The electron-phonon coupling strength at metal surfaces directly determined from the Helium atom scattering Debye-Waller factor

A new quantum-theoretical derivation of the elastic and inelastic scattering probability of He atoms from a metal surface, where the energy and momentum exchange with the phonon gas can only occur through the mediation of the surface free-electron density, shows that the Debye-Waller exponent is directly proportional to the electron-phonon mass coupling constant $\lambda$. The comparison between the values of $\lambda$ extracted from existing data on the Debye-Waller factor for various metal surfaces and the $\lambda$ values known from literature indicates a substantial agreement, which opens the possibility of directly extracting the electron-phonon coupling strength in quasi-2D conducting systems from the temperature or incident energy dependence of the elastic Helium atom scattering intensities.Comment: 14 pages, 2 figures, 1 tabl

Ovary Development and Maturation in Nezara viridula (L.) (Hemiptera: Pentatomidae)

Ovary development and maturation of Nezara viridula (L.) were evaluated by examining ovariole morphology and the alterations in the biochemical (protein synthesis related to reproduction) composition of the hemolymph. Quantitative and qualitative protein analyses were performed and ovary structural alterations for the pre-reproductive and reproductive stages were recorded. Total concentration of proteins in female hemolymph gradually increased until the end of the pre-mating stage, remaining unaltered thereafter. Proteins linked to reproduction (vitellogenins) appeared in the hemolymph 10 days after adult emergence and indicated the end of the pre-mating stage. After mating, total protein concentration in the hemolymph was lower compared to virgin females; vitellogenin levels were similar during most of the observation period. Oocyte development and maturation were gradual and age dependent. Ten-day-old females had chorionated oocytes ready for fertilization. Mating did not stimulate oocyte development in N. viridula, but the lack of mating activity appeared to have stimulated oocyte resorption in 17-day-old females.Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq

The impact of digitalisation on remittances. Evidence from El Salvador

This paper carries out a microeconomic analysis of the determinants of remittances from a receiving perspective in El Salvador. Specifically, using data from the ‘Encuesta de Hogares de Propósitos Múltiples of 2016’ (2016 Multi-purpose Household Survey -EHPM16), the characteristics of households that affect the reception of remittances in El Salvador in 2016 were analysed, focusing on the level of digitalisation in households. Determinants of remittances are not everlasting and are affected by social and economic changes. In this sense, the effect on remittances caused by an increase in the widespread use of Information and Communication Technologies (ICT) is not an exception. Based on a two steps selection model, the results point out that the household's level of digitalisation significantly increases the probability of receiving remittances, not their amount

Modelo numérico de cavitación para geometrías sencillas utilizando FLUENT V6.1

Cavitation is a phenomenon that can be present in several agro-forestry applications such as irrigation pressure-reducing valves, sprinkler orifices or even in the flow through xylem vessels inside plants. In the present research, numerical predictions of cavitation in a series of orifices, nozzles and venturis were compared to experimental measurements to show the possibilities and performances of the new cavitation model in the commercial Computational Fluid Dynamics (CFD) code FLUENT V6.1. A flashing study is also presented for the nozzle case. Model predictions for the orifice cases accurately capture cavitation inception and its influence on the orifice discharge coefficient. However, when an unsteady flow is modeled, the cavitation phenomenon is not simulated properly and leads to a steady situation. In general, the new cavitation model in FLUENT V6.1 provides very reliable simulation for easy geometries when steady flow is assumed.Los procesos de cavitación tienen relevancia en diferentes aspectos del área agroforestal, como en válvulas reductoras de presión para riego, chorros en aspersores e incluso en el flujo de savia en el xilema de las plantas. En este trabajo se ha validado el nuevo modelo de cavitación incluido en el programa comercial de mecánica de fluidos computacional FLUENT V6.1 en varios orificios, estrechamientos y venturis, comparando los resultados experimentales con los obtenidos por el modelo. También se presenta un estudio del fenómeno "flashing" producido en el estrechamiento. Las predicciones del modelo en el caso de los orificios muestran una buena estimación del momento de inicio de la cavitación así como de su desarrollo, estimado con el coeficiente de descarga del orificio. Sin embargo, cuando se trata de modelar el flujo en estado no estacionario, el proceso de cavitación no es simulado correctamente conduciendo a una situación estacionaria. De todo ello podemos concluir que el nuevo modelo de cavitación simula adecuadamente la cavitación en el flujo a través de geometrías sencillas, como los orificios y estrechamientos, en estado estacionario

Circular Bedforms Due to Pit Foraging of Greater Flamingo Phoenicopterus roseus in a Back-barrier Intertidal Habitat

The Greater Flamingo Phoenicopterus roseus is known as an ecosystem engineer, rearranging sediment in peculiar bedforms as a consequence of its filter-feeding behaviour. In recent decades, the populations of the Greater Flamingo have notably increased, and now the species is one of the most abundant waterbirds in Mediterranean wetlands. Owing to its range expansion, it inhabits and exploits new and suitable foraging sites detectable by foraging structures left on the sediment. There are few images of the foraging morphologies in the literature, possibly due to their ephemeral nature and difficulty in detecting them. In this manuscript, we present a very detailed UAV (Unmanned Aerial Vehicle) image of an aggregate of pit foraging structures of Greater Flamingo discovered on a back-barrier washover fan in the Marano and Grado Lagoon (Northern Adriatic, Italy)

Gold-catalyzed 1, 3-Thiazine formation and uncommon tautomer isolation

This work represents the first example of a gold-catalyzed formation of 1, 3-thiazine/1, 3-thiazinane by means of a catalytic approach and further uncommon isolation of the two tautomers. The developed protocol gives rise to a broad scope of 1, 3-thiazine derivatives with excellent yields in short reaction times. Interestingly, different isomers could be obtained depending on the state of the compound, and in the crystal state the 1, 3-thiazinane isomer is obtained, while in solution the 1, 3-thiazine is the unique isomer. This work represents an interesting approach for the synthesis of potential biologically relevant molecules and a crucial precedent in tautomerism isolation and characterization. © 2022 American Chemical Society. All rights reserved

Multiple Sources toward the High-mass Young Star S140 IRS1

S140 IRS1 is a remarkable source where the radio source at the center of the main bipolar molecular outflow in the region is elongated perpendicular to the axis of the outflow, an orientation opposite to that expected if the radio source is a thermal jet exciting the outflow. We present results of 1.3 cm continuum and H2O maser emission observations made with the VLA in its A configuration toward this region. In addition, we also present results of continuum observations at 7 mm and re-analyse observations at 2, 3.5 and 6 cm (previously published). IRS 1A is detected at all wavelengths, showing an elongated structure. Three water maser spots are detected along the major axis of the radio source IRS 1A. We have also detected a new continuum source at 3.5 cm (IRS 1C) located ~0.6'' northeast of IRS 1A. The presence of these two YSOs (IRS 1A and 1C) could explain the existence of the two bipolar molecular outflows observed in the region. In addition, we have also detected three continuum clumps (IRS 1B, 1D and 1E) located along the major axis of IRS 1A. We discuss two possible models to explain the nature of IRS 1A: a thermal jet and an equatorial wind.Comment: 17 pages, 4 figures, to be published in A