The planispheric astrolabe occupies a special place among early scientific instruments because of its mathematical sophistication, its elegant appearance, and its usefulness to astronomers in pre-telescopic times. The operation of the astrolabe is based on the mathematical properties of stereographic projection, concepts that were understood by the time of Ptolemy in the second century a.d., although surviving instruments are from much later periods.
The New Urbanism has invigorated city planning history by invoking the tradition of American civic design to solve the conundrum of suburban sprawl. Studies have documented the similarities between the works of pioneer planner John Nolen and Andres Duany and Elizabeth Plater-Zyberk, but the ethic connecting past and present remains vague. This research presents the origins of the garden city ethic John Nolen introduced to the United States and its potential to foster a sustainable planning system capable of enlivening American civic culture.
We provide an analysis of the galactic cosmic ray radiation environment of Earth's atmosphere using measurements from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) aboard the Lunar Reconnaissance Orbiter (LRO) together with the Badhwar‐O'Neil model and dose lookup tables generated by the Earth‐Moon‐Mars Radiation Environment Module (EMMREM). This study demonstrates an updated atmospheric radiation model that uses new dose tables to improve the accuracy of the modeled dose rates. Additionally, a method for computing geomagnetic cutoffs is incorporated into the model in order to account for location‐dependent effects of the magnetosphere. Newly available measurements of atmospheric dose rates from instruments aboard commercial aircraft and high‐altitude balloons enable us to evaluate the accuracy of the model in computing atmospheric dose rates. When compared to the available observations, the model seems to be reasonably accurate in modeling atmospheric radiation levels, overestimating airline dose rates by an average of 20%, which falls within the uncertainty limit recommended by the International Commission on Radiation Units and Measurements (ICRU). Additionally, measurements made aboard high‐altitude balloons during simultaneous launches from New Hampshire and California provide an additional comparison to the model. We also find that the newly incorporated geomagnetic cutoff method enables the model to represent radiation variability as a function of location with sufficient accuracy.
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