322 research outputs found

    ModĂšle multi-agents pour la simulation de la dynamique de carbone Ă  l'Ă©chelle du terroir villageois

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    Un systĂšme multi-agents (SMA) a Ă©tĂ© conçu et mis en oeuvre en vue d'Ă©tudier la dynamique des ressources organiques et azotĂ©e d'un terroir africain. Les simulations rĂ©alisĂ©es ont permis de mesurer l'impact des modes de gestion sur les ressources dans le long terme. Trois types d'enquĂȘtes ont Ă©tĂ© nĂ©cessaires pour collecter les donnĂ©es nĂ©cessaires. Un premier modĂšle Ă  l'Ă©chelle de la parcelle a permis de simuler le stockage du carbone et de l'azote dans les sols et dans la biomasse vĂ©gĂ©tale. Ensuite la dĂ©finition des rĂšgles individuelles et collectives de dĂ©cision et de gestion des exploitations agricoles et du terroir ont nĂ©cessitĂ© des enquĂȘtes approfondies avec les principaux groupes utilisant le terroir. . Pour la conception informatique du modĂšle, le formalisme UML a Ă©tĂ© utilisĂ©. La reprĂ©sentation statique et dynamique du modĂšle a Ă©tĂ© formalisĂ©e sur la plate forme de modĂ©lisation CORMAS. . La mĂ©thode dĂ©veloppĂ©e est appelĂ©e MIROT ModĂ©lisation IntĂ©grĂ©e de la dynamique des Ressources Organiques et analyse de viabilitĂ© de Terroirs agro-sylvo-pastoraux des savanes ouest africaines). Le modĂšle MIROT utilise un fond de carte du terroir avec des contraintes spatiales pour simuler le fonctionnement de celui-ci

    Kerr-microresonator solitons from a chirped background

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    We demonstrate protected single-soliton formation and operation in a Kerr microresonator using a phase-modulated pump laser. Phase modulation gives rise to spatially varying effective loss and detuning parameters, which in turn lead to an operation regime in which multi-soliton degeneracy is lifted and a single soliton is the only observable behavior. Direct excitation of single solitons is indicated by observed reversal of the characteristic 'soliton step.' Phase modulation also enables precise control of the soliton pulse train's properties, and measured dynamics agree closely with simulations. We show that the technique can be extended to high repetition-frequency Kerr solitons through subharmonic phase modulation. These results facilitate straightforward generation and control of Kerr-soliton microcombs for integrated photonics systems

    Anti-proliferative effect of Scoparia dulcis L. against bacterial and fungal strains

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    Scoparia dulcis L. was sequentially extracted with hexane, chloroform and methanol and soaked with aqueous-acetone (80%) to check for its antimicrobial activities against five bacterial and four fungal strains.250ÎŒg of each extract loaded on a whatman paper disc exhibited significant antimicrobial activities on all the fungus and against Gram-negative and Gram-positive bacteria. Therefore, P. mirabilis is less sensitive to all the extracts while B. cereus, a Ăą-lactamase producer bacterium, was resistant to the activity of the polar methanol and aqueous-acetone extracts. By the microdilution method, the most active extracts were chloroform extract on B. cereus with minimal inhibitory concentration (MIC) of 1.56 mg/ml and Aqueous-acetone extract on S. typhimurium (MIC = 1.56 mg/ml); the antifungal activity was strongest for hexane extract (MIC = 6.25 mg/ml) on both A. niger and P. roquefortii.Keywords: Scoparia dulcis, Antibacterial, Antifungal, Polyphenols

    Multi Agents Model for carbone dynamic simulation at village area scale

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    Un systĂšme multi-agents (SMA) a Ă©tĂ© conçu et mis en Ɠuvre en vue d’étudier la dynamique des ressources organiques et azotĂ©e d’un terroir africain. Les simulations rĂ©alisĂ©es ont permis de mesurer l’impact des modes de gestion sur les ressources dans le long terme. Trois types d’enquĂȘtes ont Ă©tĂ© nĂ©cessaires pour collecter les donnĂ©es nĂ©cessaires. Un premier modĂšle Ă  l’échelle de la parcelle a permis de simuler le stockage du carbone et de l’azote dans les sols et dans la biomasse vĂ©gĂ©tale. Ensuite la dĂ©finition des rĂšgles individuelles et collectives de dĂ©cision et de gestion des exploitations agricoles et du terroir ont nĂ©cessitĂ© des enquĂȘtes approfondies avec les principaux groupes utilisant le terroir. . Pour la conception informatique du modĂšle, le formalisme UML a Ă©tĂ© utilisĂ©. La reprĂ©sentation statique et dynamique du modĂšle a Ă©tĂ© formalisĂ©e sur la plate forme de modĂ©lisation CORMAS. . La mĂ©thode dĂ©veloppĂ©e est appelĂ©e MIROT ModĂ©lisation IntĂ©grĂ©e de la dynamique des Ressources Organiques et analyse de viabilitĂ© de Terroirs agro-sylvo-pastoraux des savanes ouest africaines). Le modĂšle MIROT utilise un fond de carte du terroir avec des contraintes spatiales pour simuler le fonctionnement de celui-ci

    Phase-coherent microwave-to-optical link with a self-referenced microcomb

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    Precise measurements of the frequencies of light waves have become common with mode-locked laser frequency combs1. Despite their huge success, optical frequency combs currently remain bulky and expensive laboratory devices. Integrated photonic microresonators are promising candidates for comb generators in out-of-the-lab applications, with the potential for reductions in cost, power consumption and size. Such advances will significantly impact fields ranging from spectroscopy and trace gas sensing to astronomy, communications and atomic time-keeping. Yet, in spite of the remarkable progress shown over recent years, microresonator frequency combs (‘microcombs’) have been without the key function of direct f–2f self-referencing, which enables precise determination of the absolute frequency of each comb line. Here, we realize this missing element using a 16.4 GHz microcomb that is coherently broadened to an octave-spanning spectrum and subsequently fully phase-stabilized to an atomic clock. We show phase-coherent control of the comb and demonstrate its low-noise operation

    Phase Coherent Link of an Atomic Clock to a Self-Referenced Microresonator Frequency Comb

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    The counting and control of optical cycles of light has become common with modelocked laser frequency combs. But even with advances in laser technology, modelocked laser combs remain bulk-component devices that are hand-assembled. In contrast, a frequency comb based on the Kerr-nonlinearity in a dielectric microresonator will enable frequency comb functionality in a micro-fabricated and chip-integrated package suitable for use in a wide-range of environments. Such an advance will significantly impact fields ranging from spectroscopy and trace gas sensing, to astronomy, communications, atomic time keeping and photonic data processing. Yet in spite of the remarkable progress shown over the past years, microresonator frequency combs ("microcombs") have still been without the key function of direct f-2f self-referencing and phase-coherent frequency control that will be critical for enabling their full potential. Here we realize these missing elements using a low-noise 16.4 GHz silicon chip microcomb that is coherently broadened from its initial 1550 nm wavelength and subsequently f-2f self-referenced and phase-stabilized to an atomic clock. With this advance, we not only realize the highest repetition rate octave-span frequency comb ever achieved, but we highlight the low-noise microcomb properties that support highest atomic clock limited frequency stability

    Multiplex serum protein analysis reveals potential mechanisms and markers of response to hyperimmune caprine serum in systemic sclerosis

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    BACKGROUND: Hyperimmune caprine serum (HICS) is a novel biological therapy with potential benefit for skin in established diffuse cutaneous systemic sclerosis. Here we report multiplex protein analysis of blood samples from a placebo-controlled phase II clinical trial and explore mechanisms of action and markers of response. METHODS: Patients were treated with HICS (n = 10) or placebo (n = 10) over 26 weeks, with follow-up open-label treatment to 52 weeks in 14 patients. Serum or plasma samples at baseline, 26 and 52 weeks were analysed using multiplex or individual immunoassays for 41 proteins. Patterns of change were analysed by clustering using Netwalker 1.0, Pearson coefficient and significance analysis of microarrays (SAM) correction. RESULTS: Cluster analysis, SAM multiplex testing and paired comparison of individual analytes identified proteins that were upregulated or downregulated during treatment with HICS. There was upregulation of the hypothalamo-pituitary-adrenal axis after HICS treatment evidenced by increases in α-MSH and ACTH in cases treated with HICS. Interestingly, significant increase in PIIINP was associated with HICS treatment and improved MRSS suggesting that this may be a marker of extracellular matrix turnover. Other relevant factors reduced in HICS-treated patients compared with controls, although not reaching statistical significance included COMP, CCL2, IL6, TIMP2, Fractalkine and TGFÎČ1 levels. CONCLUSIONS: Our results suggest mechanisms of action for HICS, including upregulation of α-MSH, that has been shown to be anti-fibrotic in preclinical models, and possible markers to be included in future trials targeting skin in diffuse cutaneous systemic sclerosis. TRIAL REGISTRATION: Eudract, No. 2007-003122-24. ClinTrials.gov, No. NCT00769028 . Registered 7 October 2008
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