924 resultados para Interval signals and systems
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SOUSA,M.B.C. et al. Reproductive Patterns and Birth Seasonality in a South-American Breeding Colony of Common Marmosets, Callithrix jacchus. Primates, v.40, n.2, p. 327-336, Apr. 1999.
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microRNA (miRNA) mediated regulation of protein expression has emerged as an important mechanism in T-cell physiology, from development and survival to activation, proliferation, and differentiation. One of the major classes of proteins involved in these processes are cytokines, which are both key input signals and major products of T-cell function. Here, we summarize the current data on the molecular cross-talk between cytokines and miRNAs: how cytokines regulate miRNA expression, and how specific miRNAs control cytokine production in T cells. We also describe the inflammatory consequences of deregulating the miRNA/cytokine axis in mice and humans. We believe this topical area will have key implications for immune modulation and treatment of autoimmune pathology.
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A simple but efficient voice activity detector based on the Hilbert transform and a dynamic threshold is presented to be used on the pre-processing of audio signals -- The algorithm to define the dynamic threshold is a modification of a convex combination found in literature -- This scheme allows the detection of prosodic and silence segments on a speech in presence of non-ideal conditions like a spectral overlapped noise -- The present work shows preliminary results over a database built with some political speech -- The tests were performed adding artificial noise to natural noises over the audio signals, and some algorithms are compared -- Results will be extrapolated to the field of adaptive filtering on monophonic signals and the analysis of speech pathologies on futures works
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HERMES is one of the projects in the European ATT Programme. The ATT Programme (or DRIVE II as it is frequently referred to) is an application oriented Community Research and Technological Development Programme that has been conceived and implemented with the objective of contributing to the competitiveness of Europe and to its social and economic cohesion. An important means toward this end is the direct collaboration between different European sector actors: road authorities, fleet operators, road user representatives, industry, and research institutions. DRIVE I has already achieved an important step into this direction. DRIVE II aims at providing a framework that encourages even closer cooperation through large scale international pilot projects that will require common functional and technical specifications for the systems to be implemented at least between the partners directly involved in any project. HERMES is one of the so-called "supporting R&D projects" that provides strategies, algorithms and systems for the pilot applications
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Abstract. Dendritic cells are antigen presenting cells that provide a vital link between the innate and adaptive immune system. Research into this family of cells has revealed that they perform the role of coordinating T-cell based immune responses, both reactive and for generating tolerance. We have derived an algorithm based on the functionality of these cells, and have used the signals and differentiation pathways to build a control mechanism for an artificial immune system. We present our algorithmic details in addition to some preliminary results, where the algorithm was applied for the purpose of anomaly detection. We hope that this algorithm will eventually become the key component within a large, distributed immune system, based on sound immunological concepts.
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Oculo-auriculo-vertebral spectrum (OAVS, OMIM 164 210) is a developmental disorder primarily involving structures derived from the first and second pharyngeal arches during embryogenesis. The phenotype is clinically heterogeneous and is typically characterised by abnormal development of the ear, mandible anomalies and defects of the vertebral column. OAVS may occur as a multiple congenital abnormality, and associated findings include anomalies of the eye, brain, heart, kidneys and other organs and systems. Both genetic and environmental factors are thought to contribute to this craniofacial condition, however, the mechanisms are still poorly understood. Here, we present a review of the literature on OAVS, discussing what is known about the aetiology, candidate loci, possible mechanisms and the range of clinical features that characterise this condition. We also comment on some important aspects of recurrence risk counselling to aid clinical management.
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Barrett's esophagus is the major risk factor for esophageal adenocarcinoma. It has a low but non-neglectable risk, high surveillance costs and no reliable risk stratification markers. We sought to identify early biomarkers, predictive of Barrett's malignant progression, using a meta-analysis approach on gene expression data. This in silico strategy was followed by experimental validation in a cohort of patients with extended follow up from the Instituto Português de Oncologia de Lisboa de Francisco Gentil EPE (Portugal). Bioinformatics and systems biology approaches singled out two candidate predictive markers for Barrett's progression, CYR61 and TAZ. Although previously implicated in other malignancies and in epithelial-to-mesenchymal transition phenotypes, our experimental validation shows for the first time that CYR61 and TAZ have the potential to be predictive biomarkers for cancer progression. Experimental validation by reverse transcriptase quantitative PCR and immunohistochemistry confirmed the up-regulation of both genes in Barrett's samples associated with high-grade dysplasia/adenocarcinoma. In our cohort CYR61 and TAZ up-regulation ranged from one to ten years prior to progression to adenocarcinoma in Barrett's esophagus index samples. Finally, we found that CYR61 and TAZ over-expression is correlated with early focal signs of epithelial to mesenchymal transition. Our results highlight both CYR61 and TAZ genes as potential predictive biomarkers for stratification of the risk for development of adenocarcinoma and suggest a potential mechanistic route for Barrett's esophagus neoplastic progression.
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The key to better nutrient efficiency is to simultaneously improve uptake and decrease losses. This study sought to achieve this balance using sorbent additions and manure nutrients (spent poultry litter; SL) compared with results obtained using conventional sources (Conv; urea nitrogen, N; and phosphate–phosphorus; P). Two experiments were conducted. Firstly, a phosphorus pot trial involving two soils (sandy and clay) based on a factorial design (Digitaria eriantha/Pennisetum clandestinum). Subsequently, a factorial N and P field trial was conducted on the clay soil (D. eriantha/Lolium rigidum). In the pot trial, sorbent additions (26.2 g of hydrotalcite [HT] g P− 1) to the Conv treatment deferred P availability (both soils) as did SL in the sandy soil. In this soil, P delivery by the Conv treatments declined rapidly, and began to fall behind the HT and SL treatments. Addition of HT increased post-trial Colwell P. In the field trial low HT-rates (3.75 and 7.5 g of HT g P− 1) plus bentonite, allowed dry matter production and nutrient uptake to match that of Conv treatments, and increased residual mineral-N. The SL treatments performed similarly to (or better than) Conv treatments regarding nutrient uptake. With successive application, HT forms may provide better supply profiles than Conv treatments. Our findings, combined with previous studies, suggest it is possible to use manures and ion-exchangers to match conventional N and P source productivity with lower risk of nutrient losses.
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International audience
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Virus and soil borne pathogens negatively impact on the production of potatoes in tropical highland and sub-tropical environments, limiting supply of an increasingly popular and important vegetable in these regions. It is common for latent disease infected seed tubers or field grown cuttings to be used as potato planting material. We utilised an International Potato Centre technique, using aeroponic technology, to produce low cost mini-tubers in tropical areas. The system has been optimised for increased effectiveness in tropical areas. High numbers of seed tubers of cultivar Sebago (630) and Nicola per m2 (>900) were obtained in the first generation, and the system is capable of producing five crops of standard cultivars in every two years. Initial results indicate that quality seed could be produced by nurseries and farmers, therefore contributing to the minimisation of soil borne diseases in an integrated management plan. This technology reduces seed production costs, benefiting seed and potato growers. © ISHS.
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Two field experiments were carried out in Taveuni, Fiji to study the effects of mucuna (Mucuna pruriens) and grass fallow systems at 6 and 12 month durations on changes in soil properties (Experiment 1) and taro yields (Experiment 2). Biomass accumulation of mucuna fallow crop was significantly higher (P<0.05) than grass fallow crop at both 6 and 12 month durations. The longer fallow duration resulted in higher (P<0.05) total soil organic carbon, total soil nitrogen and earthworm numbers regardless of fallow type. Weed suppression in taro grown under mucuna was significantly greater (P<0.05) than under natural grass fallow. Taro grown under mucuna fallow significantly outyielded taro grown under grass fallow (11.8 vs. 8.8 t ha-1). Also, the gross margin of taro grown under mucuna fallow was 52% higher than that of taro grown under grass fallow. © ISHS.
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Intrusion Detection Systems (IDSs) provide an important layer of security for computer systems and networks, and are becoming more and more necessary as reliance on Internet services increases and systems with sensitive data are more commonly open to Internet access. An IDS’s responsibility is to detect suspicious or unacceptable system and network activity and to alert a systems administrator to this activity. The majority of IDSs use a set of signatures that define what suspicious traffic is, and Snort is one popular and actively developing open-source IDS that uses such a set of signatures known as Snort rules. Our aim is to identify a way in which Snort could be developed further by generalising rules to identify novel attacks. In particular, we attempted to relax and vary the conditions and parameters of current Snort rules, using a similar approach to classic rule learning operators such as generalisation and specialisation. We demonstrate the effectiveness of our approach through experiments with standard datasets and show that we are able to detect previously undetected variants of various attacks. We conclude by discussing the general effectiveness and appropriateness of generalisation in Snort based IDS rule processing. Keywords: anomaly detection, intrusion detection, Snort, Snort rules
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Dendritic cells are antigen presenting cells that provide a vital link between the innate and adaptive immune system. Research into this family of cells has revealed that they perform the role of coordinating T-cell based immune responses, both reactive and for generating tolerance. We have derived an algorithm based on the functionality of these cells, and have used the signals and differentiation pathways to build a control mechanism for an artificial immune system. We present our algorithmic details in addition to some preliminary results, where the algorithm was applied for the purpose of anomaly detection. We hope that this algorithm will eventually become the key component within a large, distributed immune system, based on sound imnological concepts.
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There are enormous benefits for any organisation from practising sound records management. In the context of a public university, the importance of good records management includes: facilitating the achievement the university’s mandate; enhancing efficiency of the university; maintaining a reliable institutional memory; promoting trust; responding to an audit culture; enhancing university competitiveness; supporting the university’s fiduciary duty; demonstrating transparency and accountability; and fighting corruption. Records scholars and commentators posit that effective recordkeeping is an essential underpinning of good governance. Although there is a portrayal of positive correlation, recordkeeping struggles to get the same attention as that given to the governance. Evidence abounds of cases of neglect of recordkeeping in universities and other institutions in Sub-Saharan Africa. The apparent absence of sound recordkeeping provided a rationale for revisiting some universities in South Africa and Malawi in order to critically explore the place of recordkeeping in an organisation’s strategy in order to develop an alternative framework for managing records and documents in an era where good governance is a global agenda. The research is a collective case study in which multiple cases are used to critically explore the relationship between recordkeeping and governance. As qualitative research that belongs in the interpretive tradition of enquiry, it is not meant to suggest prescriptive solutions to general recordkeeping problems but rather to provide an understanding of the challenges and opportunities that arise in managing records and documents in the world of governance, audit and risk. That is: what goes on in the workplace; what are the problems; and what alternative approaches might address any existing problem situations. Research findings show that some institutions are making good use of their governance structures and other drivers for recordkeeping to put in place sound recordkeeping systems. Key governance structures and other drivers for recordkeeping identified include: laws and regulations; governing bodies; audit; risk; technology; reforms; and workplace culture. Other institutions are not managing their records and documents well despite efforts to improve their governance systems. They lack recordkeeping capacity. Areas that determine recordkeeping capacity include: availability of records management policy; capacity for digital records; availability of a records management unit; senior management support; level of education and training of records management staff; and systems and procedures for storage, retrieval and dispositions of records. Although this research reveals that the overall recordkeeping in the selected countries has slightly improved compared with the situation other researchers found a decade ago, it remains unsatisfactory and disjointed from governance. The study therefore proposes governance recordkeeping as an approach to managing records and documents in the world of governance, audit and risk. The governance recordkeeping viewpoint considers recordkeeping as a governance function that should be treated in the same manner as other governance functions such as audit and risk management. Additionally, recordkeeping and governance should be considered as symbiotic elements of a strategy. A strategy that neglects recordkeeping may not fulfil the organisation’s objectives effectively.