371 research outputs found
Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of MamanguĂĄ RĂa, Brazil
Magnetotactic bacteria (MTB) synthesize magnetite and greigite crystals under low oxygen conditions in the water column or uppermost sediment (greigiteâproducing bacteria are found below the oxicâanoxic transition). Dissolved iron and oxygen contents in local environments are known to be limiting factors for the production and preservation of biogenic magnetite. Understanding the processes that link MTB to their living environments is fundamental to reconstructing past chemical variations in the water column and sediment, and for using the magnetic properties of biogenic magnetite as environmental proxy indicators. Previous studies have suggested that the frequently identified biogenic soft (BS) and biogenic hard (BH) magnetite types are associated with equant and more elongated morphologies, respectively, and that their abundance varies in accordance with sedimentary oxygen content, where MTB that produce the BH component live in less oxygenated environments. We test this hypothesis in a highâresolution integrated environmental magnetic and geochemical study of surface sediments from MamanguĂĄ RĂa, SE Brazil. Based on magnetic and pore water profiles, we demonstrate that both the BS and BH components occur within microaerobic environments and that as sediment oxygen content decreases with depth, the BS component disappears before the BH component. With continued burial into the sulfidic diagenetic zone, both components undergo progressive dissolution, but the BH component is more resistant to dissolution than the BS component. Our observations confirm previous inferences about the relative stability of these phases and provide a firmer basis for use of these two types of biogenic magnetite as paleoenvironmental proxies.D. R. and L. J. acknowledge funding
from FAPESP grants 2012/212123 and
2011/22018â3, respectively. F. A.
acknowledges funding from FAPERJ,
CNPq, and CAPES. A. P. R.
acknowledges funding from the
Australian Research Council (grants
DP140104544 and DP160100805)
Prevalence of neoplasia at colonoscopy among testicular cancer survivors treated with platinum-based chemotherapy
Testicular cancer survivors (TCS) treated with platinum-based chemotherapy have an increased risk of colorectal cancer (CRC). We determined the yield of colonoscopy in TCS to assess its potential in reducing CRC incidence and mortality. We conducted a colonoscopy screening study among TCS in four Dutch hospitals to assess the yield of colorectal neoplasia. Neoplasia was defined as adenomas, serrated polyps (SPs), advanced adenomas (AAs: â„10 mm diameter, high-grade dysplasia or â„25% villous component), advanced serrated polyps (ASPs: â„10 mm diameter or dysplasia) or CRC. Advanced neoplasia (AN) was defined as AA, ASP or CRC. Colonoscopy yield was compared to average-risk American males who underwent screening colonoscopy (n = 24,193) using a propensity score matched analysis, adjusted for age, smoking status, alcohol consumption and body mass index. A total of 137 TCS underwent colonoscopy. Median age was 50 years among TCS (IQR 43â57) vs 55 years (IQR 51â62) among American controls. A total of 126 TCS were matched to 602 controls. The prevalence of AN was higher in TCS than in controls (8.7% vs 1.7%; P =.0002). Nonadvanced adenomas and SPs were detected in 45.2% of TCS vs 5.5% of controls (P <.0001). No lesions were detected in 46.0% of TCS vs 92.9% of controls (P <.0001). TCS treated with platinum-based chemotherapy have a higher prevalence of neoplasia and AN than matched controls. These results support our hypothesis that platinum-based chemotherapy increases the risk of colorectal neoplasia in TCS. Cost-effectiveness studies are warranted to ascertain the threshold of AN prevalence that justifies the recommendation of colonoscopy for TCS.</p
Prevalence of neoplasia at colonoscopy among testicular cancer survivors treated with platinum-based chemotherapy
Testicular cancer survivors (TCS) treated with platinum-based chemotherapy have an increased risk of colorectal cancer (CRC). We determined the yield of colonoscopy in TCS to assess its potential in reducing CRC incidence and mortality. We conducted a colonoscopy screening study among TCS in four Dutch hospitals to assess the yield of colorectal neoplasia. Neoplasia was defined as adenomas, serrated polyps (SPs), advanced adenomas (AAs: â„10 mm diameter, high-grade dysplasia or â„25% villous component), advanced serrated polyps (ASPs: â„10 mm diameter or dysplasia) or CRC. Advanced neoplasia (AN) was defined as AA, ASP or CRC. Colonoscopy yield was compared to average-risk American males who underwent screening colonoscopy (n = 24,193) using a propensity score matched analysis, adjusted for age, smoking status, alcohol consumption and body mass index. A total of 137 TCS underwent colonoscopy. Median age was 50 years among TCS (IQR 43â57) vs 55 years (IQR 51â62) among American controls. A total of 126 TCS were matched to 602 controls. The prevalence of AN was higher in TCS than in controls (8.7% vs 1.7%; P =.0002). Nonadvanced adenomas and SPs were detected in 45.2% of TCS vs 5.5% of controls (P <.0001). No lesions were detected in 46.0% of TCS vs 92.9% of controls (P <.0001). TCS treated with platinum-based chemotherapy have a higher prevalence of neoplasia and AN than matched controls. These results support our hypothesis that platinum-based chemotherapy increases the risk of colorectal neoplasia in TCS. Cost-effectiveness studies are warranted to ascertain the threshold of AN prevalence that justifies the recommendation of colonoscopy for TCS.</p
The Enhanced Resolution Imager and Spectrograph for the VLT
ERIS, the Enhanced Resolution Imager and Spectrograph, is an instrument that
both extends and enhances the fundamental diffraction limited imaging and
spectroscopy capability for the VLT. It replaces two instruments that were
being maintained beyond their operational lifetimes, combines their
functionality on a single focus, provides a new wavefront sensing module for
natural and laser guide stars that makes use of the Adaptive Optics Facility,
and considerably improves on their performance. The observational modes ERIS
provides are integral field spectroscopy at 1-2.5 {\mu}m, imaging at 1-5 {\mu}m
with several options for high contrast imaging, and longslit spectroscopy at
3-4 {\mu}m, The instrument is installed at the Cassegrain focus of UT4 at the
VLT and, following its commissioning during 2022, has been made available to
the community.Comment: 19 pages with 29 figures; submitted to A&
Virgo Detector Characterization and Data Quality during the O3 run
The Advanced Virgo detector has contributed with its data to the rapid growth
of the number of detected gravitational-wave signals in the past few years,
alongside the two LIGO instruments. First, during the last month of the
Observation Run 2 (O2) in August 2017 (with, most notably, the compact binary
mergers GW170814 and GW170817) and then during the full Observation Run 3 (O3):
an 11 months data taking period, between April 2019 and March 2020, that led to
the addition of about 80 events to the catalog of transient gravitational-wave
sources maintained by LIGO, Virgo and KAGRA. These discoveries and the manifold
exploitation of the detected waveforms require an accurate characterization of
the quality of the data, such as continuous study and monitoring of the
detector noise. These activities, collectively named {\em detector
characterization} or {\em DetChar}, span the whole workflow of the Virgo data,
from the instrument front-end to the final analysis. They are described in
details in the following article, with a focus on the associated tools, the
results achieved by the Virgo DetChar group during the O3 run and the main
prospects for future data-taking periods with an improved detector.Comment: 86 pages, 33 figures. This paper has been divided into two articles
which supercede it and have been posted to arXiv on October 2022. Please use
these new preprints as references: arXiv:2210.15634 (tools and methods) and
arXiv:2210.15633 (results from the O3 run
Virgo Detector Characterization and Data Quality: results from the O3 run
The Advanced Virgo detector has contributed with its data to the rapid growth
of the number of detected gravitational-wave (GW) signals in the past few
years, alongside the two Advanced LIGO instruments. First during the last month
of the Observation Run 2 (O2) in August 2017 (with, most notably, the compact
binary mergers GW170814 and GW170817), and then during the full Observation Run
3 (O3): an 11-months data taking period, between April 2019 and March 2020,
that led to the addition of about 80 events to the catalog of transient GW
sources maintained by LIGO, Virgo and now KAGRA. These discoveries and the
manifold exploitation of the detected waveforms require an accurate
characterization of the quality of the data, such as continuous study and
monitoring of the detector noise sources. These activities, collectively named
{\em detector characterization and data quality} or {\em DetChar}, span the
whole workflow of the Virgo data, from the instrument front-end hardware to the
final analyses. They are described in details in the following article, with a
focus on the results achieved by the Virgo DetChar group during the O3 run.
Concurrently, a companion article describes the tools that have been used by
the Virgo DetChar group to perform this work.Comment: 57 pages, 18 figures. To be submitted to Class. and Quantum Grav.
This is the "Results" part of preprint arXiv:2205.01555 [gr-qc] which has
been split into two companion articles: one about the tools and methods, the
other about the analyses of the O3 Virgo dat
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