132 research outputs found

    Comparison between three glass fiber post cementation techniques

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    The aim of this experimental study was to compare the traditional cement systems with those of the latest generation, to assess if indeed these could represent of viable substitutes in the cementation of indirect restorations, and in the specific case of endodontic posts

    Valmadrera (LC), località Corno di Birone, Cornello Alto. Rilievo di strutture insediative. Relazione preliminare

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    L’insediamento altomedievale del Corno di Birone, loc. Cornello Alto (Valmadrera – LC), è stato individuato durante attività di ricognizione, nell’ambito del progetto “Geografia della difesa”, avviato da tempo dalla Cattedra di Topografia Antica dell’Università di Milano. La ripulitura e il rilievo delle strutture superstiti ha evidenziato quattro ambienti su un terrazzo a 600 m di quota, due dei quali parzialmente scavati nella roccia, e alcune opere di terrazzamento per la regolarizzazione della geomorfologia naturale. In assenza di scavi, la datazione del sito ad età altomedievale si propone sulla base dello stretto rapporto con il vicino sito di Monte Barro, e per la probabile funzione di controllo viario del sito stesso.Early medieval settlement in Corno di Birone, Cornello Alto (Valmadrera – LC), has been found in survey activities, in Ancient Topography Project “Geografia della Difesa” of the University of Milan.Cleaning and reliefing survivor structures, have been evidenced four rooms on a natural terrace to 600 m slm, two of which partially dug in the cliff, and some terrace-works for regularization of natural geomorphology. In absence of archaeological diggings, the dating of the site to early medieval age it’s proposed on the strait relationship with close site of Monte Barro, and looking to its probable function of road control

    Scanning electron microscopic analysis of the efficacy of acid etching on cat enamel

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    The effect of etching on cat enamel made with 40% orthophosphoric acid for different times was evaluated. Twenty-one cat teeth were selected and randomly divided into three groups of seven teeth each. They were subjected to etching on a circular area of the coronal enamel (diameter = 2 mm) for 30 s (group A), 45 s (group B) and 60 s (group C). The samples obtained were observed by a scanning electron microscope focusing on the border area between etched and unetched enamel, to highlight the differences. The micrographs were subjected to blind assessment of three experienced operators. The groups were statistically assessed with the Wilcoxon test. At 30, 45 and 60 s, the acid attack results only in the formation of an irregular enamel surface and without uncovering and attack of the prismatic organisation. Prismatic areas with preferential interprismatic action could be detected in few samples etched for 60 s. Analysis with ImageJ was also used to quantify the efficacy of acid etching in the conditions used for human enamel, by an evaluation of grey levels. In cat enamel the etching times considered are not as effective as in human enamel for the purpose of adhesion and the presence of a thick prismless layer could explain this result

    Intensity and phase retrieval of IR laser pulse by THz-based measurement and THz waveform modulation

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    Abstract THz radiation is of great interest for a variety of applications. Simultaneously with the demonstration of high-intensity THz sources the idea to use this radiation for particle acceleration started to be investigated. THz accelerating gradients up to GV/m have been demonstrated in laboratory. THz radiation can be generated through the optical rectification process induced in non-linear crystals by a pump laser. The temporal shape of the pump laser and in general its characteristics are important aspects to be known in order to produce THz radiation via optical rectification in a controlled way. Here we present a technique that can be used to retrieve the temporal profile characteristics (envelope and phase) of the pump laser, starting from the detection of the THz waveform/spectrum and the knowledge of the physical/optical properties of the crystal used to produce it. This work also shows that the THz field can be shaped by properly acting on the pump laser phase. The possibility to opportunely shape the THz field is of great importance for many applications. Therefore this work paves the way to the possibility to coherently and dynamically control the THz field shape

    The dynamic association between Frailty, CD4 and CD4/CD8 ratio in people aging with HIV

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    To investigate the association between current CD4+ T-cell count and CD4/CD8+ ratio with severity of frailty among people aging with HIV

    Extraordinary blowing snow transport events in East Antarctica

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    In the convergence slope/coastal areas of Antarctica, a large fraction of snow is continuously eroded and exported by wind to the atmosphere and into the ocean. Snow transport observations from instruments and satellite images were acquired at the wind convergence zone of Terra Nova Bay (East Antarctica) throughout 2006 and 2007. Snow transport features are well-distinguished in satellite images and can extend vertically up to 200 m as first-order quantitatively estimated by driftometer sensor FlowCapt™. Maximum snow transportation occurs in the fall and winter seasons. Snow transportation (drift/blowing) was recorded for ~80% of the time, and 20% of time recorded, the flux is >10-2 kg m-2 s-1 with particle density increasing with height. Cumulative snow transportation is ~4 orders of magnitude higher than snow precipitation at the site. An increase in wind speed and transportation (~30%) was observed in 2007, which is in agreement with a reduction in observed snow accumulation. Extensive presence of ablation surface (blue ice and wind crust) upwind and downwind of the measurement site suggest that the combine processes of blowing snow sublimation and snow transport remove up to 50% of the precipitation in the coastal and slope convergence area. These phenomena represent a major negative effect on the snow accumulation, and they are not sufficiently taken into account in studies of surface mass balance. The observed wind-driven ablation explains the inconsistency between atmospheric model precipitation and measured snow accumulation value. © 2009 The Author(s)

    Aging with HIV vs. HIV Seroconversion at Older Age: A Diverse Population with Distinct Comorbidity Profiles

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    People aging with HIV might have different health conditions compared with people who seroconverted at older ages. The study objective was to assess the prevalence of, and risk factors for, individual co-morbidities and multimorbidity (MM) between HIV-positive patients with a longer duration of HIV infection, and patients who seroconverted at an older age. We compared estimates across both groups to a matched community-based cohort sampled from the general population

    A frailty index predicts post-liver transplant morbidity and mortality in HIV-positive patients

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    Background: We hypothesized that frailty acts as a measure of health outcomes in the context of LT. The aim of this study was to explore frailty index across LT, as a measure of morbidity and mortality. This was a retrospective observational study including all consecutive 47 HIV+patients who received LT in Modena, Italy from 2003 to June 2015. Methods: frailty index (FI) was constructed from 30 health variables. It was used both as a continuous score and as a categorical variable, defining 'most frail' a FI > 0.45. FI change across transplant (deltaFI, \uce\u94FI) was calculated as the difference between year 1 FI (FI-Y1) and pre-transplant FI (FI-t0). The outcomes measures were mortality and "otpimal LT" (defined as being alive without multi-morbidity). Results: Median value of FI-t0 was 0.48 (IQR 0.42-0.52), FI-Y1 was 0.31 (IQR 0.26-0.41). At year five mortality rate was 45%, "optimal transplant" rate at year 1 was 38%. All the patients who died in the post-LT were most frail in the pre-LT. \uce\u94FI was a predictor of mortality after correction for age and MELD (HR = 1.10, p = 0.006) and was inversely associated with optimal transplant after correction for age (HR = 1.04, p = 0.01). Conclusions: We validated FI as a valuable health measure in HIV transplant. In particular, we found a relevant correlation between FI strata at baseline and mortality and a statistically significant correlation between, \uce\u94FI and survival rate

    Point-of-care hemostasis in children with congenital heart disease, the POCHEMO study : baseline reference values of thromboelastometry and impedance aggregometry

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    : Viscoelastic tests and impedance aggregometry allow coagulation evaluation at the bedside, but reference values are scarce in pediatrics. The aim of this study was to establish reference values of thromboelastometry and impedance aggregometry for this population and compare it between age groups. This prospective, single-center, observational study evaluates viscoelastic tests and impedance aggregometry in children with congenital heart disease. A total of 204 children were included with a median age of 3.6 years old. We provide references values for this population with median, percentile 2.5 and percentile 97.5. Infants demonstrate for extrinsic activity a shorter coagulation time (52 [49-55] vs. 56 [51-62] s, P = 0.007) and clot formation time (90 [71-118] vs. 113 [93-146] s, P < 0.0001) so as for intrinsic activity a shorter clot formation time (53 [44-69] vs. 75 [59-92] s, P < 0.0001). The maximal clot firmness was significantly stronger in infants for extrinsic (65 [61-69] vs. 59 [54-63] mm, P < 0.0001), intrinsic (68 [64-70] vs. 61 [57-65] mm, P < 0.0001), and fibrinogen (12 [9-16] vs. 10 [8-13] mm, P = 0.02) activities. Platelet aggregation was significantly higher in infants with an amplitude at 6 min of 28 [23-34] vs. 22 [15-27] Ω, P less than 0.0001, a maximum speed of 11 [9-13] vs. 7 [5-10] Ω/min, P less than 0.0001, and an area under the curve of 120 [92-135] vs. 86 [59-112] Ω min, P less than 0.0001. We provided the first reference values for impedance aggregometry and thromboelastometry in children with congenital heart disease. We showed that these infants tend to have accelerated coagulation and stronger clot firmness compared with older children, but this finding may have only minimal relevance when treating a bleeding child. Trial registration number: ClinicalTrials.gov (clinicaltrials.gov/ct2/show/NCT02387944)
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