8,686 research outputs found
Teacher Tricks A.K.A. Parent Tools: Workshops to Promote Healthy Family Literacy
Four workshops, supported by research on parent involvement, were developed to help promote family literacy. Each workshop incorporates both parents and students as they are encouraged to read preassigned books together. In addition, each family was given tasks to complete as they read their books. Workshops incorporating helpful tips and suggestions were provided to the families so they could better assist their children with their reading needs
Policy-driven planning in coalitions - A case study
(c)IFAAMASPeer reviewedPostprin
Molecular Gas Properties of the Giant Molecular Cloud Complexes in the Arms and Inter-arms of the Spiral Galaxy NGC 6946
Combining observations of multiple CO lines with radiative transfer modeling
is a very powerful tool to investigate the physical properties of the molecular
gas in galaxies. Using new observations as well as literature data, we provide
the most complete CO ladders ever generated for eight star-forming regions in
the spiral arms and inter-arms of the spiral galaxy NGC 6946, with observations
of the CO(1-0), CO(2-1), CO(3-2), CO(4-3), CO(6-5), 13CO(1-0) and 13CO(2-1)
transitions. For each region, we use the large velocity gradient assumption to
derive beam-averaged molecular gas physical properties, namely the gas kinetic
temperature (T_K), H2 number volume density n(H2) and CO number column density
N(CO). Two complementary approaches are used to compare the observations with
the model predictions: chi-square minimisation and likelihood. The physical
conditions derived vary greatly from one region to the next: T_K=10-250 K,
n(H2)=10^2.3-10^7.0 cm^-3 and N(CO)=10^15.0-10^19.3 cm^-2. The spectral line
energy distribution (SLED) of some of these extranuclear regions indicates a
star-formation activity that is more intense than that at the centre of our own
Milky Way. The molecular gas in regions with a large SLED turnover transition
(J_max>4) is hot but tenuous with a high CO column density, while that in
regions with a low SLED turnover transition (J_max<=4) is cold but dense with a
low CO column density. We finally discuss and find some correlations between
the physical properties of the molecular gas in each region and the presence of
young stellar population indicators (supernova remnants, HII regions, HI holes,
etc.)Comment: 23 pages, 11 figures, MNRAS, Accepte
The Economics of Exporting North Dakota Beef to Asian Pacific Markets
International Relations/Trade,
A black-hole mass measurement from molecular gas kinematics in NGC4526
The masses of the supermassive black-holes found in galaxy bulges are
correlated with a multitude of galaxy properties, leading to suggestions that
galaxies and black-holes may evolve together. The number of reliably measured
black-hole masses is small, and the number of methods for measuring them is
limited, holding back attempts to understand this co-evolution. Directly
measuring black-hole masses is currently possible with stellar kinematics (in
early-type galaxies), ionised-gas kinematics (in some spiral and early-type
galaxies) and in rare objects which have central maser emission. Here we report
that by modelling the effect of a black-hole on the kinematics of molecular gas
it is possible to fit interferometric observations of CO emission and thereby
accurately estimate black hole masses. We study the dynamics of the gas in the
early-type galaxy NGC4526, and obtain a best fit which requires the presence of
a central dark-object of 4.5(+4.2-3.0)x10^8 Msun (3 sigma confidence limit).
With next generation mm-interferometers (e.g. ALMA) these observations could be
reproduced in galaxies out to 75 megaparsecs in less the 5 hours of observing
time. The use of molecular gas as a kinematic tracer should thus allow one to
estimate black-hole masses in hundreds of galaxies in the local universe, many
more than accessible with current techniques.Comment: To appear in Nature online on 30/01/2013. 3 Pages, 2 Figures (plus
two pages of supplementary information
ISM chemistry in metal rich environments: molecular tracers of metallicity
In this paper we use observations of molecular tracers in metal rich and
alpha-enhanced galaxies to study the effect of abundance changes on molecular
chemistry. We selected a sample of metal rich spiral and star bursting objects
from the literature, and present here new data for a sample of early-type
galaxies (ETGs). We conducted the first survey of CS and methanol emission in
ETGs, detecting 7 objects in CS, and 5 in methanol emission. We find evidence
to support the hypothesis that CS is a better tracer of dense star-forming gas
than HCN. We suggest that the methanol emission in these sources is driven by
dust mantle destruction due to ionisation from high mass star formation, but
cannot rule out shocks dominating in some sources. The derived source averaged
CS/methanol column densities and rotation temperatures are similar to those
found in normal spiral and starburst galaxies, suggesting dense clouds are
little affected by the differences between galaxy types. Finally we used the
total column density ratios for our galaxy samples to show for the first time
that some molecular tracers do seem to show systematic variations that appear
to correlate with metallicity, and that these variations roughly match those
predicted by chemical models. Using this fact, the chemical models of Bayet et
al. (2012b), and assumptions about the optical depth we are able to roughly
predict the metallicity of our spiral and ETG sample, with a scatter of ~0.3
dex. We provide the community with linear approximations to the relationship
between the HCN and CS column density ratio and metallicity. Further study will
clearly be required to determine if this, or any, molecular tracer can be used
to robustly determine gas-phase metallically, but that a relationship exists at
all suggests that in the future it may be possible to calibrate a metallicity
indicator for the molecular interstellar medium (abridged).Comment: 14 pages, 9 figures. MNRAS, accepte
On the depletion and accretion time-scales of cold gas in local early-type galaxies
We consider what can be learnt about the processes of gas accretion and depletion from the kinematic misalignment between the cold/warm gas and stars in local early-type galaxies. Using simple analytic arguments and a toy model of the processes involved, we show that the lack of objects with counter-rotating gas reservoirs strongly constrains the relaxation, depletion and accretion time-scales of gas in early-type galaxies. Standard values of the accretion rate, star-formation efficiency and relaxation rate are not simultaneously consistent with the observed distribution of kinematic misalignments. To reproduce that distribution, both fast gas depletion (tdep ≲ 108 yr; e.g. more efficient star formation) and fast gas destruction (e.g. by active galactic nucleus feedback) can be invoked, but both also require a high rate of gas-rich mergers (>1 Gyr−1). Alternatively, the relaxation of misaligned material could happen over very long time-scales (≃100 dynamical times or ≈1–5 Gyr). We explore the various physical processes that could lead to fast gas depletion and/or slow gas relaxation, and discuss the prospects of using kinematic misalignments to probe gas-rich accretion processes in the era of large integral-field spectroscopic surveys
VIDEO SURVEILLANCE OF NESTING WHOOPING CRANES
The primary objective of the whooping crane (Grus americana) recovery plan is to establish and maintain 3 selfsustaining wild populations, 1 being a non-migratory Florida population. From 1993 to 2005, we released 289 captive cranes in central Florida, with 31 surviving as of 1 June 2008. From 1995 to 2008 we monitored 68 nests of the Florida population; from those, only 32 chicks hatched and 9 fledged. It often was not apparent why nests failed, and it was not practical to conduct labor-intensive observations at nests; therefore, we collected behavioral data using 12-volt VHS video surveillance cameras at 13 nests from 2000 to 2008. We positioned cameras and time-lapse video recorders 200-500 m from each nest. We programmed 1-3 days/tape of recording to occur from 1 hour before sunrise to 1 hour after sunset. Seven of 13 nests were successful in hatching chicks, while the remainder failed during the incubation period. Relevant events recorded on the videotapes included: incubation durations, frequency of adults switching off during incubation, frequency of standing and egg turning, duration eggs were not incubated while adults were away, and possible causes of nest failure. Summary statistics relating to these behaviors and also to their possible implications regarding nest survival will be discussed. Video surveillance was a valuable tool for the efficient gathering of behavioral data at whooping crane nests
A Chandra Study of the Effects of a Major Merger on the Structure of Abell 2319
We present an analysis of a Chandra observation of the massive, nearby galaxy
cluster Abell 2319. A sharp surface brightness discontinuity--suggested by
previous, lower angular resolution X-ray imaging--is clearly visible in the
ACIS image. This roughly 300kpc feature suggests that a major merger is taking
place with a significant velocity component perpendicular to the line of sight.
The cluster emission-weighted mean temperature is 11.8+/-0.6kev, somewhat
higher than previous temperature measurements. The Chandra temperature map of
A2319 reveals substructure resembling that anticipated based on hydrodynamic
simulations of cluster mergers. The merger feature shows a pressure change
across the surface brightness discontinuity by a factor of <=2.5. The higher
density side of the front has a lower temperature, suggesting the presence of a
cold front similar to those in many other merging clusters. The velocity of the
front is roughly sonic.
We compare bulk properties of the ICM and galaxies in A2319 to the same
properties in a large sample of clusters as a way of gauging the effects of the
major merger. Interestingly, by comparing A2319 to a sample of 44 clusters
studied with the ROSAT PSPC we find that the X-ray luminosity, isophotal size,
and ICM mass are consistent with the expected values for a cluster of its
temperature; in addition, the K-band galaxy light is consistent with the
light--temperature scaling relation derived from a sample of about 100 clusters
studied with 2MASS. Together, these results indicate either that the merger in
A2319 has not been effective at altering the bulk properties of the cluster, or
that there are large but correlated displacements in these quantities.Comment: 11 pages, 8 figures, ApJ Submitte
Vented Tank Resupply Experiment--Flight Test Results
This paper reports the results of the Vented Tank Resupply Experiment (VTRE) which was flown as a payload on STS 77. VTRE looks at the ability of vane Propellant Management Devices (PMD) to separate liquid and gas in low gravity. VTRE used two clear 0.8 cubic foot tanks one spherical and one with a short barrel section and transferred Refrigerant 113 between them as well as venting it to space. Tests included retention of liquid during transfer, liquid free venting, and recovery of liquid into the PMD after thruster firing. Liquid was retained successfully at the highest flow rate tested (2.73 gpm). Liquid free vents were achieved for both tanks, although at a higher flow rate (0.1591 cfm) for the spherical tank than the other (0.0400 cfm). Recovery from a thruster firing which moved the liquid to the opposite end of the tank from the PMD was achieved in 30 seconds
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