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Statistical Treatment (statistical + treatment)
Selected AbstractsClimatic factors influencing the isotope composition of Italian olive oils and geographic characterisationRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 3 2009Paola Iacumin The purpose of this study was to investigate the possibility of identifying oil source areas by means of simple measurements on the natural samples avoiding time-consuming sample treatments. The oxygen and carbon isotopic values of 150 samples of extra-virgin olive oil from eight different Italian regions and from three different years of production were measured according to well-established techniques. Statistical treatments of the results obtained show a very good correlation of the ,18O of oil with latitude, mean annual temperature, and mean relative humidity at the collection site. No correlation is found with elevation and mean annual precipitation. The shift of the oil ,18O per degree centigrade of the mean annual temperature is quantitatively close to that calculated for atmospheric precipitation in continental areas. Accordingly, in our measurements, the year of oil production can be identified on the basis of the ,18O value (mean 2004 temperatures were higher than 2005 temperatures). On the contrary, the oil ,13C values show no correlation with the above variables but only with latitude and, consequently, are less suitable for discriminating the geographic origin of oil. However, the ,13C values are suitable to indicate biological differentiation while the ,18O values are not. Copyright © 2009 John Wiley & Sons, Ltd. [source] An ab initio simulation of the UV/visible spectra of N -benzylideneaniline dyesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 15 2009Denis Jacquemin Abstract The structural parameters and the absorption spectra of more than thirty N -benzylideneaniline dyes have been determined with a theoretical scheme combining the time-dependent density functional theory and the polarizable continuum model. For the unsubstituted molecule, the PBE0 hybrid nicely reproduces both the measured structural parameters and the absorption spectrum, and we demonstrate that the nature of the two first transitions is reversed compared with azobenzene. For the set of substituted compounds, the average TD-DFT error (0.19 eV), that can be significantly reduced by a simple statistical treatment, mainly originates in the charge-transfer states of push,pull derivatives, whereas local transitions are accurately modeled. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Evaluation of the protonation thermochemistry obtained by the extended kinetic method,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2006Guy Bouchoux Abstract An evaluation of the results obtained by the extended kinetic method for a series of representative bases is presented here. Analysis of the original experimental data is conducted using the orthogonal distance regression (ODR) statistical treatment. A comparison with the proton affinities and protonation entropies obtained from variable temperature equilibrium constant measurements demonstrate deviations, which may be ascribed to random and systematic errors. Considerable random errors are associated with the extended kinetic method if the number of reference bases and the range of effective temperatures are too low. It is also confirmed that large systematic errors on proton affinities and protonation entropies are obtained when large protonation entropy is associated with the considered system. It is, however, encouraging to note that the gas phase basicities obtained by the extended kinetic method are generally comparable to that obtained by other methods within a few kJ/mol. Copyright © 2006 John Wiley & Sons, Ltd. [source] Model-based measurement of latent risk in time series with applicationsJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 1 2008Frits Bijleveld Summary., Risk is at the centre of many policy decisions in companies, governments and other institutions. The risk of road fatalities concerns local governments in planning countermeasures, the risk and severity of counterparty default concerns bank risk managers daily and the risk of infection has actuarial and epidemiological consequences. However, risk cannot be observed directly and it usually varies over time. We introduce a general multivariate time series model for the analysis of risk based on latent processes for the exposure to an event, the risk of that event occurring and the severity of the event. Linear state space methods can be used for the statistical treatment of the model. The new framework is illustrated for time series of insurance claims, credit card purchases and road safety. It is shown that the general methodology can be effectively used in the assessment of risk. [source] The Fortified Site of Leceia (Oeiras) in the Context of the Chalcolithic in Portuguese EstramaduraOXFORD JOURNAL OF ARCHAEOLOGY, Issue 1 2000JoÃo Luís Cardoso Research into the Chalcolithic period in the region of Lower Estremadura, south of Torres Vedras, western Portugal, has generated much new data from fortified sites and cemeteries. The lack, so far, of a thorough overview of this diverse body of information has hindered the definition of the Chalcolithic culture of the region. The economic, social and cultural transformation observed at sites with a long sequence beginning with the Late Neolithic, has never been analysed. The results obtained by the author in one of the most notable sites of the region, the fortified site of Leceia, near the town of Oeiras, are of particular interest. Seventeen excavation campaigns carried out since 1983 have provided a remarkable body of information. The characterization of other previously identified Chalcolithic groups in Portugal allow us to see how the Chalcolithic of Estremadura relates, at a regional level, with the cultural development to the north, the south, the hinterland and the coast. Of major importance to this discussion are the chronometric results obtained in Leceia. For the first time, the 36 radiocarbon dates and their subsequent statistical treatment have allowed us to establish absolute boundaries for the existing successive cultural phases of the Late Neolithic and the Early, Middle and Late Chalcolithic. [source] Mixing efficiency in a pin mixing section for single-screw extrudersPOLYMER ENGINEERING & SCIENCE, Issue 6 2001W. G. Yao Non-Newtonian, non-isothermal, 3D finite-element simulation of mixing performance in a pin mixing section with different axial gaps in the pins has been carried out according to their realistic configurations. The quantitative evaluation of mixing ability was based on the theory of kinematics of fluid mixing. To learn and to compare the local mixing performance in a standard screw and a pin mixing section, the local mixing efficiency distribution proposed by Ottino was calculated. Also, the RTDs of these mixers were calculated in an attemt to measure mixing. The integration of the two, namely, the integrating local mixing efficiency along a number of particle pathlines from entrance to exit, together with statistical treatment, which was referred as integral mixing efficiency, then gives a quantitative judgment of the total mixing ability of a continuous mixer. The calculated results showed a nonlinear dependence of the mixing ability of a pin mixing section on the axial gap of the pins. Finally, the calculation results were compared with the experimental ones obtained in our previous study. [source] The Provenance of Red Figure Vases From Locri Epizephiri (Southern Italy): New Evidence by Chemical AnalysisARCHAEOMETRY, Issue 2 2004P. Mirti Thirty-nine samples of red figure pottery found at Locri Epizephiri were analysed for 18 chemical elements by inductively coupled plasma emission spectroscopy. The finds, dated from the end of the sixth to the fourth century bc, were assigned to Attic, Sicilian and Locrian workshops due to their style of execution. Prior to facing the archaeological questions, possible biases on sample classification due to variable firing conditions, or to alteration during burial, were investigated: the results supported the opportunity of a refiring pre-treatment. Multivariate statistical treatment of the analytical data confirms the separation between Attic and non-Attic samples; comparison with the composition of black gloss pottery suggests that all the non-Attic red figure vases could be the output of Locrian workshops. [source] Reference values for clinical chemistry tests during normal pregnancyBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 7 2008A Larsson Objective, Reference values are usually defined based on blood samples from healthy men or nonpregnant women. This is not optimal as many biological markers changes during pregnancy and adequate reference values are of importance for correct clinical decisions. There are only few studies on the variations of laboratory tests during normal pregnancies, especially during the first two trimesters. It is thus a need to establish such reference values. Design, Longitudinal study of laboratory markers in normal pregnancies. Setting, Uppsala University Hospital, Sweden. Population, Healthy pregnant females. Methods, We have studied 25 frequently used laboratory tests during 52 normal pregnancies. Each woman was sampled up to nine times and the samples were divided according to collection time into the following groups: gestational week 7,17; week 17,24; week 24, 28; week 28,31; week 31,34; week 34,38; predelivery (0,2 weeks before delivery) and postpartum (>6 weeks after delivery). The 2.5 and 97.5 percentiles for these markers were calculated according to the recommendations of the International Federation of Clinical Chemistry on the statistical treatment of reference values. Results, Reference intervals are reported for plasma alanine aminotransferase, albumin, alkaline phosphatase, pancreas amylase, apolipoprotein A1, apolipoprotein B, aspartate aminotransferase, bilirubin, calcium, chloride, creatinine, cystatin C, ferritin, ,-glutamyltransferase, iron, lactate dehydrogenase, magnesium, phosphate, potassium, sodium, transferrin, triglycerides, thyroid-stimulating hormone, urate and urea during these pregnancy periods. Conclusions, Most of the analytes change during normal pregnancy. It is thus of importance to use special reference values during pregnancy. [source] | |||||||||||||