8,265 research outputs found
Estimating Bobwhite Population Size by Direct Counts and the Lincoln Index
Thirteen paired estimates of bobwhite (Colinus virginianus) populations were obtained using the Lincoln Index and a Walk Census on two study areas in Florida and one in Tennessee, Population densities ranged from 1,0 to 7,6 birds/ha as estimated by the Lincoln Index , Unadjusted estimates obtained by the Walk Census averaged 51 percent of those obtained by the Lincoln Index, The correlation coefficient (r) for the 13 paired estimates was 0,96, The linear relationship between the Walk Census and Lincoln Index estimates was defined by y = l,65x + 101.6, where y = Lincoln Index estimate and x = Walk Census estimate, The Lincoln Index gave an unbiased estimate of the true population; either adjusting the Walk Census estimates by doubling the count or using the predictive equation generally produced acceptable estimates of the true population
Vanishing Hall Resistance at High Magnetic Field in a Double Layer Two-Dimensional Electron System
At total Landau level filling factor a double layer
two-dimensional electron system with small interlayer separation supports a
collective state possessing spontaneous interlayer phase coherence. This state
exhibits the quantized Hall effect when equal electrical currents flow in
parallel through the two layers. In contrast, if the currents in the two layers
are equal, but oppositely directed, both the longitudinal and Hall resistances
of each layer vanish in the low temperature limit. This finding supports the
prediction that the ground state at is an excitonic superfluid.Comment: 4 pages, 4 figure
Bark-Tissue Thickness of Coastal Western Hemlock in British Columbia
Bark-tissue thicknesses of coastal western hemlock are reported. Variation in these characteristics is considered between sites, trees, and height positions. Total bark thickness did not vary significantly with site, averaging 7.4 mm, 12.2 mm, and 12.6 mm for the top, middle, and butt height positions, respectively. However, the relative contribution of the individual tissues to the total thickness did vary with site. The thickness of all bark characteristics varied with height, being least at the top position, but differing very little between middle and butt positions
A 10-year Study of Bobwhite Quail Movement Patterns
The movement patterns of 676 bobwhite quail (Colinus virginianus) on two study areas on Tall Timbers Research Station in northern Florida were studied during a 10-year period. Eighty-six percent of the quail moved no more than 400 m from their first documented location in a one- to five-year period. Ninety-eight percent moved less than 800 m. Movements greater than 1,000 m occurred but were rare. There were no substantial differences in the annual movements of males and females or immatures and adults; however, the few birds which made longer movements ()800 m) tended to be immature males. The average distance an individual quail moved during a two-week shooting period was greater than the distance moved during the preceding two-week trapping period, but the average difference was only 82 m and therefore insignificant from a practical viewpoint. Movements during shooting averaged 150 m and were not extensive enough to force quail off the study area. Egress and ingress were minimal and approximately balanced. The population was much less mobile than bobwhite populations in other portions of the species\u27 range
VETA-I x ray test analysis
This interim report presents some definitive results from our analysis of the VETA-I x-ray testing data. It also provides a description of the hardware and software used in the conduct of the VETA-I x-ray test program performed at the MSFC x-ray Calibration Facility (XRCF). These test results also serve to supply data and information to include in the TRW final report required by DPD 692, DR XC04. To provide an authoritative compendium of results, we have taken nine papers as published in the SPIE Symposium, 'Grazing Incidence X-ray/EUV Optics for Astronomy and Projection Lithography' and have reproduced them as the content of this report
The focused ion beam as an integrated circuit restructuring tool
One of the capabilities of focused ion beam systems is ion milling. The purpose of this work is to explore this capability as a tool for integrated circuit restructuring. Methods for cutting and joining conductors are needed. Two methods for joining conductors are demonstrated. The first consists of spinning nitrocellulose (a selfādeveloping resist) on the circuit, ion exposing an area, say, 7Ć7 Ī¼m, then milling a smaller via with sloping sidewalls through the first metal layer down to the second, eābeam evaporating metal, and then dissolving the nitrocellulose to achieve liftoff. The resistance of these links between two metal levels varied from 1 to 7 Ī©. The second, simpler method consists of milling a via with vertical sidewalls down to the lower metal layer, then reducing the milling scan to a smaller area in the center of this via, thereby redepositing the metal from the lower layer on the vertical sidewall. The short circuit thus achieved varied from 0.4 to 1.5 Ī© for vias of dimensions 3Ć3 Ī¼m to 1Ć1 Ī¼m, respectively. The time to mill a 1Ć1 Ī¼m via with a 68 keV Ga+ beam, of 220 Pa current is 60 s. In a system optimized for this application, this milling time is expected to be reduced by a factor of at least 100. In addition, cuts have been made in 1āĪ¼māthick Al films covered by 0.65 Ī¼m of SiO2. These cuts have resistances in excess of 20 MĪ©. This method of circuit restructuring can work at dimensions a factor of 10 smaller than laser zapping and requires no special sites to be fabricated
Chandra Observation of Abell 2142: Survival of Dense Subcluster Cores in a Merger
We use Chandra data to map the gas temperature in the central region of the
merging cluster A2142. The cluster is markedly nonisothermal; it appears that
the central cooling flow has been disturbed but not destroyed by a merger. The
X-ray image exhibits two sharp, bow-shaped, shock-like surface brightness edges
or gas density discontinuities. However, temperature and pressure profiles
across these edges indicate that these are not shock fronts. The pressure is
reasonably continuous across these edges, while the entropy jumps in the
opposite sense to that in a shock (i.e. the denser side of the edge has lower
temperature, and hence lower entropy). Most plausibly, these edges delineate
the dense subcluster cores that have survived a merger and ram pressure
stripping by the surrounding shock-heated gas.Comment: Latex, 9 pages, 5 figures (including color), uses emulateapj.sty.
Submitted to Ap
The TWA 3 Young Triple System: Orbits, Disks, Evolution
We have characterized the spectroscopic orbit of the TWA 3A binary and
provide preliminary families of probable solutions for the TWA 3A visual orbit
as well as for the wide TWA 3A--B orbit. TWA 3 is a hierarchical triple located
at 34 pc in the 10 Myr old TW Hya association. The wide component
separation is 1."55; the close pair was first identified as a possible binary
almost 20 years ago. We initially identified the 35-day period orbital solution
using high-resolution infrared spectroscopy which angularly resolved the A and
B components. We then refined the preliminary orbit by combining the infrared
data with a re-analysis of our high-resolution optical spectroscopy. The
orbital period from the combined spectroscopic solution is 35 days, the
eccentricity is 0.63, and the mass ratio is 0.84; although this
high mass ratio would suggest that optical spectroscopy alone should be
sufficient to identify the orbital solution, the presence of the tertiary B
component likely introduced confusion in the blended optical spectra. Using
millimeter imaging from the literature, we also estimate the inclinations of
the stellar orbital planes with respect to the TWA 3A circumbinary disk
inclination and find that all three planes are likely misaligned by at least
30 degrees. The TWA 3A spectroscopic binary components have spectral
types of M4.0 and M4.5; TWA 3B is an M3. We speculate that the system formed as
a triple, is bound, and that its properties were shaped by dynamical
interactions between the inclined orbits and disk.Comment: Accepted to Ap
A Guide to Simple and Informative Binding Assays
The aim of binding assays is to measure interactions between two molecules, such as a protein binding another protein, a small molecule, or a nucleic acid. Hard work is required to prepare reagents, but flaws in the design of many binding experiments limit the information obtained. In particular many experiments fail to measure the affinity of the reactants for each other. This essay describes simple methods to get the most out of valuable reagents in binding experiments
High brightness inductively coupled plasma source for high current focused ion beam applications
A high brightnessplasmaion source has been developed to address focused ion beam(FIB) applications not satisfied by the liquid metal ion source (LMIS) based FIB. The plasmaFIB described here is capable of satisfying applications requiring high mill rates (>100Ī¼mĀ³/s) with non-gallium ions and has demonstrated imaging capabilities with sub- 100-nm resolution. The virtual source size, angular intensity, mass spectra, and energy spread of the source have been determined with argon and xenon. This magnetically enhanced, inductively coupled plasmasource has exhibited a reduced brightness(Ī²r) of 5.4Ć10Ā³Amā»Ā²srā»Ā¹Vā»Ā¹, with a full width half maximum axial energy spread (ĪE) of 10eV when operated with argon. With xenon, Ī²r=9.1Ć10Ā³Amā»Ā²srā»Ā¹Vā»Ā¹ and ĪE=7eV. With these source parameters, an optical column with sufficient demagnification is capable of forming a sub-25-nm spot size at 30keV and 1pA. The angular intensity of this source is nominally three orders of magnitude greater than a LMIS making the source more amenable to creating high current focused beams, in the regime where spherical aberration dominates the LMIS-FIB. The source has been operated on a two lens ion column and has demonstrated a current density that exceeds that of the LMIS-FIB for current greater than 50nA. Source lifetime and current stability are excellent with inert and reactive gases. Additionally, it should be possible to improve both the brightness and energy spread of this source, such that the (Ī²r/ĪEā) figure-of-merit could be within an order of magnitude of a LMIS
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