5,848 research outputs found
Historical fire records at the two ends of Iberian Central Mountain system: Estrela massif and Ayllon massif
The Iberian Peninsula has a long history of fire, as the Central Mountain System, from the Estrela
massif in Portugal to the Ayllón massif in Spain, is a major fire-prone area. Despite being part of the same
natural region, there are different environmental, political and socio-economic contexts at either end,
which might have led to distinct human causes of wildfires and associated fire regimes. The hypothesis
for this research lies in the historical long-term relationship between wildfire risks and fire use practices
within a context of landscape dynamics. In addition to conducting an analysis of the statistical period,
a spatial and temporal multiscale approach was taken by reconstructing the historical record of prestatistical
fires and land management history at both ends of the Central Mountain System. The main
result is the different structural causes of wildland fires at either end of the Central Mountain System, with
human factors being more important than environmental factors in determining the fire regimes in both
contexts. The study shows that the development of the fire regime was non-linear in the nineteenth and
twentieth centuries, due to broader local human context factors which led to a shift in fire-use practicesLa Península Ibérica cuenta con una larga historia de incendios forestales. Es el caso del Sistema Central,
desde la Sierra de Estrela en Portugal a la Sierra de Ayllón en España, aunque las causas humanas y el
régimen de incendios difieren en función del contexto ambiental, político y socioeconómico en uno y otro
extremo de la cordillera. La validación de la hipótesis de trabajo, sobre la relación histórica entre el riesgo
de incendios y el uso del fuego en las actividades humanas, se ha llevado a partir de la reconstrucción del
registro histórico de incendios forestales y de la gestión del territorio, y mediante el análisis multiescalar espacio-
temporal de los incendios históricos y estadísticos. Como principal resultado se han identificado las
causas estructurales de incendios en las sierras de Estrela y Ayllón. Además, se ha demostrado la influencia
mayor de los aspectos humanos que de los físicos en la evolución del régimen de fuego. En conclusión,
este trabajo evidencia la evolución discontinua de los incendios forestales a lo largo de los siglos XIX y XX
debido a los factores contextuales humanos que influyen en el manejo tradicional del fuego a escala localinfo:eu-repo/semantics/publishedVersio
A software tool for monitoring legal minimum lenght of landings: Case study of a fishery in sourthern Spain
Herramienta de interés para el control y la gestión de pesqueríasThe regulation of minimum legal size(MLS) of catches is a tool widely applied in the management of fisheries resources, although the MLS does not always coincide with the length at first maturit(LFM). The optimization of this management tool requires a series of quality control in fish markets and transportation. A software application has been developed to make the control of the landings of several target species easier and faster. In order to test and make this tool operational,six species of commercial interest were selected: four species of fish hand two species of bivalves. It is proposed to estimate the proportion of illegal specimens in the studied lot from the proportion of illegal individuals found in the samples taken from this lot.The input data for the application are the minimum legal size(MLS) of the species and the total length(TL)of each specimen sampled. The out put data is a statistical summary of the percentage of specimens of size less than the legal minimum(TL<=MLS)within
different confidence intervals(90%,95% and 99%). The software developed will serve as a fast,efficient and easy to manage tool that allows inspectors to determine the degree of compliance on MLS control and to make a decision supported by statistical proof on fishing goods
Differentiated instruction: ‘to be, or not to be, that is the question’
Education systems around the world, faces the major challenge of including all children in schools. Differentiated instruction (DI) is proposed as a pedagogical approach that support social, emotional and academic success for all students in the context of heterogeneous classrooms. Although, recent research draws the attention to the inconsistent definitions and practices of DI. In this context, this qualitative study aimed at exploring the Portuguese teachers self-reported typical DI practices in mixed-ability classrooms. The participants were thirty-six teachers from kindergarten to middle school and came from a public-school cluster of five schools. The qualitative analysis carried out indicate a variety of practices under the concept of DI, ranging from practices aimed only at a group of students, based on low ability or special education needs, to practices aimed at building communities of learners. The majority of the self-reported practices described DI as simply giving one assignment to most pupils and fewer or easier activities to students who are struggling with their learning. Implications for initial teacher training and professional development programmes are discussed. © 2022 Informa UK Limited, trading as Taylor & Francis Group.info:eu-repo/semantics/publishedVersio
Energy spectrum and Landau levels in bilayer graphene with spin-orbit interaction
We present a theoretical study of the bandstructure and Landau levels in
bilayer graphene at low energies in the presence of a transverse magnetic field
and Rashba spin-orbit interaction in the regime of negligible trigonal
distortion. Within an effective low energy approach (L\"owdin partitioning
theory) we derive an effective Hamiltonian for bilayer graphene that
incorporates the influence of the Zeeman effect, the Rashba spin-orbit
interaction, and inclusively, the role of the intrinsic spin-orbit interaction
on the same footing. Particular attention is spent to the energy spectrum and
Landau levels. Our modeling unveil the strong influence of the Rashba coupling
in the spin-splitting of the electron and hole bands. Graphene
bilayers with weak Rashba spin-orbit interaction show a spin-splitting linear
in momentum and proportional to , but scales inversely proportional
to the interlayer hopping energy . However, at robust spin-orbit
coupling the energy spectrum shows a strong warping behavior near
the Dirac points. We find the bias-induced gap in bilayer graphene to be
decreasing with increasing Rashba coupling, a behavior resembling a topological
insulator transition. We further predict an unexpected assymetric
spin-splitting and crossings of the Landau levels due to the interplay between
the Rashba interaction and the external bias voltage. Our results are of
relevance for interpreting magnetotransport and infrared cyclotron resonance
measurements, including also situations of comparatively weak spin-orbit
coupling.Comment: 25 pages, 5 figure
Comparative study about heating systems for pultrusion process
Different heating systems have been used in pultrusion, where the most widely used heaters are planar resistances. The primary objective of this study was to develop an improved heating system and compare its performance with that of a system with planar resistances. In this study, thermography was used to better understand the temperature profile along the die. Finite element analysis was performed to determine the amount of energy consumed by the heating systems. Improvements were made to the die to test the new heating system, and it was found that the new system reduced the setup time and energy consumption by approximately 57%
Neutron-Capture elements in planetary nebulae: first detections of near-Infrared [Te III] and [Br V] emission lines
We have identified two new near-infrared emission lines in the spectra of
planetary nebulae (PNe) arising from heavy elements produced by neutron capture
reactions: [Te III] 2.1019 m and [Br V] 1.6429 m. [Te III] was
detected in both NGC 7027 and IC 418, while [Br V] was seen in NGC 7027. The
observations were obtained with the medium-resolution spectrograph EMIR on the
10.4m Gran Telescopio Canarias at La Palma, and with the high-resolution
spectrograph IGRINS on the 2.7m Harlan J. Smith telescope at McDonald
Observatory. New calculations of atomic data for these ions, specifically
A-values and collision strengths, are presented and used to derive ionic
abundances of Te and Br. We also derive ionic abundances of other
neutron-capture elements detected in the near-infrared spectra, and estimate
total elemental abundances of Se, Br, Kr, Rb, and Te after correcting for
unobserved ions. Comparison of our derived enrichments to theoretical
predictions from AGB evolutionary models shows reasonable agreement for solar
metallicity progenitor stars of 2 - 4 M. The
spectrally-isolated [Br V] 1.6429 m line has advantages for determining
nebular Br abundances over optical [Br III] emission lines that can be blended
with other features. Finally, measurements of Te are of special interest
because this element lies beyond the first peak of the s-process, and thus
provides new leverage on the abundance pattern of trans-iron species produced
by AGB stars.Comment: 9 pages, 1 figure, 4 tables. Accepted for publication in ApJ Letter
Permo-Carboniferous magmatism in the core of Pangaea (Southern Pyreness): a possible linkange between the Variscan and Cimmerian cycles?
In southern Europe and the western Mediterranean, Permo-Carboniferous magmatism is well represented in areas
of Iberia, the Alps, Sardinia and the Balkan Peninsula. In Iberia, the magmatism that has been related to the
Variscan orogeny is associated with syn-orogenic events at ca. 350-315 Ma and post-orogenic at ca. 310-295
Ma. In the southern Pyrenees there is Permo-Carboniferous sedimentary basins with a significant volume of
rhyolitic ignimbrites and andesitic flows. The Erill Castell-Estac, Cadí and Castellar de n’Hug basins are spatially
associated with the Boí, Montellá and Vielha granites and the Cardet dacitic dykes emplaced in Variscan basement
rocks. U-Pb SHRIMP dating of zircons extracted from these granites, an andesitic flow, a dacitic dyke and six
ignimbrites, revealed that magmatism was active from ca. 304 Ma to ca. 266 Ma. The scattering of zircon ages
in each sample shows that the history of melt crystallization was prolonged and complex. The reported ages of
the magmatic activity for the Southern Pyrenees in the range ca. 304-283 Ma (this study) fit in well with the
time interval of magmatism related to the early North-dipping subduction of the Western Paleotethys Ocean, the
subsequent development of Iberian orocline (Variscan cycle), and the large-scale bending and blocking of the
Paleotethys Ocean subduction at East of Iberia.In paleogeographic reconstructions of the Permo-Carboniferous, Iberia is located in the core of Pangaea to the
east of the probable Rheic Ocean suture and near the western end of the subduction zone of the Paleotethys
Ocean. The emplacement in Iberia of granites with ca. 310-278 Ma age occurred after the collision of Laurussia
and Gondwana, when the subduction of the Rheic Ocean was inactive. From a Variscan-cycle perspective, the
Permo-Carboniferous magmatism of the Pyrenees has been considered as post-orogenic. However, global paleogeographic
reconstructions put Iberia in between the Rheic Ocean suture and the still active subduction zone of the
Western Paleotethys Ocean. Therefore, the Permo-Carboniferous magmatism of Iberia, from a Cimmerian-cycle
perspective, may have accompanied the closing of the Paleotethys Ocean. During this stage of the evolution of
Pangaea, the east of Iberia was geologically affected by the active subduction zone of the Paleotethys Ocean. The
period ca. 310-285 Ma is marked by the development of an orocline that extends from Iberia to Armorica. The
northwards subduction of the western corner of Paleotethys probably caused orocline formation and consequent
large-scale bending and blocking of Paleotethys subduction immediately east of Iberia. The Permo-Carboniferous
magmatism of Iberia, coeval with this tectonic evolution, shows a mixed imprint of subduction and delamination
geochemical signatures. Although this may seem controversial, in our view the magmatic activity preserved in
the Southern Pyrenees could provide the missing link between the development of the Iberian orocline and the
continued subduction of easternmost segments of the Paleotethys Ocean (Cimmerian cycle) during the evolution
of Pangaea
Conformation-independent QSPR approach for the soil sorption coefficient of heterogeneous compounds
We predict the soil sorption coefficient for a heterogeneous set of 643 organic non-ionic compounds by means of Quantitative Structure-Property Relationships (QSPR). A conformation-independent representation of the chemical structure is established. The 17,538molecular descriptors derived with PaDEL and EPI Suite softwares are simultaneously analyzed through linear regressions obtained with the Replacement Method variable subset selection technique. The best predictive three-descriptors QSPR is developed on a reduced training set of 93 chemicals, having an acceptable predictive capability on 550 test set compounds. We also establish a model with a single optimal descriptor derived from CORAL freeware. The present approach compares fairly well with a previously reported one that uses Dragon descriptors.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada
Assessment of portuguese community forestry: using the Voluntary Guidelines on the Responsible Governance of Tenure and FAO community-based forestry framework
In the last five decades, Community-Based Forestry (CBF) has
become a subject of special attention. It is assumed that the transfer
of rights to local communities will improve forest management. In
Portugal more than 13% of the forest area belongs to local communities
(termed baldios). Following FAO tools, assessments of
Forest Tenure and CBF were conducted to evaluate the effectiveness
of four baldio management types. The results revealed the most
common challenges for baldios, vis- a-vis, rights associated with their
management, protection of these rights, weak land administration,
weak mechanisms for conflict resolution, problems with decentralized
state support, cash flow management, and environmental challenges
leading to wildfires, loss of biodiversity, and inadequate
control of pests and invasive species. Resolution of these challenges
is urgently needed at the legal, administrative and local levels.
Future research should include assessments of CBF in other
European countries to reduce the existing knowledge gapinfo:eu-repo/semantics/publishedVersio
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