1,078 research outputs found
Dynamic general equilibrium analysis of improved weed management in Australia's winter cropping systems
A recent analysis indicated that the direct financial cost of weeds to Australia’s winter grain sectorwas approximately 50m of R&D spread over five years is targeted at reducing the additional costs and reduced yields arising from weeds in various broadacre crops. Following this R&D effort, one-tenth of the losses arising from weeds is temporarily eliminated, with a diminishing benefit in succeeding years. At the national level, there is a welfare increase of $700m in discounted net present value terms. The regions with relatively high concentrations of winter crops experience small temporary macroeconomic gains.CGE modelling, dynamics, weed management, Crop Production/Industries,
Asymptotic description of solutions of the exterior Navier Stokes problem in a half space
We consider the problem of a body moving within an incompressible fluid at
constant speed parallel to a wall, in an otherwise unbounded domain. This
situation is modeled by the incompressible Navier-Stokes equations in an
exterior domain in a half space, with appropriate boundary conditions on the
wall, the body, and at infinity. We focus on the case where the size of the
body is small. We prove in a very general setup that the solution of this
problem is unique and we compute a sharp decay rate of the solution far from
the moving body and the wall
Investigations on the slope efficiency of a pulsed 2.8-µm Er3+:LiYF4 laser
A slope efficiency of 40% from an Er3+:LiYF4 laser is demonstrated under pulsed Ti:sapphire pumping at 973 nm. With reduction of the pump-pulse duration a significant decrease of the slope efficiency and an increase of the threshold is observed in the experiment and confirmed with high accuracy in a computer simulation. This behavior is due to interionic upconversion from the lower laser level, which leads to energy recycling into the upper laser level. The upconversion rate is negative at threshold but increases strongly with rising pump pulse energy, thus enhancing the slope efficiency. The conditions are derived that are necessary for achieving the high slope efficiency of the energy-recycling regime
Performance of a Novel Handheld Bioelectrical Impedance Device for Assessing Muscle Mass in Older Inpatients.
OBJECTIVES
To investigate practicality and repeatability of a handheld compared to a state-of-the-art multisegmental bioelectrical impedance analysis (BIA) device to facilitate screening of sarcopenia in older inpatients.
DESIGN AND SETTING
Cross-sectional study in a geriatric rehabilitation hospital.
PARTICIPANTS
207 inpatients aged 70+.
MEASUREMENTS
In a first phase, appendicular skeletal muscle mass index (ASMI) was measured using the handheld Biody xpertZm II BIA device (n=100). In a second phase, ASMI was obtained using the multisegmental Biacorpus RX 4004M device (n=107). Repeatability of BIA devices was compared in subgroups of patients (handheld BIA device: n=36, multisegmental BIA device: n=46) by intra-class correlation (ICC) and Bland-Altman plots.
RESULTS
Overall, measurement failure was seen in 31 patients (31%) tested with the handheld BIA device compared to one patient (0.9%) using the multisegmental BIA device (p<0.001). Main reasons for measurement failure were inability of patients to adopt the position necessary to use the handheld BIA device and device failure. The mean difference of two ASMI measurements in the same patient was 0.32 (sd 0.85) using the handheld BIA device compared to 0.02 kg/m2 (sd 0.07) using the multisegmental device (adjusted mean difference between both groups -0.35, 95% confidence interval (CI) -0.61 to -0.09 kg/m2). Congruently, Bland-Altman plots showed poor agreement with the handheld compared to the multisegmental BIA device.
CONCLUSION
The handheld BIA device is neither a practical nor reliable device for assessing muscle mass in older rehabilitation inpatients
A Renormalization Group for Hamiltonians: Numerical Results
We describe a renormalization group transformation that is related to the
breakup of golden invariant tori in Hamiltonian systems with two degrees of
freedom. This transformation applies to a large class of Hamiltonians, is
conceptually simple, and allows for accurate numerical computations. In a
numerical implementation, we find a nontrivial fixed point and determine the
corresponding critical index and scaling. Our computed values for various
universal constants are in good agreement with existing data for
area-preserving maps. We also discuss the flow associated with the nontrivial
fixed point.Comment: 11 Pages, 2 Figures. For future updates, check
ftp://ftp.ma.utexas.edu/pub/papers/koch
- …