3,384 research outputs found
Dispersal, Flight, and Diurnal Activity Patterns of Adult Southern Corn Billbugs (Coleoptera: Curculionidae)
Dispersal into cornfields, flight, and diurnal activity patterns of the adult southern com billbug (SCB), Sphenophorus callosus (Olivier), were studied in eastern North Carolina during 1979 and 1980. Com plant damage (an index of SCB density) in fields with different cropping histories was initially concentrated either on the field edge next to last year\u27s corn in rotated fields, or the edge next to the overwintering site in nonrotated fields. Although damage patterns and trapping studies suggested that SCB dispersal into fields was primarily by walking, SCB are capable of strong flight. Weevils of both the overwintered and summer generations were caught in flight traps. Diurnal activity patterns of adult SCB were often bimodal; peak numbers of adults were found on plants and caught in pitfall traps in late morning and mid- to late afternoon. Changes in adult activity appeared to be better explained by changes in temperature than by changes in light intensity. Least activity occurred when temperatures were above 30°C or below 20°C
Dispersal, Flight, and Diurnal Activity Patterns of Adult Southern Corn Billbugs (Coleoptera: Curculionidae)
Dispersal into cornfields, flight, and diurnal activity patterns of the adult southern com billbug (SCB), Sphenophorus callosus (Olivier), were studied in eastern North Carolina during 1979 and 1980. Com plant damage (an index of SCB density) in fields with different cropping histories was initially concentrated either on the field edge next to last year\u27s corn in rotated fields, or the edge next to the overwintering site in nonrotated fields. Although damage patterns and trapping studies suggested that SCB dispersal into fields was primarily by walking, SCB are capable of strong flight. Weevils of both the overwintered and summer generations were caught in flight traps. Diurnal activity patterns of adult SCB were often bimodal; peak numbers of adults were found on plants and caught in pitfall traps in late morning and mid- to late afternoon. Changes in adult activity appeared to be better explained by changes in temperature than by changes in light intensity. Least activity occurred when temperatures were above 30°C or below 20°C
Fact or fable: Increased wellbeing in voluntary simplicity
The value of a simple life has been espoused by writers and thinkers throughout time. In the modern era, it has been proposed as an antidote to modern stressors and as a path to wellbeing. The simple life — or voluntary simplicity as it has become known — is a lifestyle whose hallmark is reduced consumption. Personal growth and ecologically responsible behaviours are also integral components. If voluntary simplicity is a path to increased wellbeing, then society stands to benefit if the lifestyle becomes more widely adopted. This review asks the question, is there empirical evidence for an association between voluntary simplicity and improved wellbeing? Using a systematic approach, peer-reviewed literature regarding the wellbeing outcomes of simplifiers was located, resulting in four studies containing a total of 3,233 participants. A comparison of the four studies is given and the strengths and limitations of the present state of research in the area offered. It is concluded that the putative association between voluntary simplicity and improved wellbeing does exist, although important questions remain to be resolved by future research
Nonequilibrium dynamics of vortex arrest in a finite-temperature Bose-Einstein condensate
We perform finite-temperature dynamical simulations of the arrest of a
rotating Bose-Einstein condensate by a fixed trap anisotropy, using a
Hamiltonian classical-field method. We consider a quasi-two-dimensional
condensate containing a single vortex in equilibrium with a rotating thermal
cloud. Introducing an elliptical deformation of the trapping potential leads to
the loss of angular momentum from the system. We identify the condensate and
the complementary thermal component of the nonequilibrium field, and compare
the evolution of their angular momenta and angular velocities. By varying the
trap anisotropy we alter the relative efficiencies of the vortex-cloud and
cloud-trap coupling. For strong trap anisotropies the angular momentum of the
thermal cloud may be entirely depleted before the vortex begins to decay. For
weak trap anisotropies, the thermal cloud exhibits a long-lived steady state in
which it rotates at an intermediate angular velocity.Comment: 10 pages, 6 figures. v2: Minor changes in response to referee's
comments. To appear in PR
Quantum Dynamics of Three Coupled Atomic Bose-Einstein Condensates
The simplest model of three coupled Bose-Einstein Condensates (BEC) is
investigated using a group theoretical method. The stationary solutions are
determined using the SU(3) group under the mean field approximation. This
semiclassical analysis using the system symmetries shows a transition in the
dynamics of the system from self trapping to delocalization at a critical value
for the coupling between the condensates. The global dynamics are investigated
by examination of the stable points and our analysis shows the structure of the
stable points depends on the ratio of the condensate coupling to the
particle-particle interaction, undergoes bifurcations as this ratio is varied.
This semiclassical model is compared to a full quantum treatment, which also
displays the dynamical transition. The quantum case has collapse and revival
sequences superposed on the semiclassical dynamics reflecting the underlying
discreteness of the spectrum. Non-zero circular current states are also
demonstrated as one of the higher dimensional effects displayed in this system.Comment: Accepted to PR
Evaluation of Feeding Varying Levels of Wet Distillers Grains with Solubles as Compared to Dry Distilelrs Grains with Solubles to Finishing Steers
A study was conducted to determine the effects of implants and transportation on the metabolic status of feedlot steers. Steers (n = 28) were sorted by body weight, allocated into light or heavy blocks, and randomly assigned to one of two treatments. Treatments included non-implanted controls (CON) and steers implanted with Synovex Plus 70 d prior to harvest (IMP). Jugular blood and muscle biopsy samples (longissimus dorsi (LD) and semimembranosis (SM)) were collected 70 d post-implant, prior to transit. Steers were transported to Schuyler, NE, where blood and biopsy sampling was repeated. After harvest, carcass data were collected and muscle samples were taken from the LD, SM, Psoas Major (PM), and Illiacus (IL) muscles. Implanting increased (P \u3c 0.05) estradiol levels and improved live animal performance. Carcass weight and rib eye area were increased (P \u3c 0.05) in implanted steers. No dark cutters were found in either treatment. Pre-transit insulin/glucagon ratio and muscle glycogen levels did not differ (P \u3e 0.10) between treatments. Non-esterified fatty acid (NEFA) levels were reduced (P \u3c 0.05) in implanted steers pre-transit. Transit increased (P \u3c 0.05) NEFA levels, but had no effect (P \u3e 0.10) on insulin/glucagon ratio or muscle glycogen levels. Implanting did not affect (P \u3e 0.10) insulin/glucagon ratio, NEFA, or LD glycogen levels post-transit. Implanted steers had lower (P \u3c 0.05) glycogen levels in the SM than did non-implanted steers post-transit. Weight block affected (P \u3c 0.05) insulin and insulin/glucagon ratio levels, with steers in the light block having greater levels of each. Muscle pH and objective color (L*, a*, b*) of the LD were not biologically different between treatments. Implanted steers had greater (P \u3c 0.05) glycolytic potential values in the LD, and tended (P \u3c 0.10) to have higher L* values in the PM. Implanting increased (P \u3c 0.05) shear force of the LD. These data indicate that although implants affect bovine metabolism, other factors are necessary to cause a sufficient reduction in muscle glycogen and to produce a dark cutting carcass
Characteristics of Two-Dimensional Quantum Turbulence in a Compressible Superfluid
Under suitable forcing a fluid exhibits turbulence, with characteristics
strongly affected by the fluid's confining geometry. Here we study
two-dimensional quantum turbulence in a highly oblate Bose-Einstein condensate
in an annular trap. As a compressible quantum fluid, this system affords a rich
phenomenology, allowing coupling between vortex and acoustic energy.
Small-scale stirring generates an experimentally observed disordered vortex
distribution that evolves into large-scale flow in the form of a persistent
current. Numerical simulation of the experiment reveals additional
characteristics of two-dimensional quantum turbulence: spontaneous clustering
of same-circulation vortices, and an incompressible energy spectrum with
dependence for low wavenumbers and dependence for high
.Comment: 7 pages, 7 figures. Reference [29] updated for v
Quantum state of two trapped Bose-Einstein condensates with a Josephson coupling
We consider the precise quantum state of two trapped, coupled Bose Einstein
condensates in the two-mode approximation. We seek a representation of the
state in terms of a Wigner-like distribution on the two-mode Bloch sphere. The
problem is solved using a self-consistent rotation of the unknown state to the
south pole of the sphere. The two-mode Hamiltonian is projected onto the
harmonic oscillator phase plane, where it can be solved by standard techniques.
Our results show how the number of atoms in each trap and the squeezing in the
number difference depend on the physical parameters. Considering negative
scattering lengths, we show that there is a regime of squeezing in the relative
phase of the condensates which occurs for weaker interactions than the
superposition states found by Cirac et al% (quant-ph/9706034, 13 June 1997).
The phase squeezing is also apparent in mildly asymmetric trap configurations.Comment: 26 pages, 11 figure
C-Field Methods for Non-Equilibrium Bose Gases
We review c-field methods for simulating the non-equilibrium dynamics of
degenerate Bose gases beyond the mean-field Gross-Pitaevskii approximation. We
describe three separate approaches that utilise similar numerical methods, but
have distinct regimes of validity. Systems at finite temperature can be treated
with either the closed-system projected Gross-Pitaevskii equation (PGPE), or
the open-system stochastic projected Gross-Pitaevskii equation (SPGPE). These
are both applicable in quantum degenerate regimes in which thermal fluctuations
are significant. At low or zero temperature, the truncated Wigner projected
Gross-Pitaevskii equation (TWPGPE) allows for the simulation of systems in
which spontaneous collision processes seeded by quantum fluctuations are
important. We describe the regimes of validity of each of these methods, and
discuss their relationships to one another, and to other simulation techniques
for the dynamics of Bose gases. The utility of the SPGPE formalism in modelling
non-equilibrium Bose gases is illustrated by its application to the dynamics of
spontaneous vortex formation in the growth of a Bose-Einstein condensate.Comment: 7 pages, 1 figure. Unedited version of chapter to appear in Quantum
Gases: Finite Temperature and Non-Equilibrium Dynamics (Vol. 1 Cold Atoms
Series). N.P. Proukakis, S.A. Gardiner, M.J. Davis and M.H. Szymanska, eds.
Imperial College Press, London (in press). See
http://www.icpress.co.uk/physics/p817.html v2: Added arXiv cross-reference
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