Application of novel techniques for interferogram analysis to laser-plasma femtosecond probing

Recently, two novel techniques for the extraction of the phase-shift map (Tomassini {\it et.~al.}, Applied Optics {\bf 40} 35 (2001)) and the electronic density map estimation (Tomassini P. and Giulietti A., Optics Communication {\bf 199}, pp 143-148 (2001)) have been proposed. In this paper we apply both methods to a sample laser-plasma interferogram obtained with femtoseconds probe pulse, in an experimental setup devoted to laser particle acceleration studies.Comment: Submitted to Laser and Particle Beam

FORMULAÇÃO do Método dos Elementos de Contorno para Resolver Problemas de Helmholtz Usando Funções de Interpolação de Base Radial Sem Regularização

O objetivo deste trabalho é propor uma nova formulação para o Método dos Elementos de Contorno denominada aqui como MECID-2 (Método dos Elementos de Contorno com Integração Direta sem Regularização), que faz uso das funções de base radial para aproximar integrais de domínio, mas que possui uma estratégia de solução diferente do modelo apresentado na formulação já validada com êxito, a MECID Regularizada. Foram propostos cinco problemas governados pela Equação de Helmholtz para a validação desta formulação em que os resultados da MECID-2 foram comparados com a MECID Regularizada, tomando como parâmetro a solução analítica do problema, quando houver, ou a solução aproximada pelo Método dos Elementos Finitos (MEF). Outro parâmetro importante avaliado nos resultados é a importância do refinamento da malha de contorno e da quantidade de pontos internos inseridos no domínio. São geradas curvas de desempenho através do cálculo do erro médio percentual para cada malha, demonstrando a convergência e a precisão de cada método

Dynamics of charge-displacement channeling in intense laser-plasma interactions

The dynamics of transient electric fields generated by the interaction of high intensity laser pulses with underdense plasmas has been studied experimentally with the proton projection imaging technique. The formation of a charged channel, the propagation of its front edge and the late electric field evolution have been characterised with high temporal and spatial resolution. Particle-in-cell simulations and an electrostatic, ponderomotive model reproduce the experimental features and trace them back to the ponderomotive expulsion of electrons and the subsequent ion acceleration.Comment: 5 figures, accepted for publication in New Journal of Physic

Analysis of space-resolved X-ray spectra from laser plasmas

High dynamic range, space-resolved X-ray spectra, obtained using a TlAP crystal and a cooled CCD camera as a detector, were used to investigate the electron density and temperature profiles of an aluminum laser plasma with micrometer resolution. The electron density profile retrieved from the measurements is compared with numerical predictions from the two hydrodynamics codes MEDUSA (1D) and POLLUX (2D). It is shown that 2D density profiles can be successfully reproduced by 1D simulations using a spherical geometry with an ad hoc initial radius, leading to similar electron temperature profiles

An original deconvolution approach for oil production allocation based on geochemical fingerprinting

We tackle oil commingling scenarios and develop an original deconvolution approach for geochemical production allocation. This yields robust assessment of the proportions of oils forming a mixture originating from commingling oils associated with diverse reservoirs or, wells. Our study starts from considering that production allocation performed by means of geochemical fingerprinting is relevant in the context of modern and sustainable use of georesources, with the added benefit of favoring shared facilities and production equipment. A geochemical production allocation workflow is typically structured according to two steps: (i) determination of the chromatograms associated with the mixture (and eventually with each of the End Members, EMs, constituting the fluids in the mixture), and (ii) the use of a deconvolution algorithm to estimate the mass fraction of each EM. Concerning the latter step, we introduce an original approach and the ensuing deconvolution algorithm (hereafter termed PGM) that does not require additional laboratory efforts in comparison with traditional approaches. We also present extensions of widely used deconvolution algorithms, which we frame in a (stochastic) Monte Carlo context to improve their robustness and reliability. The new PGM approach is assessed jointly with a suite of typically used approaches and algorithms against new laboratory-based commingling scenarios. The latter are based on the design and introduction of a novel and low-cost experimental method. The results of the study (i) constitute a unique and rigorous comparison of the traditionally employed production allocation deconvolution algorithms, (ii) document the critical importance of the number of features of the chromatograms used during a quantitative deconvolution, and (iii) suggest that our new PGM approach is very robust and accurate compared to existing approaches

Corneal involvement in rheumatoid arthritis: an vivo confocal study

PURPOSE. To analyze the in vivo morphology of corneal cells and nerves in patients with rheumatoid arthritis (RA), with or without secondary Sj\uf6gren\u2019s syndrome (SSII), and to investigate the correlations between corneal alterations and RA activity. METHODS. Fifty patients with RA and 30 age- and gender-matched control subjects were studied. SSII was diagnosed according to the American-European Consensus Group criteria, and RA activity was evaluated by the Lansbury index (LI). Confocal microscopy was used to investigate corneal thickness, the number of epithelial and stromal cells, and keratocyte hyperreflectivity. In addition, the sub-basal plexus was assessed for the number, tortuosity, and reflectivity of the nerve fibers and the presence of beadlike formations. RESULTS. Sixteen percent of patients with RA also had SSII. Between the SSII and non-SSII groups, no significant differences were found in the LI or in the clinical and confocal variables. Significant differences were present between patients with RA and control subjects for all the variables studied except nerve reflectivity. In patients with RA with and without SSII, LI correlated significantly with the number of beadlike formations and the number of hyperreflective, activated keratocytes. CONCLUSIONS. Confocal microscopy of patients with RA showed several changes in corneal cells and nerves. The number of beadlike formations and the number of activated keratocytes could be interpreted as confocal signs of ocular surface disease activity. These correlations with the index of systemic disease activity, LI, may provide insight regarding the pathogenic mechanisms of dry eye in patients with RA

Line spectroscopy with spatial resolution of laser-plasma X-ray emission

High dynamic range, space-resolved X-ray spectra of an aluminum laser–plasma in the 5.5–8 Å range were obtained using a TlAP crystal and a cooled CCD camera as a detector. This technique was used to investigate the emission region in the longitudinal direction over a distance of approximately 350 μm from the solid target surface. These data show that the electron density profile varies by two orders of magnitude with the temperature ranging from about 180 eV in the overdense region to about 650 eV in the underdense region. Accordingly, different equilibria take place across the explored region which can be identified with this experimental technique. Detailed studies on highly ionized atomic species in different plasma conditions can therefore be performed simultaneously under controlled conditions

Costruire la memoria: uso e abuso della storia fra tarda repubblica e primo principato.

Il volume, che raccoglie gli atti del Convegno Interazionale "Costruire la memoria: uso e abuso della storia fra tarda repubblica e primo principato" svoltosi a Venezia il 14 e il 15 gennaio 2016, indaga, attraverso casi individuati dai contributori, come la ricostruzione della storia tardo repubblicana e della prima età imperiale nelle fonti sia oggetto di manipolazioni diverse per tipologia, finalità, esiti; origini tradizioni contrastanti su molti momenti del passato e si traduca in un importante strumento della politica. Il Convegno, di cui il volume pubblica i contributi, ha rappresentato il terzo appuntamento congressuale (dopo le esperienze del 2010 e del 2013) organizzato dal gruppo di ricerca "Fra repubblica e principato", diretto da R. Cristofoli, A. Galimberti e F. Rohr Vio, che si propone di indagare l storia del I secolo a.C.-I secolo d.C. mediante il coinvolgimento di specialisti che consentano l'impostazione di studi interdisciplinari di respiro internazionale

Salivary biomarkers of neurodegenerative and demyelinating diseases and biosensors for their detection

Salivary analysis is gaining increasing interest as a novel and promising field of research for the diagnosis of neurodegenerative and demyelinating diseases related to aging. The collection of saliva offers several advantages, being noninvasive, stress-free, and repeatable. Moreover, the detection of biomarkers directly in saliva could allow an early diagnosis of the disease, leading to timely treatments. The aim of this manuscript is to highlight the most relevant researchers’ findings relatively to salivary biomarkers of neurodegenerative and demyelinating diseases, and to describe innovative and advanced biosensing strategies for the detection of salivary biomarkers. This review is focused on five relevant aging-related neurodegenerative disorders (Alzheimer's disease, Parkinson's disease, Amyotrophic Lateral Sclerosis, Huntington's disease, Multiple Sclerosis) and the salivary biomarkers most commonly associated with them. Advanced biosensors enabling molecular diagnostics for the detection of salivary biomarkers are presented, in order to stimulate future research in this direction and pave the way for their clinical application