postnov, D.E.; Ryazanova, L.S.; Sosnovtseva, Olga
2007-01-01
We propose a generalized mathematical model for a small neural-glial ensemble. The model incorporates subunits of the tripartite synapse that includes a presynaptic neuron, the synaptic terminal itself, a postsynaptic neuron, and a glial cell. The glial cell is assumed to be activated via two...... different pathways: (i) the fast increase of intercellular [K+] produced by the spiking activity of the postsynaptic neuron, and (ii) the slow production of a mediator triggered by the synaptic activity. Our model predicts the long-term potentiation of the postsynaptic neuron as well as various [Ca2...
Connecting to Get Things Done: A Conceptual Model of the Process Used to Respond to Bias Incidents
LePeau, Lucy A.; Morgan, Demetri L.; Zimmerman, Hilary B.; Snipes, Jeremy T.; Marcotte, Beth A.
2016-01-01
In this study, we interviewed victims of bias incidents and members of a bias response team to investigate the process the team used to respond to incidents. Incidents included acts of sexism, homophobia, and racism on a large, predominantly White research university in the Midwest. Data were analyzed using a 4-stage coding process. The emergent…
Mechanical modeling of skeletal muscle functioning
van der Linden, B.J.J.J.
1998-01-01
For movement of body or body segments is combined effort needed of the central nervous system and the muscular-skeletal system. This thesis deals with the mechanical functioning of skeletal muscle. That muscles come in a large variety of geometries, suggest the existence of a relation between muscle
Density functional theory and multiscale materials modeling
Indian Academy of Sciences (India)
In the macroscopic length scale, however, matter is usually treated as a continuous medium and a description using local mass density, energy density and other related density functions has been found to be quite appropriate. A unique single unified theoretical framework that emerges through the density concept at these ...
The Use of Function/Means Trees for Modelling Technical, Semantic and Business Functions
DEFF Research Database (Denmark)
Robotham, Antony John
2000-01-01
This paper considers the feasibility of using the function/means tree to create a single tree for a complete motor vehicle. It is argued that function/means trees can be used for modelling technical and semantic functions, but it is an inappropriate method for business functions when one tree...... of the vehicle is required. Life cycle modelling provides an effective means for determining all the required purpose functions and is considered a more effective method than the function/means tree for this task when the structure and mode of operation of the vehicle is well defined and understood....
Dynamics of synthetic drugs transmission model with psychological addicts and general incidence rate
Ma, Mingju; Liu, Sanyang; Xiang, Hong; Li, Jun
2018-02-01
Synthetic drugs are replacing traditional ones and becoming the main popular ones gradually, which have given rise to serious social issues in recent years. In this paper, a synthetic drugs transmission model with psychological addicts and general contact rate is proposed. The local and global stabilities are decided by the basic reproduction number R0. By analyzing the sensitivity of parameters, we obtain that controlling psychological addiction is better than drugs treatment. These results are verified by numerical simulations.
The characteristic function of rough Heston models
Euch, Omar El; Rosenbaum, Mathieu
2016-01-01
It has been recently shown that rough volatility models, where the volatility is driven by a fractional Brownian motion with small Hurst parameter, provide very relevant dynamics in order to reproduce the behavior of both historical and implied volatilities. However, due to the non-Markovian nature of the fractional Brownian motion, they raise new issues when it comes to derivatives pricing. Using an original link between nearly unstable Hawkes processes and fractional volatility models, we c...
Ren, Zijian; Ma, Chunyong; Chen, Lu; Chen, Ge
2016-05-01
A high-efficiency anisotropic model for bidirectional reflectance distribution function (BRDF) of seawater covered by oil slicks (SWCOS) was proposed. This model was set by combining a BRDF model for anisotropic rough sea surface whose slopes follow Gaussian distribution and the two-beam inference theory of a thin film. We have simulated the BRDFs of oil slicks by using the above model and the measured complex refractive index data of Romashkino crude oil. In addition, the relationships between the BRDF of oil slicks and the wind speed of sea surface, thickness of oil slick, complex refractive index of crude oil and the incident zenith angle were analyzed. Also, the differences between optical characteristics of clean water and of polluted water were discussed in the context of the optical contrast of SWCOS. With high simulation speed and reliable simulation precision, this model provides a theoretical basis for rapid detection of oil spill.
DEFF Research Database (Denmark)
Kehres, Jan; Pedersen, Thomas; Masini, Federico
2016-01-01
-incidence small-angle X-ray scattering (GISAXS) in transmission through 10 µm-thick entrance and exit windows by using micro-focused beams. An additional thinning of the Pyrex glass reactor lid allows simultaneous acquisition of the grazing-incidence wide-angle X-ray scattering (GIWAXS). In situ experiments......The design, fabrication and performance of a novel and highly sensitive micro-reactor device for performing in situ grazing-incidence X-ray scattering experiments of model catalyst systems is presented. The design of the reaction chamber, etched in silicon on insulator (SIO), permits grazing...
Genetic Prediction Models and Heritability Estimates for Functional ...
African Journals Online (AJOL)
This paper discusses these methodologies and their advantages and disadvantages. Heritability estimates obtained from these models are also reviewed. Linear methodologies can model binary and actual longevity, while RR and TM methodologies model binary survival. PH procedures model the hazard function of a cow ...
Directory of Open Access Journals (Sweden)
Esther D. Kim
2017-11-01
Discussion: Higher AIx and cPP, which are indicative of abnormal wave reflections in distal vessels, are associated with, and might contribute to, declining cognitive function in patients starting hemodialysis.
Energy Technology Data Exchange (ETDEWEB)
Donovan, E. M.; James, H.; Bonora, M.; Yarnold, J. R.; Evans, P. M. [Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton SM2 5PT (United Kingdom); Physics Department, Ipswich Hospital NHS Foundation Trust, Ipswich IP4 5PD (United Kingdom); Department of Academic Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton SM2 5PT, United Kingdom and School of Radiotherapy, University of Milan, Milan 20122 (Italy); Department of Academic Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton SM2 5PT (United Kingdom); Centre for Vision Speech and Signal Processing, University of Surrey, Guildford GU2 7XH (United Kingdom)
2012-10-15
Purpose: To compare organ specific cancer incidence risks for standard and complex external beam radiotherapy (including cone beam CT verification) following breast conservation surgery for early breast cancer.Method: Doses from breast radiotherapy and kilovoltage cone beam CT (CBCT) exposures were obtained from thermoluminescent dosimeter measurements in an anthropomorphic phantom in which the positions of radiosensitive organs were delineated. Five treatment deliveries were investigated: (i) conventional tangential field whole breast radiotherapy (WBRT), (ii) noncoplanar conformal delivery applicable to accelerated partial beast irradiation (APBI), (iii) two-volume simultaneous integrated boost (SIB) treatment, (iv) forward planned three-volume SIB, and (v) inverse-planned three volume SIB. Conformal and intensity modulated radiotherapy methods were used to plan the complex treatments. Techniques spanned the range from simple methods appropriate for patient cohorts with a low cancer recurrence risk to complex plans relevant to cohorts with high recurrence risk. Delineated organs at risk included brain, salivary glands, thyroid, contralateral breast, left and right lung, esophagus, stomach, liver, colon, and bladder. Biological Effects of Ionizing Radiation (BEIR) VII cancer incidence models were applied to the measured mean organ doses to determine lifetime attributable risk (LAR) for ages at exposure from 35 to 80 yr according to radiotherapy techniques, and included dose from the CBCT imaging. Results: All LAR decreased with age at exposure and were lowest for brain, thyroid, liver, and bladder (<0.1%). There was little dependence of LAR on radiotherapy technique for these organs and for colon and stomach. LAR values for the lungs for the three SIB techniques were two to three times those from WBRT and APBI. Uncertainties in the LAR models outweigh any differences in lung LAR between the SIB methods. Constraints in the planning of the SIB methods ensured that
A Functional Model of the Aesthetic Response
Directory of Open Access Journals (Sweden)
Daniel Conrad
2010-01-01
Full Text Available In a process of somatic evolution, the brain semi-randomly generates initially-unstable neural circuits that are selectively stabilized if they succeed in making sense out of raw sensory input. The human aesthetic response serves the function of stabilizing the circuits that successfully mediate perception and interpretation, making those faculties more agile, conferring selective advantage. It is triggered by structures in art and nature that provoke the making of sense. Art is deliberate human action aimed at triggering the aesthetic response in others; thus, if successful, it serves the same function of making perception and interpretation more agile. These few principles initiate a cascade of emergent phenomena which account for many observed qualities of aesthetics, including universality and idiosyncrasy of taste, the relevance of artists’ intentions, the virtues of openness and resonance, the dysfunction of formulaic art, and the fact that methods of art correspond to modes of perceptual transformation.
Density functional theory and multiscale materials modeling*
Indian Academy of Sciences (India)
Unknown
Here the hardness kernel (Berkowitz et al 1985;. Ghosh 1990), ηµν(r, r′), represents the energy functional derivative . )( )( ],[. ),(. 2......... ′. =′ r r rr ν. µ β α. µν δρ δρ ρρ δ η. F. (27). We now specialize to the case of a set of atoms (say, M in number) located at the fixed positions {Ri} corre- sponding to a ...
A risk prediction model of the incidence of occupational low back pain among mining workers
Directory of Open Access Journals (Sweden)
Fikry Effendi
2011-08-01
Full Text Available Background: Low Back Pain (LBP is the most frequently reported musculoskeletal disorder in workers. This study was aimed to develop risk prediction model of low back pain that can be used to prevent the recurring low back pain attack.Methods: The study was case-control design based on the industrial community by using ergonomical approach. Total samples were 91 workers for cases and 91 workers for controls. Workers suffering for low back pain in the last 6 months served as cases, and those from the same age group and receiving the same amount of exposure without any symptoms of low back pain served as controls. Risk factors include socio-demographic factors, socio-ocupational factors, physical working environmental factors, non-physical environmental factors, and biomechanics factors. Receiver Operating Characreistics (ROC was used to describe relationship between true positive value (in vertical axis and false positive value (in horizontal axis in order to discover a risk predictive value of LBP.Results: The determinant risk factors for low back pain (LBP were bending work postures, waist rotation movement, manual lifting, unnatural work postures, those who had worked for more than 18 years, and irregular sport activities. By using ROC with 91.20% senstivity and 87.90% spesifi city, the calculated prediction value was 0.35. This is the cut-off point to discriminate workers with and without LBP. The risk predictors value of work-induced LBP calculated by linear equation of logistic regression varied between 0-11.25.Conclusion: The prediction model of work-induced LBP can be used for early detection of LBP to reduce the risk and prevent the recurrence of LBP. (Med J Indones. 2011; 20:212-6Keywords: Ergonomy, low back pain, prediction model, work-induced LBP
Updating a B. anthracis Risk Model with Field Data from a Bioterrorism Incident.
Hong, Tao; Gurian, Patrick L
2015-06-02
In this study, a Bayesian framework was applied to update a model of pathogen fate and transport in the indoor environment. Distributions for model parameters (e.g., release quantity of B. anthracis spores, risk of illness, spore setting velocity, resuspension rate, sample recovery efficiency, etc.) were updated by comparing model predictions with measurements of B. anthracis spores made after one of the 2001 anthrax letter attacks. The updating process, which was implemented by using Markov chain Monte Carlo (MCMC) methods, significantly reduced the uncertainties of inputs with uniformed prior estimates: total quantity of spores released, the amount of spores exiting the room, and risk to occupants. In contrast, uncertainties were not greatly reduced for inputs for which informed prior data were available: deposition rates, resuspension rates, and sample recovery efficiencies. This suggests that prior estimates of these quantities that were obtained from a review of the technical literature are consistent with the observed behavior of spores in an actual attack. Posterior estimates of mortality risk for people in the room, when the spores were released, are on the order of 0.01 to 0.1, which supports the decision to administer prophylactic antibiotics. Multivariate sensitivity analyses were conducted to assess how effective different measurements were at reducing uncertainty in the estimated risk for the prior scenario. This analysis revealed that if the size distribution of the released particulates is known, then environmental sampling can be limited to accurately characterizing floor concentrations; otherwise, samples from multiple locations, as well as particulate and building air circulation parameters, need to be measured.
Multiple time scales in modeling the incidence of infections acquired in intensive care units
Directory of Open Access Journals (Sweden)
Martin Wolkewitz
2016-09-01
Full Text Available Abstract Background When patients are admitted to an intensive care unit (ICU their risk of getting an infection will be highly depend on the length of stay at-risk in the ICU. In addition, risk of infection is likely to vary over calendar time as a result of fluctuations in the prevalence of the pathogen on the ward. Hence risk of infection is expected to depend on two time scales (time in ICU and calendar time as well as competing events (discharge or death and their spatial location. The purpose of this paper is to develop and apply appropriate statistical models for the risk of ICU-acquired infection accounting for multiple time scales, competing risks and the spatial clustering of the data. Methods A multi-center data base from a Spanish surveillance network was used to study the occurrence of an infection due to Methicillin-resistant Staphylococcus aureus (MRSA. The analysis included 84,843 patient admissions between January 2006 and December 2011 from 81 ICUs. Stratified Cox models were used to study multiple time scales while accounting for spatial clustering of the data (patients within ICUs and for death or discharge as competing events for MRSA infection. Results Both time scales, time in ICU and calendar time, are highly associated with the MRSA hazard rate and cumulative risk. When using only one basic time scale, the interpretation and magnitude of several patient-individual risk factors differed. Risk factors concerning the severity of illness were more pronounced when using only calendar time. These differences disappeared when using both time scales simultaneously. Conclusions The time-dependent dynamics of infections is complex and should be studied with models allowing for multiple time scales. For patient individual risk-factors we recommend stratified Cox regression models for competing events with ICU time as the basic time scale and calendar time as a covariate. The inclusion of calendar time and stratification by ICU
Yu, Wenya; Lv, Yipeng; Hu, Chaoqun; Liu, Xu; Chen, Haiping; Xue, Chen; Zhang, Lulu
2018-01-01
Emergency medical system for mass casualty incidents (EMS-MCIs) is a global issue. However, China lacks such studies extremely, which cannot meet the requirement of rapid decision-support system. This study aims to realize modeling EMS-MCIs in Shanghai, to improve mass casualty incident (MCI) rescue efficiency in China, and to provide a possible method of making rapid rescue decisions during MCIs. This study established a system dynamics (SD) model of EMS-MCIs using the Vensim DSS program. Intervention scenarios were designed as adjusting scales of MCIs, allocation of ambulances, allocation of emergency medical staff, and efficiency of organization and command. Mortality increased with the increasing scale of MCIs, medical rescue capability of hospitals was relatively good, but the efficiency of organization and command was poor, and the prehospital time was too long. Mortality declined significantly when increasing ambulances and improving the efficiency of organization and command; triage and on-site first-aid time were shortened if increasing the availability of emergency medical staff. The effect was the most evident when 2,000 people were involved in MCIs; however, the influence was very small under the scale of 5,000 people. The keys to decrease the mortality of MCIs were shortening the prehospital time and improving the efficiency of organization and command. For small-scale MCIs, improving the utilization rate of health resources was important in decreasing the mortality. For large-scale MCIs, increasing the number of ambulances and emergency medical professionals was the core to decrease prehospital time and mortality. For super-large-scale MCIs, increasing health resources was the premise.
Resnick, Barbara; Gruber-Baldini, Ann L; Hicks, Gregory; Ostir, Glen; Klinedinst, N Jennifer; Orwig, Denise; Magaziner, Jay
2016-07-01
Measurement of physical function post hip fracture has been conceptualized using multiple different measures. This study tested a comprehensive measurement model of physical function. This was a descriptive secondary data analysis including 168 men and 171 women post hip fracture. Using structural equation modeling, a measurement model of physical function which included grip strength, activities of daily living, instrumental activities of daily living, and performance was tested for fit at 2 and 12 months post hip fracture, and among male and female participants. Validity of the measurement model of physical function was evaluated based on how well the model explained physical activity, exercise, and social activities post hip fracture. The measurement model of physical function fit the data. The amount of variance the model or individual factors of the model explained varied depending on the activity. Decisions about the ideal way in which to measure physical function should be based on outcomes considered and participants. The measurement model of physical function is a reliable and valid method to comprehensively measure physical function across the hip fracture recovery trajectory. © 2015 Association of Rehabilitation Nurses.
Carter, Daniel J; Glaziou, Philippe; Lönnroth, Knut; Siroka, Andrew; Floyd, Katherine; Weil, Diana; Raviglione, Mario; Houben, Rein M G J; Boccia, Delia
2018-05-01
The End TB Strategy and the Sustainable Development Goals (SDGs) are intimately linked by their common targets and approaches. SDG 1 aims to end extreme poverty and expand social protection coverage by 2030. Achievement of SDG 1 is likely to affect the tuberculosis epidemic through a range of pathways. We estimate the reduction in global tuberculosis incidence that could be obtained by reaching SDG 1. We developed a conceptual framework linking key indicators of SDG 1 progress to tuberculosis incidence via well described risk factor pathways and populated it with data from the SDG data repository and the WHO tuberculosis database for 192 countries. Correlations and mediation analyses informed the strength of the association between the SDG 1 subtargets and tuberculosis incidence, resulting in a simplified framework for modelling. The simplified framework linked key indicators for SDG 1 directly to tuberculosis incidence. We applied an exponential decay model based on linear associations between SDG 1 indicators and tuberculosis incidence to estimate tuberculosis incidence in 2035. Ending extreme poverty resulted in a reduction in global incidence of tuberculosis of 33·4% (95% credible interval 15·5-44·5) by 2035 and expanding social protection coverage resulted in a reduction in incidence of 76·1% (45·2-89·9) by 2035; both pathways together resulted in a reduction in incidence of 84·3% (54·7-94·9). Full achievement of SDG 1 could have a substantial effect on the global burden of tuberculosis. Cross-sectoral approaches that promote poverty reduction and social protection expansion will be crucial complements to health interventions, accelerating progress towards the End TB targets. World Health Organization. Copyright © 2018 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.
Directory of Open Access Journals (Sweden)
Daniel J Carter, MSc
2018-05-01
Full Text Available Summary: Background: The End TB Strategy and the Sustainable Development Goals (SDGs are intimately linked by their common targets and approaches. SDG 1 aims to end extreme poverty and expand social protection coverage by 2030. Achievement of SDG 1 is likely to affect the tuberculosis epidemic through a range of pathways. We estimate the reduction in global tuberculosis incidence that could be obtained by reaching SDG 1. Methods: We developed a conceptual framework linking key indicators of SDG 1 progress to tuberculosis incidence via well described risk factor pathways and populated it with data from the SDG data repository and the WHO tuberculosis database for 192 countries. Correlations and mediation analyses informed the strength of the association between the SDG 1 subtargets and tuberculosis incidence, resulting in a simplified framework for modelling. The simplified framework linked key indicators for SDG 1 directly to tuberculosis incidence. We applied an exponential decay model based on linear associations between SDG 1 indicators and tuberculosis incidence to estimate tuberculosis incidence in 2035. Findings: Ending extreme poverty resulted in a reduction in global incidence of tuberculosis of 33·4% (95% credible interval 15·5–44·5 by 2035 and expanding social protection coverage resulted in a reduction in incidence of 76·1% (45·2–89·9 by 2035; both pathways together resulted in a reduction in incidence of 84·3% (54·7–94·9. Interpretation: Full achievement of SDG 1 could have a substantial effect on the global burden of tuberculosis. Cross-sectoral approaches that promote poverty reduction and social protection expansion will be crucial complements to health interventions, accelerating progress towards the End TB targets. Funding: World Health Organization.
Density functional theory and multiscale materials modeling
Indian Academy of Sciences (India)
One of the vital ingredients in the theoretical tools useful in materials modeling at all the length scales of interest is the concept of density. In the microscopic length scale, it is the electron density that has played a major role in providing a deeper understanding of chemical binding in atoms, molecules and solids.
Persistent Penumbra in a Rabbit Stroke Model: Incidence and Histologic Characteristics
Directory of Open Access Journals (Sweden)
Leah J. Hennings
2011-01-01
Full Text Available Duration and extent of penumbra determine the window and brain volume in which interventions may save injured tissue after stroke. Understanding the penumbra in animals is necessary in order to design models that translate to effective clinical therapies. New Zealand white rabbits were embolized with aged autologous clot (n=23 or insoluble microspheres (n=21. To examine effects of treatment on penumbra, sphere-stroked animals were treated with 3 μm microbubbles plus ultrasound (n=19. Rabbits were euthanized at 4 or 24 hr. Infarct volume was measured following triphenyltetrazolium chloride (TTC staining of brain sections. Penumbra was visualized using immunostaining of pimonidazole injected fifteen minutes prior to euthanasia. Potentially reversible penumbra was present in 14.3% stroked rabbits at 4 hours and 15.7% at 24 hours after embolic stroke and represented up to 35% of total lost tissue. Intervention at up to 24 hours may benefit a significant patient population.
International Nuclear Information System (INIS)
Donovan, E. M.; James, H.; Bonora, M.; Yarnold, J. R.; Evans, P. M.
2012-01-01
Purpose: To compare organ specific cancer incidence risks for standard and complex external beam radiotherapy (including cone beam CT verification) following breast conservation surgery for early breast cancer.Method: Doses from breast radiotherapy and kilovoltage cone beam CT (CBCT) exposures were obtained from thermoluminescent dosimeter measurements in an anthropomorphic phantom in which the positions of radiosensitive organs were delineated. Five treatment deliveries were investigated: (i) conventional tangential field whole breast radiotherapy (WBRT), (ii) noncoplanar conformal delivery applicable to accelerated partial beast irradiation (APBI), (iii) two-volume simultaneous integrated boost (SIB) treatment, (iv) forward planned three-volume SIB, and (v) inverse-planned three volume SIB. Conformal and intensity modulated radiotherapy methods were used to plan the complex treatments. Techniques spanned the range from simple methods appropriate for patient cohorts with a low cancer recurrence risk to complex plans relevant to cohorts with high recurrence risk. Delineated organs at risk included brain, salivary glands, thyroid, contralateral breast, left and right lung, esophagus, stomach, liver, colon, and bladder. Biological Effects of Ionizing Radiation (BEIR) VII cancer incidence models were applied to the measured mean organ doses to determine lifetime attributable risk (LAR) for ages at exposure from 35 to 80 yr according to radiotherapy techniques, and included dose from the CBCT imaging. Results: All LAR decreased with age at exposure and were lowest for brain, thyroid, liver, and bladder (<0.1%). There was little dependence of LAR on radiotherapy technique for these organs and for colon and stomach. LAR values for the lungs for the three SIB techniques were two to three times those from WBRT and APBI. Uncertainties in the LAR models outweigh any differences in lung LAR between the SIB methods. Constraints in the planning of the SIB methods ensured that
Pizzitutti, Francesco; Pan, William; Barbieri, Alisson; Miranda, J Jaime; Feingold, Beth; Guedes, Gilvan R; Alarcon-Valenzuela, Javiera; Mena, Carlos F
2015-12-22
The Amazon environment has been exposed in the last decades to radical changes that have been accompanied by a remarkable rise of both Plasmodium falciparum and Plasmodium vivax malaria. The malaria transmission process is highly influenced by factors such as spatial and temporal heterogeneities of the environment and individual-based characteristics of mosquitoes and humans populations. All these determinant factors can be simulated effectively trough agent-based models. This paper presents a validated agent-based model of local-scale malaria transmission. The model reproduces the environment of a typical riverine village in the northern Peruvian Amazon, where the malaria transmission is highly seasonal and apparently associated with flooding of large areas caused by the neighbouring river. Agents representing humans, mosquitoes and the two species of Plasmodium (P. falciparum and P. vivax) are simulated in a spatially explicit representation of the environment around the village. The model environment includes: climate, people houses positions and elevation. A representation of changes in the mosquito breeding areas extension caused by the river flooding is also included in the simulation environment. A calibration process was carried out to reproduce the variations of the malaria monthly incidence over a period of 3 years. The calibrated model is also able to reproduce the spatial heterogeneities of local scale malaria transmission. A "what if" eradication strategy scenario is proposed: if the mosquito breeding sites are eliminated through mosquito larva habitat management in a buffer area extended at least 200 m around the village, the malaria transmission is eradicated from the village. The use of agent-based models can reproduce effectively the spatiotemporal variations of the malaria transmission in a low endemicity environment dominated by river floodings like in the Amazon.
Local and Global Function Model of the Liver
Energy Technology Data Exchange (ETDEWEB)
Wang, Hesheng, E-mail: hesheng@umich.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Feng, Mary [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Jackson, Andrew [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Ten Haken, Randall K.; Lawrence, Theodore S. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Cao, Yue [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Department of Radiology, University of Michigan, Ann Arbor, Michigan (United States); Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan (United States)
2016-01-01
Purpose: To develop a local and global function model in the liver based on regional and organ function measurements to support individualized adaptive radiation therapy (RT). Methods and Materials: A local and global model for liver function was developed to include both functional volume and the effect of functional variation of subunits. Adopting the assumption of parallel architecture in the liver, the global function was composed of a sum of local function probabilities of subunits, varying between 0 and 1. The model was fit to 59 datasets of liver regional and organ function measures from 23 patients obtained before, during, and 1 month after RT. The local function probabilities of subunits were modeled by a sigmoid function in relating to MRI-derived portal venous perfusion values. The global function was fitted to a logarithm of an indocyanine green retention rate at 15 minutes (an overall liver function measure). Cross-validation was performed by leave-m-out tests. The model was further evaluated by fitting to the data divided according to whether the patients had hepatocellular carcinoma (HCC) or not. Results: The liver function model showed that (1) a perfusion value of 68.6 mL/(100 g · min) yielded a local function probability of 0.5; (2) the probability reached 0.9 at a perfusion value of 98 mL/(100 g · min); and (3) at a probability of 0.03 [corresponding perfusion of 38 mL/(100 g · min)] or lower, the contribution to global function was lost. Cross-validations showed that the model parameters were stable. The model fitted to the data from the patients with HCC indicated that the same amount of portal venous perfusion was translated into less local function probability than in the patients with non-HCC tumors. Conclusions: The developed liver function model could provide a means to better assess individual and regional dose-responses of hepatic functions, and provide guidance for individualized treatment planning of RT.
Predictive assessment of models for dynamic functional connectivity
DEFF Research Database (Denmark)
Nielsen, Søren Føns Vind; Schmidt, Mikkel Nørgaard; Madsen, Kristoffer Hougaard
2018-01-01
In neuroimaging, it has become evident that models of dynamic functional connectivity (dFC), which characterize how intrinsic brain organization changes over time, can provide a more detailed representation of brain function than traditional static analyses. Many dFC models in the literature...... represent functional brain networks as a meta-stable process with a discrete number of states; however, there is a lack of consensus on how to perform model selection and learn the number of states, as well as a lack of understanding of how different modeling assumptions influence the estimated state...
Theory of model Hamiltonians and method of functional integration
International Nuclear Information System (INIS)
Popov, V.N.
1990-01-01
Results on application of functional integration method to statistical physics systems with model Hamiltonians Dicke and Bardeen-Cooper-Schrieffer (BCS) are presented. Representations of statistical sums of these functional integration models are obtained. Asymptotic formulae (in N → ∞ thermodynamic range) for statistical sums of various modifications of the Dicke model as well as for the Green functions and Bose-excitations collective spectrum are exactly proved. Analogous results without exact substantiation are obtained for statistical sums and spectrum of Bose-excitations of the BCS model. 21 refs
A model of synthesis based on functional reasoning
DEFF Research Database (Denmark)
Hansen, Claus Thorp; Zavbi, R.
2002-01-01
In this paper we propose a model of how to carry out functional reasoning. The model is based on the domain theory, and it links the stepwise determination of the artefact´s characteristics during the design process to different ways of carrying out functional reasoning found in the literature....... The model proposes of a set of the mental objects and a number of ways to carry out functional reasoning available to the engineering designer. The result of the research presented in this paper is the building of a hypothesis "in the form of a model" with explanatory power....
Directory of Open Access Journals (Sweden)
Jisheng Zhang
2015-06-01
Full Text Available It is essential for transportation management centers to equip and manage a network of fixed and mobile sensors in order to quickly detect traffic incidents and further monitor the related impact areas, especially for high-impact accidents with dramatic traffic congestion propagation. As emerging small Unmanned Aerial Vehicles (UAVs start to have a more flexible regulation environment, it is critically important to fully explore the potential for of using UAVs for monitoring recurring and non-recurring traffic conditions and special events on transportation networks. This paper presents a space-time network- based modeling framework for integrated fixed and mobile sensor networks, in order to provide a rapid and systematic road traffic monitoring mechanism. By constructing a discretized space-time network to characterize not only the speed for UAVs but also the time-sensitive impact areas of traffic congestion, we formulate the problem as a linear integer programming model to minimize the detection delay cost and operational cost, subject to feasible flying route constraints. A Lagrangian relaxation solution framework is developed to decompose the original complex problem into a series of computationally efficient time-dependent and least cost path finding sub-problems. Several examples are used to demonstrate the results of proposed models in UAVs’ route planning for small and medium-scale networks.
Zhang, Jisheng; Jia, Limin; Niu, Shuyun; Zhang, Fan; Tong, Lu; Zhou, Xuesong
2015-06-12
It is essential for transportation management centers to equip and manage a network of fixed and mobile sensors in order to quickly detect traffic incidents and further monitor the related impact areas, especially for high-impact accidents with dramatic traffic congestion propagation. As emerging small Unmanned Aerial Vehicles (UAVs) start to have a more flexible regulation environment, it is critically important to fully explore the potential for of using UAVs for monitoring recurring and non-recurring traffic conditions and special events on transportation networks. This paper presents a space-time network- based modeling framework for integrated fixed and mobile sensor networks, in order to provide a rapid and systematic road traffic monitoring mechanism. By constructing a discretized space-time network to characterize not only the speed for UAVs but also the time-sensitive impact areas of traffic congestion, we formulate the problem as a linear integer programming model to minimize the detection delay cost and operational cost, subject to feasible flying route constraints. A Lagrangian relaxation solution framework is developed to decompose the original complex problem into a series of computationally efficient time-dependent and least cost path finding sub-problems. Several examples are used to demonstrate the results of proposed models in UAVs' route planning for small and medium-scale networks.
Directory of Open Access Journals (Sweden)
Bryce Morsky
2012-01-01
Full Text Available Behavior-incidence models have been used to model phenomena such as free-riding vaccinating behavior, where nonvaccinators free ride on herd immunity generated by vaccinators. Here, we develop and analyze a simulation model of voluntary ring vaccination on an evolving social contact network. Individuals make vaccination decisions by examining their expected payoffs, which are influenced by the infection status of their neighbors. We find that stochasticity can make outcomes extremely variable (near critical thresholds and thus unpredictable: some stochastic realizations result in rapid control through ring vaccination while others result in widespread transmission. We also explore the phenomenon of outcome inelasticity, wherein behavioral responses result in certain outcome measures remaining relatively unchanged. Finally, we explore examples where ineffective or risky vaccines are more widely adopted than safe, effective vaccines. This occurs when such a vaccine is unattractive to a sufficient number of contacts of an index case to cause failure of ring vaccination. As a result, the infection percolates through the entire network, causing the final epidemic size and vaccine coverage to be higher than would otherwise occur. Effects such as extreme outcome variability and outcome inelasticity have implications for vaccination policies that depend on individual choice for their success and predictability.
Modelling of functional systems of managerial accounting
Directory of Open Access Journals (Sweden)
O.V. Fomina
2017-12-01
Full Text Available The modern stage of managerial accounting development takes place under the powerful influence of managerial innovations. The article aimed at the development of integrational model of budgeting and the system of balanced indices in the system of managerial accounting that will contribute the increasing of relevance for making managerial decisions by managers of different levels management. As a result of the study the author proposed the highly pragmatical integration model of budgeting and system of the balanced indices in the system of managerial accounting, which is realized by the development of the system of gathering, consolidation, analysis, and interpretation of financial and nonfinancial information, contributes the increasing of relevance for making managerial decisions on the base of coordination and effective and purpose orientation both strategical and operative resources of an enterprise. The effective integrational process of the system components makes it possible to distribute limited resources rationally taking into account prospective purposes and strategic initiatives, to carry
Directory of Open Access Journals (Sweden)
Lianfa Li
2018-02-01
Full Text Available Abstract Background As a common infectious disease, hand, foot and mouth disease (HFMD is affected by multiple environmental and socioeconomic factors, and its pathogenesis is complex. Furthermore, the transmission of HFMD is characterized by strong spatial clustering and autocorrelation, and the classical statistical approach may be biased without consideration of spatial autocorrelation. In this paper, we propose to embed spatial characteristics into a spatiotemporal additive model to improve HFMD incidence assessment. Methods Using incidence data (6439 samples from 137 monitoring district for Shandong Province, China, along with meteorological, environmental and socioeconomic spatial and spatiotemporal covariate data, we proposed a spatiotemporal mixed model to estimate HFMD incidence. Geo-additive regression was used to model the non-linear effects of the covariates on the incidence risk of HFMD in univariate and multivariate models. Furthermore, the spatial effect was constructed to capture spatial autocorrelation at the sub-regional scale, and clusters (hotspots of high risk were generated using spatiotemporal scanning statistics as a predictor. Linear and non-linear effects were compared to illustrate the usefulness of non-linear associations. Patterns of spatial effects and clusters were explored to illustrate the variation of the HFMD incidence across geographical sub-regions. To validate our approach, 10-fold cross-validation was conducted. Results The results showed that there were significant non-linear associations of the temporal index, spatiotemporal meteorological factors and spatial environmental and socioeconomic factors with HFMD incidence. Furthermore, there were strong spatial autocorrelation and clusters for the HFMD incidence. Spatiotemporal meteorological parameters, the normalized difference vegetation index (NDVI, the temporal index, spatiotemporal clustering and spatial effects played important roles as predictors in
Functional summary statistics for the Johnson-Mehl model
DEFF Research Database (Denmark)
Møller, Jesper; Ghorbani, Mohammad
The Johnson-Mehl germination-growth model is a spatio-temporal point process model which among other things have been used for the description of neurotransmitters datasets. However, for such datasets parametric Johnson-Mehl models fitted by maximum likelihood have yet not been evaluated by means...... of functional summary statistics. This paper therefore invents four functional summary statistics adapted to the Johnson-Mehl model, with two of them based on the second-order properties and the other two on the nuclei-boundary distances for the associated Johnson-Mehl tessellation. The functional summary...... statistics theoretical properties are investigated, non-parametric estimators are suggested, and their usefulness for model checking is examined in a simulation study. The functional summary statistics are also used for checking fitted parametric Johnson-Mehl models for a neurotransmitters dataset....
Evaluation of a differentiation model of preschoolers’ executive functions
Howard, Steven J.; Okely, Anthony D.; Ellis, Yvonne G.
2015-01-01
Despite the prominent role of executive functions in children’s emerging competencies, there remains debate regarding the structure and development of executive functions. In an attempt to reconcile these discrepancies, a differentiation model of executive function development was evaluated in the early years using 6-month age groupings. Specifically, 281 preschoolers completed measures of working memory, inhibition, and shifting. Results contradicted suggestions that executive functions foll...
Evaluation of a differentiation model of preschoolers’ executive functions
Howard, Steven J.; Okely, Anthony D.; Ellis, Yvonne G.
2015-01-01
Despite the prominent role of executive functions in children’s emerging competencies, there remains debate regarding the structure and development of executive functions. In an attempt to reconcile these discrepancies, a differentiation model of executive function development was evaluated in the early years using 6-month age groupings. Specifically, 281 preschoolers completed measures of working memory, inhibition, and shifting. Results contradicted suggestions that executive functions follow a single trajectory of progressive separation in childhood, instead suggesting that these functions may undergo a period of integration in the preschool years. These results highlight potential problems with current practices and theorizing in executive function research. PMID:25852603
Evaluation of a differentiation model of preschoolers' executive functions.
Howard, Steven J; Okely, Anthony D; Ellis, Yvonne G
2015-01-01
Despite the prominent role of executive functions in children's emerging competencies, there remains debate regarding the structure and development of executive functions. In an attempt to reconcile these discrepancies, a differentiation model of executive function development was evaluated in the early years using 6-month age groupings. Specifically, 281 preschoolers completed measures of working memory, inhibition, and shifting. Results contradicted suggestions that executive functions follow a single trajectory of progressive separation in childhood, instead suggesting that these functions may undergo a period of integration in the preschool years. These results highlight potential problems with current practices and theorizing in executive function research.
Schlingermann, Brenagh E; Lodge, Clare A; Gissane, Conor; Rankin, Paula M
2017-07-05
The purpose of this Observational Analytical Cohort Study was to assess the effectiveness of an injury prevention programme (IPP) - GAA15 (Gaelic Athletic Association 15) - on the incidence of injury in collegiate Gaelic games. 131 Gaelic games players (mean age 20.5 years ± SD 3.0) were used for analysis in this study. Participants completed preseason and postseason testing which involved performance of the Y Balance test. The GAA15 was employed for the intervention group; coaches were instructed to implement the programme before every training session and match throughout the collegiate GAA (Gaelic Athletic Association) season. The control group adopted their normal warm up procedures for the season. Player's injuries were documented on a weekly basis by allied health care professionals working with the teams using an online database system. Results showed significant improvements in composite Y balance scores in favour of the intervention group (Adjusted mean difference Right: 1.8 % Normalised Mean Reach Distance (%NMRD) [p= 0.007] / Left: 2.3 %NMRD [p= 0.001]). Injury rates in the intervention group (2.62 injuries per 1000h) were reduced by 66% (p=0.001) in comparison to an age matched control group (7.62 per 1000h). Training injuries, hamstring injuries, non-contact injuries and severe injuries were also reduced as a result of the implementation of the GAA15 (Injury Rate Ratio (IRR): 0.20, 0.59, 0.39, and 0.45 respectively). Implementation of an IPP such as the GAA15 can reduce the risk of injury in Gaelic games and influence player's neuromuscular performance assessed through the Y Balance test.
Multiloop functional renormalization group for general models
Kugler, Fabian B.; von Delft, Jan
2018-02-01
We present multiloop flow equations in the functional renormalization group (fRG) framework for the four-point vertex and self-energy, formulated for a general fermionic many-body problem. This generalizes the previously introduced vertex flow [F. B. Kugler and J. von Delft, Phys. Rev. Lett. 120, 057403 (2018), 10.1103/PhysRevLett.120.057403] and provides the necessary corrections to the self-energy flow in order to complete the derivative of all diagrams involved in the truncated fRG flow. Due to its iterative one-loop structure, the multiloop flow is well suited for numerical algorithms, enabling improvement of many fRG computations. We demonstrate its equivalence to a solution of the (first-order) parquet equations in conjunction with the Schwinger-Dyson equation for the self-energy.
Shi, Changgui; Hu, Bo; Guo, Lei; Cao, Peng; Tian, Ye; Ma, Jun; Chen, Yuanyuan; Wu, Huiqiao; Hu, Jinquan; Deng, Lianfu; Zhang, Ying; Yuan, Wen
2016-05-01
Osteogenesis imperfecta (OI) is a genetic bone dysplasia characterized by brittle bones with increased fracture risk. Although current treatment options to improve bone strength in OI focus on antiresorptive bisphosphonates, controlled clinical trials suggest they have an equivocal effect on reducing fracture risk. Strontium ranelate (SrR) is a promising therapy with a dual mode of action that is capable of simultaneously maintaining bone formation and reducing bone resorption, and may be beneficial for the treatment of OI. In this study, SrR therapy was investigated to assess its effects on fracture frequency and bone mass and strength in an animal model of OI, the oim/oim mouse. Three-week-old oim/oim and wt/wt mice were treated with either SrR or vehicle (Veh) for 11 weeks. After treatment, the average number of fractures sustained by SrR-treated oim/oim mice was significantly reduced compared to Veh-treated oim/oim mice. Micro-computed tomographic (μCT) analyses of femurs showed that both trabecular and cortical bone mass were significantly improved with SrR treatment in both genotypes. SrR significantly inhibited bone resorption, whereas bone formation indices were maintained. Biomechanical testing revealed improved bone structural properties in both oim/oim and wild-type (wt/wt) mice under the treatment, whereas no significant effects on bone brittleness and material quality were observed. In conclusion, SrR was able to effectively reduce fractures in oim/oim mice by improving bone mass and strength and thus represents a potential therapy for the treatment of pediatric OI. © 2015 American Society for Bone and Mineral Research. © 2015 American Society for Bone and Mineral Research.
Afifi, Tracie O; Taillieu, Tamara; Cheung, Kristene; Katz, Laurence Y; Tonmyr, Lil; Sareen, Jitender
2015-01-01
Objective: Identifying child and household characteristics that are associated with specific child maltreatment types and child functional impairment are important for informing prevention and intervention efforts. Our objectives were to examine the distribution of several child and household characteristics among substantiated child maltreatment types in Canada; to determine if a specific child maltreatment type relative to all other types was associated with increased odds of child functional impairment; and to determine which child and household characteristics were associated with child functional impairment. Method: Data were from the Canadian Incidence Study of Reported Child Abuse and Neglect (collection 2008) from 112 child welfare sites across Canada (n = 6163 children). Results: Physical abuse, sexual abuse, and emotional maltreatment were highly prevalent among children aged 10 to 15 years. For single types of child maltreatment, the highest prevalence of single-parent homes (50.6%), social assistance (43.0%), running out of money regularly (30.7%), and unsafe housing (30.9%) were reported for substantiated cases of neglect. Being male, older age, living in a single-parent home, household running out of money, moving 2 or more times in the past year, and household overcrowding were associated with increased odds of child functional impairment. Conclusions: More work is warranted to determine if providing particular resources for single-parent families, financial counselling, and facilitating adequate and stable housing for families with child maltreatment histories or at risk for child maltreatment could be effective for improving child functional outcomes. PMID:26175390
Lee, Hsuei-Chen; Chang, Ku-Chou; Tsauo, Jau-Yih; Hung, Jen-Wen; Huang, Yu-Ching; Lin, Sang-I
2013-04-01
To evaluate effects of a multifactorial fall prevention program on fall incidence and physical function in community-dwelling older adults. Multicenter randomized controlled trial. Three medical centers and adjacent community health centers. Community-dwelling older adults (N=616) who have fallen in the previous year or are at risk of falling. After baseline assessment, eligible subjects were randomly allocated into the intervention group (IG) or the control group (CG), stratified by the Physiological Profile Assessment (PPA) fall risk level. The IG received a 3-month multifactorial intervention program including 8 weeks of exercise training, health education, home hazards evaluation/modification, along with medication review and ophthalmology/other specialty consults. The CG received health education brochures, referrals, and recommendations without direct exercise intervention. Primary outcome was fall incidence within 1 year. Secondary outcomes were PPA battery (overall fall risk index, vision, muscular strength, reaction time, balance, and proprioception), Timed Up & Go (TUG) test, Taiwan version of the International Physical Activity Questionnaire, EuroQol-5D, Geriatric Depression Scale (GDS), and the Falls Efficacy Scale-International at 3 months after randomization. Participants were 76±7 years old and included low risk 25.6%, moderate risk 25.6%, and marked risk 48.7%. The cumulative 1-year fall incidence was 25.2% in the IG and 27.6% in the CG (hazard ratio=.90; 95% confidence interval, .66-1.23). The IG improved more favorably than the CG on overall PPA fall risk index, reaction time, postural sway with eyes open, TUG test, and GDS, especially for those with marked fall risk. The multifactorial fall prevention program with exercise intervention improved functional performance at 3 months for community-dwelling older adults with risk of falls, but did not reduce falls at 1-year follow-up. Fall incidence might have been decreased simultaneously in both
Improved analyses using function datasets and statistical modeling
John S. Hogland; Nathaniel M. Anderson
2014-01-01
Raster modeling is an integral component of spatial analysis. However, conventional raster modeling techniques can require a substantial amount of processing time and storage space and have limited statistical functionality and machine learning algorithms. To address this issue, we developed a new modeling framework using C# and ArcObjects and integrated that framework...
Partition function of nearest neighbour Ising models: Some new ...
Indian Academy of Sciences (India)
Administrator
While the formula- tion of the partition function pertaining to one- dimensional nearest neighbour Ising models is pedagogical and straight-forward,. 4 the same is not true for the two-dimensional Ising models. The cele- brated solution of Onsager. 5 for the two-dimensional. Ising model at H = 0 led to the detailed analysis of.
Functional Modelling for Fault Diagnosis and its application for NPP
DEFF Research Database (Denmark)
Lind, Morten; Zhang, Xinxin
2014-01-01
The paper presents functional modelling and its application for diagnosis in nuclear power plants.Functional modelling is defined and it is relevance for coping with the complexity of diagnosis in large scale systems like nuclear plants is explained. The diagnosis task is analyzed and it is demon......The paper presents functional modelling and its application for diagnosis in nuclear power plants.Functional modelling is defined and it is relevance for coping with the complexity of diagnosis in large scale systems like nuclear plants is explained. The diagnosis task is analyzed....... The use of MFM for reasoning about causes and consequences is explained in detail and demonstrated using the reasoning tool the MFM Suite. MFM applications in nuclear power systems are described by two examples a PWR and a FBRreactor. The PWR example show how MFM can be used to model and reason about...
The basis function approach for modeling autocorrelation in ecological data.
Hefley, Trevor J; Broms, Kristin M; Brost, Brian M; Buderman, Frances E; Kay, Shannon L; Scharf, Henry R; Tipton, John R; Williams, Perry J; Hooten, Mevin B
2017-03-01
Analyzing ecological data often requires modeling the autocorrelation created by spatial and temporal processes. Many seemingly disparate statistical methods used to account for autocorrelation can be expressed as regression models that include basis functions. Basis functions also enable ecologists to modify a wide range of existing ecological models in order to account for autocorrelation, which can improve inference and predictive accuracy. Furthermore, understanding the properties of basis functions is essential for evaluating the fit of spatial or time-series models, detecting a hidden form of collinearity, and analyzing large data sets. We present important concepts and properties related to basis functions and illustrate several tools and techniques ecologists can use when modeling autocorrelation in ecological data. © 2016 by the Ecological Society of America.
Directory of Open Access Journals (Sweden)
Marcia Regina Gianotti Franco
Full Text Available Abstract Introduction: Data on impact of high body mass index (BMI on mortality of patients on peritoneal dialysis (PD, especially among elderly, are inconsistent. Objective: To evaluate impact of BMI on cohort of incident elderly PD patients over time. Methods: Prospective multicenter cohort study (December / 2004-October/2007 with 674 patients. Socio-demographic and clinical data evaluated with patients followed until death, transfer to hemodialysis (HD, recovery of renal function, loss of follow-up or transplant. Patients were divided into incident on renal replacement therapy (RRT for PD (PD first: 230 and transferred from hemodialysis (HD first: 444. Analysis was performed comparing these two groups using chi-square or Kruskal Wallis. Similar analysis was used to compare patients on automated peritoneal dialysis (APD vs. continuous ambulatory peritoneal dialysis (CAPD. Data were compared between patients according to BMI by ANOVA, Kruskal Wallis or chi-square. For analysis of survival, Kaplan Meier method was used and to adjust confounding variables, Cox regression proportional hazard. Joint model for longitudinal and time-dependent data was conducted, assessing impact that a longitudinal variable displays on time of survival. Results: Malnourished patients (76.79 ± 7.53 years were older (p < 0.0001 with higher percentage of death (44.6%, p = 0.001; diabetes mellitus showed high prevalence in obese patients (68%, p < 0.0001; higher blood pressure levels (p = 0.002 were present in obese and overweight patients. Conclusions: Increased BMI variation over time proved to be a protective factor, with a decrease of about 1% in risk of death for every BMI unit earned.
Deep inelastic structure functions in the chiral bag model
Energy Technology Data Exchange (ETDEWEB)
Sanjose, V. (Valencia Univ. (Spain). Dept. de Didactica de las Ciencias Experimentales); Vento, V. (Valencia Univ. (Spain). Dept. de Fisica Teorica; Centro Mixto CSIC/Valencia Univ., Valencia (Spain). Inst. de Fisica Corpuscular)
1989-10-02
We calculate the structure functions for deep inelastic scattering on baryons in the cavity approximation to the chiral bag model. The behavior of these structure functions is analyzed in the Bjorken limit. We conclude that scaling is satisfied, but not Regge behavior. A trivial extension as a parton model can be achieved by introducing the structure function for the pion in a convolution picture. In this extended version of the model not only scaling but also Regge behavior is satisfied. Conclusions are drawn from the comparison of our results with experimental data. (orig.).
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
Functional Characterization of a Porcine Emphysema Model
DEFF Research Database (Denmark)
Bruun, Camilla Sichlau; Jensen, Louise Kruse; Leifsson, Páll Skuli
2013-01-01
phenotypes in humans. Also, the catalytic activities of metalloproteinases (MMPs) are central in the pathogenesis of emphysema/COPD. Especially MMP9, but also MMP2, MMP7, and MMP12 seem to be involved in human emphysema. MMP12−/− mice are protected from smoke-induced emphysema. ITGB6−/− mice spontaneously...... the expression of MMP2, MMP7, MMP9, MMP12, and TGF-β1 by quantitative PCR (qPCR). In addition, immunohistochemical stainings of the lungs with SP-B, SP-C, MMP9, and MMP12 antibodies were performed. The haematologic/immunologic status of the pigs also was studied.The qPCR study showed no difference between pigs...... develop age-related lung emphysema due to lack of ITGB6-TGF-β1 regulation of the MMP12 expression.A mutated pig phenotype characterized by age-related lung emphysema and resembling the ITGB6−/− mouse has been described previously. To investigate the emphysema pathogenesis in this pig model, we examined...
BioModels: Content, Features, Functionality, and Use
Juty, N; Ali, R; Glont, M; Keating, S; Rodriguez, N; Swat, MJ; Wimalaratne, SM; Hermjakob, H; Le Novère, N; Laibe, C; Chelliah, V
2015-01-01
BioModels is a reference repository hosting mathematical models that describe the dynamic interactions of biological components at various scales. The resource provides access to over 1,200 models described in literature and over 140,000 models automatically generated from pathway resources. Most model components are cross-linked with external resources to facilitate interoperability. A large proportion of models are manually curated to ensure reproducibility of simulation results. This tutorial presents BioModels' content, features, functionality, and usage. PMID:26225232
Beretvas, S. Natasha; Walker, Cindy M.
2012-01-01
This study extends the multilevel measurement model to handle testlet-based dependencies. A flexible two-level testlet response model (the MMMT-2 model) for dichotomous items is introduced that permits assessment of differential testlet functioning (DTLF). A distinction is made between this study's conceptualization of DTLF and that of…
Multinomial-exponential reliability function: a software reliability model
International Nuclear Information System (INIS)
Saiz de Bustamante, Amalio; Saiz de Bustamante, Barbara
2003-01-01
The multinomial-exponential reliability function (MERF) was developed during a detailed study of the software failure/correction processes. Later on MERF was approximated by a much simpler exponential reliability function (EARF), which keeps most of MERF mathematical properties, so the two functions together makes up a single reliability model. The reliability model MERF/EARF considers the software failure process as a non-homogeneous Poisson process (NHPP), and the repair (correction) process, a multinomial distribution. The model supposes that both processes are statistically independent. The paper discusses the model's theoretical basis, its mathematical properties and its application to software reliability. Nevertheless it is foreseen model applications to inspection and maintenance of physical systems. The paper includes a complete numerical example of the model application to a software reliability analysis
Schechter, Clyde B; Near, Aimee M; Jayasekera, Jinani; Chandler, Young; Mandelblatt, Jeanne S
2018-04-01
The Georgetown University-Albert Einstein College of Medicine breast cancer simulation model (Model GE) has evolved over time in structure and function to reflect advances in knowledge about breast cancer, improvements in early detection and treatment technology, and progress in computing resources. This article describes the model and provides examples of model applications. The model is a discrete events microsimulation of single-life histories of women from multiple birth cohorts. Events are simulated in the absence of screening and treatment, and interventions are then applied to assess their impact on population breast cancer trends. The model accommodates differences in natural history associated with estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) biomarkers, as well as conventional breast cancer risk factors. The approach for simulating breast cancer natural history is phenomenological, relying on dates, stage, and age of clinical and screen detection for a tumor molecular subtype without explicitly modeling tumor growth. The inputs to the model are regularly updated to reflect current practice. Numerous technical modifications, including the use of object-oriented programming (C++), and more efficient algorithms, along with hardware advances, have increased program efficiency permitting simulations of large samples. The model results consistently match key temporal trends in US breast cancer incidence and mortality. The model has been used in collaboration with other CISNET models to assess cancer control policies and will be applied to evaluate clinical trial design, recurrence risk, and polygenic risk-based screening.
Smalley, Hannah K; Keskinocak, Pinar; Swann, Julie; Hinman, Alan
2015-11-17
In addition to improved sanitation, hygiene, and better access to safe water, oral cholera vaccines can help to control the spread of cholera in the short term. However, there is currently no systematic method for determining the best allocation of oral cholera vaccines to minimize disease incidence in a population where the disease is endemic and resources are limited. We present a mathematical model for optimally allocating vaccines in a region under varying levels of demographic and incidence data availability. The model addresses the questions of where, when, and how many doses of vaccines to send. Considering vaccine efficacies (which may vary based on age and the number of years since vaccination), we analyze distribution strategies which allocate vaccines over multiple years. Results indicate that, given appropriate surveillance data, targeting age groups and regions with the highest disease incidence should be the first priority, followed by other groups primarily in order of disease incidence, as this approach is the most life-saving and cost-effective. A lack of detailed incidence data results in distribution strategies which are not cost-effective and can lead to thousands more deaths from the disease. The mathematical model allows for what-if analysis for various vaccine distribution strategies by providing the ability to easily vary parameters such as numbers and sizes of regions and age groups, risk levels, vaccine price, vaccine efficacy, production capacity and budget. Copyright © 2015 Elsevier Ltd. All rights reserved.
Computational Models for Calcium-Mediated Astrocyte Functions
Directory of Open Access Journals (Sweden)
Tiina Manninen
2018-04-01
Full Text Available The computational neuroscience field has heavily concentrated on the modeling of neuronal functions, largely ignoring other brain cells, including one type of glial cell, the astrocytes. Despite the short history of modeling astrocytic functions, we were delighted about the hundreds of models developed so far to study the role of astrocytes, most often in calcium dynamics, synchronization, information transfer, and plasticity in vitro, but also in vascular events, hyperexcitability, and homeostasis. Our goal here is to present the state-of-the-art in computational modeling of astrocytes in order to facilitate better understanding of the functions and dynamics of astrocytes in the brain. Due to the large number of models, we concentrated on a hundred models that include biophysical descriptions for calcium signaling and dynamics in astrocytes. We categorized the models into four groups: single astrocyte models, astrocyte network models, neuron-astrocyte synapse models, and neuron-astrocyte network models to ease their use in future modeling projects. We characterized the models based on which earlier models were used for building the models and which type of biological entities were described in the astrocyte models. Features of the models were compared and contrasted so that similarities and differences were more readily apparent. We discovered that most of the models were basically generated from a small set of previously published models with small variations. However, neither citations to all the previous models with similar core structure nor explanations of what was built on top of the previous models were provided, which made it possible, in some cases, to have the same models published several times without an explicit intention to make new predictions about the roles of astrocytes in brain functions. Furthermore, only a few of the models are available online which makes it difficult to reproduce the simulation results and further develop
Directory of Open Access Journals (Sweden)
Jie Lou
Full Text Available To project the HIV/AIDS epidemics among men who have sex with men (MSM under different combinations of HIV testing and linkage to care (TLC interventions including antiretroviral therapy (ART in Beijing, China.Mathematical modeling.Using a mathematical model to fit prevalence estimates from 2000-2010, we projected trends in HIV prevalence and incidence during 2011-2020 under five scenarios: (S1 current intervention levels by averaging 2000-2010 coverage; (S2 increased ART coverage with current TLC; (S3 increased TLC/ART coverage; (S4 increased condom use; and (S5 increased TLC/ART plus increased condom use.The basic reproduction number based upon the current level of interventions is significantly higher than 1 (R0 = 2.09; 95% confidence interval (CI, 1.83-2.35, suggesting that the HIV epidemic will continue to increase to 2020. Compared to the 2010 prevalence of 7.8%, the projected HIV prevalence in 2020 for the five prevention scenarios will be: (S1 Current coverage: 21.4% (95% CI, 9.9-31.7%; (S2 Increased ART: 19.9% (95% CI, 9.9-28.4%; (S3 Increased TLC/ART: 14.5% (95% CI, 7.0-23.8%; (S4 Increased condom use: 13.0% (95% CI, 9.8-28.4%; and (S5 Increased TLC/ART and condom use: 8.7% (95% CI, 5.4-11.5%. HIV epidemic will continue to rise (R0 > 1 for S1-S4 even with hyperbolic coverage in the sensitivity analysis, and is expected to decline (R0 = 0.93 for S5.Our transmission model suggests that Beijing MSM will have a rapidly rising HIV epidemic. Even enhanced levels of TLC/ART will not interrupt epidemic expansion, despite optimistic assumptions for coverage. Promoting condom use is a crucial component of combination interventions.
Lou, Jie; Blevins, Meridith; Ruan, Yuhua; Vermund, Sten H; Tang, Sanyi; Webb, Glenn F; Shepherd, Bryan E; He, Xiong; Lu, Hongyan; Shao, Yiming; Qian, Han-Zhu
2014-01-01
To project the HIV/AIDS epidemics among men who have sex with men (MSM) under different combinations of HIV testing and linkage to care (TLC) interventions including antiretroviral therapy (ART) in Beijing, China. Mathematical modeling. Using a mathematical model to fit prevalence estimates from 2000-2010, we projected trends in HIV prevalence and incidence during 2011-2020 under five scenarios: (S1) current intervention levels by averaging 2000-2010 coverage; (S2) increased ART coverage with current TLC; (S3) increased TLC/ART coverage; (S4) increased condom use; and (S5) increased TLC/ART plus increased condom use. The basic reproduction number based upon the current level of interventions is significantly higher than 1 (R0 = 2.09; 95% confidence interval (CI), 1.83-2.35), suggesting that the HIV epidemic will continue to increase to 2020. Compared to the 2010 prevalence of 7.8%, the projected HIV prevalence in 2020 for the five prevention scenarios will be: (S1) Current coverage: 21.4% (95% CI, 9.9-31.7%); (S2) Increased ART: 19.9% (95% CI, 9.9-28.4%); (S3) Increased TLC/ART: 14.5% (95% CI, 7.0-23.8%); (S4) Increased condom use: 13.0% (95% CI, 9.8-28.4%); and (S5) Increased TLC/ART and condom use: 8.7% (95% CI, 5.4-11.5%). HIV epidemic will continue to rise (R0 > 1) for S1-S4 even with hyperbolic coverage in the sensitivity analysis, and is expected to decline (R0 = 0.93) for S5. Our transmission model suggests that Beijing MSM will have a rapidly rising HIV epidemic. Even enhanced levels of TLC/ART will not interrupt epidemic expansion, despite optimistic assumptions for coverage. Promoting condom use is a crucial component of combination interventions.
Importance of predictor variables for models of chemical function
U.S. Environmental Protection Agency — Importance of random forest predictors for all classification models of chemical function. This dataset is associated with the following publication: Isaacs , K., M....
Commonsense Psychology and the Functional Requirements of Cognitive Models
National Research Council Canada - National Science Library
Gordon, Andrew S
2005-01-01
In this paper we argue that previous models of cognitive abilities (e.g. memory, analogy) have been constructed to satisfy functional requirements of implicit commonsense psychological theories held by researchers and nonresearchers alike...
Applying Functional Modeling for Accident Management of Nuclear Power Plant
DEFF Research Database (Denmark)
Lind, Morten; Zhang, Xinxin
2014-01-01
The paper investigate applications of functional modeling for accident management in complex industrial plant with special reference to nuclear power production. Main applications for information sharing among decision makers and decision support are identified. An overview of Multilevel Flow...
Applying Functional Modeling for Accident Management of Nucler Power Plant
DEFF Research Database (Denmark)
Lind, Morten; Zhang, Xinxin
2014-01-01
The paper investigates applications of functional modeling for accident management in complex industrial plant with special reference to nuclear power production. Main applications for information sharing among decision makers and decision support are identified. An overview of Multilevel Flow...
FUNCTIONAL MODELLING FOR FAULT DIAGNOSIS AND ITS APPLICATION FOR NPP
Directory of Open Access Journals (Sweden)
MORTEN LIND
2014-12-01
Full Text Available The paper presents functional modelling and its application for diagnosis in nuclear power plants. Functional modelling is defined and its relevance for coping with the complexity of diagnosis in large scale systems like nuclear plants is explained. The diagnosis task is analyzed and it is demonstrated that the levels of abstraction in models for diagnosis must reflect plant knowledge about goals and functions which is represented in functional modelling. Multilevel flow modelling (MFM, which is a method for functional modelling, is introduced briefly and illustrated with a cooling system example. The use of MFM for reasoning about causes and consequences is explained in detail and demonstrated using the reasoning tool, the MFMSuite. MFM applications in nuclear power systems are described by two examples: a PWR; and an FBR reactor. The PWR example show how MFM can be used to model and reason about operating modes. The FBR example illustrates how the modelling development effort can be managed by proper strategies including decomposition and reuse.
Critical incident stress management.
Lim, J J; Childs, J; Gonsalves, K
2000-10-01
Recent studies have indicated implementation of the CISM Program has impacted and reduced the cost of workers' compensation claims for stress related conditions and the number of lost work days (Ott, 1997; Western Management Consultants, 1996). Occupational health professionals need to be ready to develop and implement a comprehensive critical incident stress management process in anticipation of a major event. The ability to organize, lead, or administer critical incident stress debriefings for affected employees is a key role for the occupational health professional. Familiarity with these concepts and the ability to identify a critical incident enhances value to the business by mitigating the stress and impact to the workplace. Critical Incident Stress Management Systems have the potential for decreasing stress and restoring employees to normal life function--a win/win situation for both the employees and the organization.
Global sensitivity analysis of computer models with functional inputs
International Nuclear Information System (INIS)
Iooss, Bertrand; Ribatet, Mathieu
2009-01-01
Global sensitivity analysis is used to quantify the influence of uncertain model inputs on the response variability of a numerical model. The common quantitative methods are appropriate with computer codes having scalar model inputs. This paper aims at illustrating different variance-based sensitivity analysis techniques, based on the so-called Sobol's indices, when some model inputs are functional, such as stochastic processes or random spatial fields. In this work, we focus on large cpu time computer codes which need a preliminary metamodeling step before performing the sensitivity analysis. We propose the use of the joint modeling approach, i.e., modeling simultaneously the mean and the dispersion of the code outputs using two interlinked generalized linear models (GLMs) or generalized additive models (GAMs). The 'mean model' allows to estimate the sensitivity indices of each scalar model inputs, while the 'dispersion model' allows to derive the total sensitivity index of the functional model inputs. The proposed approach is compared to some classical sensitivity analysis methodologies on an analytical function. Lastly, the new methodology is applied to an industrial computer code that simulates the nuclear fuel irradiation.
Generalized Functional Linear Models With Semiparametric Single-Index Interactions
Li, Yehua
2010-06-01
We introduce a new class of functional generalized linear models, where the response is a scalar and some of the covariates are functional. We assume that the response depends on multiple covariates, a finite number of latent features in the functional predictor, and interaction between the two. To achieve parsimony, the interaction between the multiple covariates and the functional predictor is modeled semiparametrically with a single-index structure. We propose a two step estimation procedure based on local estimating equations, and investigate two situations: (a) when the basis functions are pre-determined, e.g., Fourier or wavelet basis functions and the functional features of interest are known; and (b) when the basis functions are data driven, such as with functional principal components. Asymptotic properties are developed. Notably, we show that when the functional features are data driven, the parameter estimates have an increased asymptotic variance, due to the estimation error of the basis functions. Our methods are illustrated with a simulation study and applied to an empirical data set, where a previously unknown interaction is detected. Technical proofs of our theoretical results are provided in the online supplemental materials.
A no extensive statistical model for the nucleon structure function
Energy Technology Data Exchange (ETDEWEB)
Trevisan, Luis A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Mirez, Carlos [Instituto de Ciencia, Engenharia e Tecnologia - ICET, Universidade Federal dos Vales do Jequitinhonha e Mucuri - UFVJM, Campus do Mucuri, Rua do Cruzeiro 01, Jardim Sao Paulo, 39803-371, Teofilo Otoni, Minas Gerais (Brazil)
2013-03-25
We studied an application of nonextensive thermodynamics to describe the structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and two chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon.
How to use COSMIC Functional Size in Effort Estimation Models?
Gencel, Cigdem
2008-01-01
Although Functional Size Measurement (FSM) methods have become widely used by the software organizations, the functional size based effort estimation still needs further investigation. Most of the studies on effort estimation consider total functional size of the software as the primary input to estimation models and they mostly focus on identifying the project parameters which might have a significant effect on the size-effort relationship. This study brings suggestions on how to use COSMIC ...
Improved Wave-vessel Transfer Functions by Uncertainty Modelling
DEFF Research Database (Denmark)
Nielsen, Ulrik Dam; Fønss Bach, Kasper; Iseki, Toshio
2016-01-01
This paper deals with uncertainty modelling of wave-vessel transfer functions used to calculate or predict wave-induced responses of a ship in a seaway. Although transfer functions, in theory, can be calculated to exactly reflect the behaviour of the ship when exposed to waves, uncertainty in input...
Optimisation of Transfer Function Models using Genetic Algorithms ...
African Journals Online (AJOL)
In order to obtain an optimum transfer function estimate, open source software based on genetic algorithm was developed. The software was developed with Visual Basic programming language. In order to test the software, a transfer function model was developed from data obtained from industry. The forecast obtained ...
International Nuclear Information System (INIS)
Dapor, Maurizio
2005-01-01
Carbon films are deposited on various substrates (polymers, polyester fabrics, polyester yarns, metal alloys) both for experimental and technological motivations (medical devices, biocompatible coatings, food package and so on). Computational studies of the penetration of electron beams in supported thin film of carbon are very useful in order to compare the simulated results with analytical techniques data (obtained by scanning electron microscopy and/or Auger electron spectroscopy) and investigate the film characteristics. In the present paper, the few keV electron depth distribution and backscattering coefficient for the special case of film of carbon deposited on aluminium are investigated, by a Monte Carlo simulation, as a function of the incidence angle and primary electron energy. The simulated results can be used as a way to evaluate the carbon film thickness by a set of measurements of the backscattering coefficient
Features of Functioning the Integrated Building Thermal Model
Directory of Open Access Journals (Sweden)
Morozov Maxim N.
2017-01-01
Full Text Available A model of the building heating system, consisting of energy source, a distributed automatic control system, elements of individual heating unit and heating system is designed. Application Simulink of mathematical package Matlab is selected as a platform for the model. There are the specialized application Simscape libraries in aggregate with a wide range of Matlab mathematical tools allow to apply the “acausal” modeling concept. Implementation the “physical” representation of the object model gave improving the accuracy of the models. Principle of operation and features of the functioning of the thermal model is described. The investigations of building cooling dynamics were carried out.
Asymptotic Optimality of Estimating Function Estimator for CHARN Model
Directory of Open Access Journals (Sweden)
Tomoyuki Amano
2012-01-01
Full Text Available CHARN model is a famous and important model in the finance, which includes many financial time series models and can be assumed as the return processes of assets. One of the most fundamental estimators for financial time series models is the conditional least squares (CL estimator. However, recently, it was shown that the optimal estimating function estimator (G estimator is better than CL estimator for some time series models in the sense of efficiency. In this paper, we examine efficiencies of CL and G estimators for CHARN model and derive the condition that G estimator is asymptotically optimal.
Cost damping and functional form in transport models
DEFF Research Database (Denmark)
Rich, Jeppe; Mabit, Stefan Lindhard
2016-01-01
take different forms and be represented as a non-linear-in-parameter form such as the well-known Box–Cox function. However, it could also be specified as non-linear-in-cost but linear-in-parameter forms, which are easier to estimate and improve model fit without increasing the number of parameters....... The specific contributions of the paper are as follows. Firstly, we discuss the phenomenon of cost damping in details and specifically why it occurs. Secondly, we provide a test of damping and an easy assessment of the (linear) damping rate for any variable by estimating two auxiliary linear models. This turns......Transport models allowing for cost damping are characterised by marginally decreasing cost sensitivities in demand. As a result, cost damping is a model extension of the simple linear-in-cost model requiring an appropriate non-linear link function between utility and cost. The link function may...
Directory of Open Access Journals (Sweden)
Wudi Wei
Full Text Available Hepatitis is a serious public health problem with increasing cases and property damage in Heng County. It is necessary to develop a model to predict the hepatitis epidemic that could be useful for preventing this disease.The autoregressive integrated moving average (ARIMA model and the generalized regression neural network (GRNN model were used to fit the incidence data from the Heng County CDC (Center for Disease Control and Prevention from January 2005 to December 2012. Then, the ARIMA-GRNN hybrid model was developed. The incidence data from January 2013 to December 2013 were used to validate the models. Several parameters, including mean absolute error (MAE, root mean square error (RMSE, mean absolute percentage error (MAPE and mean square error (MSE, were used to compare the performance among the three models.The morbidity of hepatitis from Jan 2005 to Dec 2012 has seasonal variation and slightly rising trend. The ARIMA(0,1,2(1,1,112 model was the most appropriate one with the residual test showing a white noise sequence. The smoothing factor of the basic GRNN model and the combined model was 1.8 and 0.07, respectively. The four parameters of the hybrid model were lower than those of the two single models in the validation. The parameters values of the GRNN model were the lowest in the fitting of the three models.The hybrid ARIMA-GRNN model showed better hepatitis incidence forecasting in Heng County than the single ARIMA model and the basic GRNN model. It is a potential decision-supportive tool for controlling hepatitis in Heng County.
Wei, Wudi; Jiang, Junjun; Liang, Hao; Gao, Lian; Liang, Bingyu; Huang, Jiegang; Zang, Ning; Liao, Yanyan; Yu, Jun; Lai, Jingzhen; Qin, Fengxiang; Su, Jinming; Ye, Li; Chen, Hui
2016-01-01
Hepatitis is a serious public health problem with increasing cases and property damage in Heng County. It is necessary to develop a model to predict the hepatitis epidemic that could be useful for preventing this disease. The autoregressive integrated moving average (ARIMA) model and the generalized regression neural network (GRNN) model were used to fit the incidence data from the Heng County CDC (Center for Disease Control and Prevention) from January 2005 to December 2012. Then, the ARIMA-GRNN hybrid model was developed. The incidence data from January 2013 to December 2013 were used to validate the models. Several parameters, including mean absolute error (MAE), root mean square error (RMSE), mean absolute percentage error (MAPE) and mean square error (MSE), were used to compare the performance among the three models. The morbidity of hepatitis from Jan 2005 to Dec 2012 has seasonal variation and slightly rising trend. The ARIMA(0,1,2)(1,1,1)12 model was the most appropriate one with the residual test showing a white noise sequence. The smoothing factor of the basic GRNN model and the combined model was 1.8 and 0.07, respectively. The four parameters of the hybrid model were lower than those of the two single models in the validation. The parameters values of the GRNN model were the lowest in the fitting of the three models. The hybrid ARIMA-GRNN model showed better hepatitis incidence forecasting in Heng County than the single ARIMA model and the basic GRNN model. It is a potential decision-supportive tool for controlling hepatitis in Heng County.
Directory of Open Access Journals (Sweden)
Nele Goeyvaerts
2015-12-01
Full Text Available Dynamic transmission models are essential to design and evaluate control strategies for airborne infections. Our objective was to develop a dynamic transmission model for seasonal influenza allowing to evaluate the impact of vaccinating specific age groups on the incidence of infection, disease and mortality. Projections based on such models heavily rely on assumed ‘input’ parameter values. In previous seasonal influenza models, these parameter values were commonly chosen ad hoc, ignoring between-season variability and without formal model validation or sensitivity analyses. We propose to directly estimate the parameters by fitting the model to age-specific influenza-like illness (ILI incidence data over multiple influenza seasons. We used a weighted least squares (WLS criterion to assess model fit and applied our method to Belgian ILI data over six influenza seasons. After exploring parameter importance using symbolic regression, we evaluated a set of candidate models of differing complexity according to the number of season-specific parameters. The transmission parameters (average R0, seasonal amplitude and timing of the seasonal peak, waning rates and the scale factor used for WLS optimization, influenced the fit to the observed ILI incidence the most. Our results demonstrate the importance of between-season variability in influenza transmission and our estimates are in line with the classification of influenza seasons according to intensity and vaccine matching.
Likelihood functions for state space models with diffuse initial conditions
Koopman, S.J.; Shephard, N.; de Vos, A.F.
2010-01-01
State space models with non-stationary processes and/or fixed regression effects require a state vector with diffuse initial conditions. Different likelihood functions can be adopted for the estimation of parameters in time-series models with diffuse initial conditions. In this article, we consider
Likelihood functions for state space models with diffuse initial conditions
Francke, M.K.; Koopmans, S.J.; de Vos, A.F.
2008-01-01
State space models with nonstationary processes and fixed regression effects require a state vector with diffuse initial conditions. Different likelihood functions can be adopted for the estimation of parameters in time series models with diffuse initial conditions. In this paper we consider
Invention software support by integrating function and mathematical modeling
Chechurin, L.S.; Wits, Wessel Willems; Bakker, H.M.
2015-01-01
New idea generation is imperative for successful product innovation and technology development. This paper presents the development of a novel type of invention support software. The support tool integrates both function modeling and mathematical modeling, thereby enabling quantitative analyses on a
Predictive assessment of models for dynamic functional connectivity.
Nielsen, Søren F V; Schmidt, Mikkel N; Madsen, Kristoffer H; Mørup, Morten
2018-05-01
In neuroimaging, it has become evident that models of dynamic functional connectivity (dFC), which characterize how intrinsic brain organization changes over time, can provide a more detailed representation of brain function than traditional static analyses. Many dFC models in the literature represent functional brain networks as a meta-stable process with a discrete number of states; however, there is a lack of consensus on how to perform model selection and learn the number of states, as well as a lack of understanding of how different modeling assumptions influence the estimated state dynamics. To address these issues, we consider a predictive likelihood approach to model assessment, where models are evaluated based on their predictive performance on held-out test data. Examining several prominent models of dFC (in their probabilistic formulations) we demonstrate our framework on synthetic data, and apply it on two real-world examples: a face recognition EEG experiment and resting-state fMRI. Our results evidence that both EEG and fMRI are better characterized using dynamic modeling approaches than by their static counterparts, but we also demonstrate that one must be cautious when interpreting dFC because parameter settings and modeling assumptions, such as window lengths and emission models, can have a large impact on the estimated states and consequently on the interpretation of the brain dynamics. Copyright © 2018 Elsevier Inc. All rights reserved.
Density Functional Theory and Materials Modeling at Atomistic Length Scales
Directory of Open Access Journals (Sweden)
Swapan K. Ghosh
2002-04-01
Full Text Available Abstract: We discuss the basic concepts of density functional theory (DFT as applied to materials modeling in the microscopic, mesoscopic and macroscopic length scales. The picture that emerges is that of a single unified framework for the study of both quantum and classical systems. While for quantum DFT, the central equation is a one-particle Schrodinger-like Kohn-Sham equation, the classical DFT consists of Boltzmann type distributions, both corresponding to a system of noninteracting particles in the field of a density-dependent effective potential, the exact functional form of which is unknown. One therefore approximates the exchange-correlation potential for quantum systems and the excess free energy density functional or the direct correlation functions for classical systems. Illustrative applications of quantum DFT to microscopic modeling of molecular interaction and that of classical DFT to a mesoscopic modeling of soft condensed matter systems are highlighted.
Greuter, Marjolein J. E.; Demirel, Erhan; Lew, Jie-Bin; Berkhof, Johannes; Xu, Xiang-Ming; Canfell, Karen; Dekker, Evelien; Meijer, Gerrit A.; Coupé, Veerle M. H.
2016-01-01
We aimed to predict the long-term colorectal cancer incidence, mortality, and colonoscopy demand of the recently implemented Dutch colorectal cancer screening program. The Adenoma and Serrated pathway to Colorectal Cancer model was set up to simulate the Dutch screening program consisting of
Model Penentuan Nilai Target Functional Requirement Berbasis Utilitas
Directory of Open Access Journals (Sweden)
Cucuk Nur Rosyidi
2012-01-01
Full Text Available In a product design and development process, a designer faces a problem to decide functional requirement (FR target values. That decision is made under a risk since it is conducted in the early design phase using incomplete information. Utility function can be used to reflect the decision maker attitude towards the risk in making such decision. In this research, we develop a utility-based model to determine FR target values using quadratic utility function and information from Quality Function Deployment (QFD. A pencil design is used as a numerical example using quadratic utility function for each FR. The model can be applied for balancing customer and designer interest in determining FR target values.
Evaluation-Function-based Model-free Adaptive Fuzzy Control
Directory of Open Access Journals (Sweden)
Agus Naba
2016-12-01
Full Text Available Designs of adaptive fuzzy controllers (AFC are commonly based on the Lyapunov approach, which requires a known model of the controlled plant. They need to consider a Lyapunov function candidate as an evaluation function to be minimized. In this study these drawbacks were handled by designing a model-free adaptive fuzzy controller (MFAFC using an approximate evaluation function defined in terms of the current state, the next state, and the control action. MFAFC considers the approximate evaluation function as an evaluative control performance measure similar to the state-action value function in reinforcement learning. The simulation results of applying MFAFC to the inverted pendulum benchmark veriﬁed the proposed scheme’s efficacy.
The barrier function of organotypic non-melanoma skin cancer models.
Zoschke, Christian; Ulrich, Martina; Sochorová, Michaela; Wolff, Christopher; Vávrová, Kateřina; Ma, Nan; Ulrich, Claas; Brandner, Johanna M; Schäfer-Korting, Monika
2016-07-10
Non-melanoma skin cancer (NMSC) is the most frequent human cancer with continuously rising incidences worldwide. Herein, we investigated the molecular basis for the impaired skin barrier function of organotypic NMSC models. We unraveled disturbed epidermal differentiation by reflectance confocal microscopy and histopathological evaluation. While the presence of claudin-4 and occludin were distinctly reduced, zonula occludens protein-1 was more wide-spread, and claudin-1 was heterogeneously distributed within the NMSC models compared with normal reconstructed human skin. Moreover, the cancer altered stratum corneum lipid packing and profile with decreased cholesterol content, increased phospholipid amount, and altered ceramide subclasses. These alterations contributed to increased surface pH and to 1.5 to 2.6-fold enhanced caffeine permeability of the NMSC models. Three topical applications of ingenol mebutate gel (0.015%) caused abundant epidermal cell necrosis, decreased Ki-67 indices, and increased lactate dehydrogenase activity. Taken together, our study provides new biological insights into the microenvironment of organotypic NMSC models, improves the understanding of the disease model by revealing causes for impaired skin barrier function in NMSC models at the molecular level, and fosters human cell-based approaches in preclinical drug evaluation. Copyright © 2016 Elsevier B.V. All rights reserved.
Modelling the Impact of Soil Management on Soil Functions
Vogel, H. J.; Weller, U.; Rabot, E.; Stößel, B.; Lang, B.; Wiesmeier, M.; Urbanski, L.; Wollschläger, U.
2017-12-01
Due to an increasing soil loss and an increasing demand for food and energy there is an enormous pressure on soils as the central resource for agricultural production. Besides the importance of soils for biomass production there are other essential soil functions, i.e. filter and buffer for water, carbon sequestration, provision and recycling of nutrients, and habitat for biological activity. All these functions have a direct feed back to biogeochemical cycles and climate. To render agricultural production efficient and sustainable we need to develop model tools that are capable to predict quantitatively the impact of a multitude of management measures on these soil functions. These functions are considered as emergent properties produced by soils as complex systems. The major challenge is to handle the multitude of physical, chemical and biological processes interacting in a non-linear manner. A large number of validated models for specific soil processes are available. However, it is not possible to simulate soil functions by coupling all the relevant processes at the detailed (i.e. molecular) level where they are well understood. A new systems perspective is required to evaluate the ensemble of soil functions and their sensitivity to external forcing. Another challenge is that soils are spatially heterogeneous systems by nature. Soil processes are highly dependent on the local soil properties and, hence, any model to predict soil functions needs to account for the site-specific conditions. For upscaling towards regional scales the spatial distribution of functional soil types need to be taken into account. We propose a new systemic model approach based on a thorough analysis of the interactions between physical, chemical and biological processes considering their site-specific characteristics. It is demonstrated for the example of soil compaction and the recovery of soil structure, water capacity and carbon stocks as a result of plant growth and biological
Nonparametric modeling of dynamic functional connectivity in fmri data
DEFF Research Database (Denmark)
Nielsen, Søren Føns Vind; Madsen, Kristoffer H.; Røge, Rasmus
2015-01-01
dynamic changes. The existing approaches modeling dynamic connectivity have primarily been based on time-windowing the data and k-means clustering. We propose a nonparametric generative model for dynamic FC in fMRI that does not rely on specifying window lengths and number of dynamic states. Rooted......Dynamic functional connectivity (FC) has in recent years become a topic of interest in the neuroimaging community. Several models and methods exist for both functional magnetic resonance imaging (fMRI) and electroencephalography (EEG), and the results point towards the conclusion that FC exhibits...... in Bayesian statistical modeling we use the predictive likelihood to investigate if the model can discriminate between a motor task and rest both within and across subjects. We further investigate what drives dynamic states using the model on the entire data collated across subjects and task/rest. We find...
Partially linear varying coefficient models stratified by a functional covariate
Maity, Arnab
2012-10-01
We consider the problem of estimation in semiparametric varying coefficient models where the covariate modifying the varying coefficients is functional and is modeled nonparametrically. We develop a kernel-based estimator of the nonparametric component and a profiling estimator of the parametric component of the model and derive their asymptotic properties. Specifically, we show the consistency of the nonparametric functional estimates and derive the asymptotic expansion of the estimates of the parametric component. We illustrate the performance of our methodology using a simulation study and a real data application.
Energy Technology Data Exchange (ETDEWEB)
Giles, GE
2005-02-03
The purpose of this Workshop on ''Functional Requirements for the Modeling of Fate and Transport of Waterborne CBRN Materials'' was to solicit functional requirements for tools that help Incident Managers plan for and deal with the consequences of industrial or terrorist releases of materials into the nation's waterways and public water utilities. Twenty representatives attended and several made presentations. Several hours of discussions elicited a set of requirements. These requirements were summarized in a form for the attendees to vote on their highest priority requirements. These votes were used to determine the prioritized requirements that are reported in this paper and can be used to direct future developments.
Functional State Modelling of Cultivation Processes: Dissolved Oxygen Limitation State
Directory of Open Access Journals (Sweden)
Olympia Roeva
2015-04-01
Full Text Available A new functional state, namely dissolved oxygen limitation state for both bacteria Escherichia coli and yeast Saccharomyces cerevisiae fed-batch cultivation processes is presented in this study. Functional state modelling approach is applied to cultivation processes in order to overcome the main disadvantages of using global process model, namely complex model structure and a big number of model parameters. Alongwith the newly introduced dissolved oxygen limitation state, second acetate production state and first acetate production state are recognized during the fed-batch cultivation of E. coli, while mixed oxidative state and first ethanol production state are recognized during the fed-batch cultivation of S. cerevisiae. For all mentioned above functional states both structural and parameter identification is here performed based on experimental data of E. coli and S. cerevisiae fed-batch cultivations.
Zayeri, Farid; Mansouri, Anita; Sheidaei, Ali; Rahimzadeh, Shadi; Rezaei, Nazila; Modirian, Mitra; Khademioureh, Sara; Baghestani, Ahmad Reza; Farzadfar, Farshad
2016-01-01
Stomach cancer is the fifth most common cancer and the third leading cause of death among cancers throughout the world. Therefore, stomach cancer outcomes can affect health systems at the national and international levels. Although stomach cancer mortality and incidence rates have decreased in developed countries, these indicators have a raising trend in East Asian developing countries, particularity in Iran. In this study, we aimed to determine the time trend of age-standardized rates of stomach cancer in different districts of Iran from 2000 to 2010. Cases of cancer were registered using a pathology-based system during 2000-2007 and with a population-based system since 2008 in Iran. In this study, we collected information about the incidence of stomach cancer during a 10 year period for 31 provinces and 376 districts, with a total of 49,917 cases. We employed two statistical approaches (a random effects and a random effects Markov model) for modeling the incidence of stomach cancer in different districts of Iran during the studied period. The random effects model showed that the incidence rate of stomach cancer among males and females had an increasing trend and it increased by 2.38 and 0.87 persons every year, respectively. However, after adjusting for previous responses, the random effects Markov model showed an increasing rate of 1.53 and 0.75 for males and females, respectively. This study revealed that there are significant differences between different areas of Iran in terms of age-standardized incidence rates of stomach cancer. Our study suggests that a random effects Markov model can adjust for effects of previous. responses.
Embedded systems development from functional models to implementations
Zeng, Haibo; Natale, Marco; Marwedel, Peter
2014-01-01
This book offers readers broad coverage of techniques to model, verify and validate the behavior and performance of complex distributed embedded systems. The authors attempt to bridge the gap between the three disciplines of model-based design, real-time analysis and model-driven development, for a better understanding of the ways in which new development flows can be constructed, going from system-level modeling to the correct and predictable generation of a distributed implementation, leveraging current and future research results. Describes integration of heterogeneous models; Discusses synthesis of task model implementations and code implementations; Compares model-based design vs. model-driven approaches; Explains how to enforce correctness by construction in the functional and time domains; Includes optimization techniques for control performance.
DEFF Research Database (Denmark)
Soerjomataram, Isabelle; de Vries, Esther; Engholm, Gerda
2010-01-01
Prevent v.3.01 to assess the changes in incidence as a result of risk factor changes. Incidence of lung and breast cancer until 2050 was predicted under two scenarios: ideal (total elimination of smoking and reduction of alcohol intake to maximum 1units/d for women) and optimistic (decreasing prevalence......PURPOSE: Among the known risk factors, smoking is clearly related to the incidence of lung cancer and alcohol consumption is to breast cancer. In this manuscript we modelled the potential benefits of reductions in smoking or alcohol prevalence for the burden of these cancers. METHOD: We used...... of risk factors because of a 10% increase in cigarette and alcohol beverage price, repeated every 5years). Danish data from the household surveys, cancer registration and Eurostat were used. RESULTS: Up to 49% less new lung cancer cases can be expected in 2050 if smoking were to be completely eliminated...
Quark fragmentation functions in NJL-jet model
Bentz, Wolfgang; Matevosyan, Hrayr; Thomas, Anthony
2014-09-01
We report on our studies of quark fragmentation functions in the Nambu-Jona-Lasinio (NJL) - jet model. The results of Monte-Carlo simulations for the fragmentation functions to mesons and nucleons, as well as to pion and kaon pairs (dihadron fragmentation functions) are presented. The important role of intermediate vector meson resonances for those semi-inclusive deep inelastic production processes is emphasized. Our studies are very relevant for the extraction of transverse momentum dependent quark distribution functions from measured scattering cross sections. We report on our studies of quark fragmentation functions in the Nambu-Jona-Lasinio (NJL) - jet model. The results of Monte-Carlo simulations for the fragmentation functions to mesons and nucleons, as well as to pion and kaon pairs (dihadron fragmentation functions) are presented. The important role of intermediate vector meson resonances for those semi-inclusive deep inelastic production processes is emphasized. Our studies are very relevant for the extraction of transverse momentum dependent quark distribution functions from measured scattering cross sections. Supported by Grant in Aid for Scientific Research, Japanese Ministry of Education, Culture, Sports, Science and Technology, Project No. 20168769.
Driver steering model for closed-loop steering function analysis
Bolia, Pratiksh; Weiskircher, Thomas; Müller, Steffen
2014-05-01
In this paper, a two level preview driver steering control model for the use in numerical vehicle dynamics simulation is introduced. The proposed model is composed of cascaded control loops: The outer loop is the path following layer based on potential field framework. The inner loop tries to capture the driver's physical behaviour. The proposed driver model allows easy implementation of different driving situations to simulate a wide range of different driver types, moods and vehicle types. The expediency of the proposed driver model is shown with the help of developed driver steering assist (DSA) function integrated with a conventional series production (Electric Power steering System with rack assist servo unit) system. With the help of the DSA assist function, the driver is prevented from over saturating the front tyre forces and loss of stability and controllability during cornering. The simulation results show different driver reactions caused by the change in the parameters or properties of the proposed driver model if the DSA assist function is activated. Thus, the proposed driver model is useful for the advanced driver steering and vehicle stability assist function evaluation in the early stage of vehicle dynamics handling and stability evaluation.
Towards refactoring the Molecular Function Ontology with a UML profile for function modeling.
Burek, Patryk; Loebe, Frank; Herre, Heinrich
2017-10-04
Gene Ontology (GO) is the largest resource for cataloging gene products. This resource grows steadily and, naturally, this growth raises issues regarding the structure of the ontology. Moreover, modeling and refactoring large ontologies such as GO is generally far from being simple, as a whole as well as when focusing on certain aspects or fragments. It seems that human-friendly graphical modeling languages such as the Unified Modeling Language (UML) could be helpful in connection with these tasks. We investigate the use of UML for making the structural organization of the Molecular Function Ontology (MFO), a sub-ontology of GO, more explicit. More precisely, we present a UML dialect, called the Function Modeling Language (FueL), which is suited for capturing functions in an ontologically founded way. FueL is equipped, among other features, with language elements that arise from studying patterns of subsumption between functions. We show how to use this UML dialect for capturing the structure of molecular functions. Furthermore, we propose and discuss some refactoring options concerning fragments of MFO. FueL enables the systematic, graphical representation of functions and their interrelations, including making information explicit that is currently either implicit in MFO or is mainly captured in textual descriptions. Moreover, the considered subsumption patterns lend themselves to the methodical analysis of refactoring options with respect to MFO. On this basis we argue that the approach can increase the comprehensibility of the structure of MFO for humans and can support communication, for example, during revision and further development.
REVIEW: Zebrafish: A Renewed Model System For Functional Genomics
Wen, Xiao-Yan
2008-01-01
In the post genome era, a major goal in molecular biology is to determine the function of the many thousands of genes present in the vertebrate genome. The zebrafish (Danio rerio) provides an almost ideal genetic model to identify the biological roles of these novel genes, in part because their embryos are transparent and develop rapidly. The zebrafish has many advantages over mouse for genome-wide mutagenesis studies, allowing for easier, cheaper and faster functional characterization of novel genes in the vertebrate genome. Many molecular research tools such as chemical mutagenesis, transgenesis, gene trapping, gene knockdown, TILLING, gene targeting, RNAi and chemical genetic screen are now available in zebrafish. Combining all the forward, reverse, and chemical genetic tools, it is expected that zebrafish will make invaluable contribution to vertebrate functional genomics in functional annotation of the genes, modeling human diseases and drug discoveries.
A functional model for feline P-glycoprotein.
van Beusekom, C D; Lange, R; Schrickx, J A
2016-02-01
P-gp (ABCB1) belongs to the group of export transporters that is expressed in various species at biological barriers. Inhibition of P-gp can lead to changes in pharmacokinetics of drugs (drug-drug interactions), which can lead to toxicity and adverse side effects. This study aimed to establish a functional assay to measure the inhibitory potential of veterinary drugs on feline P-gp by means of fluorescence-associated flow cytometry of feline lymphoma cells. In this model, PSC833 and ivermectin potently inhibited P-gp function; cyclosporine and verapamil moderately inhibited P-gp function, whereas ketoconazole, itraconazole, diazepam, and its metabolites had no effect on P-gp function. This model can be used for testing the inhibitory potency of (new) drugs on feline P-gp. © 2015 John Wiley & Sons Ltd.
Pelagic functional group modeling: Progress, challenges and prospects
Hood, Raleigh R.; Laws, Edward A.; Armstrong, Robert A.; Bates, Nicholas R.; Brown, Christopher W.; Carlson, Craig A.; Chai, Fei; Doney, Scott C.; Falkowski, Paul G.; Feely, Richard A.; Friedrichs, Marjorie A. M.; Landry, Michael R.; Keith Moore, J.; Nelson, David M.; Richardson, Tammi L.; Salihoglu, Baris; Schartau, Markus; Toole, Dierdre A.; Wiggert, Jerry D.
2006-03-01
In this paper, we review the state of the art and major challenges in current efforts to incorporate biogeochemical functional groups into models that can be applied on basin-wide and global scales, with an emphasis on models that might ultimately be used to predict how biogeochemical cycles in the ocean will respond to global warming. We define the term "biogeochemical functional group" to refer to groups of organisms that mediate specific chemical reactions in the ocean. Thus, according to this definition, "functional groups" have no phylogenetic meaning—these are composed of many different species with common biogeochemical functions. Substantial progress has been made in the last decade toward quantifying the rates of these various functions and understanding the factors that control them. For some of these groups, we have developed fairly sophisticated models that incorporate this understanding, e.g. for diazotrophs (e.g. Trichodesmium), silica producers (diatoms) and calcifiers (e.g. coccolithophorids and specifically Emiliania huxleyi). However, current representations of nitrogen fixation and calcification are incomplete, i.e., based primarily upon models of Trichodesmium and E. huxleyi, respectively, and many important functional groups have not yet been considered in open-ocean biogeochemical models. Progress has been made over the last decade in efforts to simulate dimethylsulfide (DMS) production and cycling (i.e., by dinoflagellates and prymnesiophytes) and denitrification, but these efforts are still in their infancy, and many significant problems remain. One obvious gap is that virtually all functional group modeling efforts have focused on autotrophic microbes, while higher trophic levels have been completely ignored. It appears that in some cases (e.g., calcification), incorporating higher trophic levels may be essential not only for representing a particular biogeochemical reaction, but also for modeling export. Another serious problem is our
Bread dough rheology: Computing with a damage function model
Tanner, Roger I.; Qi, Fuzhong; Dai, Shaocong
2015-01-01
We describe an improved damage function model for bread dough rheology. The model has relatively few parameters, all of which can easily be found from simple experiments. Small deformations in the linear region are described by a gel-like power-law memory function. A set of large non-reversing deformations - stress relaxation after a step of shear, steady shearing and elongation beginning from rest, and biaxial stretching, is used to test the model. With the introduction of a revised strain measure which includes a Mooney-Rivlin term, all of these motions can be well described by the damage function described in previous papers. For reversing step strains, larger amplitude oscillatory shearing and recoil reasonable predictions have been found. The numerical methods used are discussed and we give some examples.
Linking density functional and mode coupling models for supercooled liquids
Premkumar, Leishangthem; Bidhoodi, Neeta; Das, Shankar P.
2015-01-01
We compare predictions from two familiar models of the metastable supercooled liquid respectively constructed with thermodynamic and dynamic approach. In the so called density functional theory (DFT) the free energy $F[\\rho]$ of the liquid is a functional of the inhomogeneous density $\\rho({\\bf r})$. The metastable state is identified as a local minimum of $F[\\rho]$. The sharp density profile characterizing $\\rho({\\bf r})$ is identified as a single particle oscillator, whose frequency is obta...
Stability of cylindrical plasma in the Bessel function model
International Nuclear Information System (INIS)
Yamagishi, T.; Gimblett, C.G.
1988-01-01
The stability of free boundary ideal and tearing modes in a cylindrical plasma is studied by examining the discontinuity (Δ') of the helical flux function given by the force free Bessel function model at the singular surface. The m = O and m = 1 free boundary tearing modes become strongly unstable when the singular surface is just inside the plasma boundary for a wide range of longitudinal wave numbers. (author)
Testing the Conditional Mean Function of Autoregressive Conditional Duration Models
DEFF Research Database (Denmark)
Hautsch, Nikolaus
be subject to censoring structures. In an empirical study based on financial transaction data we present an application of the model to estimate conditional asset price change probabilities. Evaluating the forecasting properties of the model, it is shown that the proposed approach is a promising competitor...... function. The dynamic properties of the model as well as an assessment of the estimation quality is investigated in a Monte Carlo study. It is illustrated that the model is a useful approach to estimate conditional failure probabilities based on (persistent) serial dependent duration data which might...
Advances on statistical/thermodynamical models for unpolarized structure functions
Energy Technology Data Exchange (ETDEWEB)
Trevisan, Luis A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Mirez, Carlos [Universidade Federal dos Vales do Jequitinhonha e Mucuri, Campus do Mucuri, 39803-371, Teofilo Otoni, Minas Gerais (Brazil); Tomio, Lauro [Instituto de Fisica Teorica, Universidade Estadual Paulista, R. Dr. Bento Teobaldo Ferraz 271, Bl II Barra Funda, 01140070, Sao Paulo, SP (Brazil)
2013-03-25
During the eights and nineties many statistical/thermodynamical models were proposed to describe the nucleons' structure functions and distribution of the quarks in the hadrons. Most of these models describe the compound quarks and gluons inside the nucleon as a Fermi / Bose gas respectively, confined in a MIT bag with continuous energy levels. Another models considers discrete spectrum. Some interesting features of the nucleons are obtained by these models, like the sea asymmetries {sup -}d/{sup -}u and {sup -}d-{sup -}u.
Conserved Functional Motifs and Homology Modeling to Predict Hidden Moonlighting Functional Sites
Wong, Aloysius Tze
2015-06-09
Moonlighting functional centers within proteins can provide them with hitherto unrecognized functions. Here, we review how hidden moonlighting functional centers, which we define as binding sites that have catalytic activity or regulate protein function in a novel manner, can be identified using targeted bioinformatic searches. Functional motifs used in such searches include amino acid residues that are conserved across species and many of which have been assigned functional roles based on experimental evidence. Molecules that were identified in this manner seeking cyclic mononucleotide cyclases in plants are used as examples. The strength of this computational approach is enhanced when good homology models can be developed to test the functionality of the predicted centers in silico, which, in turn, increases confidence in the ability of the identified candidates to perform the predicted functions. Computational characterization of moonlighting functional centers is not diagnostic for catalysis but serves as a rapid screening method, and highlights testable targets from a potentially large pool of candidates for subsequent in vitro and in vivo experiments required to confirm the functionality of the predicted moonlighting centers.
Conserved functional motifs and homology modelling to predict hidden moonlighting functional sites
Directory of Open Access Journals (Sweden)
Helen R Irving
2015-06-01
Full Text Available Moonlighting functional centers within proteins can provide them with hitherto unrecognized functions. Here we review how hidden moonlighting functional centers which we define as binding sites that have catalytic activity or regulate protein function in a novel manner, can be identified using targeted bioinformatic searches. Functional motifs used in such searches include amino acid residues that are conserved across species and many of which have been assigned functional roles based on experimental evidence. Molecules that were identified in this manner seeking cyclic mononucleotide cyclases in plants are used as examples. The strength of this computational approach is enhanced when good homology models can be developed to test the functionality of the predicted centers in silico which in turn, increases confidence in the ability of the identified candidates to perform the predicted functions. Computational characterization of moonlighting functional centers is not diagnostic for catalysis but serves as a rapid screening method, and highlights testable targets from a potentially large pool of candidates for subsequent in vitro and in vivo experiments required to confirm the functionality of the predicted moonlighting centers.
Lamri, A; Bonnefond, A; Meyre, D; Balkau, B; Roussel, R; Marre, M; Froguel, P; Fumeron, F
2016-10-01
GPR120 (encoded by FFAR4) is a lipid sensor that plays an important role in the control of energy balance. GPR120 is activated by long chain fatty acids (FAs) including omega-3 FAs. In humans, the loss of function p.R270H variant of the gene FFAR4 has been associated with a lower protein activity, an increased risk of obesity and higher fasting plasma glucose levels. The aim of this study was to investigate whether p.R270H interacts with dietary fat intake to modulate the risk of type 2 diabetes (T2D, 198 incident; 368 prevalent cases) and overweight (787 incident and 2891 prevalent cases) in the prospective D.E.S.I.R. study (n = 5,212, 9 years follow-up). The association of p.R270H with dietary fat and total calories was assessed by linear mixed models. The interaction between p.R270H and dietary fat on T2D and overweight was assessed by logistic regression analysis. The p.R270H variant had a minor allele frequency of 1.45% and was not significantly associated with total calories intake, fat intake or the total calories derived from fat (%). However, there was a significant interaction between p.R270H and dietary fat modulating the incidence of T2D (Pinteraction = 0.02) where the H-carriers had a higher risk of T2D than RR homozygotes in the low fat intake category only. The interaction between p.R270H and fat intake modulating the incidence and prevalence of overweight was not significant. The p.R270H variant of GPR120 modulates the risk of T2D in interaction with dietary fat intake in the D.E.S.I.R. Copyright © 2016 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.
Using special functions to model the propagation of airborne diseases
Bolaños, Daniela
2014-06-01
Some special functions of the mathematical physics are using to obtain a mathematical model of the propagation of airborne diseases. In particular we study the propagation of tuberculosis in closed rooms and we model the propagation using the error function and the Bessel function. In the model, infected individual emit pathogens to the environment and this infect others individuals who absorb it. The evolution in time of the concentration of pathogens in the environment is computed in terms of error functions. The evolution in time of the number of susceptible individuals is expressed by a differential equation that contains the error function and it is solved numerically for different parametric simulations. The evolution in time of the number of infected individuals is plotted for each numerical simulation. On the other hand, the spatial distribution of the pathogen around the source of infection is represented by the Bessel function K0. The spatial and temporal distribution of the number of infected individuals is computed and plotted for some numerical simulations. All computations were made using software Computer algebra, specifically Maple. It is expected that the analytical results that we obtained allow the design of treatment rooms and ventilation systems that reduce the risk of spread of tuberculosis.
Optimal hemodynamic response model for functional near-infrared spectroscopy
Directory of Open Access Journals (Sweden)
Muhammad Ahmad Kamran
2015-06-01
Full Text Available Functional near-infrared spectroscopy (fNIRS is an emerging non-invasive brain imaging technique and measures brain activities by means of near-infrared light of 650-950 nm wavelengths. The cortical hemodynamic response (HR differs in attributes at different brain regions and on repetition of trials, even if the experimental paradigm is kept exactly the same. Therefore, an HR model that can estimate such variations in the response is the objective of this research. The canonical hemodynamic response function (cHRF is modeled by using two Gamma functions with six unknown parameters. The HRF model is supposed to be linear combination of HRF, baseline and physiological noises (amplitudes and frequencies of physiological noises are supposed to be unknown. An objective function is developed as a square of the residuals with constraints on twelve free parameters. The formulated problem is solved by using an iterative optimization algorithm to estimate the unknown parameters in the model. Inter-subject variations in HRF and physiological noises have been estimated for better cortical functional maps. The accuracy of the algorithm has been verified using ten real and fifteen simulated data sets. Ten healthy subjects participated in the experiment and their HRF for finger-tapping tasks have been estimated and analyzed. The statistical significance of the estimated activity strength parameters has been verified by employing statistical analysis, i.e., (t-value >tcritical and p-value < 0.05.
Functional dynamic factor models with application to yield curve forecasting
Hays, Spencer
2012-09-01
Accurate forecasting of zero coupon bond yields for a continuum of maturities is paramount to bond portfolio management and derivative security pricing. Yet a universal model for yield curve forecasting has been elusive, and prior attempts often resulted in a trade-off between goodness of fit and consistency with economic theory. To address this, herein we propose a novel formulation which connects the dynamic factor model (DFM) framework with concepts from functional data analysis: a DFM with functional factor loading curves. This results in a model capable of forecasting functional time series. Further, in the yield curve context we show that the model retains economic interpretation. Model estimation is achieved through an expectation- maximization algorithm, where the time series parameters and factor loading curves are simultaneously estimated in a single step. Efficient computing is implemented and a data-driven smoothing parameter is nicely incorporated. We show that our model performs very well on forecasting actual yield data compared with existing approaches, especially in regard to profit-based assessment for an innovative trading exercise. We further illustrate the viability of our model to applications outside of yield forecasting.
DEFINE: A Service-Oriented Dynamically Enabling Function Model
Directory of Open Access Journals (Sweden)
Tan Wei-Yi
2017-01-01
In this paper, we introduce an innovative Dynamically Enable Function In Network Equipment (DEFINE to allow tenant get the network service quickly. First, DEFINE decouples an application into different functional components, and connects these function components in a reconfigurable method. Second, DEFINE provides a programmable interface to the third party, who can develop their own processing modules according to their own needs. To verify the effectiveness of this model, we set up an evaluating network with a FPGA-based OpenFlow switch prototype, and deployed several applications on it. Our results show that DEFINE has excellent flexibility and performance.
Directory of Open Access Journals (Sweden)
Yumin Zhou
2014-03-01
Full Text Available BACKGROUND: Biomass smoke is associated with the risk of chronic obstructive pulmonary disease (COPD, but few studies have elaborated approaches to reduce the risk of COPD from biomass burning. The purpose of this study was to determine whether improved cooking fuels and ventilation have effects on pulmonary function and the incidence of COPD. METHODS AND FINDINGS: A 9-y prospective cohort study was conducted among 996 eligible participants aged at least 40 y from November 1, 2002, through November 30, 2011, in 12 villages in southern China. Interventions were implemented starting in 2002 to improve kitchen ventilation (by providing support and instruction for improving biomass stoves or installing exhaust fans and to promote the use of clean fuels (i.e., biogas instead of biomass for cooking (by providing support and instruction for installing household biogas digesters; questionnaire interviews and spirometry tests were performed in 2005, 2008, and 2011. That the interventions improved air quality was confirmed via measurements of indoor air pollutants (i.e., SO₂, CO, CO₂, NO₂, and particulate matter with an aerodynamic diameter of 10 µm or less in a randomly selected subset of the participants' homes. Annual declines in lung function and COPD incidence were compared between those who took up one, both, or neither of the interventions. Use of clean fuels and improved ventilation were associated with a reduced decline in forced expiratory volume in 1 s (FEV₁: decline in FEV₁ was reduced by 12 ml/y (95% CI, 4 to 20 ml/y and 13 ml/y (95% CI, 4 to 23 ml/y in those who used clean fuels and improved ventilation, respectively, compared to those who took up neither intervention, after adjustment for confounders. The combined improvements of use of clean fuels and improved ventilation had the greatest favorable effects on the decline in FEV₁, with a slowing of 16 ml/y (95% CI, 9 to 23 ml/y. The longer the duration of improved fuel use and
Hypnosis as a model of functional neurologic disorders.
Deeley, Q
2016-01-01
In the 19th century it was recognized that neurologic symptoms could be caused by "morbid ideation" as well as organic lesions. The subsequent observation that hysteric (now called "functional") symptoms could be produced and removed by hypnotic suggestion led Charcot to hypothesize that suggestion mediated the effects of ideas on hysteric symptoms through as yet unknown effects on brain activity. The advent of neuroimaging 100 years later revealed strikingly similar neural correlates in experiments matching functional symptoms with clinical analogs created by suggestion. Integrative models of suggested and functional symptoms regard these alterations in brain function as the endpoint of a broader set of changes in information processing due to suggestion. These accounts consider that suggestions alter experience by mobilizing representations from memory systems, and altering causal attributions, during preconscious processing which alters the content of what is provided to our highly edited subjective version of the world. Hypnosis as a model for functional symptoms draws attention to how radical alterations in experience and behavior can conform to the content of mental representations through effects on cognition and brain function. Experimental study of functional symptoms and their suggested counterparts in hypnosis reveals the distinct and shared processes through which this can occur. © 2016 Elsevier B.V. All rights reserved.
Descriptions and models of safety functions - a prestudy
International Nuclear Information System (INIS)
Harms-Ringdahl, L.
1999-09-01
A study has been made with the focus on different theories and applications concerning 'safety functions' and 'barriers'. In this report, a safety function is defined as a technical or organisational function with the aim to reduce probability and/or consequences associated with a hazard. The study contains a limited review of practice and theories related to safety, with a focus on applications from nuclear and industrial safety. The study is based on a literature review and interviews. A summary has been made of definitions and terminology, which shows a large variation. E.g. 'barrier' can have a precise physical and technical meaning, or it can include human, technical and organisational elements. Only a few theoretical models describing safety functions have been found. One section of the report summarises problems related to safety issues and procedures. They concern errors in procedure design and user compliance. A proposal for describing and structuring safety functions has been made. Dimensions in a description could be degree of abstraction, systems level, the different parts of the function, etc. A model for safety functions has been proposed, which includes the division of a safety function in a number connected 'safety function elements'. One conclusion is that there is a potential for improving theories and tools for safety work and procedures. Safety function could be a useful concept in such a development, and advantages and disadvantages with this is discussed. If further work should be done, it is recommended that this is made as a combination of theoretical analysis and case studies
A hive model determination of multiplicity-free Schur function products and skew Schur functions
Dou, Donna Q. J.; Tang, Robert L.; King, Ronald C.
2009-01-01
The hive model is a combinatorial device that may be used to determine Littlewood-Richardson coefficients and study their properties. It represents an alternative to the use of the Littlewood-Richardson rule. Here properties of hives are used to determine all possible multiplicity-free Schur function products and skew Schur function expansions. This confirms the results of Stembridge, Gutschwager, and Thomas and Yong, and sheds light on the combinatorial origin of the conditions for being mul...
Model Adequacy and the Macroevolution of Angiosperm Functional Traits.
Pennell, Matthew W; FitzJohn, Richard G; Cornwell, William K; Harmon, Luke J
2015-08-01
Making meaningful inferences from phylogenetic comparative data requires a meaningful model of trait evolution. It is thus important to determine whether the model is appropriate for the data and the question being addressed. One way to assess this is to ask whether the model provides a good statistical explanation for the variation in the data. To date, researchers have focused primarily on the explanatory power of a model relative to alternative models. Methods have been developed to assess the adequacy, or absolute explanatory power, of phylogenetic trait models, but these have been restricted to specific models or questions. Here we present a general statistical framework for assessing the adequacy of phylogenetic trait models. We use our approach to evaluate the statistical performance of commonly used trait models on 337 comparative data sets covering three key angiosperm functional traits. In general, the models we tested often provided poor statistical explanations for the evolution of these traits. This was true for many different groups and at many different scales. Whether such statistical inadequacy will qualitatively alter inferences drawn from comparative data sets will depend on the context. Regardless, assessing model adequacy can provide interesting biological insights-how and why a model fails to describe variation in a data set give us clues about what evolutionary processes may have driven trait evolution across time.
Regional differences in prediction models of lung function in Germany
Directory of Open Access Journals (Sweden)
Schäper Christoph
2010-04-01
Full Text Available Abstract Background Little is known about the influencing potential of specific characteristics on lung function in different populations. The aim of this analysis was to determine whether lung function determinants differ between subpopulations within Germany and whether prediction equations developed for one subpopulation are also adequate for another subpopulation. Methods Within three studies (KORA C, SHIP-I, ECRHS-I in different areas of Germany 4059 adults performed lung function tests. The available data consisted of forced expiratory volume in one second, forced vital capacity and peak expiratory flow rate. For each study multivariate regression models were developed to predict lung function and Bland-Altman plots were established to evaluate the agreement between predicted and measured values. Results The final regression equations for FEV1 and FVC showed adjusted r-square values between 0.65 and 0.75, and for PEF they were between 0.46 and 0.61. In all studies gender, age, height and pack-years were significant determinants, each with a similar effect size. Regarding other predictors there were some, although not statistically significant, differences between the studies. Bland-Altman plots indicated that the regression models for each individual study adequately predict medium (i.e. normal but not extremely high or low lung function values in the whole study population. Conclusions Simple models with gender, age and height explain a substantial part of lung function variance whereas further determinants add less than 5% to the total explained r-squared, at least for FEV1 and FVC. Thus, for different adult subpopulations of Germany one simple model for each lung function measures is still sufficient.
Towards aspect-oriented functional--structural plant modelling.
Cieslak, Mikolaj; Seleznyova, Alla N; Prusinkiewicz, Przemyslaw; Hanan, Jim
2011-10-01
Functional-structural plant models (FSPMs) are used to integrate knowledge and test hypotheses of plant behaviour, and to aid in the development of decision support systems. A significant amount of effort is being put into providing a sound methodology for building them. Standard techniques, such as procedural or object-oriented programming, are not suited for clearly separating aspects of plant function that criss-cross between different components of plant structure, which makes it difficult to reuse and share their implementations. The aim of this paper is to present an aspect-oriented programming approach that helps to overcome this difficulty. The L-system-based plant modelling language L+C was used to develop an aspect-oriented approach to plant modelling based on multi-modules. Each element of the plant structure was represented by a sequence of L-system modules (rather than a single module), with each module representing an aspect of the element's function. Separate sets of productions were used for modelling each aspect, with context-sensitive rules facilitated by local lists of modules to consider/ignore. Aspect weaving or communication between aspects was made possible through the use of pseudo-L-systems, where the strict-predecessor of a production rule was specified as a multi-module. The new approach was used to integrate previously modelled aspects of carbon dynamics, apical dominance and biomechanics with a model of a developing kiwifruit shoot. These aspects were specified independently and their implementation was based on source code provided by the original authors without major changes. This new aspect-oriented approach to plant modelling is well suited for studying complex phenomena in plant science, because it can be used to integrate separate models of individual aspects of plant development and function, both previously constructed and new, into clearly organized, comprehensive FSPMs. In a future work, this approach could be further
Lyapunov functions for a dengue disease transmission model
Energy Technology Data Exchange (ETDEWEB)
Tewa, Jean Jules [Department of Mathematics, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde (Cameroon)], E-mail: tewa@univ-metz.fr; Dimi, Jean Luc [Department of Mathematics, Faculty of Science, University Marien Ngouabi, P.O. Box 69, Brazzaville (Congo, The Democratic Republic of the)], E-mail: jldimi@yahoo.fr; Bowong, Samuel [Department of Mathematics and Computer Science, Faculty of Science, University of Douala, P.O. Box 24157, Douala (Cameroon)], E-mail: samuelbowong@yahoo.fr
2009-01-30
In this paper, we study a model for the dynamics of dengue fever when only one type of virus is present. For this model, Lyapunov functions are used to show that when the basic reproduction ratio is less than or equal to one, the disease-free equilibrium is globally asymptotically stable, and when it is greater than one there is an endemic equilibrium which is also globally asymptotically stable.
Lyapunov functions for a dengue disease transmission model
International Nuclear Information System (INIS)
Tewa, Jean Jules; Dimi, Jean Luc; Bowong, Samuel
2009-01-01
In this paper, we study a model for the dynamics of dengue fever when only one type of virus is present. For this model, Lyapunov functions are used to show that when the basic reproduction ratio is less than or equal to one, the disease-free equilibrium is globally asymptotically stable, and when it is greater than one there is an endemic equilibrium which is also globally asymptotically stable.
Directory of Open Access Journals (Sweden)
Solomencevs Artūrs
2016-05-01
Full Text Available The approach called “Topological Functioning Model for Software Engineering” (TFM4SE applies the Topological Functioning Model (TFM for modelling the business system in the context of Model Driven Architecture. TFM is a mathematically formal computation independent model (CIM. TFM4SE is compared to an approach that uses BPMN as a CIM. The comparison focuses on CIM modelling and on transformation to UML Sequence diagram on the platform independent (PIM level. The results show the advantages and drawbacks the formalism of TFM brings into the development.
Functional multiple indicators, multiple causes measurement error models.
Tekwe, Carmen D; Zoh, Roger S; Bazer, Fuller W; Wu, Guoyao; Carroll, Raymond J
2017-05-08
Objective measures of oxygen consumption and carbon dioxide production by mammals are used to predict their energy expenditure. Since energy expenditure is not directly observable, it can be viewed as a latent construct with multiple physical indirect measures such as respiratory quotient, volumetric oxygen consumption, and volumetric carbon dioxide production. Metabolic rate is defined as the rate at which metabolism occurs in the body. Metabolic rate is also not directly observable. However, heat is produced as a result of metabolic processes within the body. Therefore, metabolic rate can be approximated by heat production plus some errors. While energy expenditure and metabolic rates are correlated, they are not equivalent. Energy expenditure results from physical function, while metabolism can occur within the body without the occurrence of physical activities. In this manuscript, we present a novel approach for studying the relationship between metabolic rate and indicators of energy expenditure. We do so by extending our previous work on MIMIC ME models to allow responses that are sparsely observed functional data, defining the sparse functional multiple indicators, multiple cause measurement error (FMIMIC ME) models. The mean curves in our proposed methodology are modeled using basis splines. A novel approach for estimating the variance of the classical measurement error based on functional principal components is presented. The model parameters are estimated using the EM algorithm and a discussion of the model's identifiability is provided. We show that the defined model is not a trivial extension of longitudinal or functional data methods, due to the presence of the latent construct. Results from its application to data collected on Zucker diabetic fatty rats are provided. Simulation results investigating the properties of our approach are also presented. © 2017, The International Biometric Society.
Improved protein model quality assessments by changing the target function.
Uziela, Karolis; Menéndez Hurtado, David; Shu, Nanjiang; Wallner, Björn; Elofsson, Arne
2018-03-09
Protein modeling quality is an important part of protein structure prediction. We have for more than a decade developed a set of methods for this problem. We have used various types of description of the protein and different machine learning methodologies. However, common to all these methods has been the target function used for training. The target function in ProQ describes the local quality of a residue in a protein model. In all versions of ProQ the target function has been the S-score. However, other quality estimation functions also exist, which can be divided into superposition- and contact-based methods. The superposition-based methods, such as S-score, are based on a rigid body superposition of a protein model and the native structure, while the contact-based methods compare the local environment of each residue. Here, we examine the effects of retraining our latest predictor, ProQ3D, using identical inputs but different target functions. We find that the contact-based methods are easier to predict and that predictors trained on these measures provide some advantages when it comes to identifying the best model. One possible reason for this is that contact based methods are better at estimating the quality of multi-domain targets. However, training on the S-score gives the best correlation with the GDT_TS score, which is commonly used in CASP to score the global model quality. To take the advantage of both of these features we provide an updated version of ProQ3D that predicts local and global model quality estimates based on different quality estimates. © 2018 Wiley Periodicals, Inc.
The functional neuroanatomy of bipolar disorder: a consensus model
Strakowski, Stephen M; Adler, Caleb M; Almeida, Jorge; Altshuler, Lori L; Blumberg, Hilary P; Chang, Kiki D; DelBello, Melissa P; Frangou, Sophia; McIntosh, Andrew; Phillips, Mary L; Sussman, Jessika E; Townsend, Jennifer D
2013-01-01
Objectives Functional neuroimaging methods have proliferated in recent years, such that functional magnetic resonance imaging, in particular, is now widely used to study bipolar disorder. However, discrepant findings are common. A workgroup was organized by the Department of Psychiatry, University of Cincinnati (Cincinnati, OH, USA) to develop a consensus functional neuroanatomic model of bipolar I disorder based upon the participants’ work as well as that of others. Methods Representatives from several leading bipolar disorder neuroimaging groups were organized to present an overview of their areas of expertise as well as focused reviews of existing data. The workgroup then developed a consensus model of the functional neuroanatomy of bipolar disorder based upon these data. Results Among the participants, a general consensus emerged that bipolar I disorder arises from abnormalities in the structure and function of key emotional control networks in the human brain. Namely, disruption in early development (e.g., white matter connectivity, prefrontal pruning) within brain networks that modulate emotional behavior leads to decreased connectivity among ventral prefrontal networks and limbic brain regions, especially amygdala. This developmental failure to establish healthy ventral prefrontal–limbic modulation underlies the onset of mania and ultimately, with progressive changes throughout these networks over time and with affective episodes, a bipolar course of illness. Conclusions This model provides a potential substrate to guide future investigations and areas needing additional focus are identified. PMID:22631617
Laguerre-Gauss basis functions in observer models
Burgess, Arthur E.
2003-05-01
Observer models based on linear classifiers with basis functions (channels) are useful for evaluation of detection performance with medical images. They allow spatial domain calculations with a covariance matrix of tractable size. The term "channelized Fisher-Hotelling observer" will be used here. It is also called the "channelized Hotelling observer" model. There are an infinite number of basis function (channel ) sets that could be employed. Examples of channel sets that have been used include: difference of Gaussian (DOG) filters, difference of Mesa (DOM) filters and Laguerre-Gauss (LG) basis functions. Another option, sums of LG functions (LGS), will also be presented here. This set has the advantage of having no DC response. The effect of the number of images used to estimate model observer performance will be described, for both filtered 1/f3 noise and GE digital mammogram backgrounds. Finite sample image sets introduce both bias and variance to the estimate. The results presented here agree with previous work on linear classifiers. The LGS basis set gives a small but statistically significant reduction in bias. However, this may not be of much practical benefit. Finally, the effect of varying the number of basis functions included in the set will be addressed. It was found that four LG bases or three LGS bases are adequate.
A review of function modeling : Approaches and applications
Erden, M.S.; Komoto, H.; Van Beek, T.J.; D'Amelio, V.; Echavarria, E.; Tomiyama, T.
2008-01-01
This work is aimed at establishing a common frame and understanding of function modeling (FM) for our ongoing research activities. A comparative review of the literature is performed to grasp the various FM approaches with their commonalities and differences. The relations of FM with the research
Mass corrections to Green functions in instanton vacuum model
International Nuclear Information System (INIS)
Esaibegyan, S.V.; Tamaryan, S.N.
1987-01-01
The first nonvanishing mass corrections to the effective Green functions are calculated in the model of instanton-based vacuum consisting of a superposition of instanton-antiinstanton fluctuations. The meson current correlators are calculated with account of these corrections; the mass spectrum of pseudoscalar octet as well as the value of the kaon axial constant are found. 7 refs
Gene Discovery and Functional Analyses in the Model Plant Arabidopsis
DEFF Research Database (Denmark)
Feng, Cai-ping; Mundy, J.
2006-01-01
The present mini-review describes newer methods and strategies, including transposon and T-DNA insertions, TILLING, Deleteagene, and RNA interference, to functionally analyze genes of interest in the model plant Arabidopsis. The relative advantages and disadvantages of the systems are also...
Partition function of nearest neighbour Ising models: Some new ...
Indian Academy of Sciences (India)
Administrator
insights. †. G NANDHINI and M V SANGARANARAYANAN*. Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036 e-mail: sangara@iitm.ac.in. Abstract. The partition function for one-dimensional nearest neighbour Ising models is estimated by summing all the energy terms in the Hamiltonian for ...
From dynamics to structure and function of model biomolecular systems
Fontaine-Vive-Curtaz, F.
2007-01-01
The purpose of this thesis was to extend recent works on structure and dynamics of hydrogen bonded crystals to model biomolecular systems and biological processes. The tools that we have used are neutron scattering (NS) and density functional theory (DFT) and force field (FF) based simulation
All genus correlation functions for the hermitian 1-matrix model
Eynard, B.
2004-01-01
We rewrite the loop equations of the hermitian matrix model, in a way which allows to compute all the correlation functions, to all orders in the topological $1/N^2$ expansion, as residues on an hyperelliptical curve. Those residues, can be represented diagrammaticaly as Feynmann graphs of a cubic interaction field theory on the curve.
Software Design Modelling with Functional Petri Nets | Bakpo ...
African Journals Online (AJOL)
In this paper, an equivalent functional Petri Net (FPN) model is developed for each of the three constructs of structured programs and a FPN Software prototype proposed for the conventional programming construct: if-then-else statement. The motivating idea is essentially to show that FPNs could be used as an alternative ...
An adaptive complex network model for brain functional networks.
Directory of Open Access Journals (Sweden)
Ignacio J Gomez Portillo
Full Text Available Brain functional networks are graph representations of activity in the brain, where the vertices represent anatomical regions and the edges their functional connectivity. These networks present a robust small world topological structure, characterized by highly integrated modules connected sparsely by long range links. Recent studies showed that other topological properties such as the degree distribution and the presence (or absence of a hierarchical structure are not robust, and show different intriguing behaviors. In order to understand the basic ingredients necessary for the emergence of these complex network structures we present an adaptive complex network model for human brain functional networks. The microscopic units of the model are dynamical nodes that represent active regions of the brain, whose interaction gives rise to complex network structures. The links between the nodes are chosen following an adaptive algorithm that establishes connections between dynamical elements with similar internal states. We show that the model is able to describe topological characteristics of human brain networks obtained from functional magnetic resonance imaging studies. In particular, when the dynamical rules of the model allow for integrated processing over the entire network scale-free non-hierarchical networks with well defined communities emerge. On the other hand, when the dynamical rules restrict the information to a local neighborhood, communities cluster together into larger ones, giving rise to a hierarchical structure, with a truncated power law degree distribution.
Colombian ocean waves and coasts modeled by special functions
Duque Tisnés, Simón
2013-06-01
Modeling the ocean bottom and surface of both Atlantic and Pacific Oceans near the Colombian coast is a subject of increasing attention due to the possibility of finding oil deposits that haven't been discovered, and as a way of monitoring the ocean limits of Colombia with other countries not only covering the possibility of naval intrusion but as a chance to detect submarine devices that are used by illegal groups for different unwished purposes. In the development of this topic it would be necessary to use Standard Hydrodynamic Equations to model the mathematical shape of ocean waves that will take differential equations forms. Those differential equations will be solved using computer algebra software and methods. The mentioned solutions will involve the use of Special Functions such as Bessel Functions, Whittaker, Heun, and so on. Using the Special Functions mentioned above, the obtained results will be simulated by numerical methods obtaining the typical patterns around the Colombian coasts (both surface and bottom). Using this simulation as a non-perturbed state, any change in the patter could be taken as an external perturbation caused by a strange body or device in an specific area or region modeled, building this simulation as an ocean radar or an unusual object finder. It's worth mentioning that the use of stronger or more rigorous methods and more advanced Special Functions would generate better theoretical results, building a more accurate simulation model that would lead to a finest detection.
Systemic Modeling of Biological Functions in Consideration of Physiome Project
Minamitani, Haruyuki
Emerging of the physiome project provides various influences on the medical, biological and pharmaceutical development. In this paper, as an example of physiome research, neural network model analysis providing the conduction mechanisms of pain and tactile sensations was presented, and the functional relations between neural activities of the network cells and stimulus intensity applied on the peripheral receptive fields were described. The modeling presented here is based on the various assumptions made by the results of physiological and anatomical studies reported in the literature. The functional activities of spinothalamic and thalamocortical cells show a good agreement with the physiological and psychophysical functions of somatosensory system that are very instructive for covering the gap between physiologically and psychophysically aspects of pain and tactile sensation.
Functional Model to Estimate the Inelastic Displacement Ratio
Directory of Open Access Journals (Sweden)
Ceangu Vlad
2017-12-01
Full Text Available In this paper a functional model to estimate the inelastic displacement ratio as a function of the ductility factor is presented. The coefficients of the functional model are approximated using nonlinear regression. The used data is in the form of computed displacement for an inelastic single degree of freedom system with a fixed ductility factor. The inelastic seismic response spectra of constant ductility factors are used for generating data. A method for selecting ground-motions that have similar frequency content to that of the ones picked for the comparison is presented. The variability of the seismic response of nonlinear single degree of freedom systems with different hysteretic behavior is presented.
Functional Nonlinear Mixed Effects Models For Longitudinal Image Data
Luo, Xinchao; Zhu, Lixing; Kong, Linglong; Zhu, Hongtu
2015-01-01
Motivated by studying large-scale longitudinal image data, we propose a novel functional nonlinear mixed effects modeling (FN-MEM) framework to model the nonlinear spatial-temporal growth patterns of brain structure and function and their association with covariates of interest (e.g., time or diagnostic status). Our FNMEM explicitly quantifies a random nonlinear association map of individual trajectories. We develop an efficient estimation method to estimate the nonlinear growth function and the covariance operator of the spatial-temporal process. We propose a global test and a simultaneous confidence band for some specific growth patterns. We conduct Monte Carlo simulation to examine the finite-sample performance of the proposed procedures. We apply FNMEM to investigate the spatial-temporal dynamics of white-matter fiber skeletons in a national database for autism research. Our FNMEM may provide a valuable tool for charting the developmental trajectories of various neuropsychiatric and neurodegenerative disorders. PMID:26213453
Development on electromagnetic impedance function modeling and its estimation
International Nuclear Information System (INIS)
Sutarno, D.
2015-01-01
Today the Electromagnetic methods such as magnetotellurics (MT) and controlled sources audio MT (CSAMT) is used in a broad variety of applications. Its usefulness in poor seismic areas and its negligible environmental impact are integral parts of effective exploration at minimum cost. As exploration was forced into more difficult areas, the importance of MT and CSAMT, in conjunction with other techniques, has tended to grow continuously. However, there are obviously important and difficult problems remaining to be solved concerning our ability to collect process and interpret MT as well as CSAMT in complex 3D structural environments. This talk aim at reviewing and discussing the recent development on MT as well as CSAMT impedance functions modeling, and also some improvements on estimation procedures for the corresponding impedance functions. In MT impedance modeling, research efforts focus on developing numerical method for computing the impedance functions of three dimensionally (3-D) earth resistivity models. On that reason, 3-D finite elements numerical modeling for the impedances is developed based on edge element method. Whereas, in the CSAMT case, the efforts were focused to accomplish the non-plane wave problem in the corresponding impedance functions. Concerning estimation of MT and CSAMT impedance functions, researches were focused on improving quality of the estimates. On that objective, non-linear regression approach based on the robust M-estimators and the Hilbert transform operating on the causal transfer functions, were used to dealing with outliers (abnormal data) which are frequently superimposed on a normal ambient MT as well as CSAMT noise fields. As validated, the proposed MT impedance modeling method gives acceptable results for standard three dimensional resistivity models. Whilst, the full solution based modeling that accommodate the non-plane wave effect for CSAMT impedances is applied for all measurement zones, including near-, transition
Development on electromagnetic impedance function modeling and its estimation
Energy Technology Data Exchange (ETDEWEB)
Sutarno, D., E-mail: Sutarno@fi.itb.ac.id [Earth Physics and Complex System Division Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung (Indonesia)
2015-09-30
Today the Electromagnetic methods such as magnetotellurics (MT) and controlled sources audio MT (CSAMT) is used in a broad variety of applications. Its usefulness in poor seismic areas and its negligible environmental impact are integral parts of effective exploration at minimum cost. As exploration was forced into more difficult areas, the importance of MT and CSAMT, in conjunction with other techniques, has tended to grow continuously. However, there are obviously important and difficult problems remaining to be solved concerning our ability to collect process and interpret MT as well as CSAMT in complex 3D structural environments. This talk aim at reviewing and discussing the recent development on MT as well as CSAMT impedance functions modeling, and also some improvements on estimation procedures for the corresponding impedance functions. In MT impedance modeling, research efforts focus on developing numerical method for computing the impedance functions of three dimensionally (3-D) earth resistivity models. On that reason, 3-D finite elements numerical modeling for the impedances is developed based on edge element method. Whereas, in the CSAMT case, the efforts were focused to accomplish the non-plane wave problem in the corresponding impedance functions. Concerning estimation of MT and CSAMT impedance functions, researches were focused on improving quality of the estimates. On that objective, non-linear regression approach based on the robust M-estimators and the Hilbert transform operating on the causal transfer functions, were used to dealing with outliers (abnormal data) which are frequently superimposed on a normal ambient MT as well as CSAMT noise fields. As validated, the proposed MT impedance modeling method gives acceptable results for standard three dimensional resistivity models. Whilst, the full solution based modeling that accommodate the non-plane wave effect for CSAMT impedances is applied for all measurement zones, including near-, transition
Optimal hemodynamic response model for functional near-infrared spectroscopy.
Kamran, Muhammad A; Jeong, Myung Yung; Mannan, Malik M N
2015-01-01
Functional near-infrared spectroscopy (fNIRS) is an emerging non-invasive brain imaging technique and measures brain activities by means of near-infrared light of 650-950 nm wavelengths. The cortical hemodynamic response (HR) differs in attributes at different brain regions and on repetition of trials, even if the experimental paradigm is kept exactly the same. Therefore, an HR model that can estimate such variations in the response is the objective of this research. The canonical hemodynamic response function (cHRF) is modeled by two Gamma functions with six unknown parameters (four of them to model the shape and other two to scale and baseline respectively). The HRF model is supposed to be a linear combination of HRF, baseline, and physiological noises (amplitudes and frequencies of physiological noises are supposed to be unknown). An objective function is developed as a square of the residuals with constraints on 12 free parameters. The formulated problem is solved by using an iterative optimization algorithm to estimate the unknown parameters in the model. Inter-subject variations in HRF and physiological noises have been estimated for better cortical functional maps. The accuracy of the algorithm has been verified using 10 real and 15 simulated data sets. Ten healthy subjects participated in the experiment and their HRF for finger-tapping tasks have been estimated and analyzed. The statistical significance of the estimated activity strength parameters has been verified by employing statistical analysis (i.e., t-value > t critical and p-value < 0.05).
Modeling of EUV photoresists with a resist point spread function
International Nuclear Information System (INIS)
Cain, Jason P.; Naulleau, Patrick; Spanos, Costas J.
2005-01-01
Extreme ultraviolet (EUV) lithography is under development for possible deployment at the 32-nm technology node. One active area of research in this field is the development of photoresists that can meet the stringent requirements (high resolution, high sensitivity, low LER, etc.) of lithography in this regime. In order to facilitate research in this and other areas related to EUV lithography, a printing station based upon the 0.3-NA Micro Exposure Tool (MET) optic was established at the Advanced Light Source, a synchrotron facility at Lawrence Berkeley National Laboratory. A resist modeling technique using a resist point spread function has been shown to have good agreement with experiments for certain EUV resists such as Shipley EUV-2D [2]. The resist point spread function is a two-dimensional function that, when convolved with the simulated aerial image for a given mask pattern and applied to a threshold function, gives a representation of the photoresist pattern remaining after development. The simplicity of this modeling approach makes it attractive for rapid modeling of photoresists for process development applications. In this work, the resist point spread functions for three current high-resolution EUV photoresists [Rohm and Haas EUV-2D, Rohm and Haas MET-1K (XP 3454C), and KRS] are extracted experimentally. This model is then used in combination with aerial image simulations (including effects of projection optic aberrations) to predict the resist pattern for a variety of test patterns. A comparison is made between these predictions and experimental results to evaluate the effectiveness of this modeling technique for newer high-resolution EUV resists
Bessel functions in mass action modeling of memories and remembrances
Energy Technology Data Exchange (ETDEWEB)
Freeman, Walter J. [Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3206 (United States); Capolupo, Antonio [Dipartimento di Fisica, E.R. Caianiello Universitá di Salerno, and INFN Gruppo collegato di Salerno, Fisciano 84084 (Italy); Kozma, Robert [Department of Mathematics, Memphis University, Memphis, TN 38152 (United States); Olivares del Campo, Andrés [The Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BZ (United Kingdom); Vitiello, Giuseppe, E-mail: vitiello@sa.infn.it [Dipartimento di Fisica, E.R. Caianiello Universitá di Salerno, and INFN Gruppo collegato di Salerno, Fisciano 84084 (Italy)
2015-10-02
Data from experimental observations of a class of neurological processes (Freeman K-sets) present functional distribution reproducing Bessel function behavior. We model such processes with couples of damped/amplified oscillators which provide time dependent representation of Bessel equation. The root loci of poles and zeros conform to solutions of K-sets. Some light is shed on the problem of filling the gap between the cellular level dynamics and the brain functional activity. Breakdown of time-reversal symmetry is related with the cortex thermodynamic features. This provides a possible mechanism to deduce lifetime of recorded memory. - Highlights: • We consider data from observations of impulse responses of cortex to electric shocks. • These data are fitted by Bessel functions which may be represented by couples of damped/amplified oscillators. • We study the data by using couples of damped/amplified oscillators. • We discuss lifetime and other properties of the considered brain processes.
Universality of correlation functions in random matrix models of QCD
International Nuclear Information System (INIS)
Jackson, A.D.; Sener, M.K.; Verbaarschot, J.J.M.
1997-01-01
We demonstrate the universality of the spectral correlation functions of a QCD inspired random matrix model that consists of a random part having the chiral structure of the QCD Dirac operator and a deterministic part which describes a schematic temperature dependence. We calculate the correlation functions analytically using the technique of Itzykson-Zuber integrals for arbitrary complex supermatrices. An alternative exact calculation for arbitrary matrix size is given for the special case of zero temperature, and we reproduce the well-known Laguerre kernel. At finite temperature, the microscopic limit of the correlation functions are calculated in the saddle-point approximation. The main result of this paper is that the microscopic universality of correlation functions is maintained even though unitary invariance is broken by the addition of a deterministic matrix to the ensemble. (orig.)
Production functions for climate policy modeling. An empirical analysis
International Nuclear Information System (INIS)
Van der Werf, Edwin
2008-01-01
Quantitative models for climate policy modeling differ in the production structure used and in the sizes of the elasticities of substitution. The empirical foundation for both is generally lacking. This paper estimates the parameters of 2-level CES production functions with capital, labour and energy as inputs, and is the first to systematically compare all nesting structures. Using industry-level data from 12 OECD countries, we find that the nesting structure where capital and labour are combined first, fits the data best, but for most countries and industries we cannot reject that all three inputs can be put into one single nest. These two nesting structures are used by most climate models. However, while several climate policy models use a Cobb-Douglas function for (part of the) production function, we reject elasticities equal to one, in favour of considerably smaller values. Finally we find evidence for factor-specific technological change. With lower elasticities and with factor-specific technological change, some climate policy models may find a bigger effect of endogenous technological change on mitigating the costs of climate policy. (author)
Identifying Model-Based Reconfiguration Goals through Functional Deficiencies
Benazera, Emmanuel; Trave-Massuyes, Louise
2004-01-01
Model-based diagnosis is now advanced to the point autonomous systems face some uncertain and faulty situations with success. The next step toward more autonomy is to have the system recovering itself after faults occur, a process known as model-based reconfiguration. After faults occur, given a prediction of the nominal behavior of the system and the result of the diagnosis operation, this paper details how to automatically determine the functional deficiencies of the system. These deficiencies are characterized in the case of uncertain state estimates. A methodology is then presented to determine the reconfiguration goals based on the deficiencies. Finally, a recovery process interleaves planning and model predictive control to restore the functionalities in prioritized order.
Parton distribution functions with QED corrections in the valon model
Mottaghizadeh, Marzieh; Taghavi Shahri, Fatemeh; Eslami, Parvin
2017-10-01
The parton distribution functions (PDFs) with QED corrections are obtained by solving the QCD ⊗QED DGLAP evolution equations in the framework of the "valon" model at the next-to-leading-order QCD and the leading-order QED approximations. Our results for the PDFs with QED corrections in this phenomenological model are in good agreement with the newly related CT14QED global fits code [Phys. Rev. D 93, 114015 (2016), 10.1103/PhysRevD.93.114015] and APFEL (NNPDF2.3QED) program [Comput. Phys. Commun. 185, 1647 (2014), 10.1016/j.cpc.2014.03.007] in a wide range of x =[10-5,1 ] and Q2=[0.283 ,108] GeV2 . The model calculations agree rather well with those codes. In the latter, we proposed a new method for studying the symmetry breaking of the sea quark distribution functions inside the proton.
Predicting Cumulative Incidence Probability by Direct Binomial Regression
DEFF Research Database (Denmark)
Scheike, Thomas H.; Zhang, Mei-Jie
Binomial modelling; cumulative incidence probability; cause-specific hazards; subdistribution hazard......Binomial modelling; cumulative incidence probability; cause-specific hazards; subdistribution hazard...
A propositional representation model of anatomical and functional brain data.
Maturana, Pablo; Batrancourt, Bénédicte
2011-01-01
Networks can represent a large number of systems. Recent advances in the domain of networks have been transferred to the field of neuroscience. For example, the graph model has been used in neuroscience research as a methodological tool to examine brain networks organization, topology and complex dynamics, as well as a framework to test the structure-function hypothesis using neuroimaging data. In the current work we propose a graph-theoretical framework to represent anatomical, functional and neuropsychological assessment instruments information. On the one hand, interrelationships between anatomic elements constitute an anatomical graph. On the other hand, a functional graph contains several cognitive functions and their more elementary cognitive processes. Finally, the neuropsychological assessment instruments graph includes several neuropsychological tests and scales linked with their different sub-tests and variables. The two last graphs are connected by relations of type "explore" linking a particular instrument with the cognitive function it explores. We applied this framework to a sample of patients with focal brain damage. Each patient was related to: (i) the cerebral entities injured (assessed with structural neuroimaging data) and (ii) the neusopsychological assessment tests carried out (weight by performance). Our model offers a suitable platform to visualize patients' relevant information, facilitating the representation, standardization and sharing of clinical data. At the same time, the integration of a large number of patients in this framework will make possible to explore relations between anatomy (injured entities) and function (performance in different tests assessing different cognitive functions) and the use of neurocomputational tools for graph analysis may help diagnostic and contribute to the comprehension of neural bases of cognitive functions. Copyright © 2011 Elsevier Ltd. All rights reserved.
Future of Plant Functional Types in Terrestrial Biosphere Models
Wullschleger, S. D.; Euskirchen, E. S.; Iversen, C. M.; Rogers, A.; Serbin, S.
2015-12-01
Earth system models describe the physical, chemical, and biological processes that govern our global climate. While it is difficult to single out one component as being more important than another in these sophisticated models, terrestrial vegetation is a critical player in the biogeochemical and biophysical dynamics of the Earth system. There is much debate, however, as to how plant diversity and function should be represented in these models. Plant functional types (PFTs) have been adopted by modelers to represent broad groupings of plant species that share similar characteristics (e.g. growth form) and roles (e.g. photosynthetic pathway) in ecosystem function. In this review the PFT concept is traced from its origin in the early 1800s to its current use in regional and global dynamic vegetation models (DVMs). Special attention is given to the representation and parameterization of PFTs and to validation and benchmarking of predicted patterns of vegetation distribution in high-latitude ecosystems. These ecosystems are sensitive to changing climate and thus provide a useful test case for model-based simulations of past, current, and future distribution of vegetation. Models that incorporate the PFT concept predict many of the emerging patterns of vegetation change in tundra and boreal forests, given known processes of tree mortality, treeline migration, and shrub expansion. However, representation of above- and especially belowground traits for specific PFTs continues to be problematic. Potential solutions include developing trait databases and replacing fixed parameters for PFTs with formulations based on trait co-variance and empirical trait-environment relationships. Surprisingly, despite being important to land-atmosphere interactions of carbon, water, and energy, PFTs such as moss and lichen are largely absent from DVMs. Close collaboration among those involved in modelling with the disciplines of taxonomy, biogeography, ecology, and remote sensing will be
Development of an Upper Extremity Function Measurement Model.
Hong, Ickpyo; Simpson, Annie N; Li, Chih-Ying; Velozo, Craig A
This study demonstrated the development of a measurement model for gross upper-extremity function (GUE). The dependent variable was the Rasch calibration of the 27 ICF-GUE test items. The predictors were object weight, lifting distance from floor, carrying, and lifting. Multiple regression was used to investigate the contribution that each independent variable makes to the model with 203 outpatients. Object weight and lifting distance were the only statistically and clinically significant independent variables in the model, accounting for 83% of the variance (p model indicates that, with each one pound increase in object weight, item challenge increases by 0.16 (p measurement model for the ICF-GUE can be explained by object weight and distance lifted from the floor.
A Comparison of Functional Models for Use in the Function-Failure Design Method
Stock, Michael E.; Stone, Robert B.; Tumer, Irem Y.
2006-01-01
When failure analysis and prevention, guided by historical design knowledge, are coupled with product design at its conception, shorter design cycles are possible. By decreasing the design time of a product in this manner, design costs are reduced and the product will better suit the customer s needs. Prior work indicates that similar failure modes occur with products (or components) with similar functionality. To capitalize on this finding, a knowledge base of historical failure information linked to functionality is assembled for use by designers. One possible use for this knowledge base is within the Elemental Function-Failure Design Method (EFDM). This design methodology and failure analysis tool begins at conceptual design and keeps the designer cognizant of failures that are likely to occur based on the product s functionality. The EFDM offers potential improvement over current failure analysis methods, such as FMEA, FMECA, and Fault Tree Analysis, because it can be implemented hand in hand with other conceptual design steps and carried throughout a product s design cycle. These other failure analysis methods can only truly be effective after a physical design has been completed. The EFDM however is only as good as the knowledge base that it draws from, and therefore it is of utmost importance to develop a knowledge base that will be suitable for use across a wide spectrum of products. One fundamental question that arises in using the EFDM is: At what level of detail should functional descriptions of components be encoded? This paper explores two approaches to populating a knowledge base with actual failure occurrence information from Bell 206 helicopters. Functional models expressed at various levels of detail are investigated to determine the necessary detail for an applicable knowledge base that can be used by designers in both new designs as well as redesigns. High level and more detailed functional descriptions are derived for each failed component based
Function modeling improves the efficiency of spatial modeling using big data from remote sensing
John Hogland; Nathaniel Anderson
2017-01-01
Spatial modeling is an integral component of most geographic information systems (GISs). However, conventional GIS modeling techniques can require substantial processing time and storage space and have limited statistical and machine learning functionality. To address these limitations, many have parallelized spatial models using multiple coding libraries and have...
Extreme compression and modeling of bidirectional texture function.
Haindl, Michal; Filip, Jirí
2007-10-01
The recent advanced representation for realistic real-world materials in virtual reality applications is the Bidirectional Texture Function (BTF) which describes rough texture appearance for varying illumination and viewing conditions. Such a function can be represented by thousands of measurements (images) per material sample. The resulting BTF size excludes its direct rendering in graphical applications and some compression of these huge BTF data spaces is obviously inevitable. In this paper we present a novel, fast probabilistic model-based algorithm for realistic BTF modeling allowing an extreme compression with the possibility of a fast hardware implementation. Its ultimate aim is to create a visual impression of the same material without a pixel-wise correspondence to the original measurements. The analytical step of the algorithm starts with a BTF space segmentation and a range map estimation by photometric stereo of the BTF surface, followed by the spectral and spatial factorization of selected sub-space color texture images. Single mono-spectral band-limited factors are independently modeled by their dedicated spatial probabilistic model. During rendering, the sub-space images of arbitrary size are synthesized and both color (possibly multi-spectral) and range information is combined in a bump-mapping filter according to the view and illumination directions. The presented model offers a huge BTF compression ratio unattainable by any alternative sampling-based BTF synthesis method. Simultaneously this model can be used to reconstruct missing parts of the BTF measurement space.
Thresholding functional connectomes by means of mixture modeling.
Bielczyk, Natalia Z; Walocha, Fabian; Ebel, Patrick W; Haak, Koen V; Llera, Alberto; Buitelaar, Jan K; Glennon, Jeffrey C; Beckmann, Christian F
2018-05-01
Functional connectivity has been shown to be a very promising tool for studying the large-scale functional architecture of the human brain. In network research in fMRI, functional connectivity is considered as a set of pair-wise interactions between the nodes of the network. These interactions are typically operationalized through the full or partial correlation between all pairs of regional time series. Estimating the structure of the latent underlying functional connectome from the set of pair-wise partial correlations remains an open research problem though. Typically, this thresholding problem is approached by proportional thresholding, or by means of parametric or non-parametric permutation testing across a cohort of subjects at each possible connection. As an alternative, we propose a data-driven thresholding approach for network matrices on the basis of mixture modeling. This approach allows for creating subject-specific sparse connectomes by modeling the full set of partial correlations as a mixture of low correlation values associated with weak or unreliable edges in the connectome and a sparse set of reliable connections. Consequently, we propose to use alternative thresholding strategy based on the model fit using pseudo-False Discovery Rates derived on the basis of the empirical null estimated as part of the mixture distribution. We evaluate the method on synthetic benchmark fMRI datasets where the underlying network structure is known, and demonstrate that it gives improved performance with respect to the alternative methods for thresholding connectomes, given the canonical thresholding levels. We also demonstrate that mixture modeling gives highly reproducible results when applied to the functional connectomes of the visual system derived from the n-back Working Memory task in the Human Connectome Project. The sparse connectomes obtained from mixture modeling are further discussed in the light of the previous knowledge of the functional architecture
Spin-density functional for exchange anisotropic Heisenberg model
International Nuclear Information System (INIS)
Prata, G.N.; Penteado, P.H.; Souza, F.C.; Libero, Valter L.
2009-01-01
Ground-state energies for antiferromagnetic Heisenberg models with exchange anisotropy are estimated by means of a local-spin approximation made in the context of the density functional theory. Correlation energy is obtained using the non-linear spin-wave theory for homogeneous systems from which the spin functional is built. Although applicable to chains of any size, the results are shown for small number of sites, to exhibit finite-size effects and allow comparison with exact-numerical data from direct diagonalization of small chains.
Using the Drosophila Nephrocyte to Model Podocyte Function and Disease
Directory of Open Access Journals (Sweden)
Martin Helmstädter
2017-12-01
Full Text Available Glomerular disorders are a major cause of end-stage renal disease and effective therapies are often lacking. Nephrocytes are considered to be part of the Drosophila excretory system and form slit diaphragms across cellular membrane invaginations. Nehphrocytes have been shown to share functional, morphological, and molecular features with podocytes, which form the glomerular filter in vertebrates. Here, we report the progress and the evolving tool-set of this model system. Combining a functional, accessible slit diaphragm with the power of the genetic tool-kit in Drosophila, the nephrocyte has the potential to greatly advance our understanding of the glomerular filtration barrier in health and disease.
Analysis of a Heroin Epidemic Model with Saturated Treatment Function
Directory of Open Access Journals (Sweden)
Isaac Mwangi Wangari
2017-01-01
Full Text Available A mathematical model is developed that examines how heroin addiction spreads in society. The model is formulated to take into account the treatment of heroin users by incorporating a realistic functional form that “saturates” representing the limited availability of treatment. Bifurcation analysis reveals that the model has an intrinsic backward bifurcation whenever the saturation parameter is larger than a fixed threshold. We are particularly interested in studying the model’s global stability. In the absence of backward bifurcations, Lyapunov functions can often be found and used to prove global stability. However, in the presence of backward bifurcations, such Lyapunov functions may not exist or may be difficult to construct. We make use of the geometric approach to global stability to derive a condition that ensures that the system is globally asymptotically stable. Numerical simulations are also presented to give a more complete representation of the model dynamics. Sensitivity analysis performed by Latin hypercube sampling (LHS suggests that the effective contact rate in the population, the relapse rate of heroin users undergoing treatment, and the extent of saturation of heroin users are mechanisms fuelling heroin epidemic proliferation.
CSIR Research Space (South Africa)
Mbecke, P
2010-06-01
Full Text Available abuse ignore or underplay integration of multiple variables from different aspects contributing to the incidence of child abuse. Newberger et al (1983) demonstrated the need for further research and the importance of theory for knowledge, prevention... structures in South Africa as resulted from measures put in place by the past apartheid Government. Apartheid forced parents to travel great distances to get to work or to work away from home (migrant labor policies). The ?Group Areas Act? stipulated...
Auditory temporal integration and the power function model.
Gerken, G M; Bhat, V K; Hutchison-Clutter, M
1990-08-01
The auditory temporal integration function was studied with the objective of improving both its quantitative description and the specification of its principle independent variable, stimulus duration. In Sec. I, temporal integration data from 20 studies were subjected to uniform analyses using standardized definitions of duration and two models of temporal integration. Analyses revealed that these data were best described by a power function model used in conjunction with a definition of duration, termed assigned duration, that de-emphasized the rise/fall portions of the stimuli. There was a strong effect of stimulus frequency and, in general, the slope of the temporal integration function was less than 10 dB per decade of duration; i.e., a power function exponent less than 1.0. In Sec. II, an experimental study was performed to further evaluate the models and definitions. Detection thresholds were measured in 11 normal-hearing human subjects using a total of 24 single-burst and multiple-burst acoustic stimuli of 3.125 kHz. The issues addressed are: the quantitative description of the temporal integration function; the definition of stimulus duration; the similarity of the integration processes for single-burst and multiple-burst stimuli; and the contribution of rise/fall time to the integration process. A power function in conjunction with the assigned duration definition was again most effective in describing the data. Single- and multiple-burst stimuli both seemed to be integrated by the same central mechanism, with data for each type of stimulus being described by a power function exponent of approximately 0.6 at 3.125 kHz. It was concluded that the contribution of the rise/fall portions of the stimuli can be factored out from the rest of the temporal integration process. In Sec. III, the conclusions that emerged from the review of published work and the present experimental work suggested that auditory temporal integration is best described by a power function
Directory of Open Access Journals (Sweden)
Juan Carlos Rosales
2014-01-01
Full Text Available American tegumentary leishmaniasis (ATL is a disease transmitted to humans by the female sandflies of the genus Lutzomyia. Several factors are involved in the disease transmission cycle. In this work only rainfall and deforestation were considered to assess the variability in the incidence of ATL. In order to reach this goal, monthly recorded data of the incidence of ATL in Orán, Salta, Argentina, were used, in the period 1985–2007. The square root of the relative incidence of ATL and the corresponding variance were formulated as time series, and these data were smoothed by moving averages of 12 and 24 months, respectively. The same procedure was applied to the rainfall data. Typical months, which are April, August, and December, were found and allowed us to describe the dynamical behavior of ATL outbreaks. These results were tested at 95% confidence level. We concluded that the variability of rainfall would not be enough to justify the epidemic outbreaks of ATL in the period 1997–2000, but it consistently explains the situation observed in the years 2002 and 2004. Deforestation activities occurred in this region could explain epidemic peaks observed in both years and also during the entire time of observation except in 2005–2007.
Photonic encryption : modeling and functional analysis of all optical logic.
Energy Technology Data Exchange (ETDEWEB)
Tang, Jason D.; Schroeppel, Richard Crabtree; Robertson, Perry J.
2004-10-01
With the build-out of large transport networks utilizing optical technologies, more and more capacity is being made available. Innovations in Dense Wave Division Multiplexing (DWDM) and the elimination of optical-electrical-optical conversions have brought on advances in communication speeds as we move into 10 Gigabit Ethernet and above. Of course, there is a need to encrypt data on these optical links as the data traverses public and private network backbones. Unfortunately, as the communications infrastructure becomes increasingly optical, advances in encryption (done electronically) have failed to keep up. This project examines the use of optical logic for implementing encryption in the photonic domain to achieve the requisite encryption rates. This paper documents the innovations and advances of work first detailed in 'Photonic Encryption using All Optical Logic,' [1]. A discussion of underlying concepts can be found in SAND2003-4474. In order to realize photonic encryption designs, technology developed for electrical logic circuits must be translated to the photonic regime. This paper examines S-SEED devices and how discrete logic elements can be interconnected and cascaded to form an optical circuit. Because there is no known software that can model these devices at a circuit level, the functionality of S-SEED devices in an optical circuit was modeled in PSpice. PSpice allows modeling of the macro characteristics of the devices in context of a logic element as opposed to device level computational modeling. By representing light intensity as voltage, 'black box' models are generated that accurately represent the intensity response and logic levels in both technologies. By modeling the behavior at the systems level, one can incorporate systems design tools and a simulation environment to aid in the overall functional design. Each black box model takes certain parameters (reflectance, intensity, input response), and models the optical ripple
Directory of Open Access Journals (Sweden)
Jeffrey W Eaton
Full Text Available Many mathematical models have investigated the impact of expanding access to antiretroviral therapy (ART on new HIV infections. Comparing results and conclusions across models is challenging because models have addressed slightly different questions and have reported different outcome metrics. This study compares the predictions of several mathematical models simulating the same ART intervention programmes to determine the extent to which models agree about the epidemiological impact of expanded ART.Twelve independent mathematical models evaluated a set of standardised ART intervention scenarios in South Africa and reported a common set of outputs. Intervention scenarios systematically varied the CD4 count threshold for treatment eligibility, access to treatment, and programme retention. For a scenario in which 80% of HIV-infected individuals start treatment on average 1 y after their CD4 count drops below 350 cells/µl and 85% remain on treatment after 3 y, the models projected that HIV incidence would be 35% to 54% lower 8 y after the introduction of ART, compared to a counterfactual scenario in which there is no ART. More variation existed in the estimated long-term (38 y reductions in incidence. The impact of optimistic interventions including immediate ART initiation varied widely across models, maintaining substantial uncertainty about the theoretical prospect for elimination of HIV from the population using ART alone over the next four decades. The number of person-years of ART per infection averted over 8 y ranged between 5.8 and 18.7. Considering the actual scale-up of ART in South Africa, seven models estimated that current HIV incidence is 17% to 32% lower than it would have been in the absence of ART. Differences between model assumptions about CD4 decline and HIV transmissibility over the course of infection explained only a modest amount of the variation in model results.Mathematical models evaluating the impact of ART vary
Eaton, Jeffrey W; Johnson, Leigh F; Salomon, Joshua A; Bärnighausen, Till; Bendavid, Eran; Bershteyn, Anna; Bloom, David E; Cambiano, Valentina; Fraser, Christophe; Hontelez, Jan A C; Humair, Salal; Klein, Daniel J; Long, Elisa F; Phillips, Andrew N; Pretorius, Carel; Stover, John; Wenger, Edward A; Williams, Brian G; Hallett, Timothy B
2012-01-01
Many mathematical models have investigated the impact of expanding access to antiretroviral therapy (ART) on new HIV infections. Comparing results and conclusions across models is challenging because models have addressed slightly different questions and have reported different outcome metrics. This study compares the predictions of several mathematical models simulating the same ART intervention programmes to determine the extent to which models agree about the epidemiological impact of expanded ART. Twelve independent mathematical models evaluated a set of standardised ART intervention scenarios in South Africa and reported a common set of outputs. Intervention scenarios systematically varied the CD4 count threshold for treatment eligibility, access to treatment, and programme retention. For a scenario in which 80% of HIV-infected individuals start treatment on average 1 y after their CD4 count drops below 350 cells/µl and 85% remain on treatment after 3 y, the models projected that HIV incidence would be 35% to 54% lower 8 y after the introduction of ART, compared to a counterfactual scenario in which there is no ART. More variation existed in the estimated long-term (38 y) reductions in incidence. The impact of optimistic interventions including immediate ART initiation varied widely across models, maintaining substantial uncertainty about the theoretical prospect for elimination of HIV from the population using ART alone over the next four decades. The number of person-years of ART per infection averted over 8 y ranged between 5.8 and 18.7. Considering the actual scale-up of ART in South Africa, seven models estimated that current HIV incidence is 17% to 32% lower than it would have been in the absence of ART. Differences between model assumptions about CD4 decline and HIV transmissibility over the course of infection explained only a modest amount of the variation in model results. Mathematical models evaluating the impact of ART vary substantially in
Transient finite element modeling of functional electrical stimulation.
Filipovic, Nenad D; Peulic, Aleksandar S; Zdravkovic, Nebojsa D; Grbovic-Markovic, Vesna M; Jurisic-Skevin, Aleksandra J
2011-03-01
Transcutaneous functional electrical stimulation is commonly used for strengthening muscle. However, transient effects during stimulation are not yet well explored. The effect of an amplitude change of the stimulation can be described by static model, but there is no differency for different pulse duration. The aim of this study is to present the finite element (FE) model of a transient electrical stimulation on the forearm. Discrete FE equations were derived by using a standard Galerkin procedure. Different tissue conductive and dielectric properties are fitted using least square method and trial and error analysis from experimental measurement. This study showed that FE modeling of electrical stimulation can give the spatial-temporal distribution of applied current in the forearm. Three different cases were modeled with the same geometry but with different input of the current pulse, in order to fit the tissue properties by using transient FE analysis. All three cases were compared with experimental measurements of intramuscular voltage on one volunteer.
Computation of Schenberg response function by using finite element modelling
International Nuclear Information System (INIS)
Frajuca, C; Bortoli, F S; Magalhaes, N S
2016-01-01
Schenberg is a detector of gravitational waves resonant mass type, with a central frequency of operation of 3200 Hz. Transducers located on the surface of the resonating sphere, according to a distribution half-dodecahedron, are used to monitor a strain amplitude. The development of mechanical impedance matchers that act by increasing the coupling of the transducers with the sphere is a major challenge because of the high frequency and small in size. The objective of this work is to study the Schenberg response function obtained by finite element modeling (FEM). Finnaly, the result is compared with the result of the simplified model for mass spring type system modeling verifying if that is suitable for the determination of sensitivity detector, as the conclusion the both modeling give the same results. (paper)
A Tensor Statistical Model for Quantifying Dynamic Functional Connectivity.
Zhu, Yingying; Zhu, Xiaofeng; Kim, Minjeong; Yan, Jin; Wu, Guorong
2017-06-01
Functional connectivity (FC) has been widely investigated in many imaging-based neuroscience and clinical studies. Since functional Magnetic Resonance Image (MRI) signal is just an indirect reflection of brain activity, it is difficult to accurately quantify the FC strength only based on signal correlation. To address this limitation, we propose a learning-based tensor model to derive high sensitivity and specificity connectome biomarkers at the individual level from resting-state fMRI images. First, we propose a learning-based approach to estimate the intrinsic functional connectivity. In addition to the low level region-to-region signal correlation, latent module-to-module connection is also estimated and used to provide high level heuristics for measuring connectivity strength. Furthermore, sparsity constraint is employed to automatically remove the spurious connections, thus alleviating the issue of searching for optimal threshold. Second, we integrate our learning-based approach with the sliding-window technique to further reveal the dynamics of functional connectivity. Specifically, we stack the functional connectivity matrix within each sliding window and form a 3D tensor where the third dimension denotes for time. Then we obtain dynamic functional connectivity (dFC) for each individual subject by simultaneously estimating the within-sliding-window functional connectivity and characterizing the across-sliding-window temporal dynamics. Third, in order to enhance the robustness of the connectome patterns extracted from dFC, we extend the individual-based 3D tensors to a population-based 4D tensor (with the fourth dimension stands for the training subjects) and learn the statistics of connectome patterns via 4D tensor analysis. Since our 4D tensor model jointly (1) optimizes dFC for each training subject and (2) captures the principle connectome patterns, our statistical model gains more statistical power of representing new subject than current state
Quadratic inference functions in marginal models for longitudinal data.
Song, Peter X-K; Jiang, Zhichang; Park, Eunjoo; Qu, Annie
2009-12-20
The quadratic inference function (QIF) is a new statistical methodology developed for the estimation and inference in longitudinal data analysis using marginal models. This method is an alternative to the popular generalized estimating equations approach, and it has several useful properties such as robustness, a goodness-of-fit test and model selection. This paper presents an introductory review of the QIF, with a strong emphasis on its applications. In particular, a recently developed SAS MACRO QIF is illustrated in this paper to obtain numerical results.
Mouse Models of Allergic Diseases: TSLP and Its Functional Roles
Directory of Open Access Journals (Sweden)
Miyuki Omori-Miyake
2012-01-01
Full Text Available The cytokine TSLP was originally identified in a murine thymic stromal cell line as a lymphoid growth factor. After the discovery of TSLP, extensive molecular genetic analyses and gene targeting experiments have demonstrated that TSLP plays an essential role in allergic diseases. In this review, we discuss the current status of TSLP and its functional role in allergic diseases particularly by focusing on effects of TSLP on haematopoietic cells in mouse models. It is our conclusion that a number of research areas, i.e., a new source of TSLP, effects of TSLP on non-haematopoietic and haematopoietic cells, synergistic interactions of cytokines including IL-25 and IL-33 and a regulation of TSLP expression and its function, are critically needed to understand the whole picture of TSLP involvement in allergic diseases. The mouse models will thus contribute further to our understanding of TSLP involvement in allergic diseases and development of therapeutic measures for human allergic diseases.
Potts model partition functions on two families of fractal lattices
Gong, Helin; Jin, Xian'an
2014-11-01
The partition function of q-state Potts model, or equivalently the Tutte polynomial, is computationally intractable for regular lattices. The purpose of this paper is to compute partition functions of q-state Potts model on two families of fractal lattices. Based on their self-similar structures and by applying the subgraph-decomposition method, we divide their Tutte polynomials into two summands, and for each summand we obtain a recursive formula involving the other summand. As a result, the number of spanning trees and their asymptotic growth constants, and a lower bound of the number of connected spanning subgraphs or acyclic root-connected orientations for each of such two lattices are obtained.
The Use of Modeling Approach for Teaching Exponential Functions
Nunes, L. F.; Prates, D. B.; da Silva, J. M.
2017-12-01
This work presents a discussion related to the teaching and learning of mathematical contents related to the study of exponential functions in a freshman students group enrolled in the first semester of the Science and Technology Bachelor’s (STB of the Federal University of Jequitinhonha and Mucuri Valleys (UFVJM). As a contextualization tool strongly mentioned in the literature, the modelling approach was used as an educational teaching tool to produce contextualization in the teaching-learning process of exponential functions to these students. In this sense, were used some simple models elaborated with the GeoGebra software and, to have a qualitative evaluation of the investigation and the results, was used Didactic Engineering as a methodology research. As a consequence of this detailed research, some interesting details about the teaching and learning process were observed, discussed and described.
Thermal shock analysis of functionally graded materials by micromechanical model
International Nuclear Information System (INIS)
Ueda, Sei
2002-01-01
The transient thermoelastic behavior of the functionally graded plate due to a thermal shock with temperature dependent properties is studied in this paper. The development of a micromechanical model for the functionally graded materials is presented and its application to thermoelastic analysis is discussed for the case of the W-Cu functionally graded material for the International Thermonuclear Experimental Reactor divertor plate. The divertor plate is made of a graded layer bonded between a homogeneous substrate and a homogeneous coating, and it is subjected to a cycle of heating and cooling on the coating surface of the material. The thermal and elastic properties of the material are dependent on the temperature and the position. Numerical calculations are carried out, and the results for the transient temperature and thermal stress distributions are displayed graphically. (author)
A review of function modeling: Approaches and applications
Erden, M.S.; Komoto, H.; Van Beek, T.J.; D'Amelio, V.; Echavarria, E.; Tomiyama, T.
2008-01-01
This work is aimed at establishing a common frame and understanding of function modeling (FM) for our ongoing research activities. A comparative review of the literature is performed to grasp the various FM approaches with their commonalities and differences. The relations of FM with the research fields of artificial intelligence, design theory, and maintenance are discussed. In this discussion the goals are to highlight the features of various classical approaches in relation to FM, to delin...
Using computational models to relate structural and functional brain connectivity
Czech Academy of Sciences Publication Activity Database
Hlinka, Jaroslav; Coombes, S.
2012-01-01
Roč. 36, č. 2 (2012), s. 2137-2145 ISSN 0953-816X R&D Projects: GA MŠk 7E08027 EU Projects: European Commission(XE) 200728 - BRAINSYNC Institutional research plan: CEZ:AV0Z10300504 Keywords : brain disease * computational modelling * functional connectivity * graph theory * structural connectivity Subject RIV: FH - Neurology Impact factor: 3.753, year: 2012
Unsteady Aerodynamic Modeling of A Maneuvering Aircraft Using Indicial Functions
2016-03-30
Paper Undergraduate Student Paper Postgraduate Student Paper █ Unsteady Aerodynamic Modeling of A Maneuvering Aircraft Using Indicial Functions...this configuration exhibit strong pitch up behaviour at a relatively low angle of attack and lateral instability that can lead to serious aerodynamic...reduce flight speed, the reduced flight speed helps to have a smaller radius turn and total travelled time. Next, the airplane starts to roll as the
Model Complexities of Shallow Networks Representing Highly Varying Functions
Czech Academy of Sciences Publication Activity Database
Kůrková, Věra; Sanguineti, M.
2016-01-01
Roč. 171, 1 January (2016), s. 598-604 ISSN 0925-2312 R&D Projects: GA MŠk(CZ) LD13002 Grant - others:grant for Visiting Professors(IT) GNAMPA-INdAM Institutional support: RVO:67985807 Keywords : shallow networks * model complexity * highly varying functions * Chernoff bound * perceptrons * Gaussian kernel units Subject RIV: IN - Informatics, Computer Science Impact factor: 3.317, year: 2016
Di Maggio, Jimena; Fernández, Carolina; Parodi, Elisa R; Diaz, M Soledad; Estrada, Vanina
2016-01-01
In this paper we address the formulation of two mechanistic water quality models that differ in the way the phytoplankton community is described. We carry out parameter estimation subject to differential-algebraic constraints and validation for each model and comparison between models performance. The first approach aggregates phytoplankton species based on their phylogenetic characteristics (Taxonomic group model) and the second one, on their morpho-functional properties following Reynolds' classification (Functional group model). The latter approach takes into account tolerance and sensitivity to environmental conditions. The constrained parameter estimation problems are formulated within an equation oriented framework, with a maximum likelihood objective function. The study site is Paso de las Piedras Reservoir (Argentina), which supplies water for consumption for 450,000 population. Numerical results show that phytoplankton morpho-functional groups more closely represent each species growth requirements within the group. Each model performance is quantitatively assessed by three diagnostic measures. Parameter estimation results for seasonal dynamics of the phytoplankton community and main biogeochemical variables for a one-year time horizon are presented and compared for both models, showing the functional group model enhanced performance. Finally, we explore increasing nutrient loading scenarios and predict their effect on phytoplankton dynamics throughout a one-year time horizon. Copyright © 2015 Elsevier Ltd. All rights reserved.
Linking density functional and mode coupling models for supercooled liquids.
Premkumar, Leishangthem; Bidhoodi, Neeta; Das, Shankar P
2016-03-28
We compare predictions from two familiar models of the metastable supercooled liquid, respectively, constructed with thermodynamic and dynamic approaches. In the so called density functional theory the free energy F[ρ] of the liquid is a functional of the inhomogeneous density ρ(r). The metastable state is identified as a local minimum of F[ρ]. The sharp density profile characterizing ρ(r) is identified as a single particle oscillator, whose frequency is obtained from the parameters of the optimum density function. On the other hand, a dynamic approach to supercooled liquids is taken in the mode coupling theory (MCT) which predict a sharp ergodicity-non-ergodicity transition at a critical density. The single particle dynamics in the non-ergodic state, treated approximately, represents a propagating mode whose characteristic frequency is computed from the corresponding memory function of the MCT. The mass localization parameters in the above two models (treated in their simplest forms) are obtained, respectively, in terms of the corresponding natural frequencies depicted and are shown to have comparable magnitudes.
Linking density functional and mode coupling models for supercooled liquids
Energy Technology Data Exchange (ETDEWEB)
Premkumar, Leishangthem; Bidhoodi, Neeta; Das, Shankar P. [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)
2016-03-28
We compare predictions from two familiar models of the metastable supercooled liquid, respectively, constructed with thermodynamic and dynamic approaches. In the so called density functional theory the free energy F[ρ] of the liquid is a functional of the inhomogeneous density ρ(r). The metastable state is identified as a local minimum of F[ρ]. The sharp density profile characterizing ρ(r) is identified as a single particle oscillator, whose frequency is obtained from the parameters of the optimum density function. On the other hand, a dynamic approach to supercooled liquids is taken in the mode coupling theory (MCT) which predict a sharp ergodicity-non-ergodicity transition at a critical density. The single particle dynamics in the non-ergodic state, treated approximately, represents a propagating mode whose characteristic frequency is computed from the corresponding memory function of the MCT. The mass localization parameters in the above two models (treated in their simplest forms) are obtained, respectively, in terms of the corresponding natural frequencies depicted and are shown to have comparable magnitudes.
Calibration of two complex ecosystem models with different likelihood functions
Hidy, Dóra; Haszpra, László; Pintér, Krisztina; Nagy, Zoltán; Barcza, Zoltán
2014-05-01
The biosphere is a sensitive carbon reservoir. Terrestrial ecosystems were approximately carbon neutral during the past centuries, but they became net carbon sinks due to climate change induced environmental change and associated CO2 fertilization effect of the atmosphere. Model studies and measurements indicate that the biospheric carbon sink can saturate in the future due to ongoing climate change which can act as a positive feedback. Robustness of carbon cycle models is a key issue when trying to choose the appropriate model for decision support. The input parameters of the process-based models are decisive regarding the model output. At the same time there are several input parameters for which accurate values are hard to obtain directly from experiments or no local measurements are available. Due to the uncertainty associated with the unknown model parameters significant bias can be experienced if the model is used to simulate the carbon and nitrogen cycle components of different ecosystems. In order to improve model performance the unknown model parameters has to be estimated. We developed a multi-objective, two-step calibration method based on Bayesian approach in order to estimate the unknown parameters of PaSim and Biome-BGC models. Biome-BGC and PaSim are a widely used biogeochemical models that simulate the storage and flux of water, carbon, and nitrogen between the ecosystem and the atmosphere, and within the components of the terrestrial ecosystems (in this research the developed version of Biome-BGC is used which is referred as BBGC MuSo). Both models were calibrated regardless the simulated processes and type of model parameters. The calibration procedure is based on the comparison of measured data with simulated results via calculating a likelihood function (degree of goodness-of-fit between simulated and measured data). In our research different likelihood function formulations were used in order to examine the effect of the different model
A dynamic model for functional mapping of biological rhythms.
Fu, Guifang; Luo, Jiangtao; Berg, Arthur; Wang, Zhong; Li, Jiahan; Das, Kiranmoy; Li, Runze; Wu, Rongling
2011-01-01
Functional mapping is a statistical method for mapping quantitative trait loci (QTLs) that regulate the dynamic pattern of a biological trait. This method integrates mathematical aspects of biological complexity into a mixture model for genetic mapping and tests the genetic effects of QTLs by comparing genotype-specific curve parameters. As a way of quantitatively specifying the dynamic behavior of a system, differential equations have proven to be powerful for modeling and unraveling the biochemical, molecular, and cellular mechanisms of a biological process, such as biological rhythms. The equipment of functional mapping with biologically meaningful differential equations provides new insights into the genetic control of any dynamic processes. We formulate a new functional mapping framework for a dynamic biological rhythm by incorporating a group of ordinary differential equations (ODE). The Runge-Kutta fourth order algorithm was implemented to estimate the parameters that define the system of ODE. The new model will find its implications for understanding the interplay between gene interactions and developmental pathways in complex biological rhythms.
Modeling Marine Electromagnetic Survey with Radial Basis Function Networks
Directory of Open Access Journals (Sweden)
Agus Arif
2014-11-01
Full Text Available A marine electromagnetic survey is an engineering endeavour to discover the location and dimension of a hydrocarbon layer under an ocean floor. In this kind of survey, an array of electric and magnetic receivers are located on the sea floor and record the scattered, refracted and reflected electromagnetic wave, which has been transmitted by an electric dipole antenna towed by a vessel. The data recorded in receivers must be processed and further analysed to estimate the hydrocarbon location and dimension. To conduct those analyses successfuly, a radial basis function (RBF network could be employed to become a forward model of the input-output relationship of the data from a marine electromagnetic survey. This type of neural networks is working based on distances between its inputs and predetermined centres of some basis functions. A previous research had been conducted to model the same marine electromagnetic survey using another type of neural networks, which is a multi layer perceptron (MLP network. By comparing their validation and training performances (mean-squared errors and correlation coefficients, it is concluded that, in this case, the MLP network is comparatively better than the RBF network[1].[1] This manuscript is an extended version of our previous paper, entitled Radial Basis Function Networks for Modeling Marine Electromagnetic Survey, which had been presented on 2011 International Conference on Electrical Engineering and Informatics, 17-19 July 2011, Bandung, Indonesia.
Batterham, A M; George, K P
1997-12-01
In the exercise sciences, simple allometry (y = axb) is rapidly becoming the method of choice for scaling physiological and human performance data for differences in body size. The purpose of this study is to detail the specific regression diagnostics required to validate such models. The sum (T, in kg) of the "snatch" and "clean-and-jerk" lifts of the medalists from the 1995 Men's and Women's World Weightlifting Championships was modeled as a function of body mass (M, in kg). A log-linearized allometric model (ln T = ln a + b ln M) yielded a common mass exponent (b) of 0. 47 (95% confidence interval = 0.43-0.51, P < 0.01). However, size-related patterned deviations in the residuals were evident, indicating that the allometric model was poorly specified and that the mass exponent was not size independent. Model respecification revealed that second-order polynomials provided the best fit, supporting previous modeling of weightlifting data (R. G. Sinclair. Can. J. Appl. Sport Sci. 10: 94-98, 1985). The model parameters (means +/- SE) were T = (21.48 +/- 16.55) + (6.119 +/- 0.359)M - (0. 022 +/- 0.002)M2 (R2 = 0.97) for men and T = (-20.73 +/- 24.14) + (5. 662 +/- 0.722)M - (0.031 +/- 0.005)M2 (R2 = 0.92) for women. We conclude that allometric scaling should be applied only when all underlying model assumptions have been rigorously evaluated.
Directory of Open Access Journals (Sweden)
Gerhard Visser
2012-09-01
Full Text Available We investigated the application of a Minimum Message Length (MML modeling approach to identify the simplest model that would explain two target malaria incidence variables: incidence in the short term and on the average longer term, in two areas in Indonesia, based on a range of ecological variables including environmental and socio-economic ones. The approach is suitable for dealing with a variety of problems such as complexity and where there are missing values in the data. It can detect weak relations, is resistant to overfittingand can show the way in which many variables, working together, contribute to explaining malaria incidence. This last point is a major strength of the method as it allows many variables to be analysed. Data were obtained at household level by questionnaire for villages in West Timor and Central Java. Data were collected on 26 variables in nine categories: stratum (a village-level variable based on the API/AMI categories, ecology, occupation, preventative measures taken, health care facilities, the immediate environment, household characteristics, socio-economic status and perception of malaria cause. Several models were used and the simplest (best model, that is the one with the minimum message length was selected for each area. The results showed that consistent predictors of malaria included combinations of ecology (coastal, preventative (clean backyard and environment (mosquito breeding place, garden and rice cultivation. The models also showed that most of the other variables were not good predictors and this is discussed in the paper. We conclude that the method has potential for identifying simple predictors of malaria and that it could be used to focus malaria management on combinations of variables rather than relying on single ones that may not be consistently reliable.
Team models in neurorehabilitation: structure, function, and culture change.
Karol, Robert L
2014-01-01
Neurorehabilitation requires a team effort. Over time the nature of teams has evolved from single discipline work through multi-disciplinary and inter-disciplinary teams to trans-disciplinary teams. However, there are inconsistencies in the literature and clinical practice as to the structure and function of these team models. Each model engenders advantages over its predecessor and unless the models are well understood clinicians may labor in a model that is less efficacious than the most transcendent model. To define and examine the models of single discipline care, multi-disciplinary teams, inter-disciplinary teams, and trans-disciplinary teams and to review in depth trans-disciplinary teams as the most advanced team model. This paper will also consider professional roles and integration across disciplines as well as the crucial topics of staff selection, attendance in rounds and the nature of rounds, staff physical plant assignments, and leadership responsibilities. Leadership responsibilities that will be addressed include scope of practice and role release, peer pressure, and culture change issues. The trans-disciplinary model is the gold standard for teams in neurorehabilitation because they entail more integrated service delivery than do other teams. Trans-disciplinary teams also represent a more persons-centered approach. To initiate a trans-disciplinary model, team members must have excellent communication and shared decision making including persons with brain injury. Leadership must address staff selection, scope of practice and role-release. Otherwise, the model will fail due to peer pressure and institutional or program cultural variables.
Gaussian copula as a likelihood function for environmental models
Wani, O.; Espadas, G.; Cecinati, F.; Rieckermann, J.
2017-12-01
Parameter estimation of environmental models always comes with uncertainty. To formally quantify this parametric uncertainty, a likelihood function needs to be formulated, which is defined as the probability of observations given fixed values of the parameter set. A likelihood function allows us to infer parameter values from observations using Bayes' theorem. The challenge is to formulate a likelihood function that reliably describes the error generating processes which lead to the observed monitoring data, such as rainfall and runoff. If the likelihood function is not representative of the error statistics, the parameter inference will give biased parameter values. Several uncertainty estimation methods that are currently being used employ Gaussian processes as a likelihood function, because of their favourable analytical properties. Box-Cox transformation is suggested to deal with non-symmetric and heteroscedastic errors e.g. for flow data which are typically more uncertain in high flows than in periods with low flows. Problem with transformations is that the results are conditional on hyper-parameters, for which it is difficult to formulate the analyst's belief a priori. In an attempt to address this problem, in this research work we suggest learning the nature of the error distribution from the errors made by the model in the "past" forecasts. We use a Gaussian copula to generate semiparametric error distributions . 1) We show that this copula can be then used as a likelihood function to infer parameters, breaking away from the practice of using multivariate normal distributions. Based on the results from a didactical example of predicting rainfall runoff, 2) we demonstrate that the copula captures the predictive uncertainty of the model. 3) Finally, we find that the properties of autocorrelation and heteroscedasticity of errors are captured well by the copula, eliminating the need to use transforms. In summary, our findings suggest that copulas are an
Colour-independent partition functions in coloured vertex models
Energy Technology Data Exchange (ETDEWEB)
Foda, O., E-mail: omar.foda@unimelb.edu.au [Dept. of Mathematics and Statistics, University of Melbourne, Parkville, VIC 3010 (Australia); Wheeler, M., E-mail: mwheeler@lpthe.jussieu.fr [Laboratoire de Physique Théorique et Hautes Energies, CNRS UMR 7589 (France); Université Pierre et Marie Curie – Paris 6, 4 place Jussieu, 75252 Paris cedex 05 (France)
2013-06-11
We study lattice configurations related to S{sub n}, the scalar product of an off-shell state and an on-shell state in rational A{sub n} integrable vertex models, n∈{1,2}. The lattice lines are colourless and oriented. The state variables are n conserved colours that flow along the line orientations, but do not necessarily cover every bond in the lattice. Choosing boundary conditions such that the positions where the colours flow into the lattice are fixed, and where they flow out are summed over, we show that the partition functions of these configurations, with these boundary conditions, are n-independent. Our results extend to trigonometric A{sub n} models, and to all n. This n-independence explains, in vertex-model terms, results from recent studies of S{sub 2} (Caetano and Vieira, 2012, [1], Wheeler, (arXiv:1204.2089), [2]). Namely, 1.S{sub 2}, which depends on two sets of Bethe roots, {b_1} and {b_2}, and cannot (as far as we know) be expressed in single determinant form, degenerates in the limit {b_1}→∞, and/or {b_2}→∞, into a product of determinants, 2. Each of the latter determinants is an A{sub 1} vertex-model partition function.
Colour-independent partition functions in coloured vertex models
International Nuclear Information System (INIS)
Foda, O.; Wheeler, M.
2013-01-01
We study lattice configurations related to S n , the scalar product of an off-shell state and an on-shell state in rational A n integrable vertex models, n∈{1,2}. The lattice lines are colourless and oriented. The state variables are n conserved colours that flow along the line orientations, but do not necessarily cover every bond in the lattice. Choosing boundary conditions such that the positions where the colours flow into the lattice are fixed, and where they flow out are summed over, we show that the partition functions of these configurations, with these boundary conditions, are n-independent. Our results extend to trigonometric A n models, and to all n. This n-independence explains, in vertex-model terms, results from recent studies of S 2 (Caetano and Vieira, 2012, [1], Wheeler, (arXiv:1204.2089), [2]). Namely, 1.S 2 , which depends on two sets of Bethe roots, {b 1 } and {b 2 }, and cannot (as far as we know) be expressed in single determinant form, degenerates in the limit {b 1 }→∞, and/or {b 2 }→∞, into a product of determinants, 2. Each of the latter determinants is an A 1 vertex-model partition function
Plant lessons: exploring ABCB functionality through structural modeling
Directory of Open Access Journals (Sweden)
Aurélien eBailly
2012-01-01
Full Text Available In contrast to mammalian ABCB1 proteins, narrow substrate specificity has been extensively documented for plant orthologs shown to catalyze the transport of the plant hormone, auxin. Using the crystal structures of the multidrug exporters Sav1866 and MmABCB1 as templates, we have developed structural models of plant ABCB proteins with a common architecture. Comparisons of these structures identified kingdom-specific candidate substrate-binding regions within the translocation chamber formed by the transmembrane domains of ABCBs from the model plant Arabidopsis. These results suggest an early evolutionary divergence of plant and mammalian ABCBs. Validation of these models becomes a priority for efforts to elucidate ABCB function and manipulate this class of transporters to enhance plant productivity and quality.
Plant Lessons: Exploring ABCB Functionality Through Structural Modeling
Bailly, Aurélien; Yang, Haibing; Martinoia, Enrico; Geisler, Markus; Murphy, Angus S.
2012-01-01
In contrast to mammalian ABCB1 proteins, narrow substrate specificity has been extensively documented for plant orthologs shown to catalyze the transport of the plant hormone, auxin. Using the crystal structures of the multidrug exporters Sav1866 and MmABCB1 as templates, we have developed structural models of plant ABCB proteins with a common architecture. Comparisons of these structures identified kingdom-specific candidate substrate-binding regions within the translocation chamber formed by the transmembrane domains of ABCBs from the model plant Arabidopsis. These results suggest an early evolutionary divergence of plant and mammalian ABCBs. Validation of these models becomes a priority for efforts to elucidate ABCB function and manipulate this class of transporters to enhance plant productivity and quality. PMID:22639627
Simple model for low-frequency guitar function
DEFF Research Database (Denmark)
Christensen, Ove; Vistisen, Bo B.
1980-01-01
- frequency guitar function. The model predicts frequency responce of sound pressure and top plate mobility which are in close quantitative agreement with experimental responses. The absolute sound pressure level and mobility level are predicted to within a few decibels, and the equivalent piston area......The frequency response of sound pressure and top plate mobility is studied around the two first resonances of the guitar. These resonances are shown to result from a coupling between the fundamental top plate mode and the Helmholtz resonance of the cavity. A simple model is proposed for low...... of the top plate is determined. All parameters of this model can directly be derived from measurements of the frequencies of the two first resonances and of the cavity Helmholtz resonance. The Helmholtz resonance is found as the antiresonance in the spectrum of top plate mobility....
Azzam, R M A
2016-10-20
Intensity reflectances and ellipsometric parameters of a partially clad transparent substrate that suppresses the reflection of incident p- and s-polarized light at the same angle of incidence from uncoated and single-layer-coated areas are determined as functions of normalized film thickness ς and substrate refractive index n2. The common polarizing angle is the Brewster angle of the ambient-substrate interface, and the light beam incident from the ambient (air or vacuum) is refracted in the film at a 45° angle from the normal to the parallel-plane film boundaries. For n2≤2, the differential reflection phase shift Δ=δp-δs≈±90° for all values of ς so that the Brewster angle is also approximately the principal angle of the film-substrate system independent of film thickness. Accurate techniques for monitoring the deposition of such films are also proposed.
Functional gait analysis in a spinal contusion rat model.
Bhimani, Abhiraj D; Kheirkhah, Pouyan; Arnone, Gregory D; Nahhas, Cindy R; Kumar, Prateek; Wonais, Matt; Hidrogo, Hugo; Aguilar, Eddy; Spalinski, Daniel; Gopalka, Mahie; Roth, Steven; Mehta, Ankit I
2017-12-01
Evaluating functional performance of spinal cord injury (SCI) rat models is essential for the development of novel treatments and breakthroughs. However, due to the variety of functional analysis methods available - each with its own strengths and weaknesses - it can be challenging to choose the most appropriate functional analysis test for the animal model. Therefore, we analyzed the strengths and weaknesses of five methods in order to determine which test is not only accurate and easily reproducible, but also relatively inexpensive so that it can be adopted universally. When comparing the Basso, Beattie, and Bresnahan (BBB) test, Ladder walking test, CatWalk test, Rotating Rod test, Microsoft Kinect system and VICON, we used the criteria of sensitivity, quality of data generated, statistical analysis of data, and rate of human error. These specific tests were chosen in order to compare the advantages and disadvantages of simple yet effective methods (BBB, Ladder test, and Rotating Rod test) to more complex and computerized methods (Catwalk, Microsoft Kinect and VICON). Copyright © 2017 Elsevier Ltd. All rights reserved.
Two-point functions in a holographic Kondo model
Energy Technology Data Exchange (ETDEWEB)
Erdmenger, Johanna [Institut für Theoretische Physik und Astrophysik, Julius-Maximilians-Universität Würzburg,Am Hubland, D-97074 Würzburg (Germany); Max-Planck-Institut für Physik (Werner-Heisenberg-Institut),Föhringer Ring 6, D-80805 Munich (Germany); Hoyos, Carlos [Department of Physics, Universidad de Oviedo, Avda. Calvo Sotelo 18, 33007, Oviedo (Spain); O’Bannon, Andy [STAG Research Centre, Physics and Astronomy, University of Southampton,Highfield, Southampton SO17 1BJ (United Kingdom); Papadimitriou, Ioannis [SISSA and INFN - Sezione di Trieste, Via Bonomea 265, I 34136 Trieste (Italy); Probst, Jonas [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Road, Oxford OX1 3NP (United Kingdom); Wu, Jackson M.S. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States)
2017-03-07
We develop the formalism of holographic renormalization to compute two-point functions in a holographic Kondo model. The model describes a (0+1)-dimensional impurity spin of a gauged SU(N) interacting with a (1+1)-dimensional, large-N, strongly-coupled Conformal Field Theory (CFT). We describe the impurity using Abrikosov pseudo-fermions, and define an SU(N)-invariant scalar operator O built from a pseudo-fermion and a CFT fermion. At large N the Kondo interaction is of the form O{sup †}O, which is marginally relevant, and generates a Renormalization Group (RG) flow at the impurity. A second-order mean-field phase transition occurs in which O condenses below a critical temperature, leading to the Kondo effect, including screening of the impurity. Via holography, the phase transition is dual to holographic superconductivity in (1+1)-dimensional Anti-de Sitter space. At all temperatures, spectral functions of O exhibit a Fano resonance, characteristic of a continuum of states interacting with an isolated resonance. In contrast to Fano resonances observed for example in quantum dots, our continuum and resonance arise from a (0+1)-dimensional UV fixed point and RG flow, respectively. In the low-temperature phase, the resonance comes from a pole in the Green’s function of the form −i〈O〉{sup 2}, which is characteristic of a Kondo resonance.
Bennani, Aziza; El-Kettani, Amina; Hançali, Amina; El-Rhilani, Houssine; Alami, Kamal; Youbi, Mohamed; Rowley, Jane; Abu-Raddad, Laith; Smolak, Alex; Taylor, Melanie; Mahiané, Guy; Stover, John; Korenromp, Eline L
2017-01-01
Evolving health priorities and resource constraints mean that countries require data on trends in sexually transmitted infections (STI) burden, to inform program planning and resource allocation. We applied the Spectrum STI estimation tool to estimate the prevalence and incidence of active syphilis in adult women in Morocco over 1995 to 2016. The results from the analysis are being used to inform Morocco's national HIV/STI strategy, target setting and program evaluation. Syphilis prevalence levels and trends were fitted through logistic regression to data from surveys in antenatal clinics, women attending family planning clinics and other general adult populations, as available post-1995. Prevalence data were adjusted for diagnostic test performance, and for the contribution of higher-risk populations not sampled in surveys. Incidence was inferred from prevalence by adjusting for the average duration of infection with active syphilis. In 2016, active syphilis prevalence was estimated to be 0.56% in women 15 to 49 years of age (95% confidence interval, CI: 0.3%-1.0%), and around 21,675 (10,612-37,198) new syphilis infections have occurred. The analysis shows a steady decline in prevalence from 1995, when the prevalence was estimated to be 1.8% (1.0-3.5%). The decline was consistent with decreasing prevalences observed in TB patients, fishermen and prisoners followed over 2000-2012 through sentinel surveillance, and with a decline since 2003 in national HIV incidence estimated earlier through independent modelling. Periodic population-based surveys allowed Morocco to estimate syphilis prevalence and incidence trends. This first-ever undertaking engaged and focused national stakeholders, and confirmed the still considerable syphilis burden. The latest survey was done in 2012 and so the trends are relatively uncertain after 2012. From 2017 Morocco plans to implement a system to record data from routine antenatal programmatic screening, which should help update and re
Energy Technology Data Exchange (ETDEWEB)
Smith, D; Debeb, B; Larson, R; Diagaradjane, P; Woodward, W [MD Anderson Cancer Center, Houston, TX (United States)
2015-06-15
Purpose: Prophylactic cranial irradiation (PCI) is a clinical technique used to reduce the incidence of brain metastasis and improve overall survival in select patients with acute lymphoblastic leukemia and small-cell lung cancer. We examined whether PCI could benefit breast cancer patients at high risk of developing brain metastases. Methods: We utilized our mouse model in which 500k green fluorescent protein (GFP)-labeled breast cancer cells injected into the tail vein of SCID/Beige mice resulted in brain metastases in approximately two-thirds of untreated mice. To test the efficacy of PCI, one set of mice was irradiated five days after cell injection with a single fraction of 4-Gy (two 2-Gy opposing fields) whole-brain irradiation on the XRAD 225Cx small-animal irradiator. Four controls were included: a non-irradiated group, a group irradiated two days prior to cell injection, and two groups irradiated 3 or 6 weeks after cell injection. Mice were sacrificed four and eight weeks post-injection and were evaluated for the presence of brain metastases on a fluorescent stereomicroscope. Results: The incidence of brain metastasis in the non-irradiated group was 77% and 90% at four and eight weeks, respectively. The PCI group had a significantly lower incidence, 20% and 30%, whereas the other three control groups had incidence rates similar to the non-treated control (70% to 100%). Further, the number of metastases and the metastatic burden were also significantly lower in the PCI group compared to all other groups. Conclusion: The timing of irradiation to treat subclinical disease is critical, as a small dose of whole-brain irradiation given five days after cell injection abrogated tumor burden by greater than 90%, but had no effect when administered twenty-one days after cell injection. PCI is likely to benefit breast cancer patients at high risk of developing brain metastases and should be strongly considered in the clinic.
2013-01-01
Background The information of electromyographic signals can be used by Myoelectric Control Systems (MCSs) to actuate prostheses. These devices allow the performing of movements that cannot be carried out by persons with amputated limbs. The state of the art in the development of MCSs is based on the use of individual principal component analysis (iPCA) as a stage of pre-processing of the classifiers. The iPCA pre-processing implies an optimization stage which has not yet been deeply explored. Methods The present study considers two factors in the iPCA stage: namely A (the fitness function), and B (the search algorithm). The A factor comprises two levels, namely A1 (the classification error) and A2 (the correlation factor). Otherwise, the B factor has four levels, specifically B1 (the Sequential Forward Selection, SFS), B2 (the Sequential Floating Forward Selection, SFFS), B3 (Artificial Bee Colony, ABC), and B4 (Particle Swarm Optimization, PSO). This work evaluates the incidence of each one of the eight possible combinations between A and B factors over the classification error of the MCS. Results A two factor ANOVA was performed on the computed classification errors and determined that: (1) the interactive effects over the classification error are not significative (F0.01,3,72 = 4.0659 > f AB = 0.09), (2) the levels of factor A have significative effects on the classification error (F0.02,1,72 = 5.0162 f B = 0.08). Conclusions Considering the classification performance we found a superiority of using the factor A2 in combination with any of the levels of factor B. With respect to the time performance the analysis suggests that the PSO algorithm is at least 14 percent better than its best competitor. The latter behavior has been observed for a particular configuration set of parameters in the search algorithms. Future works will investigate the effect of these parameters in the classification performance, such as length of the reduced
Evaluation of a modified rat model for functional dyspepsia.
Liang, Qiankun; Yan, Yuan; Mao, Lanfang; Du, Xiaojuan; Liang, Jingjing; Liu, Junhong; Wang, Longde; Li, Hongfang
2018-04-13
The purpose of this study was to establish a modified rat model with functional dyspepsia (FD) and analyze the changes in gastrointestinal motility and brain-gut peptide levels in serum and brain-gut axis. Male Wistar rats were divided into control group (Con) and FD model group. FD model was established by stimulating semi-starvation rats via tail damping, provocation, and forced exercise fatigue until gastrointestinal motility disorder appeared, and then levels of motilin, leptin, cholecystokinin (CCK), and vasoactive intestinal peptide (VIP) were detected in serum by enzyme linked immunosorbent assay and in duodenum, antrum, and hypothalamus by immunohistochemistry, reverse transcriptase-polymerase chain reaction, and Western blot. The results showed rates of intestinal propulsion and gastric emptying slowed down markedly compared to Con (P < 0.05), the gastrointestinal electric activity attenuated, and migrating motor complex (MMC) interrupted in the model group. The levels of leptin and VIP markedly increased, but motilin decreased as compared to the Con (P < 0.05) in serum and in the above tissues. It is interesting that the level of CCK decreased in the antrum and duodenum but increased in the hypothalamus as compared to Con (P < 0.05). The modified rat model meets the diagnostic criteria of FD and can be used as a method for studying FD in animals.
Functional networks inference from rule-based machine learning models.
Lazzarini, Nicola; Widera, Paweł; Williamson, Stuart; Heer, Rakesh; Krasnogor, Natalio; Bacardit, Jaume
2016-01-01
Functional networks play an important role in the analysis of biological processes and systems. The inference of these networks from high-throughput (-omics) data is an area of intense research. So far, the similarity-based inference paradigm (e.g. gene co-expression) has been the most popular approach. It assumes a functional relationship between genes which are expressed at similar levels across different samples. An alternative to this paradigm is the inference of relationships from the structure of machine learning models. These models are able to capture complex relationships between variables, that often are different/complementary to the similarity-based methods. We propose a protocol to infer functional networks from machine learning models, called FuNeL. It assumes, that genes used together within a rule-based machine learning model to classify the samples, might also be functionally related at a biological level. The protocol is first tested on synthetic datasets and then evaluated on a test suite of 8 real-world datasets related to human cancer. The networks inferred from the real-world data are compared against gene co-expression networks of equal size, generated with 3 different methods. The comparison is performed from two different points of view. We analyse the enriched biological terms in the set of network nodes and the relationships between known disease-associated genes in a context of the network topology. The comparison confirms both the biological relevance and the complementary character of the knowledge captured by the FuNeL networks in relation to similarity-based methods and demonstrates its potential to identify known disease associations as core elements of the network. Finally, using a prostate cancer dataset as a case study, we confirm that the biological knowledge captured by our method is relevant to the disease and consistent with the specialised literature and with an independent dataset not used in the inference process. The
Analyzing availability using transfer function models and cross spectral analysis
International Nuclear Information System (INIS)
Singpurwalla, N.D.
1980-01-01
The paper shows how the methods of multivariate time series analysis can be used in a novel way to investigate the interrelationships between a series of operating (running) times and a series of maintenance (down) times of a complex system. Specifically, the techniques of cross spectral analysis are used to help obtain a Box-Jenkins type transfer function model for the running times and the down times of a nuclear reactor. A knowledge of the interrelationships between the running times and the down times is useful for an evaluation of maintenance policies, for replacement policy decisions, and for evaluating the availability and the readiness of complex systems
Bidirectional Texture Function Modeling: State of the Art Survey
Czech Academy of Sciences Publication Activity Database
Filip, Jiří; Haindl, Michal
2009-01-01
Roč. 31, č. 11 (2009), s. 1921-1940 ISSN 0162-8828 R&D Projects: GA MŠk 1M0572; GA ČR GA102/08/0593; GA AV ČR 1ET400750407 Grant - others:EC Marie Curie(BE) 41358; GA MŠk(CZ) 2C06019 Institutional research plan: CEZ:AV0Z10750506 Keywords : BTF * surface texture * 3D texture Subject RIV: BD - Theory of Information Impact factor: 4.378, year: 2009 http://library.utia.cas.cz/separaty/2009/RO/filip-bidirectional texture function modeling state of the art survey.pdf
Lu, Yi; Haverkort, Maurits W.
2017-12-01
We present a nonperturbative, divergence-free series expansion of Green's functions using effective operators. The method is especially suited for computing correlators of complex operators as a series of correlation functions of simpler forms. We apply the method to study low-energy excitations in resonant inelastic x-ray scattering (RIXS) in doped one- and two-dimensional single-band Hubbard models. The RIXS operator is expanded into polynomials of spin, density, and current operators weighted by fundamental x-ray spectral functions. These operators couple to different polarization channels resulting in simple selection rules. The incident photon energy dependent coefficients help to pinpoint main RIXS contributions from different degrees of freedom. We show in particular that, with parameters pertaining to cuprate superconductors, local spin excitation dominates the RIXS spectral weight over a wide doping range in the cross-polarization channel.
Approximate models for the analysis of laser velocimetry correlation functions
International Nuclear Information System (INIS)
Robinson, D.P.
1981-01-01
Velocity distributions in the subchannels of an eleven pin test section representing a slice through a Fast Reactor sub-assembly were measured with a dual beam laser velocimeter system using a Malvern K 7023 digital photon correlator for signal processing. Two techniques were used for data reduction of the correlation function to obtain velocity and turbulence values. Whilst both techniques were in excellent agreement on the velocity, marked discrepancies were apparent in the turbulence levels. As a consequence of this the turbulence data were not reported. Subsequent investigation has shown that the approximate technique used as the basis of Malvern's Data Processor 7023V is restricted in its range of application. In this note alternative approximate models are described and evaluated. The objective of this investigation was to develop an approximate model which could be used for on-line determination of the turbulence level. (author)
Structure and Function of a Nonruminant Gut: A Porcine Model
DEFF Research Database (Denmark)
Tajima, Kiyoshi; Aminov, Rustam
2015-01-01
In many aspects, the anatomical, physiological, and microbial diversity features of the ruminant gut are different from that of the monogastric animals. Thus, the main aim of this chapter is to give a comparative overview of the structure and function of the gastrointestinal tract of a nonruminant...... monogastric animal, and here it is represented by a pig model. In this chapter, we describe and discuss (i) microbial diversity in different parts of the porcine gut; (ii) differences between the ruminant and nonruminant gut; (iii) main events during colonization and succession of microbiota in the porcine...... gut; (iv) effects of various feed additives including antibiotics, phages, probiotics, and prebiotics on pigs; and (v) the use of the porcine model in translational medicine....
Dynamics Model Abstraction Scheme Using Radial Basis Functions
Directory of Open Access Journals (Sweden)
Silvia Tolu
2012-01-01
Full Text Available This paper presents a control model for object manipulation. Properties of objects and environmental conditions influence the motor control and learning. System dynamics depend on an unobserved external context, for example, work load of a robot manipulator. The dynamics of a robot arm change as it manipulates objects with different physical properties, for example, the mass, shape, or mass distribution. We address active sensing strategies to acquire object dynamical models with a radial basis function neural network (RBF. Experiments are done using a real robot’s arm, and trajectory data are gathered during various trials manipulating different objects. Biped robots do not have high force joint servos and the control system hardly compensates all the inertia variation of the adjacent joints and disturbance torque on dynamic gait control. In order to achieve smoother control and lead to more reliable sensorimotor complexes, we evaluate and compare a sparse velocity-driven versus a dense position-driven control scheme.
DEFF Research Database (Denmark)
Øjelund, Henrik; Sadegh, Payman
2000-01-01
be obtained. This paper presents a new approach for system modelling under partial (global) information (or the so called Gray-box modelling) that seeks to perserve the benefits of the global as well as local methodologies sithin a unified framework. While the proposed technique relies on local approximations......Local function approximations concern fitting low order models to weighted data in neighbourhoods of the points where the approximations are desired. Despite their generality and convenience of use, local models typically suffer, among others, from difficulties arising in physical interpretation...... simultaneously with the (local estimates of) function values. The approach is applied to modelling of a linear time variant dynamic system under prior linear time invariant structure where local regression fails as a result of high dimensionality....
Models for predicting objective function weights in prostate cancer IMRT
International Nuclear Information System (INIS)
Boutilier, Justin J.; Lee, Taewoo; Craig, Tim; Sharpe, Michael B.; Chan, Timothy C. Y.
2015-01-01
Purpose: To develop and evaluate the clinical applicability of advanced machine learning models that simultaneously predict multiple optimization objective function weights from patient geometry for intensity-modulated radiation therapy of prostate cancer. Methods: A previously developed inverse optimization method was applied retrospectively to determine optimal objective function weights for 315 treated patients. The authors used an overlap volume ratio (OV) of bladder and rectum for different PTV expansions and overlap volume histogram slopes (OVSR and OVSB for the rectum and bladder, respectively) as explanatory variables that quantify patient geometry. Using the optimal weights as ground truth, the authors trained and applied three prediction models: logistic regression (LR), multinomial logistic regression (MLR), and weighted K-nearest neighbor (KNN). The population average of the optimal objective function weights was also calculated. Results: The OV at 0.4 cm and OVSR at 0.1 cm features were found to be the most predictive of the weights. The authors observed comparable performance (i.e., no statistically significant difference) between LR, MLR, and KNN methodologies, with LR appearing to perform the best. All three machine learning models outperformed the population average by a statistically significant amount over a range of clinical metrics including bladder/rectum V53Gy, bladder/rectum V70Gy, and dose to the bladder, rectum, CTV, and PTV. When comparing the weights directly, the LR model predicted bladder and rectum weights that had, on average, a 73% and 74% relative improvement over the population average weights, respectively. The treatment plans resulting from the LR weights had, on average, a rectum V70Gy that was 35% closer to the clinical plan and a bladder V70Gy that was 29% closer, compared to the population average weights. Similar results were observed for all other clinical metrics. Conclusions: The authors demonstrated that the KNN and MLR
Modeling of fingerlike functionally graded microstructure piezoelectric actuator
Almajid, Abdulhakim; Hudnut, Steven W.; Taya, Minoru
2000-06-01
The mechanical behavior of a cylindrical, finger-like shaped, piezoelectric actuator with Functionally Graded Microstructure (FGM) was modeled by our analytical model and FEM. Different layers or lamina of different piezoelectric volume fraction in a polymer matrix were stacked to create FGM. Although the bimorph plate exhibit reasonably high out-of-plane displacement, induced stress field remains very high limiting its long life use. FGM piezoelectric plates have been developed to increase the out-of-plane displacement while reducing the stresses where the electro-elastic properties are graded through the plate thickness. Finger-like shape piezo actuators are developed where the properties are graded in the radial direction. FGM piezoelectric type actuator showed promising results in that the deflections to any direction can be obtained by manipulating the magnitude and direction of the applied electric field. Analytical modeling in computing the deflection of the finger-like actuator and stress field induced in each lamina was developed and compared to FEM modeling. The theory of cylindrical FGM is based on lamination theory in which the coordinate system is changed from the rectangular to cylindrical one and from infinite to finite plate.
DEFF Research Database (Denmark)
Steffensen, Annette Buur; Refaat, Marwan M; David, Jens-Peter
2015-01-01
The Long QT syndrome (LQTS) is a disorder characterized by a prolongation of the QT interval and a propensity to ventricular tachyarrhythmias, which may lead to syncope, cardiac arrest, or sudden death. Our objective was to (1) determine the incidence of variants with unknown significance (VUS) i...
The integrated Earth System Model Version 1: formulation and functionality
Energy Technology Data Exchange (ETDEWEB)
Collins, William D.; Craig, Anthony P.; Truesdale, John E.; Di Vittorio, Alan; Jones, Andrew D.; Bond-Lamberty, Benjamin; Calvin, Katherine V.; Edmonds, James A.; Kim, Son H.; Thomson, Allison M.; Patel, Pralit L.; Zhou, Yuyu; Mao, Jiafu; Shi, Xiaoying; Thornton, Peter E.; Chini, Louise M.; Hurtt, George C.
2015-07-23
The integrated Earth System Model (iESM) has been developed as a new tool for pro- jecting the joint human/climate system. The iESM is based upon coupling an Integrated Assessment Model (IAM) and an Earth System Model (ESM) into a common modeling in- frastructure. IAMs are the primary tool for describing the human–Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species, land use and land cover change, and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. The iESM project integrates the economic and human dimension modeling of an IAM and a fully coupled ESM within a sin- gle simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore- omitted feedbacks between natural and societal drivers, we can improve scientific under- standing of the human–Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper de- scribes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.
An Evolutionary Game Theory Model of Spontaneous Brain Functioning.
Madeo, Dario; Talarico, Agostino; Pascual-Leone, Alvaro; Mocenni, Chiara; Santarnecchi, Emiliano
2017-11-22
Our brain is a complex system of interconnected regions spontaneously organized into distinct networks. The integration of information between and within these networks is a continuous process that can be observed even when the brain is at rest, i.e. not engaged in any particular task. Moreover, such spontaneous dynamics show predictive value over individual cognitive profile and constitute a potential marker in neurological and psychiatric conditions, making its understanding of fundamental importance in modern neuroscience. Here we present a theoretical and mathematical model based on an extension of evolutionary game theory on networks (EGN), able to capture brain's interregional dynamics by balancing emulative and non-emulative attitudes among brain regions. This results in the net behavior of nodes composing resting-state networks identified using functional magnetic resonance imaging (fMRI), determining their moment-to-moment level of activation and inhibition as expressed by positive and negative shifts in BOLD fMRI signal. By spontaneously generating low-frequency oscillatory behaviors, the EGN model is able to mimic functional connectivity dynamics, approximate fMRI time series on the basis of initial subset of available data, as well as simulate the impact of network lesions and provide evidence of compensation mechanisms across networks. Results suggest evolutionary game theory on networks as a new potential framework for the understanding of human brain network dynamics.
Modeling Marine Electromagnetic Survey with Radial Basis Function Networks
Directory of Open Access Journals (Sweden)
Agus Arif
2011-08-01
Full Text Available A marine electromagnetic survey is an engineering endeavour to discover the location and dimension of a hydrocarbon layer under an ocean floor. In this kind of survey, an array of electric and magnetic receivers are located on the sea floor and record the scattered, refracted and reflected electromagnetic wave, which has been transmitted by an electric dipole antenna towed by a vessel. The data recorded in receivers must be processed and further analysed to estimate the hydrocarbon location and dimension. To conduct those analyses successfuly, a radial basis function (RBF network could be employed to become a forward model of the input-output relationship of the data from a marine electromagnetic survey. This type of neural networks is working based on distances between its inputs and predetermined centres of some basis functions. A previous research had been conducted to model the same marine electromagnetic survey using another type of neural networks, which is a multi layer perceptron (MLP network. By comparing their validation and training performances (mean-squared errors and correlation coefficients, it is concluded that, in this case, the MLP network is comparatively better than the RBF network
Longitudinal functional principal component modelling via Stochastic Approximation Monte Carlo
Martinez, Josue G.
2010-06-01
The authors consider the analysis of hierarchical longitudinal functional data based upon a functional principal components approach. In contrast to standard frequentist approaches to selecting the number of principal components, the authors do model averaging using a Bayesian formulation. A relatively straightforward reversible jump Markov Chain Monte Carlo formulation has poor mixing properties and in simulated data often becomes trapped at the wrong number of principal components. In order to overcome this, the authors show how to apply Stochastic Approximation Monte Carlo (SAMC) to this problem, a method that has the potential to explore the entire space and does not become trapped in local extrema. The combination of reversible jump methods and SAMC in hierarchical longitudinal functional data is simplified by a polar coordinate representation of the principal components. The approach is easy to implement and does well in simulated data in determining the distribution of the number of principal components, and in terms of its frequentist estimation properties. Empirical applications are also presented.
Minimal models on Riemann surfaces: The partition functions
International Nuclear Information System (INIS)
Foda, O.
1990-01-01
The Coulomb gas representation of the A n series of c=1-6/[m(m+1)], m≥3, minimal models is extended to compact Riemann surfaces of genus g>1. An integral representation of the partition functions, for any m and g is obtained as the difference of two gaussian correlation functions of a background charge, (background charge on sphere) x (1-g), and screening charges integrated over the surface. The coupling constant x (compacitification radius) 2 of the gaussian expressions are, as on the torus, m(m+1), and m/(m+1). The partition functions obtained are modular invariant, have the correct conformal anomaly and - restricting the propagation of states to a single handle - one can verify explicitly the decoupling of the null states. On the other hand, they are given in terms of coupled surface integrals, and it remains to show how they degenerate consistently to those on lower-genus surfaces. In this work, this is clear only at the lattice level, where no screening charges appear. (orig.)
Minimal models on Riemann surfaces: The partition functions
Energy Technology Data Exchange (ETDEWEB)
Foda, O. (Katholieke Univ. Nijmegen (Netherlands). Inst. voor Theoretische Fysica)
1990-06-04
The Coulomb gas representation of the A{sub n} series of c=1-6/(m(m+1)), m{ge}3, minimal models is extended to compact Riemann surfaces of genus g>1. An integral representation of the partition functions, for any m and g is obtained as the difference of two gaussian correlation functions of a background charge, (background charge on sphere) x (1-g), and screening charges integrated over the surface. The coupling constant x (compacitification radius){sup 2} of the gaussian expressions are, as on the torus, m(m+1), and m/(m+1). The partition functions obtained are modular invariant, have the correct conformal anomaly and - restricting the propagation of states to a single handle - one can verify explicitly the decoupling of the null states. On the other hand, they are given in terms of coupled surface integrals, and it remains to show how they degenerate consistently to those on lower-genus surfaces. In this work, this is clear only at the lattice level, where no screening charges appear. (orig.).
Directory of Open Access Journals (Sweden)
Nick Scott
Full Text Available To determine the effects of 1 a condom distribution program and 2 a condom distribution program combined with opt-out sexually transmitted infection (STI screening on the transmission and prevalence of STIs in a prison system.Using data from an implementation evaluation of a state-wide prison condom program and parameter estimates from available literature, a deterministic model was developed to quantify the incidence and prevalence of sexually transmitted HIV, hepatitis B, chlamydia, syphilis and gonorrhoea across 14 Victorian prisons. The model included individual prison populations (by longer (>2 years or shorter sentence lengths and monthly prisoner transfers. For each STI, simulations were compared: without any intervention; with a condom distribution program; and with a combined condom and opt-out STI screening at prison reception intervention program.Condoms reduced the annual incidence of syphilis by 99% (N = 66 averted cases; gonorrhoea by 98% (N = 113 cases; hepatitis B by 71% (N = 5 cases; chlamydia by 27% (N = 196 cases; and HIV by 50% (N = 2 cases every 10 years. Condom availability changed the in-prison epidemiology of gonorrhoea and syphilis from self-sustaining to levels unlikely to result in infection outbreaks; however, condoms did not reduce chlamydia prevalence below a self-sustaining level due to its high infectiousness, high prevalence and low detection rate. When combined with a screening intervention program, condoms reduced chlamydia prevalence further, but not below a self-sustaining level. The low prevalence of HIV and hepatitis B in Australian prisons meant the effects of condoms were predicted to be small.Condoms are predicted to effectively reduce the incidence of STIs in prison and are predicted to control syphilis and gonorrhoea transmission, however even combined with a screening on arrival program may be insufficient to reduce chlamydia prevalence below self-sustaining levels. To control chlamydia transmission
Scott, Nick; McBryde, Emma; Kirwan, Amy; Stoové, Mark
2015-01-01
To determine the effects of 1) a condom distribution program and 2) a condom distribution program combined with opt-out sexually transmitted infection (STI) screening on the transmission and prevalence of STIs in a prison system. Using data from an implementation evaluation of a state-wide prison condom program and parameter estimates from available literature, a deterministic model was developed to quantify the incidence and prevalence of sexually transmitted HIV, hepatitis B, chlamydia, syphilis and gonorrhoea across 14 Victorian prisons. The model included individual prison populations (by longer (>2 years) or shorter sentence lengths) and monthly prisoner transfers. For each STI, simulations were compared: without any intervention; with a condom distribution program; and with a combined condom and opt-out STI screening at prison reception intervention program. Condoms reduced the annual incidence of syphilis by 99% (N = 66 averted cases); gonorrhoea by 98% (N = 113 cases); hepatitis B by 71% (N = 5 cases); chlamydia by 27% (N = 196 cases); and HIV by 50% (N = 2 cases every 10 years). Condom availability changed the in-prison epidemiology of gonorrhoea and syphilis from self-sustaining to levels unlikely to result in infection outbreaks; however, condoms did not reduce chlamydia prevalence below a self-sustaining level due to its high infectiousness, high prevalence and low detection rate. When combined with a screening intervention program, condoms reduced chlamydia prevalence further, but not below a self-sustaining level. The low prevalence of HIV and hepatitis B in Australian prisons meant the effects of condoms were predicted to be small. Condoms are predicted to effectively reduce the incidence of STIs in prison and are predicted to control syphilis and gonorrhoea transmission, however even combined with a screening on arrival program may be insufficient to reduce chlamydia prevalence below self-sustaining levels. To control chlamydia transmission
Decruyenaere, Alexander; Decruyenaere, Philippe; Peeters, Patrick; Vermassen, Frank
2015-09-15
BACKGROUND Kidney transplantation is the preferred treatment for patients with end-stage renal disease. Delayed graft function (DGF) is a common complication and is associated with short- and long-term outcomes. Several predictive models for DGF have been developed. MATERIAL AND METHODS 497 kidney transplantations from deceased donors at our center between 2005-2011 are included. Firstly, the predictive accuracy of the existing models proposed by Irish et al. (M1), Jeldres et al. (M2), Chapal et al. (M3), and Zaza et al. (M4) was assessed. Secondly, the existing models were aggregated into a meta-model (MM) using stacked regressions. Finally, the association between 47 risk factors and DGF was studied in our -cohort-fitted model (CFM) using logistic regression. The accuracy of all models was assessed by area under the receiver operating characteristic curve (AUROC) and Hosmer-Lemeshow test. RESULTS M1, M2, M3, M4, MM, and CFM have AUROCs of 0.78, 0.65, 0.59, 0.67, 0.78, and 0.82, respectively. M1 (P=0.018), M2 (Ppredictive models for DGF overestimate the risk in a cohort with a low incidence of DGF. We have identified 2 recipient parameters that are not included in previous models: cardiac function and preoperative diastolic blood pressure.
Constipation and Incident CKD.
Sumida, Keiichi; Molnar, Miklos Z; Potukuchi, Praveen K; Thomas, Fridtjof; Lu, Jun Ling; Matsushita, Kunihiro; Yamagata, Kunihiro; Kalantar-Zadeh, Kamyar; Kovesdy, Csaba P
2017-04-01
Constipation is one of the most prevalent conditions in primary care settings and increases the risk of cardiovascular disease, potentially through processes mediated by altered gut microbiota. However, little is known about the association of constipation with CKD. In a nationwide cohort of 3,504,732 United States veterans with an eGFR ≥60 ml/min per 1.73 m 2 , we examined the association of constipation status and severity (absent, mild, or moderate/severe), defined using diagnostic codes and laxative use, with incident CKD, incident ESRD, and change in eGFR in Cox models (for time-to-event analyses) and multinomial logistic regression models (for change in eGFR). Among patients, the mean (SD) age was 60.0 (14.1) years old; 93.2% of patients were men, and 24.7% were diabetic. After multivariable adjustments, compared with patients without constipation, patients with constipation had higher incidence rates of CKD (hazard ratio, 1.13; 95% confidence interval [95% CI], 1.11 to 1.14) and ESRD (hazard ratio, 1.09; 95% CI, 1.01 to 1.18) and faster eGFR decline (multinomial odds ratios for eGFR slope constipation associated with an incrementally higher risk for each renal outcome. In conclusion, constipation status and severity associate with higher risk of incident CKD and ESRD and with progressive eGFR decline, independent of known risk factors. Further studies should elucidate the underlying mechanisms. Copyright © 2017 by the American Society of Nephrology.
Nilsson, Heléne; Rüter, Anders
2008-06-01
Organizations involved in disaster response often have a defined operative level of management (command and control) that can take the overall decisions regarding the mobilization and distribution of resources and distribution of casualties. This level of management can be referred to as strategic management. The aim of this pilot study was to show the possibility, in simulation exercises, to relate decisions made regarding resources to patient outcome. The simulation system used measures to determine if lifesaving interventions are performed in time or not in relation to patient outcome. Evaluation was made with sets of performance indicators