1,193 research outputs found

    Gardner optimal capacity of the diluted Blume-Emery-Griffiths neural network

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    The optimal capacity of a diluted Blume-Emery-Griffiths neural network is studied as a function of the pattern activity and the embedding stability using the Gardner entropy approach. Annealed dilution is considered, cutting some of the couplings referring to the ternary patterns themselves and some of the couplings related to the active patterns, both simultaneously (synchronous dilution) or independently (asynchronous dilution). Through the de Almeida-Thouless criterion it is found that the replica-symmetric solution is locally unstable as soon as there is dilution. The distribution of the couplings shows the typical gap with a width depending on the amount of dilution, but this gap persists even in cases where a particular type of coupling plays no role in the learning process.Comment: 9 pages Latex, 2 eps figure

    Obtención de jarabes glucosados por hidrólisis enzimática empleando almidón de sorgo CIAPR-132

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    La presente investigación está encaminada al estudio de la posible sustitución del maíz por el sorgo en la producción de jarabes glucosados para la industria alimenticia, considerando la evaluación de las potencialidades de dicho cereal. En este sentido se realizó un diseño experimental compuesto del tipo 2k, utilizando  el Software Statgraphics Centurion XV en elprocesamiento de los resultados del proceso desarrolladoen el laboratorio. Para ello se analizó la influenciade las variables independientes: concentración deenzima alfa amilasa (X1) en los niveles de 0,06 y 0,16%p/p, la concentración de enzima amiloglucosidasa(AMG) (X2) en los niveles de 0,18 y 0,375 %p/p ytiempo de sacarificación (X3) de 24 y 48 horas sobrelas variables respuestas °Brix y Azúcares ReductoresTotales (ART); además se determinó el rendimiento de cada experimento, obteniéndose los mejores resultados para la mayor concentración de enzima alfaamilasa, concentración de enzima AMG y tiempo de sacarificación en los menores valores. Los mejores resultados se obtuvieron para el Brix de 52,22 y ARTde 68,76%

    The nuclear and extended infrared emission of the Seyfert galaxy NGC 2992 and the interacting system Arp 245

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    We present subarcsecond resolution infrared (IR) imaging and mid-IR spectroscopic observations of the Seyfert 1.9 galaxy NGC 2992, obtained with the Gemini North Telescope and the Gran Telescopio CANARIAS (GTC). The N-band image reveals faint extended emission out to ~3 kpc, and the PAH features detected in the GTC/CanariCam 7.5-13 micron spectrum indicate that the bulk of this extended emission is dust heated by star formation. We also report arcsecond resolution MIR and far-IR imaging of the interacting system Arp 245, taken with the Spitzer Space Telescope and the Herschel Space Observatory. Using these data, we obtain nuclear fluxes using different methods and find that we can only recover the nuclear fluxes obtained from the subarcsecond data at 20-25 micron, where the AGN emission dominates. We fitted the nuclear IR spectral energy distribution of NGC 2992, including the GTC/CanariCam nuclear spectrum (~50 pc), with clumpy torus models. We then used the best-fitting torus model to decompose the Spitzer/IRS 5-30 spectrum (~630 pc) in AGN and starburst components, using different starburst templates. We find that, whereas at shorter mid-IR wavelengths the starburst component dominates (64% at 6 micron), the AGN component reaches 90% at 20 micron. We finally obtained dust masses, temperatures and star formation rates for the different components of the Arp 245 system and find similar values for NGC 2992 and NGC 2993. These measurements are within those reported for other interacting systems in the first stages of the interaction.Comment: 20 pages, 12 figures, accepted by MNRA

    Benchmarking recombinant Pichia pastoris for 3-hydroxypropionic acid production from glycerol

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    The use of the methylotrophic yeast Pichia pastoris (Komagataella phaffi) to produce heterologous proteins has been largely reported. However, investigations addressing the potential of this yeast to produce bulk chemicals are still scarce. In this study, we have studied the use of P. pastoris as a cell factory to produce the commodity chemical 3-hydroxypropionic acid (3-HP) from glycerol. 3-HP is a chemical platform which can be converted into acrylic acid and to other alternatives to petroleum-based products. To this end, the mcr gene from Chloroflexus aurantiacus was introduced into P. pastoris. This single modification allowed the production of 3-HP from glycerol through the malonyl-CoA pathway. Further enzyme and metabolic engineering modifications aimed at increasing cofactor and metabolic precursors availability allowed a 14-fold increase in the production of 3-HP compared to the initial strain. The best strain (PpHP6) was tested in a fed-batch culture, achieving a final concentration of 3-HP of 24.75 g l−1, a product yield of 0.13 g g−1 and a volumetric productivity of 0.54 g l−1 h−1, which, to our knowledge, is the highest volumetric productivity reported in yeast. These results benchmark P. pastoris as a promising platform to produce bulk chemicals for the revalorization of crude glycerol and, in particular, to produce 3-HP

    The starburst-AGN connection in the merger galaxy Mrk 938: an infrared and X-ray view

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    Mrk938 is a luminous infrared galaxy in the local Universe believed to be the remnant of a galaxy merger. It shows a Seyfert 2 nucleus and intense star formation according to optical spectroscopic observations. We have studied this galaxy using new Herschel far-IR imaging data in addition to archival X-ray, UV, optical, near-IR and mid-IR data. Mid- and far-IR data are crucial to characterise the starburst contribution, allowing us to shed new light on its nature and to study the coexistence of AGN and starburst activity in the local Universe. The decomposition of the mid-IR Spitzer spectrum shows that the AGN bolometric contribution to the mid-IR and total infrared luminosity is small (Lbol(AGN)/LIR~0.02), which agrees with previous estimations. We have characterised the physical nature of its strong infrared emission and constrained it to a relatively compact emitting region of <2kpc. It is in this obscured region where most of the current star formation activity is taking place as expected for LIRGs. We have used Herschel imaging data for the first time to constrain the cold dust emission with unprecedented accuracy. We have fitted the integrated far-IR spectral energy distribution and derived the properties of the dust, obtaining a dust mass of 3x10^7Msun. The far-IR is dominated by emission at 35K, consistent with dust heated by the on-going star formation activity.Comment: 12 pages, 6 figures, 4 tables, accepted for publication in MNRA

    Bis(tetra­methyl­amonium) bis­(2,4,5-carboxy­benzoate)–benzene-1,2,4,5-tetra­carboxylic acid (1/1)

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    The asymmetric unit of the title compound, 2C4H12N+·2C10H5O8 −·C10H6O8, consists of a tetra­methyl­amonium cation, an anion derived from the singly deprotonated pyromellitic acid anion, 2,4,5-carboxy­benzoate (H3bta−), and one-half of a benzene-1,2,4,5-tetra­carboxylic acid (H4bta) mol­ecule, which has the centroid of the aromatic ring positioned at a crystallographic centre of inversion. The H4bta and H3bta− residues are involved in an extensive inter­molecular O—H⋯O hydrogen-bonding network, which leads to a three-dimensional supra­molecular structure containing one-dimensional channels running parallel to the [001] crystallographic direction. These channels house the tetra­methyl­amonium cations

    Probing the Nuclear and Circumnuclear Activity of NGC1365 in the Infrared

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    We present new far-infrared (70-500micron) Herschel PACS and SPIRE imaging observations as well as new mid-IR Gemini/T-ReCS imaging (8.7 and 18.3micron) and spectroscopy of the inner Lindblad resonance (ILR) region (R<2.5kpc) of the spiral galaxy NGC1365. We complemented these observations with archival Spitzer imaging and spectral mapping observations. The ILR region of NGC1365 contains a Seyfert 1.5 nucleus and a ring of star formation with an approximate diameter of 2kpc. The strong star formation activity in the ring is resolved by the Herschel/PACS imaging data, as well as by the Spitzer 24micron continuum emission, [NeII]12.81micron line emission, and 6.2 and 11.3micron PAH emission. The AGN is the brightest source in the central regions up to lambda~24micron, but it becomes increasingly fainter in the far-infrared when compared to the emission originating in the infrared clusters (or groups of them) located in the ring. We modeled the AGN unresolved infrared emission with the CLUMPY torus models and estimated that the AGN contributes only to a small fraction (~5%) of the infrared emission produced in the inner ~5kpc. We fitted the non-AGN 24-500micron spectral energy distribution of the ILR region and found that the dust temperatures and mass are similar to those of other nuclear and circumnuclear starburst regions. Finally we showed that within the ILR region of NGC1365 most of the on-going star formation activity is taking place in dusty regions as probed by the 24micron emission.Comment: Accepted for publication in MNRA

    Compósitos de colagénio/apatite de origem marinha para aplicação em engenharia de tecidos mineralizados

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    Devido ao aumento de lesões associadas ao envelhecimento da população, a regeneração do tecido ósseo tem sido alvo de estudo. Apesar da vasta investigação neste sentido, os auto-enxertos continuam a prevalecer como tratamento de primeira linha, apesar das suas limitações. A extração de compostos de recursos marinhos para uso em abordagens de engenharia de tecidos emerge como uma alternativa promissora para regeneração de lesões ósseas. Neste capítulo apresenta-se um biomaterial promissor para aplicação em engenharia de tecidos duros tendo como base uma estratégia de valorização de sub-produtos marinhos, nomeadamente pele e dentes de tubarão.Os autores agradecem o apoio financeiro recebido da União Europeia através do Programa INTERREG—POCTEP, no âmbito dos Projetos 0687_NOVOMAR_1_P e 0245_IBEROS_1_E, através do Programa de cooperação transnacional Espaço Atlântico, no âmbito do Projeto MARMED (2011-1/164) e através do 7º Programa-Quadro de Investigação e Desenvolvimento Tecnológico (FP7), através do Projeto POLARIS (REGPOT-CT2012-316331). Os autores gostariam de agradecer também ao Centro Tecnológico del Mar (CETMAR, Vigo, Espanha) e COPEMAR SA (Espanha) pelo fornecimento dos subprodutos de tubarão. G.S.D agradece ao Programa Norte2020 (Portugal2020) pela bolsa de doutoramento (NORTE-08-5369-F SE-000044) e R.P. agradece à Fundação para a Ciência e a Tecnologia pelo contrato IF/00347/2015

    Resolving the nuclear dust distribution of the Seyfert 2 galaxy NGC 3081

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    We report far-infrared (FIR) imaging of the Seyfert 2 galaxy NGC 3081 in the range 70-500 micron, obtained with an unprecedented angular resolution, using the Herschel Space Observatory instruments PACS and SPIRE. The 11 kpc (~70 arcsec) diameter star-forming ring of the galaxy appears resolved up to 250 micron. We extracted infrared (1.6-500 micron) nuclear fluxes, that is active nucleus-dominated fluxes, and fitted them with clumpy torus models, which successfully reproduce the FIR emission with small torus sizes. Adding the FIR data to the near- and mid-infrared spectral energy distribution (SED) results in a torus radial extent of Ro=4(+2/-1) pc, as well as in a flat radial distribution of the clouds (i.e. the q parameter). At wavelengths beyond 200 micron, cold dust emission at T=28+/-1 K from the circumnuclear star-forming ring of 2.3 kpc (~15 arcsec) in diameter starts making a contribution to the nuclear emission. The dust in the outer parts of the galaxy is heated by the interstellar radiation field (19+/-3 K).Comment: 6 pages, 4 figures. Accepted for publication in MNRAS letter

    ¿CUÁN IMPORTANTES SON LOS BOSQUES SECOS PARA LAS URBANIZACIONES? EL CASO DE DAULE, ECUADOR

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    Global change and direct sun near the ecuador increase the temperature of cities whereas forests regulate such temperature. We therefore assessed the structure and above ground biomass of two forest remnants nearby a newly built urbanization in Daule, Ecuador (Daule 1-2). We made n=5 transects (25 m × 4 m) covering 0.05 ha/site, then measured all trees ≥2.5 cm dbh (1.3 m above ground level) and compared with other forests studied by Alwyn Gentry. Daule-1 and Daule-2 had 39 and 35 individuals, respectively whereas Gentry found 159 and 216 individuals at Capeira and Esmeraldas. The densities for our n=5 transects (average ± standard error) were smaller for (Daule-1=780±37.42 ind/ha) and (Daule-2=740±40.00 ind/ha) while Capeira and Esmeraldas (n=10 transects for each site) which had (2270±211.37 ind/ha) and (3540±265.50 ind/ha), respectively (ANOVA, P&lt;0.001). The carbon captured was Daule-1=131.6 Mg/ha, Daule-2=111.7 Mg/ha, Daule-1+Daule-2=243.3 Mg/ha likewise Capeira 210.6 Mg / ha and Esmeraldas 181.5 Mg / ha. Such results suggest that forest remnants play an important role for people’s life quality by capturing carbon dioxide and producing oxygen; role they would play better if the forests would have more extensive.El calentamiento global y el sol directo cerca del ecuador aumentan la temperatura en las ciudades, mientras que los bosques son los encargados de regular dicha temperatura. Evaluamos la estructura y biomasa aérea de dos remanentes de bosques cerca de una urbanización en construcción en Daule, Ecuador (Daule 1-2). Se tomaron n=5 transectos (25 m x 4 m) cubriendo 0.05 ha/sitio, medimos todos los árboles ≥2,5 cm dap (1.3 m sobre el nivel del suelo) y comparamos con otros bosques estudiados por Alwyn Gentry. Daule-1 y Daule-2 tenían 39 y 35 individuos, respectivamente, mientras que Gentry encontró 159 y 216 individuos en Capeira y Esmeraldas. La densidad en los n=5 transectos (promedio ± error estándar) fueron menores para (Daule-1=780±37.42 ind/ha) y (Daule-2=740±40.00 ind/ha) en tanto que Capeira y Esmeraldas (n=10 transectos para cada sitio) tuvieron (2270±211.37 ind/ha) y (3540±265.50 ind/ha), respectivamente (ANOVA, P&lt;0.001). El carbono capturado fueDaule-1=131.6 Mg/ha, Daule-2=111.7 Mg/ha, Daule-1+Daule-2=243.3Mg/ha así mismo Capeira 210.6 Mg/ha y Esmeraldas 181.5 Mg/ha. Tales resultados sugieren que los remanentes de bosques juegan un papel importante para la calidad de vida de las personas al capturar dióxido de carbono y producir oxígeno; papel que jugarían mejor si los bosques fueran más extensos. &nbsp
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