820 research outputs found
The discovery and preliminary thermoluminescence dating of two Aboriginal cave shelters in the Selwyn Ranges, Queensland
Two apparently undisturbed cave shelters near Selwyn in the Selwyn Ranges in Queensland were discovered by one of us (G.G.) during 1977. The first of these, referred to as Site 1 is located at Lat. 21°23'; Long. 140°32'. The second referred to as Site 2, is located approximately lO km SE of the first. Rock paintings were present in both shelters but were not recorded in detail
Star Formation in a Stellar Mass Selected Sample of Galaxies to z=3 from the GOODS NICMOS Survey (GNS)
We present a study of the star-forming properties of a stellar mass-selected
sample of galaxies in the GOODS NICMOS Survey (GNS), based on deep Hubble Space
Telescope imaging of the GOODS North and South fields. Using a stellar mass
selected sample, combined with HST/ACS and Spitzer data to measure both UV and
infrared derived star formation rates (SFR), we investigate the star forming
properties of a complete sample of ~1300 galaxies down to log M*=9.5 at
redshifts 1.5<z<3. Eight percent of the sample is made up of massive galaxies
with M*>10^11 Msun. We derive optical colours, dust extinctions, and
ultraviolet and infrared SFR to determine how the star formation rate changes
as a function of both stellar mass and time. Our results show that SFR
increases at higher stellar mass such that massive galaxies nearly double their
stellar mass from star formation alone over the redshift range studied, but the
average value of SFR for a given stellar mass remains constant over this 2 Gyr
period. Furthermore, we find no strong evolution in the SFR for our sample as a
function of mass over our redshift range of interest, in particular we do not
find a decline in the SFR among massive galaxies, as is seen at z < 1. The most
massive galaxies in our sample (log M*>11) have high average SFRs with values,
SFR(UV,corr) = 103+/-75 Msun/yr, yet exhibit red rest-frame (U-B) colours at
all redshifts. We conclude that the majority of these red high-redshift massive
galaxies are red due to dust extinction. We find that A(2800) increases with
stellar mass, and show that between 45% and 85% of massive galaxies harbour
dusty star formation. These results show that even just a few Gyr after the
first galaxies appear, there are strong relations between the global physical
properties of galaxies, driven by stellar mass or another underlying feature of
galaxies strongly related to the stellar mass.Comment: 18 pages, 10 figures, accepted for publication in MNRA
How neutral is the intergalactic medium surrounding the redshift z=7.085 quasar ULAS J1120+0641?
The quasar ULAS J1120+0641 at redshift z=7.085 has a highly ionised near zone
which is smaller than those around quasars of similar luminosity at z~6. The
spectrum also exhibits evidence for a damping wing extending redward of the
systemic Lya redshift. We use radiative transfer simulations in a cosmological
context to investigate the implications for the ionisation state of the
inhomogeneous IGM surrounding this quasar. Our simulations show that the
transmission profile is consistent with an IGM in the vicinity of the quasar
with a volume averaged HI fraction of f_HI>0.1 and that ULAS J1120+0641 has
been bright for 10^6--10^7 yr. The observed spectrum is also consistent with
smaller IGM neutral fractions, f_HI ~ 10^-3--10-4, if a damped Lya system in an
otherwise highly ionised IGM lies within 5 proper Mpc of the quasar. This is,
however, predicted to occur in only ~5 per cent of our simulated sight-lines
for a bright phase of 10^6--10^7 yr. Unless ULAS J1120+0641 grows during a
previous optically obscured phase, the low age inferred for the quasar adds to
the theoretical challenge of forming a 2x10^9 M_sol black hole at this high
redshift.Comment: 5 pages, 4 figures, accepted to MNRAS letter
Preparing Engineering Duty Officers (EDOs) for Command of Major Acquisition Shore Commands and Major Acquisition Programs
NPS NRP Technical ReportThe U.S. Navy's capabilities regarding the entire sequence of ships and shipboard systems acquisition (research, development, testing, production, deployment, and operations/maintenance of ships and shipboard systems) needs continuous improvement to counter advancing threats. Engineering Duty Officers (EDOs) have long been associated with these capabilities in both technical and leadership positions. Over the years, the range and complexity of these professional areas have increased, and some of the developmental leadership opportunities have become diluted. This study will conduct a focused analysis of the current fundamental leadership and professional development for EDOs in comparison with those of other Navy communities and Department of Defense (DoD) agencies and with private best practices. It will then focus on determining the leadership experiences required to prepare EDOs to successfully take command and lead the Navy's large, complex civilian organizations such as shipyards or regional maintenance centers. Based on findings, we will make recommendations for improving the EDO community talent management practices to successfully prepare EDOs for command and leadership of major shore acquisition commands. The study's findings will impact the Navy's capabilities regarding the research, development, testing, production, deployment, and operations and maintenance of ships and shipboard systems.N1 - Manpower, Personnel, Training & EducationThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.
Preparing Engineering Duty Officers (EDOs) for Command of Major Acquisition Shore Commands and Major Acquisition Programs
NPS NRP Executive SummaryThe U.S. Navy's capabilities regarding the entire sequence of ships and shipboard systems acquisition (research, development, testing, production, deployment, and operations/maintenance of ships and shipboard systems) needs continuous improvement to counter advancing threats. Engineering Duty Officers (EDOs) have long been associated with these capabilities in both technical and leadership positions. Over the years, the range and complexity of these professional areas have increased, and some of the developmental leadership opportunities have become diluted. This study will conduct a focused analysis of the current fundamental leadership and professional development for EDOs in comparison with those of other Navy communities and Department of Defense (DoD) agencies and with private best practices. It will then focus on determining the leadership experiences required to prepare EDOs to successfully take command and lead the Navy's large, complex civilian organizations such as shipyards or regional maintenance centers. Based on findings, we will make recommendations for improving the EDO community talent management practices to successfully prepare EDOs for command and leadership of major shore acquisition commands. The study's findings will impact the Navy's capabilities regarding the research, development, testing, production, deployment, and operations and maintenance of ships and shipboard systems.N1 - Manpower, Personnel, Training & EducationThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.
Galactic conformity and central/satellite quenching, from the satellite profiles of M* galaxies at 0.4 < z < 1.9 in the UKIDSS UDS
We explore the redshift evolution of a curious correlation between the star formation properties of central galaxies and their satellites (‘galactic conformity') at intermediate to high redshift (0.4 9.7, around central galaxies at the characteristic Schechter function mass, M ∼ M*. We fit the radial profiles of satellite number densities with simple power laws, finding slopes in the range −1.1 to −1.4 for mass-selected satellites, and −1.3 to −1.6 for passive satellites. We confirm the tendency for passive satellites to be preferentially located around passive central galaxies at 3σ significance and show that it exists to at least z ∼ 2. Meanwhile, the quenched fraction of satellites around star-forming galaxies is consistent with field galaxies of equal stellar masses. We find no convincing evidence for a redshift-dependent evolution of these trends. One simple interpretation of these results is that only passive central galaxies occupy an environment that is capable of independently shutting off star formation in satellite galaxies. By examining the satellites of higher stellar mass star-forming galaxies (log(M*/M⊙) > 11), we conclude that the origin of galactic conformity is unlikely to be exclusively due to the host dark matter halo mass. A halo-mass-independent correlation could be established by either formation bias or a more physical connection between central and satellite star formation histories. For the latter, we argue that a star formation (or active galactic nucleus) related outburst event from the central galaxy could establish a hot halo environment which is then capable of quenching both central and satellite galaxie
A Maximum Likelihood Analysis of the Low CMB Multipoles from WMAP
The amplitudes of the quadrupole and octopole measured from the Wilkinson
Microwave Anisotropy Probe (WMAP) appear to be lower than expected according to
the concordance Lambda CDM cosmology. However, the pseudo-Cl estimator used by
the WMAP team is non-optimal. In this paper, we discuss the effects of Galactic
cuts on pseudo-Cl and quadratic maximum likelihood estimators. An application
of a quadratic maximum likelihood estimator to Galaxy subtracted maps produced
by the WMAP team and Tegmark, de Oliveira-Costa and Hamilton (2003) shows that
the amplitudes of the low multipoles are stable to different Galactic cuts. In
particular, the quadrupole and octopole amplitudes are found to lie in the
ranges 176 - 250 (micro K)**2 794 - 1183 (micro K)**2 (and more likely to be at
the upper ends of these ranges) rather than the values of 123 (micro K)**2 and
611 (micro K)**2 found by the WMAP team. These results indicate that the
discrepancy with the concordance Lambda CDM model at low multipoles is not
particularly significant and is in the region of a few percent. This conclusion
is consistent with an analysis of the low amplitude of the angular correlation
function computed from quadratic maximum likelihood power spectrum estimates.Comment: MNRAS (2004) 348 885. Resubmission matches published versio
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