23 research outputs found
Interpretation of gravity data to delineate structural features connected to low-temperature geothermal resources at Northeastern Portugal
A great number of low-temperature geothermal fields occur in Northern-Portugal related to fractured rocks. The most important superficial manifestations of these hydrothermal systems appear in pull-apart tectonic basins and are strongly conditioned by the orientation of the main fault systems in the region. This work presents the interpretation of gravity gradient maps and 3D inversion model produced from a regional gravity survey. The horizontal gradients reveal a complex fault system. The obtained 3D model of density contrast puts into evidence the main fault zone in the region and the depth distribution of the granitic bodies. Their relationship with the hydrothermal systems supports the conceptual models elaborated from hydrochemical and isotopic water analyses. This work emphasizes the importance of the role of the gravity method and analysis to better understand the connection between hydrothermal systems and the fractured rock pattern and surrounding geology. (c) 2013 Elsevier B.V. All rights reserved
Levantamentos geofísicos no setor português da Faixa Piritosa Ibérica: perspetiva global da sua importância em prospeção de sulfuretos maciços e interpretação geológica
ABSTRACT: The application of geophysical techniques to massive
sulphide deposits exploration has proven to be a success in the Iberian
Pyrite Belt (IPB) metallogenetic province, both in Portugal and in Spain.
Several hidden deposits were discovered through the interpretation of
geological models, supported by geophysical data collected in land and
airborne surveys, as well as applied using down hole techniques in
selected drill holes. This paper presents an overview of the methodologies
applied in Portugal in the South Portuguese Zone (SPZ) geological
domain, where the IPB is included, mostly by the LNEG and mining
companies, with emphasis on the interpretation of the regional gravity,
magnetometry and radiometry surveys, published in 1/400 000 scale by
the EXPLORA/Alentejo2020 Project. In this regional mapping program,
the large volume of data collected by LNEG and mining companies since
the 1960’s was compiled and processed. The integrated interpretation and
correlation between these methods will enable a better planning of new
IPB exploration investments. IPB Volcano-Sedimentary Complex (VSC,
Famennian to Late Visean age) lineaments are well defined in the gravity
and magnetic fields along the IPB western region (e.g. Alcoutim/Neves Corvo/Montinho/Sesmarias/Lousal/Caveira). Aeromagnetic data also
reflect deep and large anomalies related with the SPZ basement. A rock
density database is presented and used to interpret the gravity data.
Radiometric map (Natural Radioactivity), based mostly in airborne
radiometric surveys, show contrasts between rocks in Paleozoic,
Mesozoic and Cenozoic formations and correlations with geological and
hydrothermal mapping are highlighted. The use of geophysical
techniques is particularly critical in areas where VSC is concealed by
younger sediments (e.g. Baixo Alentejo Flysch Group and/or Cenozoic
formations), allowing the selection of target areas. Case studies are
discussed based on electromagnetic, seismic and magnetotelluric methods
and on the high mineral potential of defined targets. Multilayered data
correlation (geophysics including petrophysical data, geochemistry and
stratigraphic high-resolution models) is a key prospecting methodology
and is essential for the accurate modelling of ore horizons and geological
structures. Considering the IPB potential for VMS deposits, including the
possible discovery of new giant (> 200 Mt) deposits, an increase of
investment in new geophysical methods can be predicted. LNEG
development of R&D projects such as EXPLORA/Alentejo2020 and
SmartExplorationTM/H2020 also contribute to a favourable setting in the
province, both in near mining and green fields scenarios. Thus, new
discoveries are expected, like others made in the recent times in the IPB
Portuguese sector, such as Lagoa Salgada (SFM, 1992, SFM;
Redcorp/EDM, 2011; Redcorp/Ascendant/EDM, 2017), Semblana
(Somincor-AGC-Lundin Mining, 2010), Monte Branco (Somincor Lundin Mining, 2012) and Sesmarias (Maepa/Avrupa, 2014). The
importance of these data goes beyond the mineral exploration purpose.
Since some of them use rock and mineral physical properties that can be
related with environmental contamination (e.g. radiometry and
magnetics) they can also be used in geochemical background studies, acid
mine drainage and metal dispersion. Therefore, they can also promote a
deeper knowledge in other areas of research related with environment
preservation.RESUMO: A aplicação de técnicas de prospeção geofísica na pesquisa de
jazigos de sulfuretos maciços na Faixa Piritosa Ibérica (FPI) tem-se
revelado um sucesso em Portugal e em Espanha. Vários jazigos ocultos
foram descobertos a partir da interpretação de modelos geológicos, com o
apoio de dados geofísicos recolhidos em levantamentos terrestres,
aerotransportados ou em profundidade, em sondagens (diagrafias). Neste
artigo, apresenta-se uma análise das metodologias aplicadas
principalmente pelo LNEG e empresas mineiras em Portugal, na Zona
Sul Portuguesa (ZSP), onde se insere a FPI. Destaca-se a interpretação
dos levantamentos regionais, esc. 1/400 000, de gravimetria,
magnetometria e radiometria (EXPLORA/Alentejo2020). Nestes
programas, foi feito o processamento de um volume de informação
significativo, a partir de dados obtidos desde a década de 1960. Neste
contexto indicam-se diversos alinhamentos de gravimetria e de
aeromagnetometria relativos a unidades geológicas com elevado
potencial mineiro, como o Complexo Vulcano-Sedimentar (CVS, idade
Famenniano a Viseano sup.), sobressaindo o eixo Alcoutim/Neves Corvo/Montinho/Sesmarias/Lousal/Caveira. Os dados de
aeromagnetismo refletem também anomalias com origens mais profundas
e relacionadas com a estrutura basal da ZSP. A base de dados de
densidades de rocha é utilizada na interpretação gravimétrica da FPI. O
mapa radiométrico (Radioatividade Natural), baseado fundamentalmente
em radiometria aeroportada (contagens totais) mostra o contraste à
superfície de litologias das formações paleozoicas, mesozoicas e
cenozoicas, sendo salientado, no primeiro caso, a sua correlação com a
cartografia de alterações hidrotermais. Em áreas onde o CVS se encontra
subjacente sob sedimentos mais recentes (ex. Grupo Flysch Baixo
Alentejo e formações cenozoicas), o uso de técnicas geofísicas é
fundamental para a seleção de alvos. São também descritos exemplos
sobre a aplicação de métodos eletromagnéticos, sísmicos e
magnetotelúricos na identificação e caracterização de estruturas
geológicas. A análise integrada de diferentes métodos geofísicos,
complementados com informação geológica e geoquímica, constitui a
melhor metodologia de prospeção, sendo essencial para a pesquisa de
horizontes de mineralização. Considerando a FPI como uma das principais províncias metalogenéticas do mundo, é expectável que
venham a ocorrer mais investimentos e assim serem identificados novos
jazigos, inclusive com dimensão superior a 200 Mt. Através de projetos
ID como o EXPLORA/Alentejo2020 e SmartExplorationTM/H2020 o
LNEG contribui para um melhor conhecimento na FPI em cenários de
prospeção near mining e green fields. Nesta perspetiva, são esperadas
novas descobertas de jazigos à semelhança do que tem acontecido em
Portugal, como por exemplo Lagoa Salgada (SFM-1992, Redcorp/EDM 2011, Redcorp/Ascendant/EDM-2017), Semblana (Somincor-AGC Lundin Mining, 2010), Monte Branco (Somincor-Lundin Mining, 2012) e
Sesmarias (Maepa/Avrupa, 2014). A importância destes dados vai muito
para além da prospeção mineira. Uma vez que alguns métodos utilizam
propriedades físicas que podem ser relacionadas com contaminações
ambientais. Certos métodos geofísicos como radiometria e
magnetometria, resistividade e métodos elétricos em geral, podem ser
utilizados também em trabalhos de investigação sobre background
geoquímico, drenagem ácida de mina e dispersão de metais. Desta forma,
a aplicação destes métodos promove também um conhecimento mais
aprofundado noutras áreas de investigação relacionadas com a
preservação do ambiente.info:eu-repo/semantics/publishedVersio
FUMEPOC: Early detection of chronic obstructive pulmonary disease in smokers
<p>Abstract</p> <p>Background</p> <p>Currently is not feasible using conventional spirometry as a screening method in Primary Care especially among smoking population to detect chronic obstructive pulmonary disease in early stages. Therefore, the FUMEPOC study protocol intends to analyze the validity and reliability of Vitalograph COPD-6 spirometer as simpler tool to aid screening and diagnosis of this disease in early stages in primary care surgery.</p> <p>Methods / Design</p> <p>Study design: An observational, descriptive study of diagnostic tests, undertaken in Primary Care and Pneumology Outpatient Care Centre at San Juan Hospital and Elda Hospital. All smokers attending the primary care surgery and consent to participate in the study will undergo a test with Vitalograph COPD-6 spirometer. Subsequently, a conventional spirometry will be performed in the hospital and the results will be compared with those of the Vitalograph COPD-6 test.</p> <p>Discussion</p> <p>It is difficult to use the spirometry as screening for early diagnose test in real conditions of primary care clinical practice. The use of a simpler tool, Vitalograph COPD-6 spirometer, can help in the early diagnose and therefore, it could improve the clinical management of the disease.</p
Validity and reliability of transbronchial needle aspiration for diagnosing mediastinal adenopathies
<p>Abstract</p> <p>Background</p> <p>The aim is to assess the validity and reliability of transbronchial needle aspiration (TBNA) of mediastinal and hilar adenopathies and to evaluate factors predictive of TBNA outcome.</p> <p>Methods</p> <p>We performed an analysis of prospectively collected data of patients (n = 580) who underwent TBNA (n = 685) from January 1998 to December 2007 in our center. Validity and reliability were evaluated for the overall sample and according to specific pathology. Factors predicting the successful acquisition of diagnostic samples were analyzed by multivariate analysis.</p> <p>Results</p> <p>Overall sensitivity, specificity, accuracy, and positive and negative predictive (NPV) values for TBNA were 68%, 100%, 68.8%, 100%, and 10%, respectively. The most sensitive and accurate TBNAs were obtained for patients with small cell lung carcinoma and the worst results were for patients with lymphomas. NPV were similar for all pathologies. The most predictive factors of outcome were adenopathy size and the presence of indirect signs at the puncture site.</p> <p>Conclusion</p> <p>The sensitivity and accuracy of TBNA are high in small cell lung cancer, followed by other types of carcinoma, sarcoidosis, and tuberculosis, and low for lymphoproliferative diseases. The NPV of TBNA for all individual pathologies is low. The size of the adenopathy and the presence of indirect signs at the puncture site predict the achievement of diagnostic samples.</p
Factors Related with Hospital Attendance and Mortality in Patients with COPD: A Case?Control Study in a Real-Life Setting
Introduction: The rising trend in hospital admissions among patients with chronic obstructive pulmonary disease (COPD) is worrying, not only because of the increasing costs, but also because of the worsening quality of life. We aimed to identify the predictive factors of hospital admission, re-admission and mortality of COPD patients through using information exclusively registered in electronic clinical records.
Methods: We conducted a population-based case?control study. All data were sourced from the different information systems comprising the Galician Health Service electronic record database. We included in the study patients diagnosed with COPD (code R95 in the medical record), ? 35 years old and with at least one spirometry performed ? 3 years prior inclusion. We fitted three logistic regression models, each one to ascertain the factors that influence the probability of admission, re-admission, and mortality, and calculated odds ratios (OR) with their 95% confidence intervals (95% CI).
Results: COPD patients were admitted due to respiratory causes a mean of 1.51 times across the period December 2016?December 2017, with 55% requiring re-admission in the next 90 days. The factor most closely associated with the re-admission profile was home oxygen therapy (OR 3.06 95% CI 2.42? 3.87), followed by male gender (OR 2.01 95% CI 1.48? 2.72), a CHA2D-VASc scale score > 2 (OR 1.28 95% CI 1.16? 1.42), and severity by clinical risk group stratification (OR 1.14 95% CI 1.04? 1.26). Male sex (OR 1.47 CI 95% 1.04? 2.09), having been readmitted ? 2 times (OR 1.34 CI 95% 1.11? 1.61) and being ? 70 years old (OR 1.05 CI 95% 1.03? 1.08) increase the probability of dying from COPD during the study period.
Conclusion: These results confirm the complexity of management of COPD exacerbations, and indicate the need to establish strategies that would ensure continuity of care after hospital admission, with the aim of preventing re-admissions and death