1,805 research outputs found
Carnivorous Spadefoot (Spea bombifrons Cope) Tadpoles and Fairy Shrimp in Western Iowa
Amphibian larval polymorphisms, rarely found in the Midwest, are more common in arid western regions. We have discovered that Plains spadefoot toad, Spea bombifrons Cope, tadpoles occur as carnivorous and omnivorous morphological forms in flooded soybean and corn fields on the Missouri River flood plain of western Iowa. Carnivores have longer snouts, larger beaks with an upper cusp and lower notch, shorter intestines with fewer loops than the omnivores, and they feed on fairy shrimp. A similar polymorphism in Spea multiplicata Cope enhances survival in the desert because the carnivore develops faster after consuming fairy shrimp and is able to metamorphose in rapidly drying ponds. However, the omnivore develops slower in deeper ponds, stores more fat and has better postmetamorphic success. Fairy shrimp ingestion triggers development of the S. multiplicata carnivores, but whether this is also true for S. bomifrons remains to be seen. Distributions and abundance of both carnivorous S. bombifrons tadpoles and fairy shrimp need to be determined across the Great Plains and in Iowa
Identifying and accounting for the Coriolis Effect in satellite NO2 observations and emission estimates
Recent developments in atmospheric remote sensing from satellites have made it possible to resolve daily emission plumes from industrial point sources, around the globe. Wind rotation aggregation coupled with statistical fitting is commonly used to extract emission estimates from these observations. These methods are used here to investigate how the Coriolis Effect influences the trajectory of observed emission plumes, and to assess the impact of this influence on satellite derived emission estimates. Of the 17 industrial sites investigated, nine showed the expected curvature for the hemisphere they reside in. Five showed no or negligible curvature, and two showed opposing or unusual curvature. The sites which showed conflicting curvature all reside in topographically diverse regions, where strong meso-gamma scale (2–20 km) turbulence dominates over larger synoptic circulation patterns. For high curvature cases the assumption that the wind-rotated plume aggregate is symmetrically distributed across the downwind axis breaks down, which impairs the quality of statistical fitting procedures. Using NOx emissions from Matimba power station as a test case, not compensating for Coriolis curvature resulted in an10 underestimation of ∼ 9 % on average for years 2018 to 2021. This study is the first formal observation of the Coriolis Effect and its influence on satellite observed emission plumes, and highlight both the variability of emission calculation methods and the need for a standardised scheme for this data to act as evidence for regulators.</p
Double-layer shocks in a magnetized quantum plasma
The formation of small but finite amplitude electrostatic shocks in the
propagation of quantum ion-acoustic waves (QIAWs) obliquely to an external
magnetic field is reported in a quantum electron-positron-ion (e-p-i) plasma.
Such shocks are seen to have double-layer (DL) structures composed of the
compressive and accompanying rarefactive slow-wave fronts. Existence of such DL
shocks depends critically on the quantum coupling parameter associated with
the Bohm potential and the positron to electron density ratio . The
profiles may, however, steepen initially and reach a steady state with a number
of solitary waves in front of the shocks. Such novel DL shocks could be a good
candidate for particle acceleration in intense laser-solid density plasma
interaction experiments as well as in compact astrophysical objects, e.g.,
magnetized white dwarfs.Comment: 4 pages, 1 figure (to appear in Physical Review E
Effect of interactions on vortices in a nonequilibrium polariton condensate
We demonstrate the creation of vortices in a macroscopically occupied polariton state formed in a semiconductor microcavity. A weak external laser beam carrying orbital angular momentum (OAM) is used to imprint a vortex on the condensate arising from the polariton optical parametric oscillator (OPO). The vortex core radius is found to decrease with increasing pump power, and is determined by polariton-polariton interactions. As a result of OAM conservation in the parametric scattering process, the excitation consists of a vortex in the signal and a corresponding antivortex in the idler of the OPO. The experimental results are in good agreement with a theoretical model of a vortex in the polariton OPO
Constructing Qubits in Physical Systems
The notion of a qubit is ubiquitous in quantum information processing. In
spite of the simple abstract definition of qubits as two-state quantum systems,
identifying qubits in physical systems is often unexpectedly difficult. There
are an astonishing variety of ways in which qubits can emerge from devices.
What essential features are required for an implementation to properly
instantiate a qubit? We give three typical examples and propose an operational
characterization of qubits based on quantum observables and subsystems.Comment: 16 pages, no figures; IoP LaTeX2e style. Submitted to J. Phys. A:
Math. Ge
Quantum-mechanical calculation of Stark widths of Ne VII n=3, transitions
The Stark widths of the Ne VII 2s3s-2s3p singlet and triplet lines are
calculated in the impact approximation using quantum-mechanical Convergent
Close-Coupling and Coulomb-Born-Exchange approximations. It is shown that the
contribution from inelastic collisions to the line widths exceeds the elastic
width contribution by about an order of magnitude. Comparison with the line
widths measured in a hot dense plasma of a gas-liner pinch indicates a
significant difference which may be naturally explained by non-thermal Doppler
effects from persistent implosion velocities or turbulence developed during the
pinch implosion. Contributions to the line width from different partial waves
and types of interactions are discussed as well.Comment: 8 pages, 3 figures; accepted by Phys. Rev.
Multilingual gendered identities: female undergraduate students in London talk about heritage languages
In this paper I explore how a group of female university students, mostly British Asian and in their late teens and early twenties, perform femininities in talk about heritage languages. I argue that analysis of this talk reveals ways in which the participants enact âculturally intelligibleâ gendered subject positions. This frequently involves negotiating the norms of âheteronormativityâ, constituting femininity in terms of marriage, motherhood and maintenance of heritage culture and language, and âgirl powerâ, constituting femininity in terms of youth, sassiness, glamour and individualism. For these young women, I ask whether higher education can become a site in which they have the opportunities to explore these identifications and examine other ways of imagining the self and what their stories suggest about âdoing beingâ a young British Asian woman in London
Strange Decays of Nonstrange Baryons
The strong decays of excited nonstrange baryons into the final states Lambda
K, Sigma K, and for the first time into Lambda(1405) K, Lambda(1520) K,
Sigma(1385) K, Lambda K*, and Sigma K*, are examined in a relativized quark
pair creation model. The wave functions and parameters of the model are fixed
by previous calculations of N pi and N pi pi, etc., decays. Our results show
that it should be possible to discover several new negative parity excited
baryons and confirm the discovery of several others by analyzing these final
states in kaon production experiments. We also establish clear predictions for
the relative strengths of certain states to decay to Lambda(1405) K and
Lambda(1520) K, which can be tested to determine if a three-quark model of the
Lambda(1405) K is valid. Our results compare favorably with the results of
partial wave analyses of the limited existing data for the Lambda K and Sigma K
channels. We do not find large Sigma K decay amplitudes for a substantial group
of predicted and weakly established negative-parity states, in contrast to the
only previous work to consider decays of these states into the strange final
states Lambda K and Sigma K.Comment: 25 pages, 8 figures, RevTe
Masses of the 70- Baryons in Large Nc QCD
The masses of the negative parity 70-plet baryons are analyzed in large N_c
QCD to order 1/N_c and to first order in SU(3) symmetry breaking. The existing
experimental data are well reproduced and twenty new observables are predicted.
The leading order SU(6) spin-flavor symmetry breaking is small and, as it
occurs in the quark model, the subleading in 1/N_c hyperfine interaction is the
dominant source of the breaking. It is found that the Lambda(1405) and
Lambda(1520) are well described as three-quark states and spin-orbit partners.
New relations between splittings in different SU(3) multiplets are found.Comment: 11 pages; references were added and a couple of improvements to the
text were mad
Radiative decays: a new flavour filter
Radiative decays of the orbital excitations of the ,
and to the scalars , and are shown to
provide a flavour filter, clarifying the extent of glueball mixing in the
scalar states. A complementary approach to the latter is provided by the
radiative decays of the scalar mesons to the ground-state vectors ,
and . Discrimination among different mixing scenarios is strong.Comment: 12 pages, 1 table, 0 figure
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