Robust Phase Unwrapping by Convex Optimization

The 2-D phase unwrapping problem aims at retrieving a "phase" image from its modulo $2\pi$ observations. Many applications, such as interferometry or synthetic aperture radar imaging, are concerned by this problem since they proceed by recording complex or modulated data from which a "wrapped" phase is extracted. Although 1-D phase unwrapping is trivial, a challenge remains in higher dimensions to overcome two common problems: noise and discontinuities in the true phase image. In contrast to state-of-the-art techniques, this work aims at simultaneously unwrap and denoise the phase image. We propose a robust convex optimization approach that enforces data fidelity constraints expressed in the corrupted phase derivative domain while promoting a sparse phase prior. The resulting optimization problem is solved by the Chambolle-Pock primal-dual scheme. We show that under different observation noise levels, our approach compares favorably to those that perform the unwrapping and denoising in two separate steps.Comment: 6 pages, 4 figures, submitted in ICIP1

Non-parametric PSF estimation from celestial transit solar images using blind deconvolution

Context: Characterization of instrumental effects in astronomical imaging is important in order to extract accurate physical information from the observations. The measured image in a real optical instrument is usually represented by the convolution of an ideal image with a Point Spread Function (PSF). Additionally, the image acquisition process is also contaminated by other sources of noise (read-out, photon-counting). The problem of estimating both the PSF and a denoised image is called blind deconvolution and is ill-posed. Aims: We propose a blind deconvolution scheme that relies on image regularization. Contrarily to most methods presented in the literature, our method does not assume a parametric model of the PSF and can thus be applied to any telescope. Methods: Our scheme uses a wavelet analysis prior model on the image and weak assumptions on the PSF. We use observations from a celestial transit, where the occulting body can be assumed to be a black disk. These constraints allow us to retain meaningful solutions for the filter and the image, eliminating trivial, translated and interchanged solutions. Under an additive Gaussian noise assumption, they also enforce noise canceling and avoid reconstruction artifacts by promoting the whiteness of the residual between the blurred observations and the cleaned data. Results: Our method is applied to synthetic and experimental data. The PSF is estimated for the SECCHI/EUVI instrument using the 2007 Lunar transit, and for SDO/AIA using the 2012 Venus transit. Results show that the proposed non-parametric blind deconvolution method is able to estimate the core of the PSF with a similar quality to parametric methods proposed in the literature. We also show that, if these parametric estimations are incorporated in the acquisition model, the resulting PSF outperforms both the parametric and non-parametric methods.Comment: 31 pages, 47 figure

Understanding the process of envelope glycoprotein incorporation into virions in simian and feline immunodeficiency viruses

The lentiviral envelope glycoproteins (Env) mediate virus entry by interacting with specific receptors present at the cell surface, thereby determining viral tropism and pathogenesis. Therefore, Env incorporation into the virions formed by assembly of the viral Gag polyprotein at the plasma membrane of the infected cells is a key step in the replication cycle of lentiviruses. Besides being useful models of human immunodeficiency virus (HIV) infections in humans and valuable tools for developing AIDS therapies and vaccines, simian and feline immunodeficiency viruses (SIV and FIV, respectively) are relevant animal retroviruses; the study of which provides important information on how lentiviral replication strategies have evolved. In this review, we discuss the molecular mechanisms underlying the incorporation of the SIV and FIV Env glycoproteins into viral particles.Fil: Affranchino, Jose Luis. Universidad de Belgrano. Facultad de Ciencias Exactas y Naturales. Laboratorio de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gonzalez, Silvia Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Belgrano. Facultad de Ciencias Exactas y Naturales. Laboratorio de Virología; Argentin

Courtship plasticity reveals the evolution of dialects in allopatric fish populations

Traditionally, reproductive isolation between disjoint populations has been thought to emerge as a result of the accumulation of different mutations, genetic drift, or through the effects of natural and sexual selection^1^. Alternatively, the ability of an organism to express different phenotypes depending on the environment (i.e. phenotypic plasticity) could produce reproductive isolation^2,3^. Sexually selected traits are expected to be phenotypically plastic and can result in modifications of the species recognition system and thus originate new species^4^. Here we show that the population-characteristic male courtship behaviour of a fish (Girardinichthys multiradiatus) is modified in the presence of females from other populations, that this is due to the males responding to subtle cues from females, and that they fail to emulate the female's population-characteristic behaviour. We conclude that plasticity has led to the creation of local dialects in the courtship pattern that hampers communication between heterogametic individuals and promotes pre-mating isolation

Funtional characterization of a large genomic deletion resulting in loss of virulence in Ralstonia solanacearum race3 biovar2 strains

Les souches de Ralstonia solanacearum dites 'race 3 biovar 2' sont les agents responsables de la maladie de la pourriture noire de la pomme de terre, une maladie dévastatrice dans les régions intertropicales et émergente en Europe. Par une analyse de génomique comparative, nous avons identifié chez la souche IPO1609 une délétion génomique de 77 kilobases entrainant une perte quasi-complète de virulence chez la souche IPO1609. La caractérisation fonctionnelle de cette région delétée a permis d'identifier deux loci majeurs contribuant à la virulence de la souche IPO1609: deux gènes de la voie de biosynthèse de la méthionine, metER, et des gènes vraisemblablement impliqués dans la biosynthèse d'auxine. L'expression des gènes metER est dépendante du régulateur central de la pathogénie HrpG. Un mutant metER n'est pas auxotrophe mais est significativement atténué en virulence, démontrant ainsi un premier lien direct entre le métabolisme de la méthionine et la pathogénie de R. solanacearum.Ralstonia solanacearum is one of the most devastating plant pathogen worldwide. Through a comparative genomic analysis between R. solanacearum 'race3 biovar 2' strains, the causal agent of potato brown rot, we identified a 77kb region which is absent in the hypovirulent strain IPO1609. We proved that IPO1609 indeed carries a 77kb genomic deletion and we provide genetic evidence that presence of this deletion is responsible for almost complete loss of pathogenicity of this strain. We identified two loci having a major contribution to IPO1609 pathogenesis: the methionine biosynthesis genes metER and a gene cluster putatively involved in the biosynthesis of the phytohormone auxin. Expression of metER is controlled by the pathogenicity regulator HrpG, and the finding that a metER mutant is not auxotrophic but is significantly reduced in virulence provides the first direct link between methionine metabolism and pathogenicity in R. solanacearum

Connotations of ephemeral spaces of consumption: a case study of Singapore’s Little India

The practice of consumption is intrinsically integrated into our post-modern society and is fundamental in exercising, defining and re-defining people and group identity. Consumption occurs somewhere and somewhen it is a spatial activity, it is shaped by time and space. The site of this investigation, the touristic enclave of Little India, appears to hold a “distinct” culture of consumption within Singapore and ephemeral spaces of consumption that are continuously produced and re-produced everyday and every night seem to be essential for the distinctive behavior of consumers. This case study analyzes the processes of production, de-production, reproduction of the mentioned temporary spaces of consumption and their significance for a multicultural/multiethnic society.Peer Reviewe

Anatomía foliar de especies arbóreas del Chaco húmedo

En este trabajo se presentan los estudios de la anatomía foliar de especies arbóreas que crecen en el Chaco húmedo, que ocupa aproximadamente la mitad oriental de Formosa y Chaco, la parte norte de Santa Fe y el noroeste de Corrientes, Argentina. La vegetación de esta área es polimorfa: bosques xerófilos, en galería, estepas arbustivas, palmares, sabanas, praderas, pajonales, etc. Los montes están integrados, en buena medida, por especies que se caracterizan por un crecimiento lento, por poseer maderas duras y semiduras y por su contenido en tanino. Esta misma característica ha sido la que originó la histórica y actual depredacióN sobre maderas de mayor valor económico. Este estudio se realizó a fin de determinar la anatomía de las hojas de 39 especies arbóreas del Chaco Húmedo y analizar la relación entre las estructuras anatómicas y los diversos factores ambientales que caracterizan a una región. La mayoría de las especies estudiadas presentan uno o varios caracteres, que combinados, permiten su identificación. Cuando se analizan las características discriminando entre el tipo de comunidad donde crece, no se encontraron diferencias notables entre aquellas que habitan las selvas en galería o los bosques xerófilos.Fil: Gonzalez, Adriana B.. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias; ArgentinaFil: Gonzalez, Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); Argentin

Connotations of ephemeral spaces of consumption: a case study of Singapore’s Little India

The practice of consumption is intrinsically integrated into our post-modern society and is fundamental in exercising, defining and re-defining people and group identity. Consumption occurs somewhere and somewhen it is a spatial activity, it is shaped by time and space. The site of this investigation, the touristic enclave of Little India, appears to hold a “distinct” culture of consumption within Singapore and ephemeral spaces of consumption that are continuously produced and re-produced everyday and every night seem to be essential for the distinctive behavior of consumers. This case study analyzes the processes of production, de-production, reproduction of the mentioned temporary spaces of consumption and their significance for a multicultural/multiethnic society.Peer Reviewe

The Drive to Create an Assessment Plan: A Department Head\u27s Roadmap

In an effort to become a data-driven department, the Head of Faculty and Graduate Services, in collaboration with the Office of Library Planning & Assessment, introduced a strategy for developing an assessment plan to instill a culture of assessment in the department; help team members gain confidence in the practice; and effectively utilize in-house resources to create a practical approach to assessment. A three-prong approach is proposed. Destination: Instill a culture of assessment by demonstrating to the team that assessment can be applied on an everyday level, and can lead to effective decision making. Route: Team members participate in a simple assessment project that gives actionable results quickly. A case study will be discussed. Destination: Help team members gain confidence in assessment. Route: Give team members a strong foundation in the various areas of assessment by inviting experts to conduct training. The goal is to equip members with the ability to ask the right questions, and develop their own basic tool boxes. Destination: Effectively utilize in-house resources. Route: Collaborate closely with the Office of Library Planning and Assessment to develop a systematic consulting service for the team. This presentation will be a progress report of the implementation of this roadmap