Autoignition of hydrogen/air mixtures by a thin catalytic wire

The autoignition of the catalytic reaction of hydrogen/air mixtures on thin palladium wires is analyzed in this paper. The reduced heterogeneous kinetics is modeled with a mechanism that includes the dissociative adsorption of both reactants, together with three surface reactions of the Langmuir-Hinshelwood type, and the desorption reaction of the adsorbed product, H2O(s). We show that for the description of the ignition conditions, this mechanism can be simplified to a single overall surface reaction involving the temperature and gas concentrations of the reactants at the surface of the wire. The resulting overall rate for the surface reaction has been tested with existing experimental results, after describing the transport of heat and reactants, by natural convection, in the gas phase for a wide range of Rayleigh numbers. The critical conditions for the catalytic ignition have been deduced using high activation energy asymptotics for the desorption kinetics of the most efficiently adsorbed reactant, H(s)

Kinematics of the ionized-to-neutral interfaces in Monoceros R2

Context. Monoceros R2 (Mon R2), at a distance of 830 pc, is the only ultra-compact H ii region (UC H ii) where its associated photon-dominated region (PDR) can be resolved with the Herschel Space Observatory. Aims. Our aim is to investigate observationally the kinematical patterns in the interface regions (i.e., the transition from atomic to molecular gas) associated with Mon R2. Methods. We used the HIFI instrument onboard Herschel to observe the line profiles of the reactive ions CH+, OH+ and H2O+ toward different positions in Mon R2. We derive the column density of these molecules and compare them with gas-phase chemistry models. Results. The reactive ion CH+ is detected both in emission (at central and red-shifted velocities) and in absorption (at blue-shifted velocities). OH+ is detected in absorption at both blue- and red-shifted velocities, with similar column densities. H2O+ is not detected at any of the positions, down to a rms of 40 mK toward the molecular peak. At this position, we find that the OH+ absorption originates in a mainly atomic medium, and therefore is associated with the most exposed layers of the PDR. These results are consistent with the predictions from photo-chemical models. The line profiles are consistent with the atomic gas being entrained in the ionized gas flow along the walls of the cavity of the H ii region. Based on this evidence, we are able to propose a new geometrical model for this region. Conclusions. The kinematical patterns of the OH+ and CH+ absorption indicate the existence of a layer of mainly atomic gas for which we have derived, for the first time, some physical parameters and its dynamics.Comment: 6 pages, 5 figures. Accepted for publication in A&

Deuteration around the ultracompact HII region Mon R2

The massive star-forming region Mon R2 hosts the closest ultra-compact HII region that can be spatially resolved with current single-dish telescopes. We used the IRAM-30m telescope to carry out an unbiased spectral survey toward two important positions (namely IF and MP2), in order to studying the chemistry of deuterated molecules toward Mon R2. We found a rich chemistry of deuterated species at both positions, with detections of C2D, DCN, DNC, DCO+, D2CO, HDCO, NH2D, and N2D+ and their corresponding hydrogenated species and isotopologs. Our high spectral resolution observations allowed us to resolve three velocity components: the component at 10 km/s is detected at both positions and seems associated with the layer most exposed to the UV radiation from IRS 1; the component at 12 km/s is found toward the IF position and seems related to the molecular gas; finally, a component at 8.5 km/s is only detected toward the MP2 position, most likely related to a low-UV irradiated PDR. We derived the column density of all the species, and determined the deuterium fractions (Dfrac). The values of Dfrac are around 0.01 for all the observed species, except for HCO+ and N2H+ which have values 10 times lower. The values found in Mon R2 are well explained with pseudo-time-dependent gas-phase model in which deuteration occurs mainly via ion-molecule reactions with H2D+, CH2D+ and C2HD+. Finally, the [H13CN]/[HN13C] ratio is very high (~11) for the 10 km/s component, which also agree with our model predictions for an age of ~0.01-0.1 Myr. The deuterium chemistry is a good tool for studying star-forming regions. The low-mass star-forming regions seem well characterized with Dfrac(N2H+) or Dfrac(HCO+), but it is required a complete chemical modeling to date massive star-forming regions, because the higher gas temperature together with the rapid evolution of massive protostars.Comment: 14 pages of manuscript, 17 pages of apendix, 7 figures in the main text, accepted for publication in A&

Linfadenectomía inguinal robot asistida (LIRA) para cáncer de pene

ResumenIntroducciónEl carcinoma de células escamosas es una entidad que ocupa el 2-5% de los tumores urogenitales, siendo por tanto poco frecuente, sin embargo en instituciones como la nuestra y por un alto volumen de pacientes y centro de referencia, se logra tener entre 5-7 casos por año. Dentro del tratamiento de estas lesiones se encuentra la linfadenectomía inguinal, la cual en la actualidad es realizada con mayor frecuencia con mínima invasión. Presentamos el caso de un paciente con carcinoma epidermoide de pene al que se le realizó linfadenectomía inguinal superficial y profunda con cirugía robot asistida.ObjetivoDescribir la técnica quirúrgica para linfadenectomía inguinal robot asistida en cáncer de pene.Presentación del casoHombre de 73 años con padecimiento con un año y 6 meses de evolución con aumento de volumen a nivel del glande; previa toma de biopsia se le realizó penectomía radical con uretrostomía perineal con resultado histopatológico de carcinoma epidermoide bien diferenciado verrucoso que infiltra el cuerpo esponjoso y la uretra (T3, N0, M0, G1); se realizó linfadenectomía inguinal robot asistida a las 4 semanas.ConclusionesLa linfadenectomía inguinal robot asistida es una técnica factible en centros en los que se cuente con dicha tecnología, logrando disminuir la morbilidad, el sangrado y la estancia hospitalaria, sin embargo tiene como desventaja el costo del procedimiento.AbstractIntroductionSquamous cell carcinoma is a rare tumor, making up from 2 to 5% of the urogenital tumors. However, because our hospital is a referral center that manages large numbers of patients, approximately 5-7 cases are seen per year. Inguinal lymph node dissection is one of the treatments for these lesions and is being performed more frequently as a minimally invasive procedure.ObjectiveOur aim was to describe the surgical technique for robotic-assisted inguinal lymphadenectomy in cancer of the penis. We present herein the case of a 73-year-old man with symptom progression of one year and 6 months and increased volume at the level of the glans penis. A biopsy was taken, after which he underwent radical penectomy with perineal urethrostomy. The histopathologic study reported well differentiated verrucous squamous cell carcinoma that invaded the corpus spongiosum and the urethra (T3N0M0G1). Four weeks later he underwent robotic-assisted inguinal lymphadenectomy of the superficial and deep lymph nodes.ConclusionsRobotic-assisted inguinal lymphadenectomy, aside from its high cost, is a feasible technique when carried out in specialized centers that reduces morbidity, blood loss, and hospital stay

Spatial distribution of small hydrocarbons in the neighborhood of the Ultra Compact HII region Monoceros R2

We study the chemistry of small hydrocarbons in the photon-dominated regions (PDRs) associated with the ultra-compact HII region Mon R2. Our goal is to determine the variations of the abundance of small hydrocarbons in a high-UV irradiated PDR and investigate their chemistry. We present an observational study of CH, CCH and c-C$_3$H$_2$ in Mon R2 combining data obtained with the IRAM 30m telescope and Herschel. We determine the column densities of these species, and compare their spatial distributions with that of polycyclic aromatic hydrocarbon (PAH). We compare the observational results with different chemical models to explore the relative importance of gas-phase, grain-surface and time-dependent chemistry in these environments. The emission of the small hydrocarbons show different patterns. The CCH emission is extended while CH and c-C$_3$H$_2$ are concentrated towards the more illuminated layers of the PDR. The ratio of the column densities of c-C$_3$H$_2$ and CCH shows spatial variations up to a factor of a few, increasing from $N(c-C$_3$H$_2$)/N(CCH)\approx0.004$ in the envelope to a maximum of $\sim0.015-0.029$ towards the 8$\mu$m emission peak. Comparing these results with other galactic PDRs, we find that the abundance of CCH is quite constant over a wide range of G$_0$, whereas the abundance of c-C$_3$H$_2$ is higher in low-UV PDRs. In Mon R2, the gas-phase steady-state chemistry can account relatively well for the abundances of CH and CCH in the most exposed layers of the PDR, but falls short by a factor of 10 to reproduce c-C$_3$H$_2$. In the molecular envelope, time-dependent effects and grain surface chemistry play a dominant role in determining the hydrocarbons abundances. Our study shows that CCH and c-C$_3$H$_2$ present a complex chemistry in which UV photons, grain-surface chemistry and time dependent effects contribute to determine their abundances.Comment: 18 pages, 11 figures, 7 tables. Proposed for acceptance in A&A. Abstract abridge

Symmetry breaking perturbations and strange attractors

The asymmetrically forced, damped Duffing oscillator is introduced as a prototype model for analyzing the homoclinic tangle of symmetric dissipative systems with \textit{symmetry breaking} disturbances. Even a slight fixed asymmetry in the perturbation may cause a substantial change in the asymptotic behavior of the system, e.g. transitions from two sided to one sided strange attractors as the other parameters are varied. Moreover, slight asymmetries may cause substantial asymmetries in the relative size of the basins of attraction of the unforced nearly symmetric attracting regions. These changes seems to be associated with homoclinic bifurcations. Numerical evidence indicates that \textit{strange attractors} appear near curves corresponding to specific secondary homoclinic bifurcations. These curves are found using analytical perturbational tools

Combined therapy in diabetic macular edema

Purpose: To determine the effectiveness of three different combinations for the ‘‘loading phase’’ in the treatment of diabetic macular edema (DME), using bevacizumab (BVZ), triamcinolone (TCL) and subthreshold macular photocoagulation (SMPC). Methods: Experimental, longitudinal, prospective, comparative and blind. Patients were randomly assigned to three treatment branches: Group 1: BVZ + SMPC (12 eyes), Group 2: SMPC + BVZ + TCL (7 eyes), Group 3: BVZ + TCL (11 eyes). Treatment with BVZ and TCL was given every 4 weeks for 3 months, SMPC was applied once at the beginning of treatment. Initial and final measurements of best corrected visual acuity (BCVA), central macular thickness (CMT) and intraocular pressure (IOP) were tested. Results: The improvement in BCVA and the reduction in CMT was statistically superior in group of BVZ + SMPCwhen compared to the other groups. There were no differences in IOP. Conclusions: Combined therapies in the ‘‘loading phase’’are a good option when treating DME. Although the group with BVZ + SMPC obtained the best results, further studies with longer followup and a higher number of participants to establish this combined therapy as the first treatment option are required

Far-infrared observations of a massive cluster forming in the Monoceros R2 filament hub

We present far-infrared observations of Monoceros R2 (a giant molecular cloud at approximately 830 pc distance, containing several sites of active star formation), as observed at 70 μm, 160 μm, 250 μm, 350 μm, and 500 μm by the Photodetector Array Camera and Spectrometer (PACS) and Spectral and Photometric Imaging Receiver (SPIRE) instruments on the Herschel Space Observatory as part of the Herschel imaging survey of OB young stellar objects (HOBYS) Key programme. The Herschel data are complemented by SCUBA-2 data in the submillimetre range, and WISE and Spitzer data in the mid-infrared. In addition, C18O data from the IRAM 30-m Telescope are presented, and used for kinematic information. Sources were extracted from the maps with getsources, and from the fluxes measured, spectral energy distributions were constructed, allowing measurements of source mass and dust temperature. Of 177 Herschel sources robustly detected in the region (a detection with high signal-to-noise and low axis ratio at multiple wavelengths), including protostars and starless cores, 29 are found in a filamentary hub at the centre of the region (a little over 1% of the observed area). These objects are on average smaller, more massive, and more luminous than those in the surrounding regions (which together suggest that they are at a later stage of evolution), a result that cannot be explained entirely by selection effects. These results suggest a picture in which the hub may have begun star formation at a point significantly earlier than the outer regions, possibly forming as a result of feedback from earlier star formation. Furthermore, the hub may be sustaining its star formation by accreting material from the surrounding filaments

How does ethical leadership trickle down? Test of an integrative dual-process model

Although the trickle-down effect of ethical leadership has been documented in the literature, its underlying mechanism still remains largely unclear. To address this gap, we develop a cross-level dual-process model to explain how the effect occurs. Drawing on social learning theory, we hypothesize that the ethical leadership of high-level managers could cascade to middle-level supervisors via its impact on middle-level supervisors’ two ethical expectations. Using a sample of 69 middle-level supervisors and 381 subordinates across 69 sub-branches from a large banking firm in China, we found that middle-level supervisors’ ethical efficacy expectation and unethical behavior–punishment expectation (as one form of ethical outcome expectations) accounted for the trickle-down effect. The explanatory role of middle-level supervisors’ ethical behavior–reward expectation (as the other form of ethical outcome expectations), however, was not supported. The theoretical and practical implications are discussed