Hardware Coupled Nonliear Oscillators as a Model of Retina

An electronic circuit consisting of coupled nonlinear oscillators⁴＇⁵ simulates the spatiotemporal processing in retina. Complex behavior recorded in vivo from ganglion cells in the cat retina 6 in response to flickering light spots is matched by setting the coupling parameters in the hardware oscillators. An electronic neuron (c-neuron) is composed of four coupled oscillators: three representing the light driven generator potential of the ganglion cell, the other representing membrane spiking. A 1-D ring of e-neurons reflects the connectivity in the retina: strong neighborhood excitation, and wider inhibition. E-neurons, like retinal ganglion cells, exhibit spontaneous spiking. Driving more than one e-neuron with a sinusoidally modulated input increases regularity in the e-neurons responses, as is found in the retina. We encoded c-neuron activity into single-bit spike trains and found chaotic spontaneous oscillations using close return histograms. The model's behavior gives a new understanding of neurophysiological findings.Whitehall (S93-24); Air Force Office of Scientific Research (F49620-92-J-0499, F49620-92-J-0334); Office of Naval Research (N00014-89-J-1377, N00014-95-I-0409); MIT Undergraduate Research Oppurtunities Progra

Northward field excursions in Saturn’s magnetotail and their relationship to magnetospheric periodicities

We present results from an investigation of Cassini encounters with Saturn’s magnetotail current sheet, using magnetic field and plasma data. In the first of two intervals shown, small periodic changes in the north-south component of the magnetic field are matched by periodic density enhancements associated with the plasma sheet center. In the second interval, a large plasmoid signature is observed set against a background of small-scale current sheet motions. We interpret the quasi-periodic small field deflections and density enhancements as large-scale wave-like motion of the current sheet. We stress that plasmoid signatures are of a clearly different character and occur much less frequently

Bone Health Improvement Protocol

Introduction. Metabolic bone disease is a malady that causessignificant morbidity and mortality to a patient who has sustaineda fragility fracture. There is currently no protocol toprevent secondary fragility fracture at our institution. The objectiveof this study was to create an appropriate protocol forimplementing clinical pathways for physicians to diagnose andtreat osteoporosis and fragility fractures by educating patients. Methods. A multidisciplinary team created an appropriateprotocol that could be implemented in an inpatient setting.A thorough literature review was conducted to evaluatepotential barriers and efficacious methods of protocol design. Results. A bone health improvement protocol was developed.Any patient over the age of 50 who sustains a fracture from lowenergy trauma, such as a fall from standing or less, should beconsidered to place into this protocol. These patients receivededucation on metabolic bone disease, a prescription for highdose vitamin D therapy, and laboratory testing to determinethe etiology of their metabolic bone disease. Continuity of careof these patients with their primary care provider was providedfor further management of their metabolic bone disease andevaluation of their disease after discharged from the hospital. Conclusion. Comprehensive secondary prevention should consistof osteoporosis assessment and treatment together with afall risk assessment. With this protocol, secondary fragility fracturespotentially could be prevented. KS J Med 2017;10(3):62-66

PT Invariant Complex E (8) Root Spaces

We provide a construction procedure for complex root spaces invariant under antilinear transformations, which may be applied to any Coxeter group. The procedure is based on the factorisation of a chosen element of the Coxeter group into two factors. Each of the factors constitutes an involution and may therefore be deformed in an antilinear fashion. Having the importance of the E(8)-Coxeter group in mind, such as underlying a particular perturbation of the Ising model and the fact that for it no solution could be found previously, we exemplify the procedure for this particular case. As a concrete application of this construction we propose new generalisations of Calogero-Moser Sutherland models and affine Toda field theories based on the invariant complex root spaces and deformed complex simple roots, respectively

Developing Community Nursing Practice: Promoting Case Management and Skill Enhancement to Support Shifting the Balance of Care

Five inter-related projects were commissioned by NHS Highland to further knowledge and understanding of key issues that can be used to inform particular aspects of care delivery that supports the community nurse review. The five projects reflect some of the core elements that have been identified to maximise nurses’ contributions in community settings (Scottish Executive 2006a). The projects were designed to provide qualitative evidence of the views of community nurses regarding case management and to support the delivery of skills in community nursing practice. Additionally community nurses identified the knowledge and skills required to develop practice tools that would support areas of generalist and specialist practice, specifically around child welfare and long term conditions (heart care). The five projects were: i. Literature review on case management models in Community Nursing. ii. Action research project to support implementation of Case Management Models in community nursing. iii. Literature review on practitioners with special interest. iv. Research to inform development of practitioner tools for child protection and long term conditions (heart care). v. Research to explore skills transition to support Shifting the Balance of Care. This project focused on 3 key initiatives that are influencing community nursing and it was apparent that they all shared common goals and challenges of implementation. For this reason, it was clear that any development in service provision would impact on, and articulate with, other health, social and profession based changes and could not be implemented in isolation from other related developments that underpin shifting the balance of care. Nurses in the studies articulated insightful challenges for shifting the balance of care, and related role developments, but these were, in the majority, followed by offering practical solutions

Ecological speciation in sympatric palms: 2. Pre- and post-zygotic isolation

We evaluated reproductive isolation in two species of palms (Howea) that have evolved sympatrically on Lord Howe Island (LHI, Australia). We estimated the strength of some pre- and post-zygotic mechanisms in maintaining current species boundaries. We found that flowering time displacement between species is consistent across in and ex situ common gardens and is thus partly genetically determined. On LHI, pre-zygotic isolation due solely to flowering displacement was 97% for Howea belmoreana and 80% for H. forsteriana; this asymmetry results from H. forsteriana flowering earlier than H. belmoreana and being protandrous. As expected, only a few hybrids (here confirmed by genotyping) at both juvenile and adult stages could be detected in two sites on LHI, in which the two species grow intermingled (the Far Flats) or adjacently (Transit Hill). Yet, the distribution of hybrids was different between sites. At Transit Hill, we found no hybrid adult trees, but 13.5% of younger palms examined there were of late hybrid classes. In contrast, we found four hybrid adult trees, mostly of late hybrid classes, and only one juvenile F1 hybrid in the Far Flats. This pattern indicates that selection acts against hybrids between the juvenile and adult stages. An in situ reciprocal seed transplant between volcanic and calcareous soils also shows that early fitness components (up to 36 months) were affected by species and soil. These results are indicative of divergent selection in reproductive isolation, although it does not solely explain the current distribution of the two species on LHI

Gap ratio in anharmonic charge-density-wave systems

Many experimental systems exist that possess charge-density-wave order in their ground state. While this order should be able to be described with models similar to those used for superconductivity, nearly all systems have a ratio of the charge-density-wave order parameter to the transition temperature that is too high for conventional theories. Recent work explained how this can happen in harmonic systems, but when the lattice distortion gets large, anharmonic effects must play an increasingly important role. Here we study the gap ratio for anharmonic charge-density wave systems to see whether the low-temperature properties possess universality as was seen previously in the transition temperature and to see whether the explanation for the large gap ratios survives for anharmonic systems as well.Comment: (5 pages, 3 figures, ReVTeX

Dynamical Chiral Symmetry Breaking on the Light Front.II. The Nambu--Jona-Lasinio Model

An investigation of dynamical chiral symmetry breaking on the light front is made in the Nambu--Jona-Lasinio model with one flavor and N colors. Analysis of the model suffers from extraordinary complexity due to the existence of a "fermionic constraint," i.e., a constraint equation for the bad spinor component. However, to solve this constraint is of special importance. In classical theory, we can exactly solve it and then explicitly check the property of ``light-front chiral transformation.'' In quantum theory, we introduce a bilocal formulation to solve the fermionic constraint by the 1/N expansion. Systematic 1/N expansion of the fermion bilocal operator is realized by the boson expansion method. The leading (bilocal) fermionic constraint becomes a gap equation for a chiral condensate and thus if we choose a nontrivial solution of the gap equation, we are in the broken phase. As a result of the nonzero chiral condensate, we find unusual chiral transformation of fields and nonvanishing of the light-front chiral charge. A leading order eigenvalue equation for a single bosonic state is equivalent to a leading order fermion-antifermion bound-state equation. We analytically solve it for scalar and pseudoscalar mesons and obtain their light-cone wavefunctions and masses. All of the results are entirely consistent with those of our previous analysis on the chiral Yukawa model.Comment: 23 pages, REVTEX, the version to be published in Phys.Rev.D; Some clarifications in discussion of the LC wavefunctions adde

Relativistic Models for Binary Neutron Stars with Arbitrary Spins

We introduce a new numerical scheme for solving the initial value problem for quasiequilibrium binary neutron stars allowing for arbitrary spins. The coupled Einstein field equations and equations of relativistic hydrodynamics are solved in the Wilson-Mathews conformal thin sandwich formalism. We construct sequences of circular-orbit binaries of varying separation, keeping the rest mass and circulation constant along each sequence. Solutions are presented for configurations obeying an n=1 polytropic equation of state and spinning parallel and antiparallel to the orbital angular momentum. We treat stars with moderate compaction ((m/R) = 0.14) and high compaction ((m/R) = 0.19). For all but the highest circulation sequences, the spins of the neutron stars increase as the binary separation decreases. Our zero-circulation cases approximate irrotational sequences, for which the spin angular frequencies of the stars increases by 13% (11%) of the orbital frequency for (m/R) = 0.14 ((m/R) = 0.19) by the time the innermost circular orbit is reached. In addition to leaving an imprint on the inspiral gravitational waveform, this spin effect is measurable in the electromagnetic signal if one of the stars is a pulsar visible from Earth.Comment: 21 pages, 14 figures. A few explanatory sentences added and some typos corrected. Accepted for publication in Phys. Rev.