3,285 research outputs found

    “Amidst the Chime of the Razor Wire”: Narrating Poetic Justice in Guantanamo Bay

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    The quest of poetic justice carries Marc Falkoff’s 2007 anthology Poems from Guantanamo: The Detainees Speak into the court of public (literary) opinion. While the Pentagon asserts that poetry poses special security risks, and related translation issues may obscure the artistry or message of some of the 17 poets’ verse, Falkoff’s volume nevertheless gives prisoners’ voices a forum in which they might be heard. At the nexus of legal and literary scholarship, poetic voice and its expression become a site of deconstructing identity. The Guantanamo poets invite readers to explore the ways that aesthetics form perceptions of their identity as alleged enemy combatants, creating a literary forum which replaces the traditional courtroom

    Ammonia uptake and release in the MnX<sub>2</sub>–NH<sub>3</sub> (X = Cl, Br) systems and structure of the Mn(NH<sub>3</sub>)nX<sub>2</sub> (n = 6, 2) ammines

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    Hexa-ammine complexes, Mn(NH&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;6&lt;/sub&gt;X&lt;sub&gt;2&lt;/sub&gt; (X = Cl, Br), have been synthesized by ammoniation of the corresponding transition metal halide and characterized by Powder X-ray diffraction (PXRD) and Raman spectroscopy. The hexa-ammine complexes are isostructural (Cubic,Fm-3m, Z = 4; a = 10.2742(6) Ă… and 10.527(1) Ă… for X = Cl, Br respectively). Temperature programmed desorption (TPD) demonstrated that ammonia release from Mn(NH&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;6&lt;/sub&gt;X&lt;sub&gt;2&lt;/sub&gt; complexes occurred in three stages corresponding to the release of 4, 1 and 1 NH&lt;sub&gt;3&lt;/sub&gt; equivalents respectively. The chloride and bromide both exhibit a deammoniation onset temperature below 323 K. The di-ammoniates from the first desorption step were isolated during TPD measurements and their crystal structures determined by Rietveld refinement against PXRD data (X = Cl: orthorhombicCmmm, a = 8.1991(9) Ă…, b = 8.2498(7) Ă…, c = 3.8212(4) Ă…, Z = 2; X = Br: orthorhombic Pbam, a = 6.0109(5) Ă…, b = 12.022(1) Ă…, c = 4.0230(2) Ă…, Z= 2)

    A new B-dot probe-based diagnostic for amplitude, polarization, and wavenumber measurements of ion cyclotron range-of frequency fields on ASDEX Upgrade

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    A new B-dot probe-based diagnostic has been installed on an ASDEX Upgrade tokamak to characterize ion cyclotron range-of frequency (ICRF) wave generation and interaction with magnetized plasma. The diagnostic consists of a field-aligned array of B-dot probes, oriented to measure fast and slow ICRF wave fields and their field-aligned wavenumber (k(//)) spectrum on the low field side of ASDEX Upgrade. A thorough description of the diagnostic and the supporting electronics is provided. In order to compare the measured dominant wavenumber of the local ICRF fields with the expected spectrum of the launched ICRF waves, in-air near-field measurements were performed on the newly installed 3-strap ICRF antenna to reconstruct the dominant launched toroidal wavenumbers (k(tor)). Measurements during a strap current phasing scan in tokamak discharges reveal an upshift in k(//) as strap phasing is moved away from the dipole configuration. This result is the opposite of the k(tor) trend expected from in-air near-field measurements; however, the near-field based reconstruction routine does not account for the effect of induced radiofrequency (RF) currents in the passive antenna structures. The measured exponential increase in the local ICRF wave field amplitude is in agreement with the upshifted k(//), as strap phasing moves away from the dipole configuration. An examination of discharges heated with two ICRF antennas simultaneously reveals the existence of beat waves at 1 kHz, as expected from the difference of the two antennas' operating frequencies. Beats are observed on both the fast and the slow wave probes suggesting that the two waves are coupled outside the active antennas. Although the new diagnostic shows consistent trends between the amplitude and the phase measurements in response to changes applied by the ICRF antennas, the disagreement with the in-air near-field measurements remains. An electromagnetic model is currently under development to address this issue. (C) 2015 AIP Publishing LLC

    Loading tests of a wing structure for a hypersonic aircraft

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    Room-temperature loading tests were conducted on a wing structure designed with a beaded panel concept for a Mach 8 hypersonic research airplane. Strain, stress, and deflection data were compared with the results of three finite-element structural analysis computer programs and with design data. The test program data were used to evaluate the structural concept and the methods of analysis used in the design. A force stiffness technique was utilized in conjunction with load conditions which produced various combinations of panel shear and compression loading to determine the failure envelope of the buckling critical beaded panels The force-stiffness data did not result in any predictions of buckling failure. It was, therefore, concluded that the panels were conservatively designed as a result of design constraints and assumptions of panel eccentricities. The analysis programs calculated strains and stresses competently. Comparisons between calculated and measured structural deflections showed good agreement. The test program offered a positive demonstration of the beaded panel concept subjected to room-temperature load conditions

    Integrated spatial multiplexing of heralded single photon sources

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    The non-deterministic nature of photon sources is a key limitation for single photon quantum processors. Spatial multiplexing overcomes this by enhancing the heralded single photon yield without enhancing the output noise. Here the intrinsic statistical limit of an individual source is surpassed by spatially multiplexing two monolithic silicon correlated photon pair sources, demonstrating a 62.4% increase in the heralded single photon output without an increase in unwanted multi-pair generation. We further demonstrate the scalability of this scheme by multiplexing photons generated in two waveguides pumped via an integrated coupler with a 63.1% increase in the heralded photon rate. This demonstration paves the way for a scalable architecture for multiplexing many photon sources in a compact integrated platform and achieving efficient two photon interference, required at the core of optical quantum computing and quantum communication protocols.Comment: 10 pages, 3 figures, comments welcom

    Hybrid approach to complex thoracic aortic aneurysms in high-risk patients: Surgical challenges and clinical outcomes

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    BackgroundEndovascular therapy is a less invasive alternative treatment for high-risk patients with thoracic aortic aneurysms. However, this technology alone is often not applicable to complex aneurysmal morphology. The purpose of this study was to evaluate the utility of hybrid strategies in high-risk patients who are otherwise unsuitable for endovascular therapy alone.MethodsDuring an 18-month period, 31 high-risk patients (mean age, 69 years; range, 52-89 years) underwent combined open and endovascular approaches for complex aneurysms, including 16 patients with ascending and arch aneurysms and 15 patients with aneurysms involving visceral vessels. Among them, 11 patients had histories of aneurysm repairs. To overcome the anatomic limitations of endovascular repairs, various adjunctive surgical maneuvers were used, including aortic arch reconstruction in 3 patients, supra-aortic trunk debranching in 13 patients (including 8 patients who required aortas as inflow sources), and visceral vessel bypasses in 15 patients (including 10 patients who required bypasses to all 3 visceral branches). Additionally, carotid artery access was obtained in 1 patient, and iliac artery conduits were created in 12 patients.ResultsTechnical success was achieved in all patients. There was one perioperative death (3.2%) due to postoperative bleeding. Two patients (6.4%) had immediate type II endoleaks, which were resolved by the 1-month follow-up. Other procedure-related complications occurred in three patients (9.6%), including renal bypass thromboses in two patients and retroperitoneal hematoma, which was successfully managed conservatively, in one patient. During a mean follow-up of 16 months, two patients died of unrelated causes, whereas the remainder of patients were asymptomatic, without aneurysm enlargement.ConclusionsOur study highlights how hybrid strategies incorporating surgical and endovascular approaches can be used successfully in treating patients with complex thoracic aortic aneurysms. This combined approach potentially expands the field of endovascular stent grafting and is an attractive solution for patients with poor cardiopulmonary reserves
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