Leptoquarks and the HERA High-Q2 Events

The excess of high-Q2 events recently observed in deep-inelastic positron-proton scattering at HERA has refuelled speculations on physics beyond the standard model, in particular on low-mass leptoquark-type particles. We review the theoretical framework for leptoquark interactions, and their production and decay at HERA. Bounds on leptoquark masses and couplings, and implications on other experiments are also discussed.Comment: 18 pages, Latex, 5 postscript figures included, Talk presented by R. Rueckl at the Ringberg Workshop on Physics beyond the Standard Model, Beyond the Desert, June 8--14, 1997, Tegernsee, German

Production of Heavy Bound States at LEP and Beyond

We describe some characteristic properties of $B_c$ mesons and discuss the production and the prospects of detection in $e^+ e^-$, $\gamma \gamma$, and $\bar pp/pp$ collisions. The production mechanisms considered here also play an important role in charmonium and bottomonium production.Comment: 10 pages, MPI-PhT/94-41,LMU-10/94, Normalization in figure 6 and discussion to figure 6 change

R-Parity Violating SUSY Signals in Lepton-Pair Production at the Tevatron

In supersymmetric theories with R-parity breaking, sleptons can be produced in quark-antiquark annihilation at the Tevatron through interactions in which two quark fields are coupled to a slepton field. If at the same time trilinear slepton-lepton-lepton couplings are present, the sleptons can be searched for as resonances in $p\bar{p}\to \tilde{\nu} \to l^+l^-$ and $\tilde{\tau}\to l\nu$ final states. Existing Tevatron data can be exploited to derive bounds on the Yukawa couplings of sleptons to quark and lepton pairs. Similar bounds can also be obtained from $e^+e^-$ annihilation to hadrons at LEP2.Comment: LaTeX file, 12 pages, 4 figures, uses epsfig, axodra

Toward the next generation of research into small area effects on health : a synthesis of multilevel investigations published since July 1998.

To map out area effects on health research, this study had the following aims: (1) to inventory multilevel investigations of area effects on self rated health, cardiovascular diseases and risk factors, and mortality among adults; (2) to describe and critically discuss methodological approaches employed and results observed; and (3) to formulate selected recommendations for advancing the study of area effects on health. Overall, 86 studies were inventoried. Although several innovative methodological approaches and analytical designs were found, small areas are most often operationalised using administrative and statistical spatial units. Most studies used indicators of area socioeconomic status derived from censuses, and few provided information on the validity and reliability of measures of exposures. A consistent finding was that a significant portion of the variation in health is associated with area context independently of individual characteristics. Area effects on health, although significant in most studies, often depend on the health outcome studied, the measure of area exposure used, and the spatial scale at which associations are examined

Why are “What” and “Where” Processed by Separate Cortical Visual Systems? A Computational Investigation

In the primate visual system, the identification of objects and the processing of spatial information are accomplished by different cortical pathways. The computational properties of this “two-systems” design were explored by constructing simplifying connectionist models. The models were designed to simultaneously classify and locate shapes that could appear in multiple positions in a matrix, and the ease of forming representations of the two kinds of information was measured. Some networks were designed so that all hidden nodes projected to all output nodes, whereas others had the hidden nodes split into two groups, with some projecting to the output nodes that registered shape identity and the remainder projecting to the output nodes that registered location. The simulations revealed that splitting processing into separate streams for identifying and locating a shape led to better performance only under some circumstances. Provided that enough computational resources were available in both streams, split networks were able to develop more efficient internal representations, as revealed by detailed analyses of the patterns of weights between connections.Psycholog

Leptoquark/Squark Interpretation of HERA Events: Virtual Effects in e+e- Annihilation to Hadrons

In reference to the recently observed high Q^2, large x events in deep-inelastic positron-proton scattering at HERA, various leptoquark and supersymmetric scenarios are discussed. We study the impact of virtual leptoquark or R-parity breaking squark exchange as well as generic contact interaction on the production of quark-antiquark pairs in $e^+e^-$ annihilation, in particular at LEP2.Comment: LaTeX file, 20 pages, 7 figures, uses epsfig, typos fixed, a few general references adde

What do fully-visible primes and brain potentials reveal about morphological decomposition?

This is the author's post-print version of an article published in Psychophysiology, 2011, Vol. 48, Issue 5, pp. 676 – 686. Copyright © 2011 Wiley-Blackwell. The definitive version is available at www3.interscience.wiley.comTo examine the role of meaning in morphological decomposition ({re-}+{play}), researchers have employed the priming paradigm. Perceptually masked primes lead to facilitation both when decomposition is semantically appropriate (hunter-HUNT) and when it is not (corner-CORN), whereas with fully visible primes facilitation is observed only in the former case. We investigated the N400 brain potential time-locked to words preceded by fully visible primes. At ∼300–380 ms, N400 was equally attenuated in the semantically “transparent” condition (hunter-HUNT) and semantically “opaque” condition (corner-CORN). In the transparent condition, N400 remained attenuated after 380 ms, whereas in the opaque condition it returned to the level of a nonmorphological form condition (brothel-BROTH). This pattern of N400 priming is consistent with an orthography-based, morphological decomposition mechanism, “licensed” at a later stage by semantic information.This research was supported by a Ph.D. studentship from the UK Economic and Social Research Council (ESRC) to the third author. The second author was supported by research grants from the Leverhulme Trust (F/07 537/AB) and the Economic and Social Research Council (RES-062-23-2268)

SamuROI, a Python-Based Software Tool for Visualization and Analysis of Dynamic Time Series Imaging at Multiple Spatial Scales

The measurement of activity in vivo and in vitro has shifted from electrical to optical methods. While the indicators for imaging activity have improved significantly over the last decade, tools for analysing optical data have not kept pace. Most available analysis tools are limited in their flexibility and applicability to datasets obtained at different spatial scales. Here, we present SamuROI (Structured analysis of multiple user-defined ROIs), an open source Python-based analysis environment for imaging data. SamuROI simplifies exploratory analysis and visualization of image series of fluorescence changes in complex structures over time and is readily applicable at different spatial scales. In this paper, we show the utility of SamuROI in Ca2+-imaging based applications at three spatial scales: the micro-scale (i.e., sub-cellular compartments including cell bodies, dendrites and spines); the meso-scale, (i.e., whole cell and population imaging with single-cell resolution); and the macro-scale (i.e., imaging of changes in bulk fluorescence in large brain areas, without cellular resolution). The software described here provides a graphical user interface for intuitive data exploration and region of interest (ROI) management that can be used interactively within Jupyter Notebook: a publicly available interactive Python platform that allows simple integration of our software with existing tools for automated ROI generation and post-processing, as well as custom analysis pipelines. SamuROI software, source code and installation instructions are publicly available on GitHub and documentation is available online. SamuROI reduces the energy barrier for manual exploration and semi-automated analysis of spatially complex Ca2+ imaging datasets, particularly when these have been acquired at different spatial scales.Peer Reviewe