72,252 research outputs found
An evaluation of the effects of blue crab (Callinectes sapidus) behavior on the efficacy of crab pots as a tool for estimating population abundance
Crab traps have been used extensively in studies on the population dynamics of blue crabs to provide estimates of catch per unit of effort; however, these estimates have been
determined without adequate consideration of escape rates. We examined the ability of the blue crab (Callinectes
sapidus) to escape crab pots and the possibility that intraspecific crab interactions have an effect on catch
rates. Approximately 85% of crabs that entered a pot escaped, and 83% of crabs escaped from the bait chamber
(kitchen). Blue crabs exhibited few aggressive behavioral interactions in and around the crab pot and were
documented to move freely in and out of the pot. Both the mean number and size of crabs caught were significantly
smaller at deeper depths. Results from this study show that
current estimates of catch per unit of effort may be biased given the high escape rate of blue crabs documented
in this study. The results of this paper provide a mechanistic view of trap efficacy, and reveal crab behavior in and around commercial crab pots
Strengthening Employment-Based Pensions in Japan
We investigate how the Japanese pension market for funded employment-based pensions is changing and how it might be strengthened in order to better serve one of the most rapidly aging populations in the world. Public and private pensions in Japan are estimated to hold around US$3 trillion, making that system the second largest globally after the United States. However, unfavorable economic developments have cut sharply cut into asset values, and the weak economy is undermining traditional lifetime employment contracts. Recent legislation permitting the establishment of defined contribution plans in Japan may provide new employer-sponsored retirement plan opportunities. We first describe the Japanese pension system at the end of the 20th century and provide an overview and evaluation of the changes in the pension arena emerging from the 2001 legislation. Next we show that important design questions remain to be answered, if Japanese employment-based pensions are to be reformed and modernized. Finally we indicate lessons gleaned from recent changes in US pension plans.
The administration of research. An interpretive summary of the Proceedings of the National Conference on the Administration of Research, 1947-1964
Research management and administration - summary of conference proceeding
Generation of twin Fock states via transition from a two-component Mott insulator to a superfluid
We propose the dynamical creation of twin Fock states, which exhibit
Heisenberg limited interferometric phase sensitivities, in an optical lattice.
In our scheme a two-component Mott insulator with two bosonic atoms per lattice
site is melted into a superfluid. This process transforms local correlations
between hyperfine states of atom pairs into multi-particle correlations
extending over the whole system. The melting time does not scale with the
system size which makes our scheme experimentally feasible.Comment: 4 pages, 4 figure
Nature of the spin liquid state of the Hubbard model on honeycomb lattice
Recent numerical work (Nature 464, 847 (2010)) indicates the existence of a
spin liquid phase (SL) that intervenes between the antiferromagnetic and
semimetallic phases of the half filled Hubbard model on a honeycomb lattice. To
better understand the nature of this exotic phase, we study the quantum
spin model on the honeycomb lattice, which provides an effective
description of the Mott insulating region of the Hubbard model. Employing the
variational Monte Carlo approach, we analyze the phase diagram of the model,
finding a phase transition between antiferromagnet and an unusual SL
state at , which we identify as the SL phase of the
Hubbard model. At higher we find a transition to a
dimerized state with spontaneously broken rotational symmetry.Comment: 5 pages, 6 figure
H-NMR spin-echo measurements of the static and dynamic spin properties in -(BETS)FeCl
H-NMR spin-echo measurements of the spin-echo decay with a
decay rate 1/ and the frequency shift under applied
magnetic field = 9 T along the a-axis over a temperature
range 2.0180 K are reported for a single crystal of the organic conductor
-(BETS)FeCl. It provides the spin dynamic and static
properties in the paramagnetic metal (PM) and antiferromagnetic insulator (AFI)
states as well as across the PMAFI phase transition. A large slow beat
structure in the spin-echo decay is observed with a typical beat frequency of
7 kHz and it varies across the spectrum. Its origin is attributed to
the HH dipole interactions rather than to the much larger
dipolar field contribution from the Fe electrons (spin = 5/2). A
simple phenomenological model provides an excellent fit to the data. The
dominant H-NMR frequency shift comes from the dipolar field from the 3d
Fe ions, and the Fe Fe exchange interactions ()
( includes the dd exchange interactions through the electrons)
have a substantial effect to the local field at the proton sites expecially at
low temperatures. A good fit is obtained with = - 1.7 K. The data of
the spin-echo decay rate 1/ indicates that there is a significant change
in the slow fluctuations of the local magnetic field at the H-sites on
traversing the PM to AFI phase. This evidence supports earlier reports that the
PMAFI phase transition in -(BETS)FeCl is driven
magnetically and first order.Comment: 9 pages, 10 figures, resubmitted to Phys. Rev. B in response to
comments of Editor and reviewers on March 23, 200
ICT as learning media and research instrument: What eResearch can offer for those who research eLearning?
Studentsâ interactions in digital learning environments are distributed over time and space, and many aspects of eLearning phenomenon cannot be investigated using traditional research approaches. At the same time, the possibility to collect digital data about studentsâ online interactions and learning opens a range of new opportunities to use ICT as research tool and apply new research approaches. This symposium brings together some of the recent advancements in the area of ICT-enhanced research and aims to discuss future directions for methodological innovation in this area. The session will include four presentations that will explore different directions of ICT use for eLearning research
Ecosystem Benefits of Invasive Annual Grass Removal
Invasive winter annual grasses (IAGs) are altering rangeland ecosystems across millions of hectares in the western US. These winter annuals outcompete native plants for soil moisture and nutrients, leading to devastating impacts on ecosystem functions. The IAG seedbank is short-lived and often does not persist beyond 3 years. Past tools for IAG control have only provided short-term control or caused injury to the native plant community, making it difficult for researchers to assess the ecosystem benefits of IAG removal. A newer herbicide option, indaziflam, provides IAG control for three or more years. Indaziflamâs extended soil residual control and tolerance of perennial species creates the opportunity to deplete the IAG seedbank, allowing time for remnant plant communities to recover. Research has been conducted on sites across the western US where IAGs were managed using indaziflam. Long-term IAG management has led to increases in native plant cover and biomass as well as greater biodiversity within the native plant community. The shift from an IAG dominated community to a healthy native plant community has resulted in improved pollinator and wildlife habitat in these sites. By changing the management paradigm to target the IAG seedbank, land managers can achieve long-term restoration
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