649 research outputs found
Distribution of throughfall and stemflow in agroforestry, perennial monoculture, fallow and primary forest in the central Amazon, Brazil.
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Position of Aleutian Low Drives Dramatic Inter-Annual Variability in Atmospheric Transport of Glacial Iron to the Gulf of Alaska
Our understanding of glacial flour dust storm delivery of iron to the Gulf of Alaska (GoA) is limited. We interpret concurrent time-series satellite, meteorological, and aerosol geochemical data from the GoA to examine how inter-annual variability in regional weather patterns impacts offshore aerosol glacial iron transport. In 2011, when a northerly Aleutian Low (AL) was persistent during fall, dust emission was suppressed and highly intermittent due to prevalent wet conditions, low winds and a deep early season snowpack. Conversely, in 2012, frequent and prolonged fall dust storms and high offshore glacial iron transport were driven by dry conditions and strong offshore winds generated by persistent strong high pressure over the Alaskan interior and Bering Sea and a southerly AL. Remarkable inter-annual variability in offshore glacial aerosol iron transport indicates that the role of glacial dust in GoA nutrient cycles is likely highly dynamic and particularly sensitive to regional climate forcing
High‐Frequency Dissolved Organic Carbon and Nitrate Measurements Reveal Differences in Storm Hysteresis and Loading in Relation to Land Cover and Seasonality
Storm events dominate riverine loads of dissolved organic carbon (DOC) and nitrate and are expected to increase in frequency and intensity in many regions due to climate change. We deployed three high‐frequency (15 min) in situ absorbance spectrophotometers to monitor DOC and nitrate concentration for 126 storms in three watersheds with agricultural, urban, and forested land use/land cover. We examined intrastorm hysteresis and the influences of seasonality, storm size, and dominant land use/land cover on storm DOC and nitrate loads. DOC hysteresis was generally anticlockwise at all sites, indicating distal and plentiful sources for all three streams despite varied DOC character and sources. Nitrate hysteresis was generally clockwise for urban and forested sites, but anticlockwise for the agricultural site, indicating an exhaustible, proximal source of nitrate in the urban and forested sites, and more distal and plentiful sources of nitrate in the agricultural site. The agricultural site had significantly higher storm nitrate yield per water yield and higher storm DOC yield per water yield than the urban or forested sites. Seasonal effects were important for storm nitrate yield in all three watersheds and farm management practices likely caused complex interactions with seasonality at the agricultural site. Hysteresis indices did not improve predictions of storm nitrate yields at any site. We discuss key lessons from using high‐frequency in situ optical sensors
Theobroma grandiflorum (Willd. ex Spreng.) Schum: production factors in agro-ecosystems.
Study to evaluate the feasibiligy of sustainable agroforestry in central Amazonia (Brasil), paying special attention to the potential to recultivate degraded areas. For this purpose differente mixed cultivationsystems are being tested and compared to monocultures designed according to common practices. Study groups of various SHIFT-Projects are working on this experimental site, each groupe dealing with particular aspects of the different agro-ecosystems
Relationships between CYP2D6 phenotype, breast cancer and hot flushes in women at high risk of breast cancer receiving prophylactic tamoxifen: results from the IBIS-I trial
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Tailoring Adjuvant Endocrine Therapy for Postmenopausal Breast Cancer: A CYP2D6 Multiple-Genotype-Based Modeling Analysis and Validation
Purpose: Previous studies have suggested that postmenopausal women with breast cancer who present with wild-type CYP2D6 may actually have similar or superior recurrence-free survival outcomes when given tamoxifen in place of aromatase inhibitors (AIs). The present study established a CYP2D6 multiple-genotype-based model to determine the optimal endocrine therapy for patients harboring wild-type CYP2D6. Methods: We created a Markov model to determine whether tamoxifen or AIs maximized 5-year disease-free survival (DFS) for extensive metabolizer (EM) patients using annual hazard ratio (HR) data from the BIG 1-98 trial. We then replicated the model by evaluating 9-year event-free survival (EFS) using HR data from the ATAC trial. In addition, we employed two-way sensitivity analyses to explore the impact of HR of decreased-metabolizer (DM) and its frequency on survival by studying a range of estimates. Results: The 5-year DFS of tamoxifen-treated EM patients was 83.3%, which is similar to that of genotypically unselected patients who received an AI (83.7%). In the validation study, we further demonstrated that the 9-year EFS of tamoxifentreated EM patients was 81.4%, which is higher than that of genotypically unselected patients receiving tamoxifen (78.4%) and similar to that of patients receiving an AI (83.2%). Two-way sensitivity analyses demonstrated the robustness of the results
Mashups: An Approach to Overcoming the Business/IT Gap in Service-Oriented Architectures
For quite a long time already, great importance has been attached to the concept of Service-Oriented Architectures for future IT-architectures. However, a major challenge in implementing this concept lies in the gap between the functional department and IT department. Mashups, an architecture also based on services, try to avoid this gap by letting the user himself integrate the services. The following article analyzes similarities and differences between both architecture approaches, and explains to what extent and in which cases Mashups could complement a Service-Oriented Architecture
Obesity Alters Endoxifen Plasma Levels in Young Breast Cancer Patients: A Pharmacometric Simulation Approach
Endoxifen is the most important metabolite of the prodrug tamoxifen. High interindividual variability in endoxifen steady-state concentrations (CSS,min ENDX) is observed under tamoxifen standard dosing breast cancer patients that do not reach endoxifen concentrations above a proposed therapeutic threshold of 5.97 ng/mL may be at higher recurrence risk. In this investigation, 10 clinical tamoxifen studies were pooled (nPatients=1388) to investigate influential factors on CSS,min ENDX using nonlinear mixed-effects modelling. Age and body weight were found to significantly impact CSS,min ENDX in addition to CYP2D6 phenotype. Compared to post-menopausal patients, pre-menopausal patients had a 30% higher risk for subtarget CSS,min ENDX at tamoxifen 20 mg per day. In treatment simulations for distinct patient subpopulations, young overweight patients had a 3.1-13.8-fold higher risk for subtarget CSS,min ENDX compared to elderly low-weight patients. Considering ever-rising obesity rates and the clinical importance of tamoxifen for pre-menopausal patients, this subpopulation may benefit most from individualised tamoxifen dosing
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Ubiquitous Presence of Fe(II) in Aquatic Colloids and Its Association with Organic Carbon
Despite being thermodynamically less stable, small ferrous colloids (60 nm to 3 μm in diameter) remain an important component of the biogeochemical cycle at the Earth’s surface, yet their composition and structure and the reasons for their persistence are still poorly understood. Here we use X-ray-based Fe L-edge and carbon K-edge spectromicroscopy to address the speciation and organic–mineral associations of ferrous, ferric, and Fe-poor particles collected from sampling sites in both marine and freshwater environments. We show that Fe(II)-rich phases are prevalent throughout different aquatic regimes yet exhibit a high degree of chemical heterogeneity. Furthermore, we show that Fe-rich particles show strong associations with organic carbon. The observed association of Fe(II) particles with carboxamide functional groups suggests a possible microbial role in the preservation of Fe(II). These finding have significant implications for the behavior of Fe(II) colloids in oxygenated waters, and their role in different aquatic biogeochemical processes
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