693 research outputs found
Am J Hematol
No full textHemophilia B (HB) is a disorder resulting from genetic mutations in the Factor 9 gene (F9). Genotyping of HB patients is important for genetic counseling and patient management. Here we report a study of mutations identified in a large sample of HB patients in the US. Patients were enrolled through an inhibitor surveillance study at 17 hemophilia treatment centers. A total of 87 unique mutations were identified from 225 of the 226 patients, including deletions, insertions, and point mutations. Point mutations were distributed throughout the F9 gene and were found in 86% of the patients. Of these mutations, 24 were recurrent in the population, and 3 of them (c.316G>A, c.1025C>T, and c.1328T>A) accounted for 84 patients (37.1%). Haplotype analysis revealed that the high recurrence arose from a founder effect. The severity of HB was found to correlate with the type of mutation. Inhibitors developed only in severe cases with large deletions and nonsense mutations. None of the mild or moderate patients developed inhibitors. Our results provide a resource describing F9 mutations in US HB patients and confirm previous findings that patients bearing large deletions and nonsense mutations are at high risk of developing inhibitors.CC999999/Intramural CDC HHSUnited States
Development of polymers for non-CAR resists for EUV lithography
No full textThree strategies for approaching the design and synthesis of non-chemically amplified resists (non-CARs) are presented. These are linear polycarbonates, star polyester-blk-poly(methyl methacrylate) and comb polymers with polysulfone backbones. The linear polycarbonates were designed to cleave when irradiated with 92 eV photons and high Tg alicyclic groups were incorporated into the backbone to increase Tg and etch resistance. The star block copolymers were designed to have a core that is sensitive to 92 eV photons and arms that have the potential to provide properties such as high Tg and etch resistance. Similarly the polysulfone comb polymers were designed to have an easily degradable polymer backbone and comb-arms that impart favorable physical properties. Initial patterning results are presented for a number of the systems
Active noise cancellation in a suspended interferometer
No full textWe demonstrate feed-forward vibration isolation on a suspended Fabry-Perot interferometer using Wiener filtering and a variant of the common least mean square adaptive filter algorithm. We compare the experimental results with theoretical estimates of the cancellation efficiency. Using data from the recent Laser InterferometerGravitational Wave Observatory (LIGO) Science Run, we also estimate the impact of this technique on full scale gravitational waveinterferometers. In the future, we expect to use this technique also to remove acoustic, magnetic, and gravitational noise perturbations from the LIGOinterferometers. This noise cancellation technique is simple enough to implement in standard laboratory environments and can be used to improve signal-to-noise ratio for a variety of high precision experiments.National Science Foundation (U.S.) (Grant PHY-0555406
Antireflective subwavelength patterning of IR optics
No full textpeer reviewedThermal infrared (IR) lenses require efficient anti-reflection coating. Moth-eye (or egg-box) 2D subwavelength gratings have demonstrated their ability to reach a very high transmission for a wide wavelength and angular range. The use in thermal IR is simplified by the lower resolution for lithographic technology, compared to visible waveband. However, deeper structures must be engraved and lithography must be adapted to IR materials. In order to be cost-effective, the
patterning must be produced by replication techniques, such as embossing. Our laboratory is now experimenting hot embossing of moth-eye patterns in chalcogenide substrates. In this paper, theoretical analysis, micro-lithographic technology and manufacturing processes are detailed
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Huanglongbing Resistance and Tolerance in Citrus
No full textHuanglongbing (HLB) is severely impacting Florida citrus. Productivity declines in many HLB-affected genotypes, often with greatly thinned canopies. Fruit size and quality are often adversely affected as the disease advances. HLB was assessed in diverse cultivars in commercial groves with high HLB-incidence. ‘Temple’ had the lowest HLB symptoms and Liberibacter (Las) titer, while ‘Murcott’ and ‘Minneola’ had the highest. The USDA Ft. Pierce, FL farm is managed to reveal genotype responses to HLB. Some current cultivars and hybrid seedlings demonstrate resistance/tolerance, at least to strain(s) of Las present. C. trifoliata is the best documented citrus resistance source with Las titers suppressed even when C. trifoliata is grafted onto severely-infected rootstocks. Some cultivars and hybrids have abundant foliage symptoms, but full canopies and seemingly normal fruit set and size. In 3-years of data from a replicated trial of ‘Triumph’(T), ‘Jackson’(J), ‘Flame’(F), and ‘Marsh’(M), HLB symptoms were severe in all trees and Liberibacter titers were similar. However, F&M were almost completely defoliated in some years while T&J had full canopies. Cumulative fruit/tree was greater for T&J (255&220) than for F&M (29&66). T&J fruit met commercial standards and had normal size but F&M fruit were unacceptable with many small and misshapen. Evidence mounts that useful resistance/tolerance to HLB is present in cultivated citrus and this is a focus of the USDA citrus breeding program
Semantic annotation of ubiquitous learning environments
No full textSkills-based learning environments are used to promote the acquisition of practical skills as well as decision making, communication, and problem solving. It is important to provide feedback to the students from these sessions and observations of their actions may inform the assessment process and help researchers to better understand the learning process. Through a series of prototype demonstrators, we have investigated the use of semantic annotation in the recording and subsequent understanding of such simulation environments. Our Semantic Web approach is outlined and conclusions drawn as to the suitability of different annotation methods and their combination with ubiquitous computing techniques to provide novel mechanisms for both student feedback and increased understanding of the learning environment
Scaling Laws for the Noise-equivalent Angle and C-tilt, G-tilt Anisoplanatism Due to Scintillation
No full textIn this paper, we derive single-integral solutions, applicable in the weak-to-moderate scintillation regime, for both the noise equivalent angle (NEA) due to scintillation and the scintillation-induced root mean squared error (RMSE) between gradient tilt (G-tilt) and centroid tilt (C-tilt). In practice, the NEA due to scintillation gives a measure of the scintillation-induced track error, whereas the scintillation-induced RMSE between C-tilt and G-tilt gives a measure of the C-tilt, G-tilt anisoplanatism due to scintillation. Assuming spherical-wave propagation, we fit closed-form expressions to the numerically integrated solutions. These closed-form expressions serve as “scaling laws,” and we validate their use with wave-optics simulations. At large, we determine that the one-axis NEA due to scintillation scales as a function of aperture size, propagation distance, wavelength, and Rytov number, whereas the one-axis scintillation-induced RMSE between C-tilt and G-tilt scales proportionally to the Rytov number when normalized by the diffraction angle. These findings will aid in the design of active electro-optical systems, which inevitably experience the effects of scintillation when imaging through distributed-volume turbulence
Pre-emptive infrared countermeasures
No full textThe aim of this PhD is to investigate pre-emptive flare release compared to reactive flare release and their efficacy as a countermeasure device in the protection of fast jet and transport aircraft against the MANPAD threat. Implicit in this is to study the optimum release time of the flare decoy. Consequently, this also raises the question of whether flares of reduced payload size can be as effective as standard flares when released at this optimum time.
To achieve these aims the initial step is to develop models for the different types of Man-Portable Air-Defence (MANPAD) systems and the IR seekers they utilise. This also requires the simulation of the full pre-launch process, namely the acquisition of the target to obtain lock-on then the application of lead and super elevation to give a more realistic model of the firing sequence. Two target models are also developed, a fast jet (AMX-A1) and a transport aircraft (C130), with realistic positions and ejection characteristics for the countermeasure (CM) dispensers.
The next stage includes a counter-countermeasure (CCM) capability in the IR seekers. The first is a track angle bias with values optimised for the two aircraft models. Second is the development of a two-colour seeker with signal processors designed for both a spinscan and a conscan system.
Using all MANPAD models flares are released at intervals throughout the engagements to find the optimum firing time and the simulations repeated for flares with reduced peak intensity and burn time. The results show that flare release around the time of missile launch is effective against most threats, even the more advanced MANPADs with CCMs. Also, that for reduced performance flares maintaining the burn time is perhaps more important than the peak intensity
A gravitational wave observatory operating beyond the quantum shot-noise limit
No full textAround the globe several observatories are seeking the first direct detection of gravitational waves (GWs). These waves are predicted by Einstein’s general theory of relativity and are generated, for example, by black-hole binary systems. Present GW detectors are Michelson-type kilometre-scale laser interferometers measuring the distance changes between mirrors suspended in vacuum. The sensitivity of these detectors at frequencies above several hundred hertz is limited by the vacuum (zero-point) fluctuations of the electromagnetic field. A quantum technology—the injection of squeezed light—offers a solution to this problem. Here we demonstrate the squeezed-light enhancement of GEO600, which will be the GWobservatory operated by the LIGO Scientific Collaboration in its search for GWs for the next 3–4 years. GEO600 now operates with its best ever sensitivity, which proves the usefulness of quantum entanglement and the qualification of squeezed light as a key technology for future GW astronomy.J. Abadie... M.R. Ganija... D.J. Hosken... J. Munch... D.J. Ottaway... P.J. Veitch... et al. J. Abadie... M. R. Ganija...D. J. Hosken... J. Munch... D. J. Ottaway... P. J. Veitch... et al., (LIGO Scientific Collaboration
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