482 research outputs found
A homomorphism theorem and a Trotter product formula for quantum stochastic flows with unbounded coefficients
We give a new method for proving the homomorphic property of a quantum
stochastic ow satisfying a quantum stochastic differential equation with
unbounded coefficients, under some further hypotheses. As an application, we
prove a Trotter product formula for quantum stochastic ows and obtain quantum
stochastic dilations of a class of quantum dynamical semigroups generalizing
results of [5
Pathways into services for offenders with intellectual disabilities : childhood experience, diagnostic information and offence variables
The patterns and pathways into intellectual disability (ID) offender services were studied through case file review for 477 participants referred in one calendar year to community generic, community forensic, and low, medium, and maximum secure services. Data were gathered on referral source, demographic information, index behavior, prior problem behaviors, diagnostic information, and abuse or deprivation. Community referrers tended to refer to community services and secure service referrers to secure services. Physical and verbal violence were the most frequent index behaviors, whereas contact sexual offenses were more prominent in maximum security. Age at first incident varied with security, with the youngest in maximum secure services. Attention-deficit/hyperactivity disorder or conduct disorder was the most frequently recorded diagnosis, and severe deprivation was the most frequent adverse developmental experience. Fire starting, theft, and road traffic offenses did not feature prominently. Generic community services accepted a number of referrals with forensic-type behavior and had higher proportions of both women and people with moderate or severe ID
Evaluation of the influence of electric nets on the behaviour of oviposition site seeking Anopheles gambaie s.s
Background: Electric nets (e-nets) are used to analyse the flight behaviour of insects and have been used extensively to study the host-oriented flight of tsetse flies. Recently we adapted this tool to analyse the oviposition behaviour of gravid malaria vectors, Anopheles gambiae s.s., orienting towards aquatic habitats and traps by surrounding an artificial pond with e-nets and collecting electrocuted mosquitoes on sticky boards on the ground next to the nets. Here we study whether e-nets themselves affect the responses of gravid An. gambiae s.s.. Methods: Dual-choice experiments were carried out in 80 m2 screened semi-field systems where 200 gravid An. gambiae s.s. were released each night for 12 nights per experiment. The numbers of mosquito landing on or approaching an oviposition site were studied by adding detergent to the water in an artificial pond or surrounding the pond with a square of e-nets. We also assessed whether the supporting framework of the nets or the sticky boards used to retain electrocuted mosquitoes influenced the catch. Results: Two similar detergent treated ponds presented in choice tests caught an equal proportion of the mosquitoes released, whereas a pond surrounded by e-nets caught a higher proportion than an open pond (odds ratio (OR) 1.7, 95% confidence interval (CI) 1.1 - 2.7; p < 0.017). The separate evaluation of the impact of the square of electric nets and the yellow boards on the approach of gravid females towards a pond suggests that the tower-like construction of the square of electric nets did not restrict the approach of females but the yellow sticky boards on the ground attract gravid females to a source of water (OR 2.7 95% CI 1.7 – 4.3; p < 0.001). Conclusion: The trapping efficiency of the electric nets is increased when large yellow sticky boards are placed on the ground next to the e-nets to collect electrocuted mosquitoes, possibly because of increased visual contrast to the aquatic habitat. It is therefore important when comparing two treatments that the same trapping device is used in both. The importance of contrast around artificial habitats might be exploited to improve collections of An. gambiae s.s. in gravid traps
High-temperature weak ferromagnetism on the verge of a metallic state: Impact of dilute Sr-doping on BaIrO3
The 5d-electron based BaIrO3 is a nonmetallic weak ferromagnet with a Curie
temperature at Tc=175 K. Its largely extended orbitals generate strong
electron-lattice coupling, and magnetism and electronic structure are thus
critically linked to the lattice degree of freedom. Here we report results of
our transport and magnetic study on slightly Sr doped BaIrO3. It is found that
dilute Sr-doping drastically suppresses Tc, and instantaneously leads to a
nonmetal-metal transition at high temperatures. All results highlight the
instability of the ground state and the subtle relation between magnetic
ordering and electron mobility. It is clear that BaIrO3 along with very few
other systems represents a class of materials where the magnetic and transport
properties can effectively be tuned by slight alterations in lattice
parameters
Scalar conservation laws with nonconstant coefficients with application to particle size segregation in granular flow
Granular materials will segregate by particle size when subjected to shear,
as occurs, for example, in avalanches. The evolution of a bidisperse mixture of
particles can be modeled by a nonlinear first order partial differential
equation, provided the shear (or velocity) is a known function of position.
While avalanche-driven shear is approximately uniform in depth, boundary-driven
shear typically creates a shear band with a nonlinear velocity profile. In this
paper, we measure a velocity profile from experimental data and solve initial
value problems that mimic the segregation observed in the experiment, thereby
verifying the value of the continuum model. To simplify the analysis, we
consider only one-dimensional configurations, in which a layer of small
particles is placed above a layer of large particles within an annular shear
cell and is sheared for arbitrarily long times. We fit the measured velocity
profile to both an exponential function of depth and a piecewise linear
function which separates the shear band from the rest of the material. Each
solution of the initial value problem is non-standard, involving curved
characteristics in the exponential case, and a material interface with a jump
in characteristic speed in the piecewise linear case
Attention mechanisms in the CHREST cognitive architecture
In this paper, we describe the attention mechanisms in CHREST, a computational architecture of human visual expertise. CHREST organises information acquired by direct experience from the world in the form of chunks. These chunks are searched for, and verified, by a unique set of heuristics, comprising the attention mechanism. We explain how the attention mechanism combines bottom-up and top-down heuristics from internal and external sources of information. We describe some experimental evidence demonstrating the correspondence of CHREST’s perceptual mechanisms with those of human subjects. Finally, we discuss how visual attention can play an important role in actions carried out by human experts in domains such as chess
The European Union, borders and conflict transformation: the case of Cyprus
Much of the existing literature on the European Union (EU), conflict transformation and border dynamics has been premised on the assumption that the nature of the border determines EU intervention and the consequences that flow from this in terms of EU impact. The article aims to transcend this literature through assessing how domestic interpretations influence EU border transformation in conflict situations, taking Cyprus as a case study. Moreover, the objective is to fuse the literature on EU bordering impact and perceptions of the EU’s normative projection in conflict resolution. Pursuing this line of inquiry is an attempt to depart from the notion of borders being constructed solely by unidirectional EU logics of engagement or bordering practices to a conceptualization of the border as co-constituted space, where the interpretations of the EU’s normative projections by conflict parties, and the strategies that they pursue, can determine the relative openness of the EU border
Simulation of dimensionality effects in thermal transport
The discovery of nanostructures and the development of growth and fabrication
techniques of one- and two-dimensional materials provide the possibility to
probe experimentally heat transport in low-dimensional systems. Nevertheless
measuring the thermal conductivity of these systems is extremely challenging
and subject to large uncertainties, thus hindering the chance for a direct
comparison between experiments and statistical physics models. Atomistic
simulations of realistic nanostructures provide the ideal bridge between
abstract models and experiments. After briefly introducing the state of the art
of heat transport measurement in nanostructures, and numerical techniques to
simulate realistic systems at atomistic level, we review the contribution of
lattice dynamics and molecular dynamics simulation to understanding nanoscale
thermal transport in systems with reduced dimensionality. We focus on the
effect of dimensionality in determining the phononic properties of carbon and
semiconducting nanostructures, specifically considering the cases of carbon
nanotubes, graphene and of silicon nanowires and ultra-thin membranes,
underlying analogies and differences with abstract lattice models.Comment: 30 pages, 21 figures. Review paper, to appear in the Springer Lecture
Notes in Physics volume "Thermal transport in low dimensions: from
statistical physics to nanoscale heat transfer" (S. Lepri ed.
Effectiveness of recovered magnesium phosphates as fertilizers in neutral and slightly alkaline soils
Magnesium phosphates such as struvite (MgNH4PO4 · 6H2O) can be recovered from municipal, industrial, and agricultural
wastewaters. However, limited information is available on the beneficial reuse of these recovered products; research has focused
on low pH soils. Th is study determined whether recovered struvite and dittmarite (MgNH4PO4 · H2O) were effective P fertilizers
in neutral to slightly alkaline soils. In addition to commercially available triple superphosphate (TSP) and certified organic
rock phosphate (RP), recovered struvite, dittmarite, and a heterogeneous recovered phosphate were evaluated in a laboratory
dissolution study and as fertilizers for spring wheat (Triticum aestivum L.) in a greenhouse study. Struvite and dittmarite were
much more soluble than RP, but less soluble than TSP. Laboratory dissolution kinetics were fast, with most materials nearing
equilibrium within 7 to 14 d. At a soil pH of 6.5, both dittmarite and struvite increased the average plant P concentration over the
control. Struvite and dittmarite performance was similar to TSP. There were no significant differences in plant dry matter (DM)
production or total P uptake at pH 6.5. In the limed soil (pH 7.6), many treatments had plant P concentrations significantly lower
than the control, but most fertilizers increased DM production over the control; all fertilizers generally performed similarly to
one another. These findings support previous work showing recovered Mg phosphates to be effective in acidic soils, and provide
evidence that they are also effective in slightly alkaline soils. Recovered Mg phosphates could become a useful alternative for P
fertilization in arid and semiarid environments
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