Power-law decay in first-order relaxation processes

Starting from a simple definition of stationary regime in first-order relaxation processes, we obtain that experimental results are to be fitted to a power-law when approaching the stationary limit. On the basis of this result we propose a graphical representation that allows the discrimination between power-law and stretched exponential time decays. Examples of fittings of magnetic, dielectric and simulated relaxation data support the results.Comment: to appear in Phys. Rev. B; 4 figure

Fast maximum likelihood estimation via equilibrium expectation for large network data

This is the final version. Available from the publisher via the DOI in this record.A major line of contemporary research on complex networks is based on the development of statistical models that specify the local motifs associated with macro-structural properties observed in actual networks. This statistical approach becomes increasingly problematic as network size increases. In the context of current research on efficient estimation of models for large network data sets, we propose a fast algorithm for maximum likelihood estimation (MLE) that affords a significant increase in the size of networks amenable to direct empirical analysis. The algorithm we propose in this paper relies on properties of Markov chains at equilibrium, and for this reason it is called equilibrium expectation (EE). We demonstrate the performance of the EE algorithm in the context of exponential random graph models (ERGMs) a family of statistical models commonly used in empirical research based on network data observed at a single period in time. Thus far, the lack of efficient computational strategies has limited the empirical scope of ERGMs to relatively small networks with a few thousand nodes. The approach we propose allows a dramatic increase in the size of networks that may be analyzed using ERGMs. This is illustrated in an analysis of several biological networks and one social network with 104,103 nodes.Swiss National Science Foundatio

Characterization of self-injected electron beams from LWFA experiments at SPARC_LAB

The plasma-based acceleration is an encouraging technique to overcome the limits of the accelerating gradient in the conventional RF acceleration. A plasma accelerator is able to provide accelerating fields up to hundreds of $GeV/m$, paving the way to accelerate particles to several MeV over a short distance (below the millimetre range). Here the characteristics of preliminary electron beams obtained with the self-injection mechanism produced with the FLAME high-power laser at the SPARC_LAB test facility are shown. In detail, with an energy laser on focus of $1.5\ J$ and a pulse temporal length (FWHM) of $40\ fs$, we obtained an electron plasma density due to laser ionization of about $6 \times 10^{18}\ cm^{-3}$, electron energy up to $350\ MeV$ and beam charge in the range $(50 - 100)\ pC$.Comment: 6 pages, 11 figures, conference EAAC201

A Bayesian parameter estimation approach to pulsar time-of-arrival analysis

The increasing sensitivities of pulsar timing arrays to ultra-low frequency (nHz) gravitational waves promises to achieve direct gravitational wave detection within the next 5-10 years. While there are many parallel efforts being made in the improvement of telescope sensitivity, the detection of stable millisecond pulsars and the improvement of the timing software, there are reasons to believe that the methods used to accurately determine the time-of-arrival (TOA) of pulses from radio pulsars can be improved upon. More specifically, the determination of the uncertainties on these TOAs, which strongly affect the ability to detect GWs through pulsar timing, may be unreliable. We propose two Bayesian methods for the generation of pulsar TOAs starting from pulsar "search-mode" data and pre-folded data. These methods are applied to simulated toy-model examples and in this initial work we focus on the issue of uncertainties in the folding period. The final results of our analysis are expressed in the form of posterior probability distributions on the signal parameters (including the TOA) from a single observation.Comment: 16 pages, 4 figure

Online positive interventions to promote well-being and resilience in the adolescent population: A narrative review

Numerous studies have shown an alarming prevalence of depression, anxiety, and behavior disorders in youth. Thus, prevention of psychological problems in this population becomes crucial. According to the World Health Organization (1), prevention should also include the promotion and development of the individual''s strengths in order to reduce vulnerability to suffering from mental disorders. In addition, other key elements of prevention are the reach, adoption, implementation, and maintenance of interventions. The information and communication technologies, especially the Internet, have much to offer in terms of the prevention and promotion of positive mental health in adolescents. This paper reviews these fields of research-prevention, positive psychology, Internet, and adolescents-and discusses the potential of positive interventions delivered over the Internet as effective and sustainable health promotion tools. The paper provides a brief description of the systems developed so far and a summary of selected features of the studies detected in the literature review. The overall conclusions are that there is a need for more controlled studies with long-term follow-ups, the interventions should be designed considering the specific features of the target users and the specific contexts where the interventions will be delivered, and they could be enhanced by the use of other technologies, such as smartphones, sensors, or social networks

Building an end user focused THz based ultra high bandwidth wireless access network: The TERAPOD approach

The TERAPOD project aims to investigate and demonstrate the feasibility of ultra high bandwidth wireless access networks operating in the Terahertz (THz) band. The proposed TERAPOD THz communication system will be developed, driven by end user usage scenario requirements and will be demonstrated within a first adopter operational setting of a Data Centre. In this article, we define the full communications stack approach that will be taken in TERAPOD, highlighting the specific challenges and aimed innovations that are targeted

Ultrasonic evidence of an uncorrelated cluster formation temperature in manganites with first-order magnetic transition at T_C

Ultrasonic attenuation and phase velocity measurements have been carried out in the ferromagnetic perovskites La_{2/3}Ca_{1/3}MnO_3 and La_{2/3}Sr_{1/3}MnO_3. Data show that the transition at the Curie temperature, T_C, changes from first- to second-order as Sr replaces Ca in the perovskite. The compound with first-order transition shows also another transition at a temperature T* > T_C. We interpret the temperature window T_C < T < T* as a region of coexistence of a phase separated regime of metallic and insulating regions, in the line of recent theoretical proposals.Comment: 4 pages, 2 figure

The role of ACTH in the pathogenesis of Polycystic Ovarian Syndrome in the rat: hormonal profiles and ovarian morphology.

Numerous hypotheses have been proposed about the pathogenia of the polycystic ovarian syndrome (PCOS). However, hormonal control of the persistent follicle has not been established. The objective of the present study was to compare the follicular structure and hormonal profiles of rats treated with adrenocorticotrophic hormone (ACTH) with two experimental models of PCOS. ACTH-treated animals were compared with those exposed to continuous light, treated with estradiol valerate, and control (in proestrous and diestrous). Serum hormone levels, histomorphometrical changes, and immunoexpression of vimentin, cytokeratins, cadherins, and proliferating cell nuclear antigen (PCNA) were examined. Treatment with ACTH resulted in an elevation of corticosterone secretion with LH reduction but without changes in ovarian morphology. Although stress (or ACTH) stimulation may be only one pathophysiological mechanism involved in follicular cyst pathogenia in other species, we do not find important evidence to suppose that this would happen in rats.Fil: Baravalle, Celina. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Departamento de Ciencias Morfológicas. Laboratorio de Biología Celular y Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Salvetti, Natalia Raquel. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Departamento de Ciencias Morfológicas. Laboratorio de Biología Celular y Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mira, G. A.. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias; ArgentinaFil: Lorente, J. A.. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias; ArgentinaFil: Ortega, Hugo Hector. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Departamento de Ciencias Morfológicas. Laboratorio de Biología Celular y Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Caracterización energética de la unión de 1,3,6- naftalén trisulfonato al factor de crecimiento para fibroblastos ácido humano: implicaciones para su uso como agente anti-angiogénico

The equilibrium interaction of anti-cancer agent 1,3,6-naphatalene trisulfonate with human acidic fi broblast growthfactor has been studied by calorimetry. The affi nity decreases with increasing ionic strength. At pH 7.0 and 0.15 MNaCl concentration, a binding constant of the protein with the ligand was estimated in the 102 – 103 M-1 range, anaffi nity two orders of magnitude lower than that of aFGF with heparin. The interaction is enthalpically driven, andthe entropy change is unfavorable. A small heat capacity change with an unusual positive value of 90 cal K-1mol-1 wasdetermined from the temperature dependence of the enthalpies. Changes in accessible apolar and polar surface areasin the interaction were calculated from the thermodynamic data obtained and parametric equations in the literature.The results were compared with those measured from NMR data. The study includes structural bioenergetic considerationsabout the possible use of 1,3,6-naphatalene trisulfonate as an anti-angiogenic agent itself, or as a lead for thedevelopment of anti-angiogenic drugs.Se ha estudiado, mediante calorimetría isotérmica de reacción, la interacción del agente anticancerígeno 1,3,6-naftaléntrisulfonato con el factor de crecimiento para fi broblastos ácido humano. La afi nidad decrece con el aumento de lafuerza iónica. A pH 7,0 y NaCl 0,15 M, la constante de unión de la proteína con el ligando se encuentra en el rango102 – 103 M-1, una afi nidad dos órdenes de magnitud menor que la del FGFa por heparina. El cambio de entalpíafavorece la interacción, siendo el cambio de entropía desfavorable. De la dependencia del cambio de entalpía con latemperatura se calculó un pequeño cambio en la capacidad calorífi ca del proceso, con un valor excepcionalmentepositivo de 90 cal K-1mol-1. A partir de los datos termodinámicos medidos y de ecuaciones paramétricas establecidasen la literatura, se calcularon cambios en la superfi cie accesible al disolvente, tanto polar como apolar, que acompañana la interacción. Los resultados se compararon con los medidos mediante resonancia magnética nuclear. Elestudio incluye consideraciones de bioenergética estructural sobre el posible uso de 1,3,6-naftalén trisulfonato comoagente antiangiogénico o como molécula líder para el desarrollo de fármacos anti-angiogénicos