593 research outputs found
A CRITICAL VIEW OF DIVERSION PROGRAMMES IN CONTEXT OF RESTORATIVE JUSTICE
This article describes the background and purpose of life-skills diversion programmes for young offender and then critically explores to what extent they currently endorse theprinciples of restorative justice to which the new South African child justice system aspires. Since the advent of the life-skills programmes for youths at risk, the child justice system has evolved into a comprehensive piece of legislation called the Child Justice Bill (Bill 49[2002]). Central to this Bill is the promotion of re toralive justice, which seeks to repair damage caused by crime by returning criminal cases to the main players: the victim, the offender and the community. Through a process of negotiation, these players agree on appropriate solutions which include (]) restitution, (2) reconciliation following an acknowledgement of the circumstances around the offence and its impact, and (3) an acceptance of responsibility by the offender leading to reintegration into the community. Diversion options from criminal justice procedures are the key to installing restorative justice for crimes committed by young offenders. To date the most popular form of diversion has been life-skills programmes for youths at risk, but it is not evident to what extent this meets the criteria inherent in the philosophy of restorative justice
Andreev bound states at a cuprate grain boundary junction: A lower bound for the upper critical field
We investigate in-plane quasiparticle tunneling across thin film grain
boundary junctions (GBJs) of the electron-doped cuprate
LaCeCuO in magnetic fields up to T, perpendicular to
the CuO layers. The differential conductance in the superconducting state
shows a zero bias conductance peak (ZBCP) due to zero energy surface Andreev
bound states. With increasing temperature , the ZBCP vanishes at the
critical temperature K if B=0, and at K for B=16 T. As
the ZBCP is related to the macroscopic phase coherence of the superconducting
state, we argue that the disappearance of the ZBCP at a field
must occur below the upper critical field of the superconductor. We
find T which is at least a factor of 2.5 higher than
previous estimates of .Comment: 4 pages, 4 figure
Analogue mouse pointer control via an online steady state visual evoked potential (SSVEP) brain-computer interface
The steady state visual evoked protocol has recently become a popular paradigm in brain–computer interface (BCI) applications. Typically (regardless of function) these applications offer the user a binary selection of targets that perform correspondingly discrete actions. Such discrete control systems are appropriate for applications that are inherently isolated in nature, such as selecting numbers from a keypad to be dialled or letters from an alphabet to be spelled. However motivation exists for users to employ proportional control methods in intrinsically analogue tasks such as the movement of a mouse pointer. This paper introduces an online BCI in which control of a mouse pointer is directly proportional to a user's intent. Performance is measured over a series of pointer movement tasks and compared to the traditional discrete output approach. Analogue control allowed subjects to move the pointer faster to the cued target location compared to discrete output but suffers more undesired movements overall. Best performance is achieved when combining the threshold to movement of traditional discrete techniques with the range of movement offered by proportional control
Extinction of impurity resonances in large-gap regions of inhomogeneous d-wave superconductors
Impurity resonances observed by scanning tunneling spectroscopy in the
superconducting state have been used to deduce properties of the underlying
pure state. Here we study a longstanding puzzle associated with these
measurements, the apparent extinction of these resonances for Ni and Zn
impurities in large-gap regions of the inhomogeneous BSCCO superconductor. We
calculate the effect of order parameter and hopping suppression near the
impurity site, and find that these two effects are sufficient to explain the
missing resonances in the case of Ni. There are several possible scenarios for
the extinction of the Zn resonances, which we discuss in turn; in addition, we
propose measurements which could distinguish among them.Comment: 10 pages, 8 figure
Volovik effect in a highly anisotropic multiband superconductor: experiment and theory
We present measurements of the specific heat coefficient \gamma(= C/T) in the
low temperature limit as a function of an applied magnetic field for the
Fe-based superconductor BaFe(AsP). We find both a
linear regime at higher fields and a limiting square root behavior at very
low fields. The crossover from a Volovik-like to a linear field
dependence can be understood from a multiband calculation in the quasiclassical
approximation assuming gaps with different momentum dependence on the hole- and
electron-like Fermi surface sheets.Comment: 11 pages, 8 figures, 1 table, submitted to Phys. Rev.
Superconductivity in striped and multi-Fermi-surface Hubbard models: From the cuprates to the pnictides
Single- and multi-band Hubbard models have been found to describe many of the
complex phenomena that are observed in the cuprate and iron-based
high-temperature superconductors. Simulations of these models therefore provide
an ideal framework to study and understand the superconducting properties of
these systems and the mechanisms responsible for them. Here we review recent
dynamic cluster quantum Monte Carlo simulations of these models, which provide
an unbiased view of the leading correlations in the system. In particular, we
discuss what these simulations tell us about superconductivity in the
homogeneous 2D single-orbital Hubbard model, and how charge stripes affect this
behavior. We then describe recent simulations of a bilayer Hubbard model, which
provides a simple model to study the type and nature of pairing in systems with
multiple Fermi surfaces such as the iron-based superconductors.Comment: Published as part of Superstripes 2011 (Rome) conference proceeding
Semi-Automated Location Planning for Urban Bike-Sharing Systems
Bike-sharing has developed into an established part of many urban transportation systems. However, new bikesharing
systems (BSS) are still built and existing ones are extended. Particularly for large BSS, location planning
is complex since factors determining potential usage are manifold. We propose a semi-automatic approach for
creating or extending real-world sized BSS during general planning. Our approach optimizes locations such that
the number of trips is maximized for a given budget respecting construction as well as operation costs. The
approach consists of four steps: (1) collecting and preprocessing required data, (2) estimating a demand model,
(3) calculating optimized locations considering estimated redistribution costs, and (4) presenting the solution to
the planner in a visualization and planning front end. The full approach was implemented and evaluated positively
with BSS and planning experts
Sensitivity of the superconducting state and magnetic susceptibility to key aspects of electronic structure in ferropnictides
Experiments on the iron-pnictide superconductors appear to show some
materials where the ground state is fully gapped, and others where low-energy
excitations dominate, possibly indicative of gap nodes. Within the framework of
a 5-orbital spin fluctuation theory for these systems, we discuss how changes
in the doping, the electronic structure or interaction parameters can tune the
system from a fully gapped to nodal sign-changing gap with s-wave ()
symmetry (). In particular we focus on the role of the hole pocket at
the point of the unfolded Brillouin zone identified as crucial to
the pairing by Kuroki {\it et al.}, and show that its presence leads to
additional nesting of hole and electron pockets which stabilizes the isotropic
state. The pocket's contribution to the pairing can be tuned by doping,
surface effects, and by changes in interaction parameters, which we examine.
Analytic expressions for orbital pairing vertices calculated within the RPA
fluctuation exchange approximation allow us to draw connections between aspects
of electronic structure, interaction parameters, and the form of the
superconducting gap
Single vortex structure in two models of iron pnictide superconductivity
The structure of a single vortex in a FeAs superconductor is studied in the
framework of two formulations of superconductivity for the recently proposed
sign-reversed wave () scenario: {\it (i)} a continuum model taking
into account the existence of an electron and a hole band with a repulsive
local interaction between the two; {\it (ii)} a lattice tight-binding model
with two orbitals per unit cell and a next-nearest-neighbour attractive
interaction. In the first model, the local density of states (LDOS) at the
vortex centre, as a function of energy, exhibits a peak at the Fermi level,
while in the second model such LDOS peak is deviated from the Fermi level and
its energy depends on band filling. An impurity located outside the vortex core
has little effect on the LDOS peak, but an impurity close to the vortex core
can almost suppress it and modify its position.Comment: 17 pages, 15 figures. Accepted for publication in New Journal of
Physic
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