Conical Interfaces between Two Immiscible Fluids Induced by an Optical Laser Beam

We demonstrate the existence of conical interface deformations induced by a laser beam that are similar to Taylor cones in the electrical regime. We show that the cone morphology can be manipulated by fluid and laser parameters. A theory is proposed to quantitatively describe these dependences in good agreement with experimental data obtained for different fluid systems with low interfacial tensions. Counterintuitively, the cone angle is proved to be independent of the refractive index contrast at leading order. These results open a new optofluidic route towards optical spraying technology-an analogue of electrospraying-and more generally for the optical shaping of interfaces.

Transcatheter pulmonary valvuloplasty in neonates with pulmonary atresia and intact ventricular septum

BACKGROUND

Transcatheter pulmonary valvuloplasty in neonates with pulmonary atresia and intact ventricular septum (PA-IVS) or duct-dependent pulmonary valve stenosis (DD-PVS) has become a reasonable alternative to surgical right ventricle decompression.

AIM

To investigate mid-term outcomes following pulmonary valvuloplasty.

METHODS

Sixty-five neonates with PA-IVS (n=29) or DD-PVS (n=36) (median age 4 days; mean weight 3.0kg) undergoing pulmonary valvuloplasty were reviewed retrospectively. Procedural data and clinical outcomes were assessed.

RESULTS

Pulmonary valvuloplasty was successful in 59 patients (90.8%). Preterm birth, larger tricuspid valve annulus diameter and PA-IVS correlated with procedural failure. Eleven patients (18.6%) required a Blalock-Taussig shunt during early follow-up, despite valvuloplasty. These neonates had smaller tricuspid and pulmonary valve annulus Z-scores (-1.9 vs. -0.8 [p=0.04] and -2.5 vs. -0.9 [P=0.005], respectively) and a higher incidence of "bipartite" right ventricle (P=0.02). Mean follow-up was 5.4±3.3 years. Mortality after successful valvuloplasty was 8.5% (n=5). Among the 54 survivors, biventricular repair was achieved in 52 patients (96.3%), including nine with a previous Blalock-Taussig shunt. The cumulative rate of subsequent surgery (excluding Blalock-Taussig shunt) was 13.7% (95% confidence interval 6.8-26.7%) and 16.4% (95% confidence interval 8.5-30.4%) at 2 and 4 years, respectively. Secondary surgery was significantly more frequent in PA-IVS compared with DD-PVS, and in neonates with a Blalock-Taussig shunt (P=0.003 and 0.01, respectively).

CONCLUSIONS

Selected neonates with DD-PVS or PA-IVS managed by transcatheter pulmonary valvuloplasty had a good mid-term outcome. In neonates with a borderline small right ventricle, a hybrid strategy with a supplementary source of pulmonary blood flow can be efficient to achieve biventricular repair.

Social cognition in autism is associated with the neurodevelopment of the posterior superior temporal sulcus

OBJECTIVE

The posterior superior temporal sulcus (pSTS) plays a critical role in the 'social brain'. Its neurodevelopment and relationship with the social impairment in autism spectrum disorders (ASD) are not well understood. We explored the relationship between social cognition and the neurodevelopment of the pSTS in ASD.

METHOD

We included 44 adults with high-functioning ASD and 36 controls. We assessed their performances on the 'Reading the mind in the eyes' test (for 34 of 44 subjects with ASD and 30 of 36 controls), their fixation time on the eyes with eye tracking (for 35 of 44 subjects with ASD and 30 of 36 controls) and the morphology of the caudal branches of the pSTS (length and depth), markers of the neurodevelopment, with structural MRI.

RESULTS

The right anterior caudal ramus of the pSTS was significantly longer in patients with ASD compared with controls (52.6 mm vs. 38.3 mm; P = 1.4 × 10^-3 ; Cohen's d = 0.76). Its length negatively correlated with fixation time on the eyes (P = 0.03) in the ASD group and with the 'Reading the mind in the eyes' test scores in both groups (P = 0.03).

CONCLUSION

Our findings suggest that the neurodevelopment of the pSTS is related to the ASD social impairments.

Infective Endocarditis Risk After Percutaneous Pulmonary Valve Implantation With the Melody and Sapien Valves

OBJECTIVES

This study compared the risk of infective endocarditis (IE) after percutaneous pulmonary valve implantation (PPVI) with the Sapien and Melody valves.

BACKGROUND

The incidence of IE after PPVI is estimated at 3% per year with the Melody valve. The Sapien valve is a more recently marketed valve used for PPVI.

METHODS

We retrospectively included consecutive patients who underwent PPVI at a single center between 2008 and 2016. IE was diagnosed using the modified DUKE criteria.

RESULTS

PPVI was performed in 79 patients (Melody valve, 40.5%; Sapien valve, 59.5%). Median age was 24.9 years (range 18.1 to 34.6). IE occurred in 8 patients (10.1%) at a median of 1.8 years (minimum: 1.0; maximum: 5.6) after surgery. Causative organisms were methicillin-sensitive Staphylococcus aureus (n = 3), Staphylococcus epidermidis (n = 1), Streptococcus mitis (n = 1), Aerococcus viridans (n = 1), Corynebacterium striatum (n = 1), and Haemophilus influenzae (n = 1). All 8 cases occurred after Melody PPVI (25.0% vs. 0.0%). The incidence of IE was 5.7% (95% confidence interval: 2.9% to 11.4%) per person-year after Melody PPVI. The Kaplan-Meier cumulative incidence of IE with Melody PPVI was 24.0% (95% confidence interval: 12.2% to 43.9%) after 4 years and 30.1% (95% confidence interval: 15.8% to 52.5%) after 6 years, compared with 0.0% with the Sapien PPVI after 4 years (p < 0.04 by log-rank test). There was a trend toward a higher incidence of IE in the first 20 patients with Melody PPVI (who received prophylactic antibiotics during the procedure only) and in patients who had percutaneous interventions, dental care, or noncardiac surgery after PPVI.

CONCLUSIONS

IE after PPVI may be less common with the Sapien compared with the Melody valve.

Accuracy of stress measurement by Laue microdiffraction (Laue-DIC method): the influence of image noise, calibration errors and spot number

Laue microdiffraction, available at several synchrotron radiation facilities, is well suited for measuring the intragranular stress field in deformed materials thanks to the achievable submicrometer beam size. The traditional method for extracting elastic strain (and hence stress) and lattice orientation from a microdiffraction image relies on fitting each Laue spot with an analytical function to estimate the peak position on the detector screen. The method is thus limited to spots exhibiting ellipsoidal shapes, thereby impeding the study of specimens plastically deformed. To overcome this difficulty, the so-called Laue-DIC method introduces digital image correlation (DIC) for the evaluation of the relative positions of spots, which can thus be of any shape. This paper is dedicated to evaluating the accuracy of this Laue-DIC method. First, a simple image noise model is established and verified on the data acquired at beamline BM32 of the European Synchrotron Radiation Facility. Then, the effect of image noise on errors on spot displacement measured by DIC is evaluated by Monte Carlo simulation. Finally, the combined effect of the image noise, calibration errors and the number of Laue spots used for data treatment is investigated. Results in terms of the uncertainty of stress measurement are provided, and various error regimes are identified.

Direct measurement of local constitutive relations, at the micrometre scale, in bulk metallic alloys

Multiscale models involving crystal plasticity are essential to predict the elastoplastic behavior of structural materials with respect to their microstructure. However, those models are often limited by a poor knowledge of the local constitutive behavior. This article reports a method to measure the mechanical behavior directly, at the micrometre scale, in bulk crystalline materials. Local strain and stress states were evaluated at the surface of a bent stainless steel crystal by combining total strain measurements – performed with the digital image correlation technique on optical images – with elastic strain measurements obtained by Laue microdiffraction. A local constitutive relation was measured, in an efficient nondestructive way, without the need for full-field simulations. The method was validated by a comparison between the measured local behavior and the macroscopic behavior of the single crystal.