43 research outputs found
Quail Methodology: Where are We and Where Do We Need to Be?
I review and evaluate methods used for population estimation, determination of survival, radio-tagging, habitat analysis and evaluation, and study design and analysis. I conclude that rigorously designed call-count surveys are likely to provide the best information on quail population trends across time and space. More intensive techniques such as line transects and mark-recapture may be appropriate if the resources are available. Radio-tagging can be a very useful technique; however, in many cases, triangulation error and effects of equipment on the birds may render results suspect. Therefore, caution is urged when using radio-tagging. Approaches to habitat analysis and evaluation are described. I discuss the importance of replication in study design and the use of appropriate and rigorous statistics. I suggest we consider statistical power more in the interpretation of results. Generally, we have the techniques available to meet our needs, but implementation has been less than ideal in many cases. Finally, the dichotomy between researchers and managers needs to be bridged. Better communication of needs by managers and cooperation by researchers should lead to positive results concerning our quail resources
First-year Experience Course: Problem Solving, Inquiry, and Integration
In an effort to address academic deficiencies outlined in recent studies, Virginia Techâs College of Natural Resources and Environment redesigned its first-year experience class to fit their activities into three components of activities: problem solving, inquiry, and integrative learning. The problem solving component required students to define a problem, identify problem-solving strategies, and propose solutions and hypotheses. The inquiry component of the first-year experience included selecting a research topic, learning how to access information about the topic, learning how to evaluate existing information about the topic, and deciding which information to use to achieve desired results about the topic. The final component of the program, integration of learning, connected different programs of study with in-class learning and outside experience. This component also stressed exploring the relationship between studentâs self and their learning experiences. To evaluate these three categories, the Motivated Strategies for Learning Questionnaire and the Information Literacy Test surveys were administered to the students at the beginning of the semester and the end of the semester in order to evaluate student growth in each category, as well as studentsâ own self-awareness. Quantitative analysis of these two surveys illustrates the effectiveness of the assignments associated with each component. Knowledge gained from the redevelopment of the class, quantitative analysis of the surveys, and plans for additional amendments to the class will be shared during conference proceedings
Sustainability Beliefs of First-year Students in Natural Resources
A crux of the environmental problem is change resistance and few college students possess the critical analysis and persuasive communication skills needed to engage in this dialogue. Furthermore, there is little appreciation among college students for the diversity of beliefs regarding sustainability issues. We surveyed students enrolled in a First-Year Experience class in Virginia Techâs College of Natural Resources and Environment. We used the Dunlap and Van Liere New Environmental Paradigm (NEP) measurement scale to assess the individual student orientations toward nature and the environment. The students enrolled in this class had enrolled voluntarily based on their interest in the study of the environment or natural resources. Therefore, it was no surprise that the score reflected a belief orientation towards sustainability. Survey results allowed these first-year students to discover the range of opinion among members of a relatively homogeneous sample. The survey provided insights regarding the human-centered or eco-centered orientation of their student peers. We used these findings to encourage revision of a draft problem-solving essay. We plan further use of the NEP measurement scale in our curriculum and encourage its adoptions by instructors involved in pedagogy of sustainable thinking
Detection of the lithium depletion boundary in the young open cluster IC 4665
The so-called lithium depletion boundary (LDB) provides a secure and
independent tool for deriving the ages of young open clusters.In this context,
our goal is to determine membership for a sample of 147 photometrically
selected candidates of the young open cluster IC 4665 and to use confirmed
members to establish an age based on the LDB. Employing the FLAMES multi-object
spectrograph on VLT/UT2, we have obtained intermediate-resolution spectra of
the cluster candidates. The spectra were used to measure radial velocities and
to infer the presence of the Li I 670.8 nm doublet and Halpha emission. We have
identified 39 bona fide cluster members based on radial velocity, Halpha
emission, and Li absorption. The mean radial velocity of IC 4665 is found to be
vrad=-15.95 +/- 1.13 km/s. Confirmed cluster members display a sharp transition
in magnitude between stars with and without lithium, both in the Im vs. Im-z
and in the Ks vs. Im-Ks diagrams.From this boundary, we deduce a cluster age of
27.7^(+4.2)_(-3.5) +/- 1.1 +/- 2 Myr. IC 4665 is the fifth cluster for which an
LDB age has been determined, and it is the youngest cluster among these five.
Thus, the LDB is established from relatively bright stars still in the
contracting pre-main sequence phase. The mass of the boundary is M*=0.24 +/-
0.04 Msun. The LDB age agrees well with the ages derived from isochrone fitting
of both low and high mass, turn-off stars, a result similar to what is found in
the slightly older NGC 2547.Comment: 13 pages, A&A in pres
Formation and Evolution of Planetary Systems: Placing Our Solar System in Context with Spitzer
We summarize the progress to date of our Legacy Science Program entitled "The
Formation and Evolution of Planetary Systems" (FEPS) based on observations
obtained with the Spitzer Space Telescope during its first year of operation.
In addition to results obtained from our ground-based preparatory program and
our early validation program, we describe new results from a survey for
near-infrared excess emission from the youngest stars in our sample as well as
a search for cold debris disks around sun-like stars. We discuss the
implications of our findings with respect to current understanding of the
formation and evolution of our own solar system.Comment: 8 postscript pages including 3 figures. To appear in "Spitzer New
Views of the Cosmos" ASP Conference Series, eds. L. Armus et al. FEPS website
at http://feps.as.arizona.ed
Scanning micro-X-ray fluorescence elemental mapping : a new tool for the study of laminated sediment records
Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 9 (2008): Q02016, doi:10.1029/2007GC001800.The utility of elemental mapping by scanning X-ray fluorescence (XRF) in the study of annual laminated sedimentary records was investigated on eight annually laminated sediment types. The examples were chosen to illustrate the potential of this approach in environments dominated by terrigenous, biological and chemical deposition. Individual laminae were identifiable in elemental maps of all sediment types and were enhanced through the use of data reduction techniques (e.g., principal components transformation). Laminae were least apparent in clastic dominated systems with no seasonal changes in sediment sources. In biologically dominated systems, element maps provided insights into the composition of the varve subcomponents, related to alternating terrigenous and biologically dominated seasonal periods of deposition. Chemically precipitated structures were more prevalent than expected from visual investigations alone and may provide an underutilized paleoenvironmental signature of changing limnological conditions. Elemental mapping offers a valuable tool for the study of laminated records that complements existing techniques (e.g., SEM, digital image analysis).Funding was provided through NSF Earth System History
grants and an NSF Instrumentation grant awarded to J.T.O
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
We describe the design and performance of the near-infrared (1.51--1.70
micron), fiber-fed, multi-object (300 fibers), high resolution (R =
lambda/delta lambda ~ 22,500) spectrograph built for the Apache Point
Observatory Galactic Evolution Experiment (APOGEE). APOGEE is a survey of ~
10^5 red giant stars that systematically sampled all Milky Way populations
(bulge, disk, and halo) to study the Galaxy's chemical and kinematical history.
It was part of the Sloan Digital Sky Survey III (SDSS-III) from 2011 -- 2014
using the 2.5 m Sloan Foundation Telescope at Apache Point Observatory, New
Mexico. The APOGEE-2 survey is now using the spectrograph as part of SDSS-IV,
as well as a second spectrograph, a close copy of the first, operating at the
2.5 m du Pont Telescope at Las Campanas Observatory in Chile. Although several
fiber-fed, multi-object, high resolution spectrographs have been built for
visual wavelength spectroscopy, the APOGEE spectrograph is one of the first
such instruments built for observations in the near-infrared. The instrument's
successful development was enabled by several key innovations, including a
"gang connector" to allow simultaneous connections of 300 fibers; hermetically
sealed feedthroughs to allow fibers to pass through the cryostat wall
continuously; the first cryogenically deployed mosaic volume phase holographic
grating; and a large refractive camera that includes mono-crystalline silicon
and fused silica elements with diameters as large as ~ 400 mm. This paper
contains a comprehensive description of all aspects of the instrument including
the fiber system, optics and opto-mechanics, detector arrays, mechanics and
cryogenics, instrument control, calibration system, optical performance and
stability, lessons learned, and design changes for the second instrument.Comment: 81 pages, 67 figures, PASP, accepte
The impact of tides on the capillary transition zone
The capillary transition zone, also known as the capillary fringe, is a zone where water saturations decrease with height above the water table/oilâwater contact as a result of capillary action. In some oil reservoirs, this zone may contain a significant proportion of the oil in place. In groundwater assessments, the capillary fringe can profoundly affect contaminant transport. In this study, we investigated the influence of a tidally induced, semi-diurnal, change in water table depth on the water saturation distribution in the capillary fringe/transition zone. The investigation used a mixture of laboratory experiments, in which the change in saturation with depth was monitored over a period of 90 days, and numerical simulation. We show that tidal changes in water table depth can significantly alter the vertical water saturation profile from what would be predicted using capillaryâgravity equilibrium and the drainage or imbibition capillary pressure curves
Rotation and activity in the solar-metallicity open cluster NGC2516
We report new measures of radial velocities and rotation rates (v sin i) for
51 F and early-G stars in the open cluster NGC2516, and combine these with
previously published data. From high signal-to-noise spectra of two stars, we
show that NGC2516 has a relative iron abundance with respect to the Pleiades of
delta([Fe/H])= +0.04 +/- 0.07 at the canonical reddening of E(B - V) = 0.12, in
contrast to previous photometric studies that placed the cluster 0.2 to 0.4 dex
below solar. We construct a color-magnitude diagram based on radial velocity
members, and explore the sensitivity of photometric determinations of the
metallicity and distance to assumed values of the reddening. For a metal
abundance near solar, the Hipparcos distance to NGC2516 is probably
underestimated. Finally, we show that the distribution of rotation rates and
X-ray emission does not differ greatly from that of the Pleiades, when
allowance is made for the somewhat older age of NGC2516.Comment: Accepted for publication in the Astrophysical Journal. 35 pages
including 7 figure
Spitzer Observations of G Dwarfs in the Pleiades: Circumstellar Debris Disks at 100 Myr Age
Fluxes and upper limits in the wavelength range from 3.6 to 70 microns from
the Spitzer Space Telescope are provided for twenty solar-mass Pleiades
members. One of these stars shows a probable mid-IR excess and two others have
possible excesses, presumably due to circumstellar debris disks. For the star
with the largest, most secure excess flux at MIPS wavelengths, HII1101, we
derive Log(L[dust]/L[Sun]) ~ -3.8 and an estimated debris disk mass of 4.2 x
10^-5 M(Earth) for an assumed uniform dust grain size of 10 microns If the
stars with detected excesses are interpreted as stars with relatively recent,
large collision events producing a transient excess of small dust particles,
the frequency of such disk transients is about ~ 10 % for our ~ 100 Myr,
Pleiades G dwarf sample. For the stars without detected 24-70 micron excesses,
the upper limits to their fluxes correspond to approximate 3 sigma upper limits
to their disk masses of 6 x 10^-6 M(Earth) using the MIPS 24 micron upper
limit, or 2 x 10^-4 M(Earth) using the MIPS 70 micron limit. These upper limit
disk masses (for "warm" and "cold" dust, respectively) are roughly consistent,
but somewhat lower than, predictions of a heuristic model for the evolution of
an "average" solar-mass star's debris disk based on extrapolation backwards in
time from current properties of the Sun's Kuiper belt.Comment: 32 postscript pages including 8 figues and 3 tables. To appear in the
Astronomical Journa