28,095 research outputs found
On the anomalous mass defect of strange stars in the Field Correlator Method
We investigate general aspects of the mass defects of strange stars in the
context of the Field Correlator Method, without magnetic field. The main
parameters of the model that enter the corresponding nonperturbative equation
of state of the quark gluon plasma are the gluon condensate and the large
distance static potential . We calculate mass defects of
stellar configurations in the central density range . In
general, the mass defects are strongly dependent on the model parameters. For a
large range of values of and , we obtain anomalous mass defects with
magnitudes around erg\,, of the same order of the observed energies
of gamma-ray bursts and neutrino emissions in SN1987A, and of the theoretically
predicted energies of the quark-novae explosions.Comment: 24 pages, 6 figure
Strange stars properties calculated in the framework of the Field Correlator Method
We calculate the strange star properties in the framework of the Field
Correlator Method. We find that for the values of the gluon condensate
and , which give a critical
temperature at , the sequences of strange
stars are compatible with some of the semi-empirical mass-radius relations and
data obtained from astrophysical observations.Comment: 26 pages, 10 figure
Optimal alarm systems for count processes
In many phenomena described by stochastic processes, the implementation of an alarm system becomes fundamental to predict the occurrence of future events. In this work we develop an alarm system to predict whether a count process will upcross a certain level and give an alarm whenever the upcrossing level is predicted. We consider count models with parameters being functions of covariates of interest and varying on time. This article presents classical and Bayesian methodology for producing optimal alarm systems. Both methodologies are illustrated and their performance compared through a simulation study. The work finishes with an empirical application to a set of data concerning the number of sunspot on the surface of the sun
Geomorphological heritage assessment: a methodology proposal
A metodologia de avaliação de património geomorfológico que é agora proposta, foi desenvolvida e
aplicada no Parque Natural de Montesinho, no âmbito de um projecto dedicado ao património geológico
dos parques naturais do NE de Portugal. Pretende-se que esta metodologia de avaliação possa ser
adoptada em outras áreas, independentemente das suas características e dimensão. Esta metodologia
baseia-se em três tipos de “objectos” com valor geomorfológico: locais isolados, áreas e miradouros. A
avaliação é realizada em duas etapas principais, a inventariação e a quantificação, suportadas pela
caracterização geomorfológica da área em análise. Na etapa da inventariação, após a identificação dos
locais potenciais é feita a sua avaliação qualitativa e a selecção dos locais de interesse geomorfológico,
os quais são caracterizados. A quantificação consiste na pontuação dos critérios relativos ao valor
geomorfológico e ao valor de gestão. Estes resultados permitem a comparação e a seriação final.During the last years, the geomorphological heritage of Montesinho Natural Park was assessed, in the
scope of a research project on the geological heritage of the Natural Parks of NE Portugal. The
assessment methodology proposed considers three types of geomorphosites and two main stages.
Geomorphosites can be single places, areas and panoramic viewpoints. The two main stages are the
inventory and the quantification. The inventory includes the identification and the qualitative assessment
of potential geomorphosites and therefore the selection and characterization of geomorphosites. The
quantification stage includes the numerical assessment and the final ranking. Geomorphological
(scientific, ecological, cultural and aesthetic) and management (protection and use) values are
numerically assessed using selected criteria.Centro de Estudos Geográficos, Universidade de Lisboa.Fundação para a Ciência e a Tecnologia (FCT)
Geomorphosite assessment in Montesinho Natural Park (Portugal)
The Montesinho Natural Park (MNP), with an area of
about 750 km2, is one of the largest protected areas
in Portugal. Since its inauguration as a natural park in
1979, geological and geomorphological aspects have
not been taken into consideration in its nature conservation policies. Over the last few years, this deficit has been compensated with an assessment of its geomorphological heritage. The assessment was made possible due to a research project on the geological heritage of the natural parks of north-eastern Portugal. The assessment method propagated herein proposes a clear definition of three types of geomorphosites: single places, geomorphological areas or panoramic viewpoints. Further, it proposes as two-staged approach to assessment with inventory compilation followed by quantification of value. Inventory compilation, for example, involves the identification and qualitative assessment of potential geomorphosites and, therefore, the selection and characterization of geomorphosites. The quantification stage includes the numerical assessment of sites and their final ranking. The values are numerically assessed using selected criteria. The implementation of this approach in the MNP led to the identification of 154 potential geomorphosites, of which only 26 were selected after the qualitative assessment or characterisation process. The numerical assessment of the sites and their ranking allowed a final selection of 13 sites for public use.(undefined
L’approccio del patrimonio geomorfologico nelle aree protette: geoconservazione contro geoturismo nei parchi naturali portoghesi
Artigo bilingue, em inglês e italianoAs in many other countries, geology and
geomorphology are absent from the majority of the
Portuguese protected areas statutes. These areas could be
places to protect landforms as a significant component of
the natural heritage. However, joining the preservation effort
to some ecotourism activities or other human activities could
damage or even destroy geomorphological sites. During the
last decade, multidisciplinary projects were developed in
protected areas from Northern Portugal, with special
emphasis in supporting geoconservation strategies and
making available products for public advertising of
geological and geomorphological features. This paper shows
the results of our activities on Montesinho Natural Park
(PNM) and International Douro Natural Park (PNDI).
Deliverables are being made available to protected areas
managers as scientific support for management plans. Other
products and initiatives have been implemented in order to
raise public awareness of geodiversity and geoconservation
and also to improve geotouristic offer. These products are
developed in dialogue with park managers who can include
them in management plans. Preserving geomorphological
sites and making them public at the same time can be
possible in protected areas. This approach can be applied to
other protected areas with positive results.Come in molti paesi, la geologia e la geomorfologia
sono praticamente assenti dagli statuti delle aree protette
del Portogallo. Queste aree potrebbero essere luoghi
dove proteggere le forme del rilievo come componenti significative
del patrimonio naturale. Tuttavia, gli sforzi per la
conservazione unitamente ad alcune attività di ecoturismo o
ad altre attività antropiche possono danneggiare o addirittura
distruggere i beni geomorfologici. Durante l’ultimo decennio,
sono stati sviluppati progetti multidisciplinari in aree
protette del nord del Portogallo, ponendo particolare attenzione
alle strategie di geoconservazione e sviluppando prodotti
per divulgare ad un pubblico vasto le caratteristiche
geologiche e geomorfologiche del paesaggio. In questo articolo
vengono illustrati i risultati delle attività svolte nel
Parco Naturale del Montesinho (PNM) e nel Parco naturale
internazionale del (PNDI). Una documentazione appropriata
è stata fornita alle aree protette come supporto scientifico
ai loro piani di gestione. Sono stati inoltre sviluppati
prodotti ed iniziative con lo scopo di aumentare la sensibilità
del grande pubblico ai temi della geodiversità e della geoconservazione
ed anche per migliorare l’offerta per un
turismo geologico. Questi prodotti sono stati realizzati di
concerto con i parchi e talvolta sono stati inseriti nei piani
di gestione. Conservare i beni geomorfologici e renderli allo
stesso tempo fruibili ai turisti è infatti possibile nelle aree
protette. Questo approccio può essere applicato ad altre aree
protette con risultati positivi
Unidades geomorfológicas e “áreas homogéneas” no Parque Natural de Montesinho
A paisagem no Parque Natural de Montesinho (PNM) é caracterizada por diversos elementos naturais e culturais, mas são sobretudo os de natureza geomorfológica que mais individualizam sectorialmente o parque. A litologia e a tectónica são as condicionantes principais da morfologia actual na área do PNM. Com os trabalhos de caracterização definiram-se como unidades geomorfológicas fundamentais do PNM: as serras; as superfícies de aplanamento; a depressão tectónica a norte de Bragança; os vales fluviais. Relacionados com estas unidades identificaram-se os principais elementos morfológicos da paisagem: aplanamentos a várias altitudes; relevos residuais; modelado granítico de pormenor; depressão tectónica a norte de Bragança; cristas e vertentes assimétricas em xistos; vales profundos; elementos geoculturais. Com base nesses factores, identificaram-se como “áreas homogéneas” no PNM: i) Quintanilha-Maçãs; ii) Alta Lombada; iii) Baixa Lombada; iv) Onor; v) Montesinho, vi) Escusanha-Soutelo; vii) Espinhosela-Mofreita; viii) Moimenta; ix) Coroa-Vinhais; x) Rabaçal-Assureira; xi) Pinheiros-Igrejinha; xii) Lomba; xiii) MenteMontesinho Natural Park (PNM) is characterised by a high diversity on natural and cultural elements although geomorphological features are the most impressive in the landscape. Lithology and tectonics are the main factors for landforms genesis in the PNM. The geomorphological characterisation supported the definition of the geomorphological units in PNM: mountains; erosion surfaces; tectonic basin at the north of Bragança; fluvial valleys. Related with these, the more representative geomorphological aspects on the landscape were identified: erosion surfaces; quartzitic ridges; granite landforms; tectonic basin; schist crests and asymmetric slopes; canyon valleys; cultural landforms. According o these elements, the following “homogenous areas” are proposed: i) Quintanilha-Maçãs; ii) Alta Lombada; iii) Baixa Lombada; iv) Onor; v) Montesinho, vi) Escusanha-Soutelo; vii) Espinhosela-Mofreita; viii) Moimenta; ix) Coroa-Vinhais; x) Rabaçal-Assureira; xi) Pinheiros-Igrejinha; xii) Lomba; xiii) Mente
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