Decision Support Systems for Weed Management

Editors: Guillermo R. Chantre, José L. González-Andújar.Weed management Decision Support Systems (DSS) are increasingly important computer-based tools for modern agriculture. Nowadays, extensive agriculture has become highly dependent on external inputs and both economic costs, as well the negative environmental impact of agricultural activities, demands knowledge-based technology for the optimization and protection of non-renewable resources. In this context, weed management strategies should aim to maximize economic profit by preserving and enhancing agricultural systems. Although previous contributions focusing on weed biology and weed management provide valuable insight on many aspects of weed species ecology and practical guides for weed control, no attempts have been made to highlight the forthcoming importance of DSS in weed management. This book is a first attempt to integrate 'concepts and practice' providing a novel guide to the state-of-art of DSS and the future prospects which hopefully would be of interest to higher-level students, academics and professionals in related areas

Effects of nutrient addition and soil drainage on germination of N-fixing and non-N-fixing tropical dry forest tree species

To develop generalised predictions regarding the effects of atmospheric nitrogen (N) and phosphorus (P) deposition on vegetation communities, it is necessary to account for the impacts of increased nutrient availability on the early life history stages of plants. Additionally, it is important to determine if these responses (a) differ between plant functional groups and (b) are modulated by soil drainage, which may affect the persistence of added nutrients. We experimentally assessed seed germination responses (germination proportion and germination energy, i.e. time to germination) of commonly occurring N-fixing and non-N-fixing tropical dry forest tree species found in India to simulated N and P deposition in well-drained soils, as well as soils with impeded drainage. When soils were not allowed to drain, germination proportion declined with nutrient addition, while germination energy remained unchanged. Stronger declines in germination proportion were observed for N-fixing species. In free-draining soils, nutrient addition did not affect germination proportion in either functional group. However, we detected a trend of delayed germination with nutrient addition, especially in N-fixers. Our results suggest that nutrient deposition can lead to potential shifts in functional dominance and tree community composition of tropical dry forests in the long term through its effects on early life stages of trees, although the mechanisms underlying the observed germination responses remain unclear. Further, such effects are likely to be spatially variable across the geographic range in which tropical dry forests occur depending on soil drainage properties

High-Throughput Analysis of Promoter Occupancy Reveals New Targets for Arx, a Gene Mutated in Mental Retardation and Interneuronopathies

Genetic investigations of X-linked intellectual disabilities have implicated the ARX (Aristaless-related homeobox) gene in a wide spectrum of disorders extending from phenotypes characterised by severe neuronal migration defects such as lissencephaly, to mild or moderate forms of mental retardation without apparent brain abnormalities but with associated features of dystonia and epilepsy. Analysis of Arx spatio-temporal localisation profile in mouse revealed expression in telencephalic structures, mainly restricted to populations of GABAergic neurons at all stages of development. Furthermore, studies of the effects of ARX loss of function in humans and animal models revealed varying defects, suggesting multiple roles of this gene during brain development. However, to date, little is known about how ARX functions as a transcription factor and the nature of its targets. To better understand its role, we combined chromatin immunoprecipitation and mRNA expression with microarray analysis and identified a total of 1006 gene promoters bound by Arx in transfected neuroblastoma (N2a) cells and in mouse embryonic brain. Approximately 24% of Arx-bound genes were found to show expression changes following Arx overexpression or knock-down. Several of the Arx target genes we identified are known to be important for a variety of functions in brain development and some of them suggest new functions for Arx. Overall, these results identified multiple new candidate targets for Arx and should help to better understand the pathophysiological mechanisms of intellectual disability and epilepsy associated with ARX mutations

Antibacterial Activities of Nisin Z Encapsulated in Liposomes or Produced In Situ by Mixed Culture during Cheddar Cheese Ripening

This study investigated both the activity of nisin Z, either encapsulated in liposomes or produced in situ by a mixed starter, against Listeria innocua, Lactococcus spp., and Lactobacillus casei subsp. casei and the distribution of nisin Z in a Cheddar cheese matrix. Nisin Z molecules were visualized using gold-labeled anti-nisin Z monoclonal antibodies and transmission electron microscopy (immune-TEM). Experimental Cheddar cheeses were made using a nisinogenic mixed starter culture, containing Lactococcus lactis subsp. lactis biovar diacetylactis UL 719 as the nisin producer and two nisin-tolerant lactococcal strains and L. casei subsp. casei as secondary flora, and ripened at 7°C for 6 months. In some trials, L. innocua was added to cheese milk at 10(5) to 10(6) CFU/ml. In 6-month-old cheeses, 90% of the initial activity of encapsulated nisin (280 ± 14 IU/g) was recovered, in contrast to only 12% for initial nisin activity produced in situ by the nisinogenic starter (300 ± 15 IU/g). During ripening, immune-TEM observations showed that encapsulated nisin was located mainly at the fat/casein interface and/or embedded in whey pockets while nisin produced by biovar diacetylactis UL 719 was uniformly distributed in the fresh cheese matrix but concentrated in the fat area as the cheeses aged. Cell membrane in lactococci appeared to be the main nisin target, while in L. casei subsp. casei and L. innocua, nisin was more commonly observed in the cytoplasm. Cell wall disruption and digestion and lysis vesicle formation were common observations among strains exposed to nisin. Immune-TEM observations suggest several modes of action for nisin Z, which may be genus and/or species specific and may include intracellular target-specific activity. It was concluded that nisin-containing liposomes can provide a powerful tool to improve nisin stability and availability in the cheese matrix

Reliability Assessment of 4GSP/s Interleaved SAR ADC

International audienceFor high performance applications like satellite receivers, Interleaved Successive-Approximation-Register (ISAR) Analog to Digital Converter (ADC) are widely used because they have good tradeoff between high performance sampling rate, effective resolution, power and small area in GHz range. Very few work is reported about the impact of aging induced degradation in SAR ADC. After presenting the design content, experimental results of aging at 40°C and 125°C are shown. Degradation of static and dynamic performance parameters will be illustrated. Then, the analysis of reliability for all the critical sub-blocks of the ADC is discussed, i.e. switches in capacitor array, comparator and latch. In conclusion, the sub-block which is mainly responsible for performance degradation is the latch

Modélisation de la décorporation du Pu/am par le dtpa

A new tool has been developed to optimize DTPA efficacy as concerns reduction of effective dose after 239Pu wound. For example, the simulations show, for moderately soluble compounds (type M), a 1/3 decrease of effective dose is obtained after repeated early treatment (24 i.v. for 4 months), whereas a decrease by a factor 5 can be reached if treatments continue for 5 years at 2 week interval. By contrast, for poorly soluble compounds (type S), negligible efficacy is observed after early treatments, and a 3 time decrease of dose is obtained for treatments performed at 2 week interval for 50 years. Some of the hypotheses retained for modelling DTPA decorporation are validated from new experimental data published recently, and structure of a new model which can be applied both to Pu and Am is reported, taking into account urinary and faecal excretion, structure being suitable for different doses of DTPA and using various galenic forms. © 2009 EDP Sciences.Un nouvel outil a été développé pour optimiser l’efficacité des traitements par le DTPA après blessure, sur la base d’une réduction de la dose efficace engagée. Les simulations montrent, notamment, que pour du 239Pu modérément soluble (type M), des traitements précoces (24 i.v.) étalées sur 4 mois permettent une réduction d’un tiers de la dose, alors que leur prolongement sur 5 ans, avec un intervalle de 2 semaines, peut diminuer la dose d’un facteur 5. En revanche, pour des composés peu solubles (type S), l’efficacité des traitements précoces est négligeable et un gain dosimétrique d’un facteur 3 n’est atteint que pour des traitements effectués 2 fois par mois durant 50 ans. Certaines des hypothèses retenues pour la modélisation ont été validées par les résultats d’expérimentations animales récemment publiés. Enfin, la structure d’un nouveau modèle applicable à la fois au Pu et à l’Am est rapportée, structure tenant compte de la décorporation urinaire et fécale de ces actinides et qui pourrait être adapté à différentes posologies et formes galéniques de DTPA