368 research outputs found

    Long dephasing time and high temperature ballistic transport in an InGaAs open quantum dot

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    We report on measurements of the magnetoconductance of an open circular InGaAs quantum dot between 1.3K and 204K. We observe two types of magnetoconductance fluctuations: universal conductance fluctuations (UCFs), and 'focusing' fluctuations related to ballistic trajectories between openings. The electron phase coherence time extracted from UCFs amplitude is larger than in GaAs/AlGaAs quantum dots and follows a similar temperature dependence (between T^-1 and T^-2). Below 150K, the characteristic length associated with 'focusing' fluctuations shows a slightly different temperature dependence from that of the conductivity.Comment: 6 pages, 4 figures, proceedings of ICSNN2002, to appear in Physica

    The reliability of eyetracking to assess attentional bias to threatening words in healthy individuals

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    Eyetracking is commonly used to investigate attentional bias. Although some studies have investigated the internal consistency of eyetracking, data are scarce on the testā€“retest reliability and agreement of eyetracking to investigate attentional bias. This study reports the testā€“retest reliability, measurement error, and internal consistency of 12 commonly used outcome measures thought to reflect the different components of attentional bias: overall attention, early attention, and late attention. Healthy participants completed a preferential-looking eyetracking task that involved the presentation of threatening (sensory words, general threat words, and affective words) and nonthreatening words. We used intraclass correlation coefficients (ICCs) to measure testā€“retest reliability (ICC \u3e .70 indicates adequate reliability). The ICCs(2, 1) ranged from ā€“.31to.71. Reliability varied according to the outcome measure and threat word category. Sensory words had a lower mean ICC (.08) than either affective words (.32) or general threat words (.29). A longer exposure time was associated with higher testā€“retest reliability. All of the outcome measures, except second-run dwell time, demonstrated low measurement error (\u3c6%). Most of the outcome measures reported high internal consistency (Ī± \u3e.93). Recommendations are discussed for improving the reliability of eyetracking tasks in future research

    Cryptic Diversity and Conservation of Gopher Frogs across the Southeastern United States

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    Identifying cryptic biodiversity is fundamental to evolutionary biology and to conservation efforts. This study investigated range-wide genetic diversity of Gopher Frogs, Lithobates capito, across the southeastern United States coastal plain to determine implications for taxonomy and conservation. We collected data for two mtDNA regions in 21 populations to identify genetic structure across the geographic distribution of the species. Based on population genetic, phylogenetic, and genealogical analyses, we recovered three reciprocally monophyletic mtDNA lineages corresponding to mainland coastal plain populations and two lineages within peninsular Florida. Breakpoints for these lineages did not occur in previously identified hotspots of amphibian phylogeographic breaks and did not follow currently recognized subspecies designations. We recommend these lineages be recognized as separate distinct population segments and be considered separately by the U.S. Fish and Wildlife Service for listing under the Endangered Species Act. Additionally, we propose an evolutionary hotspot for amphibians that deserves further attentio

    PENERAPAN SEMANTIC SIMILARITY PADA KRIPTOGRAFI SUATU DOKUMEN TEKS DALAM BAHASA INDONESIA

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    Penerapan kriptografi digunakan untuk memberikan keamanan pada dokumen penting. Kriptografi terdiri dari proses ekripsi dan deskripsi. Enkripsi suatudokumen teks telah banyak diterapkan dengan berbagai macam metode untukmengubah dokumen asli menjadi dokumen yang terkunci, setiapmetode/algoritma memiliki tingkat kerumitan yang berbeda. Namun, penerapanenkripsi yang terlalu mencolok dapat mengundang hacker untuk berusahamemecahkan enkripsi tersebut. Artikel ini mengembangkan pendekatan untukpenerapan enkripsi pada kriptografi suatu dokumen teks dalam bahasa Indonesiadengan mengenkripsi dokumen teks asli ke bentuk dokumen teks yangmengandung kata/kalimat lain dengan tingkat similarity tertentu. Penerapanenkripsi ini, diharapkan menjadi lebih efektif dan tidak menarik perhatian hacker,karena pada penelitian ini enkripsi yang dihasilkan masih berbentuk teksdokumen utuh, tetapi memiliki makna yang berbeda dengan dokumen aslinya.Pada artikel ini dibuat ilustrasi untuk pendekatan yang dikembangkan untukproses enkripsi

    Evolution of associative learning in chemical networks

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    Organisms that can learn about their environment and modify their behaviour appropriately during their lifetime are more likely to survive and reproduce than organisms that do not. While associative learning ā€“ the ability to detect correlated features of the environment ā€“ has been studied extensively in nervous systems, where the underlying mechanisms are reasonably well understood, mechanisms within single cells that could allow associative learning have received little attention. Here, using in silico evolution of chemical networks, we show that there exists a diversity of remarkably simple and plausible chemical solutions to the associative learning problem, the simplest of which uses only one core chemical reaction. We then asked to what extent a linear combination of chemical concentrations in the network could approximate the ideal Bayesian posterior of an environment given the stimulus history so far? This Bayesian analysis revealed the ā€™memory tracesā€™ of the chemical network. The implication of this paper is that there is little reason to believe that a lack of suitable phenotypic variation would prevent associative learning from evolving in cell signalling, metabolic, gene regulatory, or a mixture of these networks in cells

    Interactive Modelling of Buildings in Google Earth and GIS: a 3D Tool for Urban Planning (Tunjuk Island, Indonesia)

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    3D modelling of buildings in Google Earth in Batam city, Indonesia is very important for knowledge about facility, infrastructure, and others.Three-dimensional (3D) visualisations are an interesting method for representing model outcomes. This research In Tunjuk island with coordinate, at Latitude: 0.984123Ā°, and Longitude: 104.225606Ā°, with technical terms, there are two alternative routes for implementation, and they both share the same starting stage. In (Figure 5) visible visual measurements of the master plan that has been made has a length 141.99 metre and width 54.25 metre with location at Latitude 0.984593Ā° and Longitude 104.228073Ā°. In (Figure 5) visible visual measurements of the master plan that has been made has a length 92.96 metre and width 135.46  metre with location at Latitude 0.984593Ā° and Longitude 104.228073Ā°. This paper presented a rapid visualisation tool for supporting the joint decision making in evaluation of design/renewal proposals in Batam City, Tunjuk Island, Indonesia. 3D building using Google Earth (GE) and combaining Geographic Information System (GIS) system be done officially on a sampling or auditing basis by a professional body or by researchers, or it could be done by volunteers and user groups

    Far upstream element binding protein 1 binds the internal ribosomal entry site of enterovirus 71 and enhances viral translation and viral growth

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    Enterovirus 71 (EV71) is associated with severe neurological disorders in children, and has been implicated as the infectious agent in several large-scale outbreaks with mortalities. Upon infection, the viral RNA is translated in a cap-independent manner to yield a large polyprotein precursor. This mechanism relies on the presence of an internal ribosome entry site (IRES) element within the 5ā€²-untranslated region. Virusā€“host interactions in EV71-infected cells are crucial in assisting this process. We identified a novel positive IRES trans-acting factor, far upstream element binding protein 1 (FBP1). Using binding assays, we mapped the RNA determinants within the EV71 IRES responsible for FBP1 binding and mapped the protein domains involved in this interaction. We also demonstrated that during EV71 infection, the nuclear protein FBP1 is enriched in cytoplasm where viral replication occurs. Moreover, we showed that FBP1 acts as a positive regulator of EV71 replication by competing with negative ITAF for EV71 IRES binding. These new findings may provide a route to new anti-viral therapy
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