Caracterización de la respuesta electroantenográfica de Cerambyx welensii Küster y Prinobius germari Dejean (Coleoptera: Cerambycidae)

Xylophagous cerambycids of Cerambyx and Prinobius genus can play an important role in «oak decline» in Spain. New trends in the integrated pest management are dealing with control strategies based on the relation between olfactory perception of semiochemicals and insect behaviour. Electroantennography of olfactory stimuli enables to interpret the significance of the olfactory stimulation in host selection, an unknown aspect within many xylophagous insects. Cerambyx welensii and Prinobius germari (Coleoptera, Cerambycidae), have responded in EAG tests to two different compounds: a green-leaves volatile (E)-2-hexenal and turpentine; C. welensii also responded to acetic acid. Strong stimulatory conditions (20 μl of stimulating blend at 1:1 v/v doses) favour high EAG responses, without causing antennal saturation. Under these stimulatory conditions, and using complete insects, we have obtained stable EAG responses during, at least, five hours. Results show a good aptitude of these species for deeper electrophysiological experiments (such chromatography linked to electroantennography), in search of the olfactory cues involved in host location.Los cerambícidos xilófagos de los géneros Cerambyx y Prinobius pueden desempeñar un papel relevante en el decaimiento del género Quercus en España. Las nuevas tendencias en el control integrado de plagas apuestan por medidas basadas en el comportamiento de los insectos ante la percepción de compuestos semioquímicos. La electroantenografía permite interpretar la relevancia de la estimulación olfativa en la selección de hospedantes, aspecto desconocido para muchos insectos xilófagos. Cerambyx welensii y Prinobius germari han respondido electroantenográficamente frente a dos tipos de sustancias: un volátil de hojas verdes –(E)-2-hexenal- y la esencia de trementina; C. welensii respondió además frente al ácido acético. Condiciones de estimulación fuertes (20 μl de mezcla estimulante a concentración 1:1 en volumen) favorecen la obtención de respuestas de EAG elevadas, sin saturar la antena. Bajo estas condiciones de estimulación, y empleando insectos completos, se ha encontrado que una preparación para estudio de EAG puede durar cinco horas al menos. Los resultados manifiestan una buena aptitud de dichas especies para la realización de estudios electrofisiológicos más amplios (como la cromatografía acoplada a la electroantenografía), que permitan interpretar la mediación de la estimulación olfativa en la localización de sus principales hospedantes

Variabilidad intraespecífica de la respuesta electroantenográfica en Cerambyx welensii Küster (Coleoptera, Cerambycidae). Influencia de factores anatómicos, fisiológicos y experimentales

Intraspecific variability of EAG responses in Cerambyx welensii has been studied.We have not found significant differences of EAG responses neither between sexes nor types of solvent, paraffin oil and hexane, but there was a highly significant variability of responses between individuals (0,92 mV +/- 0,6. Mean +/- DT) to (E)-2-hexenal (50% v/v). More than 68% of individual variability can be explained by the combination of the previous aptitude of insects, its physiological state (vitality at the moment of study) and the capillary's diameter in the reference electrode. Anatomical features of the individuals had not influence in the response. In order to avoid or minimize the effect caused for this variability, it is advisable to carry out EAG tests with insects obtained under controlled conditions. In other case, the EAG responses must be standardized using a standard stimulus, as well as to homogenize the tip diameter of the reference electrode.En este trabajo se estudia la variabilidad intraespecífica de la respuesta electroantenográfica de Cerambyx welensii. No se han encontrado diferencias de respuestas entre sexos, ni entre el tipo de solvente empleado, hexano o aceite de parafina; pero sí se encontró variabilidad entre individuos (0,92 mV +/- 0,6. Media +/- DT) frente al (E)-2-hexenal (50% v/v). Más del 68% de esta variabilidad pudo ser explicada considerando tres factores: la aptitud previa de los insectos, su estado fisiológico (vigor en el momento del estudio) y el diámetro en punta fina del capilar del electrodo de referencia. Las características anatómicas de los individuos no influyeron sobre su respuesta electroantenográfica. La variabilidad de respuesta intraespecífica encontrada en C. welensii puede distorsionar la caracterización del comportamiento olfativo de esta especie, por lo que es deseable realizar las pruebas electroantenográficas a partir de insectos obtenidos en condiciones controladas o bien estandarizar las respuestas a partir de un estímulo estándar, además de normalizar el diámetro del capilar del electrodo de referencia

Lucky Imaging Adaptive Optics of the brown dwarf binary GJ569Bab

The potential of combining Adaptive Optics (AO) and Lucky Imaging (LI) to achieve high precision astrometry and differential photometry in the optical is investigated by conducting observations of the close 0\farcs1 brown dwarf binary GJ569Bab. We took 50000 $I$-band images with our LI instrument FastCam attached to NAOMI, the 4.2-m William Herschel Telescope (WHT) AO facility. In order to extract the most of the astrometry and photometry of the GJ569Bab system we have resorted to a PSF fitting technique using the primary star GJ569A as a suitable PSF reference which exhibits an $I$-band magnitude of $7.78\pm0.03$. The AO+LI observations at WHT were able to resolve the binary system GJ569Bab located at 4\farcs 92 \pm 0\farcs05 from GJ569A. We measure a separation of $98.4 \pm 1.1$ mas and $I$-band magnitudes of $13.86 \pm 0.03$ and $14.48 \pm 0.03$ and $I-J$ colors of 2.72$\pm$0.08 and 2.83$\pm$0.08 for the Ba and Bb components, respectively. Our study rules out the presence of any other companion to GJ569A down to magnitude I$\sim$ 17 at distances larger than 1\arcsec. The $I-J$ colors measured are consistent with M8.5-M9 spectral types for the Ba and Bb components. The available dynamical, photometric and spectroscopic data are consistent with a binary system with Ba being slightly (10-20%) more massive than Bb. We obtain new orbital parameters which are in good agreement with those in the literature.Comment: 13 pages, 9 figures, 7 tables, in press in MNRA

Interfaz Gráfica Computacional para Destilación Multicomponente utilizando Métodos Cortos

In this work, we developed a graphical interface that determines by steady-state simulation the number of plates required for multicomponent distillation process and the composition of distillate and bottoms flow of a distillation tower using short-cut methods. The graphical user interface was built in the programming language Python 2.5, allows to present the input and output data for the case of distillation columns operating in steady state. The results of using the graphical interface shows a simple way to make preliminary designs of distillation towers and its potential as support material for the study and understanding of basic concepts in multicomponent distillation. In a later work it will can display the dynamic model performance through scheduled disturbances in operating conditions.Keywords: multicomponent distillation, shorcut methods, graphical user interface, Phyton 2.5.DOI: http://dx.doi.org/10.5377/nexo.v24i2.660En este trabajo, se elaboró una interfaz gráfica que determina por medio de simulación en estado estacionario el número de platos necesarios en el proceso de destilación multicomponente, así como la composición en el flujo de destilado y fondos de una torre de destilación utilizando métodos cortos. La interfaz gráfica de usuario, se construyó en el lenguaje de programación Python 2.5, permite presentar los datos de entrada y salida para el caso de columnas de destilación operando en régimen permanente. Los resultados del uso de la interfaz gráfica muestran una forma simple de realizar diseños preliminares de torres de destilación y su potencialidad como material de apoyo para el estudio y comprensión de conceptos básicos en destilación multicomponente. En un trabajo posterior se podrá visualizar el desempeño del modelo dinámico a través de perturbaciones programadas en las condiciones de operación.Palabras claves: destilación multicomponente, métodos cortos, interfaz gráfica de usuario, Phyton 2.5.DOI: http://dx.doi.org/10.5377/nexo.v24i2.66

New constraints on the membership of the T dwarf S Ori 70 in the sigma Orionis cluster

(Abridged) The nature of S Ori 70, a faint mid-T type object found towards the direction of the young sigma Orionis cluster, is still under debate. We intend to disentangle whether it is a field brown dwarf or a 3-Myr old planetary-mass member of the cluster. We report on near-infrared JHK_s and mid-infrared [3.6] and [4.5] IRAC/Spitzer photometry recently obtained for S Ori 70. The new near-infrared images (taken 3.82 yr after the discovery data) have allowed us to derive a very small proper motion (11.0 +/- 5.9 mas/yr) for this object, which is consistent with the proper motion of the cluster within 1.5 sigma the astrometric uncertainty. The colors (H-K_s), (J-K_s) and K_s-[3.6] appear discrepant when compared to T4-T7 dwarfs in the field. This behavior could be ascribed to a low-gravity atmosphere or alternatively to an atmosphere with a metallicity significantly different than solar. Taking into account the small proper motion of S Ori 70 and its new near- and mid-infrared colors, a low-gravity atmosphere remains as the most likely explanation to account for our observations. This supports S Ori 70's membership in sigma Orionis, with an estimated mass in the interval 2-7 Mjup, in agreement with our previous derivation.Comment: Accepted for publication in A&

Detection of He I λ10830\lambda10830 \AA{} absorption on HD 189733 b with CARMENES high-resolution transmission spectroscopy

We present three transit observations of HD 189733 b obtained with the high-resolution spectrograph CARMENES at Calar Alto. A strong absorption signal is detected in the near-infrared He I triplet at 10830 \AA{} in all three transits. During mid-transit, the mean absorption level is $0.88\pm0.04$ % measured in a $\pm$10 km s$^{-1}$ range at a net blueshift of $-3.5\pm0.4$ km s$^{-1}$ (10829.84--10830.57 \AA{}). The absorption signal exhibits radial velocities of $+6.5\pm3.1$ km s$^{-1}$ and $-12.6\pm1.0$ km s$^{-1}$ during ingress and egress, respectively; measured in the planetary rest frame. We show that stellar activity related pseudo-signals interfere with the planetary atmospheric absorption signal. They could contribute as much as 80% of the observed signal and might also affect the radial velocity signature, but pseudo-signals are very unlikely to explain the entire signal. The observed line ratio between the two unresolved and the third line of the He I triplet is $2.8\pm0.2$, which strongly deviates from the value expected for an optically thin atmospheres. When interpreted in terms of absorption in the planetary atmosphere, this favors a compact helium atmosphere with an extent of only 0.2 planetary radii and a substantial column density on the order of $4\times 10^{12}$ cm$^{-2}$. The observed radial velocities can be understood either in terms of atmospheric circulation with equatorial superrotation or as a sign of an asymmetric atmospheric component of evaporating material. We detect no clear signature of ongoing evaporation, like pre- or post-transit absorption, which could indicate material beyond the planetary Roche lobe, or radial velocities in excess of the escape velocity. These findings do not contradict planetary evaporation, but only show that the detected helium absorption in HD 189733 b does not trace the atmospheric layers that show pronounced escape signatures.Comment: 13 pages, 12 figures, accepted for publication in A&

Candidate free-floating super-Jupiters in the young sigma Orionis open cluster

Free-floating substellar candidates with estimated theoretical masses of as low as ~5 Jupiter masses have been found in the ~3 Myr old sigma Orionis open cluster. As the overlap with the planetary mass domain increases, the question of how these objects form becomes important. The determination of their number density and whether a mass cut-off limit exists is crucial to understanding their formation. We propose to search for objects of yet lower masses in the cluster and determine the shape of the mass function at low mass. Using new- and (re-analysed) published IZJHKs[3.6]-[8.0]-band data of an area of 840 arcmin2, we performed a search for LT-type cluster member candidates in the magnitude range J=19.5-21.5 mag, based on their expected magnitudes and colours. Besides recovering the T type object S Ori 70 and two other known objects, we find three new cluster member candidates, S Ori 72-74, with J=21 mag and within 12 arcmin of the cluster centre. They have theoretical masses of 4 (-2,+3) M_Jup and are among the least massive free-floating objects detected by direct imaging outside the Solar System. The photometry in archival Spitzer [3.6]-[5.8]-band images infers that S Ori 72 is an L/T transition candidate and S Ori 73 a T-type candidate, following the expected cluster sequence in the mid-infrared. Finally, the L-type candidate S Ori 74 with lower quality photometry is located at 11.8 arcsec (~4250 AU) of a stellar member of sigma Orionis and could be a companion. After contaminant correction in the area complete to J=21.1 mag, we estimate that there remain between zero and two cluster members in the mass interval 6-4 M_Jup. Our result suggests a possible turnover in the substellar mass spectrum below ~6 Jupiter masses, which could be investigated further by wider and deeper photometric surveys.Comment: 15 pages, 13 figures, 5 tables, and appendix containing 5 figures; accepted for publication in AA; v2: 2 minor corrections, in abstract and sect. 2.

Discriminating between hazy and clear hot-Jupiter atmospheres with CARMENES

Context: Relatively large radii of some hot Jupiters observed in the ultraviolet (UV) and blue-optical are generally interpreted to be due to Rayleigh scattering by high-altitude haze particles. However, the haze composition and its production mechanisms are not fully understood, and observational information is still limited. Aims: We aim to study the presence of hazes in the atmospheres of HD 209458 b and HD 189733 b with high spectral resolution spectra by analysing the strength of water vapour cross-correlation signals across the red optical and near-infrared wavelength ranges. Methods: A total of seven transits of the two planets were observed with the CARMENES spectrograph at the 3.5 m Calar Alto telescope. Their Doppler-shifted signals were disentangled from the telluric and stellar contributions using the detrending algorithm SYSREM. The residual spectra were subsequently cross-correlated with water vapour templates at 0.70-0.96 $\mu$m to measure the strength of the water vapour absorption bands. Results: The optical water vapour bands were detected at $5.2 \sigma$ in HD 209458 b in one transit, whereas no evidence of them was found in four transits of HD 189733 b. Therefore, the relative strength of the optical water bands compared to those in the near-infrared were found to be larger in HD 209458 b than in HD 189733 b. Conclusions: We interpret the non-detection of optical water bands in the transmission spectra of HD 189733 b, compared to the detection in HD 209458 b, to be due to the presence of high-altitude hazes in the former planet, which are largely absent in the latter. This is consistent with previous measurements with the Hubble Space Telescope. We show that currently available CARMENES observations of hot Jupiters can be used to investigate the presence of haze extinction in their atmospheres.Comment: 13 pages; accepted for publication in A&

Desafíos y tendencias del México actual

Conjunto de once ensayos cuyo propósito es suscitar la reflexión sobre las tendencias más importantes que marcan el inicio del siglo XXI en México y Jalisco, sin obviar las direcciones que a escala mundial toman la vida social, política y económica.ITESO, A.C