360 research outputs found
A Look at Women and Abortion in the United States
The issue of abortion is defined by ethical questions and, often, controversial views. This paper argues the importance of a coherent and enhanced effort to study the quantitative relationship between women’s characteristics and the average number of abortions in the United States. It specifically looks at the average number of previous abortions and socioeconomic and demographic characteristics, as this relationship has not been explored before in the existing literature. We expect to establish a correlation between the average number of previous abortions and characteristics such as age, marital status, income and highest degree of education completed. An empirical model is developed, and then studied using regression analysis. Even though this study has limitations stemming from the nature of the data and the methodology employed, it illustrates that variables such as age, marital status, religion and education, employment status, income, and metropolitan status do influence the number of previous abortions a woman has had. The broader implications of this study suggest that the issue of abortion should be addressed with a clear focus on the most interested party, namely, women
Utilization of Olive Mill Waste in Microbial Electrolysis Cell
Olive oil production is a source of huge amount of residuals knowns as OMW (Olive Mill Waste). The sustainable management and treatment of this waste is challenging due to presence of high amount of specific pollutants. The OMW is characterized by very high COD to BOD ratio with considerable content of polyphenols reaching up to 15g/l. Due to this, the biological utilization of OMW could be hindered or very slow when the conventional aerobic and anaerobic methods are used.In this study, the Microbial Electrolysis Cell (MEC) technology was applied as an alternative treatment approach. The method offers COD reduction and energy recovering in the form of hydrogen. The results demonstrated up to 65% efficiency in terms of COD and polyphenols removal which suggest that MEC, could be considered as an initial treatment stage in OMW utilization
Recent developments in the rapid analysis of plants and tracking their bioactive constituents
Natural products chemistry has witnessed many new developments in the last 5 years like extractions with subcritical water and ionic liquids, LC/HRMS and LC/SPE/cryo-NMR, UHPLC, TLC/MS, MS-based preparative HPLC, comprehensive chromatography (GC × GC, LC × LC), high-throughput screening, introduction of monolithic columns, miniaturisation, and automated structure identification. Nevertheless identifying bioactive constituents in complex plant extracts remains a tedious process. The classical approach of bioassay guided fractionation is time-consuming while off-line screening of extracts does not provide information on individual compounds and sometimes suffers from false positives or negatives. One way out of this is by coupling chromatography with chemical or biochemical assays, so called high resolution screening. An example is the development of HPLC on-line assays for antioxidants. By the post-column addition of a relatively stable coloured radical like DPPH¿ or ABTS¿+, radical scavengers are detected as negative peaks because in a reaction coil they reduce the model radical to its reduced, non-coloured form. When combined with LC/DAD/MS and LC/SPE/NMR, reliable identification of active constituents becomes possible without the necessity of ever isolating them in a classical sense. Also for finding leads for new drugs, combining HPLC with biochemical assays is interesting but technically more difficult. Most enzymes do not work at the organic modifier concentrations commonly encountered in RP-HPLC and the reaction time is often longer requiring dilution and lengthy coils respectively. Therefore, new techniques have to be implemented to gain the required sensitivity for on-line enzyme assays. For stable analytes, high temperature LC offers a solution to the organic modifier problem. When enzymes are highly expensive, like those used in the screening for Cytochrome P450 inhibitors, miniaturisation to chip format may offer a way out. Microreactors (chips) are not only useful for miniaturising larger assays but also offer completely new prospects in phytochemical analysis. One such application is in the sample clean-up of acids and bases like alkaloids. In a lay-out of three parallel channels of 100 ¿m width with the middle one containing organic phase and the two outer ones water of high pH (feed phase) and low pH (trapping phase) such a chip replaces two classical LLE steps but is much faster and requires less solvents and less manpower input
Solid Liquid Extraction of Phenolic and Flavonoid Compounds from Cotinus coggygria and Concentration by Nanofiltration
Extraction kinetics of polyphenols and flavonoids from plant material and their separation and concentration by nanofiltration were investigated. The kinetics experiments were carried out with Cotinus coggygria. The influence of the extraction solvent on the extraction rate was defined. Four different extraction solvents or mixtures were applied – methanol, azeotropic ethanol, 50/50 ethanol/water mixture, and pure water. The optimum extraction rate of flavonoids and polyphenols was achieved by using 50 % ethanol as a solvent for extraction. This solvent mixture was used for generating extracts for the nanofiltration experiments. Organic solvent nanofiltration membranes from DuraMemTM series with different pore sizes (200, 300 500 and 900 Da) were tested in dead-end and cross-flow filtration systems. Flux and rejection data were obtained for every membrane type. Very good separation and respectively concentration of the extracted useful compounds was achieved (rejection for polyphenols and flavonoids is 91 and 93 %, respectively). During a feed/extract concentration experiment, the constant polyphenols and flavonoids rejection was measured. The results suggest that the nanofiltration technology could be combined successfully with solid-liquid extraction for natural sourced valuable compounds enrichment
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses IX. Time delays, lens dynamics and baryonic fraction in HE 0435-1223
We present accurate time delays for the quadruply imaged quasar HE 0435-1223.
The delays were measured from 575 independent photometric points obtained in
the R-band between January 2004 and March 2010. With seven years of data, we
clearly show that quasar image A is affected by strong microlensing variations
and that the time delays are best expressed relative to quasar image B. We
measured Delta_t(BC) = 7.8+/-0.8 days, Delta_t(BD) = -6.5+/-0.7 days and
Delta_t_CD = -14.3+/-0.8 days. We spacially deconvolved HST NICMOS2 F160W
images to derive accurate astrometry of the quasar images and to infer the
light profile of the lensing galaxy. We combined these images with a stellar
population fitting of a deep VLT spectrum of the lensing galaxy to estimate the
baryonic fraction, , in the Einstein radius. We measured f_b =
0.65+0.13-0.10 if the lensing galaxy has a Salpeter IMF and f_b =
0.45+0.04-0.07 if it has a Kroupa IMF. The spectrum also allowed us to estimate
the velocity dispersion of the lensing galaxy, sigma_ap = 222+/-34 km/s. We
used f_b and sigma_ap to constrain an analytical model of the lensing galaxy
composed of an Hernquist plus generalized NFW profile. We solve the Jeans
equations numerically for the model and explored the parameter space under the
additional requirement that the model must predict the correct astrometry for
the quasar images. Given the current error bars on f_b and sigma_ap, we did not
constrain H0 yet with high accuracy, i.e., we found a broad range of models
with chi^2 < 1. However, narrowing this range is possible, provided a better
velocity dispersion measurement becomes available. In addition, increasing the
depth of the current HST imaging data of HE 0435-1223 will allow us to combine
our constraints with lens reconstruction techniques that make use of the full
Einstein ring that is visible in this object.Comment: 12 pages, 10 figures, final version accepted for publication by A&
The impact of microcavity wire width on polariton soliton existence and multistability
We have developed a model of the nonlinear polariton dynamics in realistic 3D
non-planar microcavity wires in the driven-dissipative regime. We find that the
typical microcavity optical bistability evolves into multistability upon
variation of the model parameters. The origin of the multistability is
discussed in detail. We apply linear perturbation analysis to modulational
instabilities, and identify conditions for localisation of composite multi-mode
polariton solitons in the triggered parametric oscillator regime. Further, we
demonstrate stable polariton soliton propagation in tilted and tapered
waveguides, and determine maximum tilt angles for which solitons still exist.
Additionally, we study soliton amplitude and velocity dependence on the wire
width, with a view to engineering quantum photonic devices.Comment: 20 pages, 16 figure
Functional and structural leaf plasticity determine photosynthetic performances during drought stress and recovery in two platanus orientalis populations from contrasting habitats.
In the context of climatic change, more severe and long-lasting droughts will modify the fitness of plants, with potentially worse consequences on the relict trees. We have investigated the leaf phenotypic (anatomical, physiological and biochemical) plasticity in well-watered, drought- stressed and re-watered plants of two populations of Platanus orientalis, an endangered species in the west of the Mediterranean area. The two populations originated in contrasting climate (drier and warmer, Italy (IT) population; more humid and colder, Bulgaria (BG) population). The IT control plants had thicker leaves, enabling them to maintain higher leaf water content in the dry environment, and more spongy parenchyma, which could improve water conductivity of these plants and may result in easier CO2 diffusion than in BG plants. Control BG plants were also characterized by higher photorespiration and leaf antioxidants compared to IT plants. BG plants responded to drought with greater leaf thickness shrinkage. Drought also caused substantial reduction in photosynthetic parameters of both IT and BG plants. After re-watering, photosynthesis did not fully recover in either of the two populations. However, IT leaves became thicker, while photorespiration in BG plants further increased, perhaps indicating sustained activation of defensive mechanisms. Overall, our hypothesis, that plants with a fragmented habitat (i.e., the IT population) lose phenotypic plasticity but acquire traits allowing better resistance to the climate where they became adapted, remains confirmed
Evolution of dwarf early-type galaxies I. Spatially resolved stellar populations and internal kinematics of Virgo cluster dE/dS0 galaxies
Understanding the origin and evolution of dwarf early-type galaxies remains
an important open issue in modern astrophysics. Internal kinematics of a galaxy
contains signatures of violent phenomena which may have occurred, e.g. mergers
or tidal interactions, while stellar population keeps a fossil record of the
star formation history, therefore studying connection between them becomes
crucial for understanding galaxy evolution. Here, in the first paper of the
series, we present the data on spatially resolved stellar populations and
internal kinematics for a large sample of dwarf elliptical (dE) and lenticular
(dS0) galaxies in the Virgo cluster. We obtained radial velocities, velocity
dispersions, stellar ages and metallicities out to 1--2 half-light radii by
re-analysing already published long-slit and integral-field spectroscopic
datasets using the {\sc NBursts} full spectral fitting technique. Surprisingly,
bright representatives of the dE/dS0 class ( mag) look
very similar to intermediate-mass and giant lenticulars and ellipticals: (1)
their nuclear regions often harbour young metal-rich stellar populations always
associated with the drops in the velocity dispersion profiles; (2) metallicity
gradients in the main discs/spheroids vary significantly from nearly flat
profiles to -0.9 dex , i.e. somewhat 3 times steeper than for typical
bulges; (3) kinematically decoupled cores were discovered in 4 galaxies,
including two with very little, if any, large scale rotation. These results
suggest similarities in the evolutionary paths of dwarf and giant early-type
galaxies and call for reconsidering the role of major mergers in the dE/dS0
evolution.Comment: 22 pages, 3 tables, 29 figures, accepted to MNRA
Supporting IrO2 and IrRuOx nanoparticles on TiO2 and Nb-doped TiO2 nanotubes as electrocatalysts for the oxygen evolution reaction
IrO2 and IrRuOx (Ir:Ru 60:40 at%), supported by 50 wt% onto titania nanotubes (TNTs) and (3 at% Nb) Nb-doped titania nanotubes (Nb-TNTs), as electrocatalysts for the oxygen evolution reaction (OER), were synthesized and characterized by means of structural, surface analytical and electrochemical techniques. Nb doping of titania significantly increased the surface area of the support from 145 (TNTs) to 260 m2 g−1 (Nb-TNTs), which was significantly higher than those of the Nb-doped titania supports previously reported in the literature. The surface analytical techniques showed good dispersion of the catalysts onto the supports. The X-ray photoelectron spectroscopy analyses showed that Nb was mainly in the form of Nb(IV) species, the suitable form to behave as a donor introducing free electrons to the conduction band of titania. The redox transitions of the cyclic voltammograms, in agreement with the XPS results, were found to be reversible. Despite the supported materials presented bigger crystallite sizes than the unsupported ones, the total number of active sites of the former was also higher due to their better catalyst dispersion. Considering the outer and the total charges of the cyclic voltammograms in the range 0.1-1.4 V, stability and electrode potentials at given current densities, the preferred catalyst was IrO2 supported on the Nb-TNTs. The electrode potentials corresponding to given current densities were between the smallest ones given in the literature despite the small oxide loading used in this work and its Nb doping, thus making the Nb-TNTs-supported IrO2 catalyst a promising candidate for the OER. The good dispersion of IrO2, high specific surface area of the Nb-doped supports, accessibility of the electroactive centers, increased stability due to Nb doping and electron donor properties of the Nb(IV) oxide species were considered the main reasons for its good performance
UBVRI observations of the flickering of RS Ophiuchi at Quiescence
We report observations of the flickering variability of the recurrent nova RS
Oph at quiescence on the basis of simultaneous observations in 5 bands (UBVRI).
RS Oph has flickering source with (U-B)_0=-0.62 \pm 0.07, (B-V)_0=0.15 \pm
0.10, (V-R)_0=0.25 \pm 0.05. We find for the flickering source a temperature
T_fl = 9500 \pm 500 K, and luminosity L_fl = 50 - 150 L_sun (using a distance
of d=1.6kpc). We also find that on a (U-B) vs (B-V) diagram the flickering of
the symbiotic stars differs from that of the cataclysmic variables. The
possible source of the flickering is discussed. The data are available upon
request from the authors and on the web
www.astro.bas.bg/~rz/RSOph.UBVRI.2010.MNRAS.tar.gz.Comment: 7 pages, MNRAS (accepted
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