Hydrodynamic interaction in quasi-two-dimensional suspensions

Confinement between two parallel surfaces is found, theoretically and experimentally, to drastically affect the hydrodynamic interaction between colloid particles, changing the sign of the coupling, its decay with distance and its concentration dependence. In particular, we show that three-body effects do not modify the coupling at large distances as would be expected from hydrodynamic screening.Comment: 8 pages, 2 figure

LIF Measurements of the Cylindrical Hall Thruster Plume

This paper presents a Laser Induced Fluorescence (LIF) investigation of ion velocity profiles in the plume of the Fully Cylindrical Hall Thruster (FCHT) recently developed at the Princeton Plasma Physics Laboratory. These measurements confirm a previously measured ∼ 7% increase in the exhaust velocity when the cathode keeper draws an excess current (overrun mode). Furthermore, it was found that velocity directions in the plume remain relatively unchanged for the cusped and direct magnetic field configuration in both overrun and non-overrun modes. It is shown that the reported plume narrowing in the overrun mode is due to the shift of the acceleration and ionization regions inward toward the anode. This conclusion is supported by the potential profiles extracted from the LIF measurements, which indicate that in the overrun mode a larger fraction of potential fall occurs inside the thruster. Recent probe measurements further substantiate these findings [Raitses et al. , Phys. Plasma 16, 057106 (2009)]. The ratio of the potential fall experienced by ions inside the thruster over the actual potential drop within the thruster increases from 20% in the non-overrun regime with magnets in the direct configuration to 70% in the overrun mode with magnets in the cusped configuration. Magnetic field lines outside the thruster channel are found to be not equipotential, with the degree of equipotentiality gradually increasing at the thruster exit toward the edge

Topography and instability of monolayers near domain boundaries

We theoretically study the topography of a biphasic surfactant monolayer in the vicinity of domain boundaries. The differing elastic properties of the two phases generally lead to a nonflat topography of ``mesas'', where domains of one phase are elevated with respect to the other phase. The mesas are steep but low, having heights of up to 10 nm. As the monolayer is laterally compressed, the mesas develop overhangs and eventually become unstable at a surface tension of about K(dc)^2 (dc being the difference in spontaneous curvature and K a bending modulus). In addition, the boundary is found to undergo a topography-induced rippling instability upon compression, if its line tension is smaller than about K(dc). The effect of diffuse boundaries on these features and the topographic behavior near a critical point are also examined. We discuss the relevance of our findings to several experimental observations related to surfactant monolayers: (i) small topographic features recently found near domain boundaries; (ii) folding behavior observed in mixed phospholipid monolayers and model lung surfactants; (iii) roughening of domain boundaries seen under lateral compression; (iv) the absence of biphasic structures in tensionless surfactant films.Comment: 17 pages, 9 figures, using RevTeX and epsf, submitted to Phys Rev

Experimental Study of the Radiative Decays K+ -> mu+ nu e+e- and K+ -> e+ nu e+e-

Experiment 865 at the Brookhaven AGS obtained 410 K+ -> e+ nu e+e- and 2679 K+ -> mu+ nu e+e- events including 10% and 19% background. The branching ratios were measured to be (2.48+-0.14(stat.)+-0.14(syst.))x10^-8 (m_ee>150 MeV) and (7.06+-0.16+-0.26)x10^-8 (m_ee>145 MeV), respectively. Results for the decay form factors are presented.Comment: 4 pages, 3 figures, RevTeX

Relativistic Calculation of two-Electron one-Photon and Hypersatellite Transition Energies for 12≤Z≤3012\leq Z\leq30 Elements

Energies of two-electron one-photon transitions from initial double K-hole states were computed using the Dirac-Fock model. The transition energies of competing processes, the K$\alpha$ hypersatellites, were also computed. The results are compared to experiment and to other theoretical calculations.Comment: accepted versio

Multiple-length-scale elastic instability mimics parametric resonance of nonlinear oscillators

Spatially confined rigid membranes reorganize their morphology in response to the imposed constraints. A crumpled elastic sheet presents a complex pattern of random folds focusing the deformation energy while compressing a membrane resting on a soft foundation creates a regular pattern of sinusoidal wrinkles with a broad distribution of energy. Here, we study the energy distribution for highly confined membranes and show the emergence of a new morphological instability triggered by a period-doubling bifurcation. A periodic self-organized focalization of the deformation energy is observed provided an up-down symmetry breaking, induced by the intrinsic nonlinearity of the elasticity equations, occurs. The physical model, exhibiting an analogy with parametric resonance in nonlinear oscillator, is a new theoretical toolkit to understand the morphology of various confined systems, such as coated materials or living tissues, e.g., wrinkled skin, internal structure of lungs, internal elastica of an artery, brain convolutions or formation of fingerprints. Moreover, it opens the way to new kind of microfabrication design of multiperiodic or chaotic (aperiodic) surface topography via self-organization.Comment: Submitted for publicatio

Valsartan Improves β-Cell Function and Insulin Sensitivity in Subjects With Impaired Glucose Metabolism: A randomized controlled trial

OBJECTIVE Recently, the Nateglinide and Valsartan in Impaired Glucose Tolerance Outcomes Research Trial demonstrated that treatment with the angiotensin receptor blocker (ARB) valsartan for 5 years resulted in a relative reduction of 14% in the incidence of type 2 diabetes in subjects with impaired glucose metabolism (IGM). We investigated whether improvements in beta-cell function and/or insulin sensitivity underlie these preventive effects of the ARB valsartan in the onset of type 2 diabetes. RESEARCH DESIGN AND METHODS In this randomized controlled, double-blind, two-center study, the effects of 26 weeks of valsartan (320 mg daily; n = 40) or placebo (n = 39) on beta-cell function and insulin sensitivity were assessed in subjects with impaired fasting glucose and/or impaired glucose tolerance, using a combined hyperinsulinemic-euglycemic and hyperglycemic clamp with subsequent arginine stimulation and a 2-h 75-g oral glucose tolerance test (OGTT). Treatment effects were analyzed using ANCOVA, adjusting for center, glucometabolic status, and sex. RESULTS Valsartan increased first-phase (P = 0.028) and second-phase (P = 0.002) glucose-stimulated insulin secretion compared with placebo, whereas the enhanced arginine-stimulated insulin secretion was comparable between groups (P = 0.25). In addition, valsartan increased the OGTT-derived insulinogenic index (representing first-phase insulin secretion after an oral glucose load; P = 0.027). Clamp-derived insulin sensitivity was significantly increased with valsartan compared with placebo (P = 0.049). Valsartan treatment significantly decreased systolic and diastolic blood pressure compared with placebo (P < 0.001). BMI remained unchanged in both treatment groups (P = 0.89). CONCLUSIONS Twenty-six weeks of valsartan treatment increased glucose-stimulated insulin release and insulin sensitivity in normotensive subjects with IGM. These findings may partly explain the beneficial effects of valsartan in the reduced incidence of type 2 diabetes

Microparticle-mediated transfer of the viral receptors CAR and CD46, and the CFTR channel in a CHO cell model confers new functions to target cells

Cell microparticles (MPs) released in the extracellular milieu can embark plasma membrane and intracellular components which are specific of their cellular origin, and transfer them to target cells. The MP-mediated, cell-to-cell transfer of three human membrane glycoproteins of different degrees of complexity was investigated in the present study, using a CHO cell model system. We first tested the delivery of CAR and CD46, two monospanins which act as adenovirus receptors, to target CHO cells. CHO cells lack CAR and CD46, high affinity receptors for human adenovirus serotype 5 (HAdV5), and serotype 35 (HAdV35), respectively. We found that MPs derived from CHO cells (MP-donor cells) constitutively expressing CAR (MP-CAR) or CD46 (MP-CD46) were able to transfer CAR and CD46 to target CHO cells, and conferred selective permissiveness to HAdV5 and HAdV35. In addition, target CHO cells incubated with MP-CD46 acquired the CD46-associated function in complement regulation. We also explored the MP-mediated delivery of a dodecaspanin membrane glycoprotein, the CFTR to target CHO cells. CFTR functions as a chloride channel in human cells and is implicated in the genetic disease cystic fibrosis. Target CHO cells incubated with MPs produced by CHO cells constitutively expressing GFP-tagged CFTR (MP-GFP-CFTR) were found to gain a new cellular function, the chloride channel activity associated to CFTR. Time-course analysis of the appearance of GFP-CFTR in target cells suggested that MPs could achieve the delivery of CFTR to target cells via two mechanisms: the transfer of mature, membrane-inserted CFTR glycoprotein, and the transfer of CFTR-encoding mRNA. These results confirmed that cell-derived MPs represent a new class of promising therapeutic vehicles for the delivery of bioactive macromolecules, proteins or mRNAs, the latter exerting the desired therapeutic effect in target cells via de novo synthesis of their encoded proteins

Small but crucial : the novel small heat shock protein Hsp21 mediates stress adaptation and virulence in Candida albicans

Peer reviewedPublisher PD