1,884 research outputs found

    Immunisation against gemetes and asexual erythrocytic stages of rodent malaria parasites

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    It was possible to block the transmission of an infection of a rodent malaria parasite Plasmodium yoelii nigeriensis to Anopheles stephensi mosquitoes by immunising mice with a vaccine containing formalin-fixed gametes. A single dose of the gamete vaccine containing 2x106 male gametes given intravenously was effective in blocking completely the transmission of a blood induced challenge infection. The vaccine was also effective when given intramuscularly and immunity was found to last at least six months. Transmission blocking immunity was found to reside in a serum factor, probably antibody, and to be directed against extracellular gametes, acting on them in the gut of the mosquito while gametocytes in the circulation of the vertebrate host remained unaffected. A limited study involving experimental vaccination with formalin-fixed erythrocytic parasites was also undertaken. A crude erythrocytic stage vaccine protected mice against the asexual blood stages of a challenge infection and protection was found to be enhanced by killed Bordetella pertussis organisms used as an adjuvant. The gamete vaccine afforded partial protection against the disease. Immunisation with asexual parasites alone showed that this protection was due to the presence of asexual forms as contaminants and that anti-gamete immunity is stage specific. Factors affecting the infectiousness of gametocytes in a natural infection were also investigated. It was found that mice elaborate anti-gamete immunity in response to an infection which renders it non-infectious to mosquitoes after about the fifth day. In addition, gametocytes display a pattern of altered viability during the course of an infection where they lose the capacity to exflagellate. The possibility of this being either a manifestation of an intrinsic cycle of gametocyte development or immunity mediated by non-specific non-antibody factors that affect gametocytes within red cells is discussed

    A control theorem for pp-adic automorphic forms and Teitelbaum's L\mathcal{L}-invariant

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    In this article, we describe an efficient method for computing Teitelbaum's pp-adic L\mathcal{L}-invariant. These invariants are realized as the eigenvalues of the L\mathcal{L}-operator acting on a space of harmonic cocycles on the Bruhat-Tits tree T\mathcal{T}, which is computable by the methods of Franc and Masdeu described in \cite{fm}. The main difficulty in computing the L\mathcal{L}-operator is the efficient computation of the pp-adic Coleman integrals in its definition. To solve this problem, we use overconvergent methods, first developed by Darmon, Greenberg, Pollack and Stevens. In order to make these methods applicable to our setting, we prove a control theorem for pp-adic automorphic forms of arbitrary even weight. Moreover, we give computational evidence for relations between slopes of L\mathcal{L}-invariants of different levels and weights for p=2p=2.Comment: 26 page

    Copyright and the Value of the Public Domain: an empirical assessment

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    This Report is the outcome of a knowledge exchange scheme which brings together academics (from the disciplines of law, media & communication studies, management and economics), policy makers from the Intellectual Property Office (an executive agency of the Department for Business, Innovation and Skills) and media businesses (in particular transmedia SMEs) to generate and disseminate new knowledge about the use of public domain works

    Nonlinear Interactions Between Gravitational Radiation and Modified Alfven Modes in Astrophysical Dusty Plasmas

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    We present an investigation of nonlinear interactions between Gravitational Radiation and modified Alfv\'{e}n modes in astrophysical dusty plasmas. Assuming that stationary charged dust grains form neutralizing background in an electron-ion-dust plasma, we obtain the three wave coupling coefficients, and calculate the growth rates for parametrically coupled gravitational radiation and modified Alfv\'{e}n-Rao modes. The threshold value of the gravitational wave amplitude associated with convective stabilization is particularly small if the gravitational frequency is close to twice the modified Alfv\'en wave-frequency. The implication of our results to astrophysical dusty plasmas is discussed.Comment: A few typos corrected. Published in Phys. Rev.

    Design and fabrication of a SIO2/ST-cut quartz love mode surface acoustic wave transducer for operation in liquid media

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    Love mode surface acoustic wave (SAW) transducers were designed and fabricated by depositing silicon dioxide on a ST-cut quartz crystal wafer using r.f. magnetron sputtering. Two different propagation directions have been investigated by aligning the SAW finger pattern along the x-axis propagation direction and the direction orthogonal to the x-axis of the ST-cut quartz crystal. The latter, in which the propagation mode is dominantly the Love mode, shows promising characteristics for use as a high frequency SAW transducer because of high acoustic wave propagation velocity and electromechanical coupling coefficient. Phase and group velocity, capacitance per unit length of electrodes, insertion loss and input admittance, of two transducers, with different alignments, have been measured and compared

    Solid-Like Electrolyte Based on Cellulosic Biomass Materials for Cost Effective and Eco-Friendly Lithium Ion Batteries Function as a Sustainable Energy Source

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    The demand for the sustainable energy sources has increased due to the environmental issues, durability and cost. Lithium ion rechargeable batteries (LiBs) are widely known as a renewable energy source. LiBs can be converted to effective sustainable energy sources when they are modified to acquire the criterias of sustainable energy sources other than rechargeability. In the present, there is an inclination to develop all-solid state and solid-like electrolytes for LiBs due to the environmental and safety issues resulted by liquid electrolytes. In this work, an experiment was carried out to design a lithium ion battery using a solid-like electrolyte based on cellulosic biomass. Cellulosic biomass is very abundant, low cost and eco-friendly. Cellulose is a crucial extractable material of cellulosic biomass and carboxymethyl cellulose can be synthesized from cellulose. In here, one component of the electrolyte synthesized is lithium dichlorocarboxymethyl cellulose (LiCMC) using cellulose, LiOH and trichloroacetic acid. Tricholoacetic acid can be extracted from disinfected byproducts in water. LiCMC has various advantages over typical sodium carboxymethyl cellulose. LiCMC has additional chlorine atoms and lithium ions which directly promote the segmental motion diffusion of lithium ions. The prepared LiCMC was crosslinked with β-cyclodextrin (BCD) using citric acid. In here, BCD is very efficient because it is environmentally friendly and its cavities enhance the lithium ion conduction. Another component in this electrolyte is LiCMC grafted mesoporous silica (MS). The cavities of MS enhance the lithium ion conductivity and the robustness of MS improves the durability of the battery. In the preparation of the electrolyte, citric acid cross linked LiCMC-BCD and LiCMC grafted MS were incorporated together. The resulted hydrogel was dipped in LiCl aqueous solution and then it was used as the electrolyte. Graphite/graphene oxide (GO) composite was used as the anode and Cobalt oxide-GO hydrogel was used as the cathode of the prepared cell. The performance of the assembled cell was analyzed using charge-discharge curves. The assembled cell showed an initial current density of 1.5 mA cm-2 and maximum current density of 4.5 mA cm-2 in charging and initial current density of 0.90 mA cm-2 and minimum current density of 0.20 mA cm-2 in discharging. The synthesized materials mentioned in above were analyzed using FTIR-ATR data. The eco-friendliness, cost effectiveness of the materials chosen in cell preparation and the desirable cell performance induce the viability to develop LiBs as sustainable energy sources.Keywords: Sustainable energy sources, Cellulosic biomass, Solid-like electrolytes, Lithium dichlorocarboxymethyl cellulose, β-cyclodextri

    Active pixel sensor having intra-pixel charge transfer with analog-to-digital converter

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    An imaging device formed as a monolithic complementary metal oxide semiconductor Integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node and an analog-to-digital converter formed in the substrate connected to the output of the readout circuit

    Active pixel sensor having intra-pixel charge transfer with analog-to-digital converter

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    An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node and an analog-to-digital converter formed in the substrate connected to the output of the readout circuit
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