990 research outputs found
Incubation Energetics of the Laysan Albatross
The energy expenditure of incubating and foraging Laysan Albatross (Diomedea immutabilis, mean body weight 3.07 kg) was estimated by means of the doubly-la- belled water technique. During incubation, the energy expenditure was similar to that of resting birds that were not incubating an egg. The energy expenditure of foraging albatross (2072 kJ/day) was 2.6 times that of resting birds. It was concluded that the energy expenditure of the tropical Laysan Albatross was not less than that of species foraging over cold, high-latitude oceans. An energy budget compiled for an incubating pair of albatross revealed that the energy expenditure of the female was greater than that of the male bird, during the incubation perio
The Star Formation History of NGC 6822
Images of five fields in the Local Group dwarf irregular galaxy NGC 6822
obtained with the {\it Hubble Space Telescope} in the F555W and F814W filters
are presented. Photometry for the stars in these images was extracted using the
Point-Spread-Function fitting program HSTPHOT/MULTIPHOT. The resulting
color-magnitude diagrams reach down to , a level well below the red
clump, and were used to solve quantitatively for the star formation history of
NGC 6822. Assuming that stars began forming in this galaxy from low-metallicity
gas and that there is little variation in the metallicity at each age, the
distribution of stars along the red giant branch is best fit with star
formation beginning in NGC 6822 12-15 Gyr ago. The best-fitting star formation
histories for the old and intermediate age stars are similar among the five
fields and show a constant or somewhat increasing star formation rate from 15
Gyr ago to the present except for a possible dip in the star formation rate
from 3 to 5 Gyr ago. The main differences among the five fields are in the
higher overall star formation rate per area in the bar fields as well as in the
ratio of the recent star formation rate to the average past rate. These
variations in the recent star formation rate imply that stars formed within the
past 0.6 Gyr are not spatially very well mixed throughout the galaxy.Comment: 47 pages, 28 Figures, accepted for publication in the Astronomical
Journa
The erythromycin breath test as a predictor of cyclosporine blood levels
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109915/1/cptclpt1990126.pd
Threshold configurations in the presence of Lorentz violating dispersion relations
A general characterization of lower and upper threshold configurations for
two particle reactions is determined under the assumptions that the single
particle dispersion relations E(p) are rotationally invariant and monotonic in
p, and that energy and momentum are conserved and additive for multiple
particles. It is found that at a threshold the final particle momenta are
always parallel and the initial momenta are always anti-parallel. The
occurrence of new phenomena not occurring in a Lorentz invariant setting, such
as upper thresholds and asymmetric pair production thresholds, is explained,
and an illustrative example is given.Comment: 5 pages, 3 figure
Lorentz violation at high energy: concepts, phenomena and astrophysical constraints
We consider here the possibility of quantum gravity induced violation of
Lorentz symmetry (LV). Even if suppressed by the inverse Planck mass such LV
can be tested by current experiments and astrophysical observations. We review
the effective field theory approach to describing LV, the issue of naturalness,
and many phenomena characteristic of LV. We discuss some of the current
observational bounds on LV, focusing mostly on those from high energy
astrophysics in the QED sector at order E/M_Planck. In this context we present
a number of new results which include the explicit computation of rates of the
most relevant LV processes, the derivation of a new photon decay constraint,
and modification of previous constraints taking proper account of the helicity
dependence of the LV parameters implied by effective field theory.Comment: v.1 56 pages, 3 figures, Invited article for Annals of Physics; v.2:
60 pages, 3 figures. Typos fixed, references added, minor editing for clarity
and accuracy; discussion of fermion pair emission added. To appear in January
2006 special issue of Annals of Physic
Nuclear Shell Model Calculations of Neutralino-Nucleus Cross Sections for Silicon 29 and Germanium 73
We present the results of detailed nuclear shell model calculations of the
spin-dependent elastic cross section for neutralinos scattering from \si29 and
\ge73. The calculations were performed in large model spaces which adequately
describe the configuration mixing in these two nuclei. As tests of the computed
nuclear wave functions, we have calculated several nuclear observables and
compared them with the measured values and found good agreement. In the limit
of zero momentum transfer, we find scattering matrix elements in agreement with
previous estimates for \si29 but significantly different than previous work for
\ge73. A modest quenching, in accord with shell model studies of other heavy
nuclei, has been included to bring agreement between the measured and
calculated values of the magnetic moment for \ge73. Even with this quenching,
the calculated scattering rate is roughly a factor of 2 higher than the best
previous estimates; without quenching, the rate is a factor of 4 higher. This
implies a higher sensitivity for germanium dark matter detectors. We also
investigate the role of finite momentum transfer upon the scattering response
for both nuclei and find that this can significantly change the expected rates.
We close with a brief discussion of the effects of some of the non-nuclear
uncertainties upon the matrix elements.Comment: 31 pages, figures avaiable on request, UCRL-JC-11408
The ecological footprint remains a misleading metric of global sustainability
Linus Blomqvist, Barry W. Brook, Erle C. Ellis, Peter M. Kareiva, Ted Nordhaus, Michael Shellenberge
TeV Astrophysics Constraints on Planck Scale Lorentz Violation
We analyze observational constraints from TeV astrophysics on Lorentz
violating nonlinear dispersion for photons and electrons without assuming any a
priori equality between the photon and electron parameters. The constraints
arise from thresholds for vacuum Cerenkov radiation, photon decay and
photo-production of electron-positron pairs. We show that the parameter plane
for cubic momentum terms in the dispersion relations is constrained to an order
unity region in Planck units. We find that the threshold configuration can
occur with an asymmetric distribution of momentum for pair creation, and with a
hard photon for vacuum Cerenkov radiation.Comment: 4 pages, RevTeX4, 1 figure. Some references and a footnote added,
improved discussion on the photon annihilation and GZK cutoff. Minor changes
of wording. Main results unchanged. Version to appear as a Rapid
Communication in PR
Prospectus, September 21, 1976
PC BOARD OF TRUSTEES OKS DEFICIT BUDGET; Anna Dearing of the LS testing lab: I enjoy it ; Write-ins dominate election, 1st Stu-Go meeting tommorow; PC news in brief: Sociological Association, First Meeting, Yea team!!!, Need some help?, Basketball tryouts; Women\u27s program sponsors : Antonia ; Improve reading at PC; Letters to the editor: The pins, Again..., And again?..., Oh no! not again?..., Give a Schmidt!!!, Where are the sports?; Editorial: Students are consumers; Quad fest featured music, magic; Counselors comply with Title IX; Prairie Festival set for Sunday; Louise Parker: \u27People are fun to watch\u27; Auditions today, tomorrow; Summer school in the Rockies; Drag races teach needed skills; 45 students attend: Marriott\u27s Great America attracts Parkland field trip; Ike\u27s opinion: Controversy continues: feedback on Dr. Richards; Uncle Bob: Slinging vegies is old tradition; Country crowd: Charlie and his fans; Mark Twain; Mediaseen: Carter and the media; Classifieds; Hoofers do \u27extremely well\u27 at UI; Women\u27s volleyball schedule; Locks and Dam 26 is subject of Oct. 12 debate; Know your athletes: \u27T\u27 Square keeps on running to own beat; Ten men: C-C members listed; Cobra\u27s Corner: Women\u27s volleyball improves; Cross Country Schedule 1976; Golfers fourth in tourney; Lose your nose?; Know your athletes: Kathy Kaler prepares for teaching; Linton wins Fast Fred; Fast Freddy\u27s Football Forecast; Games of September 25https://spark.parkland.edu/prospectus_1976/1011/thumbnail.jp
The WiggleZ Dark Energy Survey: the transition to large-scale cosmic homogeneity
We have made the largest-volume measurement to date of the transition to
large-scale homogeneity in the distribution of galaxies. We use the WiggleZ
survey, a spectroscopic survey of over 200,000 blue galaxies in a cosmic volume
of ~1 (Gpc/h)^3. A new method of defining the 'homogeneity scale' is presented,
which is more robust than methods previously used in the literature, and which
can be easily compared between different surveys. Due to the large cosmic depth
of WiggleZ (up to z=1) we are able to make the first measurement of the
transition to homogeneity over a range of cosmic epochs. The mean number of
galaxies N(<r) in spheres of comoving radius r is proportional to r^3 within
1%, or equivalently the fractal dimension of the sample is within 1% of D_2=3,
at radii larger than 71 \pm 8 Mpc/h at z~0.2, 70 \pm 5 Mpc/h at z~0.4, 81 \pm 5
Mpc/h at z~0.6, and 75 \pm 4 Mpc/h at z~0.8. We demonstrate the robustness of
our results against selection function effects, using a LCDM N-body simulation
and a suite of inhomogeneous fractal distributions. The results are in
excellent agreement with both the LCDM N-body simulation and an analytical LCDM
prediction. We can exclude a fractal distribution with fractal dimension below
D_2=2.97 on scales from ~80 Mpc/h up to the largest scales probed by our
measurement, ~300 Mpc/h, at 99.99% confidence.Comment: 21 pages, 16 figures, accepted for publication in MNRA
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