17,417 research outputs found
Gambling in Great Britain:a response to Rogers
A recent issue of Practice: Social Work in Action featured a paper by Rogers that examined whether the issue of problem gambling was a suitable case for social work. Rogers’ overview was (in various places) out of date, highly selective, contradictory, presented unsupported claims and somewhat misleading. Rogers’ paper is to be commended for putting the issue of problem gambling on the social work agenda. However, social workers need up-to-date information and contextually situated information if they are to make informed decisions in helping problem gamblers
Experimental analysis of multistatic multiband radar signatures of wind turbines
This study presents the analysis of recent experimental data acquired using two radar systems at S-band and X-band to measure simultaneous monostatic and bistatic signatures of operational wind turbines near Shrivenham, UK. Bistatic and multistatic radars are a potential approach to mitigate the adverse effects of wind farm clutter on the performance of radar systems, which is a well-known problem for air traffic control and air defence radar. This analysis compares the simultaneous monostatic and bistatic micro-Doppler signatures of two operational turbines and investigates the key differences at bistatic angles up to 23°. The variations of the signature with different polarisations, namely vertical transmitted and vertical received and horizontal transmitted and horizontal received, are also discussed
Image charge effects in single-molecule junctions: Breaking of symmetries and negative differential resistance in a benzene transistor
Both experiments and theoretical studies have demonstrated that the
interaction between the current carrying electrons and the induced polarization
charge in single-molecule junctions leads to a strong renormalization of
molecular charging energies. However, the effect on electronic excitations and
molecular symmetries remain unclear. Using a theoretical framework developed
for semiconductor nanostructure based single-electron transistors (SETs), we
demonstrate that the image charge interaction breaks the molecular symmetries
in a benzene based single-molecule transistor operating in the Coulomb blockade
regime. This results in the appearance of a so-called blocking state, which
gives rise to negative differential resistance (NDR). We show that the
appearance of NDR and its magnitude in the symmetry-broken benzene SET depends
in a complicated way on the interplay between the many-body matrix elements,
the lead tunnel coupling asymmetry, and the bias polarity. In particular, the
current reducing property of the blocking state causing the NDR, is shown to
vanish under strongly asymmetric tunnel couplings, when the molecule is coupled
stronger to the drain electrode. The calculated IV characteristic may serve as
an indicator for image charge broken molecular symmetries in experimental
situations.Comment: Accepted version (Phys. Rev. B), 16 pages, 8 figure
Consistent Quantum Counterfactuals
An analysis using classical stochastic processes is used to construct a
consistent system of quantum counterfactual reasoning. When applied to a
counterfactual version of Hardy's paradox, it shows that the probabilistic
character of quantum reasoning together with the ``one framework'' rule
prevents a logical contradiction, and there is no evidence for any mysterious
nonlocal influences. Counterfactual reasoning can support a realistic
interpretation of standard quantum theory (measurements reveal what is actually
there) under appropriate circumstances.Comment: Minor modifications to make it agree with published version. Latex 8
pages, 2 figure
Social interactions in massively multiplayer online role-playing gamers
To date, most research into massively multiplayer online role-playing games (MMORPGs) has examined the demographics of play. This study explored the social interactions that occur both within and outside of MMORPGs. The sample consisted of 912 self-selected MMORPG players from 45 countries. MMORPGs were found to be highly socially interactive environments providing the opportunity to create strong friendships and emotional relationships. The study demonstrated that the social interactions in online gaming form a considerable element in the enjoyment of playing. The study showed MMORPGs can be extremely social games, with high percentages of gamers making life-long friends and partners. It was concluded that virtual gaming may allow players to express themselves in ways they may not feel comfortable doing in real life because of their appearance, gender, sexuality, and/or age. MMORPGs also offer a place where teamwork, encouragement, and fun can be experienced
General pure multipartite entangled states and the Segre variety
In this paper, we construct a measure of entanglement by generalizing the
quadric polynomial of the Segre variety for general multipartite states. We
give explicit expressions for general pure three-partite and four-partite
states. Moreover, we will discuss and compare this measure of entanglement with
the generalized concurrence.Comment: 5 page
Noncommutative geometrical structures of entangled quantum states
We study the noncommutative geometrical structures of quantum entangled
states. We show that the space of a pure entangled state is a noncommutative
space. In particular we show that by rewritten the conifold or the Segre
variety we can get a -deformed relation in noncommutative geometry. We
generalized our construction into a multi-qubit state. We also in detail
discuss the noncommutative geometrical structure of a three-qubit state.Comment: 7 page
Plant root proliferation in nitrogen-rich patches confers competitive advantage
Plants respond to environmental heterogeneity, particularly below ground, where spectacular root proliferations in nutrient-rich patches may occur. Such 'foraging' responses apparently maximize nutrient uptake and are now prominent in plant ecological theory. Proliferations in nitrogen-rich patches are difficult to explain adaptively, however. The high mobility of soil nitrate should limit the contribution of proliferation to N capture. Many experiments on isolated plants show only a weak relation between proliferation and N uptake. We show that N capture is associated strongly with proliferation during interspecific competition for finite, locally available, mixed N sources, precisely the conditions under which N becomes available to plants on generally infertile soils. This explains why N-induced root proliferation is an important resource-capture mechanism in N-limited plant communities and suggests that increasing proliferation by crop breeding or genetic manipulation will have a limited impact on N capture by well-fertilized monocultures
An experimental and theoretical investigation of particle–wall impacts in a T-junction
Understanding the behaviour of particles entrained in a fluid flow upon changes in flow direction is crucial in problems where particle inertia is important, such as the erosion process in pipe bends.We present results on the impact of particles in a T-shaped channel in the laminar-turbulent transitional regime. The impacting event for a given system is described in terms of the Reynolds number and the particle Stokes number. Experimental results for the impact are compared with the trajectories predicted by theoretical particle tracing models for a range of configurations to determine the role of the viscous boundary layer in retarding the particles and reducing the rate of collision with the substrate. In particular a 2D model based on a stagnation point flow is used together with 3D numerical simulations. We show how the simple 2D model provides a tractable way of understanding the general collision behaviour, while more advanced 3D simulation can be helpful in understanding the details of the flow
Dynamical approach study of spurious steady-state numerical solutions of nonlinear differential equations. Part 1: The ODE connection and its implications for algorithm development in computational fluid dynamics
Spurious stable as well as unstable steady state numerical solutions, spurious asymptotic numerical solutions of higher period, and even stable chaotic behavior can occur when finite difference methods are used to solve nonlinear differential equations (DE) numerically. The occurrence of spurious asymptotes is independent of whether the DE possesses a unique steady state or has additional periodic solutions and/or exhibits chaotic phenomena. The form of the nonlinear DEs and the type of numerical schemes are the determining factor. In addition, the occurrence of spurious steady states is not restricted to the time steps that are beyond the linearized stability limit of the scheme. In many instances, it can occur below the linearized stability limit. Therefore, it is essential for practitioners in computational sciences to be knowledgeable about the dynamical behavior of finite difference methods for nonlinear scalar DEs before the actual application of these methods to practical computations. It is also important to change the traditional way of thinking and practices when dealing with genuinely nonlinear problems. In the past, spurious asymptotes were observed in numerical computations but tended to be ignored because they all were assumed to lie beyond the linearized stability limits of the time step parameter delta t. As can be seen from the study, bifurcations to and from spurious asymptotic solutions and transitions to computational instability not only are highly scheme dependent and problem dependent, but also initial data and boundary condition dependent, and not limited to time steps that are beyond the linearized stability limit
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