2,304 research outputs found
The mid-infrared colors of the interstellar medium and extended sources at the Galactic center
A mid-infrared (3.6â8 ÎŒm) survey of the Galactic center has been carried out with the IRAC instrument on the Spitzer Space Telescope. This survey covers the central 2Âș x 1.4Âș (~280 x 200 pc) of the Galaxy. At 3.6 and 4.5 ÎŒm the emission is dominated by stellar sources, the fainter ones merging into an unresolved background. At 5.8 and 8 ÎŒm the stellar sources are fainter, and large-scale diffuse emission from the ISM of the Galaxy's central molecular zone becomes prominent. The survey reveals that the 8-to-5.8 ÎŒm color of the ISM emission is highly uniform across the surveyed region. This uniform color is consistent with a flat extinction law and emission from polycyclic aromatic hydrocarbons (PAHs). Models indicate that this broadband color should not be expected to change if the incident radiation field heating the dust and PAHs is ~10^4 times that of the solar neighborhood. Other regions of very red emission indicate cases where thick dust clouds obscure deeply embedded objects or very early stages of star formation
Entanglement, measurement, and conditional evolution of the Kondo singlet interacting with a mesoscopic detector
We investigate various aspects of the Kondo singlet in a quantum dot (QD)
electrostatically coupled to a mesoscopic detector. The two subsystems are
represented by an entangled state between the Kondo singlet and the
charge-dependent detector state. We show that the phase-coherence of the Kondo
singlet is destroyed in a way that is sensitive to the charge-state information
restored both in the magnitude and in the phase of the scattering coefficients
of the detector. We also introduce the notion of the `conditional evolution' of
the Kondo singlet under projective measurement on the detector. Our study
reveals that the state of the composite system is disentangled upon this
measurement. The Kondo singlet evolves into a particular state with a fixed
number of electrons in the quantum dot. Its relaxation time is shown to be
sensitive only to the QD-charge dependence of the transmission probability in
the detector, which implies that the phase information is erased in this
conditional evolution process. We discuss implications of our observations in
view of the possible experimental realization.Comment: Focus issue on "Interference in Mesoscopic Systems" of New J. Phy
Angular dependent vortex pinning mechanisms in YBCO coated conductors and thin films
We present a comparative study of the angular dependent critical current
density in YBa2Cu3O7 films deposited on IBAD MgO and on single crystal MgO and
SrTiO3 substrates. We identify three angular regimes where pinning is dominated
by different types of correlated and uncorrelated defects. We show that those
regimes are present in all cases, indicating that the pinning mechanisms are
the same, but their extension and characteristics are sample dependent,
reflecting the quantitative differences in texture and defect density. In
particular, the more defective nature of the films on IBAD turns into an
advantage as it results in stronger vortex pinning, demonstrating that the
critical current density of the films on single crystals is not an upper limit
for the performance of the IBAD coated conductors.Comment: 14 pages, 3 figures. Submitted to AP
The influence of protein concentration on key quality attributes of chickpea-based alternatives to cheese
In response to consumer demands, plant protein ingredients are increasingly being used in the formulation of plant-based alternatives to cheese. The aim of this study was to determine the influence of protein concentration on key quality attributes of chickpea-based alternatives to cheese. Moreover, the age-induced changes in such attributes were assessed, with samples analysed after 1 month of storage. After characterisation of the ingredients, the chickpea-based formulations were prepared by blending chickpea flour and protein concentrate in different proportions to obtain four samples of increasing protein content (i.e., 8.68â21.5%). Formulations were developed at pH âŒ4.5, and a moisture content of 50%, with shea butter used to obtain 15% fat content. The differential scanning calorimetry thermograms of the samples showed a main peak around 30 °C, corresponding to transition of the shea butter, and a smaller peak around 70 °C related to starch gelatinisation. Analysis of microstructure showed formation of a protein matrix with more extensive protein structure at high protein concentration. Furthermore, none of the chickpea-based samples melted under the testing conditions and all samples showed increasing values for adhesiveness, springiness and cohesiveness with increasing protein content. However, hardness was the highest for the sample with the lowest protein content, likely due to starch retrogradation. After storage, hardness increased further for all samples. This work improves our understanding of the role of chickpea protein in developing plant-based alternatives to cheese and the challenges therein
Women playwrights in post-apartheid South Africa : Yael Farber, Lara Foot-Newton, and the call for Ubuntu
This chapter explores how these two contemporary South African female playwrights are using specific aesthetics to address legacies of apartheid violence in the post-apartheid context. It analyses Yael Farber's post TRC plays 'A Woman in Waiting' (1999), 'Amajuba' (2002), 'He left Quietly' (2003) and 'Molora' (2007); and Lara Foot-Newton's 'Tshepang: The Third testament' (2003), 'Karoo Moose' (2007) and 'Reach!' (2007)
Being adaptive to pain enhances sham acupuncture analgesia:A crossover healthy human study
We have reported a model that distinguishes pain adaptive individuals (PA) from those who are pain non-adaptive (PNA). The present randomised, cross-over, participant-assessor blinded study aimed to determine the impact of pain adaptability on individualsâ response to real and sham acupuncture. Healthy volunteers (nine PA and 13 PNA) were randomly allocated to receive real and sham acupuncture on the left hand and forearm in two separate acupuncture sessions. Pressure pain thresholds (PPTs) were measured at bilateral forearms and right leg before, immediately after and 20 minutes after the end of acupuncture. Ratings to pinprick and suprathreshold PPT were also recorded. The two groups were comparable in their demographic and baseline data. Analgesia induced by real or sham acupuncture did not differ on any outcome measures. PA responded to acupuncture needling better than PNA, and to sham needling (20% increase in PPT) better than to real acupuncture (7.9%). Those differences were at 20 min after end of acupuncture in the areas distant to the needling sites. PNA reported little changes in PPT. Being adaptive to pain was associated with enhanced distant analgesia in response to sham acupuncture. Our finding might partly explain varied acupuncture analgesia in clinical practice and trials
Detection of large-scale synchrotron radiation from the molecular envelope of the Sgr B cloud complex at the Galactic center
We present highly sensitive measurements taken with MeerKAT at 1280 MHz as
well as archival GBT, MWA and VLA images at 333, 88 and 74 MHz. We report the
detection of synchrotron radio emission from the infrared dark cloud (IRDC)
associated with the halo of the Sgr B complex on a scale of ~60 pc. A strong
spatial correlation between low-frequency radio continuum emission and dense
molecular gas, combined with spectral index measurements, indicates enhanced
synchrotron emission by cosmic-ray electrons. Correlation of the FeI 6.4 keV
Kalpha line and synchrotron emission provides compelling evidence that the low
energy cosmic-ray electrons are responsible for producing the Kalpha line
emission. The observed synchrotron emission within the halo of the Sgr B cloud
complex has mean spectral index alpha -1+/-1 gives the magnetic field strength
~100 muG for cloud densities nH = 10^4-10^5 cm-3 and estimate cosmic-ray
ionization rates between 10^-13 and 10^-14 s^-1. Furthermore, the energy
spectrum of primary cosmic-ray electrons is constrained to be E^-3 +/-1 for
typical energies of few hundred MeV. The extrapolation of this spectrum to
higher energies is consistent with X-ray and gamma-ray emission detected from
this cloud. These measurements have important implications on the role that
high cosmic-ray electron fluxes at the Galactic center play in production of
radio synchrotron emission, the FeI Kalpha line emission at 6.4 keV and ~GeV
gamma-ray emission throughout the central molecular zone (CMZ).Comment: 10 pages, 4 figures, MN (in press
The Mid-Infrared Colors of the ISM and Extended Sources at the Galactic Center
A mid-infrared (3.6-8 um) survey of the Galactic Center has been carried out
with the IRAC instrument on the Spitzer Space Telescope. This survey covers the
central 2x1.4 degree (~280x200 pc) of the Galaxy. At 3.6 and 4.5 um the
emission is dominated by stellar sources, the fainter ones merging into an
unresolved background. At 5.8 and 8 um the stellar sources are fainter, and
large-scale diffuse emission from the ISM of the Galaxy's central molecular
zone becomes prominent. The survey reveals that the 8 to 5.8 um color of the
ISM emission is highly uniform across the surveyed region. This uniform color
is consistent with a flat extinction law and emission from polycyclic aromatic
hydrocarbons (PAHs). Models indicate that this broadband color should not be
expected to change if the incident radiation field heating the dust and PAHs is
<10^4 times that of the solar neighborhood. The few regions with unusually red
emission are areas where the PAHs are underabundant and the radiation field is
locally strong enough to heat large dust grains to produce significant 8 um
emission. These red regions include compact H II regions, Sgr B1, and wider
regions around the Arches and Quintuplet Clusters. In these regions the
radiation field is >10^4 times that of the solar neighborhood. Other regions of
very red emission indicate cases where thick dust clouds obscure deeply
embedded objects or very early stages of star formation.Comment: 37 pages, 15 Postscript figures (low resolution). Accepted for
publication in the Ap
- âŠ