3,517 research outputs found
A clinical evaluation of extended wear contact lenses
A clinical evaluation of extended wear contact lense
The Gattini cameras for optical sky brightness measurements at Dome C, Antarctica
The Gattini cameras are two site testing instruments for
the measurement of optical sky brightness, large area cloud cover and auroral detection of the night sky above the high altitude Dome C site in Antarctica. The cameras have been operating since installation in January 2006 and are currently at the end of the first Antarctic winter season. The cameras are transit in nature and are virtually identical both adopting Apogee Alta CCD detectors. By taking frequent images of the night sky we obtain long term cloud cover statistics, measure the sky background intensity as a function of solar and lunar altitude and
phase and directly measure the spatial extent of bright aurora if present and when they occur. The full data set will return in December 2006 however a limited amount of data has been transferred via the Iridium network enabling preliminary data reduction and system evaluation.
An update of the project is presented together with preliminary results from data taken since commencement of the winter season
Sixteen years of Collaborative Learning through Active Sense-making in Physics (CLASP) at UC Davis
This paper describes our large reformed introductory physics course at UC
Davis, which bioscience students have been taking since 1996. The central
feature of this course is a focus on sense-making by the students during the
five hours per week discussion/labs in which the students take part in
activities emphasizing peer-peer discussions, argumentation, and presentations
of ideas. The course differs in many fundamental ways from traditionally taught
introductory physics courses. After discussing the unique features of CLASP and
its implementation at UC Davis, various student outcome measures are presented
showing increased performance by students who took the CLASP course compared to
students who took a traditionally taught introductory physics course. Measures
we use include upper-division GPAs, MCAT scores, FCI gains, and MPEX-II scores.Comment: Also submitted to American Journal of Physic
A Nonword Repetition Task for Speakers with Misarticulations: The Syllable Repetition Task (SRT)
Purpose. Conceptual and methodological confounds occur when non(sense) repetition tasks are administered to speakers who do not have the target speech sounds in their phonetic inventories or who habitually misarticulate targeted speech sounds. We describe a nonword repetition task, the Syllable Repetiton Task (SRT) that eliminates this confound and report findings from three validity studies. Method. Ninety-five preschool children with Speech Delay and 63 with Typical Speech, completed an assessment battery that included the Nonword Repetition Task (NRT: Dollaghan & Campbell, 1998) and the SRT. SRT stimuli include only four of the earliest occurring consonants and one early occurring vowel. Results. Study 1 findings indicated that the SRT eliminated the speech confound in nonword testing with speakers who misarticulate. Study 2 findings indicated that the accuracy of the SRT to identify expressive language impairment was comparable to findings for the NRT. Study 3 findings illustrated the SRT’s potential to interrogate speech processing constraints underlying poor nonword repetition accuracy. Results supported both memorial and auditory-perceptual encoding constraints underlying nonword repetition errors in children with speech-language impairment. Conclusion. The SRT appears to be a psychometrically stable and substantively informative nonword repetition task for emerging genetic and other research with speakers who misarticulate
The PLATO Antarctic site testing observatory
Over a decade of site testing in Antarctica has shown that both South Pole and Dome C are exceptional sites for astronomy, with certain atmospheric conditions superior to those at existing mid-latitude sites. However, the highest point on the Antarctic plateau, Dome A, is expected to experience colder atmospheric temperatures, lower wind speeds, and a turbulent boundary layer that is confined closer to the ground. The Polar Research Institute of China, who were the first to visit the Dome A site in January 2005, plan to establish a permanently manned station there within the next decade. As part of this process they conducted a second expedition to Dome A, arriving via overland traverse in January 2008. This traverse involved the delivery and installation of the PLATeau Observatory (PLATO). PLATO is an automated self-powered astrophysical site testing observatory, developed by the University of New South Wales. A number of international institutions have contributed site testing instruments measuring turbulence, optical sky background, and sub-millimetre transparency. In addition, a set of science instruments are providing wide-field high time resolution optical photometry and terahertz imaging of the Galaxy. We present here an overview of the PLATO system design and instrumentation suite
Neuropsychological constraints to human data production on a global scale
Which are the factors underlying human information production on a global
level? In order to gain an insight into this question we study a corpus of
252-633 Million publicly available data files on the Internet corresponding to
an overall storage volume of 284-675 Terabytes. Analyzing the file size
distribution for several distinct data types we find indications that the
neuropsychological capacity of the human brain to process and record
information may constitute the dominant limiting factor for the overall growth
of globally stored information, with real-world economic constraints having
only a negligible influence. This supposition draws support from the
observation that the files size distributions follow a power law for data
without a time component, like images, and a log-normal distribution for
multimedia files, for which time is a defining qualia.Comment: to be published in: European Physical Journal
Bose-Fermi duality and entanglement entropies
Entanglement (Renyi) entropies of spatial regions are a useful tool for
characterizing the ground states of quantum field theories. In this paper we
investigate the extent to which these are universal quantities for a given
theory, and to which they distinguish different theories, by comparing the
entanglement spectra of the massless Dirac fermion and the compact free boson
in two dimensions. We show that the calculation of Renyi entropies via the
replica trick for any orbifold theory includes a sum over orbifold twists on
all cycles. In a modular-invariant theory of fermions, this amounts to a sum
over spin structures. The result is that the Renyi entropies respect the
standard Bose-Fermi duality. Next, we investigate the entanglement spectrum for
the Dirac fermion without a sum over spin structures, and for the compact boson
at the self-dual radius. These are not equivalent theories; nonetheless, we
find that (1) their second Renyi entropies agree for any number of intervals,
(2) their full entanglement spectra agree for two intervals, and (3) the
spectrum generically disagrees otherwise. These results follow from the
equality of the partition functions of the two theories on any Riemann surface
with imaginary period matrix. We also exhibit a map between the operators of
the theories that preserves scaling dimensions (but not spins), as well as OPEs
and correlators of operators placed on the real line. All of these coincidences
can be traced to the fact that the momentum lattice for the bosonized fermion
is related to that of the self-dual boson by a 45 degree rotation that mixes
left- and right-movers.Comment: 40 pages; v3: improvements to presentation, new section discussing
entanglement negativit
Interleukin 7 from Maternal Milk Crosses the Intestinal Barrier and Modulates T- Cell Development in Offspring
Background
Breastfeeding protects against illnesses and death in hazardous environments, an
effect partly mediated by improved immune function. One hypothesis suggests that
factors within milk supplement the inadequate immune response of the offspring,
but this has not been able to account for a series of observations showing that
factors within maternally derived milk may supplement the development of the
immune system through a direct effect on the primary lymphoid organs. In a
previous human study we reported evidence suggesting a link between IL-7 in
breast milk and the thymic output of infants. Here we report evidence in mice of
direct action of maternally-derived IL-7 on T cell development in the offspring.
Methods and Findings
 We have used recombinant IL-7 labelled with a fluorescent dye to trace the
movement in live mice of IL-7 from the stomach across the gut and into the
lymphoid tissues. To validate the functional ability of maternally derived IL-
7 we cross fostered IL-7 knock-out mice onto normal wild type mothers. Subsets
of thymocytes and populations of peripheral T cells were significantly higher
than those found in knock-out mice receiving milk from IL-7 knock-out mothers.
Conclusions/Significance Our study provides direct evidence that interleukin 7,
a factor which is critical in the development of T lymphocytes, when maternally
derived can transfer across the intestine of the offspring, increase T cell
production in the thymus and support the survival of T cells in the peripheral
secondary lymphoid tissue
Vortex Line Fluctuations in Model High Temperature Superconductors
We carry out Monte Carlo simulations of the uniformly frustrated 3d XY model
as a model for vortex line fluctuations in a high Tc superconductor. A density
of vortex lines of f=1/25 is considered. We find two sharp phase transitions.
The low T phase is an ordered vortex line lattice. The high T normal phase is a
vortex line liquid with much entangling, cutting, and loop excitations. An
intermediate phase is found which is characterized as a vortex line liquid of
disentangled lines. In this phase, the system displays superconducting
properties in the direction parallel to the magnetic field, but normal behavior
in planes perpendicular to the magnetic field.Comment: 38 pages, LaTeX 15 figures (upon request to
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