23,108 research outputs found

    Three-meter balloon-borne telescope

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    The Three-Meter Balloon-Borne Telescope is planned as a general purpose facility for making far-infrared and submillimeter astronomical observations from the stratosphere. It will operate throughout the spectral range 30 microns to 1 millimeter which is largely obscurred from the ground. The design is an f/13.5 Cassegrain telescope with an f/1.33 3-meter primary mirror supported with a 3-axis gimbal and stabilization system. The overall structure is 8.0 m high by 5.5 m in width by 4.0 m in depth and weighs 2000 kg. This low weight is achieved through the use of an ultra lightweight primary mirror of composite construction. Pointing and stabilization are achieved with television monitoring of the star field, flex-pivot bearing supports, gyroscopes, and magnetically levitated reaction wheels. Two instruments will be carried on each flight; generally a photometric camera and a spectrometer. A 64-element bolometer array photometric camera operating from 30 to 300 microns is planned as part of the facility. Additional instruments will be derived from KAO and other development programs

    Balloon-borne three-meter telescope for far-infrared and submillimeter astronomy

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    The scientific objectives, engineering analysis and design, results of technology development, and focal-plane instrumentation for a two-meter balloon-borne telescope for far-infrared and submillimeter astronomy are presented. The unique capabilities of balloon-borne observations are discussed. A program summary emphasizes the development of the two-meter design. The relationship of the Large Deployable Reflector (LDR) is also discussed. Detailed treatment is given to scientific objectives, gondola design, the mirror development program, experiment accommodations, ground support equipment requirements, NSBF design drivers and payload support requirements, the implementation phase summary development plan, and a comparison of three-meter and two-meter gondola concepts

    The α\u3csup\u3eD\u3c/sup\u3e-Globin Gene Originated via Duplication of an Embryonic α-Like Globin Gene in the Ancestor of Tetrapod Vertebrates

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    Gene duplication is thought to play an important role in the co-option of existing protein functions to new physiological pathways. The globin superfamily of genes provides an excellent example of the kind of physiological versatility that can be attained through the functional and regulatory divergence of duplicated genes that encode different subunit polypeptides of the tetrameric hemoglobin protein. In contrast to prevailing views about the evolutionary history of the α-globin gene family, here we present phylogenetic evidence that the αA- and αD-globin genes are not the product of a single, tandem duplication of an ancestral globin gene with adult function in the common ancestor of extant birds, reptiles, and mammals. Instead, our analysis reveals that the αD-globin gene of amniote vertebrates arose via duplication of an embryonic α-like globin gene that predated the radiation of tetrapods. The important evolutionary implication is that the distinct biochemical properties of αD-hemoglobin (HbD) are not exclusively derived characters that can be attributed to a postduplication process of neofunctionalization. Rather, many of the distinct biochemical properties of HbD are retained ancestral characters that reflect the fact that the αD-globin gene arose via duplication of a gene that had a larval/embryonic function. These insights into the evolutionary origin of HbD illustrate how adaptive modifications of physiological pathways may result from the retention and opportunistic co-option of ancestral protein functions

    Early onset epilepsy and inherited metabolic disorders: Diagnosis and management

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    Epileptic encephalopathies presenting in early life present a diagnostic and therapeutic challenge. These disorders present with multiple seizure types that are treatment resistant and associated with significant abnormalities on electroencephalographic studies. The underlying etiology in many cases may be related to an inborn error of metabolism. Efforts to establish the specific diagnosis of a genetic defect or an inborn error of metabolism often results in requests for a vast array of biochemical and molecular tests leading to an expensive workup. In this review, we present the clinician with information that provides a rationale for a selective and nuanced approach to biochemical assays, and initial treatment strategies while waiting for a specific diagnosis to be established. A careful consideration of the presentation, identification of potentially treatable conditions, and consultation with the biochemical genetics laboratory can lead to a greater measure of success while limiting cost overruns. Such a targeted approach is hoped will lead to an early diagnosis and appropriate interventions

    Structure in the nucleus of NGC 1068 at 10 microns

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    New 8 to 13 micron array camera images of the central kiloparsec of Seyfert 2 galaxy NGC 1068 resolve structure that is similar to that observed at visible and radio wavelengths. The images reveal an infrared source which is extended and asymmetric, with its long axis oriented at P.A. 33 deg. Maps of the spatial distribution of 8 to 13 micron color temperature and warm dust opacity are derived from the multiwavelength infrared images. The results suggest that there exist two pointlike luminosity sources in the central regions of NGC 1068, with the brighter source at the nucleus and the fainter one some 100 pc to the northeast. This geometry strengthens the possibility that the 10 micron emission observed from grains in the nucleus is powered by a nonthermal source. In the context of earlier visible and radio studies, these results considerably strengthen the case for jet induced star formation in NGC 1068

    The 8.3 and 12.4 micron imaging of the Galactic Center source complex with the Goddard infrared array camera

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    A 30 x 30 arcsec field at the Galactic Center (1.5 x 1.5 parsec) was mapped at 8.3 microns and 12.41 microns with high spatial resolution and accurate relative astrometry, using the 16 x 16 Si:Bi accumulation mode charge injection device Goddard infrared array camera. The design and performance of the array camera detector electronics system and image data processing techniques are discussed. Color temperature and dust opacity distributions derived from the spatially accurate images indicate that the compact infrared sources and the large scale ridge structure are bounded by warmer, more diffuse material. None of the objects appear to be heated appreciably by internal luminosity sources. These results are consistent with the model proposing that the complex is heated externally by a strong luminosity source at the Galactic Center, which dominates the energetics of the inner few parsecs of the galaxy

    A novel technique for selective NF-kappa B inhibition in Kupffer cells: contrary effects in fulminant hepatitis and ischaemia-reperfusion.

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    Background and aims: The transcription factor nuclear factor kappa B (NF-kB) has risen as a promising target for anti-inflammatory therapeutics. In the liver, however, NFkB inhibition mediates both damaging and protective effects. The outcome is deemed to depend on the liver cell type addressed. Recent gene knock-out studies focused on the role of NF-kB in hepatocytes, whereas the role of NF-kB in Kupffer cells has not yet been investigated in vivo. Here we present a novel approach, which may be suitable for clinical application, to selectively target NF-kB in Kupffer cells and analyse the effects in experimental models of liver injury. Methods: NF-kB inhibiting decoy oligodeoxynucleotides were loaded upon gelatin nanoparticles (D-NPs) and their in vivo distribution was determined by confocal microscopy. Liver damage, NF-kB activity, cytokine levels and apoptotic protein expression were evaluated after lipopolysaccharide (LPS), D-galactosamine (GalN)/LPS, or concanavalin A (ConA) challenge and partial warm ischaemia and subsequent reperfusion, respectively. Results: D-NPs were selectively taken up by Kupffer cells and inhibited NF-kB activation. Inhibition of NF-kB in Kupffer cells improved survival and reduced liver injury after GalN/LPS as well as after ConA challenge. While anti-apoptotic protein expression in liver tissue was not reduced, pro-apoptotic players such as cJun N-terminal kinase (JNK) were inhibited. In contrast, selective inhibition of NF-kB augmented reperfusion injury. Conclusions: NF-kB inhibiting decoy oligodeoxynucleotide- loaded gelatin nanoparticles is a novel tool to selectively inhibit NF-kB activation in Kupffer cells in vivo. Thus, liver injury can be reduced in experimental fulminant hepatitis, but increased at ischaemia–reperfusion

    Detection and quantification of inverse spin Hall effect from spin pumping in permalloy/normal metal bilayers

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    Spin pumping is a mechanism that generates spin currents from ferromagnetic resonance (FMR) over macroscopic interfacial areas, thereby enabling sensitive detection of the inverse spin Hall effect that transforms spin into charge currents in non-magnetic conductors. Here we study the spin-pumping-induced voltages due to the inverse spin Hall effect in permalloy/normal metal bilayers integrated into coplanar waveguides for different normal metals and as a function of angle of the applied magnetic field direction, as well as microwave frequency and power. We find good agreement between experimental data and a theoretical model that includes contributions from anisotropic magnetoresistance (AMR) and inverse spin Hall effect (ISHE). The analysis provides consistent results over a wide range of experimental conditions as long as the precise magnetization trajectory is taken into account. The spin Hall angles for Pt, Pd, Au and Mo were determined with high precision to be 0.013±0.0020.013\pm0.002, 0.0064±0.0010.0064\pm0.001, 0.0035±0.00030.0035\pm0.0003 and 0.0005±0.0001-0.0005\pm0.0001, respectively.Comment: 11 page
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