563 research outputs found
Whales, dolphins, and porpoises of the western North Atlantic: a guide to their identification
This is an identification guide for cetaceans (whales, dolphins, and porpoises). It was designed to assist laypersons in identifying cetaceans encountered in the western North Atlantic Ocean and was intended for use by ongoing cetacean observer programs. This publication includes sections on identifying cetaceans at sea as well as stranded animals on shore. Species accounts are divided by body size and presence or lack of a dorsal fin. Appendices cover tags used on cetacean species; how to record and report cetacean observations at see and for stranded cetaceans; and a list of contacts for reporting cetacean strandings. (Document pdf contains 183 pages - file takes considerable time to open
Soil replacement depth and deep ripping to reclaim surface-mined land
Call number: LD2668 .T4 AGRN 1989 C35Master of ScienceAgronom
Spectroscopy of Giant Stars in the Pyxis Globular Cluster
The Pyxis globular cluster is a recently discovered globular cluster that
lies in the outer halo (R_{gc} ~ 40 kpc) of the Milky Way. Pyxis lies along one
of the proposed orbital planes of the Large Magellanic Cloud (LMC), and it has
been proposed to be a detached LMC globular cluster captured by the Milky Way.
We present the first measurement of the radial velocity of the Pyxis globular
cluster based on spectra of six Pyxis giant stars. The mean heliocentric radial
velocity is ~ 36 km/sec, and the corresponding velocity of Pyxis with respect
to a stationary observer at the position of the Sun is ~ -191 km/sec. This
radial velocity is a large enough fraction of the cluster's expected total
space velocity, assuming that it is bound to the Milky Way, that it allows
strict limits to be placed on the range of permissible transverse velocities
that Pyxis could have in the case that it still shares or nearly shares an
orbital pole with the LMC. We can rule out that Pyxis is on a near circular
orbit if it is Magellanic debris, but we cannot rule out an eccentric orbit
associated with the LMC. We have calculated the range of allowed proper motions
for the Pyxis globular cluster that result in the cluster having an orbital
pole within 15 degrees of the present orbital pole of the LMC and that are
consistent with our measured radial velocity, but verification of the tidal
capture hypothesis must await proper motion measurement from the Space
Interferometry Mission or HST. A spectroscopic metallicity estimate of [Fe/H] =
-1.4 +/- 0.1 is determined for Pyxis from several spectra of its brightest
giant; this is consistent with photometric determinations of the cluster
metallicity from isochrone fitting.Comment: 22 pages, 5 figures, aaspp4 style, accepted for publication in
October, 2000 issue of the PAS
Escape responses of cryptic frogs (Anura: Brachycephalidae: Craugastor) to simulated terrestrial and aerial predators
Summary Cryptic prey may increase likelihood of being detected if they move. When approached by predators, they must assess probabilities of survival if they remain immobile or attempt escape. Probability of survival is the joint probability of being detected, attacked if detected, and captured if attacked. We studied escape responses of several species of cryptic Craugastor (= Eleutherodactylus) frogs to simulated ground and aerial predators by varying elevation angle of attack. Frogs were predicted to escape more frequently when attacked from higher angles because a predator attacking from above on a trajectory leading directly to the prey is more likely to have detected and be attacking than a predator approaching directly, but horizontally. Frogs approached horizontally rarely jumped. The proportion of frogs that jumped increased as attack angle increased, and the proportion that turned or twitched was greatest for 45 • approaches. Distance jumped did not vary among attack angles. Escape was directed away from the object approaching at 45 • , but was random with respect to the frog's orientation during vertical approaches. Variation in escape tendency may occur because risk increases as attack angle increases, possibly because risk of being detected from above is greater and/or aerial predators are more efficient
Lunar Lander Offloading Operations Using a Heavy-Lift Lunar Surface Manipulator System
This study investigates the feasibility of using a heavy-lift variant of the Lunar Surface Manipulator System (LSMS-H) to lift and handle a 12 metric ton payload. Design challenges and requirements particular to handling heavy cargo were examined. Differences between the previously developed first-generation LSMS and the heavy-lift version are highlighted. An in-depth evaluation of the tip-over risk during LSMS-H operations has been conducted using the Synergistic Engineering Environment and potential methods to mitigate that risk are identified. The study investigated three specific offloading scenarios pertinent to current Lunar Campaign studies. The first involved offloading a large element, such as a habitat or logistics module, onto a mobility chassis with a lander-mounted LSMS-H and offloading that payload from the chassis onto the lunar surface with a surface-mounted LSMS-H. The second scenario involved offloading small pressurized rovers with a lander-mounted LSMS-H. The third scenario involved offloading cargo from a third-party lander, such as the proposed ESA cargo lander, with a chassis-mounted LSMS-H. In all cases, the analyses show that the LSMS-H can perform the required operations safely. However, Chariot-mounted operations require the addition of stabilizing outriggers, and when operating from the Lunar surface, LSMS-H functionality is enhanced by adding a simple ground anchoring system
A Second Giant Planet in 3:2 Mean-Motion Resonance in the HD 204313 System
We present 8 years of high-precision radial velocity (RV) data for HD 204313
from the 2.7 m Harlan J. Smith Telescope at McDonald Observatory. The star is
known to have a giant planet (M sin i = 3.5 M_J) on a ~1900-day orbit, and a
Neptune-mass planet at 0.2 AU. Using our own data in combination with the
published CORALIE RVs of Segransan et al. (2010), we discover an outer Jovian
(M sin i = 1.6 M_J) planet with P ~ 2800 days. Our orbital fit suggests the
planets are in a 3:2 mean motion resonance, which would potentially affect
their stability. We perform a detailed stability analysis, and verify the
planets must be in resonance.Comment: Accepted for publication in Ap
Planetary Candidates Observed by Kepler IV: Planet Sample From Q1-Q8 (22 Months)
We provide updates to the Kepler planet candidate sample based upon nearly
two years of high-precision photometry (i.e., Q1-Q8). From an initial list of
nearly 13,400 Threshold Crossing Events (TCEs), 480 new host stars are
identified from their flux time series as consistent with hosting transiting
planets. Potential transit signals are subjected to further analysis using the
pixel-level data, which allows background eclipsing binaries to be identified
through small image position shifts during transit. We also re-evaluate Kepler
Objects of Interest (KOI) 1-1609, which were identified early in the mission,
using substantially more data to test for background false positives and to
find additional multiple systems. Combining the new and previous KOI samples,
we provide updated parameters for 2,738 Kepler planet candidates distributed
across 2,017 host stars. From the combined Kepler planet candidates, 472 are
new from the Q1-Q8 data examined in this study. The new Kepler planet
candidates represent ~40% of the sample with Rp~1 Rearth and represent ~40% of
the low equilibrium temperature (Teq<300 K) sample. We review the known biases
in the current sample of Kepler planet candidates relevant to evaluating planet
population statistics with the current Kepler planet candidate sample.Comment: 12 pages, 8 figures, Accepted ApJ Supplemen
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