2,207 research outputs found
Mid-Infrared Spectroscopy of Two Lensed Star-forming Galaxies
We present low-resolution, rest-frame ~ 5 - 12 micron Spitzer/IRS spectra of
two lensed z ~ 2 UV-bright star-forming galaxies, SDSS J120602.09+514229.5 and
SDSS J090122.37+181432.3. Using the magnification boost from lensing, we are
able to study the physical properties of these objects in greater detail than
is possible for unlensed systems. In both targets, we detect strong PAH
emission at 6.2, 7.7, and 11.3 microns, indicating the presence of vigorous
star formation. For J1206, we find a steeply rising continuum and significant
[S IV] emission, suggesting that a moderately hard radiation field is powering
continuum emission from small dust grains. The strength of the [S IV] emission
also implies a sub-solar metallicity of ~ 0.5 Z_{Sun}, confirming published
rest-frame optical measurements. In J0901, the PAH lines have large rest-frame
equivalent widths (> 1 micron) and the continuum rises slowly with wavelength,
suggesting that any AGN contribution to L_{IR} is insignificant, in contrast to
the implications of optical emission-line diagnostics. Using [O III] line flux
as a proxy for AGN strength, we estimate that the AGN in J0901 provides only a
small fraction of its mid-infrared continuum flux. By combining the detection
of [Ar II] with an upper limit on [Ar III] emission, we infer a metallicity of
> 1.3 Z_{Sun}. This work highlights the importance of combining rest-frame
optical and mid-IR spectroscopy in order to understand the detailed properties
of star-forming galaxies at high redshift.Comment: 20 pages, 3 figures, 2 tables. ApJ accepte
A Study of Interstellar Gas and Stars in the Gravitationally Lensed Galaxy `The Cosmic Eye' from Rest-Frame Ultraviolet Spectroscopy
We report the results of a study of the rest-frame UV spectrum of the Cosmic
Eye, a luminous Lyman break galaxy at z=3.07331 gravitationally lensed by a
factor of 25. The spectrum, recorded with the ESI spectrograph on the Keck II
telescope, is rich in absorption features from the gas and massive stars in
this galaxy. The interstellar absorption lines are resolved into two components
of approximately equal strength and each spanning several hundred km/s in
velocity. One component has a net blueshift of -70 km/s relative to the stars
and H II regions and presumably arises in a galaxy-scale outflow similar to
those seen in most star-forming galaxies at z = 2-3. The other is more unusual
in showing a mean redshift of +350 km/s relative to the systemic redshift;
possible interpretations include a merging clump, or material ejected by a
previous star formation episode and now falling back onto the galaxy, or more
simply a chance alignment with a foreground galaxy. In the metal absorption
lines, both components only partially cover the OB stars against which they are
being viewed. We tentatively associate the redshifted component with the strong
damped Lyman alpha line, indicative of a column density N(H I) = (3.0 +/- 0.8)
x 10(21) atoms/cm2, and propose that it provides the dust `foreground screen'
responsible for the low ratio of far-infrared to UV luminosities of the Cosmic
Eye. Compared to other well-studied examples of strongly lensed galaxies, we
find that the young stellar population of the Cosmic Eye is essentially
indistinguishable from those of the Cosmic Horseshoe and MS 1512-cB58, while
the interstellar spectra of all three galaxies are markedly different,
attesting to the real complexity of the interplay between starbursts and
ambient interstellar matter in young galaxies (abridged).Comment: 14 pages, 6 Figures, Accepted for publication in Monthly Notices of
the Royal Astronomical Society after minor revision
TGF-beta(2)- and H2O2-Induced Biological Changes in Optic Nerve Head Astrocytes Are Reduced by the Antioxidant Alpha-Lipoic Acid
Background/Aims: The goal of the present study was to determine whether transforming growth factor-beta(2) (TGF-beta(2))- and oxidative stress-induced cellular changes in cultured human optic nerve head (ONH) astrocytes could be reduced by pretreatment with the antioxidant alpha-lipoic acid (LA). Methods: Cultured ONH astrocytes were treated with 1.0 ng/ml TGF-beta(2) for 24 h or 200 mu M hydrogen peroxide (H2O2) for 1 h. Lipid peroxidation was measured by a decrease in cis-pari-naric acid fluorescence. Additionally, cells were pretreated with different concentrations of LA before TGF-beta 2 or H2O2 exposure. Expressions of the heat shock protein (Hsp) alpha B-crystallin and Hsp27, the extracellular matrix (ECM) component fibronectin and the ECM-modulating protein connective tissue growth factor (CTGF) were examined with immunohistochemistry and real-time PCR analysis. Results: Both TGF-beta(2) and H2O2 increased lipid peroxidation. Treatment of astrocytes with TGF-beta(2) and H2O2 upregulated the expression of alpha B-crystallin, Hsp27, fibronectin and CTGF. Pretreatment with different concentrations of LA reduced the TGF-beta(2)- and H2O2-stimulated gene expressions. Conclusion: We showed that TGF-beta(2)- and H2O2-stimulated gene expressions could be prevented by pretreatment with the antioxidant LA in cultured human ONH astrocytes. Therefore, it is tempting to speculate that the use of antioxidants could have protective effects in glaucomatous optic neuropathy. Copyright (C) 2012 S. Karger AG, Base
Preoperative Breast MRI in the Surgical Treatment of Ductal Carcinoma In Situ
n Abstract: Accurate determination of the size or extent of ductal carcinoma in situ (DCIS) by imaging is uncertain, and incomplete resection of tumor results in involved margins in up to 81% of cases. This study examined the accuracy of magnetic resonance imaging (MRI) for assessment of DCIS size, and evaluated the effect of preoperative breast MRI on achievement of tumor-free surgical margins after breast-conserving surgery (BCS). One-hundred and fifty-eight female patients with DCIS were identified from a prospective database: 60 patients (62 cases) had preoperative breast MRI, and 98 patients did not have MRI. The accuracy of tumor size assessed by MRI was determined by comparison with histopathologic size. All patients underwent BCS initially. The rate of involved margins after resection was compared in MRI and no-MRI groups. The overall correlation between MRI size and histopathologic size was high (p < 0.0001). MRI assessment of size was significantly more accurate when DCIS was high grade (p < 0.0001) or intermediate grade (p = 0.005) versus low grade (p = 0.187). The rate of tumor-involved margins was not significantly different in MRI and no-MRI groups (30.7% and 24.7%, respectively; p = 0.414). The rate of mastectomy was significantly higher in the MRI group than the no-MRI group (17.7% versus 4.1%; p = 0.004). These findings indicate that MRI can detect DCIS, especially when lesions are high or intermediate grade, but that MRI does not accurately predict the size of DCIS. In this study, MRI did not improve the surgeon's ability to achieve clear margins following BCS.
The Origin and Contribution of Cancer-Associated Fibroblasts in Colorectal Carcinogenesis
Background & Aims: Cancer-associated fibroblasts (CAFs) play an important role in colorectal cancer (CRC) progression and predict poor prognosis in CRC patients. However, the cellular origins of CAFs remain unknown, making it challenging to therapeutically target these cells. Here, we aimed to identify the origins and contribution of colorectal CAFs associated with poor prognosis. Methods: To elucidate CAF origins, we used a colitis-associated CRC mouse model in 5 different fate-mapping mouse lines with 5-bromodeoxyuridine dosing. RNA sequencing of fluorescence-activated cell sorting–purified CRC CAFs was performed to identify a potential therapeutic target in CAFs. To examine the prognostic significance of the stromal target, CRC patient RNA sequencing data and tissue microarray were used. CRC organoids were injected into the colons of knockout mice to assess the mechanism by which the stromal gene contributes to colorectal tumorigenesis. Results: Our lineage-tracing studies revealed that in CRC, many ACTA2+ CAFs emerge through proliferation from intestinal pericryptal leptin receptor (Lepr)+ cells. These Lepr-lineage CAFs, in turn, express melanoma cell adhesion molecule (MCAM), a CRC stroma-specific marker that we identified with the use of RNA sequencing. High MCAM expression induced by transforming growth factor β was inversely associated with patient survival in human CRC. In mice, stromal Mcam knockout attenuated orthotopically injected colorectal tumoroid growth and improved survival through decreased tumor-associated macrophage recruitment. Mechanistically, fibroblast MCAM interacted with interleukin-1 receptor 1 to augment nuclear factor κB–IL34/CCL8 signaling that promotes macrophage chemotaxis. Conclusions: In colorectal carcinogenesis, pericryptal Lepr-lineage cells proliferate to generate MCAM+ CAFs that shape the tumor-promoting immune microenvironment. Preventing the expansion/differentiation of Lepr-lineage CAFs or inhibiting MCAM activity could be effective therapeutic approaches for CRC
Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS
The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
Posttraumatic Stress Disorder Prevalence and Risk of Recurrence in Acute Coronary Syndrome Patients: A Meta-analytic Review
BACKGROUND:Acute coronary syndromes (ACS; myocardial infarction or unstable angina) can induce posttraumatic stress disorder (PTSD), and ACS-induced PTSD may increase patients' risk for subsequent cardiac events and mortality. OBJECTIVE:To determine the prevalence of PTSD induced by ACS and to quantify the association between ACS-induced PTSD and adverse clinical outcomes using systematic review and meta-analysis. DATA SOURCES:Articles were identified by searching Ovid MEDLINE, PsycINFO, and Scopus, and through manual search of reference lists. METHODOLOGY/PRINCIPAL FINDINGS:Observational cohort studies that assessed PTSD with specific reference to an ACS event at least 1 month prior. We extracted estimates of the prevalence of ACS-induced PTSD and associations with clinical outcomes, as well as study characteristics. We identified 56 potentially relevant articles, 24 of which met our criteria (N = 2383). Meta-analysis yielded an aggregated prevalence estimate of 12% (95% confidence interval [CI], 9%-16%) for clinically significant symptoms of ACS-induced PTSD in a random effects model. Individual study prevalence estimates varied widely (0%-32%), with significant heterogeneity in estimates explained by the use of a screening instrument (prevalence estimate was 16% [95% CI, 13%-20%] in 16 studies) vs a clinical diagnostic interview (prevalence estimate was 4% [95% CI, 3%-5%] in 8 studies). The aggregated point estimate for the magnitude of the relationship between ACS-induced PTSD and clinical outcomes (ie, mortality and/or ACS recurrence) across the 3 studies that met our criteria (N = 609) suggested a doubling of risk (risk ratio, 2.00; 95% CI, 1.69-2.37) in ACS patients with clinically significant PTSD symptoms relative to patients without PTSD symptoms. CONCLUSIONS/SIGNIFICANCE:This meta-analysis suggests that clinically significant PTSD symptoms induced by ACS are moderately prevalent and are associated with increased risk for recurrent cardiac events and mortality. Further tests of the association of ACS-induced PTSD and clinical outcomes are needed
Multiple Redox Modes in the Reversible Lithiation of High-Capacity, Peierls-Distorted Vanadium Sulfide.
This is the author accepted manuscript. The final version is available from ACS via http://dx.doi.org/10.1021/jacs.5b03395Vanadium sulfide VS4 in the patronite mineral structure is a linear chain compound comprising vanadium atoms coordinated by disulfide anions [S2](2-). (51)V NMR shows that the material, despite having V formally in the d(1) configuration, is diamagnetic, suggesting potential dimerization through metal-metal bonding associated with a Peierls distortion of the linear chains. This is supported by density functional calculations, and is also consistent with the observed alternation in V-V distances of 2.8 and 3.2 Å along the chains. Partial lithiation results in reduction of the disulfide ions to sulfide S(2-), via an internal redox process whereby an electron from V(4+) is transferred to [S2](2-) resulting in oxidation of V(4+) to V(5+) and reduction of the [S2](2-) to S(2-) to form Li3VS4 containing tetrahedral [VS4](3-) anions. On further lithiation this is followed by reduction of the V(5+) in Li3VS4 to form Li3+xVS4 (x = 0.5-1), a mixed valent V(4+)/V(5+) compound. Eventually reduction to Li2S plus elemental V occurs. Despite the complex redox processes involving both the cation and the anion occurring in this material, the system is found to be partially reversible between 0 and 3 V. The unusual redox processes in this system are elucidated using a suite of short-range characterization tools including (51)V nuclear magnetic resonance spectroscopy (NMR), S K-edge X-ray absorption near edge spectroscopy (XANES), and pair distribution function (PDF) analysis of X-ray data.SB acknowledges Schlumberger Stichting Fund and European Research Council (EU ERC) for funding. JC thanks BK21 plus project of Korea. We thank Phoebe Allan and Andrew J. Morris, University of Cambridge, for useful discussions. We also thank Trudy Bolin and Tianpin Wu of Beamline 9-BM, Argonne National Laboratory for help with XANES measurements. The DFT calculations were performed at the UCSB Center for Scientific Computing at UC Santa Barbara, supported by the California Nanosystems Institute (NSF CNS-0960316), Hewlett-Packard, and the Materials Research Laboratory (DMR-1121053). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357
Effect of a Dipeptidyl Peptidase-IV Inhibitor, Des-Fluoro-Sitagliptin, on Neointimal Formation after Balloon Injury in Rats
Background: Recently, it has been suggested that enhancement of incretin effect improves cardiac function. We investigated the effect of a DPP-IV inhibitor, des-fluoro-sitagliptin, in reducing occurrence of restenosis in carotid artery in response to balloon injury and the related mechanisms. Methods and Findings: Otsuka Long-Evans Tokushima Fatty rats were grouped into four: control (normal saline) and sitagliptin 100, 250 and 500 mg/kg per day (n = 10 per group). Sitagliptin or normal saline were given orally from 1 week before to 2 weeks after carotid injury. After 3 weeks of treatment, sitagliptin treatment caused a significant and dose-dependent reduction in intima-media ratio (IMR) in obese diabetic rats. This effect was accompanied by improved glucose homeostasis, decreased circulating levels of high-sensitivity C-reactive protein (hsCRP) and increased adiponectin level. Moreover, decreased IMR was correlated significantly with reduced hsCRP, tumor necrosis factor- and monocyte chemoattractant protein-1 levels and plasminogen activator inhibitor-1 activity. In vitro evidence with vascular smooth muscle cells (VSMCs) demonstrated that proliferation and migration were decreased significantly after sitagliptin treatment. In addition, sitagliptin increased caspase-3 activity and decreased monocyte adhesion and NFκB activation in VSMCs. Conclusions: Sitagliptin has protective properties against restenosis after carotid injury and therapeutic implications for treating macrovascular complications of diabetes
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