47,373 research outputs found
Food habits of Steller sea lions (Eumetopias jubatus) off Oregon and northern California, 1986–2007
We described the diet of the eastern stock of Steller sea lions (Eumetopias jubatus) from 1416 scat samples collected from five sites in Oregon and northern California from 1986 through 2007. A total of 47 prey types from 30 families were
identified. The most common prey was Pacific hake (Merluccius productus), followed by salmonids (Oncorhynchus
spp.), skates (Rajidae), Pacific lamprey (Lampetra tridentata), herrings (Clupeidae), rockfish (Sebastes spp.),
and northern anchovy (Engraulis mordax). Steller sea lion diet composition varied seasonally, annually, and spatially. Hake and salmonids were the most commonly identified prey in scats collected during the summer
(breeding season), whereas hake and skate were most common in the nonbreeding season. Continued research on Steller sea lion diet and foraging behavior in the southern extent of their range is necessary to address issues such as climate change, interaction with competing California sea
lions, and predation impacts on valuable or sensitive fish stocks
SEASONAL INCIDENCE OF CAPTURE AND REPRODUCTION OF FIVE FOSSORIAL SNAKE SPECIES IN WEST VIRGINIA
Museum specimens of five species of fossorial snakes collected in West Virginia during 1930–2000 were examined to determine monthly incidence of capture, adult body sizes, reproductive cycle, and clutch characteristics. Captures occurred over the shortest time in the year in the Eastern Earthsnake (Virginia valeriae valeriae) and Northern Red-bellied Snake (Storeria occipitomaculata occipitomaculata) and were longest in the Northern Brownsnake (S. dekayi dekayi). Male gonadal cycle conformed to the temperate pattern, whereas that of females tended towards a tropical pattern. Incidence of females nearing oviposition or parturition was highest during June–July for all species, and length of their reproductive seasons were generally in keeping with those of northerly populations of the respective species. Mean clutch sizes were largest in the Northern Brownsnake (mean = 20.5) and smallest in the single oviparous snake, the Eastern Wormsnake (mean = 2.8). Adult body sizes were similar to respective populations elsewhere within their ranges. The Mountain Earth Snake (V. pulchra) was the least represented species in this study. A meaningful degree of predictability existed in the life history traits examined in our study as they related to geographic trends of this Allegheny snake assemblage
Angular Power Spectrum of the Microwave Background Anisotropy seen by the COBE Differential Microwave Radiometer
The angular power spectrum estimator developed by Peebles (1973) and Hauser &
Peebles (1973) has been modified and applied to the 2 year maps produced by the
COBE DMR. The power spectrum of the real sky has been compared to the power
spectra of a large number of simulated random skies produced with noise equal
to the observed noise and primordial density fluctuation power spectra of power
law form, with . Within the limited range of spatial scales
covered by the COBE DMR, corresponding to spherical harmonic indices 3 \leq
\ell \lsim 30, the best fitting value of the spectral index is with the Harrison-Zeldovich value approximately
0.5 below the best fit. For 3 \leq \ell \lsim 19, the best fit is . Comparing the COBE DMR at small to
the at from degree scale anisotropy experiments
gives a smaller range of acceptable spectral indices which includes .Comment: 22 pages of LaTex using aaspp.sty and epsf.sty with appended
Postscript figures, COBE Preprint 94-0
Australian Economic History
In a time of pandemics, war and climate change, fostering knowledge that transcends disciplinary boundaries is more important than ever. Economic history is one of the world's oldest interdisciplinary fields, with its prosperity dependent on connection and relevance to disciplinary behemoths economics and history. Australian Economic History is the first history of an interdisciplinary field in Australia, and the first to set the field’s progress within the structures of Australian universities. It highlights the lived experience of doing interdisciplinary research, and how scholars have navigated the opportunities and challenges of this form of knowledge. These lessons are vital for those seeking to develop robust interdisciplinary conversations now and in the future
Infrared Emission from the Radio Supernebula in NGC 5253: A Proto-Globular Cluster?
Hidden from optical view in the starburst region of the dwarf galaxy NGC 5253
lies an intense radio source with an unusual spectrum which could be
interpreted variously as nebular gas ionized by a young stellar cluster or
nonthermal emission from a radio supernova or an AGN. We have obtained 11.7 and
18.7 micron images of this region at the Keck Telescope and find that it is an
extremely strong mid-infrared emitter. The infrared to radio flux ratio rules
out a supernova and is consistent with an HII region excited by a dense cluster
of young stars. This "super nebula" provides at least 15% of the total
bolometric luminosity of the galaxy. Its excitation requires 10^5-10^6 stars,
giving it the total mass and size (1-2 pc diameter) of a globular cluster.
However, its high obscuration, small size, and high gas density all argue that
it is very young, no more than a few hundred thousand years old. This may be
the youngest globular cluster yet observed.Comment: 6 pages, 2 color figures, Submitted to the ApJL, Revised 4/6/01 based
on referee's comment
ISOCAM spectro-imaging of the H2 rotational lines in the supernova remnant IC443
We report spectro-imaging observations of the bright western ridge of the
supernova remnant IC 443 obtained with the ISOCAM circular variable filter
(CVF) on board the Infrared Space Observatory (ISO). This ridge corresponds to
a location where the interaction between the blast wave of the supernova and
ambient molecular gas is amongst the strongest. The CVF data show that the 5 to
14 micron spectrum is dominated by the pure rotational lines of molecular
hydrogen (v = 0--0, S(2) to S(8) transitions). At all positions along the
ridge, the H2 rotational lines are very strong with typical line fluxes of
10^{-4} to 10^{-3} erg/sec/cm2/sr. We compare the data to a new time-dependent
shock model; the rotational line fluxes in IC 443 are reproduced within factors
of 2 for evolutionary times between 1,000 and 2,000 years with a shock velocity
of 30 km/sec and a pre-shock density of 10^4 /cm3.Comment: To appear in Astronomy and Astrophysic
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