1,017 research outputs found
Enlightened defense: The national security *policy of Thomas Jefferson
The triumph of Thomas Jefferson and the Democratic Republicans in 1800 left the deposed Federalists aghast at what this Francophile, anti nationalist, reputedly atheistic president might do to the country. Despite Jefferson\u27s impulses toward pacifism, national isolation, the diffusion of political power, and healing faction, the eight years of his two administrations were destined to be as calm as a hurricane. The turbulent situation in Europe had already made a mockery of Washington\u27s advice to avoid entanglement, and during Jefferson\u27s presidency, the dangers only increased.;Jefferson\u27s ideas on national security were diametrically opposed to those of Alexander Hamilton and the Federalists. Jefferson was an advocate of states\u27 rights, but Hamilton of centralized power. Jefferson wanted to avoid debt, while Hamilton thought debt was a positive and unifying factor. Jefferson believed in maintaining a minuscule standing military in favor of state militias, whereas Hamilton called for a huge, regular army and a sea-going navy. The debate was not an academic one: the young nation was literally surrounded by enemies and potential enemies. Spain had a stranglehold on New Orleans, and the slightest pressure there could (and sometimes did) throttle the entire economy of the American west. Britain, with a firm hold on Canada and total domination of the high seas, bullied the Americans with seemingly unfair commercial practices. When Napoleon began to restrict trade as well, Jefferson and his countrymen faced economic calamity and the threat of wars they would not likely win.;Jefferson introduced legislation that altered the structure of both the army and navy, established the military academy at West Point, and changed the political constitution of the defense establishment. He fought a long, frustrating war with Tripoli, fended off insults from Europe, and struggled to formulate an Indian policy that would protect native Americans while dealing with the reality and inevitability of white domination of the continent. Jefferson also pulled off the most spectacular land deal in history: the Louisiana Purchase---an accretion that doubled the size of the young republic and sowed the seeds for the eventual triumph of Jefferson\u27s strategic calculations.;By the end of his second term, however, Jefferson\u27s initial successes had been eclipsed by the disappointing results of his embargo against Great Britain. Historians roundly condemn the embargo as both ineffective and a direct violation of Jefferson\u27s own ideas on governance. His handling of the military has also been criticized, particularly in the light of America\u27s martial mediocrity in the War of 1812---shortfalls that can be partially attributed to Jefferson\u27s underfunding of the army and navy.;This essay looks critically at the military and national security policies of Thomas Jefferson with a view to penetrating beyond traditional interpretations. By examining closely the political, economic, social, and military context of the times---especially the delicate domestic situation---it is possible to see Jefferson\u27s policies with a new appreciation of how enlightened and ultimately effective they really were
Data analysis and archival
The purpose of this task is the acquisition, distribution, archival, and analysis of data collected during and in support of the Upper Atmospheric Research Program (UARP) field experiments. Meteorological and U2 data from the 1984 Stratosphere-Troposphere Exchange Project (STEP) was analyzed to determine characteristics of internal atmospheric waves. CDROM's containing data from the 1987 STEP, 1987 Airborne Antarctic Ozone Expedition (AAOE), and the 1989 Airborne Arctic Stratospheric Expedition (AASE) were produced for archival and distribution of those data sets. The AASE CDROM contains preliminary data and a final release is planned for February 1990. Comparisons of data from the NASA ER-2 Meteorological Measurement System (MMS) with radar tracking and radiosonde data show good agreement. Planning for a Meteorological Support Facility continues. We are investigating existing and proposed hardware and software to receive, manipulate, and display satellite imagery and standard meteorological analyses, forecasts, and radiosonde data
Adaptive optics testbed for pre- and post-compensation of earth-to-geo optical communication: downlink results
Optical communication between optical ground stations (OGS) and geostationary (GEO) satellites is a promising technology for future high-speed data transfer between Earth and space. However, such optical communication links suffer from distortions caused by atmospheric turbulence. To explore adaptive optics mitigation of this effect both in the uplink and the downlink beam, we have developed an adaptive optics testbed. In an earlier publication [1], we reported on the results of uplink compensation. In this contribution, we wish to elaborate more on the efficiency of downlink compensation. Further, we will highlight the differences between uplink and downlink compensation
An assessment of age determination in fossil fish: the case of the opercula in the Mesozoic actinopterygian Saurichthys
Analyzing and interpreting life history data (e.g., aging and longevity, age at sexual maturity) are fundamental in many paleontological studies. In the case of extant and fossil fishes, otoliths, and to a lesser degree other incrementally growing hard tissue structures such as scales and bones, have been utilized to reveal these data. We investigated the microanatomy and internal microstructure of opercula of Saurichthys, one of the most easily recognized and globally distributed fishes in the Triassic, to elucidate whether these prominent skull bones provide reliable age estimates. Opercula, and where the subopercula is present, of several outgroup taxa were sectioned to provide a phylogenetic framework for the study. The external protrusions and ridges or internal concentric bands or wrinkles are not related to internal age-related bone tissue structures such as annuli and growth zones, but are instead purely ornamental in the case of the former and probably structural/taphonomic in case of the latter. Opercular morphogenesis of Saurichthys opercula differs from that of the extant outgroups examined in that they show rostro-medial to caudo-lateral extending growth increments instead of ones that extend sub-parallel to the opercular bone surfaces. Individual age data could thus not be reliably extracted from those opercula. Furthermore, an odontode-like complex was not encountered in Saurichthys opercula, but a few specimens show a peculiar, weakly birefringent thin tissue layer of unknown origin filling the valleys between the external ornamental ridges. Although all Saurichthys opercula showed growth marks, these could not be counted to produce reliable individual age data, whereas bones with a more concentric cross section, such as the ceratohyal, appear better suited for this purpose
Sonoelastography of the Common Flexor Tendon of the Elbow with Histologic Agreement: A Cadaveric Study.
Purpose To determine the correlation of the results of conventional B-mode ultrasonography (US) and compression sonoelastography with histologic results in common flexor tendons of the elbow in human cadavers. Materials and Methods Twenty-five common flexor tendons were evaluated in 16 fresh, unembalmed cadavers of 11 women with a median age of 85 years (range, 71-101 years) and five men with a median age of 78 years (range, 70-88 years). Informed consent was provided according to the last will of the donors. B-mode US results were classified as grade 1, normal tendon with homogeneous fibrillar pattern; grade 2, tendon thickening or hypoechoic areas and/or calcifications in less than 30% of the tendon; or grade 3, hypoechoic areas and/or calcifications greater than 30% of the tendon. Sonoelastographic results were grade 1, blue (hardest) to green (hard); grade 2, yellow (soft); and grade 3, red (softest). The intraclass correlation coefficient was calculated to determine agreement with histologic findings for each B-mode US, sonoelastographic, and combined B-mode US and sonoelastographic examination. Histologic results were grade 1, normal, with parallel fibrillar pattern; grade 2, mild tendinopathy, with cellular infiltration, angiogenesis, or fatty vacuoles; or grade 3, severe tendinopathy, with loss of parallel collagen structure and necrosis. Results Histologic alterations were detected in 44% (11 of 25) of biopsy specimens. Intraclass correlation with histologic results was 0.57 for B-mode US, 0.68 for sonoelastography, and 0.84 for the combination of the two approaches. Conclusion The addition of sonoelastography to B-mode US provided statistically significant improvement in correlation with histologic results compared with the use of B-mode US alone (P \u3c .02). (©) RSNA, 2016 Online supplemental material is available for this article
Cloaking and imaging at the same time
In this letter, we propose a conceptual device to perform subwavelength
imaging with positive refraction. The key to this proposal is that a drain is
no longer a must for some cases. What's more, this device is an isotropic
omnidirectional cloak with a perfect electric conductor hiding region and shows
versatile illusion optical effects. Numerical simulations are performed to
verify the functionalities.Comment: 15 pages, 4 figure
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