A multi-wavelength access network featuring WiMAX transmission over GPON links

“This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder." “Copyright IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.”An IEEE802.16e compliant PON architecture with wavelength band overlay has been demonstrated. Transparent transmission of mobile-WiMAX RF channels over multi-wavelength GPON links, based on FDM, has demonstrated at remote receivers standard WiMAX EVM figures with 1E-11 GPON bit-error-rates

Demonstration of wireless backhauling over long-reach PONs

An IEEE 802.16e-2005 (WiMAX) compliant, longreach passive optical network is demonstrated, focusing on the development of next generation optical access with transparent wireless backhauling. In addition to the extended feeder reach, a wavelength band overlay is used to enhance network scalability by maintaining passive splitting in the field and with some design modification at the optical line terminal and remote base station. Radio-over-fiber is used to minimize network installation and maintenance costs through the use of simple remote radio heads complemented by frequency division multiplexing to address individual base stations. The implementation of overlapping radio cells/sectors is also proposed to provide joint signal processing at wireless user terminals. Experimental measurements confirmed EVMs below -30 and -23 dB downstream and upstream, respectively, over fiber link lengths of up to 84.6 km. In addition, adjacent channel leakage ratio measurements demonstrated that a figure of -45 dB with 40 MHz subcarrier spacing, as specified by the standard, can be readily achieved.Peer reviewe

Adaptive Optimisation of Illumination Beam Profiles in Fluorescence Microscopy

Wide-field fluorescence microscope techniques such as single/selective plane illumination microscope (SPIM) are typically configured to image large regions of a sample at once. Here the illumination beam provides uniform excitation of several biological features across the region, `sliced' to a thickness of between 5-10 microns. In this paper we propose a simple alteration to the optical configuration of a SPIM by switching the light-sheet- forming cylindrical lens with a spatial light modulator. This has the potential to adaptively reconfigure the light sheet geometry to improve the optical sectioning of specific biological features, rather than the thicker sectioning of several features at once across a larger observation field-of-view. We present a prototype version of such a system, referred to as an Adaptive-SPIM (A-SPIM) system. We then suggest that the direct recording of illumination beam shapes within the working microscope system can better facilitate the analysis and subsequent re-configuration of the illumination beam to a specific geometry, and summarise the design and operation of a device that we have developed specifically for this purpose. We finally present reconstructed quantitative three dimensional flux maps of illumination beams from three microscope configurations taken using this miniature high-dynamic range beam profiling device, comparing the beam geometry of a regular SPIM system with our prototype A-SPIM system, and suggesting future improvements

Forecasting time series by means of evolutionary algorithms

Proceeding of: 8th International Conference in Parallel Problem Solving from Nature - PPSN VIII , Birmingham, UK, September 18-22, 2004.The time series forecast is a very complex problem, consisting in predicting the behaviour of a data series with only the information of the previous sequence. There is many physical and artificial phenomenon that can be described by time series. The prediction of such phenomenon could be very complex. For instance, in the case of tide forecast, unusually high tides, or sea surges, result from a combination of chaotic climatic elements in conjunction with the more normal, periodic, tidal systems associated with a particular area. Too much variables influence the behaviour of the water level. Our problem is not only to find prediction rules, we also need to discard the noise and select the representative data. Our objective is to generate a set of prediction rules. There are many methods tying to achieve good predictions. In most of the cases this methods look for general rules that are able to predict the whole series. The problem is that usually the time series has local behaviours that dont allow a good level of prediction when using general rules. In this work we present a method for finding local rules able to predict only some zones of the series but achieving better level prediction. This method is based on the evolution of set of rules genetically codified, and following the Michigan approach. For evaluating the proposal, two different domains have been used: an artificial domain widely use in the bibliography (Mackey-Glass series) and a time series corresponding to a natural phenomenon, the water level in Venice Lagoon.Investigation supported by the Spanish Ministry of Science and Technology through the TRACER project under contract TIC2002-04498-C05-

Radiation Damage of F8 Lead Glass with 20 MeV Electrons

Using a 20 MeV linear accelerator, we investigate the effects of electromagnetic radiation on the optical transparency of F8 lead glass. Specifically, we measure the change in attenuation length as a function of radiation dose. Comparing our results to similar work that utilized a proton beam, we conclude that F8 lead glass is more susceptible to proton damage than electron damage.Comment: 5 pages, 6 figure

Associations between the composition of daily time spent in physical activity, sedentary behaviour and sleep and risk of depression: compositional data analyses of the 1970 British cohort study

Background The benefits of moderate to vigorous physical activity(MVPA) in lowering depression risk are well established, but there is mixed evidence on sleep, sedentary behaviour(SB), and light-intensity physical activity(LIPA). These behaviours are often considered in isolation, neglecting their behavioural and biological interdependences. We investigated how time spent in one behaviour relative to others was associated with depression risk. Methods We included 4738 individuals from the 1970 British Cohort study (age 46 wave). Depression status was ascertained using self-reported doctor visits and prescribed anti-depressant use. MVPA, LIPA, SB and sleep were ascertained using thigh-worn accelerometers worn consecutively for 7 days. Compositional logistic regression was used to examine associations between different compositions of time spent in movement behaviours and depression. Results More time spent in MVPA, relative to SB, sleep or LIPA, was associated with a lower risk of depression. When modelling reallocation of time (e.g. replacing time in one behaviour with another), replacing sleep, SB or LIPA with MVPA time was strongly associated with lower depression risk. Reallocating time between SB, sleep or LIPA had minimal to no effect. Limitations Data was cross-sectional, therefore causality cannot be inferred. Accelerometers do not capture SB context (e.g. TV watching, reading) nor separate biological sleep from time spent in bed. Conclusions Displacing any behaviour with MVPA was associated with a lower risk of depression. This study provides promising support that increasing MVPA, even in small doses, can have a positive impact on prevention, mitigation and treatment of depression

Apparent Superluminal Behavior

The apparent superluminal propagation of electromagnetic signals seen in recent experiments is shown to be the result of simple and robust properties of relativistic field equations. Although the wave front of a signal passing through a classically forbidden region can never move faster than light, an attenuated replica of the signal is reproduced ``instantaneously'' on the other side of the barrier. The reconstructed signal, causally connected to the forerunner rather than the bulk of the input signal, appears to move through the barrier faster than light.Comment: 8 pages, no figure

Proprioceptive contribution to oculomotor control in humans

This work was supported by an award from the Wellcome Trust Institutional Strategic Support Fund at the University of St Andrews, grant code 204821/Z/16/Z (DB).Stretch receptors in the extraocular muscles (EOMs) inform the central nervous system about the rotation of one's own eyes in the orbits. Whereas fine control of the skeletal muscles hinges critically on proprioceptive feedback, the role of proprioception in oculomotor control remains unclear. Human behavioural studies provide evidence for EOM proprioception in oculomotor control, however, behavioural and electrophysiological studies in the macaque do not. Unlike macaques, humans possess numerous muscle spindles in their EOMs. To find out whether the human oculomotor nuclei respond to proprioceptive feedback we used functional magnetic resonance imaging (fMRI). With their eyes closed, participants placed their right index finger on the eyelid at the outer corner of the right eye. When prompted by a sound, they pushed the eyeball gently and briefly towards the nose. Control conditions separated out motor and tactile task components. The stretch of the right lateral rectus muscle was associated with activation of the left oculomotor nucleus and subthreshold activation of the left abducens nucleus. Because these nuclei control the horizontal movements of the left eye, we hypothesized that proprioceptive stimulation of the right EOM triggered left eye movement. To test this, we followed up with an eye-tracking experiment in complete darkness using the same behavioural task as in the fMRI study. The left eye moved actively in the direction of the passive displacement of the right eye, albeit with a smaller amplitude. Eye tracking corroborated neuroimaging findings to suggest a proprioceptive contribution to ocular alignment.Publisher PDFPeer reviewe

The impact of fuel properties on the emissions from the combustion of biomass and other solid fuels in a fixed bed domestic stove

Experimental results are presented on the emissions from a single combustion chamber stove burning wood, coal and processed fuels. This technique was used to permit comparisons to be made of the influence of different fuel types without it being influenced by the effects of secondary combustion. Measurements were made of CO, NOx and fine particulates during the major phases of combustion, namely flaming and smouldering. Measurements of the particulates were made in two ways: firstly using a gravimetric total particulate measurement and secondly using a cyclone technique to give PM2.5 and PM10 size fractions. Smoke emissions from the different fuels were very dependent on the phase of combustion especially for the total particulate results, where flaming phase emissions were much higher than in the smouldering phase. It was found that the particulate emission factors for the wood fuels were dependent on the volatile content whilst the coals followed a different pattern. NOx was linearly dependent on the fuel-N content for all the fuel types, but the relationship for biomass is different from that for coal. CO emissions were very dependent on the combustion phase