Search results for "Absolut"

Chemical constituents of the root wood of Erythrina sacleuxii and determination of the absolute configuration of suberectin

2020

Phytochemical investigation on the root wood of Erythrina sacleuxii (Leguminosae) led to the isolation of nine secondary metabolites (1-9). Compound 1 was isolated from the genus Erythrina for the first time. The pure compounds were identified on the basis of comprehensive spectroscopic and spectrometric analyses, while their absolute configurations were determined based on chiroptical measurements. Compounds 5 and 6 showed weak antifungal activity against Pyricularia oryzae with MIC values of 20 µg/mL.
  
 Bull. Chem. Soc. Ethiop. 2020, 34(1), 135-140.
 DOI: https://dx.doi.org/10.4314/bcse.v34i1.12

Screening and authentication of herbal formulations based on microextraction-assisted voltammetry of microparticles

2015

A simple solid state electrochemical methodology for screening and authentication of herbal formulations is described. The proposed method is based on the recording of the voltammetric response, in contact with aqueous buffers, of microparticulate films of antioxidant compounds resulting from micro-extraction of dried herbal samples with ethanol or acetone. The obtained voltammetric responses led us to differentiate between diverse active components upon application of bivariate and multivariate chemometric techniques. Resolution of herbal preparations containing two or more components is possible when well-separated voltammetric signals are recorded. In favorable cases, such characteristic…

Millennial-scale phase relationships between ice-core and Mediterranean marine records: insights from high-precision 40Ar/39Ar dating of the Green Tu…

2013

International audience; With the advent of annually-resolved polar ice records extending back to 70 ka, marine and continental paleoclimate studies have now matured into a discipline where high-quality age control is essential for putting on an equal pace layer-counted timescale models and Late Quaternary sedimentary records. High-resolution U-Th dating of speleothem records and 40Ar/39Ar dating of globally recorded geomagnetic excursions have recently improved the time calibration of Quaternary archives, reflecting the cross-disciplinary effort made to synchronize the geologic record at the millennial scale. Yet, tie-points with such an absolute age control remain scarce for paleoclimatic …

Illuminating Intcal During the Younger Dryas

2020

As the worldwide standard for radiocarbon (14C) dating over the past ca. 50,000 years, the International Calibration Curve (IntCal) is continuously improving towards higher resolution and replication. Tree-ring-based 14C measurements provide absolute dating throughout most of the Holocene, although high-precision data are limited for the Younger Dryas interval and farther back in time. Here, we describe the dendrochronological characteristics of 1448 new 14C dates, between ~11,950 and 13,160 cal BP, from 13 pines that were growing in Switzerland. Significantly enhancing the ongoing IntCal update (IntCal20), this Late Glacial (LG) compilation contains more annually precise 14C dates than any…

Mapping child maltreatment risk: a 12-year spatio-temporal analysis of neighborhood influences.

2017

Abstract Background ‘Place’ matters in understanding prevalence variations and inequalities in child maltreatment risk. However, most studies examining ecological variations in child maltreatment risk fail to take into account the implications of the spatial and temporal dimensions of neighborhoods. In this study, we conduct a high-resolution small-area study to analyze the influence of neighborhood characteristics on the spatio-temporal epidemiology of child maltreatment risk. Methods We conducted a 12-year (2004–2015) small-area Bayesian spatio-temporal epidemiological study with all families with child maltreatment protection measures in the city of Valencia, Spain. As neighborhood units…

Studies of the bromine spectrum and determination of transition probabilities for Br I and Br II lines

1999

In a wall-stabilized cascade arc at atmospheric pressure in mixtures of argon and bromine vapors thermal plasmas were generated. Arc currents between 25 and 60 A were used. Applying a spectrometer of medium dispersion, equipped with an optical multichannel analyzer (CCD detector), the spectra of neutral and singly ionized bromine in the range between 3300 and 10400 A were recorded. Line intensity measurements, corrected for self-absorption, at different operating conditions of the arc, were performed. A complete set of Br I transitions (5 lines) originating from a common upper level (branching fractions) was measured. In the case of the Br II spectrum intensities of 14 lines were determined…

Clamor de la justicia, contra los agravios de la Atalaya del 24 de marzo de 1815 / [por Fr. Josef del Salvador, Carmelita Descalzo

1815

Sociedades fragiles

2001

Bayesian dynamic modeling of time series of dengue disease case counts

2017

The aim of this study is to model the association between weekly time series of dengue case counts and meteorological variables, in a high-incidence city of Colombia, applying Bayesian hierarchical dynamic generalized linear models over the period January 2008 to August 2015. Additionally, we evaluate the model’s short-term performance for predicting dengue cases. The methodology shows dynamic Poisson log link models including constant or time-varying coefficients for the meteorological variables. Calendar effects were modeled using constant or first- or second-order random walk time-varying coefficients. The meteorological variables were modeled using constant coefficients and first-order …

Autocorrelation Metrics to Estimate Soil Moisture Persistence From Satellite Time Series: Application to Semiarid Regions

2021

Satellite-derived soil moisture (SM) products have become an important information source for the study of land surface processes in hydrology and land monitoring. Characterizing and estimating soil memory and persistence from satellite observations is of paramount relevance, and has deep implications in ecology, water management, and climate modeling. In this work, we address the problem of SM persistence estimation from microwave sensors using several autocorrelation metrics that, unlike traditional approaches, build on accurate estimates of the autocorrelation function from nonuniformly sampled time series. We show how the choice of the autocorrelation estimator can have a dramatic impac…