138 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
The Formation and Evolution of Planetary Systems: Description of the Spitzer Legacy Science Database
We present the science database produced by the Formation and Evolution of
Planetary Systems (FEPS) Spitzer Legacy program. Data reduction and validation
procedures for the IRAC, MIPS, and IRS instruments are described in detail. We
also derive stellar properties for the FEPS sample from available broad-band
photometry and spectral types, and present an algorithm to normalize Kurucz
synthetic spectra to optical and near-infrared photometry. The final FEPS data
products include IRAC and MIPS photometry for each star in the FEPS sample and
calibrated IRS spectra.Comment: 64 pages, 12 figures, 5 tables; accepted for publication in ApJ
First-year Experience Course: Problem Solving, Inquiry, and Integration
In an effort to address academic deficiencies outlined in recent studies, Virginia Tech’s 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 student’s 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 students’ 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 Tech’s 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
Exact Solution of a Drop-push Model for Percolation
Motivated by a computer science algorithm known as `linear probing with
hashing' we study a new type of percolation model whose basic features include
a sequential `dropping' of particles on a substrate followed by their transport
via a `pushing' mechanism. Our exact solution in one dimension shows that,
unlike the ordinary random percolation model, the drop-push model has
nontrivial spatial correlations generated by the dynamics itself. The critical
exponents in the drop-push model are also different from that of the ordinary
percolation. The relevance of our results to computer science is pointed out.Comment: 4 pages revtex, 2 eps figure
The role of mentorship in protege performance
The role of mentorship on protege performance is a matter of importance to
academic, business, and governmental organizations. While the benefits of
mentorship for proteges, mentors and their organizations are apparent, the
extent to which proteges mimic their mentors' career choices and acquire their
mentorship skills is unclear. Here, we investigate one aspect of mentor
emulation by studying mentorship fecundity---the number of proteges a mentor
trains---with data from the Mathematics Genealogy Project, which tracks the
mentorship record of thousands of mathematicians over several centuries. We
demonstrate that fecundity among academic mathematicians is correlated with
other measures of academic success. We also find that the average fecundity of
mentors remains stable over 60 years of recorded mentorship. We further uncover
three significant correlations in mentorship fecundity. First, mentors with
small mentorship fecundity train proteges that go on to have a 37% larger than
expected mentorship fecundity. Second, in the first third of their career,
mentors with large fecundity train proteges that go on to have a 29% larger
than expected fecundity. Finally, in the last third of their career, mentors
with large fecundity train proteges that go on to have a 31% smaller than
expected fecundity.Comment: 23 pages double-spaced, 4 figure
Formation and Evolution of Planetary Systems (FEPS): Properties of Debris Dust around Solar-type Stars
We present Spitzer photometric (IRAC and MIPS) and spectroscopic (IRS low
resolution) observations for 314 stars in the Formation and Evolution of
Planetary Systems (FEPS) Legacy program. These data are used to investigate the
properties and evolution of circumstellar dust around solar-type stars spanning
ages from approximately 3 Myr to 3 Gyr. We identify 46 sources that exhibit
excess infrared emission above the stellar photosphere at 24um, and 21 sources
with excesses at 70um. Five sources with an infrared excess have
characteristics of optically thick primordial disks, while the remaining
sources have properties akin to debris systems. The fraction of systems
exhibiting a 24um excess greater than 10.2% above the photosphere is 15% for
ages < 300 Myr and declines to 2.7% for older ages. The upper envelope to the
70um fractional luminosity appears to decline over a similar age range. The
characteristic temperature of the debris inferred from the IRS spectra range
between 60 and 180 K, with evidence for the presence of cooler dust to account
for the strength of the 70um excess emission. No strong correlation is found
between dust temperature and stellar age. Comparison of the observational data
with disk models containing a power-law distribution of silicate grains suggest
that the typical inner disk radius is > 10 AU. Although the interpretation is
not unique, the lack of excess emission shortwards of 16um and the relatively
flat distribution of the 24um excess for ages <300~Myr is consistent with
steady-state collisional models.Comment: 85 pages, 18 figures, 4 tables; accepted for publication in ApJ
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
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