Single-shot implementation of dispersion-scan for the characterization of ultrashort laser pulses

We demonstrate a novel, single-shot ultrafast diagnostic, based on the dispersion-scan (d-scan) technique. In this implementation, rather than scanning wedges to vary the dispersion as in standard d-scan, the pulse to be measured experiences a spatially varying amount of dispersion in a Littrow prism. The resulting beam is then imaged into a second-harmonic generation crystal and an imaging spectrometer is used to measure the two-dimensional trace, which is analyzed using the d-scan retrieval algorithm. We compare the single-shot implementation with the standard d-scan for the measurement of sub-3.5-fs pulses from a hollow core fiber pulse compressor. We show that the retrieval algorithm used to extract amplitude and phase of the pulse provides comparable results, proving the validity of the new single-shot implementation down to near single-cycle durations.Comment: 6 pages, 4 figure

The IACOB project. VI. On the elusive detection of massive O-type stars close to the ZAMS

The apparent lack of massive O-type stars near the zero-age main sequence (at ages < 2 Myr) is a topic widely discussed. Different explanations for this elusive detection have been proposed, but no firm conclusions have been reached yet. We reassess this empirical result benefiting from the high-quality spectroscopic observations of >400 Galactic O-type stars gathered by the IACOB and OWN surveys. We used temperatures and gravities from a iacob-gbat/fastwind spectroscopic analysis to locate our sample in the Kiel and spectroscopic HR diagrams. We evaluated the completeness of our sample of stars, observational biases using information from the Galactic O star catalog (GOSC), systematics of our methodology, and compare with other recent studies using smaller samples of Galactic O-type stars. We base our discussion on the spectroscopic HR diagram to avoid the use of uncertain distances. We performed a detailed study of the young cluster Trumpler-14 as an example of how Gaia cluster distances can help to construct the associated classical HR diagram. The apparent lack of massive O-type stars near the ZAMS with masses between 30 and 70 Msol persist even when spectroscopic results from a large, non-biased sample of stars are used. We do not find correlation between the dearth of stars and observational biases, limitations of our methodology, or the use of spectroscopic HR diagram instead of the classical one. Investigating the efficiency of mass accretion during the formation process we conclude that an adjustment of the accretion rate towards lower values could reconcile the hotter boundary of detected O-type stars and the theoretical birthline. Last, we discuss that the presence of a small sample of O2-O3.5 stars found closer to the ZAMS might be explained taking into account non-standard star evolution (e.g. binary interaction, mergers, or homogeneous evolution).Comment: 20 pages, 15 figures, accepted for publication in Astronomy & Astrophysic

Entomological fauna associated with Aguaribay : Mendoza (Argentina)

En los relevamientos de especias dañinas y benéficas presentes en el aguaribay (Schinus molle L. var. Areira), para inventariar su entomofauna se efectuaron observaciones en distintas zonas de Mendoza (Argentina) en 1988/91 y 1994/96, confirmando y actualizando la bibliografía. Se recolectó material a campo para su identificación sistemática. Se evaluaron daños y se los documentó fotográficamente. En el laboratorio se conservaron muestras con parasitoides hasta la aparición de adultos para su clasificación, registrándose 8 especies de Homoptera, 7 de Hymenoptera, 7 de Coleoptera, 5 de Lepidoptera, 4 de Diptera, 4 de Thysanoptera, 2 de Hemiptera y 2 de Neuroptera. Las principales especies que afectan al Aguaribay son Calophya sp. (Homoptera - Psyllidae), Ceroplastes grandis (Homoptera - Coccidae) y Aphis schinifoliae (Homoptera - Aphididae). También cuenta con una importante fauna benéfica: coccinélidos, parasitoides, sírfidos y crisópidos.Pest and beneficial species present in Schinus molle L. var. Areira were monitoring in order to obtain an inventory of its entomological fauna. It was made observations in different zones of Mendoza from 1988 to 1991, and then, between 1994 and 1996, it was confirmed further observations and it was brought up to day bibliographical revisions. It was collected material in field in order to made its systematic identification. Damages were evaluated and documented photographically. Samples with parasitoids were stored in laboratory until the appearance of adults for their classification. It was registered: 8 species of Homoptera, 7 of Hymenoptera, 7 of Coleop-tera, 5 of Lepidoptera, 4 of Diptera, 4 of Thysanoptera, 2 of Hemiptera and 2 of Neuroptera. The main pest are: Calophya sp. (Homoptera - Psyllidae), Ceroplastes grandis (Homoptera - Coccidae) and Aphis schinifoliae (Homoptera - Aphididade). Also, there is an important beneficial fauna: Coccinellidae, parasitoids, Syrphidae and Chrysopidae.Fil: Sáez, César C.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias BiológicasFil: Mácola, Guido S.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias BiológicasFil: Holgado, Miriam G.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias BiológicasFil: García Sáez, José G.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Biológica

The IACOB project. V. Spectroscopic parameters of the O-type stars in the modern grid of standards for spectral classification

The IACOB and OWN surveys are two ambitious complementary observational projects which have made available a large multi-epoch spectroscopic database of optical high resolution spectra of Galactic massive O-type stars. As a first step in the study of the full sample of (more than 350) O stars surveyed by the IACOB/OWN projects, we have performed the quantitative spectroscopic analysis of a subsample of 128 stars included in the modern grid of O-type standards for spectral classification. We use semi-automatized tools to determine the set of spectroscopic parameters that can be obtained from the optical spectrum of O-type stars. We also benefit from the multi-epoch character of the surveys to perform a spectroscopic variability study of the sample, accounting for spectroscopic binarity and variability of the main wind diagnostic lines. We provide a general overview of the stellar and wind parameters of this reference sample, and updated recipes for the SpT\,--\,Teff/log g calibrations for Galactic O-type stars. We evaluate our semi-automatized analysis strategy with $\sim$40 stars from the literature, and find a good agreement. The agreement between the synthetic spectra associated with fastwind best fitting models and the observed spectra is good for most targets, but 46 stars present a particular behavior of the wind diagnostic lines that cannot be reproduced by our grid of spherically symmetric unclumped models. These are potential targets of interest for more detailed investigations of clumpy winds and/or the existence of additional circumstellar components. Last, our variability study has led to the detection of signatures of spectroscopic binarity in 27\% of the stars and small amplitude radial velocity variations in the photospheric lines of another 30\%. Additionally, 31\% of the investigated stars show variability in the wind diagnostic lines.Comment: 20 pages, 18 figures, accepted for publication in Astronomy & Astrophysic

Continuous improvement planning through sustainability assessment of product-service systems

The paper presents a methodology for the integrated sustainability assessment of a product-service system lifecycle, with the purpose to support continuous improvement on the side both of the manufacturer and of the user. Its eight steps are an extension of ISO 14040 life cycle assessment and consider all three sustainability dimensions – economic, environmental and social – and a service perspective, using the service unit. A set of indicators for the three dimensions, aligned to the service unit concept, is proposed based on literature suggestions

Green Carbon: Making sustainable agriculture real

The concept of sustainable development has evolved from a mere movement for the protection of the environment, to other multidimensional approaches. Indeed, today it calls for a holistic approach, seeking to preserve and improve not only the environment, but also to achieve social equity and economic sustainability. In Europe, society demands quality and safe products, not only in the industrial sector but also in agriculture. According to FAO, sustainable agriculture development is a key element of the new global challenges to meet human food security needs at 2050. Unsustainable practices based on intensive soil tillage and agro-chemical applications have increased agri-environmental risks. Whereas world’s food needs are expected to increase by 70% by 2050, agricultural land in Europe will also have to face environmental, economic and social challenges related to sustainable agriculture. As a result, in the EU 2020 Strategy, it is expressed that the new Common Agricultural Policy (CAP) is required to contribute to smart, sustainable and inclusive growth, enhancing social well-being, providing ecosystem services, managing resources sustainably while avoiding environmental degradation. There is broad consensus within the scientific sector that human actions generate a large portion of the greenhouse gas (GHG) emissions, causing global warming. Certainly, Kyoto Protocol states it. According to the European Environmental Agency (EEA), there has been a decrease of 17% in GHG emissions between 1990 and 2009. However, EEA also stressed the importance of the agricultural contribution to total emissions (10.3%). The fossil fuel used in agricultural field operations, along with increasing CO2 emissions from soil through tillage, are considered to be one of the main direct sources of GHG emissions from agriculture sector. Increased inputs required to sustain conventional agriculture also adds significantly to total GHG emissions. Therefore, intensification of production through tillage, agro-chemicals and heavy machinery, which characterizes conventional agriculture in Europe, strongly contributes to increased net GHG emissions instead of mitigating global warming. Sustainable agricultural soil management is crucial for mitigating climate change, especially for the restoration of lost soil organic carbon. In fact, "Agricultural soils management" is recognized as one of the 15 most promising technology options for reducing GHG emissions in the COM (2005) 35 final "Winning the battle against global climate change." The Green Carbon Conference aims to show sustainable management of agricultural soils can help to agriculture mitigate and adapt to climate change, being compatible with the objectives of environmental protection, enhancing biodiversity and supporting farmers’ welfare along with many other environmental, economic and social benefits. Over the last decade, Conservation Agriculture has become known as a set of interlinked agricultural practices, of no or minimum mechanical soil disturbance, maintenance of soil mulch cover, and diversified cropping system, capable of: (a) overcoming several of the severe sustainability limitations of conventional agriculture; and (b) raising productivity, enhancing resilience, reducing degradation and increasing the flow of ecosystem services. The discussion around both the Soil Thematic Strategy initiated in 2002, and the JRC SoCo (Soil Conservation) project clearly recognized the potential of Conservation Agriculture in mitigating and even reversing the problems of soil erosion, soil organic matter decline, soil compaction, loss of biodiversity, climate change vulnerability, among others. Whereas Conservation Agriculture is now practiced successfully on more than 125 million hectares worldwide, Europe has shown to be reluctant with regard to its adoption, despite many promising results confirming its suitability in Europe. Therefore, this European Conference on Green Carbon provides an opportunity to take a leap forward in terms of sharing farmers experiences on Conservation Agriculture across Europe, reviewing the recent progress made in knowledge generation regarding Conservation Agriculture, and to disseminate the outcomes of the currently running LIFE+ Agricarbon (LIFE08 ENV/E/000129). The slogan of ‘Green Carbon’ chosen for this Conference attempts to clarify and highlight the indivisible yet vital link between soil organic carbon and the role that soil health plays in the sustainability of agricultural production and in the flow of ecosystem services. Nevertheless, the topics addressed by the Green Carbon Conference are not only related to the importance of soil organic carbon for the overall soil quality and health, but also include other sustainability issues intimately related to the role of soil carbon such as landscape scale ecosystem functions and services, climate change mitigation and carbon offset, and economic aspects. This Conference also seeks to alert and inform EU policy stakeholders and technical officers of the urgent need to adopt sustainable soil and production practices of Conservation Agriculture to contribute to the objectives of Europe 2020, the EU's growth strategy for the coming decades

Comportamiento en fritura de los aceites extraídos de la aceituna

In this article, the main studies on frying performance of olive-extracted oils, namely, virgin olive oils, olive oils and olive-pomace oils, are reviewed and discussed in relation to other vegetable oils. Firstly, the most relevant compositional data of olive-extracted oils and commonly used vegetable oils are reported, including modified seed oils developed for frying uses. The influence of the degree of unsaturation and of the minor compounds with protective effect during frying are discussed, with special reference to tocopherols, other phenolic compounds, phytosterols and squalene. Results on comparative behavior of olive-extracted oils and other vegetable oils reflect that all olive-extracted oils show great stability to thermal oxidation and are highly suitable for frying, due to their high content of oleic acid, low content of polyunsaturated fatty acids and occurrence of minor components with antioxidant activity or protective effects. Among olive-extracted oils, the scarce information published on used frying pomace-olive oils is noted.En este artículo se revisan los principales estudios sobre el comportamiento en fritura de los aceites extraídos de la aceituna, es decir, aceites de oliva virgen, de oliva y de orujo de oliva. En primer lugar se describe su composición, así como la de los aceites vegetales más utilizados y los aceites de semillas modificadas, y se comenta la influencia en fritura del grado de insaturación y de los componentes menores del aceite, especialmente tocoferoles, otros compuestos fenólicos, fitoesteroles y escualeno. Los estudios realizados en comparación con otros aceites vegetales reflejan la gran resistencia de los aceites extraídos de la aceituna a la oxidación térmica y su aptitud para la fritura, debido a sus altos contenidos en ácido oleico, bajos niveles de ácidos grasos poliinsaturados y presencia de componentes menores con actividad antioxidante o protectora. Entre los aceites extraídos de la aceituna, el comportamiento del aceite de orujo de oliva es el menos estudiado en fritura

Transcranial direct current stimulation (tDCS) over the left prefrontal cortex does not affect time-trial self-paced cycling performance: Evidence from oscillatory brain activity and power output

To test the hypothesis that transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) influences performance in a 20-min time-trial self-paced exercise and electroencephalographic (EEG) oscillatory brain activity in a group of trained male cyclists. There were no differences (F = 0.31, p > 0.05) in power output between the stimulation conditions: anodal (235W[95%CI 222–249 W]; cathodal (235W[95%CI 222–248 W] and sham (234W[95%CI 220–248 W]. Neither heart rate, sRPE nor EEG activity were affected by tDCS (all Ps > 0.05). tDCS over the left DLFC did not affect self-paced exercise performance in trained cyclists. Moreover, tDCS did not elicit any change on oscillatory brain activity either at baseline or during exercise. Our data suggest that the effects of tDCS on endurance performance should be taken with caution.This project was supported by grants from from the Spanish Ministerio de Economía, Industria y Competitividad-PSI2016-75956-P to D. S. and M.Z., a predoctoral grant from the Spanish Ministerio de Economía, Industria y Competitividad (BES-2014-069050) to L.F.C., and a Spanish “Ministerio de Educación, Cultura y Deporte” predoctoral grant (FPU14/06229) to D.H. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Mobilizing Greater Crop and Land Potentials with Conservation Agriculture

The engine that supplies food and agricultural products is the way we farm. The current dominant engine of conventional tillage farming based on the Green Revolution agriculture mind-set is faltering and needs to be replaced to meet the Sustainable Development Goals (SDGs) and the future food and agricultural demands by consumers and society. This chapter elaborates on the alternate no-till Conservation Agriculture (CA) paradigm (involving no-till seeding in soils with mulch cover and in diversified cropping systems). This new paradigm of CA is able to raise productivity sustainably and efficiently, reduce inputs, regenerate degraded land, minimize soil erosion, and harness the flow of ecosystem services. CA is an ecosystems approach to regenerative farming which is capable of enhancing the economic and environmental performance of crop production and land management that can contribute to achieving several SDGs. The new CA paradigm also promotes a mind-set change of producing ‘more from less’ inputs, the key attitude needed to move towards sustainable production based on agro-ecological intensification of output. CA is spreading globally in all continents at an annual rate of around 10 M ha of cropland. The current (in 2015/16) spread of CA is approximately 180 M ha, of which 48% is located in the Global South. CA not only provides the possibility of increased crop yields and profit for the low input smallholder farmer, it also provides a pro-poor rural and agricultural development model to support sustainable agricultural intensification in low income countries in an affordable manner for poverty alleviation, food security and economic development. However, for SDGs to contribute real lasting value to the quality of human life and to nature, the current and future human and ethical consequences of the uncontrolled consumer demands and pressures placed upon agricultural production by the food and agriculture system as a whole must be addressed

Optical vortex production mediated by azimuthal index of radial polarization

[EN]Special light beams are becoming more and more interesting due to their applications in particle manipulation, micromachining, telecommunications or light matter-interaction. Both spin and orbital angular momenta of light are exploited often in combination with spatially varying linear polarization profiles (e.g. radial or azimuthal distributions). In this work we study the interaction between those polarization profiles and the spin-orbit angular momenta, finding the relation involved in the mode coupling. We find that this manipulation can be used for in-line production of collinear optical vortices with different topological charges, which can be filtered or combined with controlled linear polarization. The results are valid for continuous wave and ultrashort pulses, as well as for collimated and focused beams. We theoretically demonstrate the proposal, which is further confirmed with numerical simulations and experimental measurements with ultrashort laser pulses.This work was partially funded by Junta de Castilla y León (SA287P18) and FEDER Funds; Spanish Ministerio de Economía y Competitividad (MINECO) (FIS2017-87970-R, EQC2018-004117-P); European Research Council (ENIGMA)