Amphibia: Anura: Hylidae Scarthyla vigilans (Solano 1971): Range Extension and New Country Record for Trinidad, W.I. With Notes on Tadpoles, Habitat, Behaviour and Biogeographical Significance.

We report a range extension and new country record for Scarthyla vigilans in Trinidad, West Indies. The species was previously known only from populations on mainland South America. We include notes on behavior, habitat and tadpole development, and discuss the biogeographical significance of the species’ presence in Trinidad, particularly with respect to consequences for understanding colonization events on this Caribbean island

Evolution of HCl Concentrations in the Lower Stratosphere from 1991 to 1996 Following the Eruption of Mt. Pinatubo

Geophysical Research Letters, Vol. 25, No. 7, pp. 995-998, April 1, 1998.In situ measurements of hydrochloric acid in the lower stratosphere reveal that its mean abundance relative to that of total inorganic chlorine..

Josephson Coupling and Fiske Dynamics in Ferromagnetic Tunnel Junctions

We report on the fabrication of Nb/AlO_x/Pd_{0.82}Ni_{0.18}/Nb superconductor/insulator/ferromagnetic metal/superconductor (SIFS) Josephson junctions with high critical current densities, large normal resistance times area products, high quality factors, and very good spatial uniformity. For these junctions a transition from 0- to \pi-coupling is observed for a thickness d_F ~ 6 nm of the ferromagnetic Pd_{0.82}Ni_{0.18} interlayer. The magnetic field dependence of the \pi-coupled junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd_{0.82}Ni_{0.18} has an out-of-plane anisotropy and large saturation magnetization, indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes provides information on the junction quality factor and the relevant damping mechanisms up to about 400 GHz. Whereas losses due to quasiparticle tunneling dominate at low frequencies, the damping is dominated by the finite surface resistance of the junction electrodes at high frequencies. High quality factors of up to 30 around 200 GHz have been achieved. Our analysis shows that the fabricated junctions are promising for applications in superconducting quantum circuits or quantum tunneling experiments.Comment: 15 pages, 9 figure

Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

The Kinetics of Primary Alpha Plate Growth in Titanium Alloys

The kinetics of primary alpha-Ti colony/Widmanstatten plate growth from the beta are examined, comparing model to experiment. The plate growth velocity depends sensitively both on the diffusivity D(T) of the rate-limiting species and on the supersaturation around the growing plate. These result in a maxima in growth velocity around 40 K below the transus, once sufficient supersaturation is available to drive plate growth. In Ti-6246, the plate growth velocity was found to be around 0.32 um min-1 at 850 oC, which was in good agreement with the model prediction of 0.36 um min-1 . The solute field around the growing plates, and the plate thickness, was found to be quite variable, due to the intergrowth of plates and soft impingement. This solute field was found to extend to up to 30 nm, and the interface concentration in the beta was found to be around 6.4 at.% Mo. It was found that increasing O content will have minimal effect on the plate lengths expected during continuous cooling; in contrast, Mo approximately doubles the plate lengths obtained for every 2 wt.% Mo reduction. Alloys using V as the beta stabiliser instead of Mo are expected to have much faster plate growth kinetics at nominally equivalent V contents. These findings will provide a useful tool for the integrated design of alloys and process routes to achieve tailored microstructures.Comment: Revised version resubmitted to journa

A software tool for the analysis of C. elegans electropharyngeograms (EPG) (Poster)

Electropharyngeograms (EPG), first established in the group of Leon Avery, are extracellular recordings of the pharyngeal network and provide a readout of both neural and muscular activity. Analysis of EPGs in wild-type and mutant worms has made a significant contribution to the understanding of the molecular and genetic regulation of neural network activity and muscle excitability. In order to facilitate this and allow for higher throughput, and more discrete analysis, we have developed a software tool for the analysis of EPG recordings. Its two main features are, firstly, the automatic detection of pumps, and events within pumps, of an EPG recording, and secondly, the ability to statistically analyse the information acquired at the detection stage. Based on a tailor made signal processing algorithm, the proposed software can detect automatically peaks in the different features of the EPG including those that report the contraction and relaxation of the muscle (the E and R phases, respectively) and those that report the activity of excitatory and inhibitory pharyngeal neurones (the MC spike and the M3 potentials, respectively). Verification of the results by a trained human observer indicates high levels of accuracy. The results of the automatic detection algorithm can also be manually modified, so that alternative interpretations of ambiguous segments of the recordings can be facilitated. Given an annotation of the events within the pumps of the EPG, obtained automatically or otherwise, a statistical analysis of the results is then possible, which is known to be a laborious procedure when performed manually. Information about factors such as pump rate, pump duration, groups of pumps, and number of peaks in each of the E, P and R phases can be readily extracted. While a basic statistical analysis of the above information is possible within the scope of the developed software, its exportation is also possible for further processing with powerful data analysis packages (e.g. Excel, SPSS), that can yield observations about the data set that are not apparent with a mere visual inspection of the recordings. This method allows for a robust, objective and relatively fast definition of pharyngeal phenotypes

In-situ observations of an Antarctic polar stratospheric cloud: Similarities with Arctic observations

Geophysical Research Letters, Vol. 23, pp. 1913-1916, July 15, 1996

Body shape analysis and 2-dimensional cluster representation of C. elegans behaviour: A route to defining complexity in ethanol's modes of action

We present a multi-stage system for analysis of C. elegans behaviour through digital capture of magnified images. Images were acquired using a Hamamatsu digital camera attached to a Nikon SMZ800 stereomicroscope. The system identifies C. elegans on the image then parameterises the worm shape on a frame-by-frame basis. This allows for general features such as heading and speed to be obtained at the same time as intricate details of body shape on a frame-by-frame basis. The system consists of 4 stages: (i) An image de-noising and segmentation / thresholding stage that identifies the worm on each video frame and subtracts the background and segments the worm; (ii) An energy minimisation technique that uses the expectation-maximisation (EM) algorithm to learn a fixed number of Gaussian nodes in a Gaussian mixture model (GMM). The nodes of the GMM distribute themselves along the worm shape derived from the first stage uniformly; (iii) The node centers now represent the parameterised worm shape and are stored on a per frame basis. These parameters are used to provide information regarding instantaneous worm shape and frame-by-frame worm activity; (iv) The worm parameters are clustered using a generative clustering algorithm called Neuroscale, this step allows different worm body shapes to be compared and contrasted in a 2-dimensional visualisation space which displays topographic ordering i.e. similar worm shapes cluster together. Finally, as Neuroscale provides a generative mapping, it is possible to track the trajectory of worm body shapes frame-by-frame over the visualisation space. This means that it now becomes possible to track worm heading, speed and shape over time and to observe and quantify worm behaviour with very fine temporal resolution. The system is designed as a general purpose tool with the possibility of application in a wide variety of behavioural preparations. This approach is currently being used to delineate the effects of ethanol on C. elegans locomotor patterns with the aim of resolving discrete effects at concentrations that are relevant to intoxication rather than sedation (see Dillon et al. this meeting)