18,897 research outputs found
Spin-dependent phenomena and device concepts explored in (Ga,Mn)As
Over the past two decades, the research of (Ga,Mn)As has led to a deeper
understanding of relativistic spin-dependent phenomena in magnetic systems. It
has also led to discoveries of new effects and demonstrations of unprecedented
functionalities of experimental spintronic devices with general applicability
to a wide range of materials. In this article we review the basic material
properties that make (Ga,Mn)As a favorable test-bed system for spintronics
research and discuss contributions of (Ga,Mn)As studies in the general context
of the spin-dependent phenomena and device concepts. Special focus is on the
spin-orbit coupling induced effects and the reviewed topics include the
interaction of spin with electrical current, light, and heat.Comment: 47 pages, 41 figure
On a model mechanism for the spatial patterning of teeth primordia in the Alligator
We propose a model mechanism for the initiation and spatial positioning of teeth primordia in the alligator,Alligator mississippiensis. Detailed embryological studies by Westergaard & Ferguson (1986, 1987, 1990) show that jaw growth plays a crucial role in the developmental patterning of the tooth initiation process. Based on biological data we develop a reaction-diffusion mechanism, which crucially includes domain growth. The model can reproduce the spatial pattern development of the first seven teeth primordia in the lower half jaw ofA. mississippiensis. The results for the precise spatio-temporal sequence compare well with detailed developmental experiments
New high-pressure phase and equation of state of Ce2Zr2O8
In this paper we report a new high-pressure rhombohedral phase of Ce2Zr2O8
observed from high-pressure angle-dispersive x-ray diffraction and Raman
spectroscopy studies up to nearly 12 GPa. The ambient-pressure cubic phase of
Ce2Zr2O8 transforms to a rhombohedral structure beyond 5 GPa with a feeble
distortion in the lattice. Pressure evolution of unit-cell volume showed a
change in compressibility above 5 GPa. The unit-cell parameters of the
high-pressure rhombohedral phase at 12.1 GPa are ah = 14.6791(3) {\AA}, ch =
17.9421(5) {\AA}, V = 3348.1(1) {\AA}3. The structure relation between the
parent cubic (P2_13) and rhombohedral (P3_2) phases were obtained by
group-subgroup relations. All the Raman modes of the cubic phase showed linear
evolution with pressure with the hardest one at 197 cm-1. Some Raman modes of
the high-pressure phase have a non-linear evolution with pressure and softening
of one low-frequency mode with pressure is found. The compressibility, equation
of state, and pressure coefficients of Raman modes of Ce2Zr2O8 are also
reported.Comment: 33 pages, 8 figures, 6 table
The Origin of N III λ990 and C III λ977 Emission in AGN Narrow-Line Region Gas
We discuss implications of Hopkins Ultraviolet Telescope (HUT) detections of C III λ977 and N III λ990 emission from the narrow-line region of the Seyfert 2 galaxy NGC 1068. In their discovery paper Kriss et al. showed that the unexpectedly great strength of these lines implies that the emitting gas must be shock-heated if the lines are collisionally excited. Here we investigate other processes which excite these lines in photoionization equilibrium. Recombination, mainly dielectronic, and continuum fluorescence are strong contributors to the line. The resulting intensities are sensitive to the velocity field of the emitting gas and require that the turbulence be of the same order of magnitude as the observed line width. We propose optical observations that will decide whether the gas is collisionally or radiatively heated
Moving beyond the ‘language problem': developing an understanding of the intersections of health, language and immigration status in interpreter-mediated health encounters
Health systems internationally are dealing with greater diversity in patient populations. However the focus on ‘the language problem’ has meant little attention is paid to diversity within and between migrant populations; and how interpreted consultations are influenced by intersecting migratory, ethnicity and sociodemographic variables. Our analysis of the experiences of patients, health care providers and interpreters in Scotland evidences the need to move beyond language, addressing multiple hidden inequalities in health care access and provision that operate in both clinic and, especially, home-based settings. We call for a practice-evidenced research agenda promoting cultural communication across health care and home settings, acknowledging immigration status as a social determinant of health.
Sur le plan international, des systèmes de santé font face à une diversité croissante dans ses populations de patients. Cependant, l’accent sur ‘le problème de langue’ se traduit dans une manque d’attention à la diversité a l’intérieur même et entre des populations des migrants; et la façon par laquelle des variables migratoire, ethnique et sociodémographique influencent elles-mêmes des consultations interprétées. Notre analyse des expériences des patients, des professionnels fournissant de soins de santé et des interprètes offre des preuves du besoin de dépasser le problème de langue. Et en faisant cela, nous adressons des multiples inégalités, souvent cachées dans des contextes de soins de santé, dans les milieux clinique et domicile. Nous proposons un programme de recherche basé sur la pratique, qui favorise la communication culturelle dans des milieux clinique et domicile, et qui reconnait le statut d’immigration comme un déterminant social de la santé
Absolute Frequency Measurements of the Hg^+ and Ca Optical Clock Transitions with a Femtosecond Laser
The frequency comb created by a femtosecond mode-locked laser and a
microstructured fiber is used to phase coherently measure the frequencies of
both the Hg^+ and Ca optical standards with respect to the SI second as
realized at NIST. We find the transition frequencies to be f_Hg=1 064 721 609
899 143(10) Hz and f_Ca=455 986 240 494 158(26) Hz, respectively. In addition
to the unprecedented precision demonstrated here, this work is the precursor to
all-optical atomic clocks based on the Hg^+ and Ca standards. Furthermore, when
combined with previous measurements, we find no time variations of these atomic
frequencies within the uncertainties of |(df_Ca/dt)/f_Ca| < 8 x 10^{-14}
yr^{-1}, and |(df_Hg/dt)/f_Hg|< 30 x 10^{-14} yr^{-1}.Comment: 6 pages, including 4 figures. RevTex 4. Submitted to Phys. Rev. Let
First Detection of the White-Dwarf Cooling Sequence of the Galactic Bulge
We present Hubble Space Telescope data of the low-reddening Sagittarius
window in the Galactic bulge. The Sagittarius Window Eclipsing Extrasolar
Planet Search field (3'x3'), together with three more Advanced Camera for
Surveys and eight Wide Field Camera 3 fields, were observed in the F606W and
F814W filters, approximately every two weeks for two years, with the principal
aim of detecting a hidden population of isolated black holes and neutron stars
through astrometric microlensing. Proper motions were measured with an accuracy
of ~0.1 mas/yr (~4 km/s) at F606W~25.5 mag, and better than ~0.5 mas/yr (20
km/s) at F606W~28 mag, in both axes. Proper-motion measurements allowed us to
separate disk and bulge stars and obtain a clean bulge color-magnitude diagram.
We then identified for the first time a white dwarf (WD) cooling sequence in
the Galactic bulge, together with a dozen candidate extreme horizontal branch
stars. The comparison between theory and observations shows that a substantial
fraction of the WDs (30%) are systematically redder than the cooling tracks for
CO-core H-rich and He-rich envelope WDs. This evidence would suggest the
presence of a significant number of low-mass WDs and WD - main sequence
binaries in the bulge. This hypothesis is further supported by the finding of
two dwarf novae in outburst, two short-period (P < 1 d) ellipsoidal variables,
and a few candidate cataclysmic variables in the same field.Comment: 9 pages, 5 figures, accepted for publication on Ap
Temperature perturbation model of the opto-galvanic effect in CO2-laser discharges
A detailed discharge model of the opto-galvanic effect in molecular laser gas mixtures is developed based on the temperature perturbation or discharge cooling mechanism of Smith and Brooks (1979). Excellent agreement between the model and experimental results in CO2 laser gas mixtures is obtained. The model should be applicable to other molecular systems where the OGE is being used for laser stabilisation and as a spectroscopic tool
Primary Connections: Linking science with literacy Stage 6 research evaluation final report
This report presents findings from the External Independent Evaluation and Research for Primary Connections Stage 6 (2014–2018) conducted by a research team from the University of Technology Sydney (UTS)
The scatter about the "Universal" dwarf spheroidal mass profile: A kinematic study of the M31 satellites, And V and And VI
While the satellites of the Milky Way (MW) have been shown to be largely
consistent in terms of their mass contained within one half--light radius
(M_{half}) with a "Universal" mass profile, a number of M31 satellites are
found to be inconsistent with such relations, and seem kinematically colder in
their central regions than their MW cousins. In this work, we present new
kinematic and updated structural properties for two M31 dSphs, And V and And VI
using data from the Keck Low Resolution Imaging Spectrograph (LRIS) and the
DEep Imaging Multi-Object Spectrograph (DEIMOS) instruments and the Subaru
Suprime-Cam imager. We measure systemic velocities of v_r=-393.1+/-4.2km/s and
-344.8+/-2.5km/s, and dispersions of sigma_v=11.5{+5.3}{-4.4}km/s and
sigma_v=9.4{+3.2}{-2.4}km/s for And V and And VI respectively, meaning these
two objects are consistent with the trends in sigma_v and r_{half} set by their
MW counterparts. We also investigate the nature of this scatter about the MW
dSph mass profiles for the "Classical" (i.e. M_V<-8) MW and M31 dSphs. When
comparing both the "classical" MW and M31 dSphs to the best--fit mass profiles
in the size--velocity dispersion plane, we find general scatter in both the
positive (i.e. hotter) and negative (i.e. colder) directions from these
profiles. However, barring one exception (CVnI) only the M31 dSphs are found to
scatter towards a colder regime, and, excepting the And I dSph, only MW objects
scatter to hotter dispersions. We also note that the scatter for the combined
population is greater than expected from measurement errors alone. We assess
this divide in the context of the differing disc-to-halo mass (i.e. stars and
baryons to total virial mass) ratios of the two hosts and argue that the
underlying mass profiles for dSphs differ from galaxy to galaxy, and are
modified by the baryonic component of the host.Comment: 15 pages, 8 figures. Small modifications made for referee report.
Accepted for publication in MNRAS (29/06/2011
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