On the adhesion of particles to a cell layer under flow

The non-specific adhesion of spherical particles to a cell substrate is analyzed in a parallel plate flow chamber, addressing the effect of the particle size. Differently from other experiments, the total volume of the injected particles has been fixed, rather than the total number of particles, as the diameter d of the particles is changed from 500 nm up to 10 $\mu$m. From the analysis of the experimental data, simple and instructive scaling adhesion laws have been derived showing that (i) the number of particles adherent to the cell layer per unit surface decreases with the size of the particle as d^(-1.7) ; and consequently (ii) the volume of the particles adherent per unit surface increases with the size of the particles as d^(+1.3). These results are of importance in the "rational design" of nanoparticles for drug delivery and biomedical imaging.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Learning Contextual Bandits in a Non-stationary Environment

Multi-armed bandit algorithms have become a reference solution for handling the explore/exploit dilemma in recommender systems, and many other important real-world problems, such as display advertisement. However, such algorithms usually assume a stationary reward distribution, which hardly holds in practice as users' preferences are dynamic. This inevitably costs a recommender system consistent suboptimal performance. In this paper, we consider the situation where the underlying distribution of reward remains unchanged over (possibly short) epochs and shifts at unknown time instants. In accordance, we propose a contextual bandit algorithm that detects possible changes of environment based on its reward estimation confidence and updates its arm selection strategy respectively. Rigorous upper regret bound analysis of the proposed algorithm demonstrates its learning effectiveness in such a non-trivial environment. Extensive empirical evaluations on both synthetic and real-world datasets for recommendation confirm its practical utility in a changing environment.Comment: 10 pages, 13 figures, To appear on ACM Special Interest Group on Information Retrieval (SIGIR) 201

Pervasive Displays Research: What's Next?

Reports on the 7th ACM International Symposium on Pervasive Displays that took place from June 6-8 in Munich, Germany

Fermionic Corrections to Fluid Dynamics from BTZ Black Hole

We reconstruct the complete fermionic orbit of the non-extremal BTZ black hole by acting with finite supersymmetry transformations. The solution satisfies the exact supergravity equations of motion to all orders in the fermonic expansion and the final result is given in terms of fermionic bilinears. By fluid/gravity correspondence, we derive linearized Navier-Stokes equations and a set of new differential equations from Rarita-Schwinger equation. We compute the boundary energy-momentum tensor and we interpret the result as a perfect fluid with a modified definition of fluid velocity. Finally, we derive the modified expression for the entropy of the black hole in terms of the fermionic bilinears.Comment: 21 pages, Latex2e, no figure

Fermionic Wigs for BTZ Black Holes

We compute the wig for the BTZ black hole, namely the complete non-linear solution of supergravity equations with all fermionic zero modes. We use a "gauge completion" method starting from AdS_3 Killing spinors to generate the gravitinos fields associated to the BH and we compute the back-reaction on the metric. Due to the anticommutative properties of the fermionic hairs the resummation of these effects truncates at some order. We illustrate the technique proposed in a precedent paper in a very explicit and analytical form. We also compute the mass, the angular momentum and other charges with their corrections.Comment: 11 pages, no figure

Autologous cellular method using micrografts of human adipose tissue derived follicle stem cells in androgenic alopecia

Hair bio-engineering has risen at the crossing point of various manipulations to meet a clinical requirement for innovations to advance hair growth. The authors reported the microscopic and trichoscopic results of an autologous cell biological technique to compare, through histological, immunocytochemistry, and cytospin analysis, hair re-growth obtained by micro-grafts from scalp tissue containing Human Intra- and Extra-Dermal Adipose Tissue-Derived Hair Follicle Stem Cells (HD-AFSCs) versus placebo (saline solution). An autologous solution of micro-grafts was obtained from mechanical fragmentation and centrifugation of scalp biopsy's (2 x 2 mm) using "Gentile protocol". The micro-grafts solution was mechanically infiltrated on half of the selected patients' scalps with Androgenic Alopecia (Norwood Hamilton 2-5 and Ludwig 1-2). The other half was infiltrated with saline solution. Three injections were performed to each patient at 45-day intervals. Of the 35 patients who were enrolled, 1 was excluded and 1 was rejected. 23 and 44 weeks after the last micro graft's injections, the patients displayed a hair density improvement, with a mean increment of 33% 7.5% and 27% 3.5% respectively, contrasted with baseline values, for the treated region. Microscopic assessment appeared, in scalp biopsies, to show an expansion in the number of hair follicles per mm2 following 11 months from the last micro-grafts application compared with baseline (1.4 + 0.27 versus 0.46 + 0.15, respectively; p < 0.05). HD-AFSCs contained in micro-grafts may represent a safe and effective alternative therapy option against hair loss

Control of magnetism in singlet-triplet superconducting heterostructures

We analyze the magnetization at the interface between singlet and triplet superconductors and show that its direction and dependence on the phase difference across the junction are strongly tied to the structure of the triplet order parameter as well as to the pairing interactions. We consider equal spin helical, opposite spin chiral, and mixed symmetry pairing on the triplet side and show that the magnetization vanishes at $\phi=0$ only in the first case, follows approximately a $\cos\phi$ behavior for the second, and shows higher harmonics for the last configuration. We trace the origin of the magnetization to the magnetic structure of the Andreev bound states near the interface, and provide a symmetry-based explanation of the results. Our findings can be used to control the magnetization in superconducting heterostructures and to test symmetries of spin-triplet superconductors.Comment: 5 pages, 3 figure

Comment on "Scalar-tensor gravity coupled to a global monopole and flat rotation curves" by Lee and Lee

The recent paper by Lee and Lee (2004) may strongly leave the impression that astronomers have established that the rotation curves of spiral galaxies are flat. We show that the old paradigm of Flat Rotation Curves lacks, today, any observational support and following it at face value leads to intrinsically flawed alternatives to the Standard Dark Matter Scenario. On the other side, we claim that the rich systematics of spiral galaxy rotation curves, that reveals, in the standard Newtonian Gravity framework, the phenomenon of dark matter, in alternative scenarios, works as a unique benchmark.Comment: 3 pages, 2 figures, accepted in Phys. Rev.