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The Southern Ocean plays a pivotal role in the control of atmospheric CO2 levels, via both physical and biological sequestration processes. The biological carbon transfer to the ocean interior is tightly coupled to the availability of other elements, especially iron as a trace-limiting nutrient and dissolved silicon as the mineral substrate that allows diatoms to dominate primary production. Importantly, variations in the silicon cycling are large but not well understood. Here we use Si-30 measurements to track seasonal flows of silica to the deep sea, as captured by sediment trap time series, for the three major zones (Antarctic, AZ; Polar Frontal, PFZ; and Sub-Antarctic, SAZ) of the open Southern Ocean. Variations in the exported flux of biogenic silica (BSi) and its Si-30 composition reveal a range of insights, including that (i) the sinking rate of BSi exceeds 200md(-1) in summer in the AZ yet decreases to very low values in winter that allow particles to remain in the water column through to the following spring, (ii) occasional vertical mixing events affect the Si-30 composition of exported BSi in both the SAZ and AZ, and (iii) the Si-30 signature of diatoms is well conserved through the water column despite strong BSi and particulate organic carbon (POC) attenuation at depth and is closely linked to the Si consumption in surface waters. With the strong coupling observed between BSi and POC fluxes in PFZ and AZ, these data provide new constraints for application to biogeochemical models of seasonal controls on production and export.

Background: Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) is a curative treatment option for many patients with Acute Myeloid Leukemia (AML); however, it can lead to complications of Graft-Versus-Host-Disease (GVHD) which can affect the quality of life and overall survival. The aim of this study was to assess the effects of both acute and chronic GVHD on survival rate in patients with AML who received HSCT. Subjects and Methods: In a longitudinal study, 587 patients with AML who underwent bone marrow transplantation in Tehran-Iran between1991 and 2011 were recruited. All patient records were analyzed for the occurrence of adverse events including acute and chronic GVHD and leukemia relapse. Data were analyzed using Log-rank, Kaplan-Meier, Univariate and Multivariate Cox Regression models. Results: The five-year overall survival (OS) was found to be 71.9% (95% CI: 67.40-76.41). Also there was a significant relationship between cGVHD and OS (P=0.001, HR = 0.476, 95%). Hazard of death in these patients was less than those who did not experience an occurrence of cGVHD and aGVHD (HR= 0.629, P= 0.078). A significant relationship between cGVHD and relapse was observed (P< 0.001) indicating that patients who developed cGVHD experienced a better survival rate. A significant relationship was also found between overall survival and aGVHD grade (P< 0.001). Hazard of death (HD) for cGVHD and relapse variables were estimated to be 0.554 and 3.869. Discussion: This study is one of the largest studies (regarding the number of participants) done to date in the Middle East with quite a long duration (20 years). cGVHD appears to have a positive influence on survival rate in patients with AML who received HSCT. It is recommended that further studies investigate the underlying reason or mechanisms behind this.

This paper presents a mechanism-based approach for modelling the thermomechanical behaviour of a Cr-Mo-V steel. A set of unified viscoplastic constitutive equations were employed to model dislocation density, recrystallisation and grain size during deformation. The evolution of dislocation density accounts for the build-up of dislocations due to plastic strain, the static and dynamic recovery and the effect of recrystallisation. Recrystallisation occurs when a critical dislocation density is reached after an incubation time, and grain size becomes smaller after such event. Gleeble compression tests were used to obtain Stress-strain curves and evaluate the microstructural evolution at different temperature and strain rate, and the material constants for the model were determined from the experimental data. Copyright © 2010 MS&T10®.

A common consequence of Notch signalling in Drosophila is the transcriptional activation of seven Enhancer of split [E(spl)] genes, which encode a family of closely related basic-helix-loop-helix transcriptional repressors. Different E(spl) proteins can functionally substitute for each other, hampering loss-of-function genetic analysis and raising the question of whether any specialization exists within the family. We expressed each individual E(spl) gene using the GAL4-UAS system in order to analyse their effect in a number of cell fate decisions taking place in the wing imaginal disk. We focussed on sensory organ precursor determination, wing rein determination and wing pattern formation. All of the E(spl) proteins affect the first two processes in the same way namely they antagonize neural precursor and vein fates. Yet, the efficacy of this antagonism is quite distinct: E(spl)mβ has the strongest vein suppression effect, whereas E(spl)m8 and E(spl)m7 are the most active bristle suppressors. During wing patterning, Notch activity orchestrates a complex sequence of events that define the dorsoventral boundary of the wing. We have discerned two phases within this process based on the sensitivity of N loss-of-function phenotypes to concomitant expression of E(spl) genes, E(spl) proteins are initially involved in repression of the vg quadrant enhancer, whereas later they appear to relay the Notch signal that triggers activation of cut expression. Of the seven proteins, most active in both of these processes. In E(spl) proteins have partially redundant functions, yet they have evolved distinct preferences in implementing different cell fate decisions, which closely match their individual normal expression patterns. 126 2205 2214 Cited By :38

Made available in DSpace on 2022-04-29T08:42:02Z (GMT). No. of bitstreams: 0 Previous issue date: 1980-01-01 Cultivation began in the 1930's but in the 1940's with the market drop, due to the Second World War, the paulista citrus production declined, aggravated by 'tristeza' disease. After 1945 the export market increased and in the 1950's production increased in Bebedouro on many estates due to the emergence of packing-houses. In the 1960's citrus industries (concentrated juice) for export began. Limeira and Bebedouro are the principal producing and exporting centres of citrus products in Brazil. -after English summary Departamento de Geografia e Planejamento do Instrluto de Geocienaas e Cievicias Exatas da UNESP - Campus de Rio Claro.