8,932 research outputs found
Predicting Punitive Attitudes: Racial-Animus towards New Immigrant and Aboriginal Minority Groups as a Mediating Agent upon Public Crime Concerns
In English-speaking Western societyĂąâŹâąs punitive attitudes towards the sentencing of criminal offenders is a well-established phenomenon. Two theoretical models; the Crime-distrust model and Racial-animus model are demonstrated predictors of punitive attitudes. However, little is known about how racial prejudice impacts the association between the publicĂąâŹâąs crime concerns and their demand for harsher sentencing outcomes. The present study utilises online survey data obtained from a convenience sample of 566 Australian residents to examine the Racial-animus model as a mediating agent upon the Crime-distrust model and its relationship with punitive attitudes. A significant indirect effect of racial animus is demonstrated upon the perception of increasing crime rates and public confidence in the court system and punitive attitudes, regardless of whether animus is towards new-immigrants or Indigenous Australians. A significant indirect relationship between fear of crime and the demand for harsher sentencing is only demonstrated through negative perceptions of new immigrants. Results lend support for a mediation model whereby the indirect effect of fear of crime is significant when mediated by negative sentiment towards new-immigrants but not towards Indigenous Australians. Future research using a representative sample of the Australian population is indicated to increase the confidence with which findings are interpreted
Decoherence of Atomic Gases in Largely Detuned Laser Fields
We study theoretically the decoherence of a gas of bosonic atoms induced by
the interaction with a largely detuned laser beam. It is shown that for a
standing laser beam decoherence coincides with the single-particle result. For
a running laser beam many-particle effects lead to significant modifications.Comment: 5 pages, 2 Figures, RevTe
Cluster Populations in A115 and A2283
This paper presents four color narrow-band photometry of clusters A115
() and A2283 () in order to follow the star formation history
of various galaxy types. Although located at similar redshifts, the two
clusters display very different fractions of blue galaxies (i.e. the
Butcher-Oemler effect, for A115, for A2283). A system
of photometric classification is applied to the cluster members that divides
the cluster population into four classes based on their recent levels of star
formation. It is shown that the blue population of each cluster is primarily
composed of normal starforming (SFR < 1 M_{\sun} yrs) galaxies at the
high luminosity end, but with an increasing contribution from a dwarf starburst
population below . This dwarf starburst population appears to be
the same population of low mass galaxies identified in recent HST imaging (Koo
et al 1997), possible progenitors to present-day cluster dwarf ellipticals,
irregulars and BCD's. Deviations in the color-magnitude relationship for the
red galaxies in each cluster suggest that a population of blue S0's is evolving
into present-day S0 colors at this epoch. The radial distribution of the blue
population supports the prediction of galaxy harassment mechanisms for tidally
induced star formation operating on an infalling set of gas-rich galaxies.Comment: 28 pages including 2 tables and 9 figures, AASTeX v4.0. Accepted by
Ap.J. Data, referee report and response are avaliable from
http://zebu.uoregon.edu/~j
Oscillatory Flows Induced by Microorganisms Swimming in Two-dimensions
We present the first time-resolved measurements of the oscillatory velocity
field induced by swimming unicellular microorganisms. Confinement of the green
alga C. reinhardtii in stabilized thin liquid films allows simultaneous
tracking of cells and tracer particles. The measured velocity field reveals
complex time-dependent flow structures, and scales inversely with distance. The
instantaneous mechanical power generated by the cells is measured from the
velocity fields and peaks at 15 fW. The dissipation per cycle is more than four
times what steady swimming would require.Comment: 4 pages, 4 figure
Mach-Zehnder Interferometry in a Strongly Driven Superconducting Qubit
We demonstrate Mach-Zehnder-type interferometry in a superconducting flux
qubit. The qubit is a tunable artificial atom, whose ground and excited states
exhibit an avoided crossing. Strongly driving the qubit with harmonic
excitation sweeps it through the avoided crossing two times per period. As the
induced Landau-Zener transitions act as coherent beamsplitters, the accumulated
phase between transitions, which varies with microwave amplitude, results in
quantum interference fringes for n=1...20 photon transitions. The
generalization of optical Mach-Zehnder interferometry, performed in qubit phase
space, provides an alternative means to manipulate and characterize the qubit
in the strongly-driven regime.Comment: 14 pages, 6 figure
Low-cost interference lithography
The authors report demonstration of a low-cost ( ⌠1000 USD) interference lithography system based on a Lloydâs mirror interferometer that is capable of ⌠300ânm pitch patterning. The components include only a 405ânm GaN diode-laser module, a machinistâs block, a chrome-coated silicon mirror, substrate, and double-sided carbon scanning electron microscopy (SEM) tape. The laser and the machinistâs block were assembled in a linear configuration, and to complete the system, the mirror and substrate were taped to perpendicular surfaces of the machinistâs block. Approximately 50 silicon substrates were prepared, exposed, and developed, after which some were inspected in a SEM. The associated laser spectrum was also measured, enabling calculation of the laserâs fringe visibility as it varied along the substrate surface. To compare the exposed resist pattern to the fringe visibility, the authors measured the first order diffraction efficiency as a function of position along the grating surface. Their measurements indicated that artifacts seen in both the optical spectrum and resulting grating patterns arose from the laser diode source, thus improving the source characteristics will be the topic of future work.Singapore-MIT Alliance for Research and Technolog
Free space-coupled superconducting nanowire single photon detectors for infrared optical communications
This paper describes the construction of a cryostat and an optical system
with a free-space coupling efficiency of 56.5% +/- 3.4% to a superconducting
nanowire single-photon detector (SNSPD) for infrared quantum communication and
spectrum analysis. A 1K pot decreases the base temperature to T = 1.7 K from
the 2.9 K reached by the cold head cooled by a pulse-tube cryocooler. The
minimum spot size coupled to the detector chip was 6.6 +/- 0.11 {\mu}m starting
from a fiber source at wavelength, {\lambda} = 1.55 {\mu}m. We demonstrated
efficient photon counting on a detector with an 8 x 7.3 {\mu}m^2 area. We
measured a dark count rate of 95 +/- 3.35 kcps and a system detection
efficiency of 1.64% +/- 0.13%. We explain the key steps that are required to
further improve the coupling efficiency.Comment: 16 pages, double-space
Creation of Skyrmions in a Spinor Bose-Einstein Condensate
We propose a scheme for the creation of skyrmions (coreless vortices) in a
Bose-Einstein condensate with hyperfine spin F=1. In this scheme, four
traveling-wave laser beams, with Gaussian or Laguerre-Gaussian transverse
profiles, induce Raman transitions with an anomalous dependence on the laser
polarization, thereby generating the optical potential required for producing
skyrmions.Comment: 5 pages, 2 figures, RevTe
On the effects of turbulence on a screw dynamo
In an experiment in the Institute of Continuous Media Mechanics in Perm
(Russia) an non--stationary screw dynamo is intended to be realized with a
helical flow of liquid sodium in a torus. The flow is necessarily turbulent,
that is, may be considered as a mean flow and a superimposed turbulence. In
this paper the induction processes of the turbulence are investigated within
the framework of mean--field electrodynamics. They imply of course a part which
leads to an enhanced dissipation of the mean magnetic field. As a consequence
of the helical mean flow there are also helical structures in the turbulence.
They lead to some kind of --effect, which might basically support the
screw dynamo. The peculiarity of this --effect explains measurements
made at a smaller version of the device envisaged for the dynamo experiment.
The helical structures of the turbulence lead also to other effects, which in
combination with a rotational shear are potentially capable of dynamo action. A
part of them can basically support the screw dynamo. Under the conditions of
the experiment all induction effects of the turbulence prove to be rather weak
in comparison to that of the main flow. Numerical solutions of the mean--field
induction equation show that all the induction effects of the turbulence
together let the screw dynamo threshold slightly, at most by one per cent,
rise. The numerical results give also some insights into the action of the
individual induction effects of the turbulence.Comment: 15 pages, 7 figures, in GAFD prin
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