1,796 research outputs found
Migration of northern Yellowstone elk: implications of spatial structuring
Migration can enhance survival and recruitment of mammals by increasing access to higher-quality forage or reducing predation risk, or both. We used telemetry locations collected from 140 adult female elk during 2000â 2003 and 2007â2008 to identify factors influencing the migration of northern Yellowstone elk. Elk wintered in 2 semidistinct herd segments and migrated 10â140 km to at least 12 summer areas in Yellowstone National Park (YNP) and nearby areas of Montana. Spring migrations were delayed after winters with increased snow pack, with earlier migration in years with earlier vegetation green-up. Elk wintering at lower elevations outside YNP migrated an average of 13 days earlier than elk at higher elevations. The timing of autumn migrations varied annually, but elk left their summer ranges at about the same time regardless of elevation, wolf numbers, or distance to their wintering areas. Elk monitored for multiple years typically returned to the same summer (96% fidelity, n 5 52) and winter (61% fidelity, n 5 41) ranges. Elk that wintered at lower elevations in or near the northwestern portion of the park tended to summer in the western part of YNP (56%), and elk that wintered at higher elevations spent summer primarily in the eastern and northern parts of the park (82%). Elk did not grossly modify their migration timing, routes, or use areas after wolf restoration. Elk mortality was low during summer and migration (8 of 225 elk-summers). However, spatial segregation and differential mortality and recruitment between herd segments on the northern winter range apparently contributed to a higher proportion of the elk population wintering outside the northwestern portion of YNP and summering in the western portion of the park. This change could shift wolf spatial dynamics more outside YNP and increase the risk of transmission of brucellosis from elk to cattle north of the park
Migration of northern Yellowstone elk: implications of spatial structuring
Migration can enhance survival and recruitment of mammals by increasing access to higher-quality forage or reducing predation risk, or both. We used telemetry locations collected from 140 adult female elk during 2000â 2003 and 2007â2008 to identify factors influencing the migration of northern Yellowstone elk. Elk wintered in 2 semidistinct herd segments and migrated 10â140 km to at least 12 summer areas in Yellowstone National Park (YNP) and nearby areas of Montana. Spring migrations were delayed after winters with increased snow pack, with earlier migration in years with earlier vegetation green-up. Elk wintering at lower elevations outside YNP migrated an average of 13 days earlier than elk at higher elevations. The timing of autumn migrations varied annually, but elk left their summer ranges at about the same time regardless of elevation, wolf numbers, or distance to their wintering areas. Elk monitored for multiple years typically returned to the same summer (96% fidelity, n 5 52) and winter (61% fidelity, n 5 41) ranges. Elk that wintered at lower elevations in or near the northwestern portion of the park tended to summer in the western part of YNP (56%), and elk that wintered at higher elevations spent summer primarily in the eastern and northern parts of the park (82%). Elk did not grossly modify their migration timing, routes, or use areas after wolf restoration. Elk mortality was low during summer and migration (8 of 225 elk-summers). However, spatial segregation and differential mortality and recruitment between herd segments on the northern winter range apparently contributed to a higher proportion of the elk population wintering outside the northwestern portion of YNP and summering in the western portion of the park. This change could shift wolf spatial dynamics more outside YNP and increase the risk of transmission of brucellosis from elk to cattle north of the park
The Central Temperature of the Sun can be Measured via the Be Solar Neutrino Line
A precise test of the theory of stellar evolution can be performed by
measuring the difference in average energy between the neutrino line produced
by electron capture in the solar interior and the corresponding
neutrino line produced in a terrestrial laboratory. The high temperatures in
the center of the sun broaden the line asymmetrically, FWHM = 1.6~keV, and
cause an average energy shift of 1.3~keV. The width of the Be neutrino line
should be taken into account in calculations of vacuum neutrino oscillations.Comment: RevTeX file, 9 pages. For hardcopy with figure, send to
[email protected]. Institute for Advanced Study number AST 93/4
K-shell photoionization of ground-state Li-like boron ions [B]: Experiment and Theory
Absolute cross sections for the K-shell photoionization of ground-state
Li-like boron [B(1s2s S)] ions were measured by employing the
ion-photon merged-beams technique at the Advanced Light Source synchrotron
radiation facility. The energy ranges 197.5--200.5 eV, 201.9--202.1 eV of the
[1s(2s\,2p)P]P and [1s(2s\,2p)P] P
resonances, respectively, were investigated using resolving powers of up to
17\,600. The energy range of the experiments was extended to about 238.2 eV
yielding energies of the most prominent
[1s(2\,n)]P resonances with an absolute accuracy
of the order of 130 ppm. The natural linewidths of the [1s(2s\,2p)P]
P and [1s(2s\,2p)P] P resonances were measured
to be meV and meV, respectively, which compare
favourably with theoretical results of 4.40 meV and 30.53 meV determined using
an intermediate coupling R-matrix method.Comment: 6 figures and 2 table
Turbulent spectrum of the Earth's ozone field
The Total Ozone Mapping Spectrometer (TOMS) database is subjected to an
analysis in terms of the Karhunen-Loeve (KL) empirical eigenfunctions. The
concentration variance spectrum is transformed into a wavenumber spectrum, . In terms of wavenumber is shown to be in the
inverse cascade regime, in the enstrophy cascade regime with the
spectral {\it knee} at the wavenumber of barotropic instability.The spectrum is
related to known geophysical phenomena and shown to be consistent with physical
dimensional reasoning for the problem. The appropriate Reynolds number for the
phenomena is .Comment: RevTeX file, 4 pages, 4 postscript figures available upon request
from Richard Everson <[email protected]
Performance of the Space Telescope Imaging Spectrograph after SM4
On May 17, 2009, during the fourth EVA of SM4, astronauts Michael Good and Mike Massimino replaced the failed LVPS-2 circuit board on the Space Telescope Imaging Spectrograph (STIS), restoring this HST instrument to operation after a nearly 6 year hiatus. STIS after this 2009 repair operates in much the same way as it did during the 2001-2004 period of operations with the Side-2 electronics. Internal and external alignments of the instrument are similar to what they had been in 2004, and most changes in performance are modest. The STIS CCD detector continued to experience radiation damage during the hiatus in operations, leading to decreased charge transfer efficiency (CTE) and an increased number of hot pixels. The sensitivities for most modes are surprisingly close to what was expected from simple extrapolation of the 2003-2004 trends, although the echelle modes show somewhat more complex behavior. The biggest surprise was that the dark count rate for the NUV MAMA detector after SM4 has been much larger than had been expected; it is currently about 2.5 times bigger than it was in 2004 and is only slowly decreasing. We discuss how these changes will affect science with STIS now and in the future
How Well Do We (and Will We) Know Solar Neutrino Fluxes and Oscillation Parameters?
Assuming neutrino oscillations occur, the pp electron neutrino flux is
uncertain by at least a factor of two, the flux by a factor of
five, and the flux by a factor of forty-five. Calculations of the
expected results of future solar neutrino experiments (SuperKamiokande, SNO,
BOREXINO, ICARUS, HELLAZ, and HERON) are used to illustrate the extent to which
these experiments will restrict the range of the allowed neutrino mixing
parameters. We present an improved formulation of the ``luminosity constraint''
and show that at 95\% confidence limit this constraint establishes the best
available limits on the rate of creation of pp neutrinos in the solar interior
and provides the best upper limit to the neutrino flux.Comment: 37 pages, uuencoded Z-compressed postscript file (with figures);
Submitted to Physical Review
A geometrical 1% distance to the short-period binary Cepheid V1334 Cygni
This is the author accepted manuscript. The final version is available from IOP Publishing via the DOI in this record.Cepheid stars play a considerable role as extragalactic distances indicators, thanks to the simple
empirical relation between their pulsation period and their luminosity. They overlap with that of
secondary distance indicators, such as Type Ia supernovae, whose distance scale is tied to Cepheid
luminosities. However, the PeriodâLuminosity (P-L) relation still lacks a calibration to better than 5 %.
Using an original combination of interferometric astrometry with optical and ultraviolet spectroscopy,
we measured the geometrical distance d = 720.35±7.84 pc of the 3.33 d period Cepheid V1334 Cyg with
an unprecedented accuracy of ±1 %, providing the most accurate distance for a Cepheid. Placing this
star in the PâL diagram provides an independent test of existing period-luminosity relations. We show
that the secondary star has a significant impact on the integrated magnitude, particularly at visible
wavelengths. Binarity in future high precision calibrations of the PâL relations is not negligible,
at least in the short-period regime. Subtracting the companion flux leaves V1334 Cyg in marginal
agreement with existing photometric-based PâL relations, indicating either an overall calibration bias
or a significant intrinsic dispersion at a few percent level. Our work also enabled us to determine the
dynamical masses of both components, M1 = 4.288±0.133 M (Cepheid) and M2 = 4.040±0.048 M
(companion), providing the most accurate masses for a Galactic binary Cepheid systemThis research is based on observations made with
SOPHIE spectrograph on the 1.93-m telescope at Ob-
A geometrical 1 % distance to a short-period binary Cepheid 11
servatoire de Haute-Provence (CNRS/AMU), France
(ProgID: 13A.PNPS10, 13B.PNPS003, 14A.PNPS010,
15A.PNPS010, 16B.PNPS.KERV). This research is
based on observations made with the Mercator Telescope,
operated on the island of La Palma by the Flemish
Community, at the Spanish Observatorio del Roque
de los Muchachos of the Instituto de Astrofsica de Canarias.
Hermes is supported by the Fund for Scientific
Research of Flanders (FWO), Belgium; the Research
Council of K.U.Leuven, Belgium; the Fonds National
de la Recherche Scientifique (F.R.S.- FNRS), Belgium;
the Royal Observatory of Belgium; the Observatoire de
Genve, Switzerland; and the Thšuringer Landessternwarte,
Tautenburg, Germany. This work is also based
on observations with the NASA/ESA Hubble Space
Telescope obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities
for Research in Astronomy, Inc., under NASA
contract NAS5-26555 (ProgID 13454). We acknowledge
the support of the French Agence Nationale de
la Recherche (ANR-15-CE31-0012-01, project UnlockCepheids).
WG and GP gratefully acknowledge financial
support from the BASAL Centro de Astrofisica
y Tecnologias Afines (CATA, AFB-170002). WG also
acknowledges financial support from the Millenium Institute
of Astrophysics (MAS) of the Iniciativa Cientifica
Milenio del Ministerio de Economia, Fomento y
Turismo de Chile (project IC120009). We acknowledge
financial support from the Programme National
de Physique Stellaire (PNPS) of CNRS/INSU, France.
Support from the Polish National Science Centre grants
MAESTRO UMO-2017/26/A/ST9/00446 and from the
IdP II 2015 0002 64 grant of the Polish Ministry of
Science and Higher Education is also acknowledged.
The research leading to these results has received funding
from the European Research Council (ERC) under
the European Unionâs Horizon 2020 research and innovation
programme (grant agreement No. 695099 and
639889). NRE acknowledge support from the Chandra
X-ray Center NASA (contract NAS8-03060) and
the HST grants GO-13454.001-A and GO-14194.002.
This work is based upon observations obtained with
the Georgia State University Center for High Angular
Resolution Astronomy Array at Mount Wilson Observatory.
The CHARA Array is supported by the National
Science Foundation under Grants No. AST-1211929,
1411654, and 1636624. Institutional support has been
provided from the GSU College of Arts and Sciences
and the GSU Office of the Vice President for Research
and Economic Development. BP acknowledges financial
support from the Polish National Science Center grant
SONATA 2014/15/D/ST9/02248
Affective stimulus properties influence size perception and the Ebbinghaus illusion
In the New Look literature of the 1950s, it has been suggested that size judgments are dependent on the affective content of stimuli. This suggestion, however, has been âdiscreditedâ due to contradictory findings and methodological problems. In the present study, we revisited this forgotten issue in two experiments. The first experiment investigated the influence of affective content on size perception by examining judgments of the size of target circles with and without affectively loaded (i.e., positive, neutral, and negative) pictures. Circles with a picture were estimated to be smaller than circles without a picture, and circles with a negative picture were estimated to be larger than circles with a positive or a neutral picture confirming the suggestion from the 1950s that size perception is influenced by affective content, an effect notably confined to negatively loaded stimuli. In a second experiment, we examined whether affective content influenced the Ebbinghaus illusion. Participants judged the size of a target circle whereby target and flanker circles differed in affective loading. The results replicated the first experiment. Additionally, the Ebbinghaus illusion was shown to be weakest for a negatively loaded target with positively loaded and blank flankers. A plausible explanation for both sets of experimental findings is that negatively loaded stimuli are more attention demanding than positively loaded or neutral stimuli
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