Dissipative breathers in rf SQUID metamaterials

The existence and stability of dissipative breathers in rf SQUID (Superconducting Quantum Interference Device) arrays is investigated numerically. In such arrays, the nonlinearity which is intrinsic to each SQUID, along with the weak magnetic coupling of each SQUID to its nearest neighbors, result in the formation of discrete breathers. We analyze several discrete breather excitations in rf SQUID arrays driven by alternating flux sources in the presence of losses. The delicate balance between internal power losses and input power, results in the formation of dissipative discrete breather (DDB) structures up to relatively large coupling parameters. It is shown that DDBs may locally alter the magnetic response of an rf SQUID array from paramagnetic to diamagnetic or vice versa.Comment: 5 pages, 4 figure

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

Definable group extensions in semi-bounded o-minimal structures

In this note we show: Let ℛ = 〈 R, <, +, 0,...〉 be a semi-bounded (respectively, linear) o-minimal expansion of an ordered group, and G a group definable in R of linear dimension m ([2]). Then G is a definable extension of a bounded (respectively, definably compact) definable group B by 〈 Rm, +〉.FCT Financiamento Base 2008 - USFL/1/209; FCT grant SFRH/BPD/35000/200

The lived experience of juvenile idiopathic arthritis in young people receiving etanercept

BACKGROUND: This study explores young people's daily experiences of living with Juvenile Idiopathic Arthritis (JIA) and their thoughts, beliefs and feelings related to the biological drug Etanercept, prescribed as part of their treatment. METHODS: An Interpretive Phenomenological approach was used to allow in-depth examinations of the young people's personal accounts of their lived experiences. Data were obtained from 6 young people between the ages of 10-13 years, from one tertiary institution's Paediatric Rheumatology department using audio-taped open-ended interviews. RESULTS: The transcripts yielded seven thousand words of data and two hundred significant statements, which were reduced to five themes; 1) Who understands me, 2) Medicines and injections, 3) Challenges of schooling and friendships, 4) Being different, and 5) Exclusion from sports. There were marked similarities between the young people's statements; however, there were also some striking differences. The theme 'Who understands me' yielded the biggest section of data, but also produced the biggest disparity between the young people. Two patients were very clear that they thought everyone 'understands', whilst two other patients held the belief that 'no one understood'. This paper explores these statements in further detail. CONCLUSIONS: The findings from this study can give healthcare professionals novel insight into the likely reactions to treatment for JIA and, through this, enable them to offer improved support, education and early intervention before these issues become a concern. This study also provides insight into the emotional resilience of young people with JIA

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