3,012 research outputs found
Abundance and Habitat Use of Winter Raptors on a Reclaimed Surface Mine in Southeastern Ohio
Author Institution: Department of Biology, Muskingum UniversityNumerous studies have documented the benefits of reclaimed surface mines to breeding grassland birds, but few studies have focused on the use of such grasslands by winter raptors. I surveyed birds of prey along a driving transect on and around a 3,700 ha reclaimed surface mine in east-central Ohio from early January through mid-April 2009. My objective was to use these survey data to assess the relative abundance of migratory and winter resident raptors, as well as to examine potential habitat associations, perching preferences and morning versus afternoon activity patterns in each species. I sighted 382 total birds; red-tailed (Buteo jamaicensis) and rough-legged hawks (B. lagopus) had the greatest index of relative abundance followed by American kestrels (Falco sparverius) and northern harriers (Circus cyaneus). Numbers of rough-legged hawks, the only purely migratory species in
this region, declined from January through April, while numbers of red-tailed hawks and harriers increased. Rough-legged hawks, kestrels and harriers were found in open grasslands at a rate greater than expected by chance alone, whereas red-tailed hawks were found disproportionately more often along forest edges. Most rough-legged hawks and harriers were observed soaring rather than perched, while approximately equal numbers of red-tailed hawks were observed soaring or perched in large trees. Most kestrels
were observed on utility wires or in small trees. That moderate to high numbers of obligate grassland raptors were observed in this study, support previous findings that reclaimed surface mines provide important winter habitat for these species
Use of a Reclaimed Stripmine by Grassland Nesting Birds in East-Central Ohio
Author Institution: Biology Department, Muskingum CollegeDuring the 1997-1998 breeding seasons the author examined the nesting success of grassland birds on plots that were mowed prior to the onset of nesting and on unmowed plots on a 3,700 ha reclaimed stripmine in east-central Ohio. Grasshopper sparrows (Ammodramus savannarum), eastern meadowlarks (Sturnella magnci), red-winged blackbirds (Agelaius pboeniceus^), Henslow's sparrows (A. henslowiO, and bobolinks (Dolichonyx oryzivorus^ were the most abundant nesting species on the reclaimed stripmine. No short-eared owl (Asio JTammeus}, Henslow's sparrow, bobolink, or mallard (Anas platyrhynchos) nests were located on the mowed plots. Significantly more nests of all species combined (P 0.05). These data suggest that early season mowing is detrimental to some grassland bird species on this reclaimed stripmine since it precludes early nesting; however, it appears that Henslow's, savannah, and grasshopper sparrows, and other uncommon or sporadic grassland breeders in Ohio, are benefiting from this expansive, reclaimed surface mine
Quantum Tunneling Detection of Two-photon and Two-electron Processes
We analyze the operation of a quantum tunneling detector coupled to a
coherent conductor. We demonstrate that in a certain energy range the output of
the detector is determined by two-photon processes, two-electron processes and
the interference of the two. We show how the individual contributions of these
processes can be resolved in experiments.Comment: 4 pages, 4 figure
Abundance and Habitat Associations of Winter and Spring Birds on a Reclaimed Surface Mine (The Wilds) in Ohio, USA
Several studies have examined how grassland birds use reclaimed surface mines during the breeding season, but few studies have documented how these birds use these areas during the winter and early spring months. Using point counts, birds occupying a reclaimed surface-mine site in southeastern Ohio were surveyed from late December 2020 to April 2021. The primary objective was to document bird abundance and species richness across a temporal gradient spanning from late December 2020 through April 2021. Additionally, bird species composition was examined in habitat patches dominated by cool-season plants and in a single warm-season plot dominated by switchgrass (Panicum virgatum). A total of 1,452 bird sightings were made consisting of 40 species in 7 orders. Songbirds (order Passeriformes) comprised 60% of all sightings, and most of these (53%) were Red-winged Blackbirds (Agelaius phoeniceus), Eastern Meadowlarks (Sturnella magna), and Song Sparrows (Melospiza melodia). Thirty-nine species were observed on cool-season sites versus 13 species in the switchgrass plot. Species including returning Eastern Meadowlarks, Henslow's Sparrows (Centronyx henslowii), and Field Sparrows (Spizella pusilla) were common on the cool-season plots, but uncommon or absent in the switchgrass plot. Conversely, the switchgrass plot had more wintering American Tree Sparrows (Spizelloides arborea) and returning Swamp Sparrows (Melospiza georgiana). Return rates of long-distance migratory species fell within the time frames for these species as obtained from previous studies in this region. The diverse habitat structure of the cool-season portions of this study site attracted some winter species, including birds of prey, as well as several returning migratory species
Tunneling into Multiwalled Carbon Nanotubes: Coulomb Blockade and Fano Resonance
Tunneling spectroscopy measurements of single tunnel junctions formed between
multiwalled carbon nanotubes (MWNTs) and a normal metal are reported. Intrinsic
Coulomb interactions in the MWNTs give rise to a strong zero-bias suppression
of a tunneling density of states (TDOS) that can be fitted numerically to the
environmental quantum-fluctuation (EQF) theory. An asymmetric conductance
anomaly near zero bias is found at low temperatures and interpreted as Fano
resonance in the strong tunneling regime.Comment: 4 pages, 4 figure
Direct access to quantum fluctuations through cross-correlation measurements
Detection of the quantum fluctuations by conventional methods meets certain
obstacles, since it requires high frequency measurements. Moreover, quantum
fluctuations are normally dominated by classical noise, and are usually further
obstructed by various accompanying effects such as a detector backaction. In
present work, we demonstrate that these difficulties can be bypassed by
performing the cross-correlation measurements. We propose to use a pair of
two-level detectors, weakly coupled to a collective mode of an electric
circuit. Fluctuations of the current source accumulated in the collective mode
induce stochastic transitions in the detectors. These transitions are then read
off by quantum point contact (QPC) electrometers and translated into two
telegraph processes in the QPC currents. Since both detectors interact with the
same collective mode, this leads to a certain fraction of the correlated
transitions. These correlated transitions are fingerprinted in the
cross-correlations of the telegraph processes, which can be detected at zero
frequency, i.e., with a long time measurements. Concerning the dependance of
the cross-correlator on the detectors' energy splittings, the most interesting
region is at the degeneracy points, where it exhibits a sharp non-local
resonance, that stems from higher order processes. We find that at certain
conditions the main contribution to this resonance comes from the quantum
noise. Namely, while the resonance line shape is weakly broadened by the
classical noise, the height of the peak is directly proportional to the square
of the quantum component of the noise spectral function.Comment: Added discussion of the time scales in the introduction and one
figure. 14 pages, 8 figure
Low noise buffer amplifiers and buffered phase comparators for precise time and frequency measurement and distribution
Extremely low noise, high performance, wideband buffer amplifiers and buffered phase comparators were developed. These buffer amplifiers are designed to distribute reference frequencies from 30 KHz to 45 MHz from a hydrogen maser without degrading the hydrogen maser's performance. The buffered phase comparators are designed to intercompare the phase of state of the art hydrogen masers without adding any significant measurement system noise. These devices have a 27 femtosecond phase stability floor and are stable to better than one picosecond for long periods of time. Their temperature coefficient is less than one picosecond per degree C, and they have shown virtually no voltage coefficients
Policy Practitioners’ Accounts of Evidence-Based Policy Making: The Case of Universal Credit
This paper draws on insider accounts from UK Department for Work and Pensions (DWP) officials to analyse the relationship between evidence and policy making at a time of rapid policy development relating to Universal Credit (UC). The paper argues, firstly, that evidence selection within the DWP was constrained by the overarching austerity paradigm, which constituted a Zeitgeist and had a significant bearing on the evidence selection and translation process, sharpening the focus of policy officials and analysts on the primacy of quantitative evidence when advising Ministers. Secondly, while methodological preferences (or an ‘evidence hierarchy’) impacted on evidence selection, this was not as significant as practitioners’ perceived capabilities to handle and develop evidence for policy. These capabilities were linked to departmental structures and constrained by political feasibility. Together, these dimensions constituted a significant filtration mechanism determining the kinds of evidence that were selected for policy development and those omitted, particularly in relation to UC. The paper contributes to debates about the contemporary role of evidence in policymaking and the potential of the relationship between future evidence production and use
Lissajous curves and semiclassical theory: The two-dimensional harmonic oscillator
The semiclassical treatment of the two-dimensional harmonic oscillator
provides an instructive example of the relation between classical motion and
the quantum mechanical energy spectrum. We extend previous work on the
anisotropic oscillator with incommensurate frequencies and the isotropic
oscillator to the case with commensurate frequencies for which the Lissajous
curves appear as classical periodic orbits. Because of the three different
scenarios depending on the ratio of its frequencies, the two-dimensional
harmonic oscillator offers a unique way to explicitly analyze the role of
symmetries in classical and quantum mechanics.Comment: 9 pages, 3 figures; to appear in Am. J. Phy
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