4,823 research outputs found
Coulomb Ordering in Anderson-Localized Electron Systems
We consider an electron system under conditions of strong Anderson
localization, taking into account interelectron long-range Coulomb repulsion.
We have established that with the electron density going to zero the Coulomb
interaction brings the arrangement of the Anderson localized electrons closer
and closer to an ideal (Wigner) crystal lattice, provided the temperature is
sufficiently low and the dimension of the system is > 1. The ordering occurs
despite the fact that a random spread of the energy levels of the localized
one-electron states, exceeding the mean Coulomb energy per electron, renders it
impossible the electrons to be self-localized due to their mutual Coulomb
repulsion This differs principally the Coulomb ordered Anderson localized
electron system (COALES) from Wigner crystal, Wigner glass, and any other
ordered electron or hole system that results from the Coulomb self-localization
of electrons/holes. The residual disorder inherent to COALES is found to bring
about a multi-valley ground-state degeneration akin to that in spin glass. With
the electron density increasing, COALES is revealed to turn into Wigner glass
or a glassy state of a Fermi-glass type depending on the width of the random
spread of the electron levels.Comment: 4 pages, LaTeX 2.09, To appear in Phys.Rev B Rapid Communications,
The abstract and the Introduction have been written anew to stress a
principal difference between a new macroscopical state predicted in the paper
and Wigner crystal or Wigner glass, some notations have been change
Antibody and B cell responses to Plasmodium sporozoites
Antibodies are capable of blocking infection of the liver by Plasmodium sporozoites. Accordingly the induction of anti-sporozoite antibodies is a major aim of various vaccine approaches to malaria. In recent years our knowledge of the specificity and quantities of antibodies required for protection has been greatly expanded by clinical trials of various whole sporozoite and subunit vaccines. Moreover, the development of humanized mouse models and transgenic parasites have also aided our ability to assess the specificity of antibodies and their ability to block infection. Nonetheless, considerable gaps remain in our knowledge - in particular in understanding what antigens are recognized by infection blocking antibodies and in knowing how we can induce robust, long-lived antibody responses. Maintaining high levels of circulating antibodies is likely to be of primary importance, as antibodies must block infection in the short time it takes for sporozoites to reach the liver from the skin. It is clear that a better understanding of the development of protective B cell-mediated immunity will aid the development and refinement of malaria vaccines.The authors acknowledge the support of the Australian National
University and Perpetual Foundation for research in the Cockburn
laboratory
The Context of Sexual Risk among African-American Female College Students
Objective: To assess the sexually transmitted infection (STI) awareness, sexual risk behaviors, and related contextual factors of African-American female college students.
Participants: Eighty-nine African-American first year female students attending a majority public four-year college in the southern U.S. participated in the study in Spring, 2006.
Methods: Participants completed an anonymous self-administered paper-and-pencil survey and received a $15 cash incentive.
Results: Participants were highly knowledgeable and aware about STIs and their consequences. While this awareness translated into low levels of risk for many, still others engaged in behaviors and maintained beliefs that could potentially put them at high risk for contracting STIs.
Conclusions: Given the disproportionate rates of STIs among young African-American females, researchers must not ignore the non-behavioral factors (i.e. beliefs and perceptions) that may influence sexual risk behaviors to help in determining optimal methods for intervention and prevention among young African-American females
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I am here – you are there: let's meet sometime
Holography has a unique ability to record objects, and the volume surrounding them, in such outstanding hi-fidelity that we believe we are seeing those objects, not recordings or facsimiles of them. This provides us with a spatial and temporal transport system, allowing the movement and display of spaces or objects which are not physically 'there'.
This text explores our comfortable assumptions about being in one place and looking into another. It circumnavigates Heidiger's complex observations related to the philosophical aspects of 'being', using, instead, the subliminal simplicity of our own experiences which help us know where we are and where the rest of the world appears to be.
The opportunities for holography to allow objects to be in two places simultaneously is explored, with reference to pioneering artists who have examined, and made visible, some of these opportunities. The holographic 'window' is acknowledged and work by the author using holography and projected light installations, made specifically for the series of Alternative Document exhibitions, is referenced in connection with these observations and the framework of the alternative, ephemeral, document
Holography - a critical debate within contemporary visual culture
Preface: This Special Issue attempts to provide a platform for the critical discussion, reflection and analysis of holography, as a process and methodology within the work of creative practitioners. The Issue examines, through the values and vocabulary of artists and curators, how this medium has developed as a considered practice and where pressure can be placed upon the critical principles of this relatively young medium. The participants published here have taken a risk, not only through the public examination of their development, but also by attempting to contextualise the use and display of holography within a contemporary, cultural framework. I want to thank the contributors of this Special Issue, who share my curiosity towards the critical investigation and contextualisation of our work and ideas in the sphere of creative holography
Fence-sitting and an opportunity to unsettle the settled: placing critical pressure on creative holography
The field of creative holography is not known for its critical introspection [...
The KELT-South Telescope
The Kilodegree Extremely Little Telescope (KELT) project is a survey for new
transiting planets around bright stars. KELT-South is a small-aperture,
wide-field automated telescope located at Sutherland, South Africa. The
telescope surveys a set of 26 degree by 26 degree fields around the southern
sky, and targets stars in the range of 8 < V < 10 mag, searching for transits
by Hot Jupiters. This paper describes the KELT-South system hardware and
software and discusses the quality of the observations. We show that KELT-South
is able to achieve the necessary photometric precision to detect transits of
Hot Jupiters around solar-type main-sequence stars.Comment: 26 pages, 13 figure
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