2,111 research outputs found

    Increasing data (INAA) on Ecuadorian obsidian artifacts: preliminary provenance and a clue for pre-Columbian eastward trade.

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    In this work we carried out INAA major (Na, K, Ca and Fe %) and trace (ppm) elements (plus Mn by FAAS analysis) of 15 obsidian samples (waste flakes) coming from an unknown archaeological site (14C-AMS age of 1425 AD) located on the south-eastern flank of the back-arc Sumaco volcano, in the Sub-Andean Ecuador (to the east of the Cordillera Real) and from two already known pre-Columbian archaeological localities: La Florida (Quito) and Milan (Cayambe). Literature compositional data of the Ecuadorian obsidian outcrops (Bigazzi et al., 1992, Asaro et al., 1994, Bellot-Gurlet et al., 1999, 2008) provide some constraints on the provenance of the analyzed waste flakes, even though different methods of analyses make comparisons a difficult task. Concerning the obsidian artifacts of La Florida and Milan, they come from the well known Sierra de Guamanì obsidian sources (Cordillera Real). By contrast, the obsidian fragments of the Sumaco settlement show Mn-rich, U- Th-poor compositions and relatively high Nb/Zr ratios, these characters being compatible with obsidian erratic pebbles recently discovered by Bellot-Gurlet et al. (2008) in some river banks of the Amazonian foothills draining the easternmost flanks of the Antisana volcano in the Cordillera Real as well. In this way, the obsidian artifacts found at the Sumaco site reinforce the opinion of Bellot-Gurlet et al. (2008) that Ecuadorian source inventory is not yet exhaustive. These preliminary inferences of provenance for the Sumaco obsidian findings would however need to be furtherly tested with the same analytical methods on both artifacts and sources. The Antisana volcano, located 30 km to WNW of the Amazonian foothills, seems to be the best candidate to find out additional primary outcrops of obsidian sources. Obsidian ancient trade was well established in Ecuador among the Andean people of the Cordillera Real and between them and people of the Pacific coast, whereas an eastward trade toward the rainforest people was never documented. In this framework, the archaeometric study of the obsidian samples of the 1425 AD site of Sumaco, located well eastward of the Cordillera Real, is of paramount importance in tracing the ancient routes of the obsidian trade toward the Amazonian region. It can not be also excluded that sub-Andean and Amazonian people direcly took advantage from obsidian secondary sources (i.e. within the river banks of the Amazonian foothills) rather than procurements from primary outcrops in the Cordillera Real

    Radiation Hardness tests with neutron flux on different Silicon photomultiplier devices

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    Radiation hardness is an important requirement for solid state readout devices operating in high radiation environments common in particle physics experiments. The MEGII experiment, at PSI, Switzerland, investigates the forbidden decay μ+→e+γ\mu^+ \to \mathrm{e}^+ \gamma. Exploiting the most intense muon beam of the world. A significant flux of non-thermal neutrons (kinetic energy Ek≥0.5 MeVE_k\geq 0.5 ~MeV) is present in the experimental hall produced along the beamline and in the hall itself. We present the effects of neutron fluxes comparable to the MEGII expected doses on several Silicon PhotoMulitpliers (SiPMs). The tested models are: AdvanSiD ASD-NUV3S-P50 (used in MEGII experiment), AdvanSiD ASD-NUV3S-P40, AdvanSiD ASD-RGB3S-P40, Hamamatsu and Excelitas C30742-33-050-X. The neutron source is the thermal Sub-critical Multiplication complex (SM1) moderated with water, located at the University of Pavia (Italy). We report the change of SiPMs most important electric parameters: dark current, dark pulse frequency, gain, direct bias resistance, as a function of the integrated neutron fluency.Comment: 9 pages, 6 figures. Proceedings from Instrumentation for colliding Beam Physics (INSTR-17) 27-02-2017/03-03-2017 Novosibirsk (R

    Parallel hardware architectures for the cryptographic Tate pairing

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    Identity-based cryptography uses pairing functions, which are sophisticated bilinear maps defined on elliptic curves. Computing pairings efficiently in software is presently a relevant research topic. Since such functions are very complex and slow in software, dedicated hard- ware (HW) implementations are worthy of being stud- ied, but presently only very preliminary research is avail- able. This work affords the problem of designing paral- lel dedicated HW architectures, i.e.,co-processors, for the Tate pairing, in the case of the Duursma-Lee algorithm in characteristic 3. Formal scheduling methodologies are applied to carry out an extensive exploration of the archi- tectural solution space, evaluating the obtained structures by means of different figures of merit such as computation time, circuit area and combinations thereof.Comparisons with the (few) existing proposals are carried out, show- ing that a large space exists for the efficient parallelHW computation of pairings

    Quality of Life in Glaucoma: A Review of the Literature

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    The ultimate goal of glaucoma management is the preservation of patients’ visual function and quality of life (QoL). The disease itself as well as the medical or surgical treatment can have an enormous impact on a patient’s QoL. Even the mere diagnosis of a chronic, irreversible, potentially blinding disorder can adversely affect the patient’s sense of well-being and QoL by eliciting significant anxiety. Patients with primary open-angle glaucoma rarely present with visual symptoms, at least early in the course of the disease. A better understanding of patient-reported QoL can improve patient–physician interaction and enhance treatment adherence by customizing treatment options based on individual patient profile, thus optimizing long-term prognosis. These aspects are summarized and critically appraised in this article

    Learning effect of humphrey matrix frequency doubling technology perimetry in patients with ocular hypertension

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    Aim: To evaluate the learning effect of Frequency Doubling Technology (FDT) perimetry using the Humphrey Matrix-FDT perimetry (Matrix) 24-2 full-threshold program on patients with 7 ocular hypertension experienced with standard automated perimetry. Methods: Twenty-four patients with Ocular hypertension underwent 5 full-threshold Matrix tests at intervals of 5 2 days. Learning effect was defined as an improvement at results for duration, perimetric indices, foveal sensitivity, Glaucoma Hemifield Test, and the number of points with a P < 5% and < 1% in the total and pattern deviation maps. Eccentricity, hemifield, and quadrant sensitivities were also addressed as Sources of differences in learning effect. Test-retest variability was also calculated for each repetition as the mean of the point-to-point interindividual standard deviations. Results: A learning effect was demonstrated for mean defect (P = 0.031, analysis of variance) and foveal sensitivity (P = 0.009) and it only affected the first test for both parameters. All the other parameters did not show any significant learning effect. The effect was independent From eccentricity and quadrant or hemifield sensitivities. Conclusions: The results of this study demonstrate that the learning effect for Matrix-FDT is mild and it may affect only the first test. Caution is needed in the analysis of the first Matrix-FDT examination and retest may be advisable in the presence of low mean defect

    Exploring the Heidelberg Retinal Tomograph 3 diagnostic accuracy across disc sizes and glaucoma stages: a multicenter study

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    To investigate and compare the diagnostic accuracy of the Heidelberg Retinal Tomograph 3 (HRT3) diagnostic algorithms and establish whether they are affected by optic disc size and glaucoma severity

    Effect of vacuum induced nucleation on the final product homogeneity

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    In the field of freeze drying of pharmaceutics the homogeneity of the sublimation flux during drying is fundamental to allow a final product with the same characteristics. Previous studies have shown that the control of freezing stage, in addition to a dramatic reduction of cycle duration, can also improve the homogeneity of the final batch. In this framework, this study is focused on the investigation of the effects of the Vacuum Induced Nucleation control method (modified in a previous work)[1,2] on the final structure of the product. Two aspects will be taken into consideration: the uniformity among vials of the same batch (inter-vial) and the uniformity of the structure along the height of the product (intra-vial). It has to be pointed out that a non-uniform product structure can have an impact on the protein aggregation and redistribution, and cause a partial cake collapse or micro-collapse. This investigation is really useful to define some limits of the control method used in this work

    Vacuum-Induced Surface Freezing for the Freeze-Drying of the Human Growth Hormone: How Does Nucleation Control Affect Protein Stability?

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    Abstract In the present work, the effect of controlled nucleation on the stability of human growth hormone (hGH) during freeze-drying has been investigated. More specifically, the vacuum-induced surface freezing technique has been compared to conventional freezing, both with and without an annealing step. Size exclusion chromatography and cell-based potency assays have been used to characterize the formation of soluble aggregates and the biological activity of hGH, respectively. The results obtained indicate that controlled nucleation has a positive effect on both cycle performance and product homogeneity because of the formation of bigger ice crystals, and characterized by a narrower dimensional distribution. From the point of view of hGH stability, we observed that vacuum-induced surface freezing is not detrimental to the biological activity of the protein, or aggregate formation. In addition, the effect of 2 different formulations, including trehalose or cellobiose, on protein preservation was also considered for this study
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