THE VANISHING DISCOUNT APPROACH FOR THE AVERAGE CONTINUOUS CONTROL OF PIECEWISE DETERMINISTIC MARKOV PROCESSES

This work is concerned with the existence of an optimal control strategy for the long-run average continuous control problem of piecewise-deterministic Markov processes (PDMPs). In Costa and Dufour (2008), sufficient conditions were derived to ensure the existence of an optimal control by using the vanishing discount approach. These conditions were mainly expressed in terms of the relative difference of the alpha-discount value functions. The main goal of this paper is to derive tractable conditions directly related to the primitive data of the PDMP to ensure the existence of an optimal control. The present work can be seen as a continuation of the results derived in Costa and Dufour (2008). Our main assumptions are written in terms of some integro-differential inequalities related to the so-called expected growth condition, and geometric convergence of the post-jump location kernel associated to the PDMP. An example based on the capacity expansion problem is presented, illustrating the possible applications of the results developed in the paper.

Providing Integrity and Authenticity in DICOM Images: A Novel Approach

The increasing adoption of information systems in healthcare has led to a scenario where patient information security is more and more being regarded as a critical issue. Allowing patient information to be in jeopardy may lead to irreparable damage, physically, morally, and socially to the patient, potentially shaking the credibility of the healthcare institution. Medical images play a crucial role in such context, given their importance in diagnosis, treatment, and research. Therefore, it is vital to take measures in order to prevent tampering and determine their provenance. This demands adoption of security mechanisms to assure information integrity and authenticity. There are a number of works done in this field, based on two major approaches: use of metadata and use of watermarking. However, there still are limitations for both approaches that must be properly addressed. This paper presents a new method using cryptographic means to improve trustworthiness of medical images, providing a stronger link between the image and the information on its integrity and authenticity, without compromising image quality to the end user. Use of Digital Imaging and Communications in Medicine structures is also an advantage for ease of development and deployment.

A Geometric Approach for Turbo Decoding of Reed-Solomon Codes in QAM Modulation Schemes

This work studies the turbo decoding of Reed-Solomon codes in QAM modulation schemes for additive white Gaussian noise channels (AWGN) by using a geometric approach. Considering the relations between the Galois field elements of the Reed-Solomon code and the symbols combined with their geometric dispositions in the QAM constellation, a turbo decoding algorithm, based on the work of Chase and Pyndiah, is developed. Simulation results show that the performance achieved is similar to the one obtained with the pragmatic approach with binary decomposition and analysis.

A calibration approach based on Takagi-Sugeno fuzzy inference system for digital electronic compasses

Recently, the development of industrial processes brought on the outbreak of technologically complex systems. This development generated the necessity of research relative to the mathematical techniques that have the capacity to deal with project complexities and validation. Fuzzy models have been receiving particular attention in the area of nonlinear systems identification and analysis due to it is capacity to approximate nonlinear behavior and deal with uncertainty. A fuzzy rule-based model suitable for the approximation of many systems and functions is the Takagi-Sugeno (TS) fuzzy model. IS fuzzy models are nonlinear systems described by a set of if then rules which gives local linear representations of an underlying system. Such models can approximate a wide class of nonlinear systems. In this paper a performance analysis of a system based on IS fuzzy inference system for the calibration of electronic compass devices is considered. The contribution of the evaluated IS fuzzy inference system is to reduce the error obtained in data acquisition from a digital electronic compass. For the reliable operation of the TS fuzzy inference system, adequate error measurements must be taken. The error noise must be filtered before the application of the IS fuzzy inference system. The proposed method demonstrated an effectiveness of 57% at reducing the total error based on considered tests. (C) 2011 Elsevier Ltd. All rights reserved.

A new approach to heart valve tissue engineering: mimicking the heart ventricle with a ventricular assist device in a novel bioreactor

The `biomimetic` approach to tissue engineering usually involves the use of a bioreactor mimicking physiological parameters whilst supplying nutrients to the developing tissue. Here we present a new heart valve bioreactor, having as its centrepiece a ventricular assist device (VAD), which exposes the cell-scaffold constructs to a wider array of mechanical forces. The pump of the VAD has two chambers: a blood and a pneumatic chamber, separated by an elastic membrane. Pulsatile air-pressure is generated by a piston-type actuator and delivered to the pneumatic chamber, ejecting the fluid in the blood chamber. Subsequently, applied vacuum to the pneumatic chamber causes the blood chamber to fill. A mechanical heart valve was placed in the VAD`s inflow position. The tissue engineered (TE) valve was placed in the outflow position. The VAD was coupled in series with a Windkessel compliance chamber, variable throttle and reservoir, connected by silicone tubings. The reservoir sat on an elevated platform, allowing adjustment of ventricular preload between 0 and 11 mmHg. To allow for sterile gaseous exchange between the circuit interior and exterior, a 0.2 mu m filter was placed at the reservoir. Pressure and flow were registered downstream of the TE valve. The circuit was filled with culture medium and fitted in a standard 5% CO(2) incubator set at 37 degrees C. Pressure and flow waveforms were similar to those obtained under physiological conditions for the pulmonary circulation. The `cardiomimetic` approach presented here represents a new perspective to conventional biomimetic approaches in TE, with potential advantages. Copyright (C) 2010 John Wiley & Sons, Ltd.

Probing the hormonal activity of fractionated molecular humic components in tomato auxin mutants

We progressively reduced the complexity of humic matter by a mild sequential removal of unbound or free components, weakly, and strongly bound molecules. The auxin-like response of residues from each step was tested using tomato (cv. Micro-Tom) seedlings expressing DR5 auxin synthetic promoter fused to the beta-glucuronidase (GUS) reporter gene and the low auxin-sensitivity diageotropica (dgt) mutant. Both exogenous auxin and humic matter promoted lateral root emergence in the control, but failed to induce lateral roots in the dgt mutant. When strongly bound components were removed from humic matter by breaking the ester and ether bonds, the humic residues lost their ability to induce the DR5

A frailty modeling approach for parental effects in animal breeding

Survival models involving frailties are commonly applied in studies where correlated event time data arise due to natural or artificial clustering. In this paper we present an application of such models in the animal breeding field. Specifically, a mixed survival model with a multivariate correlated frailty term is proposed for the analysis of data from over 3611 Brazilian Nellore cattle. The primary aim is to evaluate parental genetic effects on the trait length in days that their progeny need to gain a commercially specified standard weight gain. This trait is not measured directly but can be estimated from growth data. Results point to the importance of genetic effects and suggest that these models constitute a valuable data analysis tool for beef cattle breeding.

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 August 2010-30 September 2010

This article documents the addition of 229 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Acacia auriculiformis x Acacia mangium hybrid, Alabama argillacea, Anoplopoma fimbria, Aplochiton zebra, Brevicoryne brassicae, Bruguiera gymnorhiza, Bucorvus leadbeateri, Delphacodes detecta, Tumidagena minuta, Dictyostelium giganteum, Echinogammarus berilloni, Epimedium sagittatum, Fraxinus excelsior, Labeo chrysophekadion, Oncorhynchus clarki lewisi, Paratrechina longicornis, Phaeocystis antarctica, Pinus roxburghii and Potamilus capax. These loci were cross-tested on the following species: Acacia peregrinalis, Acacia crassicarpa, Bruguiera cylindrica, Delphacodes detecta, Tumidagena minuta, Dictyostelium macrocephalum, Dictyostelium discoideum, Dictyostelium purpureum, Dictyostelium mucoroides, Dictyostelium rosarium, Polysphondylium pallidum, Epimedium brevicornum, Epimedium koreanum, Epimedium pubescens, Epimedium wushanese and Fraxinus angustifolia.

Molecular detection and differentiation of Brazilian and African isolates of the entomopathogen Neozygites tanajoae (Entomophthorales: Neozygitaceae) with PCR using specific primers

Neozygites tanajoae is an entomopathogenic fungus which has been used for biocontrol of the cassava green mite (Mononychellus tanajoa, CGM) in Africa. Establishment and dispersal of Brazilian isolates which have been introduced into some African countries in recent years to improve CGM control was followed with specific PCR assays. Two primer pairs, NEOSSU_F/NEOSSU_R and 8DDC_F/8DDC_R, were used to differentiate isolates collected from several locations in Brazil and from three countries in Africa, Benin, Ghana and Tanzania. The first primer pair enabled the species-specific detection of Neozygites tanajoae, while the second differentiated the Brazilian isolates from those of other geographical origin. PCR assays were designed for detection of fungal DNA in the matrix of dead infested mites since N. tanajoae is difficult to isolate and culture on selective artificial media. Our results show that all isolates (Brazilian and African) that sporulated on mummified mites were amplified with the first primer pair confirming their Neozygites tanajoae identity. The second pair amplified DNA from all the Brazilian isolates, but did not amplify any DNA samples from the African isolates. None of the two primers showed amplification neither from any of the non-sporulating mite extracts nor from the dead uninfected mites used as negative controls. We confirmed that the two primer pairs tested are suitable for the detection and differential identification of N. tanajoae isolates from Brazil and Africa and that they are useful to monitor the establishment and spread of the Brazilian isolates of N. tanajoae introduced into Benin or into other African countries for improvement of CGM biocontrol.

Water Resources Assessment at Piracicaba, Capivari and Jundiai River Basins: A Dynamic Systems Approach

The Piracicaba, Capivari, and Jundiai River Basins (RB-PCJ) are mainly located in the State of So Paulo, Brazil. Using a dynamics systems simulation model (WRM-PCJ) to assess water resources sustainability, five 50-year simulations were run. WRM-PCJ was developed as a tool to aid decision and policy makers on the RB-PCJ Watershed Committee. The model has 254 variables. The model was calibrated and validated using available information from the 80s. Falkenmark Water Stress Index went from 1,403 m(3) person (-aEuro parts per thousand 1) year (-aEuro parts per thousand 1) in 2004 to 734 m(3) P (-aEuro parts per thousand 1) year (-aEuro parts per thousand 1) in 2054, and Xu Sustainability Index from 0.44 to 0.20. In 2004, the Keller River Basin Development Phase was Conservation, and by 2054 was Augmentation. The three criteria used to evaluate water resources showed that the watershed is at crucial water resources management turning point. The WRM-PCJ performed well, and it proved to be an excellent tool for decision and policy makers at RB-PCJ.

Macroscopic root water uptake distribution using a matric flux potential approach

Hydrological models featuring root water uptake usually do not include compensation mechanisms such that reductions in uptake from dry layers are compensated by an increase in uptake from wetter layers. We developed a physically based root water uptake model with an implicit compensation mechanism. Based on an expression for the matric flux potential (M) as a function of the distance to the root, and assuming a depth-independent value of M at the root surface, uptake per layer is shown to be a function of layer bulk M, root surface M, and a weighting factor that depends on root length density and root radius. Actual transpiration can be calculated from the sum of layer uptake rates. The proposed reduction function (PRF) was built into the SWAP model, and predictions were compared to those made with the Feddes reduction function (FRF). Simulation results were tested against data from Canada (continuous spring wheat [(Triticum aestivum L.]) and Germany (spring wheat, winter barley [Hordeum vulgare L.], sugarbeet [Beta vulgaris L.], winter wheat rotation). For the Canadian data, the root mean square error of prediction (RMSEP) for water content in the upper soil layers was very similar for FRF and PRF; for the deeper layers, RMSEP was smaller for PRF. For the German data, RMSEP was lower for PRF in the upper layers and was similar for both models in the deeper layers. In conclusion, but dependent on the properties of the data sets available for testing,the incorporation of the new reduction function into SWAP was successful, providing new capabilities for simulating compensated root water uptake without increasing the number of input parameters or degrading model performance.

Pricing farm-level agricultural insurance: a Bayesian approach

This paper applies Hierarchical Bayesian Models to price farm-level yield insurance contracts. This methodology considers the temporal effect, the spatial dependence and spatio-temporal models. One of the major advantages of this framework is that an estimate of the premium rate is obtained directly from the posterior distribution. These methods were applied to a farm-level data set of soybean in the State of the Parana (Brazil), for the period between 1994 and 2003. The model selection was based on a posterior predictive criterion. This study improves considerably the estimation of the fair premium rates considering the small number of observations.

Molecular Identification and Phylogenetic Analysis of a Group 16SrI-B Phytoplasma Associated with Sugarcane Yellow Leaf Syndrome in Brazil

Yellow leaf syndrome was a serious problem in the beginning of the 1990s in Brazil, when yield losses were estimated to be around 50%. The disease is currently endemic, but it is considered potentially important. Previous studies have revealed only the presence of a luteovirus associated with the disease in Brazil. We report that a phytoplasma of 16SrI-B is also associated with this disease. This is the first demonstration of the presence of a group 16SrI-B phytoplasma in association with sugarcane yellow leaf in Brazil.

Molecular and morphological markers for rapid distinction between 2 Colletotrichum species

Endophytic microorganisms reside asymptomatically within plants and are a source of new bioactive products for use in medicine, agriculture, and industry. Colletotrichum (teleomorph Glomerella) is a fungus widely cited in the literature as a producer of antimicrobial substances. Identification at the species level, however, has been a problem in this type of study. Several authors have reported the presence of endophytic fungi from the medicinal plant Maytenus ilicifolia (espinheira-santa) in Brazil that has antimicrobial activity against various pathogens. Therefore, Colletotrichum strains were isolated from M. ilicifolia and identified based on morphology, RAPD markers, sequence data of the internal transcribed spacer regions (ITS-1 and ITS-2), the 5.8S gene, and species-specific PCR. The analyses suggested the presence of 2 species, Colletotrichum gloeosporioides and Colletotrichum boninense. Two morphological markers were characterized to allow C. gloeosporioides and C. boninense to be distinguished quickly and accurately. The molecular diagnosis of C. boninense was confirmed by using Coll and ITS4 primers. This species of Colletotrichum is reported for the first time in M. ilicifolia.

Molecular evidence of phytoplasma associated with witches` broom on passion fruit in five Brazilian States

Phytoplasmas are cell wall-less prokaryotes and phloem-inhabitants associated with diseases that affect several crops. Passion fruit is a tropical plant species cultivated in various Brazilian regions. Diseases are among the factors that may cause damage to this crop, and witches` broom is a very important one. This disease, associated with a phytoplasma, has been reported only in Brazil, where it was described in Rio de Janeiro and Pernambuco States at the beginning of the 1980`s. In 2005-2006, symptomatic plants Suspected of phytoplasma infection were sampled in areas located in Sao Paulo, Parana, Rio de Janeiro, Sergipe and Bahia. Amplification of DNA fragments of 1.2kb from nested PCR primed by the pairs 16mF2/mR1 and 16F2n/R2 revealed the presence of phytoplasma in the tissue of plants from all sampled regions. Molecular detection of the agent allowed confirmation of the diagnosis based on the symptomatology; demonstrated the strong association between diseased plants and a phytoplasma, confirming previous investigations based on electron microscopy;, and revealed the present occurrence of the agent in the States of Bahia, Parana, Rio de Janeiro, Sergipe, and Sao Paulo.