6,622 research outputs found
Water Maser Emission from the Active Nucleus in M51
22 GHz water vapor `kilomaser' emission is reported from the central region
of the Whirlpool galaxy M 51 (NGC 5194). The red-shifted spectral features
(Vlsr ~ 560 km/s), flaring during most of the year 2000, originate from a
spatially unresolved maser spot of size < 30 mas (< 1.5 pc), displaced by < 250
mas from the nucleus. The data provide the first direct evidence for the
association of an H2O kilomaser with an active galactic nucleus (AGN). In early
2001, blue-shifted maser emission (Vlsr ~ 435 km/s) was also detected. Red- and
blue-shifted features bracket the systemic velocity asymmetrically. Within the
standard model of a rotating Keplerian torus, this may either suggest the
presence of a highly eccentric circumnuclear cloud or red- and blue-shifted
`high velocity' emission from a radially extended torus. Most consistent with
the measured H2O position is, however, an association of the red-shifted H2O
emission with the northern part of the bipolar radio jet. In this scenario, the
(weaker) northern jet is receding while the blue-shifted H2O emission is
associated with the approaching southern jet.Comment: 9 pages, 1 figur
Strongly Coupled Semi-Direct Mediation of Supersymmetry Breaking
Strongly coupled semi-direct gauge mediation models of supersymmetry breaking
through massive mediators with standard model charges are investigated by means
of composite degrees of freedom. Sizable mediation is realized to generate the
standard model gaugino masses for a small mediator mass without breaking the
standard model symmetries.Comment: 7 pages; v2: the model generalized, gaugino mass corrected; v3:
explanations expanded, references adde
Large-scale analysis of human alternative protein isoforms: pattern classification and correlation with subcellular localization signals
We investigated human alternative protein isoforms of >2600 genes based on full-length cDNA clones and SwissProt. We classified the isoforms and examined their co-occurrence for each gene. Further, we investigated potential relationships between these changes and differential subcellular localization. The two most abundant patterns were the one with different C-terminal regions and the one with an internal insertion, which together account for 43% of the total. Although changes of the N-terminal region are less common than those of the C-terminal region, extension of the C-terminal region is much less common than that of the N-terminal region, probably because of the difficulty of removing stop codons in one isoform. We also found that there are some frequently used combinations of co-occurrence in alternative isoforms. We interpret this as evidence that there is some structural relationship which produces a repertoire of isoformal patterns. Finally, many terminal changes are predicted to cause differential subcellular localization, especially in targeting either peroxisomes or mitochondria. Our study sheds new light on the enrichment of the human proteome through alternative splicing and related events. Our database of alternative protein isoforms is available through the internet
CO observations of galaxies with the Nobeyama 45-M telescope
High-resolution (15 inch), filled aperture maps of the CO (J = 1-0) line emission were obtained for several nearby, CO-bright galaxies like M82, M83, IC342, and NGC891 in order to study star forming activity in these galaxies
Enhanced low-energy spin dynamics with diffusive character in the iron-based superconductor (La0.87Ca0.13)FePO: Analogy with high Tc cuprates (A short note)
In a recent NMR investigation of the iron-based superconductor
(La0.87Ca0.13)FePO [Phys. Rev. Lett. 101, 077006 (2008)] Y. Nakai et al.
reported an anomalous behavior of the nuclear spin-lattice relaxation of 31P
nuclei in the superconducting state: The relaxation rate 1/T1 strongly depends
on the measurement frequency and its T dependence does not show the typical
decrease expected for the superconducting state. In this short note, we point
out that these two observations bear similarity with the situation is some of
the high Tc cuprates.Comment: To appear in J. Phys. Soc. Jpn. (Short Note
Titanium-Based Biomaterials for Preventing Stress Shielding between Implant Devices and Bone
β-type titanium alloys with low Young's modulus are required to inhibit bone atrophy and enhance bone remodeling for implants used to substitute failed hard tissue. At the same time, these titanium alloys are required to have high static and dynamic strength. On the other hand, metallic biomaterials with variable Young's modulus are required to satisfy the needs of both patients and surgeons, namely, low and high Young's moduli, respectively. In this paper, we have discussed effective methods to improve the static and dynamic strength while maintaining low Young's modulus for β-type titanium alloys used in biomedical applications. Then, the advantage of low Young's modulus of β-type titanium alloys in biomedical applications has been discussed from the perspective of inhibiting bone atrophy and enhancing bone remodeling. Further, we have discussed the development of β-type titanium alloys with a self-adjusting Young's modulus for use in removable implants
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