Organic Molecules in the Galactic Center. Hot Core Chemistry without Hot Cores

We study the origin of large abundances of complex organic molecules in the Galactic center (GC). We carried out a systematic study of the complex organic molecules CH3OH, C2H5OH, (CH3)2O, HCOOCH3, HCOOH, CH3COOH, H2CO, and CS toward 40 GC molecular clouds. Using the LTE approximation, we derived the physical properties of GC molecular clouds and the abundances of the complex molecules.The CH3OH abundance between clouds varies by nearly two orders of magnitude from 2.4x10^{-8} to 1.1x10^{-6}. The abundance of the other complex organic molecules relative to that of CH3OH is basically independent of the CH3OH abundance, with variations of only a factor 4-8. The abundances of complex organic molecules in the GC are compared with those measured in hot cores and hot corinos, in which these complex molecules are also abundant. We find that both the abundance and the abundance ratios of the complex molecules relative to CH3OH in hot cores are similar to those found in the GC clouds. However, hot corinos show different abundance ratios than observed in hot cores and in GC clouds. The rather constant abundance of all the complex molecules relative to CH3OH suggests that all complex molecules are ejected from grain mantles by shocks. Frequent (similar 10^{5}years) shocks with velocities >6km/s are required to explain the high abundances in gas phase of complex organic molecules in the GC molecular clouds. The rather uniform abundance ratios in the GC clouds and in Galactic hot cores indicate a similar average composition of grain mantles in both kinds of regions. The Sickle and the Thermal Radio Arches, affected by UV radiation, show different relative abundances in the complex organic molecules due to the differentially photodissociation of these molecules.Comment: 18 pages, 10 Postscript figures, uses aa.cls, aa.bst, 10pt.rtx, natbib.sty, revsymb.sty revtex4.cls, aps.rtx and aalongtabl.sty. Accepted in A&A 2006. version 2. relocated figures and tables. Language editor suggestions. added reference

The central parsecs of M87: jet emission and an elusive accretion disc

We present the first simultaneous spectral energy distribution (SED) of M87 core at a scale of 0.4 arcsec ($\sim 32\, \rm{pc}$) across the electromagnetic spectrum. Two separate, quiescent, and active states are sampled that are characterized by a similar featureless SED of power-law form, and that are thus remarkably different from that of a canonical active galactic nuclei (AGN) or a radiatively inefficient accretion source. We show that the emission from a jet gives an excellent representation of the core of M87 core covering ten orders of magnitude in frequency for both the active and the quiescent phases. The inferred total jet power is, however, one to two orders of magnitude lower than the jet mechanical power reported in the literature. The maximum luminosity of a thin accretion disc allowed by the data yields an accretion rate of $< 6 \times 10^{-5}\, \rm{M_\odot \, yr^{-1}}$, assuming 10% efficiency. This power suffices to explain M87 radiative luminosity at the jet-frame, it is however two to three order of magnitude below that required to account for the jet's kinetic power. The simplest explanation is variability, which requires the core power of M87 to have been two to three orders of magnitude higher in the last 200 yr. Alternatively, an extra source of power may derive from black hole spin. Based on the strict upper limit on the accretion rate, such spin power extraction requires an efficiency an order of magnitude higher than predicted from magnetohydrodynamic simulations, currently in the few hundred per cent range.Comment: 18 pages, 6 figures. Accepted for publication in MNRA

Split-then-Combine Method for out-of-sample Combinations of Forecasts

Relative forecast performance of forecast units may periodically evolve over time. Therefore, it is desirable to take into account their forecast periodicity when forming forecast combinations. When dealing with small samples and small number of models, using panels is an efficient way of pulling out the additional information provided by that periodicity in the data. We capture this periodic information with different weights at different periods that we then keep in the out-of-sample combination. As in the simple average, we do not estimate weights, but instead compute them from panels of forecasts taken as given data. Empirical and bootstrap exercises illustrate the superiority of this method over fixed weight scheme

C-S-H gels in blended cements: Study by infrared spectroscopy

ICCC 2015, Beijing, China, 13~16 October 2015; http://iccc2015.csp.escience.cn/dct/page/1C-S-H gel is the main product in the Portland cement (PC) hydration. Of their structure and composition depends the cement properties (strength, durability¿). The mixes of others materials with PC provides new cementitious materials with different properties. Understand the changes produces in the hydration products in these blends improves their use. This work studies the changes produced in the C-S-H gel by means Fourier Transform Infrared Spectroscopy (FTIR). Several samples were studied, PC (as reference system), a system formed by PC and calcium aluminate cement (CAC) with a 75/25 ratio, and two system formed by PC, CAC and calcium sulfate (C¿) with an 85/15 ratio of PC/CAC with 3 and 5% of C¿. All samples were cured in two environmental; at the air and under water, in order to observe the influence of curing. The samples were studied at the 6 hours, 7 days, 12 and 32 months of age. Results show in the PC, it changes to lower wavenumbers in the Q2 units positions over time. This fact indicates a little transformation of structure like-tobermorite to structure like-jennite providing a C-S-H less compact. Addition of CAC in PC hydration decreases the migration of Q2 units to lower wavenumbers indicating that C-S-H structure is more compact in this case. When C¿ is included in the system, this migration of Q2 units is lower and the bands are sharper indicating the structure like tobermorite presence. Other effect visible in the spectra is the decrease of bands due to Q1 units with the addition of CAC. The greater presence of aluminates in the system provides substitutions of Si4+ by Al3+ in the C-S-H structure. This fact produces longer chains reducing the units Q1. Different behaviors are observed in the cured conditions showing higher transformation towards structures like-jennite in the samples cured under water. Several conclusions can be drawn of this work. First, it use of infrared spectroscopy as powerful tool in the cement chemistry field. Not only as characterization technique but also it can be used for obtain structural information about cement phases, both hydrated as anhydrous. Regarding addition of other hydraulic materials at PC, the study shows formation of C-S-H more compact that will provide better mechanical properties. Also the cured conditions have influenced about hydrated products structure.Peer Reviewe

TOY: A System for Experimenting with Cooperation of Constraint Domains

AbstractThis paper presents, from a user point-of-view, the mechanism of cooperation between constraint domains that is currently part of the system TOY, an implementation of a constraint functional logic programming scheme. This implementation follows a cooperative goal solving calculus based on lazy narrowing. It manages the invocation of solvers for each domain, and projection operations for converting constraints into mate domains via mediatorial constraints. We implemented the cooperation among Herbrand, real arithmetic (R), finite domain (FD) and set (S) domains. We provide two mediatorial constraints: The first one relates the numeric domains FD and R, and the second one relates FD and S

Geopolítica e hidrocarburos: Las prospecciones petrolíferas en el área canario-sahariana (1940-1980)

The Canary-Saharan area occupies a very particular region that has historically aroused a considerable socio-economic interest, first because it is the intersection of several trade routes, the productivity of their fishing grounds and the existence of large deposits of hydrocarbons. This last resource has aroused the ambition of the big European and North-American transnationals for decades. This article is to highlight the great historical journey that the searching of hydrocarbons has taken in the area, stopping in the period 1940-1980.El área canario-sahariana ocupa una zona muy particular que ha despertado históricamente un notable interés socioeconómico. En primer lugar por ser la intersección de varias rutas comerciales. También por la productividad de su banco pesquero y por la existencia de importantes yacimientos de hidrocarburos. Este último recurso ha despertado la ambición de las grandes transnacionales desde hace décadas. Este artículo viene a destacar el gran recorrido histórico que ha tenido la búsqueda de hidrocarburos en la zona, deteniéndose en el periodo 1940-1980

Compaction caused by soil tillage and seedbed preparation: effects on weed emergence in a barley crop

El objetivo principal de este trabajo fue evaluar los efectos de la compactación producida por la frecuencia de pases y el tipo de apero utilizado en la siembra del cereal, sobre la emergencia de las malas hierbas. Se utilizó un diseño en parcelas subdivididas con 4 repeticiones, con la labor primaria (fresa vs. cultivador) en parcelas principales y el pase de rulo (liso vs. pratenses) en subparcelas. Se tomaron datos de malas hierbas (densidad, biomasa) y de propiedades físicas del suelo (compactación, densidad aparente). Los resultados no han mostrado diferencias debidas a la labor primaria en ninguna de las variables analizadas, pero sí en función del tipo y frecuencia de pases de rulo, observándose menor densidad y biomasa de malas hierbas cuanto mayor era el número de pases de rulo, especialmente el liso, coincidiendo con los suelos más compactados. Sin embargo, parece existir un límite en el cual dejan de producirse efectos significativos debido a una sobrecompactación (e.g. doble pase de rulo y zona de rodada).The main objective of this work was to evaluate the effects of the compaction produced by the frequency of passes and the type of implement used in seedbed preparation, on weed emergence. A split-plot design with 4 replications was used, with the primary tillage (cultivator vs. rotary tiller) in main plots and rolling (flat roller vs. Cambridge roller) in subplots. Weeds data (density, biomass) and soil physical properties (compaction, bulk density) were assessed. The results showed no differences due to the primary tillage in any of the analyzed variables. However, the type and frequency of roller passes resulted in significant differences in weed abundance, with lower weed density and biomass when the number of roller passes was greater (especially flat roller), which coincided with the higher compaction. However, it seems to be a limit at which significant effects no longer occur due to an overcompaction (e.g. double roller pass and tractor wheel traffic)

Warm H2 in the Galactic center region

We present ISO observations of several H2 pure-rotational lines (from S(0) to S(5)) towards a sample of 16 molecular clouds distributed along the central ~ 500 pc of the Galaxy. We also present C18O and 13CO J=1->0 and J=2->1 observations of these sources made with the IRAM-30m telescope. With the CO data we derive H2 densities of 10e(3.5-4.0) cm-3 and H2 column densities of a few 10e22 cm-2. We have corrected the H2 data for ~ 30 magnitudes of visual extinction using a self-consistent method. In every source, we find that the H2 emission exhibits a large temperature gradient. The S(0) and S(1) lines trace temperatures (T) of ~150 K while the S(4) and S(5) lines indicate temperatures of ~ 600K. The warm H2 column density is typically ~1-2 x 10e22 cm-2, and is predominantly gas with T=150 K. This is the first direct estimate of the total column density of the warm molecular gas in the Galactic center region. These warm H2 column densities represent a fraction of ~ 30 % of the gas traced by the CO isotopes emission. The cooling by H2 in the warm component is comparable to that by CO. Comparing our H2 and CO data with available ammonia NH3 observations from literature one obtains relatively high NH3 abundances of a few 10e(-7) in both the warm and the cold gas. A single shock or Photo-Dissociation Region (PDR) cannot explain all the observed H2 lines. Alternatives for the heating mechanisms are discussed.Comment: 14 pages including figures, to be published in A&

Caracterización morfológica de hifas aéras y simulación del crecimiento de Fusarium solani bajo diferentes fuentes de carbono para su aplicación en la biofiltración de COVs hidrofóbicos

Publicado por la Academia Mexicana de Investigación y Docencia en Ingeniería Química A.C.This work presents the e ect of di erent carbon sources (glycerol, 1-hexanol and n-hexane)over the morphology of the aerial hyphae of the filamentous fungus Fusarium solani for its application in the biofiltration of volatile organic compounds (VOCs). A mathematical model was developed and further verified that combines microscopic and macroscopic parameters describing the mycelial fungal growth. Image analysis of microcultures and culture in agar dishes was performed to determine the morphological parameters. The results show that the hydrophobic and volatile carbon sources modified the morphology of Fusarium solani, this is associated with the better utilization of the volatile carbon source. The main morphology changes observed with glycerol and n-hexane, were the reduction in both the hyphal diameter (from 2.99 um to 2.01 um) and the average hyphal length (from 603.8 um to 280.1 um). These results indicate an increase in the transport area for the same amount of biomass as an adaptation response to increase the uptake of volatile hydrophobic substrates.Este trabajo presenta el efecto de diferentes fuentes de carbono (glicerol, 1-hexanol y n-hexano) sobre la morfología de las hifas aéreas del hongo filamentoso Fusarium solani para su aplicación en la biofiltración de compuestos orgánicos volátiles (COVs). Un modelo matemático que combina parámetros microscópicos y macroscópicos que describen el crecimiento del micelio del hongo fue desarrollado y verificado. Análisis de imágenes de los microcultivos y cultivos en placas de agar fue realizado para determinar los parámetros morfológicos. Los resultados muestran que las fuentes de carbono hidrofóbicas y volátiles modifican la morfología de Fusarium solani, esto está asociado con la mejor utilización de la fuente de carbono volátil. Los principales cambios morfológicos observados con glicerol y n-hexano, fueron la reducción en ambos diámetros de las hifas (desde 2.99 um a 2.01 um) y la longitud promedio de la hifa (desde 603.8 um a 280.1 um). Estos resultados indican un aumento en el área de transporte para la misma cantidad de biomasa como una respuesta de adaptación para aumentar la captación de los sustratos hidrofóbicos volátiles

Role of Klotho and AGE/RAGE-Wnt/β-catenin signalling pathway on the development of cardiac and renal fibrosis in diabetes

Fibrosis plays an important role in the pathogenesis of long-term diabetic complications and contributes to the development of cardiac and renal dysfunction. The aim of this experimental study, performed in a long-term rat model, which resembles type 1 diabetes mellitus, was to investigate the role of soluble Klotho (sKlotho), advanced glycation end products (AGEs)/receptor for AGEs (RAGE), fibrotic Wnt/β-catenin pathway, and pro-fibrotic pathways in kidney and heart. Diabetes was induced by streptozotocin. Glycaemia was maintained by insulin administration for 24 weeks. Serum and urine sKlotho, AGEs, soluble RAGE (sRAGE) and biochemical markers were studied. The levels of Klotho, RAGEs, ADAM10, markers of fibrosis (collagen deposition, fibronectin, TGF-β1, and Wnt/β-catenin pathway), hypertrophy of the kidney and/or heart were analysed. At the end of study, diabetic rats showed higher levels of urinary sKlotho, AGEs and sRAGE and lower serum sKlotho compared with controls without differences in the renal Klotho expression. A significant positive correlation was found between urinary sKlotho and AGEs and urinary albumin/creatinine ratio (uACR). Fibrosis and RAGE levels were significantly higher in the heart without differences in the kidney of diabetic rats compared to controls. The results also suggest the increase in sKlotho and sRAGE excretion may be due to polyuria in the diabetic rats