932 research outputs found

    Analysis of the mass and deformation variation rates over time and their influence on long-term durability for specimens of porous material

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    In an environment subjected to continuous climatic evolution, the study of the long-term behavior of building materials subject to environmental aggressions becomes an extremely important factor in evaluating the sustainability of these materials over time. The damage due to the aggression of external agents does not only affect the surface of the building but can cause a loss of performance in the mechanical qualities of the material with the worsening of the safety conditions of the entire structure. The velocity of the damage evolution is an interesting item. Here the variation velocity of some parameters characterizing the porous materials subjected to aggressive actions is dealt with. Starting from standard material characterization tests, extending the test times, the rate of variation of the mass and the deformation induced by the absorption of saline solutions in the porous medium and the variation of these speeds over time were evaluated. Hypotheses are formulated on the influence that this speed on the degradation of the material in the short and long time. The results obtained show how long-term aggressive action can cause internal damage with a consequent critical increase in absorption, mass and deformation, phenomena that can induce even severe damage to structural element

    Seismic vulnerability assessment of historic centres with two fast methods based on Cartis survey methodology and fragility curves

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    After an earthquake, legislation tends to permit the rapid demolition of damaged buildings, including the built heritage, for safety reasons, as was the case for many small historic centers after the 2016 earthquake in central Italy. A balance should, of course, be struck between safety and preservation. There must be a willingness to engage in continuous interaction with the various bodies involved in post-earthquake management, particularly in the preventive phase of the complex activities regarding the issues of the seismic vulnerability of historic built. The widespread historical built heritage in Italy requires fast and reliable assessment procedures that allow a large-scale evaluation of the vulnerability of historical buildings before a seismic event. To this end, a proposal is presented here for the inverse use of the protocol for the seismic vulnerability survey of historic centers by means of a system called CARTIS form, coordinated since 2015 by the Italian consortium of Seismic and Structural Engineering Laboratories (ReLUIS). This rapid assessment is compared with an equally fast method for constructing fragility curves, based only on the information available in the ReLUIS–CARTIS database, defining the relationship between the probability of reaching a level of loss of structural safety or a vulnerability index as a function of the seismic acceleration PGA and the ground orography. The methodology outlined could be considered to be progress in cultural heritage diagnostics on a large scale, considering cultural heritage to be the diffuse historical residential masonry buildings that form the historic center

    About Superluminal motions and Special Relativity: A Discussion of some recent Experiments, and the solution of the Causal Paradoxes

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    Some experiments, performed at Berkeley, Cologne, Florence, Vienna, Orsay, Rennes, etc., led to the claim that something seems to travel with a group velocity larger than the speed c of light in vacuum. Various other experimental results seem to point in the same direction: For instance, localized wavelet- type solutions to Maxwell equations have been found, both theoretically and experimentally, that travel with superluminal speed. [Even muonic and electronic neutrinos [it has been proposed] might be "tachyons", since their square mass appears to be negative]. With regard to the first-mentioned experiments, it was recently claimed by Guenter Nimtz that those results with evanescent waves (or tunneling photons) imply superluminal signal and impulse transmission, and therefore violate Einstein causality. In this note we want to stress that, on the contrary, all such results do not place relativistic causality in jeopardy, even if they referred to actual tachyonic motions: In fact, Special Relativity can cope even with superluminal objects and waves. For instance, it is possible (at least in microphysics) to solve also the known causal paradoxes, devised for faster than light motion, although this is not widely recognized yet. Here we show, in detail and rigorously, how to solve the oldest causal paradox, originally proposed by Tolman, which is the kernel of many further tachyon paradoxes (like J.Bell's, F.A.E.Pirani's, J.D.Edmonds' and others'). The key to the solution is a careful application of tachyon mechanics, as it unambiguously follows from special relativity. At Last, in one of the two Appendices, we propose how to evaluate the group-velocity in the case of evanescent waves. [PACS nos.: 03.30.+p; 03.50.De; 41.20.Jb; 73.40.Gk; 84.40.Az; 42.82.Et ]Comment: LaTeX file: 26 pages, with 5 Figures (and two Appendices). The original version of this paper appeared in the Journal below

    bullous wells syndrome associated with non hodgkin s lymphocytic lymphoma

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    3/”l; eosinophils 14.3% neutrophils 48%, lymphocytes 31.2%, monocytes 6.5%, basophils 0.2%), total immunoglobulin E (IgE) = 751 IU/ml, C-reactive protein (CRP) 1.25 mg/dl, erythrocyte sedimentation rate (ESR) in the first hour 60 mm; viral markers (Epstein Barr virus, cytomegalovirus, hepatitis A, B and C virus), cryoglobulin, ANCA, LAC, ANA, ENA and anti-DNA antibodies were all negative. Histopathological examination of the lesion on the left leg showed an epidermis characterized by multiple, sometimes confluent vesicles containing serum and eosinophil granulocytes. The underlying papillary dermis was markedly oedematous, with focal and minimal erythrocytic extravasations and an interstitial eosinophil granulocytic infiltrate. The reticular dermis was infiltrated by a large number of prevalently perivascular lymphocytic elements and numerous perivascular and interstitial eosinophil granulocytes, which also extended along the interlobular hypodermal septa and, to a lesser extent, the hypodermic lobules. The reticular dermis also showed some small and isolated flame figures (Fig. 2). The diagnosis of Wells' syndrome was made on the basis of the clinical picture and the histological findings, together with a negative direct immunofluorescence test (5). Having excluded pharmacological, infective, vasculitic and inflammatory causes, the subsequent instrumental and laboratory investigations were aimed at identifying a possible relapse of the patient's previous neoplastic disease. Complete abdominal ultrasonography, chest radiography and colonoscopy were negative, as was a search for tumour markers. The physical examination findings of numerous swollen inguinal and axillary lymph nodes therefore drew our attention to a possible underlying lymphoproliferative disease, and a subsequent lymph node biopsy revealed a picture compatible with a diffuse, small-cell non-Hodgkin's B lymphoma/ B-cell CLL, which was confirmed by a bone marrow biopsy

    Introducing a rainfall compound distribution model based on weather patterns sub-sampling

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    This paper presents a probabilistic model for daily rainfall, using sub-sampling based on meteorological circulation. We classified eight typical but contrasted synoptic situations (weather patterns) for France and surrounding areas, using a "bottom-up" approach, i.e. from the shape of the rain field to the synoptic situations described by geopotential fields. These weather patterns (WP) provide a discriminating variable that is consistent with French climatology, and allows seasonal rainfall records to be split into more homogeneous sub-samples, in term of meteorological genesis. <br><br> First results show how the combination of seasonal and WP sub-sampling strongly influences the identification of the asymptotic behaviour of rainfall probabilistic models. Furthermore, with this level of stratification, an asymptotic exponential behaviour of each sub-sample appears as a reasonable hypothesis. This first part is illustrated with two daily rainfall records from SE of France. <br><br> The distribution of the multi-exponential weather patterns (MEWP) is then defined as the composition, for a given season, of all WP sub-sample marginal distributions, weighted by the relative frequency of occurrence of each WP. This model is finally compared to Exponential and Generalized Pareto distributions, showing good features in terms of robustness and accuracy. These final statistical results are computed from a wide dataset of 478 rainfall chronicles spread on the southern half of France. All these data cover the 1953–2005 period

    Evaluation of the weight loss of raw beef cuts vacuum-packaged with two different techniques

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    In the present study, 25 cuts of shank form adult cattle coming from the same slaughtering batch, were withdrawn just after manual sectioning/deboning, and each divided into two pieces (Prox and Dist) of approximately the same weight, that were vacuum packaged by using two different packaging systems: vacuum chamber machine with a bag material and a thermo-forming packaging machine with top and bottom webs named BAG and THF respectively. The packed cuts were stored at 2-3\ub0C for 20 days. The drip loss was calculated at the end of the storage as the difference between drained weight and net. Internal muscle pH and pH of the exudate present in the package and microbiological analyses (by pooling the samples) were performed at T0 and at the end of the storage. The drip loss, was significantly lower with BAG packaging: this difference was evident after 20 days of storage (average \ub1 STD BAG vs THF = 1.04\ub10.36% vs 1.71\ub10.42%; P<0.01). The values were, in general, low for both the packaging systems, never above 2%. Moreover, shrink bag packages are characterized by better overall pack appearance and less plastic weight per pack. Forming step reduce the thickness of ther-moforming material lowering the mechanical resistance and the barrier to oxygen, on the contrary after shrinking bag materials are thickened. The pH of muscles was stable, although a slight increase was evidenced after 20 (average \ub1 STD BAG vs THF= 5.73\ub10.05 vs 5.78\ub10.09; P<0.01), due to the ageing of meat. The pH of the exudate was equal at T20 (average \ub1 STD BAG vs THF = 5.34\ub10.20 vs 5.33\ub10.17). The drip loss didn\u2019t influence the development of all the microflora; in particular LAB, that represented the main microbial population, showed a gradual increase from T0 (2.20\ub10.41 Log CFU/g) to T20 (average \ub1 STD BAG vs THF= 4.76\ub10.29 Log CFU/g vs 4.75\ub10.0.15 Log CFU/g). No Enterobacteriaceae showed an increase, if compared to the initial counts, due to the prolonged storage and the gradual growth of ephemeral microorganisms, without differences among the two series (Enterobacteriaceae: T0=<1.7 Log CFU/g to T20 average \ub1 STD BAG vs THF = 2.83\ub10.77 Log CFU/g vs 3.09\ub10.0.70 Log CFU/g). In conclusion, the use of the BAG system demonstrated to have an effect in reducing the drip loss of beef cuts during the refrigerated storage, with only slight influence on the other characteristics of raw meat

    The stone roof of the tholos of Athena Pronaia in Delphi: structural hypotheses starting from fragments of marble tiles

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    This contribution is the first step of a multi-disciplinary research project, aimed at studying the roof of the tholos of Athena Pronaia in Delphi, dating back to the first decades of the 4th century BC. The starting point of this research is the fascination exerted by the tectonic quality of the temple, comprising some complex fragments of marble tiles belonging to the roof of the tholos. Despite the number of studies on this sanctuary, the poor state of preservation and lack of original material did not allow archaeologists to perform concluding research on its original configuration, in particular with reference to the reconstruction of the roof. Aware of the complexity of this topic, this contribution aims at exploring two possibilities, namely, on the one hand, that the fragments of tiles constitute elements supported by a wooden structure, and on the other hand, that they are structural elements of a stone system subjected to compressive stresses. Our contribution intends to serve as food for thought on the need for archaeological studies to be accompanied not only by advanced surveys in the field, aimed at the precise definition of the geometry of the finds, but also by architectural and structural investigations which make it possible to verify the feasibility of the hypothetical reconstructions of the architectural elements aware of the construction techniques used in the past

    The dual nature of trehalose in citrus canker disease: A virulence factor for Xanthomonas citri subsp. citri and a trigger for plant defence responses

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    Xanthomonas citri subsp. citri (Xcc) is a bacterial pathogen that causes citrus canker in susceptible Citrus spp. The Xcc genome contains genes encoding enzymes from three separate pathways of trehalose biosynthesis. Expression of genes encoding trehalose-6-phosphate synthase (otsA) and trehalose phosphatase (otsB) was highly induced during canker development, suggesting that the two-step pathway of trehalose biosynthesis via trehalose-6-phosphate has a function in pathogenesis. This pathway was eliminated from the bacterium by deletion of the otsA gene. The resulting XccΔotsA mutant produced less trehalose than the wild-type strain, was less resistant to salt and oxidative stresses, and was less able to colonize plant tissues. Gene expression and proteomic analyses of infected leaves showed that infection with XccΔotsA triggered only weak defence responses in the plant compared with infection with Xcc, and had less impact on the host plant's metabolism than the wild-type strain. These results suggested that trehalose of bacterial origin, synthesized via the otsA-otsB pathway, in Xcc, plays a role in modifying the host plant's metabolism to its own advantage but is also perceived by the plant as a sign of pathogen attack. Thus, trehalose biosynthesis has both positive and negative consequences for Xcc. On the one hand, it enables this bacterial pathogen to survive in the inhospitable environment of the leaf surface before infection and exploit the host plant's resources after infection, but on the other hand, it is a tell-tale sign of the pathogen's presence that triggers the plant to defend itself against infection.Fil: Piazza, AinelĂ©n Melanie. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Rosario. Instituto de BiologĂ­a Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂ­micas y FarmacĂ©uticas. Instituto de BiologĂ­a Molecular y Celular de Rosario; ArgentinaFil: Zimaro, Tamara. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Rosario. Instituto de BiologĂ­a Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂ­micas y FarmacĂ©uticas. Instituto de BiologĂ­a Molecular y Celular de Rosario; ArgentinaFil: Garavaglia, Betiana Soledad. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Rosario. Instituto de BiologĂ­a Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂ­micas y FarmacĂ©uticas. Instituto de BiologĂ­a Molecular y Celular de Rosario; ArgentinaFil: Ficarra, Florencia Andrea. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Rosario. Instituto de BiologĂ­a Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂ­micas y FarmacĂ©uticas. Instituto de BiologĂ­a Molecular y Celular de Rosario; ArgentinaFil: Thomas, Ludivine. King Abdullah University of Science and Technology; Arabia SauditaFil: Marondedze, Claudius. King Abdullah University of Science and Technology; Arabia SauditaFil: Feil, Regina. Max Planck Institute of Molecular Plant Physiology; AlemaniaFil: Lunn, John E.. Max Planck Institute of Molecular Plant Physiology; AlemaniaFil: Gehring, Chris. King Abdullah University of Science and Technology; Arabia SauditaFil: Ottado, Jorgelina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Rosario. Instituto de BiologĂ­a Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂ­micas y FarmacĂ©uticas. Instituto de BiologĂ­a Molecular y Celular de Rosario; ArgentinaFil: Gottig Schor, Natalia. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Rosario. Instituto de BiologĂ­a Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂ­micas y FarmacĂ©uticas. Instituto de BiologĂ­a Molecular y Celular de Rosario; Argentin
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