15,167 research outputs found
First Canadian Record of \u3ci\u3eHexacola Neoscatellae\u3c/i\u3e (Hymenoptera: Figitidae: Eucoilinae), A Parasitoid of the Shore Fly, \u3ci\u3eScatella Stagnalis\u3c/i\u3e
This paper documents the first occurrence of Hexacola neoscatellae, a shore fly parasitoid, in Canada. The discovery of H. neoscatellae is significant because currently there are no suitable biological control agents available for shore fly control to the floriculture industry
The opposites task: Using general rules to test cognitive flexibility in preschoolers
A brief narrative description of the journal article, document, or resource. Executive functions play an important role in cognitive development, and during the preschool years especially, children's performance is limited in tasks that demand flexibility in their behavior. We asked whether preschoolers would exhibit limitations when they are required to apply a general rule in the context of novel stimuli on every trial (the "opposites" task). Two types of inhibitory processing were measured: response interference (resistance to interference from a competing response) and proactive interference (resistance to interference from a previously relevant rule). Group data show 3-year-olds have difficulty inhibiting prepotent tendencies under these conditions, whereas 5-year-olds' accuracy is near ceiling in the task. (Contains 4 footnotes and 1 table.
Collateral and Debt Maturity Choice. A Signaling Model
This paper derives optimal loan policies under asymmetric information where banks offer loan contracts of long and short duration, backed or unbacked with collateral. The main novelty of the paper is that it analyzes a setting in which high quality firms use collateral as a complementary device along with debt maturity to signal their superiority. The least-cost signaling equilibrium depends on the relative costs of the signaling devices, the difference in firm quality and the proportion of good firms in the market. Model simulations suggest a non-monotonic relationship between firm quality and debt maturity, in which high quality firms have both long-term secured debt and short-term secured or non-secured debt.
Integral-Field Spectroscopy of the Post Red Supergiant IRC +10420: evidence for an axi-symmetric wind
We present NAOMI/OASIS adaptive-optics assisted integral-field spectroscopy
of the transitional massive hypergiant IRC +10420, an extreme mass-losing star
apparently in the process of evolving from a Red Supergiant toward the
Wolf-Rayet phase. To investigate the present-day mass-loss geometry of the
star, we study the appearance of the line-emission from the inner wind as
viewed when reflected off the surrounding nebula. We find that, contrary to
previous work, there is strong evidence for wind axi-symmetry, based on the
equivalent-width and velocity variations of H and Fe {\sc ii}
6516. We attribute this behaviour to the appearance of the complex
line-profiles when viewed from different angles. We also speculate that the Ti
{\sc ii} emission originates in the outer nebula in a region analogous to the
Strontium Filament of Carinae, based on the morphology of the
line-emission. Finally, we suggest that the present-day axisymmetric wind of
IRC +10420, combined with its continued blueward evolution, is evidence that
the star is evolving toward the B[e] supergiant phase.Comment: 22 pages, 9 figures, accepted for publication in ApJ. B&W-optimized
version can be downloaded from http://www.cis.rit.edu/~bxdpci/pubs.htm
Microstructure of the Local Interstellar Cloud and the Identification of the Hyades Cloud
We analyze high-resolution UV spectra of the Mg II h and k lines for 18
members of the Hyades Cluster to study inhomogeneity along these proximate
lines of sight. The observations were taken by the Space Telescope Imaging
Spectrograph (STIS) instrument on board the Hubble Space Telescope (HST). Three
distinct velocity components are observed. All 18 lines of sight show
absorption by the Local Interstellar Cloud (LIC), ten stars show absorption by
an additional cloud, which we name the Hyades Cloud, and one star exhibits a
third absorption component. The LIC absorption is observed at a lower radial
velocity than predicted by the LIC velocity vector derived by Lallement &
Bertin (1992) and Lallement et al. (1995), (v(predicted LIC) - v(observed LIC)
= 2.9 +/- 0.7 km/s), which may indicate a compression or deceleration at the
leading edge of the LIC. We propose an extention of the Hyades Cloud boundary
based on previous HST observations of other stars in the general vicinity of
the Hyades, as well as ground-based Ca II observations. We present our fits of
the interstellar parameters for each absorption component. The availability of
18 similar lines of sight provides an excellent opportunity to study the
inhomogeneity of the warm, partially ionized local interstellar medium (LISM).
We find that these structures are roughly homogeneous. The measured Mg II
column densities do not vary by more than a factor of 2 for angular separations
of < 8 degrees, which at the outer edge of the LIC correspond to physical
separations of < 0.6 pc.Comment: 35 pages, 11 figures, AASTEX v.5.0 plus EPSF extensions in mkfig.sty;
accepted by Ap
Axial Symmetry and Rotation in the SiO Maser Shell of IK Tauri
We observed v=1, J=1-0 43-GHz SiO maser emission toward the Mira variable IK
Tauri (IK Tau) using the Very Long Baseline Array (VLBA). The images resulting
from these observations show that SiO masers form a highly elliptical ring of
emission approximately 58 x 32 mas with an axial ratio of 1.8:1. The major axis
of this elliptical distribution is oriented at position angle of ~59 deg. The
line-of-sight velocity structure of the SiO masers has an apparent axis of
symmetry consistent with the elongation axis of the maser distribution.
Relative to the assumed stellar velocity of 35 km/s, the blue- and red-shifted
masers were found to lie to the northwest and southeast of this symmetry axis
respectively. This velocity structure suggests a NW-SE rotation of the SiO
maser shell with an equatorial velocity, which we determine to be ~3.6 km/s.
Such a NW-SE rotation is in agreement with a circumstellar envelope geometry
invoked to explain previous water and OH maser observations. In this geometry,
water and OH masers are preferentially created in a region of enhanced density
along the NE-SW equator orthogonal to the rotation/polar axis suggested by the
SiO maser velocities.Comment: 17 Pages, 4 figures (2 color); accepted for publication in Ap
Consumer credit information systems: A critical review of the literature. Too little attention paid by lawyers?
This paper reviews the existing literature on consumer credit reporting, the most extensively used instrument to overcome information asymmetry and adverse selection problems in credit markets. Despite the copious literature in economics and some research in regulatory policy, the legal community has paid almost no attention to the legal framework of consumer credit information systems, especially within the context of the European Union. Studies on the topic, however, seem particularly relevant in view of the establishment of a single market for consumer credit. This article ultimately calls for further legal research to address consumer protection concerns and inform future legislation
Violent quenching : Molecular Gas Blown to 1000 km s -1 during a Major Merger
Accepted for publication in ApJ LettersWe present Atacama Large Millimeter/submillimeter Array observations of a massive () compact ( pc) merger remnant at z = 0.66 that is driving a 1000 km s -1 outflow of cool gas, with no observational trace of an active galactic nucleus (AGN). We resolve molecular gas on scales of approximately 1-2 kpc, and our main finding is the discovery of a wing of blueshifted CO J(2 â 1) emission out to-1000 km s -1 relative to the stars. We argue that this is the molecular component of a multiphase outflow, expelled from the central starburst within the past 5 Myr through stellar feedback, although we cannot rule out previous AGN activity as a launching mechanism. If the latter is true, then this is an example of a relic multiphase AGN outflow. We estimate a molecular mass outflow rate of approximately 300 M o yr -1, or about one third of the 10 Myr-Averaged star formation rate. This system epitomizes the multiphase "blowout" episode following a dissipational major merger-a process that has violently quenched central star formation and supermassive black hole growth.Peer reviewedFinal Accepted Versio
- âŠ