958 resultados para Transport data


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Abstract Cloud computing service emerged as an essential component of the Enterprise {IT} infrastructure. Migration towards a full range and large-scale convergence of Cloud and network services has become the current trend for addressing requirements of the Cloud environment. Our approach takes the infrastructure as a service paradigm to build converged virtual infrastructures, which allow offering tailored performance and enable multi-tenancy over a common physical infrastructure. Thanks to virtualization, new exploitation activities of the physical infrastructures may arise for both transport network and Data Centres services. This approach makes network and Data Centres’ resources dedicated to Cloud Computing to converge on the same flexible and scalable level. The work presented here is based on the automation of the virtual infrastructure provisioning service. On top of the virtual infrastructures, a coordinated operation and control of the different resources is performed with the objective of automatically tailoring connectivity services to the Cloud service dynamics. Furthermore, in order to support elasticity of the Cloud services through the optical network, dynamic re-planning features have been provided to the virtual infrastructure service, which allows scaling up or down existing virtual infrastructures to optimize resource utilisation and dynamically adapt to users’ demands. Thus, the dynamic re-planning of the service becomes key component for the coordination of Cloud and optical network resource in an optimal way in terms of resource utilisation. The presented work is complemented with a use case of the virtual infrastructure service being adopted in a distributed Enterprise Information System, that scales up and down as a function of the application requests.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The regular arrangement of leaves around a plant's stem, called phyllotaxis, has for centuries attracted the attention of philosophers, mathematicians and natural scientists; however, to date, studies of phyllotaxis have been largely theoretical. Leaves and flowers are formed from the shoot apical meristem, triggered by the plant hormone auxin. Auxin is transported through plant tissues by specific cellular influx and efflux carrier proteins. Here we show that proteins involved in auxin transport regulate phyllotaxis. Our data indicate that auxin is transported upwards into the meristem through the epidermis and the outermost meristem cell layer. Existing leaf primordia act as sinks, redistributing auxin and creating its heterogeneous distribution in the meristem. Auxin accumulation occurs only at certain minimal distances from existing primordia, defining the position of future primordia. This model for phyllotaxis accounts for its reiterative nature, as well as its regularity and stability.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

OBJECTIVE To determine plasma and urine concentrations of retinol, retinyl esters, retinol-binding protein (RBP), and Tamm-Horsfall protein (THP) in dogs with chronic renal disease (CRD). ANIMALS 17 dogs with naturally developing CRD and 21 healthy control dogs. PROCEDURE A diagnosis of CRD was established on the basis of clinical signs, plasma concentrations of creatinine and urea, and results of urinalysis. Concentrations of retinol and retinyl esters were measured by use of reverse-phase high-performance liquid chromatography. Concentrations of RBP and THP were measured by use of sensitive ELISA systems. RESULTS Dogs with CRD had higher plasma concentrations of retinol, which were not paralleled by differences in plasma concentrations of RBP. Calculated ratio of urinary total vitamin A (sum of concentrations of retinol and retinyl esters to creatinine concentration) and ratio of the concentration of urinary retinyl esters to creatinine concentration did not differ between groups. However, we detected a significantly higher retinol-to-creatinine ratio in the urine of dogs with CRD, which was paralleled by a higher urinary RBP-to-creatinine ratio. Thus, in dogs with CRD, the estimated fractional clearance of total vitamin A, retinol, and RBP was increased. Furthermore, dogs with CRD had a reduced urinary THP-to-creatinine ratio. CONCLUSIONS AND CLINICAL RELEVANCE Results of this study documented that CRD affects the concentrations of retinol in plasma and urine of dogs. Analysis of the data indicates that measurement of urinary RBP and urinary THP concentrations provides valuable information that can be helpful in follow-up monitoring of dogs with CRD.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

BPAG1a and BPAG1b (BPAG1a/b) constitute two major isoforms encoded by the dystonin (Dst) gene and show homology with MACF1a and MACF1b. These proteins are members of the plakin family, giant multi-modular proteins able to connect the intermediate filament, microtubule and microfilament cytoskeletal networks with each other and to distinct cell membrane sites. They also serve as scaffolds for signaling proteins that modulate cytoskeletal dynamics. To gain better insights into the functions of BPAG1a/b, we further characterized their C-terminal region important for their interaction with microtubules and assessed the role of these isoforms in the cytoskeletal organization of C2.7 myoblast cells. Our results show that alternative splicing does not only occur at the 5' end of Dst and Macf1 pre-mRNAs, as previously reported, but also at their 3' end, resulting in expression of additional four mRNA variants of BPAG1 and MACF1. These isoform-specific C-tails were able to bundle microtubules and bound to both EB1 and EB3, two microtubule plus end proteins. In the C2.7 cell line, knockdown of BPAG1a/b had no major effect on the organization of the microtubule and microfilament networks, but negatively affected endocytosis and maintenance of the Golgi apparatus structure, which became dispersed. Finally, knockdown of BPAG1a/b caused a specific decrease in the directness of cell migration, but did not impair initial cell adhesion. These data provide novel insights into the complexity of alternative splicing of Dst pre-mRNAs and into the role of BPAG1a/b in vesicular transport, Golgi apparatus structure as well as in migration in C2.7 myoblasts.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

A new technique to porewater extraction from claystone employs advective displacement of the in situ porewater by traced artificial porewater. Monitoring of tracer breakthrough yields species-specific transport properties. Results for Opalinus Clay from the Mont Terri Research Laboratory indicate that the chemical disturbances due to the method are minimal, and the observed significant differences in transport properties for Br– and 2H are in agreement with existing data. Sampling times are 2–4 months, and observation of tracer breakthrough takes 12–24 months at hydraulic conductivity of ∼10-13 m/s.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The spatial distributions of non-reactive natural tracers (anions, stable water isotopes, noble gases) in pore water of clay-rich formations were studied at nine sites. Regular curved profiles were identified in most cases. Transport modeling considering diffusion, advection and available constraints on the paleo-hydrogeological evolution indicates generally that diffusion alone can explain the observations, whereas a marked advective component would distort the profiles and so is not consistent with the data.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Air was sampled from the porous firn layer at the NEEM site in Northern Greenland. We use an ensemble of ten reference tracers of known atmospheric history to characterise the transport properties of the site. By analysing uncertainties in both data and the reference gas atmospheric histories, we can objectively assign weights to each of the gases used for the depth-diffusivity reconstruction. We define an objective root mean square criterion that is minimised in the model tuning procedure. Each tracer constrains the firn profile differently through its unique atmospheric history and free air diffusivity, making our multiple-tracer characterisation method a clear improvement over the commonly used single-tracer tuning. Six firn air transport models are tuned to the NEEM site; all models successfully reproduce the data within a 1σ Gaussian distribution. A comparison between two replicate boreholes drilled 64 m apart shows differences in measured mixing ratio profiles that exceed the experimental error. We find evidence that diffusivity does not vanish completely in the lock-in zone, as is commonly assumed. The ice age- gas age difference (1 age) at the firn-ice transition is calculated to be 182+3−9 yr. We further present the first intercomparison study of firn air models, where we introduce diagnostic scenarios designed to probe specific aspects of the model physics. Our results show that there are major differences in the way the models handle advective transport. Furthermore, diffusive fractionation of isotopes in the firn is poorly constrained by the models, which has consequences for attempts to reconstruct the isotopic composition of trace gases back in time using firn air and ice core records.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Trauma and severe head injuries are important issues because they are prevalent, because they occur predominantly in the young, and because variations in clinical management may matter. Trauma is the leading cause of death for those under age 40. The focus of this head injury study is to determine if variations in time from the scene of accident to a trauma center hospital makes a difference in patient outcomes.^ A trauma registry is maintained in the Houston-Galveston area and includes all patients admitted to any one of three trauma center hospitals with mild or severe head injuries. A study cohort, derived from the Registry, includes 254 severe head injury cases, for 1980, with a Glasgow Coma Score of 8 or less.^ Multiple influences relate to patient outcomes from severe head injury. Two primary variables and four confounding variables are identified, including time to emergency room, time to intubation, patient age, severity of injury, type of injury and mode of transport to the emergency room. Regression analysis, analysis of variance, and chi-square analysis were the principal statistical methods utilized.^ Analysis indicates that within an urban setting, with a four-hour time span, variations in time to emergency room do not provide any strong influence or predictive value to patient outcome. However, data are suggestive that at longer time periods there is a negative influence on outcomes. Age is influential only when the older group (55-64) is included. Mode of transport (helicopter or ambulance) did not indicate any significant difference in outcome.^ In a multivariate regression model, outcomes are influenced primarily by severity of injury and age which explain 36% (R('2)) of variance. Inclusion of time to emergency room, time to intubation, transport mode and type injury add only 4% (R('2)) additional contribution to explaining variation in patient outcome.^ The research concludes that since the group most at risk to head trauma is the young adult male involved in automobile/motorcycle accidents, more may be gained by modifying driving habits and other preventive measures. Continuous clinical and evaluative research are required to provide updated clinical wisdom in patient management and trauma treatment protocols. A National Institute of Trauma may be required to develop a national public policy and evaluate the many medical, behavioral and social changes required to cope with the country's number 3 killer and the primary killer of young adults.^

Relevância:

30.00% 30.00%

Publicador:

Resumo:

We examined near-surface, late Holocene deep-sea sediments at nine sites on a north-south transect from the Congo Fan (4°S) to the Cape Basin (30°S) along the Southwest African continental margin. Contents, distribution patterns and molecular stable carbon isotope signatures of long-chain n-alkanes (C27-C33) and n-alkanols (C22-C32) are indicators of land plant vegetation of different biosynthetic types, which can be correlated with concentrations and distributions of pollen taxa in the same sediments. Calculated clusters of wind trajectories and satellite Aerosol Index imagery afford information on the source areas for the lipids and pollen on land and their transport pathways to the ocean sites. This multidisciplinary approach on an almost continental scale provides clear evidence of latitudinal differences in lipid and pollen composition paralleling the major phytogeographic zonations on the adjacent continent. Dust and smoke aerosols are mainly derived from the western and central South African hinterland dominated by deserts, semi-deserts and savannah regions rich in C4 and CAM plants. The northern sites (Congo Fan area and northern Angola Basin), which get most of their terrestrial material from the Congo Basin and the Angolan highlands, may also receive some material from the Chad region. Very little aerosol from the African continent is transported to the most southerly sites in the Cape Basin. As can be expected from the present position of the phytogeographic zones, the carbon isotopic signatures of the n-alkanes and n-alkanols both become isotopically more enriched in 13C from north to south. The results of the study suggest that this combination of pollen data and compound-specific isotope geochemical proxies can be effectively applied in the reconstruction of past continental phytogeographic developments.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The Greenland ice sheet is accepted as a key factor controlling the Quaternary glacial scenario. However, the origin and mechanisms of major Arctic glaciation starting at 3.15 Ma and culminating at 2.74 Ma are still controversial. For this phase of intense cooling Ravelo et al. proposed a complex gradual forcing mechanism. In contrast, our new submillennial-scale paleoceanographic records from the Pliocene North Atlantic suggest a far more precise timing and forcing for the initiation of northern hemisphere glaciation (NHG), since it was linked to a 2-3 °C surface water warming during warm stages from 2.95 to 2.82 Ma. These records support previous models, claiming that the final closure of the Panama Isthmus (3.0- ~2.5 Ma induced an increased poleward salt and heat transport. Associated strengthening of North Atlantic Thermohaline Circulation and in turn, an intensified moisture supply to northern high latitudes resulted in the build-up of NHG, finally culminating in the great, irreversible climate crash at marine isotope stage G6 (2.74 Ma). In summary, there was a two-step threshold mechanism that marked the onset of NHG with glacial-to-interglacial cycles quasi-persistent until today.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In locations of rapid sediment accumulation receiving substantial amounts of laterally transported material the timescales of transport and accurate quantification of the transported material are at the focus of intense research. Here we present radiocarbon data obtained on co-occurring planktic foraminifera, marine haptophyte biomarkers (alkenones) and total organic carbon (TOC) coupled with excess Thorium-230 (230Thxs) measurements on four sediment cores retrieved in 1649-2879 m water depth from two such high accumulation drift deposits in the Northeast Atlantic, Björn and Gardar Drifts. While 230Thxs inventories imply strong sediment focussing, no age offsets are observed between planktic foraminifera and alkenones, suggesting that redistribution of sediments is rapid and occurs soon after formation of marine organic matter, or that transported material contains negligible amounts of alkenones. An isotopic mass balance calculation based on radiocarbon concentrations of co-occurring sediment components leads us to estimate that transported sediment components contain up to 12% of fossil organic matter that is free of or very poor in alkenones, but nevertheless appears to consist of a mixture of fresh and eroded fossil material. Considering all available constraints to characterize transported material, our results show that although focussing factors calculated from bulk sediment 230Thxs inventories may allow useful approximations of bulk redeposition, they do not provide a unique estimate of the amount of each laterally transported sediment component. Furthermore, our findings provide evidence that the occurrence of lateral sediment redistribution alone does not always hinder the use of multiple proxies but that individual sediment fractions are affected to variable extents by sediment focussing.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

ODP Site 1124, located 600 km east of the North Island of New Zealand, records post-middle Oligocene variations in the Pacific Deep Western Boundary Current (DWBC) and New Zealand's climatic and tectonic evolution. Sediment parameters, such as terrigenous grain size, flux, magnetic fabric, and non-depositional episodes, are used to interpret DWBC intensity and Antarctic climate. Interpretations of DWBC velocities indicate that the Antarctic Circumpolar Current reached modern intensities at ~23 Ma, as the tectonic seaways expanded, completing the thermal isolation of Antarctica. Periods of more intense bottom water formation are suggested by the presence of hiatuses formed under the DWBC at 22.5-17.6, 16.5-15, and 14-11 Ma. The oldest interval of high current intensity occurs within a climatically warm period during which the intensity of thermohaline circulation around Antarctica increased as a result of recent opening of circum-Antarctic gateways. The younger hiatuses represent glacial periods on Antarctica and major fluctuations in the East Antarctic Ice Sheet, whereas intervals around the hiatuses represent times of relative warmth, but with continued current activity. The period between 11 to 9 Ma is characterized by conditions surrounding a high velocity DWBC around the time of the formation and stabilization of the West Antarctic Ice Sheet. The increased terrigenous input may result from either changing Antarctic conditions or more direct sediment transport from New Zealand. The Pacific DWBC did not exert a major influence on sedimentation at Site 1124 from 9 Ma to the present; the late Miocene to Pleistocene sequence is more influenced by the climatic and tectonic history of New Zealand. Despite the apparent potential for increased sediment supply to this site from changes in sediment channeling, increasing rates of mountain uplift, and volcanic activity, terrigenous fluxes remain low and constant throughout this younger period.