36 research outputs found
Targeted mixing in an array of alternating vortices
Transport and mixing properties of passive particles advected by an array of
vortices are investigated. Starting from the integrable case, it is shown that
a special class of perturbations allows one to preserve separatrices which act
as effective transport barriers, while triggering chaotic advection. In this
setting, mixing within the two dynamical barriers is enhanced while long range
transport is prevented. A numerical analysis of mixing properties depending on
parameter values is performed; regions for which optimal mixing is achieved are
proposed. Robustness of the targeted mixing properties regarding errors in the
applied perturbation are considered, as well as slip/no-slip boundary
conditions for the flow
Chaotic advection and targeted mixing
The advection of passive tracers in an oscillating vortex chain is
investigated. It is shown that by adding a suitable perturbation to the ideal
flow, the induced chaotic advection exhibits two remarkable properties compared
with a generic perturbation : Particles remain trapped within a specific domain
bounded by two oscillating barriers (suppression of chaotic transport along the
channel), and the stochastic sea seems to cover the whole domain (enhancement
of mixing within the rolls)
Smectic ordering in liquid crystal - aerosil dispersions I. X-ray scattering
Comprehensive x-ray scattering studies have characterized the smectic
ordering of octylcyanobiphenyl (8CB) confined in the hydrogen-bonded silica
gels formed by aerosil dispersions. For all densities of aerosil and all
measurement temperatures, the correlations remain short range, demonstrating
that the disorder imposed by the gels destroys the nematic (N) to smectic-A
(SmA) transition. The smectic correlation function contains two distinct
contributions. The first has a form identical to that describing the critical
thermal fluctuations in pure 8CB near the N-SmA transition, and this term
displays a temperature dependence at high temperatures similar to that of the
pure liquid crystal. The second term, which is negligible at high temperatures
but dominates at low temperatures, has a shape given by the thermal term
squared and describes the static fluctuations due to random fields induced by
confinement in the gel. The correlation lengths appearing in the thermal and
disorder terms are the same and show strong variation with gel density at low
temperatures. The temperature dependence of the amplitude of the static
fluctuations further suggests that nematic susceptibility become suppressed
with increasing quenched disorder. The results overall are well described by a
mapping of the liquid crystal-aerosil system into a three dimensional XY model
in a random field with disorder strength varying linearly with the aerosil
density.Comment: 14 pages, 13 figure
Integrative genetic map of repetitive DNA in the sole Solea senegalensis genome shows a Rex transposon located in a proto-sex chromosome
Repetitive sequences play an essential role in the structural and functional evolution of the genome, particularly in the sexual chromosomes. The Senegalese sole (Solea senegalensis) is a valuable flatfish in aquaculture albeit few studies have addressed the mapping and characterization of repetitive DNA families. Here we analyzed the Simple Sequence Repeats (SSRs) and Transposable elements (TEs) content from fifty-seven BAC clones (spanning 7.9 Mb) of this species, located in chromosomes by multiple fluorescence in situ hybridization (m-BAC-FISH) technique. The SSR analysis revealed an average density of 675.1 loci per Mb and a high abundance (59.69%) of dinucleotide coverage was observed, being 'AC' the most abundant. An SSR-FISH analysis using eleven probes was also carried out and seven of the 11 probes yielded positive signals. 'AC' probes were present as large clusters in almost all chromosomes, supporting the bioinformatic analysis. Regarding TEs, DNA transposons (Class II) were the most abundant. In Class I, LINE elements were the most abundant and the hAT family was the most represented in Class II. Rex/Babar subfamily, observed in two BAC clones mapping to chromosome pair 1, showed the longest match. This chromosome pair has been recently reported as a putative sexual proto-chromosome in this species, highlighting the possible role of the Rex element in the evolution of this chromosome. In the Rex1 phylogenetic tree, the Senegalese sole Rex1 retrotransposon could be associated with one of the four major ancient lineages in fish genomes, in which it is included O. latipes
Role of the IFN I system against the VHSV infection in juvenile Senegalese sole (Solea senegalensis)
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