Faceted anomalous scaling in the epitaxial growth of semiconductor films

We apply the generic dynamical scaling theory (GDST) to the surfaces of CdTe polycrystalline films grown in glass substrates. The analysed data were obtained with a stylus profiler with an estimated resolution lateral resolution of $l_c=0.3 \mu$m. Both real two-point correlation function and power spectrum analyses were done. We found that the GDST applied to the surface power spectra foresees faceted morphology in contrast with the self-affine surface indicated by the local roughness exponent found via the height-height correlation function. This inconsistency is explained in terms of convolution effects resulting from the finite size of the probe tip used to scan the surfaces. High resolution AFM images corroborates the predictions of GDST.Comment: to appear in Europhysics Letter

Partner selection in indoor-to-outdoor cooperative networks: an experimental study

In this paper, we develop a partner selection protocol for enhancing the network lifetime in cooperative wireless networks. The case-study is the cooperative relayed transmission from fixed indoor nodes to a common outdoor access point. A stochastic bivariate model for the spatial distribution of the fading parameters that govern the link performance, namely the Rician K-factor and the path-loss, is proposed and validated by means of real channel measurements. The partner selection protocol is based on the real-time estimation of a function of these fading parameters, i.e., the coding gain. To reduce the complexity of the link quality assessment, a Bayesian approach is proposed that uses the site-specific bivariate model as a-priori information for the coding gain estimation. This link quality estimator allows network lifetime gains almost as if all K-factor values were known. Furthermore, it suits IEEE 802.15.4 compliant networks as it efficiently exploits the information acquired from the receiver signal strength indicator. Extensive numerical results highlight the trade-off between complexity, robustness to model mismatches and network lifetime performance. We show for instance that infrequent updates of the site-specific model through K-factor estimation over a subset of links are sufficient to at least double the network lifetime with respect to existing algorithms based on path loss information only.Comment: This work has been submitted to IEEE Journal on Selected Areas in Communications in August 201

Refractive elastic scattering of carbon and oxygen nuclei: The mean field analysis and Airy structures

The experimental data on the $^{16}$O$+^{12}$C and $^{18}$O$+^{12}$C elastic scatterings and their optical model analysis are presented. Detailed and complete elastic angular distributions have been measured at the Strasbourg Vivitron accelerator at several energies covering the energy range between 5 and 10 MeV per nucleon. The elastic scattering angular distributions show the usual diffraction pattern and also, at larger angles, refractive effects in the form of nuclear rainbow and associated Airy structures. The optical model analysis unambiguously shows the evolution of the refractive scattering pattern. The observed structure, namely the Airy minima, can be consistently described by a nucleus-nucleus potential with a deep real part and a weakly absorptive imaginary part. The difference in absorption in the two systems is explained by an increased imaginary (mostly surface) part of the potential in the $^{18}$O$+^{12}$C system. The relation between the obtained potentials and those reported for the symmetrical $^{16}$O$+^{16}$O and $^{12}$C$+^{12}$C systems is drawn.Comment: 10 pages, 9 figures, Phys. rev. C in pres

Dynamical Renormalization Group Study for a Class of Non-local Interface Equations

We provide a detailed Dynamic Renormalization Group study for a class of stochastic equations that describe non-conserved interface growth mediated by non-local interactions. We consider explicitly both the morphologically stable case, and the less studied case in which pattern formation occurs, for which flat surfaces are linearly unstable to periodic perturbations. We show that the latter leads to non-trivial scaling behavior in an appropriate parameter range when combined with the Kardar-Parisi-Zhang (KPZ) non-linearity, that nevertheless does not correspond to the KPZ universality class. This novel asymptotic behavior is characterized by two scaling laws that fix the critical exponents to dimension-independent values, that agree with previous reports from numerical simulations and experimental systems. We show that the precise form of the linear stabilizing terms does not modify the hydrodynamic behavior of these equations. One of the scaling laws, usually associated with Galilean invariance, is shown to derive from a vertex cancellation that occurs (at least to one loop order) for any choice of linear terms in the equation of motion and is independent on the morphological stability of the surface, hence generalizing this well-known property of the KPZ equation. Moreover, the argument carries over to other systems like the Lai-Das Sarma-Villain equation, in which vertex cancellation is known {\em not to} imply an associated symmetry of the equation.Comment: 34 pages, 9 figures. Journal of Statistical Mechanics: Theory and Experiments (in press

Therapeutics and carriers: The dual role of proteins in nanoparticles for ocular delivery

© 2015 Bentham Science Publishers. Blindness and visual impairment affect millions of people worldwide and have a very important impact on patients quality of life. Proteins and peptides represent nowadays an important therapeutic tool for the treatment of ocular diseases but, despite their potential, have significant limitations, as the administration of protein-based pharmaceuticals represents a real challenge. Moreover, administration of ocular medications is difficult due to the peculiar structure of this organ and the presence of numerous barriers protecting the eye inner structure. Nanoencapsulation of peptides and proteins presents a number of advantages for their ocular delivery since it can protect the drug from metabolic activity, control and sustain the release and increase drug bioavailability after topical or intravitreal administration. In fact, nanoparticulate formulations are contributing to overcome ocular barriers, such as the corneal or the blood-retinal barrier, improve the residence time in the eye, increase local drug level, reduce the drug dosage and showing improved performance when compared to conventional formulations. Besides, proteins have also been proposed for the preparation of nanocarriers intended for ophthalmic administration, since they are highly biocompatible, biodegradable and easily modified to link surface ligands. The present review focuses the attention on the use of proteins in ocular drug delivery nanotechnology: their dual role as both therapeutics and carriers has been critically evaluated and discussed

Impact of high-pressure carbon dioxide on polyphenoloxidase activity and stability of fresh apple juice

Freshly-extracted apple juice was exposed to high pressure carbon dioxide (HP-CO2) treatment at 20, 35 and 45 °C at different pressure conditions (6.0, 12.0 and 18.0 MPa) for up to 30 min. Samples were analysed for residual enzymatic activity. The time needed for 90% enzyme inactivation (Dp) decreased when CO2 pressure increased, while the CO2 pressure sensitivity of the enzyme (zp) showed no variation with temperature. The HP-CO2 treatment at 12 MPa and 35 °C allowed the minimum residual enzyme activity (20%) to be reached in 10 min. Samples treated under these conditions showed lower polyphenoloxidase activity and higher microbial stability than untreated apple juice while presenting a sensory fresh-likelihood higher than thermally pasteurized apple juice. © 2016 Elsevier Lt

Cooperative Regions For Coded Cooperation Over Time-Varying Fading Channels

The performance analysis of coded cooperation has been mainly focused on two extreme cases of channel variability, i.e. the block-fading (BF) and the fast-fading (FF) model. In more practical propagation environments the fading correlation across time depends on the level of user mobility. This paper analyzes the effects of time-selective fading on the performance of coded cooperation by providing an analytical framework for the error rate evaluation as a function of the mobility degree of the mobile station (MS) and of the quality of the inter-MS channel. The purpose is to evaluate the conditions on the propagation settings where the additional exploitation of spatial diversity (when time-diversity is available) provided by cooperative transmission is able to enhance substantially the performance of the non-cooperative transmission. We show that coded cooperation can outperform the non-cooperative (coded and bit-interleaved) transmission only up to a certain degree of mobility. The cooperative region is defined as the collection of mobility settings for which coded cooperation can be regarded as a competitive strategy compared to non-cooperative transmission. Contrary to what has been previously shown for BF channels, we demonstrate that the inter-MS channel quality plays a key role in the definition of the cooperative region

Mammalian tumor xenografts induce neovascularization in zebrafish embryos.

The zebrafish (Danio rerio)/tumor xenograft model represents a powerful new model system in cancer. Here, we describe a novel exploitation of the zebrafish model to investigate tumor angiogenesis, a pivotal step in cancer progression and target for antitumor therapies. Human and murine tumor cell lines that express the angiogenic fibroblast growth factor (FGF) 2 and/or vascular endothelial growth factor (VEGF) induce the rapid formation of a new microvasculature when grafted close to the developing subintestinal vessels of zebrafish embryos at 48 h postfertilization. Instead, no angiogenic response was exerted by related cell clones defective in the production of these angiogenic growth factors. The newly formed blood vessels sprout from the subintestinal plexus of the zebrafish embryo, penetrate the tumor graft, and express the transcripts for the zebrafish orthologues of the early endothelial markers Fli-1, VEGF receptor-2 (VEGFR2/KDR), and VE-cadherin. Accordingly, green fluorescent protein–positive neovessels infiltrate the graft when tumor cells are injected in transgenic VEGFR2:G-RCFP zebrafish embryos that express green fluorescent protein under the control of the VEGFR2/KDR promoter. Systemic exposure of zebrafish embryos immediately after tumor cell injection to prototypic antiangiogenic inhibitors, including the FGF receptor tyrosine kinase inhibitor SU5402 and the VEGFR2/KDR tyrosine kinase inhibitor SU5416, suppresses tumor-induced angiogenesis without affecting normal blood vessel development. Accordingly, VE-cadherin gene inactivation by antisense morpholino oligonucleotide injection inhibits tumor neovascularization without affecting the development of intersegmental and subintestinal vessels. These data show that the zebrafish/ tumor xenograft model represents a novel tool for investigating the neovascularization process exploitable for drug discovery and gene targeting in tumor angiogenesis