232 research outputs found
Criar Ciência
Antes de desenvolver o tema ―Criar ciência‖, propriamente
dito, sinto a necessidade de definir alguns termos e de enquadrar
alguns conceitos. Em primeiro lugar, este capítulo dedica-se às
Ciências ditas Exatas e Naturais, sejam elas de caráter
fundamental ou aplicado, podendo provavelmente grande parte do
que aqui está escrito aplicar-se igualmente à Tecnologia. No
entanto, será que os processos e conceitos ligados à criação da
Ciência nestas áreas do conhecimento diferem dos que regem as
Ciências Humanas e Sociais? Provavelmente não, mas cabe ao
leitor responder a esta pergunta através dos textos aqui
apresentados. Em segundo lugar, as próprias Ciências ditas Exatas
e Naturais abrangem mundos tão diversos e distintos, tanto no que
diz respeito às escalas abrangidas (espaciais ou temporais), como
ao seu próprio estado de desenvolvimento, pelo que me é
obviamente impossível abordar estas ciências no seu conjunto.
Com estas palavras exemplifico perfeitamente, o dilema da maior
parte dos cientistas: Como falar de um tema sabendo
perfeitamente que o que se irá dizer, só se verifica para alguns
casos específicos ou até mesmo para uma grande maioria, mas
nunca para tudo e todos
Regional sea level change study based on estuarine sediment color and biogeochemistry - preliminary results
Coastal zones play a significant role in the regional development and have been an important area for human occupation through time. The study of estuarine sediments applied to sea level changes had always been of extreme importance, as it reflects the coastal line evolution, either by local, regional or global changes
An attempt to use color as a tool for high resolution correlations between estuarine sedimentary cores from Algarve (Portugal)
Nowadays, paleoenvironmental and climatological researches focus on studying shortterm
climatic changes and one of the more sensitive environments for recording those
short-term climatic variations are the high sedimentation rate of coastal regions. Accordingly,
4 estuaries from the Algarve region, south of Portugal, have been cored
in order to study sedimentary and climatic variations during recent times (c.a. 5000
yrs). For this purpose, we applied sampling and analytical techniques from deep-sea
studies, allowing the acquirement of almost continuous data profiles, as the color data
obtained with the spectrophotometer Colortron
Is it possible to use "twin cores" as a unique sedimentary record? An experimental design based on sediment color
Sedimentary cores are widely used for studying Quaternary records. However, the
amount of sediment that is available is proportional to the diameter of the core, which is rarely
bigger than 15 cm. One way to obtain more sediment is to use two cores retrieved from almost
the same location and use them as if they represent a unique sedimentary record. In the present
work, an experimental design has been applied to verify if “twin cores” from an estuary can be
considered as representing the same sedimentary record with twice the amount of sediment to
study. Because sediment can be characterized based on its color, the variables used as
replicates in the experimental design are the three Lab CIE colors acquired with a X-Rite
Colortron spectrophotometer. Sediment cores were retrieved from the upper saltmarsh of Gilão
River’s estuary, southern Portugal. Twin cores, with in between distances of 50 cm, 100 cm
and 200 cm, from two different sites were analysed. Results from a nested ANOVA show that
even for the closest twin cores (50 cm apart) there is at least one color variable that shows
significant variations between the profiles of both cores. These results clearly show that “twin
cores” cannot be used as a unique sedimentary record without any previous testing, at least in
such transitional regions
Organic carbon accumulation in coastal zones since the last glacial maximum? A clue for varying atmospheric CO2 levels?
It is a generally accepted concept that the carbon storage within the principal earth surface reservoirs varies in a multitude
of time scales. The shallow water continental margins belong to the most fertile areas in terms of organic carbon (OC)
production and are also very effective carbon traps
Shore platforms as a proxy for sea level changes
Shore platforms show several morphological features that can be use as
proxies for sea level changes. However, they are frequently difficult to date
and form in tidal ranges that may overcome the relative mean sea level (rmsl)
changes
Paleomagnetism in speleothems: influence of calcite growth dip on the natural remanent magnetization
Recent studies recognized speleothems as excellent recorders of the Earth’s magnetic field. However, some
questions remain about the origin of the natural remanent magnetization and about the influence of the speleothem shape on the recorded magnetic directions.info:eu-repo/semantics/publishedVersio
Speleothem shape and natural remanent magnetization
Speleothems might be of interest for high-resolution reconstruction of the Earth’s magnetic field. However, little
is known about the influence of speleothem morphologies on their Natural Remanent Magnetization (NRM).info:eu-repo/semantics/publishedVersio
The material sources and processes during the infilling of estuaries in Algarve (South Portugal)
The actual estuary that occupies the Boina-Arade paleovalley
accommodated the Holocene sedimentary sequence
whose thickness does not exceed 35 m in the deepest zones,
as registered from geotechnical borehole data. We present here
the results of partial analyses of two continuous cores which
cross the Holocene sequence until the Pre-Quaternary
substratum. In the P5 core (Boina river), the sedimentary
column, which spans 20 m accumulated during ca 8500 years
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