20,277 research outputs found
The synthesis of a symmetrically substituted α-octa(isopentoxy)anthralocyanine
α-Octa(isopentoxy)anthralocyanine has been synthesized and is found to have an unprecedented low-energy Q-band absorption and a low first oxidation potential
Imputing historical statistics, soils information, and other land-use data to crop area
In foreign crop condition monitoring, satellite acquired imagery is routinely used. To facilitate interpretation of this imagery, it is advantageous to have estimates of the crop types and their extent for small area units, i.e., grid cells on a map represent, at 60 deg latitude, an area nominally 25 by 25 nautical miles in size. The feasibility of imputing historical crop statistics, soils information, and other ancillary data to crop area for a province in Argentina is studied
Enhanced reverse saturable absorption and optical limiting in heavy-atom-substituted phthalocyanines
The reverse saturable absorption and the optical-limiting response of metal phthalocyanines can be enhanced by use of the heavy-atom effect. Phthalocyanines containing heavy-metal atoms, such as In, Sn, and Pb, show a nearly factor-of-2 enhancement in the ratio of effective excited-state to ground-state absorption cross sections compared with those containing lighter atoms, such as Al and Si. In an f/8 optical geometry, homogeneous solutions of heavy-metal phthalocyanines, at 30% linear transmission, limit 8-ns 532-nm laser pulses to ≤ 3 µJ the energy for 50% probability of eye damage) for incident energies as high as 800 µJ
A Study of Linear Approximation Techniques for SAR Azimuth Processing
The application of the step transform subarray processing techniques to synthetic aperture radar (SAR) was studied. The subarray technique permits the application of efficient digital transform computational techniques such as the fast Fourier transform to be applied while offering an effective tool for range migration compensation. Range migration compensation is applied at the subarray level, and with the subarray size based on worst case range migration conditions, a minimum control system is achieved. A baseline processor was designed for a four-look SAR system covering approximately 4096 by 4096 SAR sample field every 2.5 seconds. Implementation of the baseline system was projected using advanced low power technologies. A 20 swath is implemented with approximately 1000 circuits having a power dissipation of from 70 to 195 watts. The baseline batch step transform processor is compared to a continuous strip processor, and variations of the baseline are developed for a wide range of SAR parameters
CALL BROADCASTING AND AUTOMATED RECORDERS AS TOOLS FOR ANURAN SURVEYS IN A SUBARCTIC TUNDRA LANDSCAPE
Relatively little is known about population ecology of anurans in arctic and subarctic tundra regions, in part because it is difficult to survey anurans in these landscapes. Anuran survey protocols developed for temperate regions have limited applicability in arctic and subarctic tundra landscapes, which may lack roads and vehicle access, and experience variable and inclement weather during short anuran breeding seasons. To evaluate approaches to address some of the limitations of surveying anurans in tundra landscapes, we assessed the effectiveness of using breeding call broadcasts to increase detection of Boreal Chorus Frogs (Pseudacris maculata) and Wood Frogs (Lithobates sylvaticus) near Cape Churchill, Manitoba, Canada. We also evaluated how counts of anurans derived from automated audio recorders compared with those obtained simultaneously by observers. We detected on average 0.4 additional Wood Frogs per survey when we broadcasted calls (x = 0.82, SD = 1.38), an increase of > 40% compared to surveys without broadcasts (x = 1.24, SD = 1.51; Wilcoxon test; Z = 2.73, P = 0.006). In contrast, broadcasting Boreal Chorus Frog calls did not increase the number of chorus frog detections (Wilcoxon test; Z < 0.001, P > 0.90). Detections of Wood Frogs in a 100-m radius were lower via automated recorders (x = 0.60, SD = 0.87 SD) than by observers during simultaneous surveys (x = 0.96, SD = 1.27 Z = 2.07, P = 0.038), but those of Boreal Chorus Frogs were not different (x = 1.72, SD = 1.31;x = 1.44, SD = 1.5; Z = 1.55, P > 0.121). Our results suggest that broadcasting calls can increase detection of Wood Frogs, and that automated recorders are useful in detecting both Wood Frogs and Boreal Chorus Fogs in arctic and subarctic tundra landscapes
Initial bound state studies in light-front QCD
We present the first numerical QCD bound state calculation based on a
renormalization group-improved light-front Hamiltonian formalism. The QCD
Hamiltonian is determined to second order in the coupling, and it includes
two-body confining interactions. We make a momentum expansion, obtaining an
equal-time-like Schrodinger equation. This is solved for quark-antiquark
constituent states, and we obtain a set of self-consistent parameters by
fitting B meson spectra.Comment: 38 pages, latex, 5 latex figures include
Similarity Renormalization Group for Nucleon-Nucleon Interactions
The similarity renormalization group (SRG) is based on unitary
transformations that suppress off-diagonal matrix elements, forcing the
hamiltonian towards a band-diagonal form. A simple SRG transformation applied
to nucleon-nucleon interactions leads to greatly improved convergence
properties while preserving observables, and provides a method to consistently
evolve many-body potentials and other operators.Comment: 5 pages, 6 figures (8 figure files); references updated and
acknowledgment adde
Pressure study of nematicity and quantum criticality in SrRuO for an in-plane field
We study the relationship between the nematic phases of SrRuO and
quantum criticality. At ambient pressure, one nematic phase is associated with
a metamagnetic quantum critical end point (QCEP) when the applied magnetic
field is near the \textit{c}-axis. We show, however, that this metamagnetic
transition does not produce the same nematic signatures when the QCEP is
reached by hydrostatic pressure with the field applied in the
\textit{ab}-plane. Moreover, a second nematic phase, that is seen for field
applied in the \textit{ab}-plane close to, but not right at, a second
metamagnetic anomaly, persists with minimal change to the highest applied
pressure, 16.55 kbar. Taken together our results suggest that metamagnetic
quantum criticality may not be necessary for the formation of a nematic phase
in SrRuO
Perturbative Tamm-Dancoff Renormalization
A new two-step renormalization procedure is proposed. In the first step, the
effects of high-energy states are considered in the conventional (Feynman)
perturbation theory. In the second step, the coupling to many-body states is
eliminated by a similarity transformation. The resultant effective Hamiltonian
contains only interactions which do not change particle number. It is subject
to numerical diagonalization. We apply the general procedure to a simple
example for the purpose of illustration.Comment: 20 pages, RevTeX, 10 figure
Maine Festival Hymn : For Chorus and Orchestra
https://digitalcommons.library.umaine.edu/mmb-me/1136/thumbnail.jp
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