Omega-3 Fatty Acids Improve Recovery, whereas Omega-6 Fatty Acids Worsen Outcome, after Spinal Cord Injury in the Adult Rat

Spinal cord injury (SCI) is a cause of major neurological disability, and no satisfactory treatment is currently available. Evidence suggests that polyunsaturated fatty acids (PUFAs) could target some of the pathological mechanisms that underlie damage after SCI. We examined the effects of treatment with PUFAs after lateral spinal cord hemisection in the rat. The ω-3 PUFAs α-linolenic acid and docosahexaenoic acid (DHA) injected 30 min after injury induced significantly improved locomotor performance and neuroprotection, including decreased lesion size and apoptosis and increased neuronal and oligodendrocyte survival. Evidence showing a decrease in RNA/DNA oxidation suggests that the neuroprotective effect of ω-3 PUFAs involved a significant antioxidant function. In contrast, animals treated with arachidonic acid, an ω-6 PUFA, had a significantly worse outcome than controls. We confirmed the neuroprotective effect of ω-3 PUFAs by examining the effects of DHA treatment after spinal cord compression injury. Results indicated that DHA administered 30 min after spinal cord compression not only greatly increased survival of neurons but also resulted in significantly better locomotor performance for up to 6 weeks after injury. This report shows a striking difference in efficacy between the effects of treatment with ω-3 and ω-6 PUFAs on the outcome of SCI, with ω-3 PUFAs being neuroprotective and ω-6 PUFAs having a damaging effect. Given the proven clinical safety of ω-3 PUFAs, our observations show that these PUFAs have significant therapeutic potential in SCI. In contrast, the use of preparations enriched in ω-6 PUFAs after injury could worsen outcome after SCI

School-based curriculum development in Scotland: Curriculum policy and enactment

Recent worldwide trends in curriculum policy have re-emphasised the role of teachers in school-based curriculum development. Scotland’s Curriculum for Excellence is typical of these trends, stressing that teachers are agents of change. This paper draws upon empirical data to explore school-based curriculum development in response to Curriculum for Excellence. We focus on two case studies – secondary schools within a single Scottish local education authority. In the paper we argue that the nature and extent of innovation in schools is dependent upon teachers being able to make sense of often complex and confusing curriculum policy, including the articulation of a clear vision about what such policy means for education within each school

An optical fiber photoplethysmographic system for central nervous system tissue

A new system for measuring the oxygen saturation of blood within tissue has been developed, for a number of potential patient monitoring applications. This proof of concept project aims to address the unmet need of real-time measurement of oxygen saturation in the central nervous system (CNS) for patients recovering from neurosurgery or trauma, by developing a fiber optic signal acquisition system for internal placement through small apertures. The development and testing of a two-wavelength optical fiber reflectance photoplethysmography (PPG) system is described. It was found that good quality red and near-infrared PPG signals could be consistently obtained from the human fingertip (n=6) and rat spinal cord (n=6) using the fiber optic probe. These findings justify further development and clinical evaluation of this fiber optic system

Variation of rayleigh wave group velocity dispersion and seismic heterogeneity of the Indian crust and uppermost mantle

We present group velocity dispersion results from a study of regional fundamental mode Rayleigh waves propagating across the Indian region. 1-D, path-averaged dispersion measurements have been made for 1001 source-receiver paths and these combined to produce tomographic images between 15 and 45 s period. Because of the dense station coverage in peninsular India, these images have substantially higher lateral resolution for this region than is currently available from global and regional group velocity studies. Testing of the group velocity model shows that the average resolution across the region is about 7.5° for the periods used in this study. The tomographic maps demonstrate that while the Indian shield is characterized by high crustal and uppermost-mantle group velocities, comparatively lower velocities exist beneath the Himalaya due to the thickened crust and beneath the Gangetic plains caused by the mollasse sediments and recent alluvium cover in the Himalayan foredeep. Northeastern India north of the Shillong Plateau also displays higher velocities, similar to the south Indian shield, indicative of colder crust beneath the region. The northern Bay of Bengal shows extremely low velocities due to the thick sediment blanket of the Bengal fan. Likewise, the Katawaz Basin in southern Pakistan shows lower velocities that resemble those seen in the Bay of Bengal. The geometry of the velocity contours south of the Katawaz Basin closely matches the prograding Indus fan in the Arabian Sea. Finally, the Tibetan Plateau has lower group velocities compared to the Indian shield at all periods as a result of the thick crust beneath southern Tibet

Point process model of 1/f noise versus a sum of Lorentzians

We present a simple point process model of $1/f^{\beta}$ noise, covering different values of the exponent $\beta$. The signal of the model consists of pulses or events. The interpulse, interevent, interarrival, recurrence or waiting times of the signal are described by the general Langevin equation with the multiplicative noise and stochastically diffuse in some interval resulting in the power-law distribution. Our model is free from the requirement of a wide distribution of relaxation times and from the power-law forms of the pulses. It contains only one relaxation rate and yields $1/f^ {\beta}$ spectra in a wide range of frequency. We obtain explicit expressions for the power spectra and present numerical illustrations of the model. Further we analyze the relation of the point process model of $1/f$ noise with the Bernamont-Surdin-McWhorter model, representing the signals as a sum of the uncorrelated components. We show that the point process model is complementary to the model based on the sum of signals with a wide-range distribution of the relaxation times. In contrast to the Gaussian distribution of the signal intensity of the sum of the uncorrelated components, the point process exhibits asymptotically a power-law distribution of the signal intensity. The developed multiplicative point process model of $1/f^{\beta}$ noise may be used for modeling and analysis of stochastic processes in different systems with the power-law distribution of the intensity of pulsing signals.Comment: 23 pages, 10 figures, to be published in Phys. Rev.

Identifying phase synchronization clusters in spatially extended dynamical systems

We investigate two recently proposed multivariate time series analysis techniques that aim at detecting phase synchronization clusters in spatially extended, nonstationary systems with regard to field applications. The starting point of both techniques is a matrix whose entries are the mean phase coherence values measured between pairs of time series. The first method is a mean field approach which allows to define the strength of participation of a subsystem in a single synchronization cluster. The second method is based on an eigenvalue decomposition from which a participation index is derived that characterizes the degree of involvement of a subsystem within multiple synchronization clusters. Simulating multiple clusters within a lattice of coupled Lorenz oscillators we explore the limitations and pitfalls of both methods and demonstrate (a) that the mean field approach is relatively robust even in configurations where the single cluster assumption is not entirely fulfilled, and (b) that the eigenvalue decomposition approach correctly identifies the simulated clusters even for low coupling strengths. Using the eigenvalue decomposition approach we studied spatiotemporal synchronization clusters in long-lasting multichannel EEG recordings from epilepsy patients and obtained results that fully confirm findings from well established neurophysiological examination techniques. Multivariate time series analysis methods such as synchronization cluster analysis that account for nonlinearities in the data are expected to provide complementary information which allows to gain deeper insights into the collective dynamics of spatially extended complex systems

Working, travelling, and identity: J.B. Priestley’s English Journey (1934)

The motivation for travel is central to its form and content. This article addresses an under-represented area of travel writing: the travel text that results from a journey undertaken for work purposes. By considering J. B. Priestley’s English Journey as a case-study, it argues that the text’s critical reception, at first disorientated and confused, and later dominated by historical and political readings, has resulted from Priestley’s emphasis on work rather than leisure. In his text Priestley explores the relationship of work and identity, and his own position as writer and traveller is central to this, symbolised in his preoccupation with the figure of the travelling salesman

Dynamic Critical Behavior of the Swendsen-Wang Algorithm: The Two-Dimensional 3-State Potts Model Revisited

We have performed a high-precision Monte Carlo study of the dynamic critical behavior of the Swendsen-Wang algorithm for the two-dimensional 3-state Potts model. We find that the Li-Sokal bound ($\tau_{int,E} \geq const \times C_H$) is almost but not quite sharp. The ratio $\tau_{int,E} / C_H$ seems to diverge either as a small power ($\approx 0.08$) or as a logarithm.Comment: 35 pages including 3 figures. Self-unpacking file containing the LaTeX file, the needed macros (epsf.sty, indent.sty, subeqnarray.sty, and eqsection.sty) and the 3 Postscript figures. Revised version fixes a normalization error in \xi (with many thanks to Wolfhard Janke for finding the error!). To be published in J. Stat. Phys. 87, no. 1/2 (April 1997

Error estimation and reduction with cross correlations

Besides the well-known effect of autocorrelations in time series of Monte Carlo simulation data resulting from the underlying Markov process, using the same data pool for computing various estimates entails additional cross correlations. This effect, if not properly taken into account, leads to systematically wrong error estimates for combined quantities. Using a straightforward recipe of data analysis employing the jackknife or similar resampling techniques, such problems can be avoided. In addition, a covariance analysis allows for the formulation of optimal estimators with often significantly reduced variance as compared to more conventional averages.Comment: 16 pages, RevTEX4, 4 figures, 6 tables, published versio