Convergence of Gradient Descent for Low-Rank Matrix Approximation

This paper provides a proof of global convergence of gradient search for low-rank matrix approximation. Such approximations have recently been of interest for large-scale problems, as well as for dictionary learning for sparse signal representations and matrix completion. The proof is based on the interpretation of the problem as an optimization on the Grassmann manifold and Fubiny-Study distance on this space

Surface topography regulates wnt signaling through control of primary cilia structure in mesenchymal stem cells

The primary cilium regulates cellular signalling including influencing wnt sensitivity by sequestering β-catenin within the ciliary compartment. Topographic regulation of intracellular actin-myosin tension can control stem cell fate of which wnt is an important mediator. We hypothesized that topography influences mesenchymal stem cell (MSC) wnt signaling through the regulation of primary cilia structure and function. MSCs cultured on grooves expressed elongated primary cilia, through reduced actin organization. siRNA inhibition of anterograde intraflagellar transport (IFT88) reduced cilia length and increased active nuclear β-catenin. Conversely, increased primary cilia assembly in MSCs cultured on the grooves was associated with decreased levels of nuclear active β-catenin, axin-2 induction and proliferation, in response to wnt3a. This negative regulation, on grooved topography, was reversed by siRNA to IFT88. This indicates that subtle regulation of IFT and associated cilia structure, tunes the wnt response controlling stem cell differentiation.We acknowledge funding from an EPSRC Platform grant which supported McMurray and a Wellcome Trust project grant which supported Wann and McMurray. Wann is now supported on an ARUK project grant. Thompson was funded by a BBSRC PhD studentshi

Détermination des épaisseurs de films très minces de SiO2\mathsf{_2} sur silicium par microscopie électronique en transmission, ellipsométrie spectroscopique et spectroscopie de photoélectrons

High Resolution cross-sectional Transmission Electron Microscopy (HRTEM), Spectroscopic ellipsometry and X-ray photoelectron spectroscopy (XPS) have been used conjointly to measure accurately the thickness of very thin SiO$_2$ films (20-200 Å) of electronic quality. HRTEM has been used to calibrate both ellipsometry and XPS technics. A procedure to measure the absolute oxide film thicknesses has been defined for each of the three methods.La Microscopie Electronique en Transmission à Haute Résolution (METHR), l'ellipsométrie spectroscopique et la spectroscopie de photoélectrons XPS ont été utilisées conjointement pour évaluer avec précision l'épaisseur de couches très minces de SiO$_2$ (20-200 Å) de qualité électronique. Une calibration de l'ellipsométrie et de l'XPS par la METHR a été effectuée. Une procédure de mesure de l'épaisseur absolue d'oxydes fins a été déterminée pour les trois méthodes

Characterization of the epidermal-dermal junction in hiPSC-derived skin organoids

Human induced pluripotent stem cell (hiPSC)-derived hair-bearing skin organoids offer exciting new possibilities for modeling diseases like epidermolysis bullosa (EB). These inherited diseases affect 1 in 30,000 people worldwide and result from perturbed expression and/or structure of components of the epidermal-dermal junction (EDJ). To establish whether hiPSC-derived skin organoids might be able to capture salient features of EB, it is thus important to characterize their EDJ. Here, we report successful generation of hair-bearing skin organoids from two hiPSC lines that exhibited fully stratified interfollicular epidermis. Using immunofluorescence and electron microscopy, we showed that basal keratinocytes in organoids adhere to laminin-332 and type IV collagen-rich basement membrane via type I hemidesmosomes and integrin 81-based adhesion complexes. Importantly, we demonstrated that EDJs in organoids are almost devoid of type VII collagen, a fibril that mediates anchorage of the epidermis to dermis. This should be considered when using skin organoids for EB modeling

Characterization of the epidermal-dermal junction in hiPSC-derived skin organoids

Human induced pluripotent stem cell (hiPSC)-derived hair-bearing skin organoids offer exciting new possibilities for modeling diseases like epidermolysis bullosa (EB). These inherited diseases affect 1 in 30,000 people worldwide and result from perturbed expression and/or structure of components of the epidermal-dermal junction (EDJ). To establish whether hiPSC-derived skin organoids might be able to capture salient features of EB, it is thus important to characterize their EDJ. Here, we report successful generation of hair-bearing skin organoids from two hiPSC lines that exhibited fully stratified interfollicular epidermis. Using immunofluorescence and electron microscopy, we showed that basal keratinocytes in organoids adhere to laminin-332 and type IV collagen-rich basement membrane via type I hemidesmosomes and integrin 81-based adhesion complexes. Importantly, we demonstrated that EDJs in organoids are almost devoid of type VII collagen, a fibril that mediates anchorage of the epidermis to dermis. This should be considered when using skin organoids for EB modeling.Stem cells & developmental biolog

Optical Studies Of Inp/inalas/inp Interface Recombinations

We report on the photoluminescence characterization of a metalorganic vapour phase epitaxy grown InP/InAlAs/InP structure. The energy band alignment of the InAlAs/InP interface is of type II. The PL arising from the first grown interface (InAlAs grown on InP) is clearly seen at 1.2 eV. The localization was possible by scanning the laser beam on a angle-bevelled sample whose bevel crosses all the layers of the InP/InAlAs/InP structure. For the second interface, called the inverse interface (InP grown on InAlAs), a different PL behaviour is observed. The energy of the observed PL peak is 1.3 eV. It is very sensitive to the excitation power. From this behaviour, the Auger depth profiling measurements and the wedge transmission electron microscopy performed on this sample we conclude that this recombination does not originate from a type II interface band structure but from an InAsxP1-x layer located at the inverse interface. This intermediate layer originates from the higher incorporation coefficient of As compared to that of P. © 1993.65-66C777783Quillec, (1990) SPIE's Int. Conf. Aachen, FRGSacilotti, Motisuke, Monteil, Abraham, Iikawa, Montes, Furtado, Waldman, Growth and characterization of type-II/type-I AlGaInAs/InP interfaces (1992) Journal of Crystal Growth, 124, p. 584Kroemer, Griffiths, (1983) IEEE Electron Device Lett., 4 EDL, p. 20Huber, Di Persio, Di Forte-Poisson, Brylinski, Bisaro, Grattepain, Lagorsse, Defect Characterization In InP Epitaxial Layers Grown By LP-MOCVD (1987) Proc. SPIE, 796, p. 182Faist, Ganière, Buffat, Sampson, Reinhart, (1989) J. Appl. Phys., 66, p. 1023Caine, Subbanna, Kroemer, Merz, (1984) Appl. Phys. Lett., 45, p. 1123Brasil, Nahory, Quinn, Tamargo, Farrell, (1992) Appl. Phys. Lett., 60, p. 1981Krawczky, Hollinger, Photoluminescence and x-ray photoelectron spectroscopy measurements of InP surface treated by acid and base solutions (1984) Applied Physics Letters, 45, p. 870Böhrer, Krost, Bimberg, InAsP islands at the lower interface of InGaAs/InP quantum wells grown by metalorganic chemical vapor deposition (1992) Applied Physics Letters, 60, p. 2258Schwedler, Gallmann, Wolter, Kohl, Leo, Kurz, Juillaguet, Baumann, (1993) Appl. Surf. Sci., 63, p. 187Adachi, (1982) J. Appl. Phys., 53, p. 8775Tiwari, Frank, (1992) Appl. Phys. Lett., 60, p. 63

Robust interference management and network design for heterogeneous full-duplex communication networks

Abstract The challenging and diverse design requirements of 5G New Radio open the door for investigating novel solutions targeting enhanced mobile broadband and ultra-reliable low latency communication service classes. This chapter discusses challenges and opportunities of in-band full-duplex communication as a promising solution for next generation radio technologies. Realistic network assumptions are considered. The main challenges relate to self-interference cancellation and the increase of inter/intra-cell interference resulting from simultaneous transmission and reception, as well as the asymmetric nature of network traffic, thus limiting the potential gains in terms of throughput and latency reduction. Particular focus is given to system aspects including the effects on TCP/UDP protocols and symmetric/asymmetric traffic types. We discuss efficient techniques to overcome the challenges of full-duplex communication and propose interference management alternatives such as the virtual full-duplex concept. Up to 70% success probability gains over conventional full-duplex communication can be observed with the proposed virtual full-duplex technique. In addition, we foresee significant benefits and relevance of full-duplex technology in applications other than throughput enhancement and latency reduction, such as relaying, self-backhauling, autonomous device-to-device discovery, and physical layer security

Expression profiling of genes and proteins in HaCaT keratinocytes: proliferating versus differential state.

International audienc

Rhythmic Modulation of the Hematopoietic Niche through Neutrophil Clearance

SummaryUnique among leukocytes, neutrophils follow daily cycles of release from and migration back into the bone marrow, where they are eliminated. Because removal of dying cells generates homeostatic signals, we explored whether neutrophil elimination triggers circadian events in the steady state. Here, we report that the homeostatic clearance of neutrophils provides cues that modulate the physiology of the bone marrow. We identify a population of CD62LLO CXCR4HI neutrophils that have “aged” in the circulation and are eliminated at the end of the resting period in mice. Aged neutrophils infiltrate the bone marrow and promote reductions in the size and function of the hematopoietic niche. Modulation of the niche depends on macrophages and activation of cholesterol-sensing nuclear receptors and is essential for the rhythmic egress of hematopoietic progenitors into the circulation. Our results unveil a process that synchronizes immune and hematopoietic rhythms and expand the ascribed functions of neutrophils beyond inflammation.PaperFlic