784 research outputs found
Composition of Stochastic Transition Systems Based on Spans and Couplings
Conventional approaches for parallel composition of stochastic systems relate probability measures of the individual components in terms of product measures. Such approaches rely on the assumption that components interact stochastically independent, which might be too rigid for modeling real world systems. In this paper, we introduce a parallel-composition operator for stochastic transition systems that is based on couplings of probability measures and does not impose any stochastic assumptions. When composing systems within our framework, the intended dependencies between components can be determined by providing so-called spans and span couplings. We present a congruence result for our operator with respect to a standard notion of bisimilarity and develop a general theory for spans, exploiting deep results from descriptive set theory. As an application of our general approach, we propose a model for stochastic hybrid systems called stochastic hybrid motion automata
Subnational nutrient budgets to monitor environmental risks in EU agriculture: calculating phosphorus budgets for 243 EU28 regions using public data
This paper presents a method to estimate soil surface phosphorus (P) budgets for 243 subnational regions in EU28. This is about the maximum spatial resolution that can be achieved mainly using international datasets that are regularly updated. Similar subnational budgets could be established for nitrogen (N) with some additions to this method. Increasing the spatial resolution from national to subnational is one way to address the well-known issue that national nutrient budgets sometimes mask considerable heterogeneity, i.e., regional surpluses and deficits that are not seen in national averages. Our results indeed show how a rich structure of different P budgets emerges when moving from national to subnational level. Another approach is to exclude the most extensively managed areas from the budgets, to better represent the surplus in intensive agriculture areas. Here, we show that both approaches are useful and sometimes important as they can affect P surplus estimates by about 10\ua0kg\ua0P\ua0ha− 1\ua0y− 1\ua0or more. The choice of spatial resolution is a trade-off between accuracy and precision. National budgets are the most accurate thanks to good data coverage, but they sometimes fail to identify considerable P surpluses and deficits at subnational level. Increasing the precision (spatial resolution) gradually reveals this heterogeneity but comes at the cost of growing data gaps, which we discuss in detail. These subnational P surpluses represent a middle ground which may prove useful as one indicator among others to monitor the development of environmental risks and resource problems over time
The acute phase protein, haptoglobin : a potential parameter in welfare assessment?
Physiological parameters are important measures in animal welfare assessment. To assess the amount of stress an animal experiences, stress hormones like cortisol are frequently used. However, measuring cortisol has major disadvantages due to its rapid reactivity and decline and many influencing factors. Other potential alternative markers are acute phase proteins, since stress is known to affect the immune system. A pilot study was conducted to investigate the response of the acute phase protein, plasma haptoglobine (HP), in pigs subjected to a stressor (food deprivation) and to examine the correlation between HP levels and average daily growth (ADG). Forty grower pigs (25.1 ± 4.4 kg, mean ± SD) (sex and former pen mates balanced), were allocated to 4 conventional pens, 2 treatment (T) and 2 control (C) groups (10 pigs per pen). After 10 days of adaptation the experiment started and ran for 3 weeks. In the 2nd week, T groups were repeatedly subjected to an 8-hour food deprivation (day 1, 3, 5 and 7 of week 2), C groups had normal, unrestricted, access to food. Pigs were weighed twice a week and blood was collected once a week (every 5th day). Mean levels of plasma HP of C and T groups showed large variation between individuals (C groups, week 2: 1.84 ± 3.11 mg/ml; T groups, week 2: 1.40 ± 1.16 mg/ml). No significant differences (Kruskal-Wallis test) in HP levels or growth were found between the C and T groups or between the different weeks within the T groups. Significant negative weak to moderate correlations were found between ADG and HP levels (HP week 1 and ADG week 1: rs = -0.47, p=0.005; HP week 2 and ADG total; rs= -0.60, p=0.015; HP week 3 and ADG total: rs = -0.43, p=0.025; average HP total and ADG total: rs= -0.41, p=0.017). Large variations in HP levels between individuals were shown and no effect of treatment on HP levels or growth was found. Possibly, food deprivation had no apparent stress eliciting effect. Despite these results, interesting correlations between the level of HP and ADG were found, corroborating the inverse relationship between the acute phase response and growth. To further investigate the relation of the acute phase response and stress a successive experiment will be conducted in which we apply a stronger stressor (mixing pigs) and combine the physiological data with behavior
AUTOMATIC DETECTION OF PLANTED TREES AND THEIR HEIGHTS USING PHOTOGRAMMETRIC RPA POINT CLOUDS
This work aims to analyze the potential of the Photogrammetric Point Cloud (PPC) obtained from Remote Piloted Aircraft (RPA) optical images for detecting and obtaining tree heights in a loblolly pine plantation using a global maximum filter. The enhanced algorithm used in this study is then named STD (Single Tree Detection). Field surveys were conducted to count all the trees in the field (Forest Census) and measure the trees’ height with a vertex hypsometer. The results were faced to PCC outcomes. The detection rate (r) was equal to the precision rate (p), indicating that the algorithm reaches a high tree detection performance. In summary, the STD algorithm segmented 2,192 trees, representing 89% of trees recorded in the forest census. The retrieved tree height reached, on average, a height of 17.05 m, whereas slightly higher by the traditional forest inventory (17.42 m). The root-mean-square error (RMSE) and Bias were 47 cm (2.8%) and -37 cm (-2.2%), respectively. The Dunnett test showed that the tree height did not significantly differ between the results obtained by traditional forest inventory from those generated by the STD. It confirms the potential use of PPC for forest inventory procedures
Alternative splicing is frequent during early embryonic development in mouse
<p>Abstract</p> <p>Background</p> <p>Alternative splicing is known to increase the complexity of mammalian transcriptomes since nearly all mammalian genes express multiple pre-mRNA isoforms. However, our knowledge of the extent and function of alternative splicing in early embryonic development is based mainly on a few isolated examples. High throughput technologies now allow us to study genome-wide alternative splicing during mouse development.</p> <p>Results</p> <p>A genome-wide analysis of alternative isoform expression in embryonic day 8.5, 9.5 and 11.5 mouse embryos and placenta was carried out using a splicing-sensitive exon microarray. We show that alternative splicing and isoform expression is frequent across developmental stages and tissues, and is comparable in frequency to the variation in whole-transcript expression. The genes that are alternatively spliced across our samples are disproportionately involved in important developmental processes. Finally, we find that a number of RNA binding proteins, including putative splicing factors, are differentially expressed and spliced across our samples suggesting that such proteins may be involved in regulating tissue and temporal variation in isoform expression. Using an example of a well characterized splicing factor, <it>Fox2</it>, we demonstrate that changes in <it>Fox2 </it>expression levels can be used to predict changes in inclusion levels of alternative exons that are flanked by Fox2 binding sites.</p> <p>Conclusions</p> <p>We propose that alternative splicing is an important developmental regulatory mechanism. We further propose that gene expression should routinely be monitored at both the whole transcript and the isoform level in developmental studies</p
Structural characterization of SiO2-Na2O-CaO-B2O3-MoO3 glasses
5 pagesNuclear spent fuel reprocessing generates high level radioactive waste with high Mo concentration that are currently immobilized in borosilicate glass matrices containing both alkali and alkaline-earth elements [1]. Because of its high field strength, Mo6+ ion has a limited solubility in silicate and borosilicate glasses and crystallization of alkali or alkaline-earth molybdates can be observed during melt cooling or heat treatment of glasses [2-4]. Glass composition changes can significantly modify the nature and the relative proportions of molybdate crystals that may form during natural cooling of the melt. For instance, in a previous work we showed that CaMoO4 crystallization tendency increased at the expenses of Na2MoO4 when B2O3 concentration increased in a SiO2-Na2O-CaO-MoO3 glass composition [4]. In this study, we present structural results on two series (Mx, By) of quenched glass samples belonging to this system using 29Si, 11B, 23Na MAS NMR and Raman spectroscopies. The effect of MoO3 on the glassy network structure is studied and its structural role is discussed (Mx series). The evolution of the distribution of Na+ ions within the borosilicate network is followed when B2O3 concentration increased (By series) and is discussed according to the evolution of the crystallization tendency of the melt. For all glasses, ESR was used to investigate the nature and the concentration of paramagnetic species
Cover crop grazing by sheep: successful partnerships between sheep and arable farmers (DiverIMPACTS Practice Abstract)
Based on the experience acquired by facilitating partnerships, a list of key and optional terms of agreements that support a successful partnership have been drawn up
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