1,301 research outputs found
Sobre condiciones de integrabilidad de una estructura j satisfaciendo (j2-p2) (j2 +q2 ) = 0
We consider the structures defined by a tensor field J of type (1,1) which satisfy the condition (J2-p2)(J2+q2)=0 characterizing its integrability in term of its Nijenhuis tenso
A high order -difference equation for -Hahn multiple orthogonal polynomials
A high order linear -difference equation with polynomial coefficients
having -Hahn multiple orthogonal polynomials as eigenfunctions is given. The
order of the equation is related to the number of orthogonality conditions that
these polynomials satisfy. Some limiting situations when are studied.
Indeed, the difference equation for Hahn multiple orthogonal polynomials given
in \cite{Lee} is corrected and obtained as a limiting case
Non-equilibrium Quantum Spin Dynamics from 2PI Functional Integral Techniques in the Schwinger Boson Representation
We present a non-equilibrium quantum field theory approach to the
initial-state dynamics of spin models based on two-particle irreducible (2PI)
functional integral techniques. It employs a mapping of spins to Schwinger
bosons for arbitrary spin interactions and spin lengths. At next-to-leading
order (NLO) in an expansion in the number of field components, a wide range of
non-perturbative dynamical phenomena are shown to be captured, including
relaxation of magnetizations in a 3D long-range interacting system with
quenched disorder, different relaxation behaviour on both sides of a quantum
phase transition and the crossover from relaxation to arrest of dynamics in a
disordered spin chain previously shown to exhibit many-body-localization. Where
applicable, we employ alternative state-of-the-art techniques and find rather
good agreement with our 2PI NLO results. As our method can handle large system
sizes and converges relatively quickly to its thermodynamic limit, it opens the
possibility to study those phenomena in higher dimensions in regimes in which
no other efficient methods exist. Furthermore, the approach to classical
dynamics can be investigated as the spin length is increased
Short-term effects on soil properties and wheat production from secondary paper sludge application on two Mediterranean agricultural soils
This study was conducted under greenhouse conditions to evaluate the potential use of SPS as a fertilizer, amendment and/or liming
agent for wheat (Triticum aestivum L.). Two representative Mediterranean agricultural soils, a Cambic Arenosol (cmAR) and a Cromic
Cambisol (crCM) were used. Treatments included four sludge rates ranging from 0 to 40 g kg 1 (equivalent of 0, 38, 88 and
120 Mg ha 1). A significant increment in soil pH, organic carbon, N total, available P and exchangeable K were observed in both soils.
Sludge application significantly increased N and decreased Zn, Mn and Cu concentrations in wheat. Wheat grain yields were reduced by
33% and 37% when 120 Mg SPS ha 1 was applied to cmAR and crCM soils, respectively, due apparently to unavailability of Mg. However,
straw yields, with much lower Mg requirements, increased significantly with SPS rates. Secondary pulp mill sludge seems to be a
potential source of organic matter, N, P, K and a potential soil amendment liming agent for acid soils, when appropriate supplemental
fertilizer was provided. For grain crops grown in these soils, addition of Mg is required for proper nutrient balance
A large cockroach from the mesosaurbearing Konservat-Lagerstätte (Mangrullo Formation), Late Paleozoic of Uruguay
Barona arcuata, n.gen et n.sp., a left forewing of a relatively large cockroach of the Order Blattaria, is described from mesosaur-bearing lagoonal shales of the Mangrullo Formation (north-eastern Uruguay). While most of the insect remains recovered from the Mangrullo Formation come from sandy limestones, associated to scarce isolated mesosaur bones and pygocephalomorph crustaceans, the cockroach wing here described was found in the overlaying green to brownish, gray and dark black shales associated to intercalated bentonites and evaporitic gypsum crystals. Barona arcuata shares some features with typical Late Carboniferous taxa such as its general venation pattern and outline of the wing, four main and powerful veins arising close together from near the base of the wing, Sc simple forked, pectinate, reaching the costal border through a long fork, R and M bifurcating and terminating in the wing margin above and below the apex respectively, short and narrow CuA, and the presence of a broad interspace between CuP and AA. Cross venation seems to be absent or it was not preserved. Some characters might relate Barona arcuata to the Late CarboniferousEarly Permian Neothroblattinidae such as the presence of sigmoidal veins in the anal area, a condition not found in any of the remaining representatives of the Palaeozoic Blattaria. Intriguingly, the Uruguayan blattarian also presents a strong similarity with Qilianiblatta namurensis Zhang, Schneider & Hong, 2012 from the Westphalian of China, clearly a smaller taxon that is also difficult to relate to any of the preexistent families. The apparent plesiomorphic venation pattern of the new species which is reminiscent of that present in the oldest known blattarians, is in agreement with a Permo-Carboniferous (Gzhelian-Asselian) age for the Mangrullo Formation also supported by the presence of a macrofloral assemblage dominated by arborescent lepidondendrids and other lycopsids and the pygocephalid-like morphology of the pygocephalomorph crustaceans from the same levels
Dithiothreitol increases f3-glucuronidase accumulation in transformed tobacco (Nicotiana tabacum) protoplasts without altering their viability or the synthesis and export of cellular proteins
The effect of dithiothreitol (DTT) on the expression of the β-glucuronidase (GUS) reporter gene under the control of the CaMV-35 S promoter has been investigated by radioactive labelling and immunoprecipitation of the enzyme in protoplasts from stably transformed tobacco plants and compared with that observed in protoplasts transiently expressing the same gene construct. An increase in net accumulation of GUS during the culture period in response to externally added DTT (2 mm) was observed both in protoplasts from transformed tobacco plants and in electroporated protoplasts. DTT had no effect on rate of degradation of the mature GUS protein, as shown in a pulse-chase experiment. Relevant aspects of protoplast physiology, such as viability, synthesis of 35S-labelled cellular proteins, or synthesis and export of pathogenesis-related proteins (one putative chitinase and two 1,3-β-glucanases) were not affected by the reducing reagen
Enhanced dimerization of TiOCl under pressure: spin-Peierls - to - Peierls transition
We report high-pressure x-ray diffraction and magnetization measurements
combined with ab-initio calculations to demonstrate that the high-pressure
optical and transport transitions recently reported in TiOCl, correspond in
fact to an enhanced Ti3+-Ti3+ dimerization existing already at room
temperature. Our results confirm the formation of a metal-metal bond between
Ti3+ ions along the b-axis of TiOCl, accompanied by a strong reduction of the
electronic gap. The evolution of the dimerization with pressure suggests a
crossover from the spin-Peierls to a conventional Peierls situation at high
pressures.Comment: 9pages, 4 figure
Pressure-induced metal-insulator transition in MgV_2O_4
On the basis of experimental thermoelectric power results and ab initio
calculations, we propose that a metal-insulator transition takes place at high
pressure (approximately 6 GPa) in MgV_2O_4.Comment: 2 pages, 3 figures, accepted in Physica B (Strongly Correlated
Electron Systems '07
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