1,059 research outputs found
The mechanisms of pedestrian slip on flooring contaminated with solid particles
Statistics by the UK Health and Safety Executive (HSE) suggest that slips, trips and falls account for up to one in three major workplace accidents. The vast majority of these accidents are the result of contaminant (fluid or solid) within the shoe-floor contact. Though the lubrication mechanisms for liquid contaminants within the contact are well understood, the same cannot be said for particulate contaminants. This paper considers the key parameters controlling friction in a shoe-floor contact contaminated with various particles of different diameters and shape factors and floors with different roughness values (Rz). Experiments were conducted using a Stanley Pendulum Tester, which is the floor friction tester recommended by the HSE. Results suggest that the adhesive friction is significantly affected by particulate contaminants, while the hysteretic component is not. Three lubrication mechanisms identified as sliding, shearing and rolling have been observed depending on floor roughness, particle size and shape factor and have been plotted in a simple map to predict behaviour
Independence, emancipation and establishment:a critical exploration of the impact of the monastic vision of Downside Abbey (1880-1900)
A preliminary assessment of the radiological impact of the Chernobyl reactor accident on the population of the European Community
On unbounded bodies with finite mass: asymptotic behaviour
There is introduced a class of barotropic equations of state (EOS) which
become polytropic of index at low pressure. One then studies
asymptotically flat solutions of the static Einstein equations coupled to
perfect fluids having such an EOS. It is shown that such solutions, in the same
manner as the vacuum ones, are conformally smooth or analytic at infinity, when
the EOS is smooth or analytic, respectively.Comment: 6 page
Abelian gauge theories on compact manifolds and the Gribov ambiguity
We study the quantization of abelian gauge theories of principal torus
bundles over compact manifolds with and without boundary. It is shown that
these gauge theories suffer from a Gribov ambiguity originating in the
non-triviality of the bundle of connections whose geometrical structure will be
analyzed in detail. Motivated by the stochastic quantization approach we
propose a modified functional integral measure on the space of connections that
takes the Gribov problem into account. This functional integral measure is used
to calculate the partition function, the Greens functions and the field
strength correlating functions in any dimension using the fact that the space
of inequivalent connections itself admits the structure of a bundle over a
finite dimensional torus. The Greens functions are shown to be affected by the
non-trivial topology, giving rise to non-vanishing vacuum expectation values
for the gauge fields.Comment: 33 page
General existence proof for rest frame systems in asymptotically flat space-time
We report a new result on the nice section construction used in the
definition of rest frame systems in general relativity. This construction is
needed in the study of non trivial gravitational radiating systems. We prove
existence, regularity and non-self-crossing property of solutions of the nice
section equation for general asymptotically flat space times. This proves a
conjecture enunciated in a previous work.Comment: 14 pages, no figures, LaTeX 2
Analytic structure of solutions to multiconfiguration equations
We study the regularity at the positions of the (fixed) nuclei of solutions
to (non-relativistic) multiconfiguration equations (including Hartree--Fock) of
Coulomb systems. We prove the following: Let {phi_1,...,phi_M} be any solution
to the rank--M multiconfiguration equations for a molecule with L fixed nuclei
at R_1,...,R_L in R^3. Then, for any j in {1,...,M} and k in {1,...,L}, there
exists a neighbourhood U_{j,k} in R^3 of R_k, and functions phi^{(1)}_{j,k},
phi^{(2)}_{j,k}, real analytic in U_{j,k}, such that phi_j(x) =
phi^{(1)}_{j,k}(x) + |x - R_k| phi^{(2)}_{j,k}(x), x in U_{j,k} A similar
result holds for the corresponding electron density. The proof uses the
Kustaanheimo--Stiefel transformation, as applied earlier by the authors to the
study of the eigenfunctions of the Schr"odinger operator of atoms and molecules
near two-particle coalescence points.Comment: 15 page
Respiratory Insufficiency Correlated Strongly with Mortality of Rodents Infected with West Nile Virus
West Nile virus (WNV) disease can be fatal for high-risk patients. Since WNV or its antigens have been identified in multiple anatomical locations of the central nervous system of persons or rodent models, one cannot know where to investigate the actual mechanism of mortality without careful studies in animal models. In this study, depressed respiratory functions measured by plethysmography correlated strongly with mortality. This respiratory distress, as well as reduced oxygen saturation, occurred beginning as early as 4 days before mortality. Affected medullary respiratory control cells may have contributed to the animals' respiratory insufficiency, because WNV antigen staining was present in neurons located in the ventrolateral medulla. Starvation or dehydration would be irrelevant in people, but could cause death in rodents due to lethargy or loss of appetite. Animal experiments were performed to exclude this possibility. Plasma ketones were increased in moribund infected hamsters, but late-stage starvation markers were not apparent. Moreover, daily subcutaneous administration of 5% dextrose in physiological saline solution did not improve survival or other disease signs. Therefore, infected hamsters did not die from starvation or dehydration. No cerebral edema was apparent in WNV- or sham-infected hamsters as determined by comparing wet-to-total weight ratios of brains, or by evaluating blood-brain-barrier permeability using Evans blue dye penetration into brains. Limited vasculitis was present in the right atrium of the heart of infected hamsters, but abnormal electrocardiograms for several days leading up to mortality did not occur. Since respiratory insufficiency was strongly correlated with mortality more than any other pathological parameter, it is the likely cause of death in rodents. These animal data and a poor prognosis for persons with respiratory insufficiency support the hypothesis that neurological lesions affecting respiratory function may be the primary cause of human WNV-induced death
A note on boundedness of operators in Grand Grand Morrey spaces
In this note we introduce grand grand Morrey spaces, in the spirit of the
grand Lebesgue spaces. We prove a kind of \textit{reduction lemma} which is
applicable to a variety of operators to reduce their boundedness in grand grand
Morrey spaces to the corresponding boundedness in Morrey spaces. As a result of
this application, we obtain the boundedness of the Hardy-Littlewood maximal
operator and Calder\'on-Zygmund operators in the framework of grand grand
Morrey spaces.Comment: 8 page
Construction of -strong Feller Processes via Dirichlet Forms and Applications to Elliptic Diffusions
We provide a general construction scheme for -strong Feller
processes on locally compact separable metric spaces. Starting from a regular
Dirichlet form and specified regularity assumptions, we construct an associated
semigroup and resolvents of kernels having the -strong Feller
property. They allow us to construct a process which solves the corresponding
martingale problem for all starting points from a known set, namely the set
where the regularity assumptions hold. We apply this result to construct
elliptic diffusions having locally Lipschitz matrix coefficients and singular
drifts on general open sets with absorption at the boundary. In this
application elliptic regularity results imply the desired regularity
assumptions
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