1,632 research outputs found

    Spatio-temporal variation in the structure of a deep water Posidonia oceanica meadow assessed using non-destructive techniques

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    The Malta-Comino Channel (Maltese islands, central Mediterranean), supports extensive meadows of the seagrass Posidonia oceanica that in some places extend to a depth of around 43 m, which is rare for this seagrass. To assess spatial and temporal variation in the state of the deeper parts of the P. oceanica meadow with time, data on the structural characteristics of the seagrass meadow at its lower bathymetric limit were collected during the summers of 2001, 2003 and 2004 from four stations (two stations within each of two sites) located at a similar depth, over a spatial extent of 500 m. Shoot density was estimated in situ, while data on plant architecture (number of leaves, mean leaf length, and epiphyte load) were successfully obtained using an underwater photographic technique that was specifically designed to avoid destructive sampling of the seagrass. Results indicated that P. oceanica shoot density was lower than that recorded from the same meadow during a study undertaken in 1995; the observed decrease was attributed to the activities of an offshore aquaculture farm that operated during the period 1995–2000 in the vicinity of the meadow. ANOVA indicated significant spatial and temporal variations in meadow structural attributes at both sites during the 3-year study; for example, shoot density values increased overall with time at site A; a indication of potential recovery of the meadow following cessation of the aquaculture operations. Lower shoot density values recorded from site B (compared with site A) were attributed to higher epiphyte loads on the seagrass, relative to those at site A. The findings, which include new data on the structural characteristics of P. oceanica occurring at depths >40 m, are discussed with reference to the use of the nondestructive photographic technique to monitor the state of health of deep water seagrass meadows.peer-reviewe

    Baseline marine benthic surveys in the Maltese Islands (Central Mediterranean)

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    Extract from: MEDCOAST 97 : Proceedings of the Third International Conference on the Mediterranean Coastal Environment, Qawra, Malta / E. Ozhan (editor), (1997)During the period 1991 to 1997, extensive baseline studies of the submarine geomorphology, infralittoral habitats, macrobenthic assemblages, and demersal fish fauna, were carried out in 14 different sites around the Maltese Islands, using conventional SCUBA diving techniques. These were made as part of assessments of the environmental impact of existing or proposed projects, or in order to produce an inventory of coastal resources. In total, these surveys covered a sea-bed area of ca. 7.55Km² and a coastline length of ca 24 km, and represent the most extensive biological surveys of the marine environment carried out to date in the Maltese Islands. The results of these surveys have been presented as maps showing the type, location, and spatial extent of these physical and biological features. The Peres & Picard (1964) scheme, as adapted by Pen~s (1967; 1982) was used to classify and characterize the benthic assemblages recorded during the surveys. Our results show that, in tenus of spatial extent, the most important macrobenthic assemblages are the communities of photophilic 'algae on hard substrata, meadows of the sea-grass Posidonia oceanica and communities of bare well-sorted sand. For all these, many subtypes and facies exist, depending on the light intensity, hydrodynamic conditions, microtopography, sediment granulometry and other edaphic factors, and anthropic influences, including pollution. Other assemblages with a limited spatial distribution include meadows of the sea-grass (vmodocea nodosa and of the Lessepsian immigrant Halophila stipu/acea on sandy bottoms, the assemblages of boulder fields which are complexes of photophilic and sciaphilic communities, and those of marine caves. Our maps are supplemented by descriptions of the different habitats and macrobenthjc assemblages, species lists, and semi-quantitative data on percentage cover for the dominant macroalgae, shoot density counts for sea-grass meadows, and population density counts for the main macrofaunal species. These maps and data-sets are intended to be used (i) for assessing the status of habitats, species assemblages, and individual species, around the Maltese Islands in order to recommend appropriate measures for their conservation, including inclusion in red data lists; (ii) for designation of marine protected areas; and (iii) as baselines against which future monitoring studies and surveys can be compared.peer-reviewe

    Towards integrated coastal zone management, with a special emphasis on the Mediterranean Sea: Introduction

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    Evaluation of two street canyon air quality models using data from European cities

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    This paper presents a sensitivity analysis of the Operational Street Pollution Model (OSPM) and an evaluation of OSPM and the Assessing the Environment Of Locations In Urban Streets (AEOLTUS) model. Both models calculate airborne concentrations of exhaust gases emitted by motor vehicles within street canyons. They perform best when the street canyon aspect ratio is 1.0. OSPM and AEOLIUS have been evaluated using data collected over a two-year period (1 994- 95) in Jagtvej, Copenhagen, Denmark. Further evaluation of the models was carried out using data collected in Giittinger Strasse, Hannover (1994) and Schildhom Strasse, Berlin (1995), both in Germany. In all cases, model runs were carried out for carbon monoxide (CO). In the case of OSPM, two sets of newly proposed emission factors were used for the street canyons in Germany. In the calculation of these factors, the urban driving patterns and variations in the composition of the vehicle fleet according to the engine capacity were assumed as the most appropriate for the cases considered. Furthermore, parameters such as engine operating temperature and the use of catalytic converter were taken into account. Scatter plots of modelled against measured CO concentration yielded an average regression coefficient of 0.90 for the street canyons considered. With the newly proposed emission factors for Germany a lower regression coefficient was obtained. From similar scatter plots, the AEOLIUS model gave a regression coefficient of 0.86 for Jagtvej in 1994 and 0.78 for 1995. For Gottinger and Schildhorn Strasse, the regression coefficient obtained was 0.8 1.peer-reviewe

    Clinical and financial consequences of setting up an asthma clinic at St. Luke’s Hospital

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    The effects of setting up an asthma clinic were assessed in an audit study. A comparison was made between the quality and quantity of medication used by patients before and after attending the asthma clinic. The number and severity of exacerbations during a six month period before and a six month period after attending were also assessed. The cost of treatment before and after was also calculated. In 14% of patients, occupational factors, drugs or underlying lung disease were significant contributors to asthma. The number of acute episodes of severe asthma were reduced from 98 to 47, with hospital admissions falling from 26 to 1. Pulmonary function (%FEV1) improved in the group as a whole with the number of patients having their best FEV above 80% improving from 44 to 71. In spite of the expense of high cost drugs and the running costs of the clinic there were substantial savings largely from the reduced number of hospital admissions. The calculated annual cost fell from Lm 22,769 to Lm 10,654.peer-reviewe

    EmoteControl: An interactive system for real-time control of emotional expression in music

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    Several computer systems have been designed for music emotion research that aim to identify how different structural or expressive cues of music influence the emotions conveyed by the music. However, most systems either operate offline by pre-rendering different variations of the music or operate in real-time but focus mostly on structural cues. We present a new interactive system called EmoteControl, which allows users to make changes to both structural and expressive cues (tempo, pitch, dynamics, articulation, brightness, and mode) of music in real-time. The purpose is to allow scholars to probe a variety of cues of emotional expression from non-expert participants who are unable to articulate or perform their expression of music in other ways. The benefits of the interactive system are particularly important in this topic as it offers a massive parameter space of emotion cues and levels for each emotion which is challenging to exhaustively explore without a dynamic system. A brief overview of previous work is given, followed by a detailed explanation of EmoteControl’s interface design and structure. A portable version of the system is also described, and specifications for the music inputted in the system are outlined. Several use-cases of the interface are discussed, and a formal interface evaluation study is reported. Results suggested that the elements controlling the cues were easy to use and understood by the users. The majority of users were satisfied with the way the system allowed them to express different emotions in music and found it a useful tool for research

    integration of an organic rankine cycle and a photovoltaic unit for micro scale chp applications in the residential sector

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    Abstract The purpose of this work is to analyse the performance of a novel system for combined heat and power (CHP) generation in small-scale applications. The system is based on an Organic Rankine Cycle (ORC) fed with biomass and a photovoltaic (PV) unit. The ORC and PV sub-systems operate in parallel to produce the required electrical energy. A preliminary investigation is performed to define the proper size of the photovoltaic unit. Afterwards, the analysis is focused on the hybrid system and a comparison between the two configurations is carried out. This work demonstrates the potential for integrating biomass and solar energy resources: during daylight, solar radiation is significant and the ORC system can be switched off or operated at partial load. Furthermore, the adoption of biomass makes it possible to overcome the intermittency of solar resource, increase the self-consumed electrical energy, and produce thermal energy, thereby saving natural gas for heating purposes

    Determination of serum zinc levels in normal Maltese adults by atomic absorption spectrophotometry

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    The importance of zinc as one of the essential trace elements in the living organisms is becoming increasingly recognised. In the process of carrying out measurements to establish normal reference values for our laboratory, it was noticed that the values being obtained, generally appeared to be higher than those published in the literature where similar techniques had been employed. It is important to gain further understanding of this metal in both health and disease as it appears that zinc is essential to an important variety of metabolic processes in man. We are unable to offer a satisfactory explanation for the difference in serum zinc levels in the two groups reported in this paper. Local water does not appear to have high zinc content and Maltese soil is known to be zinc deficient. It is known however that local farmers use a zinc containing fungicide (Zineb) on a large scale.peer-reviewe

    LDPCA code construction for Slepian-Wolf coding

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    Error correcting codes used for Distributed Source Coding (DSC) generally assume a random distribution of errors. However, in certain DSC applications, prediction of the error distribution is possible and thus this assumption fails, resulting in a sub-optimal performance. This letter considers the construction of rate-adaptive Low-Density Parity-Check (LDPC) codes where the edges of the variable nodes receiving unreliable information are distributed evenly among all the check nodes. Simulation results show that the proposed codes can reduce the gap to the theoretical bounds by up to 56% compared to traditional codes.peer-reviewe
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