Investigation of the in-plane and out-of-plane electrical properties of metallic nanoparticles in dielectric matrix thin films elaborated by atomic layer deposition.

Pt nanoparticles in a Al2O3 dielectric matrix thin films are elaborated by means of atomic layer deposition. These nanostructured thin films are integrated in vertical and planar test structures in order to assess both their in-plane and out-of-plane electrical properties. A shadow edge evaporation process is used to develop planar devices with electrode separation distances in the range of 30 nm. Both vertical and planar test structures show a Poole-Frenkel conduction mechanism. Low trap energy levels (<0.1 eV) are identified for the two test structures which indicates that the Pt islands themselves are not acting as traps in the PF mechanism. Furthermore, a more than three order of magnitude current density difference is observed between the two geometries. This electrical anisotropy is attributed to a large electron mobility difference in the in-plane and out-of-plane directions which can be related to different trap distributions in both directions.

Validity of urine dipstick test to assess eradication of urinary tract infection in persons with spinal cord injury.

OBJECTIVES: To prospectively study the predictive value (PV) of urine nitrite (NIT) dipstick testing against urine cultures during antibiotic treatment for urinary tract infection (UTI), and other situations, in patients with spinal cord injury (SCI). METHODS: Inpatients with SCI on intermittent catheterisation (IC) or a Foley indwelling catheter (FC) were included. Urine specimens were collected in patients without symptoms (routine), with symptoms of UTI (suspicion), and on day 4 of a 5-day antibiotic treatment (ATB+3). RESULTS: A total of 157 urine samples were collected in 61 patients: 34 were on IC (95 samples) and 27 on FC (62 samples). The prevalence of asymptomatic bacteriuria in the urine cultures was 89% in routine (70 samples). At ATB+3, microbiological cure was found in 27/30 specimens (IC group) and 2/6 (FC group). In the routine condition, the specificity and positive PV of the NIT tests was 1.00 and sensitivity 0.63. The negative PV was low in both groups. In suspicion of UTI, the sensitivity was between 0.69 and 0.55, the positive PV was 1.00 and the negative PV 0.00 for both groups. At ATB+3, the negative PV and sensitivity was 1.00, specificity 0.85 and positive PV 0.43 in the IC group, and in the FC group, specificity was 1.00, negative PV 0.33 and sensitivity 0.00. CONCLUSION: In the SCI population on intermittent or indwelling catheters with high prevalence of bacteriuria, dipstick testing helped assess the eradication of germs during antibiotic treatment, but showed no value in the decision making process for UTI. LEVEL OF EVIDENCE: 3.

Fluorescence eXclusion Measurement of volume in live cells.

Volume is a basic physical property of cells; however, it has been poorly investigated in cell biology so far, mostly because it is difficult to measure it precisely. Recently, large efforts were made to experimentally measure mammalian cell size and used mass, density, or volume as proxies for cell size. Here, we describe a method enabling cell volume measurements for single living cells. The method is based on the principle of fluorescent dye exclusion and can be easily implemented in cell biology laboratories. As this method is very versatile, it can be used for cells of different sizes, adherent or growing in suspension, over several cell cycles and is independent of cell shape changes. The method is also compatible with traditional cell biology tools such as epifluorescence imaging or drug treatments.

Geometric friction directs cell migration.

In the absence of environmental cues, a migrating cell performs an isotropic random motion. Recently, the breaking of this isotropy has been observed when cells move in the presence of asymmetric adhesive patterns. However, up to now the mechanisms at work to direct cell migration in such environments remain unknown. Here, we show that a nonadhesive surface with asymmetric microgeometry consisting of dense arrays of tilted micropillars can direct cell motion. Our analysis reveals that most features of cell trajectories, including the bias, can be reproduced by a simple model of active Brownian particle in a ratchet potential, which we suggest originates from a generic elastic interaction of the cell body with the environment. The observed guiding effect, independent of adhesion, is therefore robust and could be used to direct cell migration both in vitro and in vivo.

Spirals and vortex lattices in quasi-self-imaging divide-by-three optical parametric oscillators.

A linear stability analysis is derived in self-imaging cavities for which the conditions for large Fresnel number are stated. In cases of both Fabry-Pérot and ring cavities a Hopf bifurcation is predicted at finite transverse wave number. The self-imaging Fabry-Pérot resonator operates as a longitudinal multimode cavity that invalidates the mean-field model. Above the bifurcation threshold, either vortex lattices, spirals, or targets occur, depending on the Fresnel number, the input intensity, and the mistunings. The time and spatial characteristics have different scales in the case of a self-imaging ring cavity, but the same sort of patterns are reported.

Patterns in a quasiconfocal optical parametric oscillator.

The formation of transverse patterns in a triply resonant optical parametric oscillator is studied both numerically and analytically for a spherical cavity close to confocality. While the pump profile is Gaussian, the signal and idler intensities may be made of many rings, either stationary or time dependent. The mode selection and the time dependence are understood with the help of the linear stability analysis. It might explain observations reported for a quasiconfocal cavity with a KTP crystal.

Example of a chaotic crystal: the labyrinth.

Labyrinthine structures often appear as the final steady state of pattern forming systems. Being disordered, they exhibit the same kind of short range positional order as the Newell-Pomeau turbulent crystal. Labyrinths can be seen as a limit case of the texture of disordered rolls with a coherence length of the same order as the wavelength. In the various two-dimensional model equations we looked at, labyrinths and parallel rolls are steady states for the same parameters, their occurrence depending on the initial conditions. Comparing the stability of these two structures, we find that in variational models their energy is very close, rolls always being more stable than labyrinths. For the nonvariational model we propose a numerical experiment which displays a well defined bifurcation from parallel rolls to labyrinths as the more stable state.

Efficacy and safety of acarbose add-on therapy in the treatment of overweight patients with Type 2 diabetes inadequately controlled with metformin: a double-blind, placebo-controlled study.

This 6-month, double-blind, placebo-controlled, randomised, parallel-group study investigated the potential of acarbose add-on therapy for improving the glycaemic control of overweight patients with Type 2 diabetes and was inadequately controlled with metformin monotherapy. Patients were randomised to receive acarbose titrated up to 100 mg three times daily (n=74) or placebo (n=78). All patients were receiving metformin 850 mg twice or thrice daily before the study and continued to receive this dose throughout the study. The mean difference in glycated haemoglobin (HbA(1c)) (+/-S.D.) from baseline to endpoint was -0.7+/-1.2% U in the acarbose intention-to-treat (ITT) group, compared with +0.2+/-1.3% in the placebo ITT group (P=0.0001). Significantly, more patients in the acarbose group were classified as 'responders', with an HbA(1c) at the end of treatment of less than 7.0% or a decrease by at least 15% relative to baseline (acarbose vs. placebo; 42 vs. 17%; P=0.002). The difference in fasting blood glucose level from baseline to endpoint was -1.0+/-2.8 (S.D.) mmol/l in the acarbose ITT group, compared with +1.3+/-2.8 mmol/l in the placebo ITT group (P=0.0001), and for 2-h postprandial blood glucose level -1.4+/-3.8 vs. +1.1+/-3.5 mmol/l (P=0.0001). In all, 60% of patients in the acarbose group and 33% in the placebo group had an adverse event considered to be possibly or probably related to drug therapy, leading to withdrawal by 15 and 3%, respectively. The results indicate that acarbose has potential clinical utility for improving glycaemic control in overweight patients with Type 2 diabetes inadequately controlled with metformin.

Phase-separation dynamics of circular domain walls in the degenerate optical parametric oscillator.

We study the dynamics of the formation of circular domain walls, which are large-intensity structures, in a degenerate optical parametric oscillator. We show that the mean-field and the propagation models predict the same increase in the domain size proportional to t(1/3) .

[Intestinal flora and social relations in laboratory rats]. / Flores intestinales et relations sociales, chez le rat de laboratoire.

This paper deals with the quantitative study of the social interaction in dyads of laboratory rats. Two kinds of dyads of Rattus norvegicus were observed: one which had the conventional rat intestinal flora (S.S.C.u.p.) and the other a micro-flora (J.L.T.) derived from feral rats, each member of the dyad having the same sex. Contact-seeking and sniffing behaviour were more frequent and lasted longer in J.L.T. rats than in S.S.C.u.p.

Effects of the sex of the resident adult and of the sex of the opponent on interactions in Mongolian gerbils (Meriones unguiculatus).

Mated pairs of Mongolian gerbils were rejoined by two of their own young, one of each sex, after periods of separation starting when the young were four or seven weeks old and lasting either one or four weeks. An additional sub-group of litters was separated when six weeks old, for a period of separation of two weeks. In another group of mated-pairs, mated-adults were introduced and observed in the same way. Occurrences of sniffing, opposition and pursuit between each adult and each intruder was noted over a period of one hour. A clear effect of the sex of the resident adult on agonistic behaviour was evident. The adult female develops its agonistics acts sooner than the male i.e. it is more responsive than the male to a short duration of separation from the juveniles. The adult female shows either pursuit or opposition to juveniles but shows almost no agonistic behaviour in the presence of unrelated adults. As for the adult male, its agonistic acts begin to appear after four weeks of separation and persist with very frequent opposition, in adult-adult meetings. The sex of the intruder only appeared to be a significant factor after four weeks of separation. After four weeks of separation, opposition of the adult male to the young male was significantly higher than that to the young female. Sniffing of the young male by the adult female was significantly higher than that of the young female. With the same period of separation, but with opponents of eleven weeks, as well as in meetings of adults, each resident adult had a greater number of interactions with the intruder of the same sex.