Automated identification of Fos expression

The concentration of Fos, a protein encoded by the immediate-early gene c-fos, provides a measure of synaptic activity that may not parallel the electrical activity of neurons. Such a measure is important for the difficult problem of identifying dynamic properties of neuronal circuitries activated by a variety of stimuli and behaviours. We employ two-stage statistical pattern recognition to identify cellular nuclei that express Fos in two-dimensional sections of rat forebrain after administration of antipsychotic drugs. In stage one, we distinguish dark-stained candidate nuclei from image background by a thresholding algorithm and record size and shape measurements of these objects. In stage two, we compare performance of linear and quadratic discriminants, nearest-neighbour and artificial neural network classifiers that employ functions of these measurements to label candidate objects as either Fos nuclei, two touching Fos nuclei or irrelevant background material. New images of neighbouring brain tissue serve as test sets to assess generalizability of the best derived classification rule, as determined by lowest cross-validation misclassification rate. Three experts, two internal and one external, compare manual and automated results for accuracy assessment. Analyses of a subset of images on two separate occasions provide quantitative measures of inter- and intra-expert consistency. We conclude that our automated procedure yields results that compare favourably with those of the experts and thus has potential to remove much of the tedium, subjectivity and irreproducibility of current Fos identification methods in digital microscopy

Sum rules in the oscillator radiation processes

We consider the problem of an harmonic oscillator coupled to a scalar field in the framework of recently introduced dressed coordinates. We compute all the probabilities associated with the decay process of an excited level of the oscillator. Instead of doing direct quantum mechanical calculations we establish some sum rules from which we infer the probabilities associated to the different decay processes of the oscillator. Thus, the sum rules allows to show that the transition probabilities between excited levels follow a binomial distribution.Comment: comments and references added, LaTe

Dressed coordinates: the path-integrals approach

The recent introduced \textit{dressed coordinates} are studied in the path-integral approach. These coordinates are defined in the context of a harmonic oscillator linearly coupled to massless scalar field and, it is shown that in this model the dressed coordinates appear as a coordinate transformation preserving the path-integral functional measure. The analysis also generalizes the \textit{sum rules} established in a previous work.Comment: 9 pages, Latex2

The Impact of Interorganizational Imitation on New Venture International Entry and Performance

We examine the impact of interorganizational imitation on new venture international entry and subsequent performance. Using a sample of 150 U.S.-based publicly held new ventures, we find that new venture international entry is in part an imitative response to the internationalization of other firms in the venture\u27s home country industry and/or subsets of firms with certain traits or outcomes. We also find that interorganizational imitation moderates the relationship between new venture international entry and profitability, but not the relationship between new venture international entry and sales growth. These findings contribute to the growing body of literature on new venture internationalization

Real Time Turbulent Video Perfecting by Image Stabilization and Super-Resolution

Image and video quality in Long Range Observation Systems (LOROS) suffer from atmospheric turbulence that causes small neighbourhoods in image frames to chaotically move in different directions and substantially hampers visual analysis of such image and video sequences. The paper presents a real-time algorithm for perfecting turbulence degraded videos by means of stabilization and resolution enhancement. The latter is achieved by exploiting the turbulent motion. The algorithm involves generation of a reference frame and estimation, for each incoming video frame, of a local image displacement map with respect to the reference frame; segmentation of the displacement map into two classes: stationary and moving objects and resolution enhancement of stationary objects, while preserving real motion. Experiments with synthetic and real-life sequences have shown that the enhanced videos, generated in real time, exhibit substantially better resolution and complete stabilization for stationary objects while retaining real motion.Comment: Submitted to The Seventh IASTED International Conference on Visualization, Imaging, and Image Processing (VIIP 2007) August, 2007 Palma de Mallorca, Spai

Purpose and enactment in job design: An empirical examination of the processes through which job characteristics have their effects

Job characteristics are linked with health, safety, well-being and other performance outcomes. Job characteristics are usually assessed by their presence or absence, which gives no indication of the specific purposes for which workers might use some job characteristics. We focused on job control and social support as two job characteristics embedded in the well-known Demand-Control-Support model (Karasek & Theorell, 1990). In Study 1, using an experience sampling methodology (N = 67) and a cross-sectional survey methodology (N = 299), we found that relationships between the execution of job control or the elicitation of social support and a range of other variables depended on the purposes for which job control was executed or social support elicited. In Study 2 (N = 28), we found that it may be feasible to improve aspects of well-being and performance through training workers on how to use job control or social support for specific purposes

Grassmann Variables and the Jaynes-Cummings Model

This paper shows that phase space methods using a positive P type distribution function involving both c-number variables (for the cavity mode) and Grassmann variables (for the two level atom) can be used to treat the Jaynes-Cummings model. Although it is a Grassmann function, the distribution function is equivalent to six c-number functions of the two bosonic variables. Experimental quantities are given as bosonic phase space integrals involving the six functions. A Fokker-Planck equation involving both left and right Grassmann differentiation can be obtained for the distribution function, and is equivalent to six coupled equations for the six c-number functions. The approach used involves choosing the canonical form of the (non-unique) positive P distribution function, where the correspondence rules for bosonic operators are non-standard and hence the Fokker-Planck equation is also unusual. Initial conditions, such as for initially uncorrelated states, are used to determine the initial distribution function. Transformations to new bosonic variables rotating at the cavity frequency enables the six coupled equations for the new c-number functions (also equivalent to the canonical Grassmann distribution function) to be solved analytically, based on an ansatz from a 1980 paper by Stenholm. It is then shown that the distribution function is the same as that determined from the well-known solution based on coupled equations for state vector amplitudes of atomic and n-photon product states. The treatment of the simple two fermion mode Jaynes-Cummings model is a useful test case for the future development of phase space Grassmann distribution functional methods for multi-mode fermionic applications in quantum-atom optics.Comment: 57 pages, 0 figures. Version

Coercive redistribution and public agreement: re-evaluating the libertarian challenge of charity

In this article, we evaluate the capacity of liberal egalitarianism to rebut what we call the libertarian challenge of charity. This challenge states that coercive redistributive taxation is neither needed nor justified, since those who endorse redistribution can give charitably, and those who do not endorse redistribution cannot justifiably be coerced. We argue that contemporary developments in liberal political thought render liberalism more vulnerable to this libertarian challenge. Many liberals have, in recent years, sought to recast liberalism such that it is more hospitable to cultural, religious, and ethnic diversity. This move has resulted in increased support for the claim that liberalism should be understood as a political rather than comprehensive doctrine, and that liberal institutions should draw their legitimacy from agreements made among members of an appropriately conceived deliberative community, rather than from controversial liberal principles like individual autonomy. We argue that, while this move may indeed make liberalism more compatible with cultural diversity, it also makes it more vulnerable to the libertarian challenge of charity. Not all versions of liberalism are troubled by the challenge, but those that are troubled by it are increasingly dominant. We also discuss G. A. Cohen’s claim that liberal equality requires an ‘egalitarian ethos’ and argue that, if Cohen is right, it is difficult to see how there can be an adequate response to the libertarian challenge of charity. In general, our argument can be summarised as follows: the more that liberalism is concerned accurately to model the actual democratic wishes and motivations of the people it governs, the less it is able to justify coercively imposing redistributive principles of justice

Chronic Stress, Sense of Belonging, and Depression Among Survivors of Traumatic Brain Injury

To test whether chronic stress, interpersonal relatedness, and cognitive burden could explain depression after traumatic brain injury (TBI). Design : A nonprobability sample of 75 mild-to-moderately injured TBI survivors and their significant others, were recruited from five TBI day-rehabilitation programs. All participants were within 2 years of the date of injury and were living in the community. Methods : During face-to-face interviews, demographic information, and estimates of brain injury severity were obtained and participants completed a cognitive battery of tests of directed attention and short-term memory, responses to the Perceived Stress Scale, Interpersonal Relatedness Inventory, Sense of Belonging Instrument, Neurobehavioral Functioning Inventory, and Center for Epidemiological Studies Depression Scale;. Findings : Chronic stress was significantly and positively related to post-TBI depression. Depression and postinjury sense of belonging were negatively related. Social support and results from the cognitive battery did not explain depression. Conclusions : Postinjury chronic stress and sense of belonging were strong predictors of post-injury depression and are variables amenable to interventions by nurses in community health, neurological centers, or rehabilitation clinics. Future studies are needed to examine how these variables change over time during the recovery process.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72593/1/j.1547-5069.2002.00221.x.pd

Neutralino Pair Production and 3-Body Decays at e+e−e^+e^- Linear Colliders as Probes of CP Violation in the Neutralino System

In the CP-invariant supersymmetric theories, the steep S-wave (slow P-wave) rise of the cross section for any non-diagonal neutralino pair production in $e^+ e^-$ annihilation, $e^+e^- \to \tilde{\chi}^0_i \tilde{\chi}^0_j$ ($i \neq j$), near threshold is accompanied by the slow P-wave (steep S-wave) decrease of the fermion invariant mass distribution of the 3-body neutralino decay, $\tilde{\chi}^0_i \to \tilde{\chi}^0_j f\bar{f}$ ($f=l$ or $q$), near the end point. These selection rules, unique to the neutralino system due to its Majorana nature, guarantee that the observation of simultaneous sharp S-wave excitations of the production cross section near threshold and the lepton and quark invariant mass distribution near the end point is a qualitative, unambiguous evidence for CP violation in the neutralino system.Comment: 11 pages, 1 eps figure, a reference adde