1,681 research outputs found
On the path structure of a semimartingale arising from monotone probability theory
Let X be the unique normal martingale such that X_0 = 0 and d[X]_t = (1 - t - X_{t-}) dX_t + dt and let Y_t := X_t + t for all t >= 0; the semimartingale Y arises in quantum probability, where it is the monotone-independent analogue of the Poisson process. The trajectories of Y are examined and various probabilistic properties are derived; in particular, the level set {t >= 0 : Y_t = 1} is shown to be non-empty, compact, perfect and of zero Lebesgue measure. The local times of Y are found to be trivial except for that at level 1; consequently, the jumps of Y are not locally summable
Wheat glutenin subunits and dough elasticity: findings of the EUROWHEAT project
Detailed studies of wheat glutenin subunits have provided novel details of their molecular structures and interactions which allow the development of a model to explain their role in determining the visco-elastic properties of gluten and dough. The construction and analysis of near-isogenic and transgenic lines expressing novel subunit combinations or increased amounts of specific subunits allows differences in gluten properties to be related to the structures and properties of individual subunits, with potential benefits for the production of cultivars with improved properties for food processing or novel end user
International workshop on Time-Variable Phenomena in the Jovian System
Many of the scientifically interesting phenomena that occur in the Jovian system are strongly time variable. Some are episodic (e.g., Io volcanism); some are periodic (wave transport in Jupiters atmosphere); and some are exceedingly complex (magnetosphere - Io - Torus-Auroral interactions) and possibly unstable. To investigate this class of phenomena utilizing Voyager data and, in the future, Galileo results, a coherent program of ground based and earth-orbital observations, and of theory that spans the time between the missions, is required. To stimulate and help define the basis of such a scientific program researchers organized an International Workshop on the subject with the intent of publishing the proceedings which would represent the state of knowledge in 1987
Quantum Feynman-Kac perturbations
We develop fully noncommutative Feynman-Kac formulae by employing quantum
stochastic processes. To this end we establish some theory for perturbing
quantum stochastic flows on von Neumann algebras by multiplier cocycles.
Multiplier cocycles are constructed via quantum stochastic differential
equations whose coefficients are driven by the flow. The resulting class of
cocycles is characterised under alternative assumptions of separability or
Markov regularity. Our results generalise those obtained using classical
Brownian motion on the one hand, and results for unitarily implemented flows on
the other.Comment: 27 pages. Minor corrections to version 2. To appear in the Journal of
the London Mathematical Societ
A matrix formulation of quantum stochastic calculus
We develop the theory of chaos spaces and chaos matrices. A chaos space is a Hilbert space with a fixed, countably-infinite, direct-sum decomposition. A chaos matrix between two chaos spaces is a doubly-infinite matrix of bounded operators which respects this decomposition. We study operators represented by such matrices, particularly with respect to self-adjointness.
This theory is used to re-formulate the quantum stochastic calculus of Hudson and Parthasarathy. Integrals of chaos-matrix processes are defined using the Hitsuda-Skorokhod integral and Malliavin gradient,following Lindsay and Belavkin. A new way of defining adaptedness is developed and the consequent quantum product Ito formula is used to provide a genuine functional Ito formula for polynomials in a large class of unbounded processes, which include the Poisson process and Brownian motion.
A new type of adaptedness, known as -adaptedness, is defined. We show that quantum stochastic integrals of -adapted processes are well-behaved; for instance, bounded processes have bounded integrals. We solve the appropriate modification of the evolution equation of Hudson and Parthasarathy:
where the coefficients are time-dependent, bounded, -adapted processes acting on the whole Fock space. We show that the usual conditions on the coefficients, viz.
(E,F,G,H)=(W-I,L,-WL^{*},iK+\mbox{\frac{1}{2}}LL^{*})
where is unitary and self-adjoint, are necessary and
sufficient conditions for the solution to be unitary. This is a very striking result when compared to the adapted case
Wyoming Sage-Grouse Working Groups: Lessons Learned
The greater sage-grouse (Centrocercus urophasianus) has been the subject of multiple status reviews under the Endangered Species Act (ESA). Wyoming accounts for approximately 38% of the range-wide population. Since 2000, 2 statewide and 8 local citizen working groups have been established in Wyoming to developed conservation plans and advise state policy. The first statewide plan for the conservation of sage-grouse was formally adopted in 2003. The statewide plan established local sage-grouse working groups charged with developing and facilitating implementation of local conservation plans. Those 8 plans were completed in 2007 and 2008, and updated in 2014. From 2005-2017, the local working groups allocated nearly $7 million in legislatively appropriated funds to support conservation projects. In 2007, then Wyoming governor Dave Freudenthal appointed a statewide Sage-grouse Implementation Team. The team was statutorily sanctioned by the Wyoming legislature in 2015 and advises the current governor on all matters related to the Wyoming Greater Sage-Grouse Core Area Protection Policy. The Core Area Policy was established by Executive Order and provides mechanisms for limiting human disturbance in the most important sage-grouse habitats. Federal land management agencies have incorporated most aspects of the Core Area Policy into their land use planning decisions. Effectiveness of local and state-wide collaborative conservation has been evaluated through assessments of local working group accomplishments, research on policy effectiveness, sage-grouse population monitoring, and ESA status reviews
A robust spectroscopic method for the determination of protein conformational composition - application to the annealing of silk
The physical and mechanical properties of structural proteins such as silk fibroin can be modified by controlled conformational change, which is regularly monitored by Fourier transform infrared spectroscopy by peak fitting of the amide I band envelope. Although many variables affecting peak shape are well established, there is no fixed methodology to compare and follow secondary structural differences without significant operator input especially where low frequency spectral noise is a problem.
The aim of this contribution is to establish a method for such analyses to be carried at high levels of autonomy to prevent subjective or erroneous fitting. A range of approaches was trialled with optimal peak parameters selected based on overall goodness of fit and reproducibility of fit of replicate sample spectra. The method was successfully tested against reference proteins having contrasting β content and the rationale for parameter selection is presented.
Further, we applied this method to measure the effect of conformational change on the energy of the amide I band of silk fibroin during annealing. Energy changes were ca. 400 kJ mol−1 of fibroin. To confirm that this energy change was a consequence of increased hydrogen bonding we used a Thioflavin T staining method typically used to identify β aggregate type structures in amyloid plaques.
We propose that the approach described herein can aid in the development of silk based materials for biomedical applications where tuning of the physical and mechanical properties of the silk are needed to guarantee optimum activity
Not just for the wealthy: Rethinking farmed fish consumption in the Global South
Aquaculture’s contributions to food security in the Global South are widely misunderstood. Dominant narratives suggest that aquaculture contributes mainly to international trade benefiting richer Northern consumers, or provides for wealthy urban consumers in Southern markets. On the supply side, the literature promotes an idealized vision of ‘small-scale’, low input, semi-subsistence farming as the primary means by which aquaculture can contribute to food security, or emphasizes the role of ‘industrial’ export oriented aquaculture in undermining local food security. In fact, farmed fish is produced predominantly by a ‘missing middle’ segment of commercial and increasingly intensive farms, and overwhelmingly remains in Southern domestic markets for consumption by poor and middle income consumers in both urban and rural areas, making an important but underappreciated contribution to global food security
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