437 research outputs found
Build it and Will They Come?: Participatory Digital Archives, Hesitant Users, and the Emerging Archival Commons
In the mid-2000s, archivists introduced a range of Web 2.0-based participatory features into digital archives to make them more accessible to patrons. Some archivists hoped the increased accessibility of digital archives would lead to the creation of virtual communities of users that would eventually participate in archival workflows, especially description. Archivistsâ desire culminated in the idea of the archival commons, a network-crowd sourcing model highly dependent on intensive user participation. Users however, only minimally used digital archivesâ participatory features during the mid-â00s. Recent scholarship though, reveals that users have begun to increasingly use the participatory aspects of digital archives, suggesting archivistsâ goal of establishing an archival commons based upon user-participation remains obtainable. This article explains why users underutilized digital archivesâ participatory features during the mid-â00s, analyzes the recent upswing in patronsâ use of such tools, and presents suggestions on how to increase usersâ use of digital archivesâ participatory features
Instrumental and Analytic Methods for Bolometric Polarimetry
We discuss instrumental and analytic methods that have been developed for the
first generation of bolometric cosmic microwave background (CMB) polarimeters.
The design, characterization, and analysis of data obtained using Polarization
Sensitive Bolometers (PSBs) are described in detail. This is followed by a
brief study of the effect of various polarization modulation techniques on the
recovery of sky polarization from scanning polarimeter data. Having been
successfully implemented on the sub-orbital Boomerang experiment, PSBs are
currently operational in two terrestrial CMB polarization experiments (QUaD and
the Robinson Telescope). We investigate two approaches to the analysis of data
from these experiments, using realistic simulations of time ordered data to
illustrate the impact of instrumental effects on the fidelity of the recovered
polarization signal. We find that the analysis of difference time streams takes
full advantage of the high degree of common mode rejection afforded by the PSB
design. In addition to the observational efforts currently underway, this
discussion is directly applicable to the PSBs that constitute the polarized
capability of the Planck HFI instrument.Comment: 23 pages, 11 figures. for submission to A&
The Hanbury Brown and Twiss Experiment with Fermions
We realized an equivalent Hanbury Brown and Twiss experiment for a beam of
electrons in a two dimensional electron gas in the quantum Hall regime. A
metallic split gate serves as a tunable beam splitter which is used to
partition the incident beam into transmitted and reflected partial beams. The
current fluctuations in the reflected and transmitted beam are fully
anticorrelated demonstrating that fermions tend to exclude each other
(anti-bunching). If the occupation probability of the incident beam is lowered
by an additional gate, the anticorrelation is reduced and disappears in the
classical limit of a highly diluted beam
Investigating people: a qualitative analysis of the search behaviours of open-source intelligence analysts
The Internet and the World Wide Web have become integral parts of the lives of many modern individuals, enabling almost instantaneous communication, sharing and broadcasting of thoughts, feelings and opinions. Much of this information is publicly facing, and as such, it can be utilised in a multitude of online investigations, ranging from employee vetting and credit checking to counter-terrorism and fraud prevention/detection. However, the search needs and behaviours of these investigators are not well documented in the literature. In order to address this gap, an in-depth qualitative study was carried out in cooperation with a leading investigation company. The research contribution is an initial identification of Open-Source Intelligence investigator search behaviours, the procedures and practices that they undertake, along with an overview of the difficulties and challenges that they encounter as part of their domain. This lays the foundation for future research in to the varied domain of Open-Source Intelligence gathering
Small size boundary effects on two-pion interferometry
The Bose-Einstein correlations of two identically charged pions are derived
when these particles, the most abundantly produced in relativistic heavy ion
collisions, are confined in finite volumes. Boundary effects on single pion
spectrum are also studied. Numerical results emphasize that conventional
formulation usually adopted to describe two-pion interferometry should not be
used when the source size is small, since this is the most sensitive case to
boundary effects. Specific examples are considered for better illustration.Comment: more discussion on Figure4 and diffuse boundar
Scientists Reflect on Why They Chose to Study Science
A concern commonly raised in literature and in media relates to the declining proportions of students who enter and remain in the âscience pipelineâ, and whether many countries, including Australia and New Zealand, have enough budding scientists to fill research and industry positions in the coming years. In addition, there is concern that insufficient numbers of students continue in science to ensure an informed, scientifically literate citizenry. The aim of the research presented in this paper was to survey current Australian and New Zealand scientists to explore their reasons for choosing to study science. An online survey was conducted via a link to SurveyGizmo. The data presented are from 726 respondents who answered 22 forced-choice items and an open-ended question about the reasons they chose to study science. The quantitative data were analysed using t tests and analyses of variance followed by Duncanâs multiple range tests, and the qualitative data were analysed thematically. The quantitative data showed that the main reasons scientists reported choosing to study science were because they were interested in science and because they were good at science. Secondary school science classes and one particular science teacher also were found to be important factors. Of much less importance were the prestige of science and financial considerations. The qualitative data expanded on these findings and showed that passion for science and/or curiosity about the world were important factors and also highlighted the importance of recreational pursuits, such as camping when a child. In the words of one respondent, âPeople donât go into science for the money and glory. Itâs passion for knowledge and science that always attracted me to the fieldâ
Correlations in atomic systems: Diagnosing coherent superpositions
While investigating quantum correlations in atomic systems, we note that
single measurements contain information about these correlations. Using a
simple model of measurement -- analogous to the one used in quantum optics --
we show how to extract higher order correlation functions from individual
"phtotographs" of the atomic sample. As a possible application we apply the
method to detect a subtle phase coherence in mesoscopic superpostitions.Comment: 4 pages, 2 figures, provisionally accepted to Physical Review Letter
Observation of Antinormally Ordered Hanbury-Brown--Twiss Correlations
We have measured antinormally ordered Hanbury-Brown--Twiss correlations for
coherent states of electromagnetic field by using stimulated parametric
down-conversion process. Photons were detected by stimulated emission, rather
than by absorption, so that the detection responded not only to actual photons
but also to zero-point fluctuations via spontaneous emission. The observed
correlations were distinct from normally ordered ones as they showed excess
positive correlations, i.e., photon bunching effects, which arose from the
thermal nature of zero-point fluctuations.Comment: 5 pages, 3 figures, to appear in Physical Review Letter
An 11.6 Micron Keck Search For Exozodiacal Dust
We have begun an observational program to search nearby stars for dust disks
that are analogous to the disk of zodiacal dust that fills the interior of our
solar system. We imaged six nearby main-sequence stars with the Keck telescope
at 11.6 microns, correcting for atmosphere-induced wavefront aberrations and
deconvolving the point spread function via classical speckle analysis. We
compare our data to a simple model of the zodiacal dust in our own system based
on COBE/DIRBE observations and place upper limits on the density of exozodiacal
dust in these systems.Comment: 10 pages, figure1, figure2, figure3, and figures 4a-
ACBAR: The Arcminute Cosmology Bolometer Array Receiver
We describe the Arcminute Cosmology Bolometer Array Receiver (ACBAR); a
multifrequency millimeter-wave receiver designed for observations of the Cosmic
Microwave Background (CMB) and the Sunyaev-Zel'dovich effect in clusters of
galaxies. The ACBAR focal plane consists of a 16-pixel, background-limited, 240
mK bolometer array that can be configured to observe simultaneously at 150,
220, 280, and 350 GHz. With 4-5' FWHM Gaussian beam sizes and a 3 degree
azimuth chop, ACBAR is sensitive to a wide range of angular scales. ACBAR was
installed on the 2 m Viper telescope at the South Pole in January 2001. We
describe the design of the instrument and its performance during the 2001 and
2002 observing seasons.Comment: 59 pages, 16 figures -- updated to reflect version published in ApJ
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