Reversible Navier-Stokes equation on logarithmic lattices.

The three-dimensional reversible Navier-Stokes (RNS) equations are a modification of the dissipative Navier-Stokes (NS) equations, first introduced by Gallavotti [Phys. Lett. A 223, 91 (1996)0375-960110.1016/S0375-9601(96)00729-3], in which the energy or the enstrophy is kept constant by adjusting the viscosity over time. Spectral direct numerical simulations of this model were performed by Shukla et al. [Phys. Rev. E 100, 043104 (2019)2470-004510.1103/PhysRevE.100.043104] and Margazoglou et al. [Phys. Rev. E 105, 065110 (2022)10.1103/PhysRevE.105.065110]. Here we consider a linear, forced reversible system obtained by projecting RNS equations on a log lattice rather than on a linearly spaced grid in Fourier space, as is done in regular spectral numerical simulations. We perform numerical simulations of the system at extremely large resolutions, allowing us to explore regimes of parameters that were out of reach of the direct numerical simulations of Shukla et al. Using the nondimensionalized forcing as a control parameter, and the square root of enstrophy as the order parameter, we confirm the existence of a second-order phase transition well described by a mean-field Landau theory. The log-lattice projection allows us to probe the impact of the resolution, highlighting an imperfect transition at small resolutions with exponents differing from the mean-field predictions. Our findings are in qualitative agreement with predictions of a 1D nonlinear diffusive model, the reversible Leith model of turbulence. We then compare the statistics of the solutions of RNS and NS, in order to shed light on an adaptation of the Gallavotti conjecture, in which there is equivalence of statistics between the reversible and irreversible models, to the case where our reversible model conserves either the enstrophy or the energy. We deduce the conditions in which the two are equivalent. Our results support the validity of the conjecture and represent an instance of nonequilibrium system where ensemble equivalence holds for mean quantities.

Varicella post-exposure management for pediatric oncology patients.

INTRODUCTION: The objective was to evaluate health care providers' (HCP) adherence to and efficacy of varicella post-exposure prophylaxis (PEP) recommendations. It was an observational, prospective, multicenter study set in Ile-de-France, France. METHODS: All children under 18 with a cancer diagnosis, currently or within 3months of receiving cancer treatment, regardless of varicella zoster virus (VZV) serostatus or previous personal history of varicella, were eligible. Study participants with significant exposure were reviewed prospectively for PEP indications. Main outcome measures were the percentage of exposure situations for which HCP were guideline-compliant, the proportion of available VZV serostatuses and the incidence of breakthrough varicella after different PEP approaches. RESULTS: A total of 51 patients from 15 centers were enrolled after 52 exposure episodes. Median age at exposure was 5 years (range, 1-15). Exposure within the household led to 38% of episodes. Prophylactic treatment consisted in specific anti-VZV immunoglobulins (V-ZIG) (n=19) or in oral aciclovir (n=15). No prophylactic treatment was given for 18 patients (in compliance, n=16). In compliance with guidelines, 17 patients received V-ZIG, 11 did not develop varicella (65%, [95% CI, 39-90%]); 15 received aciclovir, 13 did not develop varicella (87%, [95% CI, 67-100%]). Breakthrough varicella occurred in 11 patients, with simple clinical course in all cases; in 8/47 (17%) episodes when PEP was guideline-compliant versus 3/5 (60%) when not. DISCUSSION: Recommendations have been respected and are efficient. PEP needs to be standardized and a study carried out to define the optimal approach. Anti-VZV immunization of seronegative family members should be encouraged.

Bench testing of tracheostomy tube-related insults using an instrumented manikin.

PURPOSE: Choosing the right tracheal tube for the right patient is a daily preoccupation for intensivists and emergency physicians. Tracheal tubes can generate severe complications, which are chiefly due to the pressures applied by the tube to the trachea. We designed a bench study to assess the frequency of pressure levels likely to cause tracheal injury. METHODS: We tested the pressure applied on the trachea by 17 tube models of a given size range. To this end, we added a pressure sensor to the posterior tracheal wall of a standardized manikin. RESULTS: Only 2 of the 17 tubes generated pressures under the threshold likely to induce tracheal injury (30 mmHg/3.99 kPa). The force exerted on the posterior wall of the trachea varied widely across tube models. CONCLUSION: Most models of tracheal tubes resulted in forces applied to the trachea that are usually considered capable of causing tracheal tissue injury. LEVEL OF EVIDENCE: Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence: How common is the problem?: step 1; Is this diagnostic or monitoring test accurate? (Diagnosis) step 5; What will happen if we do not add a therapy? (Prognosis) n/a; Does this intervention help? (Treatment Benefits) step 5; What are the COMMON harms?(Treatment Harms) step 5; What are the RARE harms? (Treatment Harms) step 5; Is this (early detection) test worthwhile? (Screening) step 5.

Development of a multiparametric (bio)sensing platform for continuous monitoring of stress metabolites.

There is a growing need for real-time monitoring of metabolic products that could reflect cell damages over extended periods. In this paper, we report the design and development of an original multiparametric (bio)sensing platform that is tailored for the real-time monitoring of cell metabolites derived from cell cultures. Most attractive features of our developed electrochemical (bio)sensing platform are its easy manufacturing process, that enables seamless scale-up, modular and versatile approach, and low cost. In addition, the developed platform allows a multiparametric analysis instead of single-analyte analysis. Here we provide an overview of the sensors-based analysis of four main factors that can indicate a possible cell deterioration problem during cell-culture: pH, hydrogen peroxide, nitric oxide/nitrite and lactate. Herein, we are proposing a sensors platform based on thick-film coupled to microfluidic technology that can be integrated into any microfluidic system using Luer-lock connectors. This platform allows obtaining an accurate analysis of the secreting stress metabolites during cell/tissues culture.

Long duration stabilization of porous silicon membranes in physiological media: Application for implantable reactors.

The natural biodegradabilty of porous silicon (pSi) in physiological media limits its wider usage for implantable systems. We report the stabilization of porous silicon (pSi) membranes by chemical surface oxidation using RCA1 and RCA2 protocols, which was followed by a PEGylation process using a silane-PEG. These surface modifications stabilized the pSi to allow a long period of immersion in PBS, while leaving the pSi surface sufficiently hydrophilic for good filtration and diffusion of several biomolecules of different sizes without any blockage of the pSi structure. The pore sizes of the pSi membranes were between 5 and 20 nm, with the membrane thickness around 70 µm. The diffusion coefficient for fluorescein through the membrane was 2 × 10-10 cm2 s-1, and for glucose was 2.2 × 10-9 cm2 s-1. The pSi membrane maintained that level of glucose diffusion for one month of immersion in PBS. After 2 months immersion in PBS the pSi membrane continued to operate, but with a reduced glucose diffusion coefficient. The chemical stabilization of pSi membranes provided almost 1 week stable and functional biomolecule transport in blood plasma and opens the possibility for its short-term implantation as a diffusion membrane in biocompatible systems.

[Caregivers faced with painful events, testimonials]. / Les soignants face aux événements douloureux, témoignages.

Whatever the profession of caregivers, their activity involves supporting patients and families who are suffering. Doctors and nurses, in particular, talk of the strong emotions which they feel but which they find difficult to express. Being aware of them is essential for being able to accept them and limit their consequences. This article shares different insights.

Design of interpenetrating chitosan and poly(ethylene glycol) sponges for potential drug delivery applications.

Semi-interpenetrating chitosan (CS)/poly(ethylene glycol) (PEG) sponges were designed by crosslinking PEG in the CS matrix via nucleophilic thiol-yne addition. This reaction does not require the use of any potentially cytotoxic catalytic species and offers possibilities to prepare materials with tunable properties. The molecular structure of the sponges was analyzed by FTIR spectroscopy, which provided evidence of intermolecular interactions between PEG and CS, and the presence of a cross-linked PEG network in the CS matrix. The crosslinked CS/PEG sponges displayed a structure with large interconnected pores (tens of micrometers) as demonstrated by scanning electron miscoscopy, in comparison to blended materials with irregular and smaller pores. The crosslinked sponges also exhibited improved mechanical properties (higher Young's modulus) and stability at physiological pH. All together, these interesting properties open the way for the application of this biomaterial in topical drug delivery.

A DNA array based on clickable lesion-containing hairpin probes for multiplexed detection of base excision repair activities.

DNA is under continuous assault by environmental and endogenous reactive oxygen and alkylating species, inducing the formation of mutagenic, toxic and genome destabilizing nucleobase lesions. Due to the implications of such genetic alterations in cell death, aging, inflammation, neurodegenerative diseases and cancer, many efforts have been devoted to developing assays that aim at analyzing DNA repair activities from purified enzymes or cell extracts. The present work deals with the conception and application of a new, miniaturized and parallelized on surface-DNA biosensor to measure base excision repair (BER) activities. Such a bio-analytical tool was built by using the "click chemistry" approach to immobilize, on a glass slide, fluorescent stem-loop DNA probes, which contain a specific nucleobase lesion. The performance of this new high-throughput DNA repair analysis technology was determined by detecting uracil N-glycosylase and AP-endonuclease activities from purified enzymes or in cell extracts. The applications of this device were extended to analyze, in cell extracts, the ability of two inhibitors (Uracil glycosylase inhibitor (Ugi) and methoxyamine (MX)) to block the excision of uracil and the cleavage of AP sites, respectively. Altogether, our results show that this new fluorescent DNA microarray platform provides an easy, rapid and robust method for detecting DNA N-glycosylase and AP-endonuclease activities and evaluating the effects of BER inhibitors in a multiplexed fashion.