釋“詩者天地之心”

漢儒自董仲舒起，改造戰國以來道家等諸子學説中的“天心”、“天地之心”等觀念，强調宇宙的道德稟性，又以儒家經典配合陰陽五行推算天道，占測天心，言説災異，“六經”遂轉爲政治數術。故《齊詩》與《詩緯》創言“詩者天地之心”，賦予《詩三百》以宇宙意義，又以“四始”、“五際”、“六情”之説，依孟京《易》學之例，以《詩三百》爲律曆，占知《詩》中之“天心”，推測風俗性情。“天心”、“天地之心”漸而流爲兩漢以降政治、學術、宗教之話語，至劉勰《文心雕龍》，以“天地之心”爲“道心”，建構“文心”之觀念，於文學形上學理論貢獻至大

Comparison of Gaia DR2 Parallaxes of Stars with VLBI Astrometry

We compare the parallaxes of stars from VLBI astrometry in the literature to those in the Gaia DR2 catalog. Our full sample contains young stellar objects, evolved AGB stars, pulsars and other radio stars. Excluding AGB stars, which show significant discrepancies between Gaia and VLBI parallaxes, and stars in binary systems, we obtain an average, systematic, parallax offset of $-75 \pm 29~\mu$as for Gaia DR2, consistent with their estimate of a parallax zero-point between $-100$ and 0 $\mu$as.Comment: Accepted by Ap

The Parallax of the Red Hypergiant VX Sgr with Accurate Tropospheric Delay Calibration

We report astrometric results of VLBI phase-referencing observations of 22 GHz \hho\ masers emission toward the red hypergiant \vxsgr, one of most massive and luminous red hypergiant stars in our Galaxy, using the Very Long Baseline Array. A background source, \Jtwoze, projected 4\d4 from the target \vxsgr, was used as the phase reference. For the low declinations of these sources, such a large separation normally would seriously degrade the relative astrometry. We use a two-step method of tropospheric delay calibration, which combines the VLBI geodetic-block (or GPS) calibration with an image-optimization calibration, to obtain a trigonometric parallax of $0.64\pm0.04$ mas, corresponding to a distance of 1.56$^{+0.11}_{-0.10}$ kpc. The measured proper motion of \vxsgr\ is $0.36\pm0.76$ and $-2.92\pm0.78$ \masy\ in the eastward and northward directions. The parallax and proper motion confirms that \vxsgr\ belong to the Sgr OB1 association. Rescaling bolometric luminosities in the literature to our parallax distance, we find the luminosity of \vxsgr~is $(1.95 \pm 0.62) \times 10^5$ \Lsun, where the uncertainty is dominated by differing photometry measurements.Comment: 16 pages, 10 figures, accepted by Ap

Parallaxes for star forming regions in the inner Perseus spiral arm

We report trigonometric parallax and proper motion measurements of 6.7-GHz CH3OH and 22-GHz H2O masers in eight high-mass star-forming regions (HMSFRs) based on VLBA observations as part of the BeSSeL Survey. The distances of these HMSFRs combined with their Galactic coordinates, radial velocities, and proper motions, allow us to assign them to a segment of the Perseus arm with ~< 70 deg. These HMSFRs are clustered in Galactic longitude from ~30 deg to ~50, neighboring a dirth of such sources between longitudes ~50 deg to ~90 deg.Comment: 18 pages, 4 figures, accepted for publication in The Astronomical Journal. arXiv admin note: text overlap with arXiv:1312.385

The parallax and 3D kinematics of water masers in the massive star-forming region G034.43+0.24

We report a trigonometric parallax measurement of 22 GHz water masers in the massive star-forming region G034.43+0.24 as part of the Bar and Spiral Structure Legacy (BeSSeL) Survey using the Very Long Baseline Array. The parallax is 0.330$\pm$50.018 mas, corresponding to a distance of $3.03^{+0.17}_{-0.16}$ kpc. This locates G034.43+0.24 near the inner edge of the Sagittarius spiral arm and at one end of a linear distribution of massive young stars which cross nearly the full width of the arm. The measured 3-dimensional motion of G034.43+0.24 indicates a near-circular Galactic orbit. The water masers display arc-like distributions, possibly bow shocks, associated with winds from one or more massive young stars

BEN domain protein Elba2 can functionally substitute for linker histone H1 in Drosophila in vivo

Metazoan linker histones are essential for development and play crucial roles in organization of chromatin, modification of epigenetic states and regulation of genetic activity. Vertebrates express multiple linker histone H1 isoforms, which may function redundantly. In contrast, H1 isoforms are not present in Dipterans, including D. melanogaster, except for an embryo-specific, distantly related dBigH1. Here we show that Drosophila BEN domain protein Elba2, which is expressed in early embryos and was hypothesized to have insulator-specific functions, can compensate for the loss of H1 in vivo. Although the Elba2 gene is not essential, its mutation causes a disruption of normal internucleosomal spacing of chromatin and reduced nuclear compaction in syncytial embryos. Elba2 protein is distributed ubiquitously in polytene chromosomes and strongly colocalizes with H1. In H1-depleted animals, ectopic expression of Elba2 rescues the increased lethality and ameliorates abnormalities of chromosome architecture and heterochromatin functions. We also demonstrate that ectopic expression of BigH1 similarly complements the deficiency of H1 protein. Thus, in organisms that do not express redundant H1 isoforms, the structural and biological functions performed by canonical linker histones in later development, may be shared in early embryos by weakly homologous proteins, such as BigH1, or even unrelated, non-homologous proteins, such as Elba2