1,885 research outputs found
Chemical pre-processing of cluster galaxies over the past 10 billion years in the IllustrisTNG simulations
We use the IllustrisTNG simulations to investigate the evolution of the
mass-metallicity relation (MZR) for star-forming cluster galaxies as a function
of the formation history of their cluster host. The simulations predict an
enhancement in the gas-phase metallicities of star-forming cluster galaxies
(10^9< M_star<10^10 M_sun) at z<1.0 in comparisons to field galaxies. This is
qualitatively consistent with observations. We find that the metallicity
enhancement of cluster galaxies appears prior to their infall into the central
cluster potential, indicating for the first time a systematic "chemical
pre-processing" signature for {\it infalling} cluster galaxies. Namely,
galaxies which will fall into a cluster by z=0 show a ~0.05 dex enhancement in
the MZR compared to field galaxies at z<0.5. Based on the inflow rate of gas
into cluster galaxies and its metallicity, we identify that the accretion of
pre-enriched gas is the key driver of the chemical evolution of such galaxies,
particularly in the stellar mass range (10^9< M_star<10^10 M_sun). We see
signatures of an environmental dependence of the ambient/inflowing gas
metallicity which extends well outside the nominal virial radius of clusters.
Our results motivate future observations looking for pre-enrichment signatures
in dense environments.Comment: 5 pages, 4 figures, accepted for publication in MNRAS Letter
Contact force sensing in ablation of ventricular arrhythmias using a 56-hole open-irrigation catheter: a propensity-matched analysis.
PURPOSE: The effect of adding contact force (CF) sensing to 56-hole tip irrigation in ventricular arrhythmia (VA) ablation has not been previously studied. We aimed to compare outcomes with and without CF sensing in VA ablation using a 56-hole radiofrequency (RF) catheter. METHODS: A total of 164 patients who underwent first-time VA ablation using Thermocool SmartTouch Surround Flow (TC-STSF) catheter (Biosense-Webster, Diamond Bar, CA, USA) were propensity-matched in a 1:1 fashion to 164 patients who had first-time ablation using Thermocool Surround Flow (TC-SF) catheter. Patients were matched for age, gender, cardiac aetiology, ejection fraction and approach. Acute success, complications and long-term follow-up were compared. RESULTS: There was no difference between procedures utilising either TC-SF or TC-STSF in acute success (TC-SF: 134/164 (82%), TC-STSF: 141/164 (86%), p = 0.3), complications (TC-SF: 11/164 (6.7%), TC-STSF: 11/164 (6.7%), p = 1.0) or VA-free survival (TC-SF: mean arrhythmia-free survival time = 5.9 years, 95% CI = 5.4-6.4, TC-STSF: mean = 3.2 years, 95% CI = 3-3.5, log-rank p = 0.74). Fluoroscopy time was longer in normal hearts with TC-SF (19 min, IQR: 14-30) than TC-STSF (14 min, IQR: 8-25; p = 0.04). CONCLUSION: Both TC-SF and TC-STSF catheters are safe and effective in treating VAs. The use of CF sensing catheters did not improve safety or acute and long-term outcomes, but reduced fluoroscopy time in normal heart VA
Clusters at Half Hubble Time: Galaxy Structure and Colors in RXJ0152.7-1357 and MS1054-03
We study the photometric and structural properties of spectroscopically
confirmed members in the two massive X-ray--selected z=0.83 galaxy clusters
MS1054-03 and RXJ0152-1357 using three-band mosaic imaging with the Hubble
Space Telescope Advanced Camera for Surveys. The samples include 105 and 140
members of MS1054-03 and RXJ0152-1357, respectively, with ACS F775W magnitude <
24.0. We develop a promising new structural classification method, based on a
combination of the best-fit Sersic indices and the normalized root-mean-square
residuals from the fits; the resulting classes agree well with the visual ones,
but are less affected by galaxy orientation. We examine the color--magnitude
relations in detail and find that the color residuals correlate with the local
mass density measured from our weak lensing maps; we identify a threshold
density of , in units of the critical density, above which
the star formation appears to cease. For RXJ0152-1357, we also find a trend in
the color residuals with velocity, resulting from an offset of about 980 km/s
in the mean redshifts of the early- and late-type galaxies. Analysis of the
color--color diagrams indicates that a range of star formation time-scales are
needed to reproduce the loci of the galaxy colors. We also identify some
cluster galaxies whose colors can only be explained by large amounts, mag, of internal dust extinction. [Abstract shortened]Comment: 30 pages, emulateapj format; 23 figures, many in color. Accepted by
ApJ; scheduled for the 10 June 2006 issue. Some figures degraded; for a
higher resolution version, see: http://astro.wsu.edu/blakeslee/z1clusters
Near infrared spectroscopy and star-formation histories of 3<z<4 quiescent galaxies
We present Keck-MOSFIRE H and K spectra for a sample of 24 candidate
quiescent galaxies (QGs) at 3<z<4, identified from UVJ colors and photometric
redshifts in the ZFOURGE and 3DHST surveys. We obtain spectroscopic redshifts
for half of the sample, using absorption or emission lines, and confirm the
high accuracy of the photometric redshifts with a median error of 1.2%. Two
galaxies turn out to be dusty objects at lower redshifts (z<2.5), and are the
only two detected in the sub-mm with ALMA. High equivalent-width [OIII] was
observed in two galaxies, contributing up to 30% of the K-band flux and
mimicking the colors of an old stellar population. This implies a failure rate
of only 20% for the UVJ selection at these redshifts. Balmer absorption was
identified in 4 of the brighest galaxies, confirming the absence of OB stars.
Modeling all QGs with a wide range of star-formation histories, we find sSFR a
factor of 10 below the main sequence (MS) for all but one galaxy, and less than
0.01 Gyr for half of the sample. This is consistent with the H
and [OII] luminosities, and the ALMA non-detections. We then find that these
QGs have quenched on average 300 Myr before observation, between z=3.5 and 5,
and that they formed at z~5.5 with a mean SFR~300 Msun/yr. Considering an
alternative selection of QGs based solely on the sSFR from SED modeling, we
find that galaxies a factor 10 below the MS are 40% more numerous than
UVJ-quiescent galaxies, implying that the UVJ selection is pure but incomplete.
Current models fail at reproducing our observations and underestimate either
the number density of QGs by more than an order of magnitude or the duration of
their quiescence by a factor two. Overall, these results confirm the existence
of an unexpected population of QGs at z>3, and offer the first insights on
their formation history. [abridged]Comment: 30 pages (+ appendix), 18 figures, accepted for publication in A&
Resolved velocity profiles of galactic winds at Cosmic Noon
We study the kinematics of the interstellar medium (ISM) viewed "down the
barrel" in 20 gravitationally lensed galaxies during Cosmic Noon (). We use moderate-resolution spectra () from Keck/ESI and
Magellan/MagE to spectrally resolve the ISM absorption in these galaxies into
10 independent elements and use double Gaussian fits to quantify the
velocity structure of the gas. We find that the bulk motion of gas in this
galaxy sample is outflowing, with average velocity centroid
\left=-141 kms ( kms scatter)
measured with respect to the systemic redshift. 16 out of the 20 galaxies
exhibit a clear positive skewness, with a blueshifted tail extending to kms. We examine scaling relations in outflow velocities with
galaxy stellar mass and star formation rate (SFR), finding correlations
consistent with a momentum-driven wind scenario. Our measured outflow
velocities are also comparable to those reported for FIRE-2 and TNG50
cosmological simulations at similar redshift and galaxy properties. We also
consider implications for interpreting results from lower-resolution spectra.
We demonstrate that while velocity centroids are accurately recovered, the
skewness, velocity width, and probes of high velocity gas (e.g., ) are
subject to large scatter and biases at lower resolution. We find that
is required for accurate results for the gas kinematics of our
sample. This work represents the largest available sample of well-resolved
outflow velocity structure at , and highlights the need for good spectral
resolution to recover accurate properties.Comment: 42 pages, 37 figures (including appendix), Accepted for publication,
Ap
Preconditioning of the YSZ-NiO Fuel Cell Anode in Hydrogenous Atmospheres Containing Water Vapor
BAIKAL experiment: status report
We review the present status of the Baikal Neutrino Project and present the
results obtained with the deep underwater neutrino telescope NT-200.Comment: 4 pages, 3 figures. Presented at TAUP 2001 (7th international
workshop on Topics in Astroparticle and Underground Physics), Sep. 2001,
Laboratori Nazionali del Gran Sasso, Assergi, Ital
Long-range transfer of electron-phonon coupling in oxide superlattices
The electron-phonon interaction is of central importance for the electrical
and thermal properties of solids, and its influence on superconductivity,
colossal magnetoresistance, and other many-body phenomena in
correlated-electron materials is currently the subject of intense research.
However, the non-local nature of the interactions between valence electrons and
lattice ions, often compounded by a plethora of vibrational modes, present
formidable challenges for attempts to experimentally control and theoretically
describe the physical properties of complex materials. Here we report a Raman
scattering study of the lattice dynamics in superlattices of the
high-temperature superconductor and the
colossal-magnetoresistance compound that suggests
a new approach to this problem. We find that a rotational mode of the MnO
octahedra in experiences pronounced
superconductivity-induced lineshape anomalies, which scale linearly with the
thickness of the layers over a remarkably long range of
several tens of nanometers. The transfer of the electron-phonon coupling
between superlattice layers can be understood as a consequence of long-range
Coulomb forces in conjunction with an orbital reconstruction at the interface.
The superlattice geometry thus provides new opportunities for controlled
modification of the electron-phonon interaction in complex materials.Comment: 13 pages, 4 figures. Revised version to be published in Nature
Material
Maternal but Not Paternal Association of Ambulatory Blood Pressure With Albumin Excretion in Young Offspring With Type 1 Diabetes
OBJECTIVE: Familial predisposition to hypertension has been associated with the development of diabetic nephropathy in adults, but there are limited data in adolescents. Our aim was to assess whether parental ambulatory blood pressure (ABP) was associated with ABP and albumin excretion in young offspring with type 1 diabetes. RESEARCH DESIGN AND METHODS: Twenty-four-hour ABP monitoring was performed in 509 young offspring (mean +/- SD age 15.8 +/- 2.3 years) with type 1 diabetes, 311 fathers, and 444 mothers. Systolic (SBP) and diastolic blood pressure (DBP) measurements during 24 h, daytime, and nighttime were calculated. Three early morning urinary albumin-to-creatinine ratios (ACRs), A1C, and anthropometric parameters were available for the offspring. RESULTS: All paternal ABP parameters, except for nighttime SBP, were independently related to the offspring's ABP (24-h SBP beta = 0.18, 24-h DBP beta = 0.22, daytime SBP beta = 0.25, daytime DBP beta = 0.23, and nighttime DBP beta = 0.18; all P < 0.01). Maternal 24-h DBP (beta = 0.19, P = 0.004), daytime DBP (beta = 0.09, P = 0.04), and nighttime SBP (beta = 0.24 P = 0.001) were related to the corresponding ABP parameter in the offspring. Significant associations were found between the offspring's logACR and maternal ABP. The association with 24-h DBP (beta = 0.16, P = 0.02), daytime DBP (beta = 0.16 P = 0.02), and nighttime DBP (beta = 0.15 P = 0.03) persisted even after adjustment for the offspring's ABP. Mothers of offspring with microalbuminuria had higher ABP than mothers of offspring without microalbuminuria (all P < 0.05). CONCLUSIONS: In this cohort, parental ABP significantly influenced offspring blood pressure, therefore confirming familial influences on this trait. In addition, maternal ABP, particularly DBP, was closely related to ACR in the offspring, suggesting a dominant effect of maternal genes or an effect of the intrauterine environment on microalbuminuria risk
Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions
Background
Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals.
Results
Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall.
Conclusions
The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions
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