Real-world impact of laparoscopic surgery for rectal cancer: a population-based analysis.

Background: Randomized trials have demonstrated equivalent oncologic outcomes and decreased morbidity in patients with rectal cancer who undergo laparoscopic surgery (lapsx) compared with open surgery (opensx). The objective of the present study was to compare short-term outcomes after lapsx and opensx in a real-world setting.

Methods: A national discharge abstract database was used to identify all patients who underwent rectal cancer resection in Canada (excluding Quebec) from April 2004 through March 2015.

Microscopic mechanisms of the brittleness of viscoelastic fluids.

We show that a large class of viscoelastic fluids, i.e., transient networks, are brittle according to the Griffith's theory of solid fracture.

Structure and rheological properties of model microemulsion networks filled with nanoparticles.

Model microemulsion networks of oil droplets stabilized by non-ionic surfactant and telechelic polymer C18 -PEO(10k)- C18 have been studied for two droplet-to-polymer size ratios. The rheological properties of the networks have been measured as a function of network connectivity and can be described in terms of simple percolation laws. The network structure has been characterised by Small Angle Neutron Scattering (SANS).

Lyotropic structures in a thermotropic liquid crystal.

We have investigated the nature of didodecyldimethylammonium bromide (DDAB)/water aggregates dispersed in 4-n-pentyl-4'-cyanobiphenyl thermotropic liquid crystal (5CB). The structure of this microemulsion has been probed by small-angle neutron and X-ray scattering experiments far above the nematic-to-isotropic phase transition temperature of the solvent. Our data show that the stability of this system is controlled by strong attractive van der Waals interactions between spherical inverted micelles.

Self-diffusion and collective diffusion of charged colloids studied by dynamic light scattering.

A microemulsion of decane droplets stabilized by a nonionic surfactant film is progressively charged by substitution of a nonionic surfactant molecule by a cationic surfactant. We check that the microemulsion droplets remain identical within the explored range of volume fraction (0.02-0.

Loose complexation of weakly charged microemulsion droplets and a polyelectrolyte.

The effect of polyelectrolyte addition on the properties of an oil-in-water (O/W) microemulsion of weakly charged spherical micelles is studied. The 81 A radius O/W droplets in this system can be charged by the partial substitution of the nonionic surfactant by a cationic surfactant. The effect of the addition of poly(acrylic acid) (PAA), which is a charged pH-dependent polyelectrolyte, on the interactions between charged or noncharged droplets has been investigated using SANS.

Quantitative analysis of lyotropic lamellar phases SANS patterns in powder oriented samples.

We have developed a detailed numerical method based on the Caillé model to fit Small Angle Neutron Scattering profiles of powder-oriented lyotropic lamellar phases. We thus obtain quantitative values for the Caillé parameter and the smectic penetration length from which we can derive the smectic compression modulus and the membrane mean bending modulus. Our method, applied to a surfactant lamellar phase system decorated by amphiphilic copolymers, provides excellent fits for any intermembrane spacing or membrane concentration over the entire q-range of the SANS experiments.

Analysis by the two-fluids model of the dynamical behavior of a viscoelastic fluid probed by dynamic light scattering.

The dynamic properties of a model transient network have been studied by dynamic light scattering. The network is formed by microemulsion droplets linked by telechelic polymers (modified hydrophilic polymers with two grafted hydrophobic stickers). We compare the properties of two networks that are similar but for the residence time of the hydrophobic stickers in the droplets.

Entropic phase separation in polymer-microemulsion networks.

We study theoretically a model system of a transient network of microemulsion droplets connected by telechelic polymers and explain recent experimental findings. Despite the absence of any specific interactions between either the droplets or polymer chains, we predict that as the number of polymers per drop is increased, the system undergoes a first-order phase separation into a dense, highly connected phase, in equilibrium with dilute droplets, decorated by polymer loops. The phase transition is purely entropic and is driven by the interplay between the translational entropy of the drops and the configurational entropy of the polymer connections between them.

Self-diffusion and collective diffusion in a model viscoelastic system.

We use dynamic light scattering (DLS) and fluorescence recovery after pattern photobleaching (FRAPP) to investigate the dynamics of a model transient network made of an oil-in-water droplet microemulsion to which small amounts of a telechelic polymer are added. The DLS correlation functions exhibit three relaxation modes. The two first modes can be interpreted quantitatively in the frame of the classical De Gennes-Brochard theory of DLS in viscoelastic system.

Metastable versus unstable transients at the onset of a shear-induced phase transition.

We measure the transient stress response at the onset of shear of a wormlike micelles solution which shows an inhomogenous banded flow pattern above a characteristic rate (.)gamma(t.).

Nonhomogeneous textures and banded flow in a soft cubic phase under shear.

We report evidence for two distinct strain-induced orientation transitions in a lyotropic bcc cubic crystal submitted to increasing shear rates. The crystal is built up from copolymer spherical micelles in a selective solvent. The distribution of orientations is characterized by x-ray diffraction: in the two oriented states, the dense <111> rows align along the flow, but they differ from each other in the orientations of the dense layers with respect to the shear plane.

Microrelief changes in chronically sun-exposed human skin.

The effects of solar exposure on the microtopography of the human skin can be followed, in vivo, by comparing 2 nearby areas, protected and non-protected, of the arm. This has been possible in the case of professional cyclists, whose short-sleeved outerwear provides a clear demarcation of the 2 zones. The microrelief was measured from negative replicas by an automatic image analysis method.