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

Crack-Depth Prediction in Steel Based on Cooling Rate

One criterion for the evaluation of surface cracks in steel welds is to analyze the depth of the crack, because it is an effective indicator of its potential risk. This paper proposes a new methodology to obtain an accurate crack-depth prediction model based on the combination of infrared thermography and the 3D reconstruction procedure. In order to do this, a study of the cooling rate of the steel is implemented through active infrared thermography, allowing the study of the differential thermal behavior of the steel in the fissured zone with respect to the nonfissured zone. These cooling rate data are correlated with the real geometry of the crack, which is obtained with the 3D reconstruction of the welds through a macrophotogrammetric procedure. In this way, it is possible to analyze the correlation between cooling rate and depth through the different zones of the crack. The results of the study allow the establishment of an accurate predictive depth model which enables the study of the depth of the crack using only the cooling rate data. In this way, the remote measure of the depth of the surface steel crack based on thermography is possible

Effect of welding sequence in angular distortion on butt joint GMAW process

Over time, the industrial use of the welding process has grown in significance and is now one of the primary methods for joining metallic parts. During the welding process, metallurgical and structural modifications occur close to the welded joint. The thermal stresses and geometric distortions are undesirable, and they are a challenge to accurately forecast. Laboratory tests were conducted utilizing the GMAW method on S235JR steel as the base material with the goal of examining the impact of the welding sequence on angular distortion in butt joints when comparing three different welding sequences. Equipment that can determine coordinates in the operational space with metrological accuracy was used to measure distortions. As a result of metrological and statistical analyses, it was found that the sequence factor is shown to substantially influence the final distortions and that the symmetrical method results in less distortions followed by a one-step method.Financial support was provided by Portugal’s national funding FCT/MCTES (PIDDAC) to Centro de Investigação de Montanha (CIMO) (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LA/P/0007/2020).info:eu-repo/semantics/publishedVersio

Técnicas SIG aplicadas al estudio del relieve de los Montes de León (NO de la Península Ibérica)

En este trabajo se presenta un método basado en el análisis de modelos digitales de elevación (MDE) a través de SIG, encaminado a realizar una cartografía preliminar de antiguas superficies de aplanamiento en los relieves que bordean la cuenca del Bierzo (oeste de la provincia de León, noroeste de la Península Ibérica). El área de estudio es un complejo sistema escalonado de niveles de aplanamiento elaborados sobre el basamento del Macizo Ibérico, constituyente de los relieves montañosos de la zona, deformado por la Orogenia Alpina durante el Cenozoico, en donde las superficies se encuentran elevadas, basculadas, fragmentadas y muy degradadas. Partiendo del MDE con paso de malla de 25 m del PNOA se realizó una caracterización general de la zona de estudio mediante la obtención de mapas derivados: pendientes, orientaciones de pendiente y sombreado, así como de la red de drenaje. Empleando la extensión EZ Profile para ArcGIS 9.3 se generaron 213 perfiles topográficos, sobre los principales cordales e interfluvios, con los que se localizaron y correlacionaron los elementos culminantes (indicios y restos de superficies de aplanamiento) presentes en toda la zona de estudio, lo que permitió reconstruir el relieve previo al desmantelamiento por parte de la red de drenaje. Una vez delimitadas las superficies de aplanamiento se procedió a su caracterización, agrupación y jerarquización, mediante el estudio de superficies de tendencia, el análisis de la red de drenaje y la relación con la actividad tectónica. Se realizó una reconstrucción teórica de cada uno de los aplanamientos a través de la interpolación de los puntos pertenecientes al antiguo relieve, generando así una superficie de tendencia de primer orden, de donde se obtuvo la orientación y pendiente de cada una de ellas. A su vez, se buscaron anomalías en los cauces de los ríos que atraviesan los aplanamientos, que pudieran indicar actividad tectónica reciente. Asimismo, se llevó a cabo un estudio de las cuencas de drenaje, sobre las que se realizaron cálculos de hipsometría y de asimetría (Factor de Asimetría). Por último, se calculó la incisión del drenaje sobre las superficies de aplanamiento cartografiadas. Como resultado se obtuvieron veinte superficies clasificadas en ocho niveles, desde los 1000m a los 2100m, en donde se observa cómo los distintos elementos de un mismo nivel se encuentran en extremos opuestos de la zona de estudio, ubicados en forma de orla perdiendo altura hacia la cuenca del Bierzo.Trabajo financiado por el proyecto de la Junta de Castilla y León LE311A12-2 y por el proyecto Consolider Ingenio 2006 CSD-2006, TopoIberia Geociencias en Iberia

3 mm spectral line survey of two lines of sight toward two typical cloud complexes in the Galactic Center

We present the results of two Mopra 3-mm spectral line surveys of the Lines of Sight (LOS) toward the Galactic Center (GC) molecular complexes Sgr B2 (LOS+0.693) and Sgr A (LOS-0.11). The spectra covered the frequency ranges of ~77-93 GHz and ~105-113 GHz. We have detected 38 molecular species and 25 isotopologues. The isotopic ratios derived from column density ratios are consistent with the canonical values, indicating that chemical isotopic fractionation and/or selective photodissociation can be considered negligible (<10%) for the GC physical conditions. The derived abundance and rotational temperatures are very similar for both LOSs, indicating very similar chemical and excitation conditions for the molecular gas in the GC. The excitation conditions are also very similar to those found for the nucleus of the starburst galaxy NGC 253. We report for the first time the detection of HCO and HOC+ emission in LOS+0.693. Our comparison of the abundance ratios between CS, HCO, HOC+ and HCO+ found in the two LOSs with those in typical Galactic photodissociation regions (PDRs) and starbursts galaxies does not show any clear trend to distinguish between UV and X-ray induced chemistries. We propose that the CS/HOC+ ratio could be used as a tracer of the PDR components in the molecular clouds in the nuclei of galaxies

Interaction Effects on the Magneto-optical Response of Magnetoplasmonic Dimers

The effect that dipole-dipole interactions have on the magneto-optical (MO) properties of magnetoplasmonic dimers is theoretically studied. The specific plasmonic versus magnetoplasmonic nature of the dimer's metallic components and their specific location within the dimer plays a crucial role on the determination of these properties. We find that it is possible to generate an induced MO activity in a purely plasmonic component, even larger than that of the MO one, therefore dominating the overall MO spectral dependence of the system. Adequate stacking of these components may allow obtaining, for specific spectral regions, larger MO activities in systems with reduced amount of MO metal and therefore with lower optical losses. Theoretical results are contrasted and confirmed with experiments for selected structures

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&

Sensitivity enhancement by increasing the nonlinear crystal length in second-order autocorrelators for ultrashort laser pulses measurement

A theoretical model for interferometric autocorrelation with long nonlinear crystal (input depleted) has been developed and applied to the measurement of the duration of ultrashort pulses. The phase-matching condition is assumed throughout pulse spectrum. The interferometric autocorrelation trace of a mode-locked fibre laser (20 nJ energy, 100 kW peak power, centred at 1595 nm) has been measured by employing a fibre interferometer to avoid misalignment effects and a BBO nonlinear crystal as long as 2 mm, in order to generate higher second-harmonic power. BBO crystal was used because it can keep the phase-matching condition throughout a wide spectrum around 1600 nm. By fitting the experimental measurements and computing according to the theoretical model exposed, it has been demonstrated that the autocorrelator sensitivity is clearly enhanced by increasing the nonlinear crystal length. A temporal duration of 0.18 ps has been obtained by fitting theoretical and experimental values

Changes produced in the intramuscular tissue via dry needling measured with magnetic resonance imaging

Abstract Introduction Myofascial trigger points are a common cause of pain and clinically observed local muscle sensitivity. The improvement associated with the muscle relaxation effect (reduction of muscle rigidity) produced by dry needling (DN) is still not well known. Thus, it is thought that the regeneration of the tissue that has been destructed by dry needling via the inflammatory process occurs with the return to normal muscle contractility. Aims The aim of this study was to identify whether the local inflammatory effect is immediately induced by DN, using magnetic resonance imaging (MRI). Material and Methods 18 asymptomatic patients were evaluated, with latent trigger points in the medial gastrocnemius (MG). We used an intergroup research design to study differences in MRI signal in the medial gastrocnemius, before and after performing DN. The MG which presented the most pain in response to pressure, was used as the experimental or intervention group, whereas the contralateral MG was used as the control group. MRI was used with signal intensity (STIR), to identify signal changes due to local inflammation. An ANOVA test was performed to analyze the influence of DN in the STIR variable and a Student's t-test for dependent samples was used to compare the perception of pain after DN. Results The STIR increased by 128.97% after DN in the experimental group. The effect of the interaction showed significant differences (F (1.34) = 235, p = 0.0001, r = 0.93). The Bonferroni post hoc tests showed significant differences [differences in means and 95% confidence interval (95%CI) = 198 (172 - 224)] signal intensity (F (1.34) = 236, p = 0.001; r = 0.93; d = 5.03). Furthermore, a significant group was found (control vs. experimental group) after controlling for the effects of the intervention (F (1.33) = 9.95, p = 0.003, r = 0.48, d = 1.10). Regarding the perception of pain in response to pressure, a significant reduction was found between the pre and post intervention measurements (t (17) = 12.40, p = 0.001, r = 0.65, d = 1.71). The Pearson's correlation coefficient did not display any correlation among any variable. Conclusion Intramuscular edema appears immediately after (1h) the application of DN, which indicates an inflammatory process with an unexpected reduction in pain perception. Our results are in line with other findings in mice which display signs of an inflammatory response after DN. A limitation of this study was the lack of further MRI measurements to detect when the edema resolved