4,354 research outputs found

    Conductance of 1D quantum wires with anomalous electron-wavefunction localization

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    We study the statistics of the conductance gg through one-dimensional disordered systems where electron wavefunctions decay spatially as âˆŁÏˆâˆŁâˆŒexp⁥(−λrα)|\psi| \sim \exp (-\lambda r^{\alpha}) for 0<α<10 <\alpha <1, λ\lambda being a constant. In contrast to the conventional Anderson localization where âˆŁÏˆâˆŁâˆŒexp⁥(−λr)|\psi| \sim \exp (-\lambda r) and the conductance statistics is determined by a single parameter: the mean free path, here we show that when the wave function is anomalously localized (α<1\alpha <1) the full statistics of the conductance is determined by the average and the power α\alpha. Our theoretical predictions are verified numerically by using a random hopping tight-binding model at zero energy, where due to the presence of chiral symmetry in the lattice there exists anomalous localization; this case corresponds to the particular value α=1/2\alpha =1/2. To test our theory for other values of α\alpha, we introduce a statistical model for the random hopping in the tight binding Hamiltonian.Comment: 6 pages, 8 figures. Few changes in the presentation and references updated. Published in PRB, Phys. Rev. B 85, 235450 (2012

    First in situ observations of soft bottom megafauna from the Cascais Canyon head

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    We report the first in situ observations of soft bottom megafauna from the Cascais Canyon head. Observations were collected opportunistically during three technical dives with the ROV Luso between 460-805 m at two locations distanced 1,230 m. The habitats were clas-sified as upper bathyal fine mud. The soft bottom fauna was dominated by burrows of Nephrops norvegicus reaching up to 2.9 burrows/m2, a common habitat along the Portu-guese continental margin. To our knowledge, densities are the highest ever reported for depths below 300 m. The ichthyofauna at the upper Cascais Canyon is a mixture of lower shelf and upper bathyal species, including Phycis blennoides, Scyliorhynus canicula, Coe-lorhynchus labiatus/occa and Chimaera monstrosa. Bait release attracted Myxine glutinosa. Surveys in other geological settings of the Cascays Canyon are required to understand more comprehensively the diversity of its sessile and vagile biodiversity

    PENYULUHAN TENTANG KELESTARIAN LINGKUNGAN, BAHAYA SAMPAH PLASTIK DAN PENGGUNAAN GADGET DI SELURUH SD DESA MENGESTA

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    We want to educate the younger brothers in SD N Mengesta to use gadgets well and conducive to this counseling and socialization can give good influence to children in hopes of growing the sense of environmental care in themselves, family, peers, and the community around. Gadgets are currently a much-needed technology in society because personal devices can accelerate the work of Merka, fast in communicating, and looking for information. In addition to the means of communication, gadgets also become the need for entertainment for man itself because they can play games with only a device. Mengesta Village is one of the villages located in the Penebel sub-district, Tabanan Regency. The Program of KKN activities in Mengesta village has been carried out well thanks to the cooperation of the community, students, and the full support of the village chief Mengesta. The work program that runs during the activity is counseling and socialization about the use of plastic waste and gadgets. Plastic waste becomes a problem that nowadays gets more attention than many countries. As a material that takes a long time to decompose, plastic products will undoubtedly continue to accumulate

    Estimation of interdomain flexibility of N-terminus of factor H using residual dipolar couplings

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    Characterization of segmental flexibility is needed to understand the biological mechanisms of the very large category of functionally diverse proteins, exemplified by the regulators of complement activation, that consist of numerous compact modules or domains linked by short, potentially flexible, sequences of amino acid residues. The use of NMR-derived residual dipolar couplings (RDCs), in magnetically aligned media, to evaluate interdomain motion is established but only for two-domain proteins. We focused on the three N-terminal domains (called CCPs or SCRs) of the important complement regulator, human factor H (i.e. FH1-3). These domains cooperate to facilitate cleavage of the key complement activation-specific protein fragment, C3b, forming iC3b that no longer participates in the complement cascade. We refined a three-dimensional solution structure of recombinant FH1-3 based on nuclear Overhauser effects and RDCs. We then employed a rudimentary series of RDC datasets, collected in media containing magnetically aligned bicelles (disk-like particles formed from phospholipids) under three different conditions, to estimate interdomain motions. This circumvents a requirement of previous approaches for technically difficult collection of five independent RDC datasets. More than 80% of conformers of this predominantly extended three-domain molecule exhibit flexions of < 40 °. Such segmental flexibility (together with the local dynamics of the hypervariable loop within domain 3), could facilitate recognition of C3b via initial anchoring and eventual reorganization of modules to the conformation captured in the previously solved crystal structure of a C3b:FH1-4 complex

    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 – the ability to detect correlated features of the environment – 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 ’memory traces’ 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

    Multifrequency Observations of Radio Pulse Broadening and Constraints on Interstellar Electron Density Microstructure

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    We have made observations of 98 low-Galactic-latitude pulsars to measure pulse broadening caused by multipath propagation through the interstellar medium. Data were collected with the 305-m Arecibo telescope at four radio frequencies between 430 and 2380 MHz. We used a CLEAN-based algorithm to deconvolve interstellar pulse broadening from the measured pulse shapes. We employed two distinct pulse broadening functions (PBFs): PBF1_1 is appropriate for a thin screen of scattering material between the Earth and a pulsar, while PBF2_2 is appropriate for scattering material uniformly distributed along the line of sight from the Earth to a pulsar. We found that some observations were better fit by PBF1_1 and some by PBF2_2. Pulse broadening times (τd\tau_d) are derived from fits of PBFs to the data, and are compared with the predictions of a smoothed model of the Galactic electron distribution. Several lines of sight show excess broadening, which we model as clumps of high density scattering material. A global analysis of all available data finds that the pulse broadening scales with frequency, Îœ\nu, as \taud \propto\nu^{-\alpha} where α∌3.9±0.2\alpha\sim 3.9\pm 0.2. This is somewhat shallower than the value α=4.4\alpha=4.4 expected from a Kolmogorov medium, but could arise if the spectrum of turbulence has an inner cutoff at ∌\sim 300--800 km. A few objects follow particularly shallow scaling laws (the mean scaling index \meanalpha \sim 3.1 \pm 0.1 and ∌3.8±0.2 \sim 3.8 \pm 0.2 respectively for the case of PBF1_1 and PBF2_2), which may arise from large scale refraction or from the truncation of scattering screens transverse to the Earth--pulsar line of sight.Comment: Accepted for publication in the Astrophysical Journal; 32 pages, 11 figure

    Decoherence, Correlation, and Unstable Quantum States in Semiclassical Cosmology

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    It is demonstrated that almost any S-matrix of quantum field theory in curved spaces posses an infinite set of complex poles (or branch cuts). These poles can be transformed into complex eigenvalues, the corresponding eigenvectors being Gamow vectors. All this formalism, which is heuristic in ordinary Hilbert space, becomes a rigorous one within the framework of a properly chosen rigged Hilbert space. Then complex eigenvalues produce damping or growing factors. It is known that the growth of entropy, decoherence, and the appearance of correlations, occur in the universe evolution, but only under a restricted set of initial conditions. It is proved that the damping factors allow to enlarge this set up to almost any initial conditions.Comment: 19 pgs. Latex fil

    Tea tourism as a marketing tool: a strategy to develop the image of Sri Lanka as an attractive tourism destination

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    Tourism is one of the world’s largest industries as well a provider of employments over to 100 million populations around the world. Niche tourism refers to strategy that specific tourism product personalized to meet the needs of a particular tourist segment. Hence Tea tourism has been identified as one niche Tourism segment emerged with novel concept of sustainable and nature based eco-friendly tourism. Research objective is to identify the potentials to promote Sri Lanka as a tea tourism destination with special reference to Badulla and Nuwara Eliya districts by investigating the tea tourists’ attitudes, expectations and destination attributes and local community involvement for tea tourism. Sample consists with 173 tea tourists and structured questionnaire and semi structured interviews were adopted in primary data collection. The numerous potentials have been identified which will be in capable of promoting tea tourism. Destination image building with the brand name of “Ceylon Tea”, global promotional campaigns with the collaboration of Social Media Marketing tools as well introducing sustainable tourism experience packages has been recommended.</span

    Practices Followed to Manage Plastic Waste including Shopping Bags and Lunch Sheets in Sri Lanka: A Preliminary Study in Western Province

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    Although plastics have made the workings of our lives easier, it has created many different environmental and social problems due to poor management practices. The problem of plastic waste has been exacerbated due to various regulations that have been introduced from time to time for the sustainable management of plastic waste. However, those are not properly implemented. The main objective of this study is to examine the best practices in Sri Lanka for the management of plastic waste, including shopping bags and lunch sheets (PBLS). Further, the study illustrated the prevailing and possible alternatives for polythene products in Sri Lanka and weaknesses in the identification of alternatives. The study was conducted in the Western Province covering three districts: Colombo, Gampaha and Kalutara. Data collection was conducted through different structured questionnaire surveys, key informant interviews and a major workshop from a sample of 1314 respondents. Results revealed that 59% of households in the survey confirm that they were discouraged from switching to alternatives as a result of freely available low-density polyethylene (LDPE) bags in the market. Also, 67% of the households and 74% of the supermarkets pointed out that, the current polythene bag usage was higher prior to the ban, due to the poor strength and quality of the bag. Further, the study reveals that ‘Extended Producer Responsibility (EPR)’ has the potential to influence material management systems and prevent pollution and has been successfully tested in many countries around the world. DOI: http://doi.org/10.31357/fhss/vjhss.v07i01.0
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