116 research outputs found
AnĂĄlisis de la diversidad de los sistemas de producciĂłn agrĂcolas: un caso de estudio en el suroeste de Francia
The huge changes in agricultural activities, which may be amplified by the forthcoming Common Agriculture Policy reform, call the future of crop-livestock systems into question and hence the impact of these changes on landscapes and biodiversity. We analyzed relationships between agriculture, landscape and biodiversity in south-western France. The study area covered about 4000 ha and included four villages. We conducted a survey of 56 farms. Multivariate analysis (multiple factor analysis and cluster analysis) were used to analyze relationships between 25 variables and to build a typology. The type of farming (beef and/or dairy cattle, cash crops), size (area and workforce) and cultivation practices, among others, were revealed as differentiating factors of farms. Six farming types were identified (1) hillside mixed crop-livestock farms, (2) large âcorporateâ farms, (3) extensive cattle farms, (4) large intensive farms on the valley sides, (5) small multiple-job holdings, and (6) âhobbyâ farms. The diversity of farming systems revealed the variable impact of the main drivers of change affecting agricultural development, particularly the enlargement and modernization of farms along with the demography of agricultural holdings.Los enormes cambios experimentados en las actividades agrĂcolas en Europa, que podrĂan ser amplificados por la prĂłxima reforma de la polĂtica agrĂcola comĂșn de Europa, cuestionan el futuro de los sistemas agropecuarios y, por tanto, el impacto de estos cambios en el paisaje y en la biodiversidad. Para ello, se estudiaron las relaciones entre la agricultura, el paisaje y la biodiversidad en el suroeste de Francia (Cerros de Gascuña). El ĂĄrea de estudio cubre aproximadamente 4000 ha e incluye cuatro municipios. Los datos relacionados con las actividades agrĂcolas provienen de encuestas realizadas en 56 explotaciones. Para estudiar las relaciones entre 25 variables, se utilizaron anĂĄlisis multivariados (anĂĄlisis factorial mĂșltiple y anĂĄlisis de conglomerados) y se elaborĂł una tipologĂa. Los factores de diferenciaciĂłn identificados, entre otros, son: el tipo de producciĂłn (ganado de carne y/o lechero, cultivos herbĂĄceos), tamaño (superficie y mano de obra) y prĂĄcticas de cultivo. Se distinguieron seis tipos de explotaciones: (1) explotaciones de ladera que combinan agricultura y ganaderĂa, (2) grandes explotaciones corporativas, (3) explotaciones ganaderas extensivas, (4) grandes explotaciones intensivas en valles, (5) pequeñas fincas explotadas a tiempo parcial, y (6) explotaciones para ocio. La diversidad de los sistemas de producciĂłn revelĂł el impacto variable de las principales fuerzas de cambio que afectan al desarrollo de la agricultura, en particular a la ampliaciĂłn y modernizaciĂłn de las explotaciones, junto con la demografĂa de la poblaciĂłn agrĂcola
Modélisation de la distribution des connaissances et des attitudes dans le domaine de l'énergie : Une simulation informatique et une étude empirique
Vacuum laser acceleration of relativistic electrons using plasma mirror injectors
Accelerating particles to relativistic energies over very short distances using lasers has been a long standing goal in physics. Among the various schemes proposed for electrons, vacuum laser acceleration has attracted considerable interest and has been extensively studied theoretically because of its appealing simplicity: electrons interact with an intense laser field in vacuum and can be continuously accelerated, provided they remain at a given phase of the field until they escape the laser beam. But demonstrating this effect experimentally has proved extremely challenging, as it imposes stringent requirements on the conditions of injection of electrons in the laser field. Here, we solve this long-standing experimental problem for the first time by using a plasma mirror to inject electrons in an ultraintense laser field, and obtain clear evidence of vacuum laser acceleration. With the advent of PetaWatt class lasers, this scheme could provide a competitive source of very high charge (nC) and ultrashort relativistic electron beams
Bayesian optimization of laser-plasma accelerators assisted by reduced physical models
Particle-in-cell simulations are among the most essential tools for the
modeling and optimization of laser-plasma accelerators, since they reproduce
the physics from first principles. However, the high computational cost
associated with them can severely limit the scope of parameter and design
optimization studies. Here, we show that a multitask Bayesian optimization
algorithm can be used to mitigate the need for such high-fidelity simulations
by incorporating information from inexpensive evaluations of reduced physical
models. In a proof-of-principle study, where a high-fidelity optimization with
FBPIC is assisted by reduced-model simulations with Wake-T, the algorithm
demonstrates an order-of-magnitude speedup. This opens a path for the
cost-effective optimization of laser-plasma accelerators in large parameter
spaces, an important step towards fulfilling the high beam quality requirements
of future applications
Adaptive changes of human islets to an obesogenic environment in the mouse
Routing protocols in wireless sensor networks (WSN) face two main challenges: first, the challenging environments in which WSNs are deployed negatively affect the quality of the routing process. Therefore, routing protocols for WSNs should recognize and react to node failures and packet losses. Second, sensor nodes are battery-powered, which makes power a scarce resource. Routing protocols should optimize power consumption to prolong the lifetime of the WSN. In this paper, we present a new adaptive routing protocol for WSNs, we call it M^2RC. M^2RC has two phases: mesh establishment phase and data forwarding phase. In the first phase, M^2RC establishes the routing state to enable multipath data forwarding. In the second phase, M^2RC forwards data packets from the source to the sink. Targeting hop-by-hop reliability, an M^2RC forwarding node waits for an acknowledgement (ACK) that its packets were correctly received at the next neighbor. Based on this feedback, an M^2RC node applies multiplicative-increase/additive-decrease (MIAD) to control the number of neighbors targeted by its packet broadcast. We simulated M^2RC in the ns-2 simulator and compared it to GRAB, Max-power, and Min-power routing schemes. Our simulations show that M^2RC achieves the highest throughput with at least 10-30% less consumed power per delivered report in scenarios where a certain number of nodes unexpectedly fail.National Science Foundation (ITR ANI-0205294, EIA-0202067, ANI-0095988, ANI-9986397
Regulation of LRRK2 Expression Points to a Functional Role in Human Monocyte Maturation
Genetic variants of Leucine-Rich Repeat Kinase 2 (LRRK2) are associated with a significantly enhanced risk for Parkinson disease, the second most common human neurodegenerative disorder. Despite major efforts, our understanding of LRRK2 biological function and regulation remains rudimentary. In the present study we analyze LRRK2 mRNA and protein expression in sub-populations of human peripheral blood mononuclear cells (PBMCs). LRRK2 mRNA and protein was found in circulating CD19+ B cells and in CD14+ monocytes, whereas CD4+ and CD8+ T cells were devoid of LRRK2 mRNA. Within CD14+ cells the CD14+CD16+ sub-population of monocytes exhibited high levels of LRRK2 protein, in contrast to CD14+CD16- cells. However both populations expressed LRRK2 mRNA. As CD14+CD16+ cells represent a more mature subset of monocytes, we monitored LRRK2 expression after in vitro treatment with various stress factors known to induce monocyte activation. We found that IFN-Îł in particular robustly increased LRRK2 mRNA and protein levels in monocytes concomitant with a shift of CD14+CD16â cells towards CD14+CD16+cells. Interestingly, the recently described LRRK2 inhibitor IN-1 attenuated this shift towards CD14+CD16+ after IFN-Îł stimulation. Based on these findings we speculate that LRRK2 might have a role in monocyte maturation. Our results provide further evidence for the emerging role of LRRK2 in immune cells and regulation at the transcriptional and translational level. Our data might also reflect an involvement of peripheral and brain immune cells in the disease course of PD, in line with increasing awareness of the role of the immune system in PD
Reshaping of Bulbar Odor Response by Nasal Flow Rate in the Rat
The impact of respiratory dynamics on odor response has been poorly studied at the olfactory bulb level. However, it has been shown that sniffing in the behaving rodent is highly dynamic and varies both in frequency and flow rate. Bulbar odor response could vary with these sniffing parameter variations. Consequently, it is necessary to understand how nasal airflow can modify and shape odor response at the olfactory bulb level.To assess this question, we used a double cannulation and simulated nasal airflow protocol on anesthetized rats to uncouple nasal airflow from animal respiration. Both mitral/tufted cell extracellular unit activity and local field potentials (LFPs) were recorded. We found that airflow changes in the normal range were sufficient to substantially reorganize the response of the olfactory bulb. In particular, cellular odor-evoked activities, LFP oscillations and spike phase-locking to LFPs were strongly modified by nasal flow rate.Our results indicate the importance of reconsidering the notion of odor coding as odor response at the bulbar level is ceaselessly modified by respiratory dynamics
The GenTree Dendroecological Collection, tree-ring and wood density data from seven tree species across Europe
The dataset presented here was collected by the GenTree project (EU-Horizon 2020), which aims to improve the use of forest genetic resources across Europe by better understanding how trees adapt to their local environment. This dataset of individual tree-core characteristics including ring-width series and whole-core wood density was collected for seven ecologically and economically important European tree species: silver birch (Betula pendula), European beech (Fagus sylvatica), Norway spruce (Picea abies), European black poplar (Populus nigra), maritime pine (Pinus pinaster), Scots pine (Pinus sylvestris), and sessile oak (Quercus petraea). Tree-ring width measurements were obtained from 3600 trees in 142 populations and whole-core wood density was measured for 3098 trees in 125 populations. This dataset covers most of the geographical and climatic range occupied by the selected species. The potential use of it will be highly valuable for assessing ecological and evolutionary responses to environmental conditions as well as for model development and parameterization, to predict adaptability under climate change scenarios
- âŠ