2,537 research outputs found
Implications and Considerations Concerning the Status, Habitat and Distribution of the Least Brook Lamprey, Lampetra aepyptera (Abbott) (Pisces: Petromyzontidae) in Arkansas
Fishes of Rock Creek, Sharp County, Arkansas
A survey of the fishes of Rock Creek in north central Arkansas was made on 9-10 November, 1978, and 15-16 March, 1979. Field collections were made using a minnow seine and backpack shocker. The creek system was inhabited by 28 species of fish representing eight families. Fish collections were typical of a small Ozark stream. The most abundant species were: Campostoma oligolepis Hubbs and Greene, largescale stoneroller; Notropis telescopus (Cope), telescope shiner; Notropis zonatus (Putnam), bleeding shiner; Moxostoma duquesnei (Lesueur), black redhorse; Etheostoma blennioides Rafinesque, greenside darter; Etheostoma caeruleum Storer, rainbow darter; Etheostoma euzonum (Hubbs and Black), Arkansas saddled darter; Etheostoma spectabile (Agassiz), orangethroat darter; and Cottus bairdi Girard, mottled sculpin. Lampetra aepyptera (Abbott), least brook lamprey, represented an extension of the previously known range of this species in the state
Guidance for State Educational Authorities and Licensing Entities Regarding Online Certification to Work with Students with Disabilities
IDEAlly Prepared: Working Toward Special Education Teacher Preparation for Online Instruction
Northern JHK Standard Stars for Array Detectors
We report J, H and K photometry of 86 stars in 40 fields in the northern
hemisphere. The fields are smaller than or comparable to a 4x4 arcmin
field-of-view, and are roughly uniformly distributed over the sky, making them
suitable for a homogeneous broadband calibration network for near-infrared
panoramic detectors. K magnitudes range from 8.5 to 14, and J-K colors from
-0.1 to 1.2. The photometry is derived from a total of 3899 reduced images;
each star has been measured, on average, 26.0 times per filter on 5.5 nights.
Typical errors on the photometry are about 0.012.Comment: 10 pages including 3 figures, one separate figure on four pages. The
finding chart of the AS-30 field and a few coordinates have been corrected.
GIF finding charts can also be found at
http://www.arcetri.astro.it/~hunt/std.htm
Maximal Acceleration Is Nonrotating
In a stationary axisymmetric spacetime, the angular velocity of a stationary
observer that Fermi-Walker transports its acceleration vector is also the
angular velocity that locally extremizes the magnitude of the acceleration of
such an observer, and conversely if the spacetime is also symmetric under
reversing both t and phi together. Thus a congruence of Nonrotating
Acceleration Worldlines (NAW) is equivalent to a Stationary Congruence
Accelerating Locally Extremely (SCALE). These congruences are defined
completely locally, unlike the case of Zero Angular Momentum Observers (ZAMOs),
which requires knowledge around a symmetry axis. The SCALE subcase of a
Stationary Congruence Accelerating Maximally (SCAM) is made up of stationary
worldlines that may be considered to be locally most nearly at rest in a
stationary axisymmetric gravitational field. Formulas for the angular velocity
and other properties of the SCALEs are given explicitly on a generalization of
an equatorial plane, infinitesimally near a symmetry axis, and in a slowly
rotating gravitational field, including the weak-field limit, where the SCAM is
shown to be counter-rotating relative to infinity. These formulas are evaluated
in particular detail for the Kerr-Newman metric. Various other congruences are
also defined, such as a Stationary Congruence Rotating at Minimum (SCRAM), and
Stationary Worldlines Accelerating Radially Maximally (SWARM), both of which
coincide with a SCAM on an equatorial plane of reflection symmetry.
Applications are also made to the gravitational fields of maximally rotating
stars, the Sun, and the Solar System.Comment: 64 pages, no figures, LaTeX, Sections 10 and 11 added with
applications to maximally rotating stellar models of Cook, Shapiro, and
Teukolsky and to the Sun and Solar System with recent data from Pijpers that
the Sun has angular momentum 1.80 x 10^{75} = 0.216 M^2 = 47 hectares = 116
acres (with 0.8% uncertainty) and quadrupole moment (2.18 x 10^{-7})MR^2 =
1.60 x 10^{14} m^3 = 3.7 x 10^{117} (with 3% uncertaity), accepted Feb. 27
for Classical and Quantum Gravit
Barriers to development and progression of women entrepreneurs in Pakistan
This article would help integration of women entrepreneurs into the mainstream economy in Pakistan.In Pakistan, women entrepreneurs do not enjoy the same opportunities as men due to a number of deep-rooted discriminatory socio-cultural values and traditions. Furthermore, these restrictions can be observed within the support mechanisms that exist to assist such fledgling businesswomen. The economic potential of female entrepreneurs is not being realised as they suffer from a lack of access to capital, land, business premises, information technology, training and agency assistance. Inherent attitudes of a patriarchal society, that men are superior to women and that women are best suited to be homemakers, create formidable challenges. Women also receive little encouragement from some male family members, resulting in limited spatial mobility and a dearth of social capital. The research suggests that in order to foster development, multi-agency cooperation is required. The media, educational policy makers and government agencies could combine to provide women with improved access to business development services and facilitate local, regional and national networks
On the gravitational, dilatonic and axionic radiative damping of cosmic strings
We study the radiation reaction on cosmic strings due to the emission of
dilatonic, gravitational and axionic waves. After verifying the (on average)
conservative nature of the time-symmetric self-interactions, we concentrate on
the finite radiation damping force associated with the half-retarded minus
half-advanced ``reactive'' fields. We revisit a recent proposal of using a
``local back reaction approximation'' for the reactive fields. Using
dimensional continuation as convenient technical tool, we find, contrary to
previous claims, that this proposal leads to antidamping in the case of the
axionic field, and to zero (integrated) damping in the case of the
gravitational field. One gets normal positive damping only in the case of the
dilatonic field. We propose to use a suitably modified version of the local
dilatonic radiation reaction as a substitute for the exact (non-local)
gravitational radiation reaction. The incorporation of such a local
approximation to gravitational radiation reaction should allow one to complete,
in a computationally non-intensive way, string network simulations and to give
better estimates of the amount and spectrum of gravitational radiation emitted
by a cosmologically evolving network of massive strings.Comment: 48 pages, RevTex, epsfig, 1 figure; clarification of the domain of
validity of the perturbative derivation of the string equations of motion,
and of their renormalizabilit
- …