582 research outputs found
Revelation of the voluntary information about Human Capital in the Annual Reports.
La normalización contable actual impide el registro de parte de la información sobre los intangibles de las diferentes empresas. Para atenuar esta situación, muchas empresas ofrecen datos voluntarios sobre ellos en la documentación contable que ofrecen a terceros. Este trabajo analiza la información voluntaria que exponen las empresas españolas cotizadas sobre los intangibles no reconocidos en el Balance, incidiendo en el lugar que ocupan dentro del Informe Anual. La principal conclusión de la investigación es que las empresas ofrecen la información voluntaria que más les interesa para sus propias motivaciones y, sin embargo, los usuarios de la Contabilidad Financiera necesitan una información más amplia y comparable sobre el Capital Humano.The Financial Accounting impedes the registration on behalf of the information on the intangible of the different companies. To attenuate this situation, many companies offer voluntary data on them in the accounting documentation. This work analyzes the voluntary information of the Spanish companies about the intangible, impacting in the place that they occupy inside the Annual Report. The main conclusion of the investigation is that the companies offer the voluntary information that more it interests them for their own motivations and, however, the users of the Financial Accounting need a wider and more comparable information on the Human Capital
Surface magnetism in ZnO/Co3O4 mixtures
We recently reported the observation of room temperature ferromagnetism in
mixtures of ZnO and Co3O4 despite the diamagnetic and antiferromagnetic
character of these oxides respectively. Here we present a detailed study on the
electronic structure of this material in order to account for this unexpected
ferromagnetism. Electrostatic interactions between both oxides lead to a
dispersion of Co3O4 particles over the surface of ZnO larger ones. As a
consequence, the reduction of Co+3 to Co2+ at the particle surface takes place
as evidenced by XAS measurements and optical spectrocopy. This reduction allows
to xplain the observed ferromagnetic signal within the well established
theories of magnetism.Comment: Accepted in Journal of Applied Physic
Long distance (>20 km) downstream detection of endangered stream frogs suggests an important role for eDNA in surveying for remnant amphibian populations
Background
Globally, amphibian species have suffered drastic population declines over the past 40 years. Hundreds of species are now listed as Critically Endangered, with many of these considered “possibly extinct”. Most of these species are stream-dwelling frogs inhabiting remote, montane areas, where remnant populations are hard to find using traditional surveys. Environmental DNA (eDNA) could revolutionize surveys for ‘missing’ and endangered amphibian populations by screening water samples from downstream sections to assess presence in the upstream catchments. However, the utility of this survey technique is dependent on quantifying downstream detection probability and distances.
Methods
Here we tested downstream detection distances in two endangered stream frogs (Litoria lorica and L. nannotis) that co-occur in a remote stream catchment in north-east Australia, and for which we know precise downstream distributional limits from traditional surveys. Importantly, the two last populations of L. lorica persist in this catchment: one small (~1,000 frogs) and one very small (~100 frogs). We conducted eDNA screening at a series of sites kilometers downstream from the populations using precipitation from two fixed water volumes (15 and 100 mL) and via water filtering (mean 1,480 L).
Results
We detected L. nannotis and the small L. lorica population (~1,000 frogs) at most sampling sites, including 22.8 km downstream. The filtration method was highly effective for far-downstream detection, as was precipitation from 100 mL water samples, which also resulted in consistent detections at the far-downstream sites (including to 22.8 km). In contrast, we had limited downstream detection success for the very small L. lorica population (~100 frogs).
Discussion
The ecological aspects of our study system, coupled with thorough traditional surveys, enabled us to measure downstream eDNA detection distances with accuracy. We demonstrate that eDNA from a small population of approximately 1,000 frogs can be detected as far as 22.8 km downstream from the population. Water filtration is considered best for eDNA detection of rare aquatic species—indeed it was effective in this study—but we also achieved far-downstream detections when precipitating eDNA from 100 mL water samples. Collecting small water volumes for subsequent precipitation in the lab is more practical than filtration when surveying remote areas. Our downstream detection distances (>20 km) suggest eDNA is a valuable tool for detecting rare stream amphibians. We provide recommendations on optimal survey methods
Diffusion of Mn interstitials in (Ga,Mn)As epitaxial layers
Magnetic properties of thin (Ga,Mn)As layers improve during annealing by
out-diffusion of interstitial Mn ions to a free surface. Out-diffused Mn atoms
participate in the growth of a Mn-rich surface layer and a saturation of this
layer causes an inhibition of the out-diffusion. We combine high-resolution
x-ray diffraction with x-ray absorption spectroscopy and a numerical solution
of the diffusion problem for the study of the out-diffusion of Mn interstitials
during a sequence of annealing steps. Our data demonstrate that the
out-diffusion of the interstitials is substantially affected by the internal
electric field caused by an inhomogeneous distribution of charges in the
(Ga,Mn)As layer.Comment: 11 pages, 5 figure
Uses, cultural significance, and management of peatlands in the Peruvian Amazon: Implications for conservation
Tropical peatlands play an important role in the global carbon cycle by acting as significant carbon stores. South America's largest peatland complex is located in the Loreto Region of the Peruvian Amazon. Here we present the first study of human relations with these peatlands, including their uses, cultural significance and current management, as well as implications for conservation, based on qualitative research with people living in two riverine rural communities. Our results indicate that peatlands are culturally ambiguous spaces, used mainly for hunting, palm fruit harvesting, and timber, but feared due to the dangers of getting lost, sinking into the ‘sucking’ ground, and being attacked by anacondas and/or mythical creatures. While the difficult terrain and remoteness of peatlands have thus far acted as natural barriers to their destruction through conversion to different land uses, overuse of natural resources is nevertheless a significant concern for people living in the peat-dominated landscape of the Peruvian Amazon, mixed with frustration about the lack of outside support to foster environmental conservation and economic opportunities. We explore how evaluations of the present situation differ across one indigenous and one mestizo community. We identify a range of nascent peatland conservation strategies, including seedling planting to regrow valuable (palm) trees, and the climbing of palm trees for harvesting fruit as opposed to felling them. We argue that peatland conservation could be combined with the development of sustainable management strategies, but that this would require sustained engagement by outside organisations with rapidly growing local communities in these areas.NERC; Scottish Funding Counci
Can environmental DNA be used to detect first arrivals of the cane toad, Rhinella marina, into novel locations?
Eradicating invasive species is difficult, but success is more likely when populations are small after arrival. The cane toad, Rhinella marina, is an invasive pest species that threatens native fauna worldwide. Increasingly, environmental DNA (eDNA) is used as a technique to monitor the presence of invasive species given its power to detect low numbers of individuals. We aimed to investigate eDNA persistence in freshwater at three different temperatures (25, 30 and 35°C) and eDNA detection thresholds for R. marina using controlled experiments in aquaria. For the latter, two water volumes and two cane toad exposure times were used (800 or 200 L volume with 5 or 30 min exposure). A 15‐ml water sample was collected from each replicated aquaria and preserved with 5 ml Longmire's buffer. Environmental DNA was extracted and four technical quantitative PCR replicates were analyzed targeting the cane toad 16S rDNA mitochondrial gene. Environmental DNA decayed rapidly in water and was reliably detected for up to 3 days after cane toad removal, regardless of the temperature treatment. Also, cane toad eDNA was detected in the water after a 5‐min initial exposure of a single individual in 800 L of water. Under the physical parameters tested here, a positive detection means that a cane toad has been in contact with the water body between 1 and 3 days prior to the sampling event. The results of the present study show the importance of eDNA for determining the presence of a species that occurs at low abundance in a small water body, such as at the onset of a cane toad invasion
Importancia del desarrollo de los medios alternativos de transporte de mercancías
La aceleración del proceso de mundialización de la economía y el comercio, unida a la consolidación del mercado interior comunitario, son circunstancias que han incrementado, de manera notable, la importancia estratégica de los medios de transporte como instrumentos clave para el desarrollo de la economía productiva. En este contexto, la competividad de la economía de la Unión Europea depende, cada vez en mayor medida, de un sistema de transporte eficaz y barato capaz de mover mercancías de una forma rápida, fiable, económica y segura.
La investigación analiza diversos aspectos particulares de los costes en las empresas de transporte marítimo y ferroviario. El trabajo comienza con el estudio de los diversos medios de transporte, incidiendo en la comparativa entre el transporte por carretera por un lado, y diversos medios alternativos por otro: tanto el transporte ferroviario como el naval. Una vez observado lo anterior, identificamos las posibles ventajas económicas, comerciales y medioambientales, que se producirían en un escenario a nivel europeo en que se produjera un trasvase de actividad comercial desde el transporte en carretera al ferroviario y naval. Para concluir, el trabajo sugiere una batería de medidas para potenciar la actividad naviera y ferroviaria dentro de la Unión Europea
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