Influence of asymmetry and nodal planes on high-harmonic generation in heteronuclear molecules

The relation between high-harmonic spectra and the geometry of the molecular orbitals in position and momentum space is investigated. In particular we choose two isoelectronic pairs of homonuclear and heteronuclear molecules, such that the highest occupied molecular orbital of the former exhibit at least one nodal plane. The imprint of such planes is a strong suppression in the harmonic spectra, for particular alignment angles. We are able to identify two distinct types of nodal planes. If the nodal planes are determined by the atomic wavefunctions only, the angle for which the yield is suppressed will remain the same for both types of molecules. In contrast, if they are determined by the linear combination of atomic orbitals at different centers in the molecule, there will be a shift in the angle at which the suppression occurs for the heteronuclear molecules, with regard to their homonuclear counterpart. This shows that, in principle, molecular imaging, which uses the homonuclear molecule as a reference and enables one to observe the wavefunction distortions in its heteronuclear counterpart, is possible.Comment: 14 pages, 7 figures. Figs. 3, 5 and 6 have been simplified in order to comply with the arXiv size requirement

Calagem e gessagem para o tomateiro e o meloeiro irrigados no Semi-Árido nordestino.

Instalou-se um experimento no Submédio São Francisco com o objetivo de avaliar o efeito da calagem e gessagem na produtividade e qualidade do tomate e melão. O delineamento foi em blocos ao acaso, com quatro repetições e sete tratamentos: 1) testemunha; 2) 0,5 vezes a necessidade de calagem (N.C.) na forma de calcário (0,5 x N.C. -Ca); 3) 1 x N.C. - Ca; 4) 2 x N.C. -Ca; 5) 0,5 x N.C., na forma de 2/3 de calcário e 1/3 de gesso (0,5 x N.C. - CaGe); 6) 1 x N.C -CaGe ; 7) 2 x N.C. -CaGe. Não se verificou efeitos significativos sobre a produtividade do tomate e a qualidade do melão. Com aplicação de 2 t/ha de calcário (1 x N.C -Ca) obteve-se uma produtividade de melão de 22,52 t/ha, significativamente superior à da testemunha, 16,77 t/ha, e reduziu-se a podridão apical do tomate em 80,4% em relação à da testemunha.Suplemento 2

Low redshift constraints on energy-momentum-powered gravity models

There has been recent interest in the cosmological consequences of energy-momentum-powered gravity models, in which the matter side of Einstein's equations is modified by the addition of a term proportional to some power, $n$, of the energy-momentum tensor, in addition to the canonical linear term. In this work we treat these models as phenomenological extensions of the standard $\Lambda$CDM, containing both matter and a cosmological constant. We also quantitatively constrain the additional model parameters using low redshift background cosmology data that are specifically from Type Ia supernovas and Hubble parameter measurements. We start by studying specific cases of these models with fixed values of $n,$ which lead to an analytic expression for the Friedmann equation; we discuss both their current constraints and how the models may be further constrained by future observations of Type Ia supernovas for WFIRST complemented by measurements of the redshift drift by the ELT. We then consider and constrain a more extended parameter space, allowing $n$ to be a free parameter and considering scenarios with and without a cosmological constant. These models do not solve the cosmological constant problem per se. Nonetheless these models can phenomenologically lead to a recent accelerating universe without a cosmological constant at the cost of having a preferred matter density of around $\Omega_M\sim0.4$ instead of the usual $\Omega_M\sim0.3$. Finally we also briefly constrain scenarios without a cosmological constant, where the single component has a constant equation of state which needs not be that of matter; we provide an illustrative comparison of this model with a more standard dynamical dark energy model with a constant equation of state.Comment: 13+2 pages, 12+1 figures; A&A (in press

Exploring nest destruction and bird mortality in mown Mediterranean dry grasslands: an increasing threat to grassland bird conservation

In recent years, haying has extended to Iberian Mediterranean dry grasslands potentially impacting on grassland bird ecology. We evaluated the impact of haying on a grassland bird community of South Portugal. Our main goals were: (1) to investigate the exposure of different species to haying, (2) to investigate potential removal of nests and dead birds from hayed fields by haying machinery using the ratio (REC) between the expected number of records and the number of records collected and (3) to link clutch destruction and bird mortality with haying management practices. Hayed fields were surveyed for signs of breeding and birds censused prior to mowing. Linear models were computed, linking the REC with haying machinery and sward properties. GLMs and model averaging were used to obtain models linking clutch destruction, bird mortality and haying management variables. Only 4 % of records evidenced successful nesting attempts (N = 177). REC evaluation suggested high nest or dead bird removal by the machinery, particularly in fields with lower vegetation biomass prior to cutting. Sickle bar mowers and one-rotor rotary rakes returned higher REC but lower probability of found nests removed from the original nesting sites comparatively to discs mowers and wheel rakes. Higher probabilities of mortality events were found in fields mown earlier (but not in all years). On the other hand, lower mortality was found in fields raked with two-rotor rotary rakes. Delayed haying, silage production in temporary crops and the use haying machinery enabling simultaneously mowing and gathering hay in lines are discussed as management alternatives

Installation and data analysis of a small network of SAR corner reflectors in Fogo, Cape Verde

Since early ninety’s Synthetic Aperture Radar Interferometry (InSAR) has been exploited for geophysical applications. InSAR technique is capable to capture information on surface deformation and can be a useful tool for monitoring active seismic and volcanic areas. Despite the capability of SAR sensors to operate in all weather and day/night conditions, SAR signal is affected by different source of noise (e.g. water vapour or instrumental noise) [Hanssen, 2001]. These disturbing sources affect the accuracy of InSAR deformation map, especially for time series analysis, and the quality control of InSAR measurements, either standard differential interferometry and Persistent Scatterers Interferometry (PSI), is not an easy task. A fruitful solution is represented by the adoption of passive Corner Reflectors (CRs). CRs can provide point measurements with high level of confidence with sub-centimeter accuracy [Marinkovic et al, 2007], thanks to their high backscattered signal value, and representing strong persistent scatterers to be used for calibrating and validating SAR (from InSAR and PSI technique) deformation map. Indeed, CRs can maintain their interferometric phase stable during time. Additionally, CRs can also be exploited to calibrate the amplitude SAR signal, and to provide reference points for geocoding purposes. Here we present the design, realization and installation of a small CRs network on the Fogo Volcano island, Cape Verde. This activity has been done in the framework of the European project MIAVITA, MItigate and Assess risk from Volcanic Impact on Terrain and human Activities

Enhancement of bichromatic high-harmonic generation with a high-frequency field

Using a high-frequency field superposed to a linearly polarized bichromatic laser field composed by a wave with frequency $\omega$ and a wave with frequency $2\omega$, we show it is possible to enhance the intensity of a group of high harmonics in orders of magnitude. These harmonics have frequencies about 30% higher than the monochromatic-cutoff frequency, and, within the three-step-model framework, correspond to a set of electron trajectories for which tunneling ionization is strongly suppressed. Particular features in the observed enhancement suggest that the high-frequency field provides an additional mechanism for the electron to reach the continuum. This interpretation is supported by a time-frequency analysis of the harmonic yield. The additional high frequency field permits the control of this group of harmonics leaving all other sets of harmonics practically unchanged, which is an advantage over schemes involving only bichromatic fields.Comment: 6 pages RevTex, 5 figures (ps files), Changes in text, figures, references and equations include

High-harmonic generation from a confined atom

The order of high harmonics emitted by an atom in an intense laser field is limited by the so-called cutoff frequency. Solving the time-dependent Schr\"odinger equation, we show that this frequency can be increased considerably by a parabolic confining potential, if the confinement parameters are suitably chosen. Furthermore, due to confinement, the radiation intensity remains high throughout the extended emission range. All features observed can be explained with classical arguments.Comment: 4 pages(tex files), 4 figures(eps files); added references and comment

Cultivos da cebola e do tomate industrial.

Manejo da cultura. Recomendacoes tecnicas e coeficientes tecnico para o plantio.bitstream/item/137803/1/ID-7006.pdfApostila do Curso de Atualizacao Tecnica para Engenheiros Agronomos do Banco do Brasil, Petrolina, 1995

Climate change perception: Driving forces and their interactions

Public perception of climate change can either facilitate or hinder the implementation of climate policies. This perception is dependent on a number of influencing factors, called drivers, in ways that are still not clearly understood. Our study quantifies the relative strength of drivers of climate change perception, taking into account differences in the social, political, geographical, economic and educational identities of any considered community. In addition to investigating the direct influence of the main drivers on climate change perception, we particularly examine the interactions among drivers, identifying in this way indirect pathways of influence. We find that perceptions are directly influenced by the share of principles and ideals within a community and by the physical experience of weather change. Indirect influences are found to be related to the level of development of a community, to its level of social interaction (i.e. individualistic vs. communitarian), and to the spread of climate change information. A deeper understanding of interactions among drivers should prove especially useful for the design of effective climate change mitigation and adaptation measures. © 2020 Elsevier LtdThe authors would like to thank Marta Olazabal and Sebastien Foudi (BC3) for their valuable reflections when developing the manuscript, as well as the editor and two anonymous reviewers whose comments helped improving this work. This research is supported by the Basque Government through the BERC 2018-2021 program and by the Spanish Ministry of Economy and Competitiveness MINECO through BC3 María de Maeztu excellence accreditation MDM-2017-0714. SHF and MBN acknowledge also financial support from Ramón y Cajal Research Grants of the Ministry of Economy and Competitiveness of Spain (Refs. RYC-2012-12167 and RYC-2013-13628)

Thermodynamics of Pseudo-Hermitian Systems in Equilibrium

In study of pseudo(quasi)-hermitian operators, the key role is played by the positive-definite metric operator. It enables physical interpretation of the considered systems. In the article, we study the pseudo-hermitian systems with constant number of particles in equilibrium. We show that the explicit knowledge of the metric operator is not essential for study of thermodynamic properties of the system. We introduce a simple example where the physically relevant quantities are derived without explicit calculation of either metric operator or spectrum of the Hamiltonian.Comment: 9 pages, 2 figures, to appear in Mod.Phys.Lett. A; historical part of sec. 2.1 reformulated, references corrected; typos correcte