534 research outputs found
The radical left's turn towards civil society in Greece: One strategy, two paths
The Communist Party of Greece (KKE) and the Coalition of the Radical Left (SYRIZA) made remarkable ‘turns towards civil society’ over the last decade. It is argued that this was primarily a response aimed at strengthening their social legitimacy, which had reached its lowest point in the early 1990s. Differences in the way the two parties attempted to stabilise and engage their membership and re-establish links to trade unions and new social movements can be attributed to their distinct ideological and organisational legacies. Despite those differences, their respective linkage strategies were both successful until the game-changing 2012 Greek national elections, which brought about the remarkable rise of SYRIZA and the electoral demise of the KKE
Takayasu arteritis in childhood: retrospective experience from a tertiary referral centre in the United Kingdom.
Takayasu arteritis (TA) is an idiopathic large-vessel vasculitis affecting the aorta and its major branches. Although the disease rarely affects children, it does occur, even in infants. The objective of this study was to evaluate the clinical features, disease activity, treatment and outcome of childhood TA in a tertiary UK centre
Symplectic quaternion scheme for biophysical molecular dynamics
Massively parallel biophysical molecular dynamics simulations, coupled with efficient methods, promise to open biologically significant time scales for study. In order to promote efficient fine-grained parallel algorithms with low communication overhead, the fast degrees of freedom in these complex systems can be divided into sets of rigid bodies. Here, a novel Hamiltonian form of a minimal, nonsingular representation of rigid body rotations, the unit quaternion, is derived, and a corresponding reversible, symplectic integrator is presented. The novel technique performs very well on both model and biophysical problems in accord with a formal theoretical analysis given within, which gives an explicit condition for an integrator to possess a conserved quantity, an explicit expression for the conserved quantity of a symplectic integrator, the latter following and in accord with Calvo and Sanz-Sarna, Numerical Hamiltonian Problems (1994), and extension of the explicit expression to general systems with a flat phase space
Magnetoinductive breathers in magnetic metamaterials
The existence and stability of discrete breathers (DBs) in one-dimensional
and two-dimensional magnetic metamaterials (MMs), which consist of periodic
arrangem ents (arrays) of split-ring resonators (SRRs), is investigated
numerically. We consider different configurations of the SRR arrays, which are
related to the relative orientation of the SRRs in the MM, both in one and two
spatial dimensions. In the latter case we also consider anisotropic MMs. Using
standard numerical methods we construct several types of linearly stable
breather excitations both in Hamiltonian and dissipative MMs (dissipative
breathers). The study of stability in both cases is performed using standard
Floquet analysi s. In both cases we found that the increase of dimensionality
from one to two spatial dimensions does not destroy the DBs, which may also
exist in the case of moderate anisotropy (in two dimensions). In dissipative
MMs, the dynamics is governed by a power balance between the mainly Ohmic
dissipation and driving by an alternating magnetic field. In that case it is
demonstrated that DB excitation locally alters the magnetic response of MMs
from paramagnetic to diamagnetic. Moreover, when the frequency of the applied
field approaches the SRR resonance frequency, the magnetic response of the MM
in the region of the DB excitation may even become negative (extreme
diamagnetic).Comment: 12 pages 15 figure
Granulomatosis with polyangiitis mimicking infective endocarditis in an adolescent male
Granulomatosis with polyangiitis (GPA) is a rare but serious small vessel vasculitis with heterogeneous clinical presentation ranging from mainly localised disease with a chronic course, to a florid, acute small vessel vasculitic form characterised by severe pulmonary haemorrhage and/or rapidly progressive vasculitis or other severe systemic vasculitic manifestations. Cardiac involvement is, however, uncommon in the paediatric population. We report a case of a 16-year-old male who presented with peripheral gangrene and vegetation with unusual location on the supporting apparatus of the tricuspid valve, initially considered to have infective endocarditis but ultimately diagnosed with GPA. We provide an overview of the limited literature relating to cardiac involvement in GPA, and the diagnostic challenge relating to infective endocarditis in this context, especially focusing on the interpretation of the antineutrophil cytoplasmic antibody (ANCA) and the characteristic clinical features to identify in order to promptly recognise GPA, since timely diagnosis and treatment are essential for this potentially life-threatening condition
Nonlinear magnetoinductive transmission lines
Power transmission in one-dimensional nonlinear magnetic metamaterials driven
at one end is investigated numerically and analytically in a wide frequency
range. The nonlinear magnetic metamaterials are composed of varactor-loaded
split-ring resonators which are coupled magnetically through their mutual
inductances, forming thus a magnetoiductive transmission line. In the linear
limit, significant power transmission along the array only appears for
frequencies inside the linear magnetoinductive wave band. We present
analytical, closed form solutions for the magnetoinductive waves transmitting
the power in this regime, and their discrete frequency dispersion. When
nonlinearity is important, more frequency bands with significant power
transmission along the array may appear. In the equivalent circuit picture, the
nonlinear magnetoiductive transmission line driven at one end by a relatively
weak electromotive force, can be modeled by coupled
resistive-inductive-capacitive (RLC) circuits with voltage-dependent
capacitance. Extended numerical simulations reveal that power transmission
along the array is also possible in other than the linear frequency bands,
which are located close to the nonlinear resonances of a single nonlinear RLC
circuit. Moreover, the effectiveness of power transmission for driving
frequencies in the nonlinear bands is comparable to that in the linear band.
Power transmission in the nonlinear bands occurs through the linear modes of
the system, and it is closely related to the instability of a mode that is
localized at the driven site.Comment: 11 pages, 11 figures, submitted to International Journal of
Bifurcation and Chao
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