Nambu-Jona-Lasinio Model in Curved Spacetime with Magnetic Field

We discuss the phase structure of the NJL model in curved spacetime with magnetic field using $1/N$-expansion and linear curvature approximation. The effective potential for composite fields $\bar\psi \psi$ is calculated using the proper-time cut-off in the following cases: a) at non-zero curvature, b) at non-zero curvature and non-zero magnetic field, and c) at non-zero curvature and non-zero covariantly constant gauge field. Chiral symmetry breaking is studied numerically. We show that the gravitational field may compensate the effect of the magnetic field what leads to restoration of chiral symmetry.Comment: LaTex file, 11 pages, 5 figures (not included) avaliable by request from first or third autho

Dark energy from scalar field with Gauss Bonnet and non-minimal kinetic coupling

We study a model of scalar field with a general non-minimal kinetic coupling to itself and to the curvature, and additional coupling to the Gauss Bonnet 4-dimensional invariant. The model presents rich cosmological dynamics and some of its solutions are analyzed. A variety of scalar fields and potentials giving rise to power-law expansion have been found. The dynamical equation of state is studied for two cases, with and without free kinetic term . In both cases phenomenologically acceptable solutions have been found. Some solutions describe essentially dark energy behavior, and and some solutions contain the decelerated and accelerated phases.Comment: 21 page

Potencial nutritivo de la harina de arroz en pollos de engorde.

En la Sabana de Bogotá se efectúan 4 experimentos con el fín de determinar, en pollos de engorde, la energía metabolizable y la calidad proteíca del maíz, sorgo y harina de arroz y establecer el nivel óptimo de reemplazo de las calorías metabolizables de los 2 cereales por calorías del subproducto. El ensayo 1 se realiza con 96 machos Ross de 2 semanas de edad y los valores de energía metabolizable encontrados fueron: 3297; 3060 y 3275 Mcal/kg para el maíz, sorgo y harina de arroz, respectivamente. Los resultados en la evaluación de la calidad proteíca: 71.57 y 70.31 para el maíz; 51.34 y 51.10 para el sorgo y 48.85 y 47.86 para la harina de arroz. Al sustituir hasta un 75 por ciento de calorías de maiz y sorgo por energia de la harina de arroz, la ganancia de peso fue similar a los controles que no recibían este subproducto. En el experimento con maíz y/o harina de arroz, la máxima eficiencia en la utilización de alimento se consiguió hasta un nivel de reemplazo de la energía de maíz por calorias de la harina de arroz del 25 por ciento. Se concluye que la harina de arroz por su contenido de energía metabolizable semejante a la del maíz y superior al sorgo, puede ser utilizada en sustitución de estos cereales hasta un 75 por ciento de su aporte energético. En dietas de maíz la máxima eficiencia alimenticia se consigue con un nivel máximo de reemplazo del 25 por cientoArroz-Oryza sativaMaestría en CienciasMaestrí

Asymmetric embedding in brane cosmology

We derive a system of cosmological equations for a braneworld with induced curvature which is a junction between several bulk spaces. The permutation symmetry of the bulk spaces is not imposed, and the values of the fundamental constants, and even the signatures of the extra dimension, may be different on different sides of the brane. We then consider the usual partial case of two asymmetric bulk spaces and derive an exact closed system of scalar equations on the brane. We apply this result to the cosmological evolution on such a brane and describe its various partial cases.Comment: 10 page

An autonomous organic reaction search engine for chemical reactivity

The exploration of chemical space for new reactivity, reactions and molecules is limited by the need for separate work-up-separation steps searching for molecules rather than reactivity. Herein we present a system that can autonomously evaluate chemical reactivity within a network of 64 possible reaction combinations and aims for new reactivity, rather than a predefined set of targets. The robotic system combines chemical handling, in-line spectroscopy and real-time feedback and analysis with an algorithm that is able to distinguish and select the most reactive pathways, generating a reaction selection index (RSI) without need for separate work-up or purification steps. This allows the automatic navigation of a chemical network, leading to previously unreported molecules while needing only to do a fraction of the total possible reactions without any prior knowledge of the chemistry. We show the RSI correlates with reactivity and is able to search chemical space using the most reactive pathways

Synthesis and structural characterization of trans-bis[1,3-bis(methoxy- ethyl)-4,5-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene]dichloro- palladium(II)

A Pd(II) complex of a new N-heterocyclic carbene (NHC) ligand with bulky substituents and functionalized methoxy-donor side arms has been synthesized and characterized by elemental analyses, 1H and 13C NMR, and IR spectroscopy. Molecular and crystal structures of the title complex have been determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P21/c, with a = 15.927(2), b = 8.489(2), c = 20.309(5) Å, β = 99.213(2)°, Z = 2, Dx = 1.253 g cm-3. The palladium atom is situated on an inversion center. There are several weak intramolecular C-H⋯N/O interactions. © 2007 Verlag der Zeitschrift für Naturforschung

Reconstruction of modified gravity with ghost dark energy models

In this work, we reconstruct the $f(R)$ modified gravity for different ghost and generalized ghost dark energy models in FRW flat universe, which describe the accelerated expansion of the universe. The equation of state of reconstructed $f(R)$ - gravity has been calculated. We show that the corresponding $f(R)$ gravity of ghost dark energy model can behave like phantom or quintessence. We also show that the equation of state of reconstructed $f(R)$ gravity for generalized ghost model can transit from quintessence regime to the phantom regime as indicated by recent observations.Comment: 13 pages, some references and one author are added. Accepted for publication by MPL

Non-minimal kinetic coupling and Chaplygin gas cosmology

In the frame of the scalar field model with non minimal kinetic coupling to gravity, we study the cosmological solutions of the Chaplygin gas model of dark energy. By appropriately restricting the potential, we found the scalar field, the potential and coupling giving rise to the Chaplygin gas solution. Extensions to the generalized and modified Chaplygin gas have been made.Comment: 18 pages, 2 figures. To appear in EPJ

A new Colombian pest species of the genus \u3ci\u3ePoecilocloeus\u3c/i\u3e Bruner (Orthoptera: Acrididae: Proctolabinae) on coffee, with a key to the Neotropical species

A remarkable new species of Poecilocloeus (Orthoptera: Acrididae: Proctolabinae) found damaging coffee plantations in the Western Andes of Colombia is described and named P. coffeaphilus n. sp. This new species is part of a distinct and colorful group of Proctolabinae grasshoppers, with most species found at low altitudes in the rainforest of the Amazon basin. In contrast, the new species is found at elevations of 1600 to 1800 m in the canopy of dense cloud forests, in the southwestern part of the department of Antioquia (Western Cordillera, Colombian Andes). Information about the natural history, behavior, natural enemies and control strategies in coffee plantations is given for this new species of masked grasshopper. A key to the Neotropical species of the fruticolus species group is presented. Una nueva y notable especie de Poecilocloeus (Orthoptera: Acrididae: Proctolabinae) encontrada afectando plantaciones de café en la cordillera occidental de Colombia es descrita y nombrada como P. coffeaphilus. La nueva especie hace parte de un grupo distintivo y colorido de saltamontes de la subfamilia Proctolabinae, con la mayoría de especies distribuidas a bajas altitudes en las selvas lluviosas de la cuenca amazónica. Por el contrario, la nueva especie se encuentra a altitudes entre 1.600 a 1.800 m en el dosel del bosque nublado, en el suroeste del departamento de Antioquia (Andes colombianos, Cordillera Occidental). Se da información acerca de la historia natural, comportamiento, enemigos naturales y estrategias de control de esta nueva especie de saltamonte enmascarado en cultivos de café. Se presenta una clave para las especies del grupo fruticolus de la región Neotropical

Mencegah Pembentukan Kalsium Sulfat pada Desalinasi Air Laut

Resin penukar-anion, Relite MG 1/P, dapat digunakan untuk memisahkan sulfat dalam air laut guna mencegah pembentukan kerak kalsium sulfat pada heat exchanger. Resin tersebut menunjukkan selektivitas sulfat yang tinggi dalam air laut sintetis. Resin yang telah dipakai dapat diregenerasi menggunakan air asin yang dipekatkan dengan asam hingga mencapai pH 4. Untuk waktu pemakaian dan regenerasi yang sama, faktor konsentrasi desalinasi (misalnya 2 hingga 4) menaikkan konsentrasi klorida dalam air asin yang diblowdown. Dengan faktor konsentrasi yang tetap, kenaikan laju alir (pengurangan waktu pemakaian dan regenerasi) memperendah efisiensi regenerasi dan menaikkan pemisahan sulfat. Akibat kelarutan kalsium sulfat yang bersifat terbalik tersebut, temperatur air asin yang tinggi memerlukan pemisahan sulfat yang lebih banyak, yang dapat dicapai dengan mengurangi laju alir air laut. Pengurangan laju alir tersebut membutuhkan peralatan yang lebih besar dan resin yang lebih banyak, sehingga biaya modal bertambah. Untuk pabrik desalinasi dengan kapasitas produksi 1 juta gallon per hari dan faktor konsentrasi sebesar 2, biaya pemisahan sulfat meliputi biaya resin dan biaya peralatan. Biaya tersebut bervariasi dari $0.246 hingga$0.356/kgalon (per ribu galon air yang diproduksi) karena temperatur maksimum air asin berubah dari 140°C menjadi 180°C. Keywords: desalinasi air laut, ion exchange, kalsium sulfat, kerak; mechanical vapor compression (MVC), pemisahan sulfat, resin penukar-anion basa lema