A Recursive approach to the matrix moment problem

In this paper, we study the truncated matrix moment problem in one variable through recursive matrix extensions. \ We give necessary and sufficient conditions for a recursive matrix extension of finite data to be a matrix moment sequence in the classical cases of Hamburger, Stieltjes, and Hausdorff moment problems. \ We also discuss matricial subnormal completion and matricial $k$--hyponormal completion problems and provide an analog of Stampfli's Theorem on flat propagation for $2$--hyponormal matricial weighted shifts.Comment: 27 page

Structural and chemical properties of RF sputtered a-C/WOx bilayers

Amorphous carbon on tungsten oxide (a-C/WOx) bilayers were deposited, on glass and silicon substrates, by radio-frequency (RF) sputtering. The WOx layers are obtained from a pure tungsten target in a mixture of argon and oxygen while the a-C ones were obtained from a pure graphite target in a pure argon plasma. The structural and chemical properties of the a-C/WOx interface were investigated by Grazing Incidence X-Ray Diffraction (GIXRD), X-Ray Reflectometry (XRR) and Electron Dispersive Analysis of X-Ray (EDAX). The XRR spectra show that the a-C/WOx interface is strongly reactive, for high RF powers, with the formation of an inhomogeneous WOxCy total layer. The density of this layer is much smaller than the WOx one. For low RF powers, the a-C/WOx interface is also reactive and the total layer obtained is inhomogeneous in depth but the W atoms content in the top layer is relatively small. This result is also confirmed by the EDAX analyses. The GIXRD spectra show that the WOx layers are crystallized while there is no formation of crystallized tungsten carbides or oxycarbides.Amorphous carbon on tungsten oxide (a-C/WOx) bilayers were deposited, on glass and silicon substrates, by radio-frequency (RF) sputtering. The WOx layers are obtained from a pure tungsten target in a mixture of argon and oxygen while the a-C ones were obtained from a pure graphite target in a pure argon plasma. The structural and chemical properties of the a-C/WOx interface were investigated by Grazing Incidence X-Ray Diffraction (GIXRD), X-Ray Reflectometry (XRR) and Electron Dispersive Analysis of X-Ray (EDAX). The XRR spectra show that the a-C/WOx interface is strongly reactive, for high RF powers, with the formation of an inhomogeneous WOxCy total layer. The density of this layer is much smaller than the WOx one. For low RF powers, the a-C/WOx interface is also reactive and the total layer obtained is inhomogeneous in depth but the W atoms content in the top layer is relatively small. This result is also confirmed by the EDAX analyses. The GIXRD spectra show that the WOx layers are crystallized while there is no formation of crystallized tungsten carbides or oxycarbides

Proton conductivity in Al-stevensite pillared clays

Fine stevensite mineral fraction (< 2 m) has been extracted from natural Moroccan ghassoulite clay. Thereafter, it has been pillared by Al13 polycations species. Physico-chemical characterization, performed using X-ray diffraction (XRD), thermal analysis (TG-TDA) and Scanning Electron Microscopy (SEM) equipped with X-ray Energy Dispersion (XED) analysis, has proved that stevensite pillaring has been successfully achieved. Electrical impedance measurements, carried out onto samples before and after pillaring operation, have shown an increase in proton conductivity for pillared with respect to pristine stevensite clay mineral.Fine stevensite mineral fraction (< 2 m) has been extracted from natural Moroccan ghassoulite clay. Thereafter, it has been pillared by Al13 polycations species. Physico-chemical characterization, performed using X-ray diffraction (XRD), thermal analysis (TG-TDA) and Scanning Electron Microscopy (SEM) equipped with X-ray Energy Dispersion (XED) analysis, has proved that stevensite pillaring has been successfully achieved. Electrical impedance measurements, carried out onto samples before and after pillaring operation, have shown an increase in proton conductivity for pillared with respect to pristine stevensite clay mineral

Characterization of CuInTe2 thin films prepared by flash evaporation

peer reviewedThin films of CuInTe2 were grown by flash evaporation. The influence of the substrate temperature Ts during film deposition on the properties of the thin films was examined. CuInTe2 films were structurally characterized by the grazing incidence x-ray diffraction (GIXD) technique. Investigation by this technique demonstrates that the surface of thin films of CuInTe2 prepared by flash vaporation at Ts > 100 °C exhibits the chalcopyrite structure with additional binary compounds in the surface. However, in the volume the films exhibit the chalcopyrite structure only; no foreign phases were observed. X-ray reflectometry was utilized to evaluate the critical reflection angle bc of CuInTe2 (bCuInTe2 c 0.32°) which permitted us to calculate the density of the films to be 6 g cm−3. The evaporated films were p type and the films deposited at Ts = 100 °C had a resistivity in the range 0.3–2 cm. From optical measurements we have determined the optical energy gap Eg 0.94 eV and the effective reduced mass m*r 0.07me

Finite temperature stability and dimensional crossover of exotic superfluidity in lattices

We investigate exotic paired states of spin-imbalanced Fermi gases in anisotropic lattices, tuning the dimension between one and three. We calculate the finite temperature phase diagram of the system using real-space dynamical mean-field theory in combination with the quantum Monte Carlo method. We find that regardless of the intermediate dimensions examined, the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state survives to reach about one third of the BCS critical temperature of the spin-density balanced case. We show how the gapless nature of the state found is reflected in the local spectral function. While the FFLO state is found at a wide range of polarizations at low temperatures across the dimensional crossover, with increasing temperature we find out strongly dimensionality-dependent melting characteristics of shell structures related to harmonic confinement. Moreover, we show that intermediate dimension can help to stabilize an extremely uniform finite temperature FFLO state despite the presence of harmonic confinement.Comment: 5 pages, 3 figure

Transcriptomics reveal an integrative role for maternal thyroid hormones during zebrafish embryogenesis

Thyroid hormones (THs) are essential for embryonic brain development but the genetic mechanisms involved in the action of maternal THs (MTHs) are still largely unknown. As the basis for understanding the underlying genetic mechanisms of MTHs regulation we used an established zebrafish monocarboxylic acid transporter 8 (MCT8) knock-down model and characterised the transcriptome in 25hpf zebrafish embryos. Subsequent mapping of differentially expressed genes using Reactome pathway analysis together with in situ expression analysis and immunohistochemistry revealed the genetic networks and cells under MTHs regulation during zebrafish embryogenesis. We found 4,343 differentially expressed genes and the Reactome pathway analysis revealed that TH is involved in 1681 of these pathways. MTHs regulated the expression of core developmental pathways, such as NOTCH and WNT in a cell specific context. The cellular distribution of neural MTH-target genes demonstrated their cell specific action on neural stem cells and differentiated neuron classes. Taken together our data show that MTHs have a role in zebrafish neurogenesis and suggest they may be involved in cross talk between key pathways in neural development. Given that the observed MCT8 zebrafish knockdown phenotype resembles the symptoms in human patients with Allan-Herndon-Dudley syndrome our data open a window into understanding the genetics of this human congenital condition.Portuguese Fundacao para Ciencia e Tecnologia (FCT) [PTDC/EXPL/MARBIO/0430/2013]; CCMAR FCT Plurianual financing [UID/Multi/04326/2013]; FCT [SFRH/BD/111226/2015, SFRH/BD/108842/2015, SFRH/BPD/89889/2012]; FCT-IF Starting Grant [IF/01274/2014]info:eu-repo/semantics/publishedVersio