2,721 research outputs found
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Combined use of satellite estimates and rain gauge observations to generate highâquality historical rainfall time series over Ethiopia
Climate data are used in a number of applications including climate risk management and adaptation to climate change. However, the availability of climate data, particularly throughout rural Africa, is very limited. Available weather stations are unevenly distributed and mainly located along main roads in cities and towns. This imposes severe limitations to the availability of climate information and services for the rural community where, arguably, these services are needed most. Weather station data also suffer from gaps in the time series. Satellite proxies, particularly satellite rainfall estimate, have been used as alternatives because of their availability even over remote parts of the world. However, satellite rainfall estimates also suffer from a number of critical shortcomings that include heterogeneous time series, short time period of observation, and poor accuracy particularly at higher temporal and spatial resolutions. An attempt is made here to alleviate these problems by combining station measurements with the complete spatial coverage of satellite rainfall estimates. Rain gauge observations are merged with a locally calibrated version of the TAMSAT satellite rainfall estimates to produce over 30-years (1983-todate) of rainfall estimates over Ethiopia at a spatial resolution of 10 km and a ten-daily time scale. This involves quality control of rain gauge data, generating locally calibrated version of the TAMSAT rainfall estimates, and combining these with rain gauge observations from national station network. The infrared-only satellite rainfall estimates produced using a relatively simple TAMSAT algorithm performed as good as or even better than other satellite rainfall products that use passive microwave inputs and more sophisticated algorithms. There is no substantial difference between the gridded-gauge and combined gauge-satellite products over the test area in Ethiopia having a dense station network; however, the combined product exhibits better quality over parts of the country where stations are sparsely distributed
Remnants of an ancient forest provide ecological context for Early Miocene fossil apes
The lineage of apes and humans (Hominoidea) evolved and radiated across Afro-Arabia in the early Neogene during a time of global climatic changes and ongoing tectonic processes that formed the East African Rift. These changes probably created highly variable environments and introduced selective pressures influencing the diversification of early apes. However, interpreting the connection between environmental dynamics and adaptive evolution is hampered by difficulties in locating taxa within specific ecological contexts: time-averaged or reworked deposits may not faithfully represent individual palaeohabitats. Here we present multiproxy evidence from Early Miocene deposits on Rusinga Island, Kenya, which directly ties the early ape Proconsul to a widespread, dense, multistoried, closed-canopy tropical seasonal forest set in a warm and relatively wet, local climate. These results underscore the importance of forested environments in the evolution of early apes
Analysis of visceral hyperalgesia in symptomatic subgroups of the "irritable bowel syndrome" : lowered bowel compliance or increased pain sensitivity?
Examines visceral hypersensitivity in three groups of irritable bowel syndrome (IBS) patients. It is suggested that visceral hypersensitivity, as demonstrated by a lower pain threshold to distension of the colon in IBS patients, could explain a major part of the clinical symptomatology of these patients. A total of 46 IBS patients (either diarrhea predominant, constipation predominant, or alternating diarrhea and constipation predominant) and 14 healthy controls participated in the study that compared sensation and motility responses to graded distensions of the sigmoid colon. Results supported findings from a previous study that show reduced volume thresholds of IBS patients with abdominal pain symptoms and diarrhea, but not in constipated patients and controls. This lowered colonic compliance is sufficient enough to explain visceral hypersensitivity as well as the correlated increases in elicited contractions in IBS patients. The increased pressure thresholds that were found demonstrated that these patients do not suffer from genuine hyperalgesia; rather, they experience an abnormal tonic reflex response that produces steeper pressure volume curves. Thresholds for non-nociceptive sensations exhibited the same pattern. Finally, no differences were found between groups in somatic pain sensitivity. It is concluded that reliable visceral pain tests are important for the differentiation of the IBS subgroups as well as for other syndromes with gastrointestinal pain
Insect Cell Expression and Purification of Recombinant SARS-COV-2 Spike Proteins That Demonstrate ACE2 Binding
The COVID-19 pandemic caused by SARS-CoV-2 infection has led to socio-economic shutdowns and the loss of over 5 million lives worldwide. There is a need for the identification of therapeutic targets to treat COVID-19. SARS-CoV-2 spike is a target of interest for the development of therapeutic targets. We developed a robust SARS-CoV-2 S spike expression and purification protocol from insect cells and studied four recombinant SARS-CoV-2 spike protein constructs based on the original SARS-CoV-2 sequence using a baculovirus expression system: a spike protein receptor-binding domain that includes the SD1 domain (RBD) coupled to a fluorescent tag (S-RBD-eGFP), spike ectodomain coupled to a fluorescent tag (S-Ecto-eGFP), spike ectodomain with six proline mutations and a foldon domain (S-Ecto-HexaPro(+F)), and spike ectodomain with six proline mutations without the foldon domain (S-Ecto-HexaPro(-F)). We tested the yield of purified protein expressed from the insect cell lines Spodoptera frugiperda (Sf9) and Trichoplusia ni (Tni) and compared it to previous research using mammalian cell lines to determine changes in protein yield. We demonstrated quick and inexpensive production of functional glycosylated spike protein of high purity capable of recognizing and binding to the angiotensin converting enzyme 2 (ACE2) receptor. To further confirm functionality, we demonstrate binding of eGFP fused construct of the spike ectodomain (S-Ecto-eGFP) to surface ACE2 receptors on lung epithelial cells by flow cytometry analysis and show that it can be decreased by means of receptor manipulation (blockade or downregulation)
Oxidative costs of reproduction in mouse strains selected for different levels of food intake and which differ in reproductive performance
We are grateful to the animal house staff for their care of the animals. This work was supported in part by the US National Institute of Health grants R01AG043972 to J.R.S. and D.B.A. and P30AG050886 and P30DK056336 to D.B.A. The opinions expressed are those of the authors and do not necessarily represent those of the N.I.H. or any other organization. A.H.A.J. was supported by an Iraqi government student scholarship.Peer reviewedPublisher PD
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Ecosystem dynamics of cropâpasture rotations in a fiftyâyear field experiment in Southern South America: Century model and field results.
The Century model was used to simulate soil C and N cycling and crop produc- tion dynamics in an ongoing field experiment in Uruguay (started in 1963). The model was calibrated using observed data from three treatments (crop or cropâpasture rotations) and validated with a fourth treatment. The model correctly predicted the impact of different treatments on microbial biomass, N mineralization, soil respi- ration, and crop yields. The model and observed data show that soil respiration, N mineralization, soil C, and crop yields increase with increasing plant-derived C inputs caused by increasing the frequency of pastures in the rotations. This is one of the first papers that show the strong positive correlation of observed soil C with plant C soil inputs to field-observed microbial biomass, soil respiration, and N mineralization. The results also showed that reducing tillage and transitioning to a no-till system increased soil C and reduced soil erosion. The main path of soil C losses was het- erotrophic microbial respiration, which accounted for 66% of the total C lost in a continuous crop rotation and no fertilizers, 71% in a continuous crop rotation with fertilizers, and 86% in a cropâpasture rotation with fertilizers. Model results from a degraded cropping system showed that adding grassâclover (Trifolium spp.) pastures greatly increased plant production and soil C, whereas reducing the frequency of grassâclover pastures in high-fertility cropping systems from 50% of the time to 25% reduces crop yields and soil C. Including cover crops substantially increases crop production and maintains soil C in high-fertility and degraded cropping systems
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The Hydrogen Futures Simulation Model (H[2]Sim) technical description.
Hydrogen has the potential to become an integral part of our energy transportation and heat and power sectors in the coming decades and offers a possible solution to many of the problems associated with a heavy reliance on oil and other fossil fuels. The Hydrogen Futures Simulation Model (H2Sim) was developed to provide a high level, internally consistent, strategic tool for evaluating the economic and environmental trade offs of alternative hydrogen production, storage, transport and end use options in the year 2020. Based on the model's default assumptions, estimated hydrogen production costs range from 0.68 /kg for centralized electrolysis using solar PV. Coal gasification remains the least cost option if carbon capture and sequestration costs (2/MBtu to compete with coal gasification. The electrolysis results are highly sensitive to electricity costs, but electrolysis only becomes cost competitive with other options when electricity drops below 1 cent/kWhr. Delivered 2020 hydrogen costs are likely to be double the estimated production costs due to the inherent difficulties associated with storing, transporting, and dispensing hydrogen due to its low volumetric density. H2Sim estimates distribution costs ranging from 1.37 /kg (long distance, high production volumes, carbon sequestration). Distributed hydrogen production options, such as on site natural gas, would avoid some of these costs. H2Sim compares the expected 2020 per mile driving costs (fuel, capital, maintenance, license, and registration) of current technology internal combustion engine (ICE) vehicles (0.55/mile), and electric vehicles (0.82-0.84 /mile), fuel cell vehicles with onboard gasoline reformation (FCVOB) (0.70 /mile). The results suggests that while the H2Hybrid vehicle may be competitive with ICE vehicles, it will be difficult for the FCV to compete without significant increases in gasoline prices, reduced predicted vehicle costs, stringent carbon policies, or unless they can offer the consumer something existing vehicles can not, such as on demand power, lower emissions, or better performance
Modular Robotic Vehicle
A modular robotic vehicle includes a chassis, driver input devices, an energy storage system (ESS), a power electronics module (PEM), modular electronic assemblies (eModules) connected to the ESS via the PEM, one or more master controllers, and various embedded controllers. Each eModule includes a drive wheel containing a propulsion-braking module, and a housing containing propulsion and braking control assemblies with respective embedded propulsion and brake controllers, and a mounting bracket covering a steering control assembly with embedded steering controllers. The master controller, which is in communication with each eModule and with the driver input devices, communicates with and independently controls each eModule, by-wire, via the embedded controllers to establish a desired operating mode. Modes may include a two-wheel, four-wheel, diamond, and omni-directional steering modes as well as a park mode. A bumper may enable docking with another vehicle, with shared control over the eModules of the vehicles
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