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This paper presents a novel automatic framework to perform 3D face recognition. The proposed method uses a Simulated Annealing-based approach (SA) for range image registration with the Surface Interpenetration Measure (SIM), as similarity measure, in order to match two face images. The authentication score is obtained by combining the SIM values corresponding to the matching of four different face regions: circular and elliptical areas around the nose, forehead, and the entire face region. Then, a modified SA approach is proposed taking advantage of invariant face regions to better handle facial expressions. Comprehensive experiments were performed on the FRGC v2 database, the largest available database of 3D face images composed of 4,007 images with different facial expressions. The experiments simulated both verification and identification systems and the results compared to those reported by state-of-the-art works. By using all of the images in the database, a verification rate of 96.5 percent was achieved at a False Acceptance Rate (FAR) of 0.1 percent. In the identification scenario, a rank-one accuracy of 98.4 percent was achieved. To the best of our knowledge, this is the highest rank-one score ever achieved for the FRGC v2 database when compared to results published in the literature.  相似文献   
2.
The C49C54 TiSi2 polymorphic transformation has been investigated trying to elucidate the relative role played by nucleation and growth in silicide formation. Samples having an amorphous layer and C54 seeds have been made by heat treatment of a Ti/Si bi-layer structure and subsequent suitable Ar ion implantation. In situ resistance measurements performed during heat treatments in controlled and purified atmosphere at constant heating rates and ex situ X-ray diffraction, MeV 4He+ backscattering spectrometry and cross-section transmission electron microscopy have been used to characterize the samples. The results show that in a sample with C49 the C54 nucleation occurs at 800°C; when C54 seeds are present the growth is appreciable already at temperatures as low as 400–500°C. It has also been shown that nucleation and growth of the C49 phase is a process competitive to the growth of the C54 phase.  相似文献   
3.
The extent of children's exposure to multiple toxic metals is not well described in many developing countries. We examined metal exposures in young children (6-37 months) from Montevideo, Uruguay and their mothers (15-47 years) participating in a community-based study. Hair samples collected from 180 children and their mothers were analyzed for: lead (Pb), cadmium (Cd), manganese (Mn), and arsenic (As) concentration using inductively coupled plasma-mass spectrometry (ICP-MS). Median metal levels (μg/g) were: Pb 13.69, Mn 1.45, Cd 0.17, and As 0.09 for children and Pb 4.27, Mn 1.42, Cd 0.08, and As 0.02 for mothers. Of the child and maternal samples, 1.7% and 2.9% were below the limit of detection (LOD) for Cd, and 21.3% and 38.5% were below the LOD for As, respectively. Correlations between maternal and child levels ranged 0.38-0.55 (p < 0.01). Maternal hair metal levels were the strongest predictors of metal concentrations in children's hair. Girls had significantly lower As levels than boys (p < 0.01) but did not differ on other metals. In addition, in bivariate logistic regressions predicting the likelihood that the child would be exposed to multiple metals, hemoglobin < 10.5 g/dL (OR = 2.12, p < 0.05), blood lead (OR = 1.17, p < 0.01), and the mother being exposed to two or more metals (OR = 3.34, p < 0.01) were identified as significant predictors of increased likelihood of multiple metal exposure. Older child age (OR = 0.96, p < 0.05), higher maternal education (OR = 0.35, p < 0.01), and higher number of household possessions (OR = 0.83, p < 0.01) were significantly associated with decreased likelihood of multiple metal exposure. Preschool children in Uruguay are exposed to multiple metals at levels that in other studies have been associated with cognitive and behavioral deficits. Sources of exposure, as well as cognitive and behavioral consequences of multiple metal exposure, should be investigated in this population.  相似文献   
4.
Lake Velenje is located in one of the most polluted regions in Slovenia, the Salek Valley. The major source of pollution in the valley is the coal-fired thermal power plant in Sostanj (STPP, capacity 775 MW). It has five separate units. All units have electrostatic precipitators for fly ash removal. Unit 4 also has installed a wet flue gas desulfurisation system (FGD system). Total mercury (THg) concentrations were measured in lignite, slag and ash samples from the STPP. In flue gas, different mercury species (THg, MeHg, Hg2+, Hg0) were determined separately for unit 4 and unit 5 which use different flue gas cleaning technology. Mercury and methyl mercury (MeHg) concentrations were also measured in lake water at different depths, in inflow water, outflow water, rain, snow and lake sediments in order to establish the influence of the power plant on the lake. Most mercury emitted from the power plant is in the elemental form. The ratio between oxidised and elemental Hg depends on the flue gas cleaning technology. Mass balance calculations have been performed for the STPP. The results show that the major sources of mercury in Lake Velenje are wet deposition and lake inflows. Total and MeHg concentrations in the water column are very low and can be compared to other non-contaminated freshwater lakes in the world.  相似文献   
5.
We previously showed that autocrine tumor necrosis factor (TNF) production in the TNF-sensitive L929sA fibrosarcoma cell line induced TNF resistance, which is correlated with downmodulation of both TNF receptors on the cell surface. We now analyzed whether autocrine TNF production also interfered with intracellular TNF signaling pathways. The L929sA-CAT-R55i cell line, in which cell death can be induced by controlled cytoplasmic expression of a trimeric fusion protein between chloramphenicol acetyltransferase and the intracellular domain of TNF-R55 (CAT-R55i), was supertransfected with the murine TNF gene. Expression of the latter conferred resistance to cell death induced by exogenous TNF, while cytotoxicity induced by CAT-R55i was not impaired. This demonstrates that autocrine TNF did not induce intracellular mechanisms that block TNF signaling leading to cell death. Thus the induction of TNF resistance via autocrine TNF production in L929sA cells is solely due to downmodulation of TNF receptors on the cell surface.  相似文献   
6.
The main goal of this work is to characterize the biochemical profile of three halophilous microalgal strains isolated from extreme ecosystems in northern Chile to assess their potential as possible sources of technological and commercial advantages. A procedure for the validation of a routine method for determining the total protein, carbohydrate, lipid and chlorophyll a (Chl-a) contents in Chlorella fusca, Dunaliella salina and Spirulina sp. has been developed. Detection limits of 10.8 μg/mg, 2.7 μg/mg and 5.6 μg/mg for total protein content and 3.5 μg/mg, 1.8 μg/mg and 8.8 μg/mg for total carbohydrate content were determined in C. fusca, D. salina and Spirulina sp., respectively. Most of the biological macromolecule levels measured in the microalgae were in accordance with the magnitude of previously reported data for other strains of the same taxa. However, lower levels than expected of lipids and Chl-a were measured in C. fusca and Spirulina sp., which may be associated with an imbalance between specific growth rates and the rate of macromolecule synthesis. The protein values measured in Spirulina sp. (52.3 ± 2.2 μg/mg DW) were close to the lower limit of the range reported in the literature for non-halophilous strains of the same genus. Except for the Chl-a quantification procedure, the analytical methods for macromolecules had a high degree of repeatability and reproducibility. The variability among repeated measurements of Chl-a was associated with auto-degradation processes during pigment extraction.  相似文献   
7.
Boron activation and carrier mobility were measured after low temperature furnace heat treatments, in silicon layers implanted with BF 2 + ions at 60 keV and at fluence in the 1 − 5 × 1015 ions cm−2 range. These quantities were correlated with boron and fluorine chemical depth profiles obtained with secondary ion mass spectrometry (SIMS), and with the lattice defects revealed by transmission electron microscopy (TEM). High dopant activation, well above the extrapolated boron solid solubility, was found for all the fluences investigated after a thermal treatment of 20 min at 600‡ C. In the high fluence implanted samples, the solid phase epitaxial regrowth of the amorphous layer induces a severe fluorine redistribution which causes the formation of a defective band at the sample surface containing microtwins and small precipitates; a decrease in both the activated dopant concentration and carrier mobility was found in this region. The comparison with dopant activation data obtained in samples diffused at higher temperature (from 900 to 1000‡ C) shows that twins are electrically active only when they are decorated by isolated impurities and/or in presence of very small precipitates.  相似文献   
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Various vegetables (broad beans, corn, potato, alfalfa and onion) were sampled in northern Chile, Antofagasta Region. They are the basis of human nutrition in this region and of great relevance to human health. This region is characterized by volcanic events (eruptions, thermal springs, etc.). Most of the vegetables cultivated in this area enter the local markets for a population of approximately 4000 people, whose ancestors were mainly atacame?os and quechuas (local indigenous people). The cadmium and lead in these foods was determined by differential pulse anodic stripping voltammetry (DPASV). Results indicate that the highest concentration of Pb and Cd are in the potato skin, while the edible part of the potatoes contained a lower concentration of these metals. The INAA analyses of As in the vegetables from Socaire and Talabre, two towns located close to active volcanoes (e.g. Lascar), show a very high As content: 1850 microg/kg in corn (Socaire) and 860 microg/kg in potatoes (+ skin) (Talabre). These values exceed the National Standard for arsenic (500 microg/kg) by approximately 400% and 180%, respectively. In general, the data show a concentration of Pb greater than Cd with the potential for some vegetables to accumulate heavy metals, The values, expressed in fresh weight, vary from 0.2 to 40 microg/g for Cd and from 0.6 to 94 microg/g for Pb. These concentration intervals, except that of arsenic, are within the recommended standards in the Food Sanitary Regulation (Decree 977), which, expressed as fresh weight, must be equal to or smaller than 500 microg/kg for Pb. There is no legal standard for Cd.  相似文献   
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