328 research outputs found
Early sedimentation and crossover kinetics in an off-critical phase-separating liquid mixture
Early sedimentation in a liquid mixture off-critically quenched in its
miscibility gap was investigated with a light attenuation technique. The time
evolution of the droplets distribution is characteristic of an emulsion
coalescing by gravitational collisions. This sedimentation behaviour has given
access to the phase-separating kinetics and a crossover on the way toward
equilibrium was observed, which separates free growth from conserved
order-parameter coarsening with a crossover time fitting well to theoretical
predictions
Toward a complete description of nucleation and growth in liquid-liquid phase separation
The phase separation mechanism of a binary liquid mixture off-critically
quenched in its miscibility gap is nucleation and growth, its homogeneous phase
reaching a metastable equilibrium state. The successive stages of growth of the
nucleated droplets are a diffusion-driven free growth, an intermediate regime
and a coarsening by reduction of interface (Ostwald ripening or Brownian
collisions induced coalescence). We have made light attenuation experiments to
investigate the sedimentation in such systems. These results have given us
access experimentally to two values predicted theoretically: the growth
exponent of the intermediate regime and the crossover time between this regime
and interface-reduction coarsening. These data, added to the literature
results, have permitted to get a quite complete view of the growth scenario in
very off-critical phase-separating liquids
Crack patterns in drying protein solution drops
A deposited drop of bovine serum albumin salt solution experiences both
gelation and fracturation during evaporation. The cracks appearing at the edge
of the gelling drop are regularly spaced, due to the competition between the
evaporation-induced and relaxation-induced stress evolution. Subsequently, the
mean crack spacing evolves in an unexpected way, being inversely proportional
instead of proportional to the deposit thickness. This evolution has been
ascribed to the change with time of the average shrinkage stress, the crack
patterning being purely elastic instead of evaporation-controlled
Generalized Inpainting Method for Hyperspectral Image Acquisition
A recently designed hyperspectral imaging device enables multiplexed
acquisition of an entire data volume in a single snapshot thanks to
monolithically-integrated spectral filters. Such an agile imaging technique
comes at the cost of a reduced spatial resolution and the need for a
demosaicing procedure on its interleaved data. In this work, we address both
issues and propose an approach inspired by recent developments in compressed
sensing and analysis sparse models. We formulate our superresolution and
demosaicing task as a 3-D generalized inpainting problem. Interestingly, the
target spatial resolution can be adjusted for mitigating the compression level
of our sensing. The reconstruction procedure uses a fast greedy method called
Pseudo-inverse IHT. We also show on simulations that a random arrangement of
the spectral filters on the sensor is preferable to regular mosaic layout as it
improves the quality of the reconstruction. The efficiency of our technique is
demonstrated through numerical experiments on both synthetic and real data as
acquired by the snapshot imager.Comment: Keywords: Hyperspectral, inpainting, iterative hard thresholding,
sparse models, CMOS, Fabry-P\'ero
Exploring the role of networks in reconciling endogenous and exogenous drivers of business development in rural areas
This paper presents an explorative study through focus groups in 9 rural EU regions. It studies the importance of - and relationship between endogenous and exogenous drivers of rural business development. The analysis describes which drivers are perceived important by rural entrepreneurs and rural development experts and classifies them endogenous or exogenous. The findings stress the importance of social networks to anticipate on exogenous drivers. This complies with social capital theory stating that âbridgingâ relations are more efficient in transferring specific knowledge than âbondingâ relations. Eventually, research hypotheses are formulated for better understanding how to reconcile endogenous and exogenous drivers
Five days of postoperative antimicrobial therapy decreases infectious complications following pancreaticoduodenectomy in patients at risk for bile contamination
AbstractObjectivesPancreaticoduodenectomy (PD) is associated with high morbidity, in part as a result of infectious complications increased by preoperative bile contamination. The aim of the present study was to assess the effect on the incidence of infectious complications of shortâterm antimicrobial therapy (AMT) in highârisk patients.MethodsPatients with a high risk for positive intraoperative bile culture (i.e. those with ampulloma or pancreatic adenocarcinoma with preoperative endoscopic procedures) (highârisk group, n = 99) were compared with lowârisk patients (i.e. those with pancreatic adenocarcinoma without preoperative endoscopic procedures) (lowârisk group, n = 76). The highârisk group received a 5âday course of perioperative AMT secondarily adapted to the bile antibiogram. The lowârisk group received only the usual antimicrobial prophylaxis.ResultsPositive bile cultures were significantly more frequent in highârisk patients (81% versus 12%; P < 0.001). The overall rate of infectious complications was lower in the highârisk group (29% versus 46%; P = 0.018). The statistically significant decrease in the rate of infectious complications reflected reduced rates of urinary tract infections, pulmonary infections and septicaemia. Rates of wound infection (3% versus 5%; P = 0.639) and intraâabdominal abscess (7% versus 7%; P = 0.886) were similar in the highâ and lowârisk groups, as was the need for curative AMT.ConclusionsThis exploratory study suggests that a postoperative short course of AMT in patients at high risk for biliary contamination reduces the overall rate of infectious complications after PD. The adaptation of perioperative antimicrobial policy to the patient's risk for bile contamination seems promising and should be further evaluated
The Asc locus for resistance to Alternaria stem canker in tomato does not encode the enzyme aspartate carbamoyltransferase
The fungal disease resistance locus Alternaria stem canker (Asc) in tomato has been suggested to encode the enzyme aspartate carbamoyltransferase (ACTase). To test this hypothesis a segment of the tomato ACTase gene was amplified by the polymerase chain reaction (PCR) using degenerate primers. The PCR product obtained was subsequently used to isolate an ACTase cDNA clone. Restriction fragment length polymorphism (RFLP) linkage analysis showed that the ACTase gene and the Asc locus do not cosegregate. RFLP mapping positioned the ACTase gene on chromosome 11, while the Asc locus is located on chromosome 3. These results exclude the possibility that the ACTase protein is encoded by the Asc locus
- âŠ