48 research outputs found

    Localization and electrical characterization of interconnect open defects

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    A technique for extracting the electrical and topological parameters of open defects in process monitor lines is presented. The procedure is based on frequency-domain measurements performed at both end points of the line. The location as well as the resistive value of the open defect are derived from attenuation and phase shift measurements. The characteristic defect-free impedance of the line and its propagation constant are considered to be unknowns, and their values are also derived from the above measurements. In this way, the impact of process parameter variations on the proposed model is diminished. The experimental setup required to perform the characterization measurements and a simple graphical procedure to determine the defect and line parameters are presented. Experimental results show a good agreement between the predicted location of the open and its real location, found by optical beam induced resistance change inspection. Errors smaller than 2% of the total length of the line have been observed in the experiments.Postprint (published version

    Multilocus Microsatellite Typing (MLMT) of Strains from Turkey and Cyprus Reveals a Novel Monophyletic L. donovani Sensu Lato Group

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    In eastern Mediterranean, leishmaniasis represents a major public health problem with considerable impact on morbidity and potential to spread. Cutaneous leishmaniasis (CL) caused by L. major or L. tropica accounts for most cases in this region although visceral leishmaniasis (VL) caused by L. infantum is also common. New foci of human CL caused by L. donovani complex strains were recently described in Cyprus and Turkey. Herein we analyzed Turkish strains from human CL foci in Çukurova region (north of Cyprus) and a human VL case in Kuşadasi. These were compared to Cypriot strains that were previously typed by Multilocus Enzyme Electrophoresis (MLEE) as L. donovani MON-37. Nevertheless, they were found genetically distinct from MON-37 strains of other regions and therefore their origin remained enigmatic. A population study was performed by Multilocus Microsatellite Typing (MLMT) and the profile of the Turkish strains was compared to previously analyzed L. donovani complex strains. Our results revealed close genetic relationship between Turkish and Cypriot strains, which form a genetically distinct L. infantum monophyletic group, suggesting that Cypriot strains may originate from Turkey. Our analysis indicates that the epidemiology of leishmaniasis in this region is more complicated than originally thought

    Infection Parameters in the Sand Fly Vector That Predict Transmission of Leishmania major

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    To identify parameters of Leishmania infection within a population of infected sand flies that reliably predict subsequent transmission to the mammalian host, we sampled groups of infected flies and compared infection intensity and degree of metacyclogenesis with the frequency of transmission. The percentage of parasites within the midgut that were metacyclic promastigotes had the highest correlation with the frequency of transmission. Meta-analysis of multiple transmission experiments allowed us to establish a percent-metacyclic “cutoff” value that predicted transmission competence. Sand fly infections initiated with variable doses of parasites resulted in correspondingly altered percentages of metacyclic promastigotes, resulting in altered transmission frequency and disease severity. Lastly, alteration of sand fly oviposition status and environmental conditions at the time of transmission also influenced transmission frequency. These observations have implications for transmission of Leishmania by the sand fly vector in both the laboratory and in nature, including how the number of organisms acquired by the sand fly from an infection reservoir may influence the clinical outcome of infection following transmission by bite

    Human Cellular Immune Response to the Saliva of Phlebotomus papatasi Is Mediated by IL-10-Producing CD8+ T Cells and Th1-Polarized CD4+ Lymphocytes

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    Cutaneous leishmaniasis affects millions of people worldwide and is caused by protozoa of the genus Leishmania. The parasite is transmitted during sand fly bites. While probing the skin for a blood meal, vectors salivate into the host's skin. Sand fly saliva contains several components that increase hemorrhage and interfere with the host's inflammatory response. Data obtained in mice originally indicate that immunization against saliva protected from leishmaniasis supporting possibility that leishmaniasis could be prevented by a vaccine based on sand fly saliva. Herein we investigated the nature and the importance of the cellular immune response developed against sand fly saliva by individuals at risk of cutaneous leishmaniasis due to Leishmania major. We demonstrated that the immunity against saliva is dominated by the activation of lymphocytes producing a suppressive cytokine called IL-10. These data may preclude the protective effect of sand fly saliva pre-exposure in humans. Further experiments revealed that the production of IL-10 masked the presence of a second kind of lymphocytes producing IFN-γ, a rather protective cytokine. The latter finding highlights the importance of the identification of the proteins activating the latter lymphocytes in order to develop vaccines based on selected proteins from the saliva of sand flies

    Context maximizing: Finding mdl decision trees

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    We present an application of the context weighting algorithm. Our objective is to classify objects with decision trees. The best tree will be searched for with the Minimum Description Length Principle. In order to find these trees, we modified the context weighting algorithm.

    Switching between two universal source coding algorithms

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    This paper discusses a switching method which can be used to combine two sequential universal source coding algorithms. The switching method treats these two algorithms as black-boxes and can only use their estimates of the probability distributions for the consecutive symbols of the source sequence. Three weighting algorithms based on this switching method are presented. Empirical results show that all three weighting algorithms give a performance better than the performance of the source coding algorithms they combine.

    The switching method: elaborations

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    The switching method [4] is a scheme which combines two universal source coding algorithms. The two universal source coding algorithms both estimate the probability distribution of the source symbols, and the switching method allows an encoder to choose which of the two probability distributions it uses for every source symbol. The switching algorithm is an efficient weighting algorithm that uses this switching method. This paper focuses on the companion algorithm, the algorithm running in parallel to the main CTW-algorithm. 1 The switching method: A short introduction The switching method [4] defines a way in which two modeling algorithms can be combined. Consider a source sequence x1,..., xN. Suppose that two sequential modeling algorithms, A and B, run both along the entire source sequence, and give for every symbol an estimate of its probability distribution. These modeling algorithms could be memoryless estimators, estimators for fixed tree models, or entire universal source coding algorithms on their own. At each moment the encoder in the switching method use
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