4,652 research outputs found
Handing Over the Reins: A Comparative Study of Intergenerational Farm Transfers in England, France and Canada
One of the most critical stages in the development of any family business is the transfer of its ownership and control to the next generation. However, the process by which this transfer is achieved in farming has been one of the least-researched facets of farm business management. This paper draws on an on-going research project which seeks to remedy this omission. Comparable data for a total of 3,500 farms in England, France and Canada has been analysed to provide a portrait of the main features of the process in which the older generation retires from the farm while the younger generation takes over its ownership and management. The paper begins by defining the three distinct, but interrelated, processes of inheritance, succession and retirement. Focusing on the process of succession, it briefly summarises some of the main similarities and differences in current practice among farm families in the three countries. Having presented a typology of patterns of farming succession based on a review of the literature, the paper goes on to modify this in the light of findings from the more recent surveys.Family Farms, Retirement, Business Succession, Farm Management,
Non-extremal black hole solutions from the c-map
We construct new static, spherically symmetric non-extremal black hole
solutions of four-dimensional supergravity, using a systematic
technique based on dimensional reduction over time (the c-map) and the real
formulation of special geometry. For a certain class of models we actually
obtain the general solution to the full second order equations of motion,
whilst for other classes of models, such as those obtainable by dimensional
reduction from five dimensions, heterotic tree-level models, and type-II
Calabi-Yau compactifications in the large volume limit a partial set of
solutions are found. When considering specifically non-extremal black hole
solutions we find that regularity conditions reduce the number of integration
constants by one half. Such solutions satisfy a unique set of first order
equations, which we identify.
Several models are investigated in detail, including examples of
non-homogeneous spaces such as the quantum deformed model. Though we
focus on static, spherically symmetric solutions of ungauged supergravity, the
method is adaptable to other types of solutions and to gauged supergravity.Comment: 57 pages. Minor changes to the introduction, typos corrected and
references added. Accepted for publication in JHE
Dimensionality and design of isotropic interactions that stabilize honeycomb, square, simple cubic, and diamond lattices
We use inverse methods of statistical mechanics and computer simulations to
investigate whether an isotropic interaction designed to stabilize a given
two-dimensional (2D) lattice will also favor an analogous three-dimensional
(3D) structure, and vice versa. Specifically, we determine the 3D ordered
lattices favored by isotropic potentials optimized to exhibit stable 2D
honeycomb (or square) periodic structures, as well as the 2D ordered structures
favored by isotropic interactions designed to stabilize 3D diamond (or simple
cubic) lattices. We find a remarkable `transferability' of isotropic potentials
designed to stabilize analogous morphologies in 2D and 3D, irrespective of the
exact interaction form, and we discuss the basis of this cross-dimensional
behavior. Our results suggest that the discovery of interactions that drive
assembly into certain 3D periodic structures of interest can be assisted by
less computationally intensive optimizations targeting the analogous 2D
lattices.Comment: 22 pages (preprint version; includes supplementary information), 5
figures, 3 table
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Excess-entropy scaling of dynamics for a confined fluid of dumbbell-shaped particles
We use molecular simulation to study the ability of excess entropy scaling relationships to describe the kinetic properties of a confined molecular system. We examine a model for a confined fluid consisting of dumbbell-shaped molecules that interact with atomistically detailed pore walls via a Lennard-Jones potential. We obtain kinetic, thermodynamic, and structural properties of the system at three wall-fluid interaction strengths and over a temperature range that includes sub-and super-critical conditions. Four dynamic properties are considered: translational and rotational diffusivities, a characteristic relaxation time for rotational motion, and a collective relaxation time stemming from analysis of the coherent intermediate scattering function. We carefully consider the reference state used to define the excess entropy of a confined fluid. Three ideal-gas reference states are considered, with the cases differentiated by the extent to which one-body spatial and orientational correlations are accounted for in the reference state. Our results indicate that a version of the excess entropy that includes information related to the one-body correlations in a confined fluid serves as the best scaling variable for dynamic properties. When adopting such a definition for the reference state, to a very good approximation, bulk and confined data for a specified dynamic property at a given temperature collapse onto a common curve when plotted against the excess entropy.National Science Foundation CBET-0828979Welch Foundation F-1696David and Lucile Packard FoundationChemical Engineerin
Relationship between thermodynamics and dynamics of supercooled liquids
Diffusivity, a measure for how rapidly a fluid self-mixes, shows an intimate,
but seemingly fragmented, connection to thermodynamics. On one hand, the
"configurational" contribution to entropy (related to the number of
mechanically-stable configurations that fluid molecules can adopt) has long
been considered key for predicting supercooled liquid dynamics near the glass
transition. On the other hand, the excess entropy (relative to ideal gas)
provides a robust scaling for the diffusivity of fluids above the freezing
point. Here we provide, to our knowledge, the first evidence that excess
entropy also captures how supercooling a fluid modifies its diffusivity,
suggesting that dynamics, from ideal gas to glass, is related to a single,
standard thermodynamic quantity.Comment: to appear in Journal of Chemical Physic
Pathophysiological role of extrasynaptic GABAA receptors in typical absence epilepsy
GABA is the principal inhibitory neurotransmitter in the mammalian CNS. It acts via two classes of receptors, the GABAA, a ligand gated ion channel (ionotropic receptor) and the metabotropic G-protein coupled GABAB receptor. While synaptic GABAA receptors underlie classical âphasicâ GABAA receptor-mediated inhibition, extrasynaptic GABAA receptors (eGABAAR) mediate a new form of inhibition, termed âtonicâ GABAA inhibition. The subunit composition of eGABAARs differs from those present at the synapse, resulting in pharmacologically and functionally distinct properties. In this mini-review the findings presented at the 2nd Neuroscience Day meeting held last July in Malta will be summarised. Particular emphasis will be given to the important pathophysiological role of eGABAAR within thalamocortical circuits as a major player in nonconvulsive absence epilepsy. The new findings presented at the conference suggest that enhanced tonic inhibition is a common cause of seizures in several animal models of absence epilepsy and may provide new targets for therapeutic intervention.peer-reviewe
Quantification of Order in the Lennard-Jones System
We conduct a numerical investigation of structural order in the shifted-force
Lennard-Jones system by calculating metrics of translational and
bond-orientational order along various paths in the phase diagram covering
equilibrium solid, liquid, and vapor states. A series of non-equilibrium
configurations generated through isochoric quenches, isothermal compressions,
and energy minimizations are also considered. Simulation results are analyzed
using an ordering map representation [Torquato et al., Phys. Rev. Lett. 84,
2064 (2000); Truskett et al., Phys. Rev. E 62, 993 (2000)] that assigns to both
equilibrium and non-equilibrium states coordinates in an order metric plane.
Our results show that bond-orientational order and translational order are not
independent for simple spherically symmetric systems at equilibrium. We also
demonstrate quantitatively that the Lennard-Jones and hard sphere systems
sample the same configuration space at supercritical densities. Finally, we
relate the structural order found in fast-quenched and minimum-energy
configurations (inherent structures).Comment: 35 pages, 8 figure
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