7 research outputs found
Insights from lowâtemperature thermochronometry into transpressional deformation and crustal exhumation along the San Andreas fault in the western Transverse Ranges, California
The San Emigdio Mountains are an example of an archetypical, transpressional structural system, bounded to the south by the San Andreas strikeâslip fault, and to the north by the active Wheeler Ridge thrust. Apatite (UâTh)/He and apatite and zircon fission track ages were obtained along transects across the range and from wells in and to the north of the range. Apatite (UâTh)/He ages are 4â6âMa adjacent to the San Andreas fault, and both (UâTh)/He and fission track ages grow older with distance to the north from the San Andreas. The young ages north of the San Andreas fault contrast with early Miocene (UâTh)/He ages from Mount Pinos on the south side of the fault. Restoration of sample paleodepths in the San Emigdio Mountains using a regional unconformity at the base of the Eocene Tejon Formation indicates that the San Emigdio Mountains represent a crustal fragment that has been exhumed more than 5âkm along the San Andreas fault since late Miocene time. Marked differences in the timing and rate of exhumation between the northern and southern sides of the San Andreas fault are difficult to reconcile with existing structural models of the western Transverse Ranges as a thinâskinned thrust system. Instead, these results suggest that rheologic heterogeneities may play a role in localizing deformation along the Big Bend of the San Andreas fault as the San Emigdio Mountains are compressed between the crystalline basement of Mount Pinos and oceanic crust that underlies the southern San Joaquin Valley. Key Points There is Pliocene exhumation of the western Transverse Ranges Localization of deformation may be controlled by lithospheric strength Strain is partitioned between the San Andreas and regional thrustsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102707/1/tect20096.pd
Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19
IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19.
Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19.
DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 nonâcritically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022).
INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (nâ=â257), ARB (nâ=â248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; nâ=â10), or no RAS inhibitor (control; nâ=â264) for up to 10 days.
MAIN OUTCOMES AND MEASURES The primary outcome was organ supportâfree days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes.
RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ supportâfree days among critically ill patients was 10 (â1 to 16) in the ACE inhibitor group (nâ=â231), 8 (â1 to 17) in the ARB group (nâ=â217), and 12 (0 to 17) in the control group (nâ=â231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ supportâfree days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively).
CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes.
TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570
Low-angle normal faulting and focused exhumation associated with late Pliocene change in tectonic style in the southern Apennines (Italy)
In the southern Apennines, low-temperature thermochronometry data indicate that exhumation
of previous tectonically buried sedimentary units started at around 10Ma and took placemostly during the last
6Ma. Relatively high exhumation rates are obtained from apatite fission track (AFT) and (U-Th)/He (AHe)
analysis, pointing to a substantial contribution of tectonic processes to rock exhumation besides erosion.
Exhumation rates derived fromnew apatite (U-Th)/He data (AHe) for the last 3Ma are generally lower than rates
determined by AFT data and almost in line with erosion rates inferred from cosmogenic nuclides and sediment
yield, thus suggesting that tectonic exhumation was dominant during the older exhumation stages of
this region. However, younger cooling ages in the Monte Alpi area from both AFT and AHe analyses point
out focused exhumation during the last 3Ma. Structural and morphotectonic analyses indicate that fast
exhumation occurred specifically in this areaâwhere the Apulian Platform reservoir carbonates, elsewhere
buried beneath a several kilometer-thick allochthonous cover, are exposed at the surfaceâas a result of a
complex interplay between steep-rooted reverse faulting and shallow low-angle extension. This deformation
involved the development of foreland-dipping low-angle normal faults affecting the allochthonous cover units
during the late stages of reverse fault-related anticlinal growth in the underlying buried carbonates. Extension
of the region triggered focused exhumation in the footwall of the extensional low-angle faults, which was
followed by widespread crustal extension and associated development of high-angle normal faults, leading to
surface uplift of Monte Alp