291 research outputs found
Unravelling the effects of exploitation on the size–structure of the intertidal topshell Phorcus sauciatus in harvested and non-harvested Atlantic regions
Intertidal molluscs are keystone species often used as biological indicators of human-driven pertur bations. The increasing levels of harvesting pressure on these intertidal grazers, due to the expansion
of human population on coastal areas, is known to affect negatively the exploited populations by
altering population size–structure and decreasing abundances. A comparative study on the effect
of harvest on the size–structure of Phorcus sauciatus populations was conducted according to the
exploitation level, harvested and non-harvested, throughout the intertidal zone of mainland Portugal,
Azores, Madeira, and the Canaries. The comparative analysis of the size–structure of 10,480 individuals
of P. sauciatus showed that the largest individuals were recorded in the Azores and the smallest in
Madeira. In harvested populations, P. sauciatus showed to be under greater harvesting pressure in the
archipelago of Madeira, where the lowest mean size was observed. In the Canaries the harvesting is
regulated whilst in the mainland Portugal the regulation is scarce. The Azores showed no harvesting
pressure. Marine Protected Areas showed individuals with the highest mean sizes supporting their
effectiveness in preserving the size–structure of this species, regardless the ecoregion and thus,
the harvesting pressure. The present results highlight the importance of harvesting regulation of P.
sauciatus in Madeira, as well as the implementation of management measures aiming at the sustainable
exploitation and conservation of this species.info:eu-repo/semantics/publishedVersio
Weight–length relationships of four intertidal mollusc species from the northeastern Atlantic Ocean and their potential for conservation
Weight-length relationships (WLRs) are frequently used for the development of comparative
studies of life history, population dynamics, ecosystem modelling and estimation of the
production and biomass of populations among regions. WLRs provide information about
growth, wellbeing and fitness of a population in a marine environment. WLRs for four
topshells (Phorcus atratus, Phorcus lineatus, Phorcus mariae, Phorcus sauciatus) caught in
North-eastern Atlantic Ocean (Azores, Canaries, Cape Verde, Madeira and Mainland Portugal)
were established and their relative growth was assessed. The results showed that almost all
species exhibited a positive allometric growth. A comparative study on the effect of harvest
in the relative growth of P. sauciatus in the archipelago of Madeira showed that all the
populations from exploited areas exhibited a negative allometric growth in contrast to the
populations from the Marine Protected Areas (MPAs) which were predominantly isometric.
The present results indicate that the conservation measures established in the protected
areas promoted a positive effect in the protected populations and are valuable for
establishing a set of monitoring and management measures aiming at the sustainable
exploitation and conservation of these species. These results are important to demonstrate
the role of MPAs in the conservation of these keystone species in the north eastern Atlantic
Ocean rocky shore ecosystems.info:eu-repo/semantics/publishedVersio
Exercise-induced left septal fascicular block: an expression of severe myocardial ischemia
The electrocardiogram (ECG) criteria for the left septal fascicular block (LSFB) are not universally accepted and many other denominations can be seen in literature: focal septal block, septal focal block, left septal fascicular block, left anterior septal block, septal fascicular conduction disorder of the left branch, left septal Purkinje network block, left septal subdivision block of the left bundle branch, anterior conduction delay, left median hemiblock, left medial subdivision block of the left bundle branch, middle fascicle block, block of the anteromedial division of the left bundle branch of His, and anteromedial divisional block. During exercise stress test, fascicular blocks (left anterior and posterior) seem to indicate severe coronary artery narrowing of left main coronary or proximal left anterior descending artery disease1 and transient exercise-induced left septal fascicular block has been reported a few times2,3.
54-year-old male, with a history of essential arterial systemic hypertension, primary hyperlipidemia and six-month typical chest pain during exercise (Class II – Canadian Cardiovascular Society) underwent an exercise stress test. During the exercise stress test, ECG demonstrated abrupt prominent anterior forces, an increase in R wave amplitude from V1 to V4, extreme left axis deviation and minor ST segment depression in DII, DIII and aVF (Figure 1). The post-exercise period showed progressive return of the QRS axis in both frontal and horizontal planes and the ST depression worsened by 1 mm. Coronary angiogram (Figure 2A) showed a critical proximal left anterior descending artery lesion. An exercise stress test done three months after coronary artery bypass surgery grafting was normal (Figure 2B)
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Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201
Reverse atrial electrical remodeling: A systematic review
Atrial remodeling is a term introduced in 1995 to describe alterations in atrial structure or
function. Atrial electrical remodeling is characterized by a reduction of refractory period and
action potential duration, dispersion in refractoriness, and a reduction in conduction velocity
of impulse propagation. Numerous animal and human studies have demonstrated that atrial
electrical remodeling impairs normal atrial conduction and provides an environment for
ectopic and re-entrant activity, thus creating a substrate for the initiation or maintenance of
atrial fibrillation. Interestingly, atrial electrical remodeling has been shown to be reversible. In
this systematic review, we examine the occurrence of reverse atrial electrical remodeling in
various clinical settings. (Cardiol J 2011; 18, 6: 625–631
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