56 research outputs found
Beating the teapot effect
We investigate the dripping of liquids around solid surfaces in the regime of
inertial flows, a situation commonly encountered with the so-called "teapot
effect". We demonstrate that surface wettability is an unexpected key factor in
controlling flow separation and dripping, the latter being completely
suppressed in the limit of superhydrophobic substrates. This unforeseen
coupling is rationalized in terms of a novel hydro-capillary adhesion
framework, which couples inertial flows to surface wettability effects. This
description of flow separation successfully captures the observed dependence on
the various experimental parameters - wettability, flow velocity, solid surface
edge curvature-. As a further illustration of this coupling, a real-time
control of dripping is demonstrated using electro-wetting for contact angle
actuation.Comment: 4 pages; movies at http://lpmcn.univ-lyon1.fr/~lbocque
Making a splash with water repellency
A 'splash' is usually heard when a solid body enters water at large velocity.
This phenomena originates from the formation of an air cavity resulting from
the complex transient dynamics of the free interface during the impact. The
classical picture of impacts on free surfaces relies solely on fluid inertia,
arguing that surface properties and viscous effects are negligible at
sufficiently large velocities. In strong contrast to this large-scale
hydrodynamic viewpoint, we demonstrate in this study that the wettability of
the impacting body is a key factor in determining the degree of splashing. This
unexpected result is illustrated in Fig.1: a large cavity is evident for an
impacting hydrophobic sphere (1.b), contrasting with the hydrophilic sphere's
impact under the very same conditions (1.a). This unforeseen fact is
furthermore embodied in the dependence of the threshold velocity for air
entrainment on the contact angle of the impacting body, as well as on the ratio
between the surface tension and fluid viscosity, thereby defining a critical
capillary velocity. As a paradigm, we show that superhydrophobic impacters make
a big 'splash' for any impact velocity. This novel understanding provides a new
perspective for impacts on free surfaces, and reveals that modifications of the
detailed nature of the surface -- involving physico-chemical aspects at the
nanometric scales -- provide an efficient and versatile strategy for
controlling the water entry of solid bodies at high velocity.Comment: accepted for publication in Nature Physic
Fast multiclonal clusterization of V(D)J recombinations from high-throughput sequencing
International audienceBACKGROUND: V(D)J recombinations in lymphocytes are essential for immunological diversity. They are also usefulmarkers of pathologies. In leukemia, they are used to quantify the minimal residual disease duringpatient follow-up. However, the full breadth of lymphocyte diversity is not fully understood. RESULTS: We propose new algorithms that process high-throughput sequencing (HTS) data to extract unnamedV(D)J junctions and gather them into clones for quantification. This analysis is based on a seedheuristic and is fast and scalable because in the first phase, no alignment is performed with germlinedatabase sequences. The algorithms were applied to TR HTS data from a patient with acutelymphoblastic leukemia, and also on data simulating hypermutations. Our methods identified themain clone, as well as additional clones that were not identified with standard protocols. CONCLUSIONS: The proposed algorithms provide new insight into the analysis of high-troughput sequencing data forleukemia, and also to the quantitative assessment of any immunological profile. The methodsdescribed here are implemented in a C++ open-source program called Vidjil
Quantitative pupillometry in comatose out-of-hospital cardiac arrest patients: A post-hoc analysis of the TTH48 trial
Background: Quantitative pupillometry is an objective method to examine pupil reaction and subsequently grade the response on a neurological pupil index (NPi) scale from 0 to 5. The aim of the present sub-study was to explore the long-term prognostic value of NPi in comatose out-of-hospital cardiac arrest patients undergoing targeted temperature management (TTM).
Methods: This planned sub-study of the “Targeted temperature management for 48 versus 24 h and neurological outcome after out-of-hospital cardiac arrest: A randomized clinical trial.” NPi was assessed from admission and throughout day 3 and linked to the Cerebral Performance Categories score at 6 months. We compared the prognostic performance of NPi in 65 patients randomized to a target temperature of 33 ± 1°C for 24 or 48 h.
Results: The NPi values were not different between TTM groups (p > .05). When data were pooled, NPi was strongly associated with neurological outcome at day 1 with a mean NPi of 3.6 (95% CI 3.4–3.8) versus NPi 3.9 (3.6–4.1) in the poor versus good outcome group, respectively (p < .01). At day 2, NPi values were 3.6 (3.1–4.0) and 4.1 (3.9–4.2) (p = .01) and at day 3, the values were 3.3 (2.6–4.0) and 4.3 (4.1–4.6), respectively (p < .01). The prognostic ability of NPi, defined by area under the receiver operating characteristic curve was best at day three.
Conclusion: Quantitative pupillometry measured by NPi was not different in the two TTM groups, but overall, significantly associated with good and poor neurological outcomes at 6 months. NPI has a promising diagnostic accuracy, but larger studies are warranted.publishedVersio
Electrolyte profiles with induced hypothermia : A sub study of a clinical trial evaluating the duration of hypothermia after cardiac arrest
Background Electrolyte disturbances can result from targeted temperature treatment (TTM) in out-of-hospital cardiac arrest (OHCA) patients. This study explores electrolyte changes in blood and urine in OHCA patients treated with TTM. Methods This is a sub-study of the TTH48 trial, with the inclusion of 310 unconscious OHCA patients treated with TTM at 33 degrees C for 24 or 48 h. Over a three-day period, serum concentrations were obtained on sodium potassium, chloride, ionized calcium, magnesium and phosphate, as were results from a 24-h diuresis and urine electrolyte concentration and excretion. Changes over time were analysed with a mixed-model multivariate analysis of variance with repeated measurements. Results On admission, mean +/- SD sodium concentration was 138 +/- 3.5 mmol/l, which increased slightly but significantly (p < .05) during the first 24 h. Magnesium concentration stayed within the reference interval. Median ionized calcium concentration increased from 1.11 (IQR 1.1-1.2) mmol/l during the first 24 h (p < .05), whereas median phosphate concentration dropped to 1.02 (IQR 0.8-1.2) mmol/l (p < .05) and stayed low. During rewarming, potassium concentrations increased, and magnesium and ionizes calcium concentration decreased (p < .05). Median 24-h diuresis results on days one and two were 2198 and 2048 ml respectively, and the electrolyte excretion mostly stayed low in the reference interval. Conclusions Electrolytes mostly remained within the reference interval. A temporal change occurred in potassium, magnesium and calcium concentrations with TTM's different phases. No hypothermia effect on diuresis was detected, and urine excretion of electrolytes mostly stayed low.Peer reviewe
Severe or critical hypotension during post cardiac arrest care is associated with factors available on admission - a post hoc analysis of the TTH48 trial
Purpose: We explored whether severe or critical hypotension can be predicted, based on patient and resuscitation characteristics in out-of-hospital cardiac arrest (OHCA) patients. We also explored the association of hypotension with mortality and neurological outcome. Materials and methods: We conducted a post hoc analysis of the TTH48 study (NCT01689077), where 355 out-of-hospital cardiac arrest (OHCA) patients were randomized to targeted temperature management (TTM) treatment at 33 degrees C for either 24 or 48 h. We recorded hypotension, according to four severity categories, within four days from admission. We used multivariable logistic regression analysis to test association of admission data with severe or critical hypotension. Results: Diabetes mellitus (OR 3.715, 95% CI 1.180-11.692), longer ROSC delay (OR 1.064, 95% CI 1.022-1.108), admission MAP (OR 0.960, 95% CI 0.929-0.991) and non-shockable rhythm (OR 5.307, 95% CI 1.604-17.557) were associated with severe or critical hypotension. Severe or critical hypotension was associated with increased mortality and poor neurological outcome at 6 months. Conclusions: Diabetes, non-shockable rhythm, longer delay to ROSC and lower admission MAP were predictors of severe or critical hypotension. Severe or critical hypotension was associated with poor outcome. (C) 2020 Published by Elsevier Inc.Peer reviewe
Fast multiclonal clusterization of V(D)J recombinations from high-throughput sequencing
International audienceBACKGROUND: V(D)J recombinations in lymphocytes are essential for immunological diversity. They are also usefulmarkers of pathologies. In leukemia, they are used to quantify the minimal residual disease duringpatient follow-up. However, the full breadth of lymphocyte diversity is not fully understood. RESULTS: We propose new algorithms that process high-throughput sequencing (HTS) data to extract unnamedV(D)J junctions and gather them into clones for quantification. This analysis is based on a seedheuristic and is fast and scalable because in the first phase, no alignment is performed with germlinedatabase sequences. The algorithms were applied to TR HTS data from a patient with acutelymphoblastic leukemia, and also on data simulating hypermutations. Our methods identified themain clone, as well as additional clones that were not identified with standard protocols. CONCLUSIONS: The proposed algorithms provide new insight into the analysis of high-troughput sequencing data forleukemia, and also to the quantitative assessment of any immunological profile. The methodsdescribed here are implemented in a C++ open-source program called Vidjil
a multicentre, randomised, parallel-group, assessor-blinded clinical trial (the TTH48 trial): study protocol for a randomised controlled trial
Background The application of therapeutic hypothermia (TH) for 12 to 24 hours
following out-of-hospital cardiac arrest (OHCA) has been associated with
decreased mortality and improved neurological function. However, the optimal
duration of cooling is not known. We aimed to investigate whether targeted
temperature management (TTM) at 33 ± 1 °C for 48 hours compared to 24 hours
results in a better long-term neurological outcome. Methods The TTH48 trial is
an investigator-initiated pragmatic international trial in which patients
resuscitated from OHCA are randomised to TTM at 33 ± 1 °C for either 24 or 48
hours. Inclusion criteria are: age older than 17 and below 80 years; presumed
cardiac origin of arrest; and Glasgow Coma Score (GCS) <8, on admission. The
primary outcome is neurological outcome at 6 months using the Cerebral
Performance Category score (CPC) by an assessor blinded to treatment
allocation and dichotomised to good (CPC 1–2) or poor (CPC 3–5) outcome.
Secondary outcomes are: 6-month mortality, incidence of infection, bleeding
and organ failure and CPC at hospital discharge, at day 28 and at day 90
following OHCA. Assuming that 50 % of the patients treated for 24 hours will
have a poor outcome at 6 months, a study including 350 patients (175/arm) will
have 80 % power (with a significance level of 5 %) to detect an absolute 15 %
difference in primary outcome between treatment groups. A safety interim
analysis was performed after the inclusion of 175 patients. Discussion This is
the first randomised trial to investigate the effect of the duration of TTM at
33 ± 1 °C in adult OHCA patients. We anticipate that the results of this trial
will add significant knowledge regarding the management of cooling procedures
in OHCA patients
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