469 research outputs found

    Fisher profiles and perceptions of sea turtle-fishery interactions: case study of East Coast Peninsular Malaysia

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    The paper focuses on coastal fisheries, particularly examining sea turtle-fishery interactions and determining the socioeconomic profile and perception of local fishers about sea turtle issues along the East Coast of Peninsular Malaysia.Turtle fisheries, Nature conservation, Coastal fisheries, Man-induced effects, ISEW, Malaysia, Malaya, Pahang, Malaysia, Malaya, Kelantan, Malaysia, Malaya, Terengganu,

    Room temperature ferromagnetism in chemically synthesized ZnO rods

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    We report structural and magnetic properties of pure ZnO rods using X-ray diffraction (XRD), magnetization hysteresis (M-H) loop and near edge x-ray fine structure spectroscopy (NEXAFS) study at O K edge. Sample of ZnO was prepared by co-precipitation method. XRD and selective area electron diffraction measurements infer that ZnO rods exhibit a single phase polycrystalline nature with wurtzite lattice. Field emission transmission electron microscopy, field emission scanning electron microscopy micrographs infers that ZnO have rod type microstructures with dimension 200 nm in diameter and 550 nm in length. M-H loop studies performed at room temperature display room temperature ferromagnetism in ZnO rods. NEXAFS study reflects absence of the oxygen vacancies in pure ZnO rods.Comment: 8 Pages, 3 Figure

    Nanocrystalline Ge Flash Memories: Electrical Characterization and Trap Engineering

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    Conventional floating gate non-volatile memories (NVMs) present critical issues for device scalability beyond the sub-90 nm node, such as gate length and tunnel oxide thickness reduction. Nanocrystalline germanium (nc-Ge) quantum dot flash memories are fully CMOS compatible technology based on discrete isolated charge storage nodules which have the potential of pushing further the scalability of conventional NVMs. Quantum dot memories offer lower operating voltages as compared to conventional floating-gate (FG) Flash memories due to thinner tunnel dielectrics which allow higher tunneling probabilities. The isolated charge nodules suppress charge loss through lateral paths, thereby achieving a superior charge retention time. Despite the considerable amount of efforts devoted to the study of nanocrystal Flash memories, the charge storage mechanism remains obscure. Interfacial defects of the nanocrystals seem to play a role in charge storage in recent studies, although storage in the nanocrystal conduction band by quantum confinement has been reported earlier. In this work, a single transistor memory structure with threshold voltage shift, Vth, exceeding ~1.5 V corresponding to interface charge trapping in nc-Ge, operating at 0.96 MV/cm, is presented. The trapping effect is eliminated when nc-Ge is synthesized in forming gas thus excluding the possibility of quantum confinement and Coulomb blockade effects. Through discharging kinetics, the model of deep level trap charge storage is confirmed. The trap energy level is dependent on the matrix which confines the nc-Ge.Singapore-MIT Alliance (SMA

    A study of semi-inclusive charmless BπXB \to \pi X decays

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    We study semi-inclusive charmless decays BπXB \to \pi X in detail, such as Bˉ0π±(0)X\bar B^0 \to \pi^{\pm (0)} X, B0π±(0)XB^0 \to \pi^{\pm (0)} X, B±π±(0)XB^{\pm} \to \pi^{\pm (0)} X, where XX does not contain a charm (anti)quark. We find that the process Bˉ0πX\bar B^0 \to \pi^- X (B0π+XB^0 \to \pi^+ X) can be particularly useful for determination of the CKM matrix element Vub|V_{ub}|. We calculate and present the branching ratio (BR) of Bˉ0πX\bar B^0 \to \pi^- X as a function of Vub|V_{ub}|, with an estimate of possible uncertainties. It is expected that the BR is an order of 10410^{-4}. Our estimation indicates that one can phenomenologically determine Vub|V_{ub}| with reasonable accuracy by measuring the BR of Bˉ0πX\bar B^0 \to \pi^- X (B0π+XB^0 \to \pi^+ X).Comment: 18 pages, 7 figures; Revtex; version accepted for publication in Eur. Phys. J.

    Aquatic resources valuation and policies for poverty elimination in the lower Mekong basin: final report volume 1 project implementation and outcomes

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    This report presents the final outputs of the project on "Aquatic resources valuation and policies for poverty elimination in the Lower Mekong Basin". Volume 1 summarizes the implementation process, outcomes and key lessons of the project. The project was implemented in partnership with the Dept of Fisheries, Cambodia. It was developed to improve understanding of the economic and social values of aquatic resources, as a step towards improving institutional and policy processes in the Lower Mekong Basin so that resource management decisions better reflect the interests of the rural poor.Resource management, Aquatic environment, Living resources, Cambodia, Southeast, Southeast Asia, Mekong R.,

    Effect of Annealing Time on the Power Conversion Efficiency of Silicon Nanowire Based Solar Cell Prepared by Wet Diffusion Technique

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    In this study, we present the effect of annealing time on the power conversion efficiency (PCE) of silicon nanowire (SiNW) based solar cell prepared by wet diffusion technique. P-typed SiNW arrays were prepared by metal assisted chemical etching (MACE) method using aqueous solution including HF (4.6 M) and AgNO3 (0.02 M). The prepared SiNWs have V-shaped structures with the wall thickness in a range from 10-50 nm and the average length of 1.5 μm. The reflectance of SiNW array remained less than 20 % and lower compared to that of planar Si (38 %) in the range of 300-1000 nm due to the subwavelength light trapping and collective light scattering interactions. The wet diffusion technique was used to making p-n junctions in solar cell structure with different annealing time at 850 ℃. The obtained results demonstrated that the PCE increases when increasing the annealing time from 30 min to 45 min then decreases with 60 min. The highest PCE obtained with cell annealed for 45 min was measured to be 2.2 % and about 2 times and 5 times higher compared to cell annealed for 60 min and 30 min, respectively. The dependence of PCE on the annealing time is attributed to the difference in the doping diffusion depth

    Kondo lattice model with a direct exchange interaction between localized moments

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    We study the Kondo lattice model with a direct antiferromagnetic exchange interaction between localized moments. Ferromagnetically long-range ordered state coexisting with the Kondo screening shows a continuous quantum phase transition to the Kondo singlet state. We obtain the value of the critical point where the magnetizations of the localized moments and the conduction electrons vanish. The magnetization curves yield a universal critical exponent independent of the filling factors and the strength of the interaction between localized moments. It is shown that the direct exchange interaction between localized moments introduces another phase transition from an antiferromagnetic ordering to a ferromagnetic ordering for small Kondo exchange interaction. We also explain the local minimum of the Kondo temperature in recent experiments.Comment: 6 pages, 5 figures, final versio

    Quantum Conductance in Silver Nanowires: correlation between atomic structure and transport properties

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    We have analyzed the atomic arrangements and quantum conductance of silver nanowires generated by mechanical elongation. The surface properties of Ag induce unexpected structural properties, as for example, predominance of high aspect ratio rod-like wires. The structural behavior was used to understand the Ag quantum conductance data and the proposed correlation was confirmed by means of theoretical calculations. These results emphasize that the conductance of metal point contacts is determined by the preferred atomic structures and, that atomistic descriptions are essential to interpret the quantum transport behavior of metal nanostructures.Comment: 4 pages, 4 figure

    Magnetic phenomena in 5d transition metal nanowires

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    We have carried out fully relativistic full-potential, spin-polarized, all-electron density-functional calculations for straight, monatomic nanowires of the 5d transition and noble metals Os, Ir, Pt and Au. We find that, of these metal nanowires, Os and Pt have mean-field magnetic moments for values of the bond length at equilibrium. In the case of Au and Ir, the wires need to be slightly stretched in order to spin polarize. An analysis of the band structures of the wires indicate that the superparamagnetic state that our calculations suggest will affect the conductance through the wires -- though not by a large amount -- at least in the absence of magnetic domain walls. It should thus lead to a characteristic temperature- and field dependent conductance, and may also cause a significant spin polarization of the transmitted current.Comment: 7 pages, 5 figure

    Self-organized model of cascade spreading

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    We study simultaneous price drops of real stocks and show that for high drop thresholds they follow a power-law distribution. To reproduce these collective downturns, we propose a minimal self-organized model of cascade spreading based on a probabilistic response of the system elements to stress conditions. This model is solvable using the theory of branching processes and the mean-field approximation. For a wide range of parameters, the system is in a critical state and displays a power-law cascade-size distribution similar to the empirically observed one. We further generalize the model to reproduce volatility clustering and other observed properties of real stocks.Comment: 8 pages, 6 figure
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