14,765 research outputs found
Shelf-Ocean material exchange influencing the Atlantic chemical composition off NW Iberian margin since the last glaciation
Rivers are the main conduit of sediment to the shelf. The basin geology, the drainage area and the discharge rate are the major factors that determine their sediment load (Milliman and Syvistski, 1992). Besides suspended particles, dissolved components may also give some information on the eroded crust. Sr isotopes in carbonate shells of biological organisms have been used to study, in the geological record, the influence exerted by the chemical weathering of the continental crust on the seawater composition (Macdougall, 1991).
In this work, Sr isotope ratios obtained in tests of foraminifera representing the last 40 ka are presented and discussed in the scope of the palaeogeographical evolution of NW Iberia.
This work aims to present and discuss the results of Sr isotope analyses (performed, by TIMS, in the Isotope Geology Laboratory of the University of Aveiro) of tests of two species of foraminifera, from nine samples taken along the OMEX core KC 024-19 (181 cm; 42°08’98’’N, 10°29´96’’W, and 2765m), collected in the Galicia Bank area, off Galicia. Taking into account that Sr contained in the carbonate tests is usually considered as preserving the signature of the contemporaneous seawater, one planktonic species (Globigerina bulloides) and one benthic species (Cibicides wuellerstorfi) were selected in order to try to detect Sr isotope variations both through time and between two different levels of the water column.
The core age model, which records the last 40 ka, is based on a combination of oxygen isotope stratigraphy, eight AMS 14C datings and the synchronisation of the last four Heinrich Events in the Iberian Margin sedimentary records.
As a whole, the obtained 87Sr/86Sr ratios vary between 0.709209 and 0.709108, with a mean 2σ error of 0.000025. These values lie within the range of modern marine Sr isotope ratios (0.70910-0.70922), as previously defined using analyses of both seawater and marine carbonates (see compilation by Faure and Mensing, 2005). Despite their small variation, the 87Sr/86Sr ratios obtained in G. bulloides seem to indicate that Sr dissolved in seawater at the KC 024-19 core site became slightly less radiogenic after the Last Glacial Maximum (LGM). This decrease is concomitant with diminishing amounts of the detrital components in the sediments (Fig. 1). Therefore, both the composition of dissolved Sr, as revealed by results on tests of planktonic foraminifera, and the proportions of suspended terrigenous particulate material arriving at the KC 024-19 site point to a decreasing importance of the contribution of the erosion of the Iberian Variscan crust since the Last Glacial Maximum and in the Holocene.
The 87Sr/86Sr ratios measured in tests of benthic foraminifera (C. wuellerstorfi) are more erratic and no correlation can be established with palaeogeographical/palaeoclimatic constraints. The difference between the behaviour of Sr compositions in G. bulloides and C. wuellerstorfi may indicate that whilst the planktonic foraminifera should reproduce very closely the seawater composition, the benthic organisms should, in addition to the major role of seawater, also be affected by some sort of interaction with the sediments. As such, planktonic foraminifera are probably more reliable indicators of seawater composition in studies involving very small periods and corresponding very slight variations of the 87Sr/86Sr ratios.
Taking into account that G. bulloides is a common planktonic species (living mostly in the first 50m of the water column), whose tests seem to be in equilibrium with sea water composition, variations in its 87Sr/86Sr ratios can be related with changes in the chemical composition of the water of the Atlantic Ocean off NW Iberian Margin.
The highest 87Sr/86Sr values are contemporaneous with a period of low sea level (about -140 m; Dias et al., 2000) during the LGM. According to Dias et al. (2000) at 18 ka BP the shoreline was close to the shelf break. The summital parts of the Gerês and Estrela mountains were covered by local glaciers and close to the coast freezing occurred frequently. The river catchments, which extended far to the shelf, received more rainfall due to a longer, compared to present day conditions, wet season, which promoted both physical and chemical weathering. Higher pluviosity combined with the effect of spring ice melting maintained high river discharge and consequently caused very important sediment supply to the coastal zone. The extremely narrow shelf was a very energetic environment due to sea bottom inclination and very limited long wave refraction. Therefore, at that time, a long wet season and very competent rivers should have caused important erosion of the Variscan basement in NW Iberia. Additionally, then, the shoreline was much closer to the KC 024-19 site. The combination of all these factors favoured an important deposition of terrigenous sediments and the local slight enrichment in radiogenic Sr of the seawater.
With sea level rise, after the deglaciation and during the Holocene, the river estuaries became progressively far away from the shelf break. Their competence of transport also became progressively reduced and the offshore transport of detrital sediments became progressively lower. Conversely the biogenic carbonate proportion in the sediments increased, due to lower dilution by the terrigenous particles. Simultaneously, the values of 87Sr/86Sr in the seawater at the KC 024-19 site became lower, as a consequence of a complete homogenization with the ocean global composition, which was now more effective with the increasing distance towards shoreline
Non-Gaussian velocity distributions - The effect on virial mass estimates of galaxy groups
We present a study of 9 galaxy groups with evidence for non-Gaussianity in
their velocity distributions out to 4R200. This sample is taken from 57 groups
selected from the 2PIGG catalog of galaxy groups. Statistical analysis
indicates that non-Gaussian groups have masses significantly higher than
Gaussian groups. We also have found that all non-Gaussian systems seem to be
composed of multiple velocity modes. Besides, our results indicate that
multimodal groups should be considered as a set of individual units with their
own properties. In particular, we have found that the mass distribution of such
units are similar to that of Gaussian groups. Our results reinforce the idea of
non-Gaussian systems as complex structures in the phase space, likely
corresponding to secondary infall aggregations at a stage before virialization.
The understanding of these objects is relevant for cosmological studies using
groups and clusters through the mass function evolution.Comment: 5 pages, 4 figures and 2 tables. Accepted for publication in the
MNRA
AUTOMATED COLLECTION OF QUALITY-OF-LIFE DATA: TOUCH-SCREEN COMPUTER SYSTEMS IN PATIENTS WITH IMMUNE DISEASES
AUTOMATED COLLECTION OF QUALITY-OF-LIFE DATA: TOUCH-SCREEN COMPUTER SYSTEMS IN PATIENTS WITH IMMUNE DISEASES
Claúdia Ribeiro1,2,3, Augusta Silveira4,3, Isabel Silva4, Catarina Ribeiro4, Carlos Vasconcelos2,3
1UCP, 2HSA/CHP, 3ICBAS/UP, 4UFP e 5HSMF.
Universidade Católica Portuguesa (UCP), Porto.
Hospital de Santo António, Centro Hospitalar do Porto (HSA/CHP), Porto.
Instituto Ciências Biomédicas Abel Salazar, Universidade do Porto (ICBAS/UP), Porto.
Universidade Fernando Pessoa (UFP), Porto.
Hospital Santa Maria da Feira (HSMF), Porto.
Background
The increase of technological knowledge and methodology has allowed the practice of redirecting epidemiological research, particularly in the field of chronic disease. Although capable of controlling the accumulation of events and constraints imposed by the treatment can lead to a drastic change in quality of life (QoL) of subjects progressed to varying degrees of disability and death. In this perspective the Quality of Life Related to Health (HRQOL) has taken a leading role and its evaluation is indispensable in Medicine.
Aim
The aims of this study were (1) analyze the importance of HRQOL assessment as a tool for health promotion and a way of measuring the effectiveness of interventions in daily practice in patients with coexisting chronic immune system (PCSI), (2) evaluation of alternative methods for the automated collection of data on HRQOL and development of an electronic interface in sample of 320 patients, (3) creating a database to ascertain the epidemiological profile of PCSI, and identification of socio-economic, demographic and clinical data of these individuals, (4) using the QoL indicator as a predictor in decision treatment and use the preferences of patients.
Methods
A total of 473 patients with chronic diseases of the immune system, which were applied Graffar Index, SF-36v2, a demographic questionnaire and identification of clinical variables.
Results
The results of this investigation suggest that the demographic, socio-economic and clinics are associated with significant differences in QoL cumulative and chronic complications associated with different pathologies. The results verified the existence of significant correlations between the different diagnoses, duration of disease and therapy. In general, patients who have chronic diseases of the immune system such as rheumatoid arthritis, lupus, scleroderma, Bechet's disease, Sjögren's syndrome or infection with human immunodeficiency virus 1 or 2 showed a worse QoL than the general population. The derivations of preferences from the SF-36v2 exhibit strong correlations with the preferences measured with the SF-6D.
Conclusions
This suggests that both the application of the SF-36v2 as the SF-6D can be important sources of preferences to implement measures in economic evaluation in healthcare. HRQL can and should be integrated into immune clinical practice. The translation of graphical results given to the clinician at the beginning of the consultation, favors the rapid analysis of global values of the patient's HRQL. This assessment can be an excellent diagnostic tool to be used routinely in clinical practice or assisting in disease management and therapeutic decision making.
Apresentador:
Cláudia Ribeiro, Médica Dentista. Doutoranda, Faculdade de Medicina da Universidade de Santiago de Compostela
AUTOMATED COLLECTION OF QUALITY-OF-LIFE DATA: TOUCH-SCREEN COMPUTER SYSTEMS IN PATIENTS WITH IMMUNE DISEASES
AUTOMATED COLLECTION OF QUALITY-OF-LIFE DATA: TOUCH-SCREEN COMPUTER SYSTEMS IN PATIENTS WITH IMMUNE DISEASES
Claúdia Ribeiro1,2,3, Augusta Silveira4,3, Isabel Silva4, Catarina Ribeiro4, Carlos Vasconcelos2,3
1UCP, 2HSA/CHP, 3ICBAS/UP, 4UFP e 5HSMF.
Universidade Católica Portuguesa (UCP), Porto.
Hospital de Santo António, Centro Hospitalar do Porto (HSA/CHP), Porto.
Instituto Ciências Biomédicas Abel Salazar, Universidade do Porto (ICBAS/UP), Porto.
Universidade Fernando Pessoa (UFP), Porto.
Hospital Santa Maria da Feira (HSMF), Porto.
Background
The increase of technological knowledge and methodology has allowed the practice of redirecting epidemiological research, particularly in the field of chronic disease. Although capable of controlling the accumulation of events and constraints imposed by the treatment can lead to a drastic change in quality of life (QoL) of subjects progressed to varying degrees of disability and death. In this perspective the Quality of Life Related to Health (HRQOL) has taken a leading role and its evaluation is indispensable in Medicine.
Aim
The aims of this study were (1) analyze the importance of HRQOL assessment as a tool for health promotion and a way of measuring the effectiveness of interventions in daily practice in patients with coexisting chronic immune system (PCSI), (2) evaluation of alternative methods for the automated collection of data on HRQOL and development of an electronic interface in sample of 320 patients, (3) creating a database to ascertain the epidemiological profile of PCSI, and identification of socio-economic, demographic and clinical data of these individuals, (4) using the QoL indicator as a predictor in decision treatment and use the preferences of patients.
Methods
A total of 473 patients with chronic diseases of the immune system, which were applied Graffar Index, SF-36v2, a demographic questionnaire and identification of clinical variables.
Results
The results of this investigation suggest that the demographic, socio-economic and clinics are associated with significant differences in QoL cumulative and chronic complications associated with different pathologies. The results verified the existence of significant correlations between the different diagnoses, duration of disease and therapy. In general, patients who have chronic diseases of the immune system such as rheumatoid arthritis, lupus, scleroderma, Bechet's disease, Sjögren's syndrome or infection with human immunodeficiency virus 1 or 2 showed a worse QoL than the general population. The derivations of preferences from the SF-36v2 exhibit strong correlations with the preferences measured with the SF-6D.
Conclusions
This suggests that both the application of the SF-36v2 as the SF-6D can be important sources of preferences to implement measures in economic evaluation in healthcare. HRQL can and should be integrated into immune clinical practice. The translation of graphical results given to the clinician at the beginning of the consultation, favors the rapid analysis of global values of the patient's HRQL. This assessment can be an excellent diagnostic tool to be used routinely in clinical practice or assisting in disease management and therapeutic decision making.
Apresentador:
Cláudia Ribeiro, Médica Dentista. Doutoranda, Faculdade de Medicina da Universidade de Santiago de Compostela
High resolution tsunami modelling for the evaluation of potential risk areas in Setúbal (Portugal)
The use of high resolution hydrodynamic modelling to simulate the potential effects of tsunami events can provide relevant information about the most probable inundation areas. Moreover, the consideration of complementary data such as the type of buildings, location of priority equipment, type of roads, enables mapping of the most vulnerable zones, computing of the expected damage on man-made structures, constrain of the definition of rescue areas and escape routes, adaptation of emergency plans and proper evaluation of the vulnerability associated with different areas and/or equipment. <br><br> Such an approach was used to evaluate the specific risks associated with a potential occurrence of a tsunami event in the region of Setúbal (Portugal), which was one of the areas most seriously affected by the 1755 tsunami. <br><br> In order to perform an evaluation of the hazard associated with the occurrence of a similar event, high resolution wave propagation simulations were performed considering different potential earthquake sources with different magnitudes. Based on these simulations, detailed inundation maps associated with the different events were produced. These results were combined with the available information on the vulnerability of the local infrastructures (building types, roads and streets characteristics, priority buildings) in order to impose restrictions in the production of high-scale potential damage maps, escape routes and emergency routes maps
- …