8,206 research outputs found
Seaweed Aquaculture and Marine Biotechnology
Macroscopic marine algae, typically known as macroalgae or seaweeds, form an important living resource of the oceans, as primary producers. People have collected seaweeds for food, both for humans and animals for millennia. They also have been a source of nutrient rich fertilizers, as well as a source of gelling agents known as phycocolloids. More recently macroalgae are playing significant roles in medicine and biotechnology. Although Biotechnology and in particular marine biotechnology may have different meanings for different people, under the present context we will consider a broader definition. Marine biotechnology consists on the use of biological knowledge and/or the application of biological techniques on marine organisms, for the development of products in some way beneficial for humans. Seaweed aquaculture is, therefore a biotechnology activity. It is also one that can allow for further development of the industry. Today, seaweed cultivation techniques are standardized, routine and economical. Several factors, including understanding the environmental regulation of life histories and asexual propagation of thalli, are responsible for the success of large-scale seaweed cultivation. Presently, seaweed aquaculture represents approximately 23% of the world’s aquaculture production, including fish, crustaceans and other animals. A promising approach for the development of seaweed aquaculture, and aquaculture in general, is the integrated multi-trophic aquaculture (IMTA). In these systems, fed-aquaculture is combined with extractive organisms like bivalves and/or algae. The constraints and advantages of IMTA will be discussed. In particular, land based IMTA systems allow for much greater environmental and input controls. Traceability, security of supply, high-quality standards and safety should be the future of seaweed aquaculture and contribute for the development of marine biotechnology.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
Particle identification with the AMS-02 RICH detector: search for dark matter with antideuterons
The Alpha Magnetic Spectrometer (AMS), whose final version AMS-02 is to be
installed on the International Space Station (ISS) for at least 3 years, is a
detector designed to measure charged cosmic ray spectra with energies up to the
TeV region and with high energy photon detection capability up to a few hundred
GeV, using state-of-the art particle identification techniques. It is equipped
with several subsystems, one of which is a proximity focusing Ring Imaging
Cherenkov (RICH) detector equipped with a dual radiator (aerogel+NaF), a
lateral conical mirror and a detection plane made of 680 photomultipliers and
light guides, enabling precise measurements of particle electric charge and
velocity (Delta beta / beta ~ 10^-3 and 10^-4 for Z=1 and Z=10-20,
respectively) at kinetic energies of a few GeV/nucleon. Combining velocity
measurements with data on particle rigidity from the AMS-02 Tracker (Delta R /
R ~ 2% for R=1-10 GV) it is possible to obtain a reliable measurement for
particle mass. One of the main topics of the AMS-02 physics program is the
search for indirect signatures of dark matter. Experimental data indicate that
dark, non-baryonic matter of unknown composition is much more abundant than
baryonic matter, accounting for a large fraction of the energy content of the
Universe. Apart from antideuterons produced in cosmic-ray propagation, the
annihilation of dark matter will produce additional antideuteron fluxes.
Detailed Monte Carlo simulations of AMS-02 have been used to evaluate the
detector's performance for mass separation, a key issue for anti-D/anti-p
separation. Results of these studies are presented.Comment: 5 pages. Contribution to the 20th European Cosmic Ray Symposium
(Lisbon 2006). Presenter: Rui Pereir
Particle identification with the AMS-02 RICH detector: D/p and anti-D/anti-p separation
The Alpha Magnetic Spectrometer (AMS), whose final version AMS-02 is to be
installed on the International Space Station (ISS) for at least 3 years, is a
detector designed to measure charged cosmic ray spectra with energies up to the
TeV region and with high energy photon detection capability up to a few hundred
GeV, using state-of-the art particle identification techniques. Among several
detector subsystems, AMS includes a proximity focusing RICH enabling precise
measurements of particle electric charge and velocity. The combination of both
these measurements together with the particle rigidity measured on the silicon
tracker endows a reliable measurement of the particle mass. The main topics of
the AMS-02 physics program include detailed measurements of the nuclear
component of the cosmic-ray spectrum and the search for indirect signatures of
dark matter. Mass separation of singly charged particles, and in particular the
separation of deuterons and antideuterons from massive backgrounds of protons
and antiprotons respectively, is essential in this context. Detailed Monte
Carlo simulations of AMS-02 have been used to evaluate the detector's
performance for mass separation at different energies. The obtained results and
physics prospects are presented.Comment: 5 pages. Contribution to the Sixth International Workshop on New
Worlds in Astroparticle Physics (Faro 2007). Presenter: Rui Pereir
A Vertente Europeia-Continental e a Vertente Atlântico-Global na Política Externa Portuguesa
No presente artigo, propomo-nos analisar as
vertentes europeia-continental e atlânticoglobal
na política externa portuguesa. Começamos
por fazer uma breve retrospectiva
evolutiva, identificando três grandes modelos
de inserção internacional de Portugal, que
correspondem a momentos históricos específicos.
Seguidamente, detemo-nos nos vectores
de modernização e compensação, associando
o primeiro vector à matriz europeia-continental
e o segundo à atlântico-global. Argumentamos,
nomeadamente, que um deve ser indissociável
do outro, sob pena da política externa portuguesa
ser reduzida a uma condição cada vez
mais periférica pelo que poderá perder relevância.
Por último, reflectimos sobre as condições
de afirmação de Portugal no mundo,
destacando elementos incontornáveis como a
projecção da língua, a ligação ao mar e a vocação
universalista do povo português, chamando
a atenção para a necessária adaptação da nossa
diplomacia ao novo contexto de acção externa
do Estado, que pressupõe uma articulação coerente
e equilibrada entre as dimensões política,
económica e cultural
Cosmic ray velocity and electric charge measurements with the AMS/RICH detector: prototype results
The Alpha Magnetic Spectrometer (AMS) to be installed on the International
Space Station (ISS) will measure charged cosmic ray spectra of elements up to
iron, in the rigidity range from 1 GV to 1 TV, for at least three years. AMS is
a large angular spectrometer composed of different subdetectors, including a
proximity focusing Ring Imaging CHerenkov (RICH) detector. This will be
equipped with a mixed radiator made of aerogel and sodium fluoride (NaF), a
lateral conical mirror and a detection plane made of 680 photomultipliers
coupled to light guides. The RICH detector allows measurements of particle's
electric charge up to iron, and particle's velocity. Two possible methods for
reconstructing the Cherenkov angle and the electric charge with the RICH will
be discussed.
A RICH prototype consisting of a detection matrix with 96 photomultipliers, a
segment of a conical mirror and samples of the radiator materials was built and
its performance was evaluated using ion beam data. Results from the last test
beam performed with ion fragments resulting from the collision of a 158
GeV/c/nucleon primary beam of indium ions (CERN SPS) on a lead target are
reported. The large amount of collected data allowed to test and characterize
different aerogel samples and the NaF radiator. In addition, the reflectivity
of the mirror was evaluated. The data analysis confirms the design goals.Comment: 5 pages. Contribution to the 20th European Cosmic Ray Symposium in
Lisbon, Portugal. September 5th-8th 2006. Presenter: Luisa Arrud
Raça, Sangue e Robustez Os paradigmas da Antropologia Física
Por toda a primeira metade do século XX a Antropologia colonial portuguesa esteve quase
que totalmente entregue a uma orientação antropobiológica. A denominada «escola do Porto»,
na qual pontificava o professor catedrático de medicina Mendes Corrêa, assegurou todas as
«missões antropológicas» oficialmente instituídas para as colónias. A mais sucedida de todas
essas campanhas de investigação foi a dirigida por um seu assistente, Santos Júnior, também
ele médico e professor na Faculdade de Medicina do Porto. Entre 1937 e 1956, a Missão
Antropológica de Moçambique procedeu ao exaustivo levantamento antropométrico das populações
africanas da colónia. A Etnologia, ou a simples recolha etnográfica, eram ignoradas, deixadas
ao cuidado da curiosidade diletante dos mais diversos agentes da colonização, missionários,
militares, funcionários administrativos, comerciantes e fazendeiros.
Porque foi tão importante para o desígnio colonial português a Antropologia Física é o que
se procura responder neste artigo. E, em sequência, tentar perceber porque no início da segunda
metade do século XX foi a Antropologia Física tão subitamente substituída pela Etnologia
colonial.Universidade de Nova Lisbo
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