7,405 research outputs found
Non-perturbative renormalization of the KPZ growth dynamics
We introduce a non-perturbative renormalization approach which identifies
stable fixed points in any dimension for the Kardar-Parisi-Zhang dynamics of
rough surfaces. The usual limitations of real space methods to deal with
anisotropic (self-affine) scaling are overcome with an indirect functional
renormalization. The roughness exponent is computed for dimensions
to 8 and it results to be in very good agreement with the available
simulations. No evidence is found for an upper critical dimension. We discuss
how the present approach can be extended to other self-affine problems.Comment: 4 pages, 2 figures. To appear in Phys. Rev. Let
On the interactions between molecules in an off-resonant laser beam:Evaluating the response to energy migration and optically induced pair forces
Electronically excited molecules interact with their neighbors differently from their ground-state counterparts. Any migration of the excitation between molecules can modify intermolecular forces, reflecting changes to a local potential energy landscape. It emerges that throughput off-resonant radiation can also produce significant additional effects. The context for the present analysis of the mechanisms is a range of chemical and physical processes that fundamentally depend on intermolecular interactions resulting from second and fourth-order electric-dipole couplings. The most familiar are static dipole-dipole interactions, resonance energy transfer (both second-order interactions), and dispersion forces (fourth order). For neighboring molecules subjected to off-resonant light, additional forms of intermolecular interaction arise in the fourth order, including radiation-induced energy transfer and optical binding. Here, in a quantum electrodynamical formulation, these phenomena are cast in a unified description that establishes their inter-relationship and connectivity at a fundamental level. Theory is then developed for systems in which the interplay of these forms of interaction can be readily identified and analyzed in terms of dynamical behavior. The results are potentially significant in Förster measurements of conformational change and in the operation of microelectromechanical and nanoelectromechanical devices. © 2009 American Institute of Physics
Tunable coaxial resonators based on silicon optical fibers
Thermal tuning of a coaxial fiber resonator with a silica cladding surrounding an inner silicon core is investigated. By pumping the silicon with below bandgap light, it is possible to redshift the WGM resonances
Re Ass\u27n of Radio & Television Employees and Canadian Broadcasting Corp
Employee Grievance alleging unjust discharge.
Award (in part)
It is widely accepted by labour arbitration boards in Ontario that the onus of proving just cause is on the company in dismissal cases, where the collective agreement contains the usual provision and there is no practice to the contrary clearly established between the parties. See for example Re Int\u27l Ass\u27n of Machinists, Local 749, and Timken Roller Bearing Co. (1952), 4 L.A.C. 1262 (E.W. Cross, C.C.J., chairman); Re United Brewery Workers and Dow Kingsbeer Brewery Ltd. (1958), 8 L.A.C.198 (B. Laskin, chairman), and Re U.E.W., Local 504, and Canadian Westinghouse Co. Ltd. (1966), 17 L.A.C. 427 (E.E. Palmer, chairman). The last of these cases is a discipline case in which Professor Palmer decided that the rule in discharge cases, which puts the onus on the company, should be extended, and cites the decisions of other arbitrators agreeing with him. It is unnecessary for us to deal with this point, but the awards cited by Professor Palmer establish beyond doubt that the normal rule in Ontario is for the company to bear the onus of proving just cause in discharge cases
A numerical study of the development of bulk scale-free structures upon growth of self-affine aggregates
During the last decade, self-affine geometrical properties of many growing
aggregates, originated in a wide variety of processes, have been well
characterized. However, little progress has been achieved in the search of a
unified description of the underlying dynamics. Extensive numerical evidence
has been given showing that the bulk of aggregates formed upon ballistic
aggregation and random deposition with surface relaxation processes can be
broken down into a set of infinite scale invariant structures called "trees".
These two types of aggregates have been selected because it has been
established that they belong to different universality classes: those of
Kardar-Parisi-Zhang and Edward-Wilkinson, respectively. Exponents describing
the spatial and temporal scale invariance of the trees can be related to the
classical exponents describing the self-affine nature of the growing interface.
Furthermore, those exponents allows us to distinguish either the compact or
non-compact nature of the growing trees. Therefore, the measurement of the
statistic of the process of growing trees may become a useful experimental
technique for the evaluation of the self-affine properties of some aggregates.Comment: 19 pages, 5 figures, accepted for publication in Phys.Rev.
A descriptive epidemiological study of mastitis in 12 Irish dairy herds
<p/> <p>Factors relating to the occurrence of mastitis were studied on 12 Irish dairy herds with histories of elevated somatic cell count (SCC) and/or increased incidence of clinical mastitis cases. Milk recording data were analysed, housing conditions and calving areas were examined; dry cow therapy, clinical mastitis records, milking technique and aspects of milking machine function were assessed.</p> <p>Herds with a ratio of less than 110 cubicles per 100 cows were more likely to experience environmental mastitis. Herds with inadequate calving facilities, where cows spent prolonged periods on straw bedding, were likely to acquire environmental mastitis. In the majority of the herds, the selection of dry cow therapy lacked adequate planning. The majority of farmers took no action to reduce pain experienced by cows suffering mastitis. Deficiencies in parlour hygiene were evident in all herds experiencing elevation in SCC.</p
An Exactly Solved Model of Three Dimensional Surface Growth in the Anisotropic KPZ Regime
We generalize the surface growth model of Gates and Westcott to arbitrary
inclination. The exact steady growth velocity is of saddle type with principal
curvatures of opposite sign. According to Wolf this implies logarithmic height
correlations, which we prove by mapping the steady state of the surface to
world lines of free fermions with chiral boundary conditions.Comment: 9 pages, REVTEX, epsf, 3 postscript figures, submitted to J. Stat.
Phys, a wrong character is corrected in eqs. (31) and (32
A molecular theory for two-photon and three-photon fluorescence polarization
In the analysis of molecular structure and local order in heterogeneous samples, multiphoton excitation of fluorescence affords chemically specific information and high-resolution imaging. This report presents the results of an investigation that secures a detailed theoretical representation of the fluorescence polarization produced by one-, two-, and three-photon excitations, with orientational averaging procedures being deployed to deliver the fully disordered limits. The equations determining multiphoton fluorescence response prove to be expressible in a relatively simple, generic form, and graphs exhibit the functional form of the multiphoton fluorescence polarization. Amongst other features, the results lead to the identification of a condition under which the fluorescence produced through the concerted absorption of any number of photons becomes completely unpolarized. It is also shown that the angular variation of fluorescence intensities is reliable indicator of orientational disorder
High dimensional behavior of the Kardar-Parisi-Zhang growth dynamics
We investigate analytically the large dimensional behavior of the
Kardar-Parisi-Zhang (KPZ) dynamics of surface growth using a recently proposed
non-perturbative renormalization for self-affine surface dynamics. Within this
framework, we show that the roughness exponent decays not faster than
for large . This implies the absence of a finite upper
critical dimension.Comment: RevTeX, 4 pages, 2 figures. To appear in Phys. Rev.
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