261 research outputs found
Effects due to a scalar coupling on the particle-antiparticle production in the Duffin-Kemmer-Petiau theory
The Duffin-Kemmer-Petiau formalism with vector and scalar potentials is used
to point out a few misconceptions diffused in the literature. It is explicitly
shown that the scalar coupling makes the DKP formalism not equivalent to the
Klein-Gordon formalism or to the Proca formalism, and that the spin-1 sector of
the DKP theory looks formally like the spin-0 sector. With proper boundary
conditions, scattering of massive bosons in an arbitrary mixed vector-scalar
square step potential is explored in a simple way and effects due to the scalar
coupling on the particle-antiparticle production and localization of bosons are
analyzed in some detail
Estabilidad oxidativa de aceites de soja y maíz enriquecidos con extracto hidroalcohólico de Pluchea quitoc
Soybean and corn oils are among the most popular vegetable oils, and are ingredients which are widely used in cooking and in the food industry. These oils contain many unsaturated fatty acids such as oleic, linoleic and linolenic acids, which makes them easily oxidized by oxygen. Extensive efforts are being made to prevent or minimize vegetable oil oxidation through the development of antioxidants. Phenolic antioxidants which are present in some extracts can be used as food additives to prevent lipid oxidation. In this study chromatographic analyses (HPLC and GC) of the Pluchea quitoc hydroalcoholic extract were performed. The content of phenolic compounds by the Folin-Ciocalteau method and the antioxidant properties against radicals 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) were also evaluated. The effect of samples prepared with soybean and corn oils enriched with Pluchea quitoc hydroalcoholic extract was determined and compared with samples of these oils which were free of antioxidants and with samples containing the synthetic antioxidant BHT. The results showed potential for application of the extract. A high content of phenolic compounds (314 milligrams of gallic acid equivalents (GAE)/g of extract) and good IC50 values were detected for the inhibition of the radicals DPPH and ABTS (13.2 µg·mL-1 and 5.6 µg·mL-1). In the evaluation of the oxidative stability of the oils enriched with this extract, it was found that at 1% concentration it was possible to obtain values of induction period (IP) close to the samples with added BHT.Los aceites de soja y maíz se encuentran entre los aceites vegetales más populares, ingredientes ampliamente utilizados en la cocina y también en la industria alimentaria. Estos aceites contienen muchos ácidos grasos insaturados como los ácidos oleico, linoleico y linolénico que se oxidan fácilmente con el oxígeno. Se están realizando grandes esfuerzos para prevenir o minimizar la oxidación de los aceites vegetales mediante el desarrollo de antioxidantes. Los antioxidantes fenólicos presentes en algunos extractos se pueden utilizar como aditivos alimentarios para prevenir la oxidación de lípidos. En este estudio se realizó la obtención y análisis cromatográficos (HPLC y GC) del extracto hidroalcohólico de Pluchea quitoc. El contenido de compuestos fenólicos se evaluó por el método de Folin-Ciocalteau y las propiedades antioxidantes frente a radicales DPPH y ABTS. Se determinó el efecto de muestras preparadas con aceites de soja y maíz enriquecidas con extracto hidroalcohólico de Pluchea quitoc y se comparó con muestras de estos aceites libres de antioxidantes y con el antioxidante sintético BHT. Los resultados mostraron potencial para la aplicación del extracto. Se detectó un alto contenido de compuestos fenólicos (314 mg GAE) y buenos valores de IC50 para la inhibición de los radicales DPPH y ABTS (13.2 µg·mL-1 y 5.6 µg·mL-1). En la evaluación de la estabilidad oxidativa de los aceites enriquecidos con este extracto, se encontró que para la concentración del 1% es posible obtener valores de período de inducción (IP) cercanos a las muestras adicionadas con BHT
Approximate solution of the Duffin-Kemmer-Petiau equation for a vector Yukawa potential with arbitrary total angular momenta
The usual approximation scheme is used to study the solution of the
Duffin-Kemmer-Petiau (DKP) equation for a vector Yukawa potential in the
framework of the parametric Nikiforov-Uvarov (NU) method. The approximate
energy eigenvalue equation and the corresponding wave function spinor
components are calculated for arbitrary total angular momentum in closed form.
Further, the approximate energy equation and wave function spinor components
are also given for case. A set of parameter values is used to obtain the
numerical values for the energy states with various values of quantum levelsComment: 17 pages; Communications in Theoretical Physics (2012). arXiv admin
note: substantial text overlap with arXiv:1205.0938, and with
arXiv:quant-ph/0410159 by other author
Quasinormal modes for tensor and vector type perturbation of Gauss Bonnet black holes using third order WKB approach
We obtain the quasinormal modes for tensor perturbations of Gauss-Bonnet (GB)
black holes in dimensions and vector perturbations in
and 8 dimensions using third order WKB formalism. The tensor perturbation for
black holes in is not considered because of the fact that it is unstable
to tensor mode perturbations. In the case of uncharged GB black hole, for both
tensor and vector perturbations, the real part of the QN frequency increases as
the Gauss-Bonnet coupling () increases. The imaginary part first
decreases upto a certain value of and then increases with
for both tensor and vector perturbations. For larger values of , the
QN frequencies for vector perturbation differs slightly from the QN frequencies
for tensorial one. It has also been shown that as , the
quasinormal mode frequency for tensor and vector perturbation of the
Schwarzschild black hole can be obtained. We have also calculated the
quasinormal spectrum of the charged GB black hole for tensor perturbations.
Here we have found that the real oscillation frequency increases, while the
imaginary part of the frequency falls with the increase of the charge. We also
show that the quasinormal frequencies for scalar field perturbations and the
tensor gravitational perturbations do not match as was claimed in the
literature. The difference in the result increases if we increase the GB
coupling.Comment: 17 pages, 11 figures, change in title and abstract, new equations and
results added for QN frequencies for vector perturbations, new referencees
adde
Changes in selected haematological parameters associated with JAK1/JAK2 inhibition observed in patients with rheumatoid arthritis treated with baricitinib
Objective To characterise changes in selected haematological parameters following once-daily oral baricitinib dosing.Methods Data were pooled from eight randomised clinical trials (four phase 3, three phase 2, one phase 1b) and one long-term extension. Changes in haematological parameters were evaluated up to 128 weeks (N=2387); overall safety of baricitinib was assessed up to 6 years (N=3492).Results Mean absolute neutrophil counts decreased (-1.36x10(9)/L) within 1 month, followed by stabilisation within the normal reference range through week 128. The incidence of serious infections was not elevated in patients with neutropenia during the 24-week placebo-controlled period. Mean lymphocyte counts increased (+0.30x10(9)/L) within 1 month, then decreased to baseline (weeks 12-24). Mean platelet counts increased at week 2 (+51x10(9)/L), then decreased towards baseline. Overall, mean haemoglobin concentrations decreased (-0.12 mmol/L), then returned to baseline; however, reduced baseline haemoglobin concentrations observed in the highest baseline high-sensitivity C reactive protein quartile increased over time. Permanent drug discontinuation occurred due to laboratory abnormalities related to neutrophil count in 8 (0.2%), lymphocyte counts in 6 (0.2%), platelet counts in 8 (0.2%), and haemoglobin levels in 16 (0.5%) of all baricitinib-treated patients (N=3492 with 7993 total person-years of exposure).Conclusions Moderate decreases in neutrophils were seen during baricitinib treatment; however, serious infection was uncommon in patients with neutropenia. Transient increases were observed in lymphocytes and platelets, which returned to baseline over time. Changes in haemoglobin concentration were generally small. Haematological abnormalities seldom led to drug discontinuation.Pathophysiology and treatment of rheumatic disease
From chemical gardens to chemobrionics
Chemical gardens are perhaps the best example in chemistry of a
self-organizing nonequilibrium process that creates complex
structures. Many different chemical systems and materials can
form these self-assembling structures, which span at least 8
orders of magnitude in size, from nanometers to meters. Key to
this marvel is the self-propagation under fluid advection of
reaction zones forming semipermeable precipitation membranes
that maintain steep concentration gradients, with osmosis and
buoyancy as the driving forces for fluid flow. Chemical gardens
have been studied from the alchemists onward, but now in the
21st century we are beginning to understand how they can lead
us to a new domain of self-organized structures of semipermeable
membranes and amorphous as well as polycrystalline solids
produced at the interface of chemistry, fluid dynamics, and
materials science. We propose to call this emerging field
chemobrionics
The structure of the Yang-Mills spectrum for arbitrary simple gauge algebras
The mass spectrum of pure Yang-Mills theory in 3+1 dimensions is discussed
for an arbitrary simple gauge algebra within a quasigluon picture. The general
structure of the low-lying gluelump and two-quasigluon glueball spectrum is
shown to be common to all algebras, while the lightest three-quasigluon
glueballs only exist when the gauge algebra is A, that is in
particular . Higher-lying glueballs are shown to
exist only for the A, D and E gauge
algebras. The shape of the static energy between adjoint sources is also
discussed assuming the Casimir scaling hypothesis and a funnel form; it appears
to be gauge-algebra dependent when at least three sources are considered. As a
main result, the present framework's predictions are shown to be consistent
with available lattice data in the particular case of an
gauge algebra within 't Hooft's large- limit.Comment: 21 pages, 4 figures; remarks added, typos corrected in v2. v3 to
appear in EPJ
Tailoring therapies—improving the management of early breast cancer: St Gallen International Expert Consensus on the Primary Therapy of Early Breast Cancer 2015
The 14th St Gallen International Breast Cancer Conference (2015) reviewed new evidence on locoregional and systemic therapies for early breast cancer. This manuscript presents news and progress since the 2013 meeting, provides expert opinion on almost 200 questions posed to Consensus Panel members, and summarizes treatment-oriented classification of subgroups and treatment recommendation
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