3,623 research outputs found
Inteligencia artificial para sistemas colaborativos
Me han ofrecido la posibilidad de desarrollar un trabajo de fin de grado tutorizado junto al responsable o tutor de la Universidad de Alicante: Francisco Javier Ferrández. El objetivo de dicho proyecto es desarrollar un sistema colaborativo multi-robot heterogéneo que de forma autónoma les permita alcanzar los objetivos definidos por un usuario y cooperar con él en la búsqueda y optimización de una solución. O simplemente que coopere con dicho usuario para lograr una interacción. De la misma manera, si fuese necesario, se desarrollaría robótica de enjambre o dicho de otra manera, una misma inteligencia artificial controlando simultáneamente varias entidades robóticas, con tal de dar soluciones a distintos problemas
DISPOSITIFS D'APPUI A DES PROCESSUS LOCAUX D'INNOVATION ET INTEGRATION DES PAYSANS PAUVRES DANS LES MONTAGNES SECHES D'AMERIQUE CENTRALE : UNE DIFFICILE ARTICULATION
N° ISBN - 978-2-7380-1284-5International audienceEn Amérique centrale les zones de montagnes tropicales sèches se caractérisent par la pauvreté de leurs populations paysannes, des degrés élevés d'insécurité alimentaire et de vulnérabilité environnementale, et une place relativement marginale dans les sociétés et dans les économies nationales. A partir des années 1990, les interventions de développement en faveur de ces zones, menées par une diversité d'institutions, se sont multipliées autour d'objectifs tels que « contribuer au développement durable », « favoriser l'intégration sociale et économique des plus pauvres », ou encore « renforcer les capacités des petits producteurs à être acteurs de leur développement ». Malgré des résultats tangibles auprès de certains « bénéficiaires » directs, force est de constater qu'il existe un écart important entre ces objectifs et les effets réels des interventions en termes d'intégration sociale des plus pauvres ou d'émergence de processus de développement durablement portés par les populations concernées. Cette communication présente les résultats d'une recherche en cours menée sous l'angle d'une analyse des dispositifs et des pratiques d'intervention des agents, et en amont des conceptions auxquelles ils renvoient, pour comprendre dans quelle mesure ils contribuent (ou non) à créer les conditions pour favoriser des processus locaux d'innovation en tant que formes de réponse aux difficultés auxquelles les producteurs et familles sont confrontées
Direct observation of irradiation-induced nanocavity shrinkage in Si
Nanocavities in Si substrates, formed by conventional H implantation and thermal annealing, are shown to evolve in size during subsequent Si irradiation. Both ex situ and in situ analytical techniques were used to demonstrate that the mean nanocavity diameter decreases as a function of Si irradiation dose in both the crystalline and amorphous phases. Potential mechanisms for this irradiation-induced nanocavity evolution are discussed. In the crystalline phase, the observed decrease in diameter is attributed to the gettering of interstitials. When the matrix surrounding the cavities is amorphized, cavity shrinkage may be mediated by one of two processes: nanocavities can supply vacancies into the amorphous phase and/or the amorphous phase may flow plastically into the nanocavities. Both processes yield the necessary decrease in density of the amorphous phase relative to crystalline material
Consommation élevée de β-carotène : Un risque de certains cancers diminué chez les non-fumeuses, mais augmenté chez les fumeuses
Structural and nuclear characterizations of defects created by noble gas implantation in silicon oxide
Thermally grown silicon oxide layer was implanted at room temperature with 300keV Xe at fluences ranging from 0.5 to 5x10Xe/cm. Bubbles created after Xe-implantation provided a low-k silicon oxide that has potential use as a dielectric material for interconnects in Si integrated circuits. Transmission Electron Microscopy (TEM), Rutherford Backscattering Spectrometry (RBS) and Positron Annihilation Spectroscopy (PAS) were used to provide a comprehensive characterization of defects (bubbles, vacancy, gas atoms and other types of defects) created by Xe implantation in layer. These measurements suggest that the bubbles observed with TEM for all fluences were a consequence of the interaction between Xe and vacancies (V), with complexes created in the zone where V and Xe profiles overlap. Negatively charged defects such as (, and ) are also created after implantation
Association between Melanocytic Nevi and Risk of Breast Diseases: The French E3N Prospective Cohort
Background: While melanocytic nevi have been associated with genetic factors and childhood sun exposure, several observations also suggest a potential hormonal influence on nevi. To test the hypothesis that nevi are associated with breast tumor risk, we explored the relationships between number of nevi and benign and malignant breast disease risk. Methods and Findings: We prospectively analyzed data from E3N, a cohort of French women aged 40–65 y at inclusion in 1990. Number of nevi was collected at inclusion. Hazard ratios (HRs) for breast cancer and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression models. Associations of number of nevi with personal history of benign breast disease (BBD) and family history of breast cancer were estimated using logistic regression. Over the period 15 June 1990–15 June 2008, 5,956 incident breast cancer cases (including 5,245 invasive tumors) were ascertained among 89,902 women. In models adjusted for age, education, and known breast cancer risk factors, women with “very many” nevi had a significantly higher breast cancer risk (HR = 1.13, 95% CI = 1.01–1.27 versus “none”; ptrend = 0.04), although significance was lost after adjustment for personal history of BBD or family history of breast cancer. The 10-y absolute risk of invasive breast cancer increased from 3,749 per 100,000 women without nevi to 4,124 (95% CI = 3,674–4,649) per 100,000 women with “very many” nevi. The association was restricted to premenopausal women (HR = 1.40, ptrend = 0.01), even after full adjustment (HR = 1.34, ptrend = 0.03; phomogeneity = 0.04), but did not differ according to breast cancer type or hormone receptor status. In addition, we observed significantly positive dose–response relationships between number of nevi and history of biopsy-confirmed BBD (n = 5,169; ptrend<0.0001) and family history of breast cancer in first-degree relatives (n = 7,472; ptrend = 0.0003). The main limitations of our study include self-report of number of nevi using a qualitative scale, and self-reported history of biopsied BBD. Conclusions: Our findings suggest associations between number of nevi and the risk of premenopausal breast cancer, BBD, and family history of breast cancer. More research is warranted to elucidate these relationships and to understand their underlying mechanisms. Please see later in the article for the Editors' Summar
Structural effect of heavy ion irradiation on GdBaCuO ceramics
The influence of twin boundaries as sinks on defects induced by 480 keV Kr ion irradiation in GdBaCuO crystals was observed in situ at 40 and 300 K. The interaction of the dislocations with the twin boundaries followed on a video recording. A crystalline to amorphous transition was observed above a total fluence of ∼ 4 - 5 x 10^12 Kr/cm2. A comparison between orthorhombic (Os) crystals and a monoclinic structure (Ms) (close to Os and whose parameters were calculated) shows that the behaviour of irradiation-induced extended defects does not depend on a small initial deformation of the orthorhombic cell. In both case, an occasional orthorhombic (or monoclinic) to tetragonal phase transition only occurs when the amorphization process has begun
Lifestyle, dietary factors and antibody levels to oral bacteria in cancer-free participants of a European cohort study
Background—Increasing evidence suggests that oral microbiota play a pivotal role in chronic diseases, in addition to the well-established role in periodontal disease. Moreover, recent studies suggest that oral bacteria may also be involved in carcinogenesis; periodontal disease has been linked several cancers. In this study, we examined whether lifestyle factors have an impact on antibody levels to oral bacteria.
Methods—Data on demographic characteristics, lifestyle factors, and medical conditions were obtained at the time of blood sample collection. For the current analysis, we measured antibody levels to 25 oral bacteria in 395 cancer-free individuals using an immunoblot array. Combined total immunglobin G (IgG) levels were obtained by summing concentrations for all oral bacteria measured.
Results—IgG antibody levels were substantially lower among current and former smokers (1697 and 1677 ng/mL, respectively) than never smokers (1960 ng/mL; p-trend = 0.01), but did not vary by other factors, including BMI, diabetes, physical activity, or by dietary factors, after adjusting for age, sex, education, country and smoking status. The highest levels of total IgG were found among individuals with low education (2419 ng/mL).
Conclusions—Our findings on smoking are consistent with previous studies and support the notion that smokers have a compromised humoral immune response. Moreover, other major factors known to be associated with inflammatory markers, including obesity, were not associated with antibody levels to a large number of oral bacteria
Carbohydrate Intake in the Etiology of Crohn's Disease and Ulcerative Colitis
Background: Diet may have a role in the etiology of inflammatory bowel disease. In previous studies, the associations between increased intakes of carbohydrates, sugar, starch, and inflammatory bowel disease are inconsistent. However, few prospective studies have investigated the associations between these macronutrients and incident Crohn's disease (CD) or ulcerative colitis (UC). Methods: A total of 401,326 men and women were recruited between 1991 and 1998. At recruitment, dietary intakes of carbohydrate, sugar, and starch were measured using validated food frequency questionnaires. The cohort was monitored identifying participants who developed incident CD or UC. Cases were matched with 4 controls, and odds ratios were calculated for quintiles of total carbohydrate, sugar, and starch intakes adjusted for total energy intake, body mass index, and smoking. Results: One hundred ten participants developed CD, and 244 participants developed UC during follow-up. The adjusted odds ratio for the highest versus the lowest quintiles of total carbohydrate intake for CD was 0.87, 95% CI = 0.24 to 3.12 and for UC 1.46, 95% CI = 0.62 to 3.46, with no significant trends across quintiles for either (CD, Ptrend = 0.70; UC, Ptrend = 0.41). Similarly, no associations were observed with intakes of total sugar (CD, Ptrend = 0.50; UC, Ptrend = 0.71) or starch (CD, Ptrend = 0.69; UC, Ptrend = 0.17). Conclusions: The lack of associations with these nutrients is in agreement with many case–control studies that have not identified associations with CD or UC. As there is biological plausibility for how specific carbohydrates could have an etiological role in inflammatory bowel disease, future epidemiological work should assess individual carbohydrates, although there does not seem to be a macronutrient effect
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