103,085 research outputs found
Simulating the tail of the interference in a Poisson network model
No full textInterference among simultaneous transmissions represents the main limitation factor for the capacity and connectivity of dense wireless networks. In this paper we provide efficient simulation laws for the tail of the interference in a simple wireless ad hoc network model. Particularly, we consider node locations distributed according to a Poisson point process and various classes of light-tailed fading distribution
Demographic and household composition of refugee and internally-displaced Ukraine populations: findings from an online survey
No full textAuthored by Brienna Perelli-Harris, Orsola Torrisi, Michael G Head and Ken Brackstone, this Migration Research Series paper highlights the household composition and characteristics of those displaced by the Russian Federation's invasion of Ukraine. The paper showcases the findings of a rapid online health needs survey disseminated via Facebook between April and July 2022. The survey discusses the findings from 10,180 respondents, making suggestions for policies that can mitigate some of the effects of the displacement crisis
Redistribution of microtubules and Golgi apparatus in herpes simplex virus-infected cells and their role in viral exocytosis
No full textEarlier studies have shown that the Golgi apparatus was fragmented and dispersed in herpes simplex virus 1-infected Vero and HEp-2 cells but not in human 143TK- cells, that the fragmentation and dispersal required viral functions expressed concurrently with or after the onset of DNA synthesis (G. Campadelli-Fiume, R. Brandimarti. C. Di Lazzaro, P. L. Ward, B. Roizman, and M. R. Torrisi, Proc. Natl. Acad. Sci. USA 90:27982802, 1993), and that in 143TK- cells, but not Vero or HEp-2 cells, infected with viral mutants lacking the U(L)(20) gene virions were glycosylated and transported to extracellular space (J. D. Baines, P. L. Ward, G. Campadelli-Fiume, and B. Roizman, J. Virol. 65:6414-6424, 1991; E. Avitabile, P. L. Ward, C. Di Lazzaro, M. R. Torrisi, B. Roizman, and G. Campadelli-Fiume, J. Virol. 68:7397-7405, 1994). Experiments designed to elucidate the role of the microtubules and of intact or fragmented Golgi apparatus in the exocytosis of virions showed the following. (i) In all cell lines tested (Vero, 143TK-, BHK, and Hep-2) microtubules underwent fragmentation particularly evident at the cell periphery and then reorganized into bundles which circumvent the nucleus. This event was not affected by inhibitors of viral DNA synthesis. We conclude that redistribution of microtubules may be required but is not sufficient for the fragmentation and dispersal of the Golgi apparatus. (ii) In all infected cell lines tested, nocodazole caused fragmentation and dispersal of the Golgi and a far more extensive depolymerization of the microtubules than was seen in untreated, infected Vero or HEp-2 cells. Taxol precluded the depolymerization of the microtubules and fragmentation of the Golgi in both infected cell lines. Neither nocodazole nor taxol affected the exocytosis of infectious virus from Vero, HEp-2, or 143TK- cells infected with wild-type virus. We conclude that the effects of nocodazole or of taxol are dominant over the effects of vital infection in the cell lines tested and that viral exocytosis is independent of the organization of microtubules or of the integrity of the Golgi apparatus. Lastly, the data suggest that herpes simplex viruses have evolved an exocytic pathway for which the U(L)20 protein is a component required in some cells but not others and in which this protein dues nut merely compensate for the fragmentation and dispersal of the Golgi apparatus
Bionanocomposites based on a covalent network of chitosan and edge functionalized graphene layers
No full textIn this study, carbon papers and aerogels were prepared from chitosan and graphene layers with aldehydic edge functional groups (G-CHO) able to form chemical bonds with chitosan and thus to form a crosslinked network. A high surface area graphite was edge functionalized with hydroxyl groups (G-OH) through the reaction with KOH. G-CHO, with 4.5 mmol/g of functional group, was prepared from G-OH by means of the Reimer-Tieman reaction. Characterization of the graphitic materials was performed with elemental analysis, titration, X-ray analysis, Raman spectroscopy and by estimating their Hansen solubility parameters. CS and G-CHO were mixed with mortar and pestle and carbon papers and aerogels were obtained from a stable acidic water suspension through casting and liophilization, respectively. Free standing and foldable carbon papers and monolithic aerogels based on a continuous covalent network between G-CHO and CS were prepared. G-CHO, which had about 22 stacked layers, was extensively exfoliated in the carbon paper, as confirmed by the absence of the 002 reflection of the graphitic crystallites in the XRD pattern. Carbon paper was found to be resistant to solvents and to be stable for pH ⩾ 7. Composites revealed electrical conductivity. The covalent network between the graphene layers and CS, suggested by the IR findings, accounts for these results. This work demonstrates the effectiveness of a continuous covalent network between chitosan and graphene layers edge functionalized with tailor made functional groups for the preparation of carbon papers and aerogels and paves the way for the scale up of such a type of composites
Lundberg parameters for non standard risk processes
No full textWe consider risk processes with delayed claims in a Markovian environment, and
we study the asymptotic behaviour of
finite and infinite horizon ruin probabilities under the small claim
assumption. We also consider multivariate risk processes of the same kind, and we
give upper and lower bounds for the
Lundberg parameters of the corresponding total reserve. Our results have strong
analogies with those one in the paper by Juri (Super modular order and Lundberg exponents, 2002)
Laser and electron beams physical analyses applied to the comparison between two silver tetradrachm greek coins
No full textPhysical analyses by Laser Ablation coupled to Mass Quadrupole Spectrometry (LAMQS), and Energy Dispersive X-ray fluorescence (EDX) induced by electron beam are applied to the investigation of two silver Tetradrachm Greek coins. Quantitative analysis of elements, silver compounds and isotopic ratios have been investigated in the two samples. Significant differences in the elemental content and in the morphological aspects are observed
Asymptotic results for perturbed risk processes with delayed claims
No full textThe object of this paper is the study of some asymptotic properties of the perturbed risk process with delayed claims, which is the sum of a Brownian motion with drift and a shot-noise whose underlying point process is a doubly stochastic Poisson process. More in particular, under suitable hypotheses, we show that it satisfies a large deviation principle, and we give
asymptotic estimates of the corresponding ruin probabilities. Moreover, we introduce two suitable processes which can be seen as simplified versions of the original process, and we show some inequalities between the rate function and the Lundberg
parameter concerning the original process, and the rate functions and the Lundberg parameters concerning the simplified versions, respectively
Graphene-based materials: properties, advancements and applications
No full textGraphene-based materials have peculiar optical, electrical, mechanical and chemical properties, which make them useful for making thin films and thick sheets suitable for different needs. Matter physics, nuclear physics, microelectronics, biomedicine, engineering, agriculture and cultural heritage just represent some of the sectors in which these materials can be successfully used. The advancements allow us to go from a given graphene-based material to another transforming, for example, the insulator graphene oxide to electrically and thermally conductive reduced graphene oxide. Thanks to the interesting properties possessed by graphene-based materials, it is possible to realize gas sensors, dosimeters for ionizing radiation, light detectors, electronic devices, membranes for gases and desalination, biocompatible surfaces, medical protheses and thin coating films to preserve underlying layers. Different analysis techniques are presented to control the physical modifications of reduced graphene oxide (rGO) due to the different treatments for the pristine one. The paper reports the possibility to realize GO micro-dosimeters for ionizing radiations, sensors for air humidity and other gases, field effect transistors as the detector of visible and UV radiations, GO and rGO membranes realization for different gases, source ion strippers to enhance the charge state of different ions to be accelerated. Some of these aspects and possible applications will be presented and discussed with measurements carried out in our laboratories
Role of lipids and phenolic compounds in the anaerobic treatment of olive oil mill effluents
No full textThe inhibitory effects of olive oil mill effluents (OME) on methanogenesis were studied by using p-hydroxybenzoic acid (HBA) and oleic acid (OA) as model compounds for phenolic compounds and Lipids respectively. The addition of HBA (0.3 g 1(-1)') to diluted OME (5.7 g COD 1(-1)) had a negligible effect on methanogenesis in terms of kinetics and final methane yield. Strong inhibition was observed only at high HBA concentrations (6 g 1(-1)). The OA inhibited methane production much more strongly Indeed, 0.35 g 1(-1) of OA were able to double the lag phase for methanogenesis fi om diluted OME. With both compounds, the presence of an easily biodegradable co-substrate (glucose) did not increase the rate of substrate degradation nor methane formation. OME acidogenesis was significantly less sensitive than methanogenesis to the inhibitory effects exerted by OA and HBA, even at relatively high concentrations of the model compounds
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