Polytopic multiplexing is a new method of overlapping holograms that, when combined with other multiplexing techniques, can increase the capacity of a volume holographic data storage system by more than a factor of 10. This is because the method makes possible the effective utilization of thick media. An experimental demonstration of this technique is also presented.
[1] The Suomi National Polar-Orbiting Partnership (NPP) satellite was launched on 28 October 2011 and carries the Advanced Technology Microwave Sounder (ATMS) on board. ATMS is a cross-track scanning instrument observing in 22 channels at frequencies ranging from 23 to 183 GHz, permitting the measurements of the atmospheric temperature and moisture under most weather conditions. In this study, the ATMS radiometric calibration algorithm used in the operational system is first evaluated through independent analyses of prelaunch thermal vacuum data. It is found that the ATMS peak nonlinearity for all the channels is less than 0.5 K, which is well within the specification. For the characterization of the ATMS instrument sensitivity or noise equivalent differential temperatures (NEDT), both standard deviation and Allan variance of warm counts are computed and compared. It is shown that NEDT derived from the standard deviation is about three to five times larger than that from the Allan variance. The difference results from a nonstationary component in the standard deviation of warm counts. The Allan variance is better suited than the standard deviation for describing NEDT. In the ATMS sensor brightness temperature data record (SDR) processing algorithm, the antenna gain efficiencies of main beam, cross-polarization beam, and side lobes must be derived accurately from the antenna gain distribution function. However, uncertainties remain in computing the efficiencies at ATMS high frequencies. Thus, ATMS antenna brightness temperature data records (TDR) at channels 1 to 15 are converted to SDR with the actual beam efficiencies whereas those for channels 16 to 22 are only corrected for the near-field sidelobe contributions. The biases of ATMS SDR measurements to the simulations are consistent between GPS RO and NWP data and are generally less than 0.5 K for those temperature-sounding channels where both the forward model and input atmospheric profiles are reliable.
bioRxiv was founded on the premise that publicly posting preprints would allow authors to receive feedback and submit improved papers to journals. This paper analyses a number of trends against this stated purpose, namely, the timing of preprint postings relative to submission to accepting journals; trends in the rate of unpublished preprints over time; trends in the timing of publication of preprints by accepting journals; and trends in the concentration of published, reviewed preprints by publisher. Findings show that a steady c.30% of preprints remain unpublished and that the majority is posted onto bioRxiv close to or after submission – therefore giving no time for feedback to help improve the articles. Four publishers (Elsevier, Nature, PLOS, and Oxford University Press) account for the publication of 47% of bioRxiv preprints. Taken together, it appears that bioRxiv is not accomplishing its stated goals and that authors may be using the platform more to establish priority, as a marketing enhancement of papers, and as functional Green OA, rather than as a community‐driven source of prepublication review.
On 26 December 2004 the Indonesian subduction zone near the northern end of Sumatra began to rupture at 58 minutes, 47 seconds past midnight Greenwich Mean Time. The rupture continued for approximately seven minutes, extending northwestward along the Sunda Trench for roughly 1200 km to the Andaman Islands. The seafloor displacement generated a massive tsunami that swept ashore with 10‐m amplitude in northern Sumatra and expanded across the Indian Ocean and Andaman Sea, striking Sri Lanka and Thailand within two hours of the rupture. Confirmed deaths along the coastlines of 11 Indian Ocean nations exceed 220,000, marking this as one of the most lethal natural disasters in human history
Accurate global observations from space are critical for global climate change study. However, atmospheric temperature trend derived from spaceborne microwave instruments remains a subject of debate, due mainly to the uncertainty in characterizing the long-term drift of instrument calibration. Thus, a highly stable target with a well-known microwave radiation is required to evaluate the long-term calibration stability. This paper develops a new model to simulate the lunar emission at microwave frequencies, and the model is then used for monitoring the stability of the Advanced Technology Microwave Sounder (ATMS) onboard Suomi NPP satellite. It is shown that the ATMS cold space view of lunar radiation agrees well with the model simulation during the past five years and this instrument is capable of serving the reference instrument for atmospheric temperature trending studies, and connecting the previous generation of microwave sounders from NOAA-15 to the future Joint Polar Satellite System Microwave Sounder onboard NOAA-20 satellite.
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