82 research outputs found
Noise-induced stabilization of dynamical states in a non-Markovian system
A Josephson junction subject to an external RF excitation may experience the
inverse AC Josephson effect, where the phase across the junction locks to the
drive. The resulting ``Shapiro steps'' of quantized voltage are currently
utilized in primary voltage standards. The effect has also been a key technique
in the search for topological superconductivity. Here, we study a particularly
interesting regime in which the zero voltage state becomes unstable at zero DC
bias, and the junction spontaneously develops the first Shapiro step with a
voltage . The switching time between the and states ranges from milliseconds to hours.
Most interestingly, we find a surprising regime with a non-monotonic
temperature dependence, in which the switching time demonstrates a pronounced
minimum at intermediate temperatures. Tuning of the measurement parameters is
also shown to give rise to a tristable switching behavior, showcasing the
potential for further experiments in stochastic physics and quantum
thermodynamics
The COSMOS-WIRCam near-infrared imaging survey: I: BzK selected passive and star forming galaxy candidates at z>1.4
(abridged) We present a new near-infrared survey covering the 2 deg sq COSMOS
field. Combining our survey with Subaru B and z images we construct a deep,
wide-field optical-infrared catalogue. At Ks<23 (AB magnitudes) our survey
completeness is greater than 90% and 70% for stars and galaxies respectively
and contains 143,466 galaxies and 13,254 stars. At z~2 our catalogues contain
3931 quiescent and 25,757 star-forming BzK-selected galaxies representing the
largest and most secure sample of these objects to date. Our counts of
quiescent galaxies turns over at Ks~22 an effect which we demonstrate cannot be
due to sample incompleteness. In our survey both the number of faint and bright
quiescent objects exceeds the predictions of a semi-analytic galaxy formation
model, indicating potentially the need for further refinements in the amount of
merging and AGN feedback at z~2 in these models. We measure the angular
correlation function for each sample and find that at small scales the
correlation function for passive BzK galaxies exceeds the clustering of dark
matter. We use 30-band photometric redshifts to derive the spatial correlation
length and the redshift distributions for each object class. At Ks<22 we find
r_0^{\gamma/1.8}=7.0 +/-0.5h^{-1} Mpc for the passive BzK candidates and
4.7+/-0.8h^{-1} Mpc for the star-forming BzK galaxies. Our pBzK galaxies have
an average photometric redshift of z_p~1.4, in approximate agreement with the
limited spectroscopic information currently available. The stacked Ks image
will be made publicly available from IRSA.Comment: Accepted for publication in Astrophysical Journal. 17 pages, 17
figures, minor revisions to match published version available at
http://adsabs.harvard.edu/abs/2010ApJ...708..202
Spectroscopy of luminous z>7 galaxy candidates and sources of contamination in z>7 galaxy searches
We present three bright z+ dropout candidates selected from deep
Near-Infrared (NIR) imaging of the COSMOS 2 square degree field. All three
objects match the 0.8-8um colors of other published z>7 candidates but are
three magnitudes brighter, facilitating further study. Deep spectroscopy of two
of the candidates covering 0.64-1.02um with Keck-DEIMOS and all three covering
0.94-1.10um and 1.52-1.80um with Keck-NIRSPEC detects weak spectral features
tentatively identified as Ly-alpha at z=6.95 and z=7.69 in two of the objects.
The third object is placed at z~1.6 based on a 24um and weak optical detection.
A comparison with the spectral energy distributions of known z<7 galaxies,
including objects with strong spectral lines, large extinction, and large
systematic uncertainties in the photometry yields no objects with similar
colors. However, the lambda>1um properties of all three objects can be matched
to optically detected sources with photometric redshifts at z~1.8, so the
non-detection in the i+ and z+ bands are the primary factors which favors a z>7
solution. If any of these objects are at z~7 the bright end of the luminosity
function is significantly higher at z>7 than suggested by previous studies, but
consistent within the statistical uncertainty and the dark matter halo
distribution. If these objects are at low redshift, the Lyman-Break selection
must be contaminated by a previously unknown population of low redshift objects
with very strong breaks in their broad band spectral energy distributions and
blue NIR colors. The implications of this result on luminosity function
evolution at high redshift is discussed. We show that the primary limitation of
z>7 galaxy searches with broad filters is the depth of the available optical
data.Comment: 15 Pages, 15 figures, accepted to Ap
THE HUPO Human Plasma Proteome Project
The Human Proteomics Organization (HUPO) Human Plasma Proteome Project (PPP) is a prominent example of the inherently collaborative nature of the overall community effort to characterize the proteome of humans in health and disease. The PPP Pilot Phase, called “Exploring the Human Plasma Proteome”, engaged 55 laboratories, four technical committees, and vendors and sponsors on an international scale. Among other outcomes, the PPP generated a Core Dataset of 3020 proteins identified with two or more peptides, fully accessible at EBI/PRIDE, ISB/PeptideAtlas, and University of Michigan websites, a rich resource for follow-on analyses. The PPP provided extensive annotation, correlation of number of peptides with protein concentrations measured by immunoassay, an algorithm for choice of a representative protein for multiple proteins matching a given peptide, and independent analyses from the raw spectra. The next phase of the PPP will emphasize standardized procedures for specimen handling, potent new technology platforms for discovery and for targeted proteomics, and robust informatics efforts, including comparative analyses of other biofluids.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56177/1/769_ftp.pd
Spectroscopic Confirmation Of An Extreme Starburst At Redshift 4.547
We report the spectroscopic confirmation of a sub-mm galaxy (SMG) at z=4.547
with an estimated L_IR=0.5-2.0x10^13 L_sun. The spectra, mid-IR, and X-ray
properties indicate the bolometric luminosity is dominated by star formation at
a rate of >1000M_sun per yr. Multiple, spatially separated components are
visible in the Ly-Alpha line with an observed velocity difference of up to 380
km/sec and the object morphology indicates a merger. The best fit spectral
energy distribution and spectral line indicators suggest the object is 2-8 Myr
old and contains >10^10 M_sun of stellar mass. This object is a likely
progenitor for the massive early type systems seen at z~2.Comment: 4 pages, 4 figures, accepted to ApJ Letter
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Climate and more sustainable cities: climate information for improved planning and management of cities (producers/capabilities perspective)
In the last two decades substantial advances have been made in the understanding of the scientific basis of urban climates. These are reviewed here with attention to sustainability of cities, applications that use climate information, and scientific understanding in relation to measurements and modelling. Consideration is given from street (micro) scale to neighbourhood (local) to city and region (meso) scale. Those areas where improvements are needed in the next decade to ensure more sustainable cities are identified. High-priority recommendations are made in the following six strategic areas: observations, data, understanding, modelling, tools and education. These include the need for more operational urban measurement stations and networks; for an international data archive to aid translation of research findings into design tools, along with guidelines for different climate zones and land uses; to develop methods to analyse atmospheric data measured above complex urban surfaces; to improve short-range, high-resolution numerical prediction of weather, air quality and chemical dispersion through improved modelling of the biogeophysical features of the urban land surface; to improve education about urban meteorology; and to encourage communication across scientific disciplines at a range of spatial and temporal scales
Pre-treatment and extraction techniques for recovery of added value compounds from wastes throughout the agri-food chain
The enormous quantity of food wastes discarded annually force to look for alternatives for this interesting feedstock. Thus, food bio-waste valorisation is one of the imperatives of the nowadays society. This review is the most comprehensive overview of currently existing technologies and processes in this field. It tackles classical and innovative physical, physico-chemical and chemical methods of food waste pre-treatment and extraction for recovery of added value compounds and detection by modern technologies and are an outcome of the COST Action EUBIS, TD1203 Food Waste Valorisation for Sustainable Chemicals, Materials and Fuels
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