5,326 research outputs found
New degradation compounds from lignocellulosic biomass pretreatment: routes for formation of potent oligophenolic enzyme inhibitors
In this study 26 new oligophenol cellulase inhibitors were discovered from wheat straw pretreatment liquors.</p
Few-body resonances of unequal-mass systems with infinite interspecies two-body s-wave scattering length
Two-component Fermi and Bose gases with infinitely large interspecies s-wave
scattering length exhibit a variety of intriguing properties. Among these
are the scale invariance of two-component Fermi gases with equal masses, and
the favorable scaling of Efimov features for two-component Bose gases and
Bose-Fermi mixtures with unequal masses. This paper builds on our earlier work
[D. Blume and K. M. Daily, arXiv:1006.5002] and presents a detailed discussion
of our studies of small unequal-mass two-component systems with infinite
in the regime where three-body Efimov physics is absent. We report on
non-universal few-body resonances. Just like with two-body systems on
resonance, few-body systems have a zero-energy bound state in free space and a
diverging generalized scattering length. Our calculations are performed within
a non-perturbative microscopic framework and investigate the energetics and
structural properties of small unequal-mass two-component systems as functions
of the mass ratio , and the numbers and of heavy and
light atoms. For purely attractive Gaussian two-body interactions, we find that
the and systems exhibit three-body and four-body
resonances at mass ratios and 10.4(2), respectively. The
three- and four-particle systems on resonance are found to be large. This
suggests that the corresponding wave function has relatively small overlap with
deeply-bound dimers, trimers or larger clusters and that the three- and
four-body systems on resonance have a comparatively long lifetime. Thus, it
seems feasible that the features discussed in this paper can be probed
experimentally with present-day technology.Comment: 17 pages, 17 figure
Aeolian transport layer
We investigate the airborne transport of particles on a granular surface by
the saltation mechanism through numerical simulation of particle motion coupled
with turbulent flow. We determine the saturated flux and show that its
behavior is consistent with a classical empirical relation obtained from wind
tunnel measurements. Our results also allow to propose a new relation valid for
small fluxes, namely, , where and
are the shear and threshold velocities of the wind, respectively, and
the scaling exponent is . We obtain an expression for the
velocity profile of the wind distorted by the particle motion and present a
dynamical scaling relation. We also find a novel expression for the dependence
of the height of the saltation layer as function of the wind velocity.Comment: 4 pages, 4 figure
Spin Squeezing in the Ising Model
We analyze the collective spin noise in interacting spin systems. General
expressions are derived for the short time behaviour of spin systems with
general spin-spin interactions, and we suggest optimum experimental conditions
for the detection of spin squeezing. For Ising models with site dependent
nearest neighbour interactions general expressions are presented for the spin
squeezing parameter for all times. The reduction of collective spin noise can
be used to verify the entangling powers of quantum computer architectures based
on interacting spins.Comment: 7 pages, including 3 figure
HortiBot: A System Design of a Robotic Tool Carrier for High-tech Plant Nursing
Danish organic outdoor gardeners today use 50-300 hours per hectare for manual weeding.
Through automatic controlling of an existing commercial machine this often heavy and costconsuming
weeding will be eliminated. At the same time, a fully-automatic registration of field
activities will contribute to the efficient implementation of EU directive 178/2002 concerning
traceability in the primary production and thereby enhance the food-safety in the production
chain. A radio controlled slope mower is equipped with a new robotic accessory kit. This
transforms it into a tool carrier (HortiBot) for high-tech plant nursing for e.g. organic grown
vegetables. The HortiBot is capable of passing over several parcels with visible rows
autonomously based on a new commercial row detection system from Eco-Dan a/s, Denmark.
This paper presents the solutions chosen for the HortiBot with regard to hardware, mechanicalelectrical
interfaces and software. Further, the principles from a Quality Function Deployment
(QFD) analysis was used to carry out the solicitation, evaluation and selection of most qualified
design parameters and specifications attained to a horticultural robotic tool carrier. The QFD
analysis provided a specific measure to evaluate each selected parameter in terms of satisfying
user requirements and operational performance aspects. Based on a combination of importance
rating and competitive priority ratings important user requirements include easy adaptation to
field conditions in terms of row distance and parcel size, profitability, minimum crop damage
during operation, and reliability. Lesser importance was attributed to affection value, attractive
look, the possibility of out of season usage, and the use of renewable energy
Structure of boson systems beyond the mean-field
We investigate systems of identical bosons with the focus on two-body
correlations. We use the hyperspherical adiabatic method and a decomposition of
the wave function in two-body amplitudes. An analytic parametrization is used
for the adiabatic effective radial potential. We discuss the structure of a
condensate for arbitrary scattering length. Stability and time scales for
various decay processes are estimated. The previously predicted Efimov-like
states are found to be very narrow. We discuss the validity conditions and
formal connections between the zero- and finite-range mean-field
approximations, Faddeev-Yakubovskii formulation, Jastrow ansatz, and the
present method. We compare numerical results from present work with mean-field
calculations and discuss qualitatively the connection with measurements.Comment: 26 pages, 6 figures, submitted to J. Phys. B. Ver. 2 is 28 pages with
modified figures and discussion
Early motor developmental milestones and level of neuroticism in young adulthood:a 23-year follow-up study of the Copenhagen Perinatal Cohort
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