503 research outputs found

    Electromagnetic Force in Dispersive and Transparent Media

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    A hydrodynamic-type, macroscopic theory was set up recently to simultaneously account for dissipation and dispersion of electromagnetic field, in nonstationary condensed systems of nonlinear constitutive relations~\cite{JL}. Since it was published in the letter format, some algebra and the more subtle reasonings had to be left out. Two of the missing parts are presented in this paper: How algebraically the new results reduce to the known old ones; and more thoughts on the range of validity of the new theory, especially concerning the treatment of dissipation.Comment: 10 pages, 0 figur

    Perceptions of Clickbait: A Q-Methodology Approach

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    Clickbait is “content whose main purpose is to attract attention and encourage visitors to click on a link to a particular web page” (“clickbait,” n.d.). The term is also generally used to refer specifically to the attention-grabbing headlines. Critics of clickbait argue that clickbait is shallow, misleading, and ubiquitous – “a new word that has become synonymous with online journalism” (Frampton, 2015). It is the subject of a small, but growing number of studies in disciplines ranging from linguistics, communications, and information sciences. Palau-Sampio (2016) analyzed linguistic strategies associated with tabloid journalism in the Spanish digital newspaper Elpais.com, concluding that there is a trend towards lower quality news reporting. In their research on Danish news sites, Blom & Hansen (2015) identified forward-referencing, specifically the use of empty pronouns to create an information gap, as a feature of clickbait headlines. Chen, Conroy & Rubin (2015) proposed that automatic identification of clickbait could draw upon three types of features: a) lexico-semantic and pragmatic linguistic patterns (e.g. unresolved pronouns, affective and suspenseful language, action words, overuse of numerals, and reverse narratives), b) incongruent image placement with a possible emotional load, and c) user reading and commenting behavior. An effort in automated identification of clickbait by Potthast, et al. (2016) achieved 79% accuracy on Twitter tweets. But debate still rages over what the word actually means (Gardiner, 2015)

    Energetic Instability Unjams Sand and Suspension

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    Jamming is a phenomenon occurring in systems as diverse as traffic, colloidal suspensions and granular materials. A theory on the reversible elastic deformation of jammed states is presented. First, an explicit granular stress-strain relation is derived that captures many relevant features of sand, including especially the Coulomb yield surface and a third-order jamming transition. Then this approach is generalized, and employed to consider jammed magneto- and electro-rheological fluids, again producing results that compare well to experiments and simulations.Comment: 9 pages 2 fi

    Particle-based platforms for malaria vaccines

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    Recombinant subunit vaccines in general are poor immunogens likely due to the small size of pep-tides and proteins, combined with the lack or reduced presentation of repetitive motifs and missing complementary signal(s) for optimal triggering of the immune response. Therefore, recombinant sub-unit vaccines require enhancement by vaccine delivery vehicles in order to attain adequate protective immunity. Particle-based delivery platforms, including particulate antigens and particulate adjuvants,are promising delivery vehicles for modifying the way in which immunogens are presented to both theinnate and adaptive immune systems. These particle delivery platforms can also co-deliver non-specific immunostimodulators as additional adjuvants. This paper reviews efforts and advances of the Particle-based delivery platforms in development of vaccines against malaria, a disease that claims over 600,000lives per year, most of them are children under 5 years of age in sub-Sahara Africa

    DEVELOPMENT OF RECOMBINANT PROTEIN BASED CHEMICAL CONJUGATE MALARIA VACCINES TARGETING THE PRE-ERYTHROCYTIC STAGE, TRANSMISSION BLOCKING, OR BOTH

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    The development of a Plasmodium falciparum malaria vaccine is critical for future control and elimination programs. Recombinant protein based chemical conjugate vaccines, covering different parasite stages, are being developed due to complexity of the parasite and sub-optimal immunogenicity of recombinant malaria proteins in humans, respectively. Chemical conjugation of recombinant malaria proteins to carrier proteins improves their immunogenicity in animal studies. A transmission blocking vaccine comprised of the ookinete protein Pfs25 chemically conjugated to Pseudomonas aeruginosa ExoProtein A (EPA) is currently being developed for pilot scale cGMP production. Bulk lots of Pfs25 and EPA have already been produced and released following cGMP. Appropriate analytical assays are being evaluated for both in-process and bulk release of the Pfs25-EPA conjugate vaccine. One critical assay already evaluated for determining the average mass is analytical size exclusion HPLC coupled with multi-angle light scattering. Phase 1 human clinical trials are planned for 2011. Another biological target of interest is the circumsporozoite protein (CSP), the most abundant and immunogenic protein on the surface of the sporozoite. A recombinant nearly full-length CSP has been produced in the methylotrophic yeast Pichia pastoris containing a bioengineered free thiol for chemical conjugation to various carrier proteins, including a chemically conjugated form of Pfs25. This recombinant protein based chemical conjugation platform, in combination with better adjuvant selection, will improve the potential for developing an efficacious malaria vaccine

    Hydrogels Of Chiral–Nematic Cellulose Nanocrystals And Nanochitin

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    The mechanical strength of hydrogels and aerogels produced from inorganic nano- and microparticles has been out of limits for those based on organic counterparts. Control over the nanoscale architecture of such materials is a possible answer to this challenge, which can even expand properties and functions, including mechano-optical activity. Here we show unprecedented levels of strength by controlling the assembly architecture of cellulose nanocrystals (CNC) and nanochitin (NCh), nanoscaled building blocks presenting anisometry and high intrinsic strength. High yield (\u3e85%) and low-energy deconstruction of never-dried residual marine biomass is proposed following partial deacetylation and microfluidization. This process results in NCh of ultrahigh axial size that produce highly entangled networks upon pH shift. Viscoelastic and strong hydrogels are formed by ice templating upon freezing and thawing with simultaneous cross-linking. Slow supercooling and ice nucleation at −20 °C make ice crystals grow slowly and exclude nanochitin and cross-linkers, becoming spatially confined at the interface. At a NCh concentration as low as 0.4 wt %, highly viscoelastic hydrogels are formed, at least an order of magnitude larger compared to those measured for the strongest chitin-derived hydrogels reported so far. The water absorption capacity of the hydrogels reaches a value of 466 g/g. Moreover, our results demonstrate that chiral-nematically ordered hydrogels can lead to aerogels with controlled meso- and microstructures that replicate the liquid crystalline phase transitions of the hydrogels. The obtained architectures are feasible by systematically varying the long-range order of the aqueous CNC dispersions, from mostly isotropic to completely anisotropic. The resultant aerogels display strong coupling between the mesopore fraction and selective light reflection (iridescence) as a function of mechanical load. Specifically, we find that the mechanical performance associated with pore compression under load is greatly enhanced by chiral nematic ordering. These new limits in the mechanical properties of CNC- and NCh-based hydrogels and aerogels point to new structural considerations for the synthesis of porous constructs that exploit the inherent long-range order of such unique building blocks

    A Dual-current Method for Characterizing Common-Mode Loop Impedance

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    The definition of common-mode loop impedance is proposed instead of the ambiguous definition of common-mode impedance. Moreover, a non-invasive measurement method to characterize the common-mode loop impedance using dual clamp-on current probe is presented herein. The frequency responses of the current probes are de-embedded through a calibration procedure. Independent direct measurements using a network analyzer corroborate the validity of the Dual-Current-Probe Method

    Rotating Superconductors and the London Moment: Thermodynamics versus Microscopics

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    Comparing various microscopic theories of rotating superconductors to the conclusions of thermodynamic considerations, we traced their marked difference to the question of how some thermodynamic quantities (the electrostatic and chemical potentials) are related to more microscopic ones: The electron's the work function, mean-field potential and Fermi energy -- certainly a question of general import. After the correct identification is established, the relativistic correction for the London Moment is shown to vanish, with the obvious contribution from the Fermi velocity being compensated by other contributions such as electrostatics and interactions.Comment: 23 pages 4 fi

    Carrier Frequency Estimation of MPSK Modulated Signals

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    In this paper we concentrate on MPSK carrier frequency estmation based on random data modulation. We present a fast, open-loop frequency estimation and tracking techinque, which combines a feedforward estimator stuctureand a recursive least square (RLS) predictor. It is suitable for the frequency estimation and large frequency acquisition and tracking required of burst mode satellite modems operating under the condition of low SNR and large burst-to-burst frequency offset. The performance of the estimator is analyzed in detail and simulation results are shown. Finally, the non-linear impact of data modulation removal methods is discussed. The estimator we derived is easily implemented with digital hardware. This paper has been submitted to the 1999 International Conferenceon Communications, June 6-10, 1999, Vancouver, Canada</I

    Placebo devices as effective control methods in acupuncture clinical trials : a systematic review

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    While the use of acupuncture has been recognised by the World Health Organisation, its efficacy for many of the common clinical conditions is still undergoing validation through randomised controlled trials (RCTs). A credible placebo control for such RCTs to enable meaningful evaluation of its efficacy is to be established. While several non-penetrating acupuncture placebo devices, namely the Streitberger, the Park and the Takakura Devices, have been developed and used in RCTs, their suitability as inert placebo controls needs to be rigorously determined. This article systematically reviews these devices as placebo interventions. Electronic searches were conducted on four English and two Chinese databases from their inceptions to July 2014; hand searches of relevant references were also conducted. RCTs, in English or Chinese language, comparing acupuncture with one of the aforementioned devices as the control intervention on human participants with any clinical condition and evaluating clinically related outcomes were included. Thirty-six studies were included for qualitative analysis while 14 were in the meta-analysis. The meta-analysis does not support the notion of either the Streitberger or the Park Device being inert control interventions while none of the studies involving the Takakura Device was included in the meta-analysis. Sixteen studies reported the occurrence of adverse events, with no significant difference between verum and placebo acupuncture. Author-reported blinding credibility showed that participant blinding was successful in most cases; however, when blinding index was calculated, only one study, which utilised the Park Device, seemed to have an ideal blinding scenario. Although the blinding index could not be calculated for the Takakura Device, it was the only device reported to enable practitioner blinding. There are limitations with each of the placebo devices and more rigorous studies are needed to further evaluate their effects and blinding credibility
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