2,293 research outputs found
Scalable Production of Ambient Stable Hybrid Bismuth-based Materials: AACVD of Phenethylammonium Bismuth Iodide Films
Large homogeneous and adherent coatings of phenethylammonium bismuth iodide were produced using the cost-effective and scalable aerosol-assisted chemical vapour deposition (AACVD) methodology. The film morphology was found to depend on the deposition conditions and substrates, resulting in different optical properties to those reported from their spin-coated counterparts. Optoelectronic characterization revealed band bending effects occurring between the hybrid material and semiconducting substrates (TiO2 and FTO) due to heterojunction formation, and the optical bandgap of the hybrid material was calculated from UV-visible and PL spectrometry to be 2.05 eV. Maximum values for hydrophobicity and crystallographic preferential orientation were observed for films deposited on FTO/glass substrates, closely followed by values from films deposited on TiO2/glass substrates
Current breeding distributions and predicted range shifts under climate change in two subspecies of Black-tailed Godwits in Asia
Habitat loss and shifts associated with climate change threaten global biodiversity, with impacts likely to be most pronounced at high latitudes. With the disappearance of the tundra breeding habitats, migratory shorebirds that breed at these high latitudes are likely to be even more vulnerable to climate change than those in temperate regions. We examined this idea using new distributional information on two subspecies of Black-tailed Godwits Limosa limosa in Asia: the northerly,bog-breeding L. l. bohaii and the more southerly, steppe-breeding L. l. melanuroides. Based on breeding locations of tagged and molecularly assayed birds, we modelled the current breeding distributions of the two subspecies with species distribution models, tested those models for robustness, and then used them to predict climatically suitable breeding ranges in 2070 according to bioclimatic variables and different climate change scenarios. Our models were robust and showed that climate change is expected to push bohaii into the northern rim of the Eurasian continent. Melanuroides is also expected to shift northward, stopping in the Yablonovyy and Stanovoy Ranges, and breeding elevation is expected to increase. Climatically suitable breeding habitatranges would shrink to 16% and 11% of the currently estimated ranges of bohaii and melanuroides, respectively. Overall, this study provides the first predictions for the future distributions of two little-known Black-tailed Godwit subspecies and highlights the importance of factoring in shifts in bird distribution when designing climate-proof conservation strategies.</p
Formation and evolution of dwarf galaxies in the CDM Universe
We first review the results of the tidal stirring model for the
transformation of gas-rich dwarf irregulars into dwarf spheroidals, which turns
rotationally supported stellar systems into pressure supported ones. We
emphasize the importance of the combined effect of ram pressure stripping and
heating from the cosmic ultraviolet background in removing the gas and
converting the object into a gas poor system as dSphs. We discuss how the
timing of infall of dwarfs into the primary halo determines the final
mass-to-light ratio and star formation history. Secondly we review the results
of recent cosmological simulations of the formation of gas-rich dwarfs. These
simulations are finally capable to produce a realistic object with no bulge, an
exponential profile and a slowly rising rotation curve. The result owes to the
inclusion of an inhomogeneous ISM and a star formation scheme based on regions
having the typical density of molecular cloud complexes. Supernovae-driven
winds become more effective in such mode, driving low angular momentum baryons
outside the virial radius at high redshift and turning the dark matter cusp
into a core. Finally we show the first tidal stirring experiments adopting
dwarfs formed in cosmological simulations as initial conditions. The latter are
gas dominated and have have turbulent thick gaseous and stellar disks disks
that cannot develop strong bars, yet they are efficiently heated into spheroids
by tidal shocks.Comment: 14 pages, 4 Figures, o appear in the proceedings of the CRAL
conference, Lyon, June 2010, "A Universe of Dwarf Galaxies", eds. Philippe
Prugniel & Mina Koleva; EDP Sciences in the European Astronomical Society
Publications Series. (invited talk
A self-validating control system based approach to plant fault detection and diagnosis
An approach is proposed in which fault detection and diagnosis (FDD) tasks are distributed to separate FDD modules associated with each control system located throughout a plant. Intended specifically for those control systems that inherently eliminate steady state error, it is modular, steady state based, requires very little process specific information and therefore should be attractive to control systems implementers who seek economies of scale. The approach is applicable to virtually all types of process plant, whether they are open loop stable or not, have a type or class number of zero or not and so on. Based on qualitative reasoning, the approach is founded on the application of control systems theory to single and cascade control systems with integral action. This results in the derivation of cause-effect knowledge and fault isolation procedures that take into account factors like interactions between control systems, and the availability of non-control-loop-based sensors
Maternal Serum Meteorin Levels and the Risk of Preeclampsia
BACKGROUND: Meteorin (METRN) is a recently described neutrophic factor with angiogenic properties. This is a nested case-control study in a longitudinal cohort study that describes the serum profile of METRN during different periods of gestation in healthy and preeclamptic pregnant women. Moreover, we explore the possible application of METRN as a biomarker. METHODS AND FINDINGS: Serum METRN was measured by ELISA in a longitudinal prospective cohort study in 37 healthy pregnant women, 16 mild preeclamptic women, and 20 healthy non-pregnant women during the menstrual cycle with the aim of assessing serum METRN levels and its correlations with other metabolic parameters. Immunostaining for METRN protein was performed in placenta. A multivariate logistic regression model was proposed and a classifier model was formulated for predicting preeclampsia in early and middle pregnancy. The performance in classification was evaluated using measures such as sensitivity, specificity, and the receiver operating characteristic (ROC) curve. In healthy pregnant women, serum METRN levels were significantly elevated in early pregnancy compared to middle and late pregnancy. METRN levels are significantly lower only in early pregnancy in preeclamptic women when compared to healthy pregnant women. Decision trees that did not include METRN levels in the first trimester had a reduced sensitivity of 56% in the detection of preeclamptic women, compared to a sensitivity of 69% when METRN was included. CONCLUSIONS: The joint measurements of circulating METRN levels in the first trimester and systolic blood pressure and weight in the second trimester significantly increase the probabilities of predicting preeclampsia
The tuning of the energy levels of dibenzosilole copolymers and applications in organic electronics
Simulations of Baryon Acoustic Oscillations II: Covariance matrix of the matter power spectrum
We use 5000 cosmological N-body simulations of 1(Gpc/h)^3 box for the
concordance LCDM model in order to study the sampling variances of nonlinear
matter power spectrum. We show that the non-Gaussian errors can be important
even on large length scales relevant for baryon acoustic oscillations (BAO).
Our findings are (1) the non-Gaussian errors degrade the cumulative
signal-to-noise ratios (S/N) for the power spectrum amplitude by up to a factor
of 2 and 4 for redshifts z=1 and 0, respectively. (2) There is little
information on the power spectrum amplitudes in the quasi-nonlinear regime,
confirming the previous results. (3) The distribution of power spectrum
estimators at BAO scales, among the realizations, is well approximated by a
Gaussian distribution with variance that is given by the diagonal covariance
component. (4) For the redshift-space power spectrum, the degradation in S/N by
non-Gaussian errors is mitigated due to nonlinear redshift distortions. (5) For
an actual galaxy survey, the additional shot noise contamination compromises
the cosmological information inherent in the galaxy power spectrum, but also
mitigates the impact of non-Gaussian errors. The S/N is degraded by up to 30%
for a WFMOS-type survey. (6) The finite survey volume causes additional
non-Gaussian errors via the correlations of long-wavelength fluctuations with
the fluctuations we want to measure, further degrading the S/N values by about
30% even at high redshift z=3.Comment: submitted to ApJ, 14 pages, 12 figures. The full halo model is
included. Minor changes also made, and references adde
Interpreting large-scale redshift-space distortion measurements
The simplest theory describing large-scale redshift-space distortions (RSD),
based on linear theory and distant galaxies, depends on the growth of
cosmological structure, suggesting that strong tests of General Relativity can
be constructed from galaxy surveys. As data sets become larger and the expected
constraints more precise, the extent to which the RSD follow the simple theory
needs to be assessed in order that we do not introduce systematic errors into
the tests by introducing inaccurate simplifying assumptions. We study the
impact of the sample geometry, non-linear processes, and biases induced by our
lack of understanding of the radial galaxy distribution on RSD measurements.
Using LasDamas simulations of the Sloan Digital Sky Survey II (SDSS-II)
Luminous Red Galaxy (LRG) data, these effects are shown to be important at the
level of 20 per cent. Including them, we can accurately model the recovered
clustering in these mock catalogues on scales 30 -- 200 Mpc/h. Applying this
analysis to robustly measure parameters describing the growth history of the
Universe from the SDSS-II data, gives
and
when no prior is imposed on the
growth-rate, and the background geometry is assumed to follow a CDM
model with the WMAP + SNIa priors. The standard WMAP constrained CDM
model with General Relativity predicts
and
, which is fully consistent with
these measurements.Comment: 20 pages, 17 figures, 1 tabl
The PEP survey: clustering of infrared-selected galaxies and structure formation at z~2 in the GOODS South
ABRIDGED-This paper presents the first direct estimate of the 3D clustering
properties of far-infrared sources up to z~3. This has been possible thanks to
the Pacs Evolutionary Probe (PEP) survey of the GOODS South field performed
with the PACS instrument onboard the Herschel Satellite. An analysis of the
two-point correlation function over the whole redshift range spanned by the
data reports for the correlation length, r_0~6.3 Mpc and r_0~6.7 Mpc,
respectively at 100um and 160um, corresponding to dark matter halo masses
M>~10^{12.4} M_sun. Objects at z~2 instead seem to be more strongly clustered,
with r_0~19 Mpc and r_0~17 Mpc in the two considered PACS channels. This
dramatic increase of the correlation length between z~1 and z~2 is connected
with the presence of a wide, M>~10^{14} M_sun, filamentary structure which
includes more than 50% of the sources detected at z~2. An investigation of the
properties of such sources indicates the possibility for boosted star-forming
activity in those which reside within the overdense environment with respect of
more isolated galaxies found in the same redshift range. Lastly, we also
present our results on the evolution of the relationship between luminous and
dark matter in star-forming galaxies between z~1 and z~2. We find that the
increase of (average) stellar mass in galaxies between z~1 and z~2 is
about a factor 10 lower than that of the dark matter haloes hosting such
objects ([z~1]/[z~2] ~ 0.4 vs M_{halo}[z~1]/M_{halo}[z~2] ~ 0.04). Our
findings agree with the evolutionary picture of downsizing whereby massive
galaxies at z~2 were more actively forming stars than their z~1 counterparts,
while at the same time contained a lower fraction of their mass in the form of
luminous matter.Comment: 14 pages, 8 figures, MNRAS accepte
Water-splitting electrocatalysis in acid conditions using ruthenate-iridate pyrochlores
The pyrochlore solid solution (Na0.33Ce0.67)(2)-(Ir1-xRux)(2)O-7 (0<x<1), containing B-site Ru-IV and Ir-IV is prepared by hydrothermal synthesis and used as a catalyst layer for electrochemical oxygen evolution from water at pH<7. The materials have atomically mixed Ru and Ir and their nanocrystalline form allows effective fabrication of electrode coatings with improved charge densities over a typical (Ru, Ir)O-2 catalyst. An in situ study of the catalyst layers using XANES spectroscopy at the Ir L-III and Ru K edges shows that both Ru and Ir participate in redox chemistry at oxygen evolution conditions and that Ru is more active than Ir, being oxidized by almost one oxidation state at maximum applied potential, with no evidence for ruthenate or iridate in + 6 or higher oxidation states
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