Comment on ``Passage Times for Unbiased Polymer Translocation through a Narrow Pore''

One of the most fundamental quantities associated with polymer translocation through a nanopore is the translocation time $\tau$ and its dependence on the chain length $N$. Our simulation results based on both the bond fluctuation Monte Carlo and Molecular Dynamics methods confirm the original prediction $\tau\sim N^{2\nu+1}$, which scales in the same manner as the Rouse relaxation time of the chain except for a larger prefactor, and invalidates other scaling claims.Comment: 1+pages, 1 Figure, Minor change

Polymer translocation through a nanopore: a two-dimensional Monte Carlo simulation

We investigate the problem of polymer translocation through a nanopore in the absence of an external driving force. To this end, we use the two-dimensional (2D) fluctuating bond model with single-segment Monte Carlo moves. To overcome the entropic barrier without artificial restrictions, we consider a polymer which is initially placed in the middle of the pore, and study the escape time required for the polymer to completely exit the pore on either end. In particular, we examined the effect of the pore length on the escape time.Comment: 16Pages, 6 figure

The first archaic Homo from Taiwan

Recent studies of an increasing number of hominin fossils highlight regional and chronological diversities of archaic Homo in the Pleistocene of eastern Asia. However, such a realization is still based on limited geographical occurrences mainly from Indonesia, China and Russian Altai. Here we describe a newly discovered archaic Homo mandible from Taiwan (Penghu 1), which further increases the diversity of Pleistocene Asian hominins. Penghu 1 revealed an unexpectedly late survival (younger than 450 but most likely 190-10 thousand years ago) of robust, apparently primitive dentognathic morphology in the periphery of the continent, which is unknown among the penecontemporaneous fossil records from other regions of Asia except for the mid-Middle Pleistocene Homo from Hexian, Eastern China. Such patterns of geographic trait distribution cannot be simply explained by clinal geographic variation of Homo erectus between northern China and Java, and suggests survival of multiple evolutionary lineages among archaic hominins before the arrival of modern humans in the region.This study was supported by grants from the Ministry of Science and Technology, Taiwan (102-2116-M-178-004-) to C.-H.C., the Japan Society for the Promotion of Science (No. 24247044) to Y.K., and Australian Research Council (DP110101415) to R.G

A Potential Galaxy Threshing System in the Cosmos Field

We report on the discovery of a new potential galaxy threshing system in the COSMOS 2 square degree field using the prime-focus camera, Suprime-Cam, on the 8.2 m Subaru Telescope. This system consists of a giant elliptical galaxy with $M_V \approx -21.6$ and a tidally disrupted satellite galaxy with $M_V \approx -17.7$ at a photometric redshift of $z \approx 0.08$. This redshift is consistent with the spectroscopic redshift of 0.079 for the giant elliptical galaxy obtained from the Sloan Digital Sky Survey (SDSS) archive. The luminosity masses of the two galaxies are $3.7 \times 10^{12} \cal{M}_{\odot}$ and $3.1 \times 10^{9} \cal{M}_{\odot}$, respectively. The distance between the two galaxies is greater than 100 kpc. The two tidal tails emanating from the satellite galaxy extend over 150 kpc. This system would be the second well-defined galaxy threshing system found so far.Comment: 17 pages, 7 figures, accepted for the COSMOS special issue of ApJ

High-Angular Resolution Dust Polarization Measurements: Shaped B-field Lines in the Massive Star Forming Region Orion BN/KL

We present observational results of the thermal dust continuum emission and its linear polarization in one of the nearest massive star-forming sites Orion BN/KL in Orion Molecular Cloud-1. The observations were carried out with the Submillimeter Array. With an angular resolution of 1" (~2 mpc; 480 AU), we have detected and resolved the densest cores near the BN/KL region. At a wavelength of ~870 micron, the polarized dust emission can be used to trace the structure of the magnetic field in this star-forming core. The dust continuum appears to arise from a V-shaped region, with a cavity nearly coincident with the center of the explosive outflows observed on larger scales. The position angles (P.A.s) of the observed polarization vary significantly by a total of about 90 degree but smoothly, i.e., curl-like, across the dust ridges. Such a polarization pattern can be explained with dust grains being magnetically aligned instead of mechanically with outflows, since the latter mechanism would cause the P.A.s to be parallel to the direction of the outflow, i.e., radial-like. The magnetic field projected in the plane of sky is therefore derived by rotating the P.A.s of the polarization by 90 degree. We find an azimuthally symmetric structure in the overall magnetic field morphology, with the field directions pointing toward 2.5" west to the center of the explosive outflows. We also find a preferred symmetry plane at a P.A. of 36 degree, which is perpendicular to the mean magnetic field direction (120 degree) of the 0.5 pc dust ridge. Two possible interpretations of the origin of the observed magnetic field structure are discussed.Comment: 27 pages, 7 figures; ApJ in pres

Spectroscopy of i-Dropout Galaxies with an NB921-Band Depression in the Subaru Deep Field

We report new spectroscopy of two star-forming galaxies with strong Ly_alpha emission at z=6.03 and z=6.04 in the Subaru Deep Field. These two objects are originally selected as i'-dropouts (i'-z' > 1.5) showing an interesting photometric property, the ``NB921 depression''. The NB921-band (centered at 9196A) magnitude is significantly depressed with respect to the z'-band magnitude. The optical spectra of these two objects exhibit asymmetric emission-lines at lambda_obs ~ 8540A and ~ 8560A, suggesting that these objects are Ly_alpha emitters at z~6. The rest-frame equivalent widths of the Ly_alpha emission of the two objects are 94A and 236A; the latter one is the Ly_alpha emitter with the largest Ly_alpha equivalent width at z > 6 ever spectroscopically confirmed. The spectroscopically measured Ly_alpha fluxes of these two objects are consistent with the interpretation that the NB921 depression is caused by the contribution of the strong Ly_alpha emission to the z'-band flux. Most of the NB921-depressed i'-dropout objects are thought to be strong Ly_alpha emitters at 6.0 < z < 6.5; Galactic L and T dwarfs and NB921-dropout galaxies at z > 6.6 do not dominate the NB921-depressed i'-dropout sample. Thus the NB921-depression method is very useful for finding high-z Ly_alpha emitters with a large Ly_alpha equivalent width over a large redshift range, 6.0 < z < 6.5. Although the broadband-selected sample at z ~ 3 contains only a small fraction of objects with a Ly_alpha equivalent width larger than 100A, the i'-dropout sample of the Subaru Deep Field contains a much larger fraction of such strong Ly_alpha emitters. This may imply a strong evolution of the Ly_alpha equivalent width from z > 6 to z ~ 3.Comment: 21 pages, 6 figures, to appear in The Astrophysical Journa

Hot and Diffuse Clouds near the Galactic Center Probed by Metastable H3+

Using an absorption line from the metastable (J, K) = (3, 3) level of H3+ together with other lines of H3+ and CO observed along several sightlines, we have discovered a vast amount of high temperature (T ~ 250 K) and low density (n ~ 100 cm-3) gas with a large velocity dispersion in the Central Molecular Zone (CMZ) of the Galaxy, i.e., within 200 pc of the center. Approximately three fourths of the H3+ along the line of sight to the brightest source we observed, the Quintuplet object GCS 3-2, is inferred to be in the CMZ, with the remaining H3+ located in intervening spiral arms. About half of H3+ in the CMZ has velocities near ~ - 100 km s-1 indicating that it is associated with the 180 pc radius Expanding Molecular Ring which approximately forms outer boundary of the CMZ. The other half, with velocities of ~ - 50 km s-1 and ~ 0 km s-1, is probably closer to the center. CO is not very abundant in those clouds. Hot and diffuse gas in which the (3, 3) level is populated was not detected toward several dense clouds and diffuse clouds in the Galactic disk where large column densities of colder H3+ have been reported previously. Thus the newly discovered environment appears to be unique to the CMZ. The large observed H3+ column densities in the CMZ suggests an ionization rate much higher than in the diffuse interstellar medium in the Galactic disk. Our finding that the H3+ in the CMZ is almost entirely in diffuse clouds indicates that the reported volume filling factor (f &#8805; 0.1) for n &#8805; 104 cm-3 clouds in the CMZ is an overestimate by at least an order of magnitude.Comment: 33 pages, 5 figures, 3 table

Large Scale Flows from Orion-South

Multiple optical outflows are known to exist in the vicinity of the active star formation region called Orion-South (Orion-S). We have mapped the velocity of low ionization features in the brightest part of the Orion Nebula, including Orion-S, and imaged the entire nebula with the Hubble Space Telescope. These new data, combined with recent high resolution radio maps of outflows from the Orion-S region, allow us to trace the origin of the optical outflows. It is confirmed that HH 625 arises from the blueshifted lobe of the CO outflow from 136-359 in Orion-S while it is likely that HH 507 arises from the blueshifted lobe of the SiO outflow from the nearby source 135-356. It is likely that redshifted lobes are deflected within the photon dominated region behind the optical nebula. This leads to a possible identification of a new large shock to the southwest from Orion-S as being driven by the redshifted CO outflow arising from 137-408. The distant object HH 400 is seen to have two even further components and these all are probably linked to either HH 203, HH 204, or HH 528. Distant shocks on the west side of the nebula may be related to HH 269. The sources of multiple bright blueshifted Herbig-Haro objects (HH 202, HH 203, HH 204, HH 269, HH 528) remain unidentified, in spite of earlier claimed identifications. Some of this lack of identification may arise from the fact that deflection in radial velocity can also produce a change in direction in the plane of the sky. The best way to resolve this open question is through improved tangential velocities of low ionization features arising where the outflows first break out into the ionized nebula.Comment: Astronomical Journal, in press. Some figures are shown at reduced resolution. A full-resolution version is available at http://ifront.org/wiki/Orion_South_Outflows_Pape

The Subaru COSMOS 20: Subaru Optical Imaging of the HST COSMOS Field with 20 Filters

We present both the observations and the data reduction procedures of the Subaru COSMOS 20 project that is an optical imaging survey of the HST COSMOS field, carried out by using Suprime-Cam on the Subaru Telescope with the following 20 optical filters: 6 broad-band (B, g', V, r', i', and z'), 2 narrow-band (NB711 and NB816), and 12 intermediate-band filters (IA427, IA464, IA484, IA505, IA527, IA574, IA624, IA679, IA709, IA738, IA767, and IA827). A part of this project is described in Taniguchi et al. (2007) and Capak et al. (2007) for the six broad-band and one narrow-band (NB816) filter data. In this paper, we present details of the observations and data reduction for remaining 13 filters (the 12 IA filters and NB711). In particular, we describe the accuracy of both photometry and astrometry in all the filter bands. We also present optical properties of the Suprime-Cam IA filter system in Appendix.Comment: 15 pages, 8 figures, 7 tables; accepted for publication in PASJ on October 2, 201