87,781 research outputs found
Spatio-temporal patterns of phenological development in Germany in relation to temperature and day length
No full textPhenological development of crops has been extensively studied in field experiments but less so at larger scales for which data availability is often limited. To what extent the spatio-temporal variability of crop development can be explained by relationships derived from field studies such as the temperature sum concept used in many crop models is unclear but the question could entail the large scale application of these models. The aim of this study was to analyze the spatio-temporal patterns of crop phenological development in response to temperature and day length. We used a comprehensive dataset (656,234 phenological observations at 6019 observation sites) about the phenology of oat (Avena sativa L.) and related climate data from Germany for the period 1959–2009. Our results show that the statistically significant warming trend since 1959 resulted in an earlier onset of all phenological stages and a shortening of most phenological phases with a 17-day earlier onset of yellow ripeness and a shortening of the “sowing to yellow ripeness” phase by 14 days. There was also a distinct spatial pattern in phenological development, with differences among eco-regions in the occurrence of development stages of 15–26 days and the length of the phases between stages of 6 and 21 days. Most of this spatio-temporal variability could be explained through the effects of temperature and day length. However, temperature sums (thermal times) and day length corrected temperature sums (photo-thermal times) also varied in time and space, pointing to the use of different varieties over time and across eco-regions. A considerable part of this variability in temperature sums and photo-thermal times could be explained by the mean temperature during the development periods. This may provide a means of modelling farmers’ adaptation to climate change using varieties of different maturity types; but it requires further investigation. The good agreement of the thermal and photo-thermal requirements of oat computed in this study with relationships known from field experiments supports the use of the temperature sum concept for large scale application to simulate crop phenology in response to temperature and day length. The analysis should be extended to other crops and regions to further evaluate the observed spatio-temporal patterns in crop phenology and the relationships explaining these patterns
Impact of data resolution on heat and drought stress simulated for winter wheat in Germany
No full textHeat and drought stress can reduce crop yields considerably which is increasingly assessed with crop models for larger areas. Applying these models originally developed for the field scale at large spatial extent typically implies the use of input data with coarse resolution. Little is known about the effect of data resolution on the simulated impact of extreme events like heat and drought on crops. Hence, in this study the effect of input and output data aggregation on simulated heat and drought stress and their impact on yield of winter wheat is systematically analyzed. The crop model SIMPLACE was applied for the period 1980–2011 across Germany at a resolution of 1 km × 1 km. Weather and soil input data and model output data were then aggregated to 10 km × 10 km, 25 km × 25 km, 50 km × 50 km and 100 km × 100 km resolution to analyze the aggregation effect on heat and drought stress and crop yield. We found that aggregation of model input and output data barely influenced the mean and median of heat and drought stress reduction factors and crop yields simulated across Germany. However, data aggregation resulted in less spatial variability of model results and a reduced severity of simulated stress events, particularly for regions with high heterogeneity in weather and soil conditions. Comparisons of simulations at coarse resolution with those at high resolution showed distinct patterns of positive and negative deviations which compensated each other so that aggregation effects for large regions were small for mean or median yields. Therefore, modelling at a resolution of 100 km × 100 km was sufficient to determine mean wheat yield as affected by heat and drought stress for Germany. Further research is required to clarify whether the results can be generalized across crop models differing in structure and detail. Attention should also be given to better understand the effect of data resolution on interactions between heat and drought impacts
Independent and combined effects of high temperature and drought stress around anthesis on wheat
No full textHigh temperature and drought stress are projected to reduce crop yields and threaten food security. While effects of heat and drought on crop growth and yield have been studied separately, little is known about the combined effect of these stressors. We studied detrimental effects of high temperature, drought stress and combined heat and drought stress around anthesis on yield and its components for three wheat cultivars originating from Germany and Iran. We found that effects of combined heat and drought on the studied physiological and yield traits were considerably stronger than those of the individual stress factors alone, but the magnitude of the effects varied for specific growth- and yield-related traits. Single grain weight was reduced under drought stress by 13%–27% and under combined heat and drought stress by 43%–83% but not by heat stress alone. Heat stress significantly decreased grain number by 14%–28%, grain yield by 16%–25% and straw yield by 15%–25%. Cultivar responses were similar for heat but different for drought and combined heat and drought treatments. We conclude that heat stress as imposed in this study is less detrimental than the effects of those other studied stresses on growth and yield traits
Will Astronauts Wash Clothes on the Way to Mars?
No full textBellevue, WashingtonMichael K. Ewert, NASA Johnson Space Center, USAFrank F. Jeng, NASA Johnson Space Center, USAThe 45th International Conference on Environmental Systems was held in Bellevue, Washington, USA on 12 July 2015 through 16 July 2015.Future human space exploration missions will lengthen to years, and keeping crews clothed without a huge resupply burden is an important consideration for habitation systems. A space laundry system could be the solution; however, the resources it uses must be accounted for and must win out over the reliable practice of simply bringing along enough spare underwear. NASA has conducted trade-off studies through its Logistics Reduction Project to compare current space clothing systems, life extension of that clothing, traditional water-based clothes washing, and other sanitizing techniques. The best clothing system depends on the mission and assumptions but, in general, analysis results indicate that washing clothes on space missions will start to pay off as mission durations approach a year
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Adaptation of crop production to climate change by crop substitution
No full textResearch on the impact of climate change on agricultural production has mainly focused on the effect of climate and its variability on individual crops, while the potential for adapting to climate change through crop substitution has received less attention. This is surprising because the proportions of individual crops in the total crop area have changed considerably over periods of time much shorter than those typically investigated in climate change studies. The flexibility of farmers to adapt to changing socioeconomic and environmental conditions by changing crop type may therefore also represent an alternative option to adapt to climate change. The objective of this case study was to investigate the potential of crop substitution as an adaptation strategy to climate change. We compared biomass yield and water use efficiency (WUE) of maize (Zea mays L) and pearl millet (Pennisetum americanum L.) grown in the semi-arid northeast of Iran for fodder production under present and potential future climatic conditions. Climate change projections for the baseline period 1970–2005 and two future time periods (2011–2030 and 2080–2099) from two emission scenarios (A2 and B1) and four general circulation models were downscaled to daily time steps using the Long Ashton Research Station-Weather Generator (LARS-WG5). Above-ground biomass was simulated for seven research sites with the Decision Support System for Agrotechnology Transfer (DSSAT 4.5) model which was calibrated and tested with independent experimental data from different field experiments in the region. The analysis of observations across all study locations showed an inverse relationship between temperature and biomass yield for both pearl millet and maize. Biomass yield was most sensitive to the duration of the phenological phase from floral initiation to end of leaf growth. For this phase we also found the highest negative correlation between mean temperature and biomass yield, which was more pronounced for pearl millet than for maize. This relationship was well reproduced by the crop model, justifying its use for the assessment. Due to the higher sensitivity of pearl millet to temperature increase, simulations suggest that the maximum benefit of crop substitution for biomass yield and WUE is to be gained for present-day conditions and would decline under future warming. The simulated increase in biomass yield due to substitution of maize by pearl millet was nevertheless larger than the yield decrease from potential climate change. Therefore, substituting maize by pearl millet should be considered as a measure for increasing fodder production in the investigated region. Differences in yields of crops that may substitute for each other because of similar use have been shown for other regions under current and potential future climatic conditions as well, so that we suggest that our findings are of general importance for climate change research. More research is required to quantify the effects for other crop combinations, regions, and interactions with other adaptation measures
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
John F. Kennedy telegram to Roosevelt
No full textJersey Homesteads (later the Borough of Roosevelt) was established in the 1930s as an agro-industrial cooperative community. It was established specifically for urban Jewish garment workers, many of whom had emigrated from Europe. President John F. Kennedy sent a telegram to the citizens of Roosevelt, New Jersey, apologizing for not being able to attend the memorial dedication in honor of former President Franklin Delano Roosevelt. (Jersey Homesteads became Roosevelt in 1945 in honor of the president.) President Kennedy expressed his gratitude to the people of Roosevelt for constructing the memorial, and commented that it will serve as a constant reminder of Roosevelt's good works
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
- …
