Ref HAL: hal-02563181_v1
DOI: 10.1063/1.5142605
WoS: 000519911600001
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We adapt and apply a recently developed optimization scheme used to obtain effective potentialsfor aluminosilicate glasses to include the network former boron into the interaction parameter set.As input data for the optimization, we used the radial distribution functions of the liquid at hightemperature generated by ab initio molecular dynamics simulations, and density, coordination andelastic modulus of glass at room temperature from experiments. The new interaction potentials areshown to reproduce reliably the structure, coordination and mechanical properties over a widerange of compositions for binary alkali borates. Furthermore, the transferability of these newinteraction parameters allows mixing to reliably reproduce properties of various boroaluminateand borosilicate glasses.

Ref HAL: hal-02540128_v1
Ref Arxiv: 1908.01484
DOI: 10.1021/acs.macromol.9b02166
WoS: 000526399500029
Ref. & Cit.: NASA ADS
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1 Citation
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In order to determine in polymeric systems the geometrical mesh size ξ, we simulate a solution of coarse-grained polymers with densities ranging from the dilute to the concentrated regime and for different chain lengths. We determine the monomer density fluctuation correlation length ξc from the monomer structure factor as well as the radial distribution function, showing that the identification ξ = ξc is not justified outside of the semidilute regime. In order to better characterize ξ, we compute the pore size distribution (PSD) following two different definitions, one by Torquato et al. and one by Gubbins et al. We find that the mean values of the two distributions, ⟨r⟩T and ⟨r⟩G, display the behavior predicted for ξ by scaling theory, and argue that ξ can be identified with either one of these quantities. This identification allows to interpret the PSD as the distribution of mesh sizes, a quantity which conventional methods cannot access. Finally, we show that it is possible to map a polymer solution on a system of hard or overlapping spheres, for which Torquato’s PSD can be computed analytically and reproduces accurately the PSD of the solution. We give an expression that allows ⟨r⟩T to be estimated with high accuracy in the semidilute regime by knowing only the radius of gyration and the density of the polymers.

Ref HAL: lirmm-02470184_v1
PMID 32174314
DOI: 10.1016/j.compbiomed.2020.103638
WoS: 000527937200013
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Background: Partial arterial pressure of carbon dioxide (CO2) modulates cerebral blood flow through a vasoreactivity mechanism. Near infrared spectroscopy (NIRS) can be used to record these changes in cerebral hemodynamics. However, no laterality comparison of the NIRS signal has been performed despite being a prerequisite for the use of such a method in a vasoreactivity monitoring context. We propose to investigate the NIRS signal laterality in response to a CO2-inhalation-based hypercapnia paradigm in healthy volunteers.Methods: Eleven healthy volunteers (6 women, 5 men, mean age: 31 ± 11) underwent a 3-block-design inhalation paradigm: normoxia (5min, "baseline") - hypercapnia (2min, "stimulation") - normoxia (5min, "post-stimulation"). NIRS signal was measured using a two-channel oximeter (INVOS 5100C, Medtronic, USA) with sensors placed symmetrically on both left and right sides on each subject's forehead. Additional heart rate (HR) monitoring was performed simultaneously. Based on the NIRS mean signal pattern, an a priori model of parametric identification was applied for each channel to quantify parameters of interest (amplitude, time delay, excitation and post-stimulation time) for each inhalation block.Results: HR increased significantly during the stimulation block. The quality of the model was satisfactory: mean absolute errors between modeled and experimental signals were lower than the resolution of the device. No significant lateralization was found between left and right values of most of the parameters.Conclusion: Due to the lack of lateralization, this parametric identification of NIRS responses to hypercapnia could bring light to a potential asymmetry and be used as a biomarker in patients with cerebrovascular diseases.

Ref HAL: hal-02464734_v1
Ref Arxiv: 2001.11670
DOI: 10.1103/PhysRevD.101.074009
WoS: 000525109000003
Ref. & Cit.: NASA ADS
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We reconsider our former determination of the chiral quark condensate $\langle \bar q q \rangle$ from the related QCD spectral density of the Euclidean Dirac operator, using our Renormalization Group Optimized Perturbation (RGOPT) approach. Thanks to the recently available {\em complete} five-loop QCD RG coefficients, and some other related four-loop results, we can extend our calculations exactly to $N^4LO$ (five-loops) RGOPT, and partially to $N^5LO$ (six-loops), the latter within a well-defined approximation accounting for all six-loop contents exactly predictable from five-loops RG properties. The RGOPT results overall show a very good stability and convergence, giving primarily the RG invariant condensate, $\langle \bar q q\rangle^{1/3}_{RGI}(n_f=0) = -(0.840_{-0.016}^{+0.020}) \bar\Lambda_0 $, $\langle\bar q q\rangle^{1/3}_{RGI}(n_f=2) = -(0.781_{-0.009}^{+0.019}) \bar\Lambda_2 $, $\langle\bar q q\rangle^{1/3}_{RGI}(n_f=3) = -(0.751_{-.010}^{+0.019}) \bar\Lambda_3 $, where $\bar\Lambda_{n_f}$ is the basic QCD scale in the \overline{MS} scheme for $n_f$ quark flavors, and the range spanned is our rather conservative estimated theoretical error. This leads {\it e.g.} to $ \langle\bar q q\rangle^{1/3}_{n_f=3}(2\, {\rm GeV}) = -(273^{+7}_{-4}\pm 13)$ MeV, using the latest $\bar\Lambda_3$ values giving the second uncertainties. We compare our results with some other recent determinations. As a by-product of our analysis we also provide complete five-loop and partial six-loop expressions of the perturbative QCD spectral density, that may be useful for other purposes.

Ref HAL: hal-02526695_v1
DOI: 10.1016/j.rehab.2019.10.009
WoS: 000549977400001
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Few rehabilitation methods have proven their efficacy in increasing sensori-motor recovery and/or function of the upper limb (UL) after stroke. Video games (VGs) are promising tools in this indication.OBJECTIVE: To compare UL rehabilitation by using VGs and conventional rehabilitation (CR) in patients with sub-acute stroke.DESIGN: Single-blind, multicentric trial, with central randomization and stratification by center.SETTING: Physical and rehabilitation medicine departments of 2 university hospitals.PARTICIPANTS: Adults within 3 months after a first vascular cerebral accident, with UL Fugl Meyer Score (UL-FMS)<30/66 and without major cognitive impairment.INTERVENTION: A 45-min additional session of conventional occupational therapy (OT) or a VG-based OT session as add-on therapy to usual rehabilitation programs, 5 days/week for 6 weeks.MAIN OUTCOME MEASURES: Primary outcome: UL-FMS. Secondary outcome: Box and Block Test (BBT), Wolf Motor Function test (WMFT), Motor Activity Log (MAL), Barthel Index and quality of life (SF-36).RESULTS: We included 51 patients (20 women) at a mean (SD) of 27.2 (19.4) days post-stroke (mean age 58 years [range 24-83]), 26 in the CR group and 25 in the VG group (23 in each group at 6-month follow-up). The mean duration of the additional rehabilitation session was similar in both groups: 29.3 (4.3) vs 28.0 (4.4) min in CR and VG groups. Shoulder pain occurred in 4 patients in the VG group versus 7 in the CR group. At day 45, gain in UL-FMS did not significantly differ between the groups (CR mean 17.8 [14.6] vs VG 24.1 [14.8]; P=0.10), whereas gain in BBT was doubled in the VG group (CR 7.4 [12.2] vs VG 15.7 [16.3]; P=0.02). At 6-month follow-up, the study was inconclusive about between-group differences in UL-FMS, BBT and other criteria. Post-hoc analysis showed that gains in UL-FMS or BBT were significantly higher in the VG than CR group for patients included within 30 days post-stroke.CONCLUSION: In general, we cannot conclude that video gaming and conventional OT led to different long-term sensorimotor recovery of the UL after sub-acute stroke. However, when applied within the first month after stroke, video gaming was more efficient than conventional rehabilitation on both sensorimotor recovery and gross grasping function.

Ref HAL: hal-02423733_v1
Ref Arxiv: 1912.06958
Ref INSPIRE: 1770954
DOI: 10.1103/PhysRevD.101.103501
WoS: 000529824500006
Ref. & Cit.: NASA ADS
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We analyze the global behavior of the growth index of cosmic inhomogeneities in an isotropic homogeneous universe filled by cold nonrelativistic matter and dark energy (DE) with an arbitrary equation of state. Using a dynamical system approach, we find the critical points of the system. That unique trajectory for which the growth index γ is finite from the asymptotic past to the asymptotic future is identified as the so-called heteroclinic orbit connecting the critical points (Ωm=0,γ∞) in the future and (Ωm=1,γ-∞) in the past. The first is an attractor while the second is a saddle point, confirming our earlier results. Further, in the case when a fraction of matter (or DE tracking matter) ϵΩmtot remains unclustered, we find that the limit of the growth index in the past γ-∞ϵ does not depend on the equation of state of DE, in sharp contrast with the case ϵ=0 (for which γ-∞ is obtained). We show indeed that there is a mathematical discontinuity: one cannot obtain γ-∞ by taking limϵ→0γ-∞ϵ (i.e., the limits ϵ→0 and Ωmtot→1 do not commute). We recover in our analysis that the value γ-∞ϵ corresponds to tracking DE in the asymptotic past with constant γ=γ-∞ϵ found earlier.

Ref HAL: hal-02391672_v1
Ref Arxiv: 2010.00214
DOI: 10.1016/j.molcel.2020.06.034
WoS: 000575919900012
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Liquid-liquid phase-separated (LLPS) states are key to compartmentalizing components in the absence of membranes; however, it is unclear whether LLPS condensates are actively and specifically organized in the subcellular space and by which mechanisms. Here, we address this question by focusing on the ParABS DNA segregation system, composed of a centromeric-like sequence (parS), a DNA-binding protein (ParB), and a motor (ParA). We show that parS and ParB associate to form nanometer-sized, round condensates. ParB molecules diffuse rapidly within the nucleoid volume but display confined motions when trapped inside ParB condensates. Single ParB molecules are able to rapidly diffuse between different condensates, and nucleation is strongly favored by parS. Notably, the ParA motor is required to prevent the fusion of ParB condensates. These results describe a novel active mechanism that splits, segregates, and localizes non-canonical LLPS condensates in the subcellular space.