4,025 research outputs found
CIRN/GREC 2014 Campaign report
A cetacean survey campaign was performed around São Miguel Island (Azores) by Anacaona Sailing boat (GREC) from May 8th to May 17th and from July 4th to August 1st of 2014. The team conducted a total of 18 days of effort around the island. A total of 9 species were sighted during the survey: common dolphin (Delphinus delphis), atlantic spotted dolphin (Stenella frontalis), bottlenose dolphin (Tursiops trucnatus), stripped dolphin (Stenella coeruleoalba), risso’s dolphin (Grampus griseus), sperm whale (Physter macrocephalus), fin whale (Balaenoptera physalus), false killer whale (Pseudorca crassidens) and Blainville beaked whale (Mesoplodon densirostris). The common dolphin together with the Atlantic spotted dolphin were the most sighted species. Some differences in the distribution between the species can be appreciated in the corrected effort maps. Acoustic data is currently under study.info:eu-repo/semantics/publishedVersio
Uprolides N, O and P from the Panamanian Octocoral Eunicea succinea.
Three new diterpenes, uprolide N (1), uprolide O (2), uprolide P (3) and a known one, dolabellane (4), were isolated from the CHâ‚‚Clâ‚‚-MeOH extract of the gorgonian octocoral Eunicea succinea, collected from Bocas del Toro, on the Caribbean coast of Panama. Their structures were determined using spectroscopic analyses, including 1D and 2D NMR and high-resolution mass spectrometry (HRMS) together with molecular modeling studies. Compounds 1-3 displayed anti-inflammatory properties by inhibiting production of Tumor Necrosis Factor (TNF) and Interleukin (IL)-6 induced by lipopolysaccharide (LPS) in murine macrophages
CIRN/GREC 2013 Campaign report
A cetacean survey campaign was performed around São Miguel Island (Azores) by Anacaona Sailing boat (GREC) from July 13th to August 24th of 2013. The team conducted a total of 22 days of effort around the island. A total of 8 species was sighted during the survey: common dolphin (Delphinus delphis), atlantic spotted dolphin (Stenella frontalis), bottlenose dolphin (Tursiops trucnatus), stripped dolphin (Stenella coeruleoalba), risso’s dolphin (Grampus griseus), sperm whale (Physter macrocephalus), sei whale (Balaenoptera borealis) and beaked whales (Mesoplodon sp.). The common dolphin together with the atlantic spotted dolphin were the most sighted species. Some differences in the distribution between the species can be appreciated in the corrected effort maps. Acoustic data is currently under study.info:eu-repo/semantics/publishedVersio
Estudando e valorizando os cetáceos dos Açores
Nos Açores ocorrem pelo menos 25 espécies diferentes de cetáceos (baleias e golfinhos). Algumas podem observar-se facilmente durante todo o ano, mas outras são menos visÃveis, quer por ocorrerem apenas em épocas especÃficas quer pelo seu comportamento furtivo. Todas as espécies de cetáceos estão protegidas legalmente, e algumas têm um estatuto de conservação que requer medidas especiais de gestão. Estas medidas requerem, no entanto, conhecimentos de base sobre abundância e distribuição que infelizmente é insuficiente. Para além dos argumentos conservacionistas os cetáceos constituem um recurso económico relevante para o sector do turismo nos Açores. Por esta razão torna-se ainda mais importante o seu estudo: só um bom conhecimento dos padrões de distribuição e de comportamento permitirá garantir uma boa gestão do recurso. […].info:eu-repo/semantics/publishedVersio
Experimental Heat-Bath Cooling of Spins
Algorithmic cooling (AC) is a method to purify quantum systems, such as
ensembles of nuclear spins, or cold atoms in an optical lattice. When applied
to spins, AC produces ensembles of highly polarized spins, which enhance the
signal strength in nuclear magnetic resonance (NMR). According to this cooling
approach, spin-half nuclei in a constant magnetic field are considered as bits,
or more precisely, quantum bits, in a known probability distribution.
Algorithmic steps on these bits are then translated into specially designed NMR
pulse sequences using common NMR quantum computation tools. The
cooling of spins is achieved by alternately combining reversible,
entropy-preserving manipulations (borrowed from data compression algorithms)
with , the transfer of entropy from selected spins to the
environment. In theory, applying algorithmic cooling to sufficiently large spin
systems may produce polarizations far beyond the limits due to conservation of
Shannon entropy.
Here, only selective reset steps are performed, hence we prefer to call this
process "heat-bath" cooling, rather than algorithmic cooling. We experimentally
implement here two consecutive steps of selective reset that transfer entropy
from two selected spins to the environment. We performed such cooling
experiments with commercially-available labeled molecules, on standard
liquid-state NMR spectrometers. Our experiments yielded polarizations that
- , so that the entire
spin-system was cooled. This paper was initially submitted in 2005, first to
Science and then to PNAS, and includes additional results from subsequent years
(e.g. for resubmission in 2007). The Postscriptum includes more details.Comment: 20 pages, 8 figures, replaces quant-ph/051115
Habitat differentiation between groups of Risso's dolphins as evidence of coastal nursery areas
26th Annual Conference of the European Cetacean Society, Galway, Ireland 26-28 March 2012.Previous studies have shown strong site fidelity by Risso's dolphins at a site off Pico Island, Azores. Females with calves tend to be seen together, often with newborn calves. In this study we analyse position and photo-identification data gathered on ocean surveys from 2004 to 2007 to look at the distribution of females with calves of different ages (newborns to 6 months old, 6 months to 2 years and 2 to 4 years) and compare it with pods with no calves present. The association of the different groups with selected ecogeographical variables was tested, and a maximum entropy model was used to create habitat suitability maps, using a 50mx50m grid. The female pods with younger calves were found to have a significantly distinct distribution from those with older calves or without calves. The main difference was that the pods with younger calves tended to be found closer to the shore, whereas the other groups used a wider offshore area. More extensive sampling is required in order to validate the existence and geographical distribution of coastal nursery areas for this species. However, we believe the present data is enough to elicit precautionary conservation measures to reduce human impact on a vulnerable part of the dolphin society, such as that associated with boat traffic, whale watching and swimming with dolphins operations
A Tractable Product Channel Model for Line-of-Sight Scenarios
We present a general and tractable fading model for line-of-sight (LOS)
scenarios, which is based on the product of two independent and non-identically
distributed - shadowed random variables. Simple closed-form
expressions for the probability density function, cumulative distribution
function and moment-generating function are derived, which are as tractable as
the corresponding expressions derived from a product of Nakagami- random
variables. This model simplifies the challenging characterization of LOS
product channels, as well as combinations of LOS channels with non-LOS ones. We
leverage these results to analyze performance measures of interest in the
contexts of wireless powered and backscatter communications, where both forward
and reverse links are inherently of LOS nature, as well as in device-to-device
communications subject to composite fading. In these contexts, the model shows
a higher flexibility when fitting field measurements with respect to
conventional approaches based on product distributions with deterministic LOS,
together with a more complete physical interpretation of the underlying
propagation characteristics.Comment: This work has been submitted to the IEEE for possible publication.
Copyright may be transferred without notice, after which this version may no
longer be accessibl
Cluster state quantum computing in optical fibers
A scheme for the implementation of the cluster state model of quantum
computing in optical fibers, which enables the feedforward feature, is
proposed. This scheme uses the time-bin encoding of qubits. Following
previously suggested methods of applying arbitrary one-qubit gates in optical
fibers, two different ways for the realization of fusion gate types I and II
for cluster production are proposed: a fully time-bin based encoding scheme and
a combination of time-bin and polarization based encoding scheme. Also the
methods of measurement in any desired bases for the purpose of the processing
of cluster state computing for both these encodings are explained.Comment: 6 pages, 11 figures, submitted to the Optical Quantum-Information
Science focus issue of JOSA
Activated Carbon Fiber Monoliths as Supercapacitor Electrodes
Activated carbon fibers (ACF) are interesting candidates for electrodes in electrochemical energy storage devices; however, one major drawback for practical application is their low density. In the present work, monoliths were synthesized from two different ACFs, reaching 3 times higher densities than the original ACFs’ apparent densities. The porosity of the monoliths was only slightly decreased with respect to the pristine ACFs, the employed PVDC binder developing additional porosity upon carbonization. The ACF monoliths are essentially microporous and reach BET surface areas of up to 1838 m2 g−1. SEM analysis reveals that the ACFs are well embedded into the monolith structure and that their length was significantly reduced due to the monolith preparation process. The carbonized monoliths were studied as supercapacitor electrodes in two- and three-electrode cells having 2 M H2SO4 as electrolyte. Maximum capacitances of around 200 F g−1 were reached. The results confirm that the capacitance of the bisulfate anions essentially originates from the double layer, while hydronium cations contribute with a mixture of both, double layer capacitance and pseudocapacitance.Financial support through the projects of reference MAT2014-57687-R, GV/FEDER (PROMETEOII/2014/010), and University of Alicante (VIGROB-136) is gratefully acknowledged
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