Low faunal diversity on Maltese sandy beaches : fact or artefact?

Eight sandy beaches on Malta and two on Gozo were sampled for macrofauna to test the hypothesis that Maltese beaches have an intrinsically low diversity. Stations distributed in the supralittoral (dry zone), mediolittoral (wet zone) and upper infralittoral (submerged zone to 1m water depth) were sampled by sieving core samples and standardised searching during daytime, and pitfall trapping and standardised sweeping of the water column using a hand-net at night, as appropriate. Physical parameters of the sediment were measured and human occupancy of the beaches was estimated. From the supralittoral and mediolittoral, 39 species represented by 1584 individuals were collected by the combined techniques of pitfall trapping, sieving and standard searching. For Ramla beach, which had the highest diversity, 267 individuals representing 25 infaunal species were collected by sieving from a combined volume of 1.175m3 of sand, and 149 individuals representing 28 epifaunal species were collected by standardised searching from a combined area of 700m2 of sand during two winter and two summer sampling sessions between 1992 and 1993. For nine other beaches sampled during the summer of 2000, only six macrofaunal species were collected from core samples, with overall population densities ranging from 4.13 to 45.45 individualsm 2. Only 92 individuals belonging to 12 species were collected by hand-net from the uppermost infralittoral of five beaches sampled using this method during the summer of 2000. Taxa of gastropods, bivalves, decapods, mysids and staphylinid beetles generally abundant on Mediterranean sandy beaches, were entirely absent from the beaches sampled. Few correlations that could explain the impoverishment of Maltese sandy beaches were found between physical parameters and faunal abundances, and other factors such as inadequate sampling effort, human disturbance and marine pollution were also excluded; however, seasonally biased sampling may partly explain the results obtained. One factor that may explain why certain species are missing could be lack of recruitment, due to Malta’s geographical isolation from the European and African mainlands. 2003 Elsevier Ltd. All rights reserved.peer-reviewe

The re-emergence of the B1 cell compartment : is this a pre-lymphoma stage?

Chronic Lymphocytic Leukemia (CLL) are in some cases stereotyped for immunoglobulin variants in different populations, suggesting emergence of B cell subsets following presentation of the same antigen. CLL cells may originate from CD5+ naïve cells and from CD5 memory cells. Gene expression studies characterized a common cell of origin of the two clinical categories of CLL; the unmutated aggressive type and the mutated indolent type. The aim of this study was to investigate the presence of CD5 positive B cells in the elderly and their potential stimulation with exosomes derived from tumor cells. The findings from this study is aimed to create a model to identify instigating carcinomatous factors that may stimulate B1 cells to transform into a CLL-like model. In this study we show that CD19\textsuperscript+ cells (B cells) in cord blood have a high expression of CD5. CD19/CD5 staining of blood samples from senior citizens showed the presence of B cells which also express the CD5 marker, though at a lower expression when compared to CLL cells (CD19+/CD5 dim B cells). Measurement of clonality using λ/Κ flow cytometry staining show a monoclonal origin of the human CD19+/CD5 dim B cells. Monoclonal B cell Lymphocytosis in the elderly is a potential cell compartment that represents the origin of B cell proliferative disorders. The origin of the B cell proliferative disease requires antigen stimulation. A preliminary experiment showed that sorted lymphocytes can be stimulated by exosomes isolated from 2 cancer cells lines, A549 (lung epithelial) and PC3 (prostate cell line). In comparison with phytohaemagglutinin (PHA) and phorbolmyristate acetate (PMA), known lymphocyte stimulators, the exosomes stimulated the proliferation of monocytic-like cells. Further characterization is required to know the origin of these cells. The result shows that one can speculate that exosomes present cancer-derived antigens and stimulate cell proliferation. Further studies are required to evaluate the potential transformation capacity of cancer-derived exosomes. In addition, various cytokines were measured in the sera of senior citizens to investigate a differential release of cytokines in the presence or absence of the CD19+/CD5 dim B cells. Cytokines examined were not significantly different between the 2 groups and further evaluation of cytokine levels is required.peer-reviewe

Adaptividad para problemas de elasticidad lineal en 3D

En este trabajo se presenta un método adaptivo para resolver problemas de elasticidad lineal tridimensional por el método de elementos finitos incluyendo varias experiencias, tanto en la implementación como en la utilización del mismo. La estrategia de densificación está basada en la generación de redes encajadas mediante la subdivisión de elementos tipo simplices. Para la selección de los elementos a dividir se utiliza un indicador elemental de error, equivalente al error en la norma de la energía, el cual también es descrito. Se analizan algunos refinamientos de mallas en presencia de singularidades causadas por esquinas en la frontera del dominio, mostrando el comportamiento de estos estimadores cuando son utilizados en un contexto adaptivo. Finalmente se presentan las conclusiones del proceso adaptivo estudiado.An adaptive scheme to solve three-dimensional elasticity problems by finite elements methods is presented. Some experiences on the implementation and utilization of this process are included. The mesh-enrichment strategy is based on nested mesh generation using simplex subdivision. An elementary error indicator is used for the selection of elements to be divided. This estimator, equivalent to error at the energy norm, is also described. Some mesh refinements due to angles on domain surface is analyzed, showing estimator behavior when used as local error indicator for adaptive refinements. Finally some remarks about this adaptive process are discussed.Peer Reviewe

Banquette faunal assemblages from groomed and ungroomed beaches in the Maltese Islands

The macrofauna associated with beached seagrass wrack on three regularly cleaned (groomed) Maltese beaches and three that are not cleaned (ungroomed) was sampled over a two year period by taking cores and by using pitfall traps. Overall, 40 species were collected from both types of beaches. Coleoptera had the highest species richness (20 species) but the most abundant individual species were the gastropod Truncatella subcylindrica and the amphipod Orchestia stephenseni. Species richness and individual abundance were highest in the winter months for all beaches. The ungroomed beaches had more species (34) than the groomed ones (9) as well as a higher Shannon-Wiener diversity index, Pielou’s evenness, and individual abundance for all species collectively. Thick and long-standing wrack accumulations support higher species richness and abundance and a more taxonomically and trophically diverse biota than thin, freshly deposited layers of wrack.peer-reviewe

Quantitative assessment and physical characterisation of Posidonia oceanica wrack beached along the Maltese coastline

The percentage moisture content, temperature, and percentage organic content (expressed as ash-free dry weight) of wrack, as well as the distribution of leaf lengths at different depths within Posidonia oceanica banquettes stranded along Maltese beaches, was determined. The standing dry weight biomass of wrack beached along the entire Maltese coastline was estimated to be ca. 1,150 metric tons at any one time.peer-reviewe

Adaptividad tridimensional con mallas no estructuradas

En el presente trabajo se muestran algunas experiencias realizadas en el área de adaptatividad para problemas tridimensionales. Basados en problemas de elasticidad, se estudiaron dos formas bien diferenciadas de modificar la discretización, de manera de aumentar el número de grados de libertad en las zonas del dominio que presentan mayor error de discretización. La primera está basada en la idea de división de elementos, mientras que en la segunda se regenera nuevamente la malla. Se describirán brevemente ambas técnicas asimismo como las estrategias adoptadas para redefinir la discretización en base a un indicador del error sobre una solución previamente calculada. Por último se muestran algunos ejemplos de aplicación concretos y se discuten las ventajas y desventajas de ambas metodologías.In this work some experiences on adaptivity for three dimensional problems are presented. Based on a linear elasticity solver, two different approach for the discretization changes are analysed: subdivision of simplexes and remeshing. With the first one, those elements with an estimated error greater than an acceptable value are divided. With the second, the estimated error is used to define a new element size at the centre of each element and a new mesh is generated. Both methods are described and some application examples are presented. Finally the advantage and problems of using these adaptivity techniques are discussed.Peer Reviewe

Considerations on the ecological role of wrack accumulations on sandy beaches in the Maltese Islands and recommendations for their conservation management

Beaches in the Maltese Islands, as in others along the Mediterranean coast, receive copious annual inputs of Posidonia oceanica wrack. A seasonal survey of macrofaunal communities colonising the wrack beached on three groomed and three ungroomed Maltese beaches was made with the principal aim of identifying any significant community differences between the two types of beaches and, consequently, to make recommendations for the conservation management of the wrack resource. Beaches were sampled during the winter and summer of 2002 and 2003 using pitfall traps and coring. The macrofauna collected by coring belonged to fourteen main taxa; Gastropoda and Isopoda were the most represented in terms of individual abundance, and Coleoptera (mainly the families Staphylinidae and Histeridae) were the most species-diverse. Some taxa, such as Staphylinidae, as well as some species, such as the gastropod Truncatella subcylindrica, were only recorded from the wrack on the ungroomed beaches. NMDS ordination and analysis of dominance patterns showed that macrofaunal communities in aged wrack on ungroomed beaches were distinct from those in ‘young’ wrack accumulations on the regularly groomed beaches, with differences being attributed mainly to the conduction of grooming activities or otherwise, rather than to differences in substratum type.peer-reviewe

How Much is Post-Acute Care Use Affected by Its Availability?

To assess the relative impact of clinical factors versus non-clinical factors such as post acute care (PAC) supply - in determining whether patients receive care from skilled nursing facilities (SNFs) or inpatient rehabilitation facilities (IRFs) after discharge from acute care. Medicare acute hospital, IRF and SNF claims provided data on PAC choices; predictors of site of PAC chosen were generated from Medicare claims, provider of services, enrollment file, and Area Resource File data. We used multinomial logit models to predict post-acute care use by elderly patients after hospitalizations for stroke, hip fractures, or lower extremity joint replacements. A file was constructed linking Medicare acute and post-acute utilization data for all sample patients hospitalized in 1999. PAC availability is a more powerful predictor of PAC use than the clinical characteristics in many of our models. The effects of distance to providers and supply of providers are particularly clear in the choice between IRF and SNF care. The farther away the nearest IRF is, and the closer the nearest SNF is, the less likely a patient is to go to an IRF. Similarly, the fewer IRFs, and the more SNFs, there are in the patient's area the less likely the patient is to go to an IRF. In addition, if the hospital from which the patient is discharged has a related IRF or a related SNF the patient is more likely to go there. We find that the availability of PAC is a major determinant of whether patients use such care and which type of PAC facility they use. Further research is needed in order to evaluate whether these findings indicate that a greater supply of PAC leads to both higher use of institutional care and better outcomes or whether it leads to unwarranted expenditures of resources and delays in returning patients to their homes.

Xeroderma Pigmentosum Group C Deficiency Alters Cigarette Smoke DNA Damage Cell Fate and Accelerates Emphysema Development

Cigarette smoke (CS) exposure is a major risk factor for the development of emphysema, a common disease characterized by loss of cells comprising the lung parenchyma. The mechanisms of cell injury leading to emphysema are not completely understood but are thought to involve persistent cytotoxic or mutagenic DNA damage induced by CS. Using complementary cell culture and mouse models of CS exposure, we investigated the role of the DNA repair protein, xeroderma pigmentosum group C (XPC), on CS-induced DNA damage repair and emphysema. Expression of XPC was decreased in mouse lungs after chronic CS exposure and XPC knockdown in cultured human lung epithelial cells decreased their survival after CS exposure due to activation of the intrinsic apoptosis pathway. Similarly, cell autophagy and apoptosis were increased in XPC-deficient mouse lungs and were further increased by CS exposure. XPC deficiency was associated with structural and functional changes characteristic of emphysema, which were worsened by age, similar to levels observed with chronic CS exposure. Taken together, these findings suggest that repair of DNA damage by XPC plays an important and previously unrecognized role in the maintenance of alveolar structures. These findings support that loss of XPC, possibly due to chronic CS exposure, promotes emphysema development and further supports a link between DNA damage, impaired DNA repair, and development of emphysema

Fourier Transform Holography: A Lensless Non-Destructive Imaging Technique

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 - August 2, 201