875 research outputs found
Role of osmotic and hydrostatic pressures in bacteriophage genome ejection
A critical step in the bacteriophage life cycle is genome ejection into host
bacteria. The ejection process for double-stranded DNA phages has been studied
thoroughly \textit{in vitro}, where after triggering with the cellular receptor
the genome ejects into a buffer. The experimental data have been interpreted in
terms of the decrease in free energy of the densely packed DNA associated with
genome ejection. Here we detail a simple model of genome ejection in terms of
the hydrostatic and osmotic pressures inside the phage, a bacterium, and a
buffer solution/culture medium. We argue that the hydrodynamic flow associated
with the water movement from the buffer solution into the phage capsid and
further drainage into the bacterial cytoplasm, driven by the osmotic gradient
between the bacterial cytoplasm and culture medium, provides an alternative
mechanism for phage genome ejection \textit{in vivo}; the mechanism is
perfectly consistent with phage genome ejection \textit{in vitro}.Comment: 5 pages, 2 figures, references update
Local conductance: A means to extract polarization and depolarizing fields near domain walls in ferroelectrics
Creativity and the computer nerd: an exploration of attitudes
This study arises from our concern that many of our best art and design students are failing to make the most of the opportunities provided by IT because of their fear or dislike of computers. This not only deprives them of useful skills, but, even more importantly, deprives many IT based developments of their input. In this paper we investigate the relationship between attitudes to creativity and to computers among students. We quickly discard an approach based on theories of personality types as philosophically and educationally problematic. An approach based on the self-concept of artists and designers, in relation to their own creativity and to their feelings about computers, offers more hope of progress. This means that we do not try to define the attributes of "creative people". Rather, we ask what creativity means to students of art and design and relate these responses to their attitudes to computers. Self-concept depends on how the subjects see themselves within society and culture, and is liable to change as culture changes. One major instrument of cultural change at the present time is the growth of IT itself. We then describe a first attempt at using a psychological method - Kelly's Repertory Grids - to investigate the self-concept of artists and designers. It is hoped to continue with this approach in further studies over the next few years
Influence of charged walls and defects on DC resistivity and dielectric relaxation in Cu-Cl boracite
Electrostatic model of atomic ordering in complex perovskite alloys
We present a simple ionic model which successfully reproduces the various
types of compositional long-range order observed in a large class of complex
insulating perovskite alloys. The model assumes that the driving mechanism
responsible for the ordering is simply the electrostatic interaction between
the different ionic species. A possible new explanation for the anomalous
long-range order observed in some Pb relaxor alloys, involving the proposed
existence of a small amount of Pb^4+ on the B sublattice, is suggested by an
analysis of the model.Comment: 4 pages, two-column style with 1 postscript figure embedded. Uses
REVTEX and epsf macros. Also available at
http://www.physics.rutgers.edu/~dhv/preprints/index.html#lb_orde
Space Images for NASA/JPL
Space Images for NASA/JPL is an Apple iPhone application that allows the general public to access featured images from the Jet Propulsion Laboratory (JPL). A back-end infrastructure stores, tracks, and retrieves space images from the JPL Photojournal Web server, and catalogs the information into a streamlined rating infrastructure
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