968 research outputs found
Stochastic models (cooperative and non-cooperative) for NMR analysis of the hetero-association of aromatic molecules in aqueous solution
Stochastic cooperative (STOCH-C) and non-cooperative (STOCH-NC) models have been developed for NMR analysis of the hetero-association of aromatic compounds in solution, in order to take into account all physically meaningful association reactions of molecules in which there are no limitations on the lengths of the aggregates and complexes. These algorithmical approaches are compared with previously published basic (BASE) and generalized (GEN) analytical statistical thermodynamical models of hetero-association of biologically active aromatic molecules using the same sets of published NMR data measured under the same solution conditions (0.1 M phosphate buffer, pD = 7.1, T = 298 K). It is shown that, within experimental errors, the BASE analytical model may be used to describe molecular systems characterized by relatively small contributions of hetero-association reactions, whereas the GEN model may be applied to hetero-association reactions of any aromatic compound with different self-association properties. The STOCH-C computational algorithm enabled the effect on hetero-association of the interactions of molecules with different cooperativity parameters of self-association to be estimated for the first time and it is proposed that the algorithm for the stochastic models has great potential for detailed investigation and understanding of the interactions of aromatic molecules in solution
Stochastic Differential Equations Driven by Fractional Brownian Motion and Standard Brownian Motion
We prove an existence and uniqueness theorem for solutions of
multidimensional, time dependent, stochastic differential equations driven
simultaneously by a multidimensional fractional Brownian motion with Hurst
parameter H>1/2 and a multidimensional standard Brownian motion. The proof
relies on some a priori estimates, which are obtained using the methods of
fractional integration, and the classical Ito stochastic calculus. The
existence result is based on the Yamada-Watanabe theorem.Comment: 21 page
The shape and behaviour of a granular bed in a rotating drum using Eulerian flow fields obtained from PEPT
Non-invasive single-particle tracking techniques, such as positron emission particle tracking (PEPT), provide useful information about the behaviour of a representative particle moving in a bulk of similar particles in a rotating drum. The Lagrangian trajectories that they yield can be used to study, for example, particulate diff usion or granular interaction. However, often the Eulerian flow fi elds of the entire granular bed are more useful-- they can be used to study segregation, for instance, or the evolution of the free surface of the bed. In this work, we present a technique for converting Lagrangian trajectories to Eulerian flow fields via a time-weighted residence time distribution (RTD) of the tracked particle. We then perform PEPT experiments on a mono-disperse bed of spherical particles in a cylindrical drum, rotated at various rates, and use the RTD procedure to obtain flow fi elds of the bed. We use these flow fi elds to investigate the e ffect of drum rotational speed on the shape and behaviour of a granular bed in a rotating drum, and the insights gained thereby to defi ne a comprehensive set of surfaces{ such as the bulk free surface{ to divide the bed into regions of distinct granular behaviour. We further defi ne scalar bed features-- such as the centre of circulation of the bed-- that can be used to quantitatively compare the behaviour of granular beds in rotating drums operated under various conditions
Everything you ever wanted to know about sweetpotato: Reaching agents of change ToT manual. 6: Gender and diversity aspects. Monitoring of OFSP dissemination and uptake.
Learning the Smart Way: Lessons Learned by the Reaching Agents of Change Project.
The Reaching Agents of Change (RAC) project was a pilot that advocated for increased investment in orange-fleshed sweetpotato to combat vitamin A deficiency among young children and women of reproductive age. It was implemented by the International Potato Center and Helen Keller International primarily in Nigeria, Mozambique, Tanzania and to a lesser extent in Ghana and Burkina Faso between 2011 and 2014. The project had multiple deliverables in advocacy for raising of new investment, policy change and strengthening of institutional and individual capacities in the project countries. RAC incorporated a systematic and comprehensive results-based monitoring and evaluation system and continuously documented the implementation process over the project period. This booklet shares the learning process that RAC adopted and highlights some useful and replicable lessons learned
The composition of serous fluid after axillary dissection
Objective: To analyse the composition of the serous fluid formed after axillary dissection Design: Descriptive study Setting: University hospital and teaching hospital, The Netherlands Subjects: 16 patients whose axillas were dissected as part of a modified radical mastectomy for stage I or II breast cancer. Main outcome measures: Chemical and cellular composition of axillary drainage fluid on the first, fifth, and tenth postoperative days compared with the same constituents in blood and with reported data on the composition of peripheral lymph. Results and conclusion: On the first postoperative day the drainage fluid contained blood contents and a high concentration of creatine phosphokinase (CPK). After day one it changed to a peripheral lymph-like fluid but containing different cells, more protein, and no fibrinogen, making coagulation impossible. The reduction in the fluid production must be caused by other wound healing processes, such as formation of scars and connective tissue
Entropy and the variational principle for actions of sofic groups
Recently Lewis Bowen introduced a notion of entropy for measure-preserving
actions of a countable sofic group on a standard probability space admitting a
generating partition with finite entropy. By applying an operator algebra
perspective we develop a more general approach to sofic entropy which produces
both measure and topological dynamical invariants, and we establish the
variational principle in this context. In the case of residually finite groups
we use the variational principle to compute the topological entropy of
principal algebraic actions whose defining group ring element is invertible in
the full group C*-algebra.Comment: 44 pages; minor changes; to appear in Invent. Mat
Gaussian multiplicative Chaos for symmetric isotropic matrices
Motivated by isotropic fully developed turbulence, we define a theory of
symmetric matrix valued isotropic Gaussian multiplicative chaos. Our
construction extends the scalar theory developed by J.P. Kahane in 1985
Alkali incorporation into solution processed CIGS precursor layers
Solution based ion-exchange reactions offer a
simple, non-vacuum route for adding Cu into In-
Ga-Se precursor layers as a step in a low-cost
process for the preparation of Cu(In, Ga)Se2
(CIGS) solar cells. The chemically treated
precursor layers may be converted into CIGS
by annealing with Se vapour. Structural and
compositional characterisation has shown that
the converted layers have good composition,
microstructure and crystalline phase content.
Nevertheless, photovoltaic cells processed
from these layers have failed to produce energy
conversion efficiencies greater than ~4% under
standard test conditions. The chemical bath
used for the incorporation of Cu into the
precursor layers includes a complexant for
stability and this complexant contains alkali
atoms, which are known to strongly influence
the properties of CIGS. Low alkali content is
highly desirable in CIGS layers but excessive
inclusion may be detrimental. This paper
reports the results of an investigation into the
potential incorporation of excess alkali atoms
from the solution into the precursor layers.
Whilst no evidence of alkali incorporation is
detected by energy dispersive X-ray analysis,
clear evidence is seen in time-of-flight
secondary ion mass spectrometry
measurements. The implications of this are
discussed in terms of reported effects on
device performance
On finite-difference approximations for normalized Bellman equations
A class of stochastic optimal control problems involving optimal stopping is
considered. Methods of Krylov are adapted to investigate the numerical
solutions of the corresponding normalized Bellman equations and to estimate the
rate of convergence of finite difference approximations for the optimal reward
functions.Comment: 36 pages, ArXiv version updated to the version accepted in Appl.
Math. Opti
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