899 resultados para diffusion process, wavelet estimator, non-parametric rate of convergence, Markov chain, estimation of unknown signal


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The effect of water potential ( J w ) on the growth of 15 fungal species isolated from cheeses was analysed. The species, identified mainly by analysis of DNA sequences, belonged to genera Penicillium , Geotrichum , Mucor , Aspergillus , Microascus and Talaromyces . Particularly, the effect of matric potential ( J m ), and ionic (NaCl) and non-ionic (glycerol) solute potentials ( J s ) on growth rate was studied. The response of strains was highly dependent on the type of J w . For J s , clear profiles for optimal, permissive and marginal conditions for growth were obtained, and differences in growth rate were achieved comparing NaCl and glycerol for most of the species. Conversely, a sustained growth was obtained for J m in all the strains, with the exception of Aspergillus pseudoglaucus , whose growth increased proportionally to the level of water stress. Our results might help to understand the impact of environmental factors on the ecophysiology and dynamics of fungal populations associated to cheeses.

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Along the recent years, several moving object detection strategies by non-parametric background-foreground modeling have been proposed. To combine both models and to obtain the probability of a pixel to belong to the foreground, these strategies make use of Bayesian classifiers. However, these classifiers do not allow to take advantage of additional prior information at different pixels. So, we propose a novel and efficient alternative Bayesian classifier that is suitable for this kind of strategies and that allows the use of whatever prior information. Additionally, we present an effective method to dynamically estimate prior probability from the result of a particle filter-based tracking strategy.

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The dynamic behaviour of a fishing vessel in waves is studied in order to reveal its parametric rolling characteristics. This paper presents experimental and numerical results in longitudinal regular waves. The experimental results are compared against the results of a time-domain non-linear strip theory model of ship motions in six degrees-of-freedom. These results contribute to the validation of the parametric rolling prediction method, so that it can be used as an assessment tool to evaluate both the susceptibility and severity of occurrence of parametric rolling at the early design stage of these types of vessels.

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The effect of water potential ( J w ) on the growth of 15 fungal species isolated from cheeses was analysed. The species, identi fi ed mainly by analysis of DNA sequences, belonged to genera Penicillium, Geotrichum, Mucor , Aspergillus , Microascus and Talaromyces . Particularly, the effect of matric potential ( J m ), and ionic (NaCl) and non-ionic (glycerol) solute potentials ( J s ) on growth rate was studied. The response of strains was highly dependent on the type of J w . For J s, clear profiles for optimal, permissive and marginal conditions for growth were obtained, and differences in growth rate were achieved comparing NaCl and glycerol for most of the species. Conversely, a sustained growth was obtained for J m in all the strains, with the exception of Aspergillus pseudoglaucus, whose growth increased proportionally to the level of water stress. Our results might help to understand the impact of environmental factors on the ecophysiology and dynamics of fungal populations associated to cheeses.

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This work presents the evaluation of a new non-contact technique to assess the fatigue damage state of CFRP structures by measuring surface roughness parameters. Surface roughness and stiffness degradation have been measured in CFRP coupons cycled with constant amplitude loads, and a Pearson?s correlation of 0.79 was obtained between both variables. Results suggest that changes on the surface roughness measured in strategic zones of components made of the evaluated CFRP, could be indicative of the level of damage due to fatigue loads. This methodology could be useful for other FRP due to similarities in the fatigue damage process.

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In this article, a model for the determination of displacements, deformations and tensions of a submarine pipeline during the construction is presented. The process is carried out from an initial floating situation to the final laying position on the seabed. The existence of currents and small waves are also considered. Firstly, this technique, usually applied to polyethylene pipelines, is described in this paper as well as some real world examples, as well as the variables that can be modified to control the behavior of the structure. A detailed description of the actions in this process is considered, specially the ones related to marine environment, as Archimedes force, current and sea waves. The behavior of the pipeline is modeled with a non linear elasto dynamic model where geometric non linearities are taken into account. A 3-D beam model, without cross section deformation effects, is developed. Special care is taken in the numerical analysis, developed within an updated lagrangian formulation framework, with the sea bed contact, the follower forces due to the external water pressures and the dynamic actions. Finally, some subroutines are implemented into ANSYS to simulate the two dimensional case, where the whole construction process is achieved. With this software, a sensibility analysis of the bending moments, axial forces and stresses obtained with different values of the control variables in order to optimize the construction steps. These control variables are, the axial load in the pipe, the inundated inner length and the distance of the control barge from the coast.

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The question was addressed whether the risk of cancer of an individual in a heterogeneous population can be predicted on the basis of measurable biochemical and biological variables postulated to be associated with the process of chemical carcinogenesis. Using the skin tumor model with outbred male NMRI mice, the latency time for the appearance of a papilloma was used as an indicator of the individual cancer risk. Starting at 8 weeks of age, a group of 29 mice was treated twice weekly with 20 nmol of 7,12-dimethylbenz[alpha]anthracene (DMBA) applied to back skin. The individual papilloma latency time ranged from 13.5 to 25 weeks of treatment. Two weeks after the appearance of the first papilloma in each mouse, an osmotic minipump delivering 5-bromo-2'-deoxyuridine was s.c. implanted and the mouse was killed 24 hr later. Levels of DMBA-DNA adducts, of 8-hydroxy-2'-deoxyguanosine, and various measures of the kinetics of cell division were determined in the epidermis of the treated skin area. The levels of 8-hydroxy-2'-deoxyguanosine and the fraction of cells in DNA replication (labeling index for the incorporation of 5-bromo-2'-deoxyuridine) were significantly higher in those mice that showed short latency times. On the other hand, the levels of DMBA-DNA adducts were lowest in animals with short latency times. The latter finding was rather unexpected but can be explained as a consequence of the inverse correlation seen for the labeling index: with each round of cell division, the adduct concentration is reduced to 50% because the new DNA strand is free of DMBA adducts until the next treatment. Under the conditions of this bioassay, therefore, oxygen radical-related genotoxicity and the rate of cell division, rather than levels of carcinogen-DNA adducts, were found to be of predictive value as indicators of an individual cancer risk.

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The aim of this thesis was to validate the use of infrared thermography (IRT) to non-invasively measure emotional reactions to different situations in pet dogs (Canis familiaris). A preliminary test, aimed to evaluate the correlation between eye-temperature and rectal temperature in dog, was performed. Then, in three different situations, negative (veterinary visit), positive (palatable food rewards), and mildly stressing followed by mildly positive (separation from and reunion with the owner), variations in heat emitted from lacrimal caruncle (referred to as eye temperature) were measured with an infrared thermographic camera. In addition, heart rate and heart rate variability parameters were collected using a non-invasive heart rate monitor designed for human use and validated on dogs. All experiments were video recorded to allow behavioral coding. During the negative situation dogs’ level of activity and stress related behaviors varied across compared to the baseline and dogs showed an increase in eye temperature despite having a significant decrease in the level of activity. The positive situation was characterized by a peak in eye temperature and mean HR and dogs engaged in behaviors indicating a positive arousal, focusing on food treats and tail wagging but there were not variations in HRV during stimulation but only an increment in SDNN immediately after the stimulus. In the separation from and reunion with the owner dogs’ eye temperature and mean HR did not vary neither in the stressful nor in the positive situations, RMSSD increased after the positive episode, SDNN dropped during the two stimulations and it increased after the stimulations. During the separation from the owner dogs were mainly directed to the door or to the experimenter while during the reunion with the owner dogs were focused mainly on the owner and on the environment, exhibiting safe base effect. A different approach was used to assess the welfare of shelter dogs. Dogs were implanted with a telemeter and after implantation dogs were housed in sequence in four different situations lasting 1 week: alone, alone with toys and a stretch cot for sleeping, with an unknown, spayed, female, and alone with a daily 2-hours interaction with an experimenter. Two different approaches were tried: partially random extracted fragments from every week, behaviors from 8 a.m. to 4 p.m. were continuous during baseline and the female situation. Results showed different reactions by dogs to the different situations and interestingly not all enrichments were enjoyed by the dogs improving their welfare. Overall results suggest that IRT may represent a useful tool to investigate emotional reactions in dogs. Nevertheless, further research is needed to establish the specificity and sensivity of IRT in this context and to assess how different dogs’ characteristics, breed, previous experience and the valence and arousal elicited by the stimulus could influence the magnitude and type of the response. The role of HRV in understanding emotional valence and the one of telemeters in understanding long-term effects on sheltered dogs’ welfare is also discussed.

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Introduction. The idea that “merit” should be the guiding principle of judicial selections is a universal principle, unlikely to be contested in whatever legal system. What differs considerably across legal cultures, however, is the way in which “merit” is defined. For deeper cultural and historical reasons, the current definition of “merit” in the process of judicial selections in the Czech Republic, at least in the way it is implemented in the institutional settings, is an odd mongrel. The old technocratic Austrian judicial heritage has in some aspects merged with, in others was altered or destroyed, by the Communist past. After 1989, some aspects of the judicial organisation were amended, with the most problematic elements removed. Furthermore, several old as well as new provisions relating to the judiciary were struck down by the Constitutional Court. However, apart from these rather haphazard interventions, there has been neither a sustained discussion as to how a new judicial architecture and system of judicial appointments ought to look like nor much of broader, conceptual reform in this regard. Thus, some twenty five years after the Velvet Revolution of 1989, the guiding principles for judicial selection and appointments are still a debate to be had.

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Ballooning is a form of aerial movement practiced by most miniature and some adult spiders. Very few studies have investigated the composition and rate of spider ballooning in Australian agroecosystems. Water traps were used to compare ballooning rates in irrigated soybean crops and nearby non-crop areas in southeast Queensland over two summer seasons. The highest ballooning rate (14.8 spiders/m(2) per day) was recorded in a soybean field, non-crop areas (7.0 spiders/m(2) per day) and a dry land mungbean field (6.8 spiders/m(2) per day) having similar rates. Spider ballooning in soybean increased throughout the season and showed three peaks and intervening troughs. A similar pattern in ballooning peaks was observed in non-crop areas however the numbers were lower. Peaks in ballooning activity where synchronised across habitat types and some spider groups. Composition of the ballooning fauna was different from that of the ground-dwelling fauna, some families being present in both. Ballooning is an important behaviour in terms of population dynamics for a number of spider groups in soybean and the implications for pest control are discussed. (C) 2004 Elsevier BN. All rights reserved.

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Samples from New Zealand and Australia have been tested in an adiabatic oven to assess the effect of rank on the R-70 selfheating rate of coal. A non-linear relationship can be defined for coals from both countries using the revised Suggate rank (S-r) parameter. Subbituminous coals have the highest R-70 self-heating rate values, which are 20 times that of high volatile A bituminous coals on a dry mineral matter free basis (similar to 1 cf. 20 degrees C h(-1)). However, the moderating effects of moisture and mineral matter can reduce this difference to only 2-3 times for coal in-situ. (c) 2005 Elsevier B.V All rights reserved.

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Rates of food intake in animals consuming abundant prey can be constrained by the rates of digestion or excretion of ingested substances, such as salt, particularly so in the animals that regularly migrate between freshwater and saltwater environments. We tested this hypothesis in a long-distance migrant shorebird, the eastern curlew Numenius madagascariensis (suborder Charadrii), foraging on intertidal decapods in eastern Australia. We predicted that if food intake rates are constrained osmotically, individuals with access to freshwater and less saline prey (FW group) would have higher rates of food and water intake than individuals with seawater-only access (SW group). Food intake rates did not differ between the FW and SW groups (0.14 g ash-free dry mass min(-1)), nor did the water influx rates (0.75 g min(-1)). Salt intake rates were lower at FW sites (19.3 versus 23.3 mg NaCl min(-1)) and overall they were similar to those of marine birds. Food intake rate in the eastern curlew appeared limited by digestive rather than by osmoregulatory capacity.

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The aim of this work was to demonstrate at pilot scale a high level of energy recovery from sewage utilising a primary Anaerobic Migrating Bed Reactor (AMBR) operating at ambient temperature to convert COD to methane. The focus is the reduction in non-renewable CO2 emissions resulting from reduced energy requirements for sewage treatment. A pilot AMBR was operated on screened sewage over the period June 2003 to September 2004. The study was divided into two experimental phases. In Phase 1 the process operated at a feed rate of 10 L/h (HRT 50 h), SRT 63 days, average temperature 28 degrees C and mixing time fraction 0.05. In Phase 2 the operating parameters were 20 L/h, 26 days, 16 degrees C and 0.025. Methane production was 66% of total sewage COD in Phase 1 and 23% in Phase 2. Gas mixing of the reactor provided micro-aeration which suppressed sulphide production. Intermittent gas mixing at a useful power input of 6 W/m(3) provided satisfactory process performance in both phases. Energy consumption for mixing was about 1.5% of the energy conversion to methane in both operating phases. Comparative analysis with previously published data confirmed that methane supersaturation resulted in significant losses of methane in the effluent of anaerobic treatment systems. No cases have been reported where methane was considered to be supersaturated in the effluent. We have shown that methane supersaturation is likely to be significant and that methane losses in the effluent are likely to have been greater than previously predicted. Dissolved methane concentrations were measured at up to 2.2 times the saturation concentration relative to the mixing gas composition. However, this study has also demonstrated that despite methane supersaturation occurring, microaeration can result in significantly lower losses of methane in the effluent (< 11% in this study), and has demonstrated that anaerobic sewage treatment can genuinely provide energy recovery. The goal of demonstrating a high level of energy recovery in an ambient anaerobic bioreactor was achieved. An AMBR operating at ambient temperature can achieve up to 70% conversion of sewage COD to methane, depending on SRT and temperature. (c) 2006 Wiley Periodicals, Inc.

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Are the learning procedures of genetic algorithms (GAs) able to generate optimal architectures for artificial neural networks (ANNs) in high frequency data? In this experimental study,GAs are used to identify the best architecture for ANNs. Additional learning is undertaken by the ANNs to forecast daily excess stock returns. No ANN architectures were able to outperform a random walk,despite the finding of non-linearity in the excess returns. This failure is attributed to the absence of suitable ANN structures and further implies that researchers need to be cautious when making inferences from ANN results that use high frequency data.