Spectrotemporal dynamics of auditory cortical synaptic receptive field plasticity.

Science.gov (United States)

Froemke, Robert C; Martins, Ana Raquel O

2011-09-01

The nervous system must dynamically represent sensory information in order for animals to perceive and operate within a complex, changing environment. Receptive field plasticity in the auditory cortex allows cortical networks to organize around salient features of the sensory environment during postnatal development, and then subsequently refine these representations depending on behavioral context later in life. Here we review the major features of auditory cortical receptive field plasticity in young and adult animals, focusing on modifications to frequency tuning of synaptic inputs. Alteration in the patterns of acoustic input, including sensory deprivation and tonal exposure, leads to rapid adjustments of excitatory and inhibitory strengths that collectively determine the suprathreshold tuning curves of cortical neurons. Long-term cortical plasticity also requires co-activation of subcortical neuromodulatory control nuclei such as the cholinergic nucleus basalis, particularly in adults. Regardless of developmental stage, regulation of inhibition seems to be a general mechanism by which changes in sensory experience and neuromodulatory state can remodel cortical receptive fields. We discuss recent findings suggesting that the microdynamics of synaptic receptive field plasticity unfold as a multi-phase set of distinct phenomena, initiated by disrupting the balance between excitation and inhibition, and eventually leading to wide-scale changes to many synapses throughout the cortex. These changes are coordinated to enhance the representations of newly-significant stimuli, possibly for improved signal processing and language learning in humans. Copyright © 2011 Elsevier B.V. All rights reserved.

A second-order orientation-contrast stimulus for population-receptive-field-based retinotopic mapping.

Science.gov (United States)

Yildirim, Funda; Carvalho, Joana; Cornelissen, Frans W

2018-01-01

Visual field or retinotopic mapping is one of the most frequently used paradigms in fMRI. It uses activity evoked by position-varying high luminance contrast visual patterns presented throughout the visual field for determining the spatial organization of cortical visual areas. While the advantage of using high luminance contrast is that it tends to drive a wide range of neural populations - thus resulting in high signal-to-noise BOLD responses - this may also be a limitation, especially for approaches that attempt to squeeze more information out of the BOLD response, such as population receptive field (pRF) mapping. In that case, more selective stimulation of a subset of neurons - despite reduced signals - could result in better characterization of pRF properties. Here, we used a second-order stimulus based on local differences in orientation texture - to which we refer as orientation contrast - to perform retinotopic mapping. Participants in our experiment viewed arrays of Gabor patches composed of a foreground (a bar) and a background. These could only be distinguished on the basis of a difference in patch orientation. In our analyses, we compare the pRF properties obtained using this new orientation contrast-based retinotopy (OCR) to those obtained using classic luminance contrast-based retinotopy (LCR). Specifically, in higher order cortical visual areas such as LO, our novel approach resulted in non-trivial reductions in estimated population receptive field size of around 30%. A set of control experiments confirms that the most plausible cause for this reduction is that OCR mainly drives neurons sensitive to orientation contrast. We discuss how OCR - by limiting receptive field scatter and reducing BOLD displacement - may result in more accurate pRF localization as well. Estimation of neuronal properties is crucial for interpreting cortical function. Therefore, we conclude that using our approach, it is possible to selectively target particular neuronal

Disinhibition outside receptive fields in the visual cortex.

Science.gov (United States)

Walker, Gary A; Ohzawa, Izumi; Freeman, Ralph D

2002-07-01

By definition, the region outside the classical receptive field (CRF) of a neuron in the visual cortex does not directly activate the cell. However, the response of a neuron can be influenced by stimulation of the surrounding area. In previous work, we showed that this influence is mainly suppressive and that it is generally limited to a local region outside the CRF. In the experiments reported here, we investigate the mechanisms of the suppressive effect. Our approach is to find the position of a grating patch that is most effective in suppressing the response of a cell. We then use a masking stimulus at different contrasts over the grating patch in an attempt to disinhibit the response. We find that suppressive effects may be partially or completely reversed by use of the masking stimulus. This disinhibition suggests that effects from outside the CRF may be local. Although they do not necessarily underlie the perceptual analysis of a figure-ground visual scene, they may provide a substrate for this process.

Cortico-Cortical Receptive Field Estimates in Human Visual Cortex

Directory of Open Access Journals (Sweden)

Koen V Haak

2012-05-01

Full Text Available Human visual cortex comprises many visual areas that contain a map of the visual field (Wandell et al 2007, Neuron 56, 366–383. These visual field maps can be identified readily in individual subjects with functional magnetic resonance imaging (fMRI during experimental sessions that last less than an hour (Wandell and Winawer 2011, Vis Res 718–737. Hence, visual field mapping with fMRI has been, and still is, a heavily used technique to examine the organisation of both normal and abnormal human visual cortex (Haak et al 2011, ACNR, 11(3, 20–21. However, visual field mapping cannot reveal every aspect of human visual cortex organisation. For example, the information processed within a visual field map arrives from somewhere and is sent to somewhere, and visual field mapping does not derive these input/output relationships. Here, we describe a new, model-based analysis for estimating the dependence between signals in distinct cortical regions using functional magnetic resonance imaging (fMRI data. Just as a stimulus-referred receptive field predicts the neural response as a function of the stimulus contrast, the neural-referred receptive field predicts the neural response as a function of responses elsewhere in the nervous system. When applied to two cortical regions, this function can be called the cortico-cortical receptive field (CCRF. We model the CCRF as a Gaussian-weighted region on the cortical surface and apply the model to data from both stimulus-driven and resting-state experimental conditions in visual cortex.

Speech recognition employing biologically plausible receptive fields

DEFF Research Database (Denmark)

Fereczkowski, Michal; Bothe, Hans-Heinrich

2011-01-01

spectro-temporal receptive fields to auditory spectrogram input, motivated by the auditory pathway of humans, and ii) the adaptation or learning algorithms involved are biologically inspired. This is in contrast to state-of-the-art combinations of Mel-frequency cepstral coefficients and Hidden Markov...

Natural image sequences constrain dynamic receptive fields and imply a sparse code.

Science.gov (United States)

Häusler, Chris; Susemihl, Alex; Nawrot, Martin P

2013-11-06

In their natural environment, animals experience a complex and dynamic visual scenery. Under such natural stimulus conditions, neurons in the visual cortex employ a spatially and temporally sparse code. For the input scenario of natural still images, previous work demonstrated that unsupervised feature learning combined with the constraint of sparse coding can predict physiologically measured receptive fields of simple cells in the primary visual cortex. This convincingly indicated that the mammalian visual system is adapted to the natural spatial input statistics. Here, we extend this approach to the time domain in order to predict dynamic receptive fields that can account for both spatial and temporal sparse activation in biological neurons. We rely on temporal restricted Boltzmann machines and suggest a novel temporal autoencoding training procedure. When tested on a dynamic multi-variate benchmark dataset this method outperformed existing models of this class. Learning features on a large dataset of natural movies allowed us to model spatio-temporal receptive fields for single neurons. They resemble temporally smooth transformations of previously obtained static receptive fields and are thus consistent with existing theories. A neuronal spike response model demonstrates how the dynamic receptive field facilitates temporal and population sparseness. We discuss the potential mechanisms and benefits of a spatially and temporally sparse representation of natural visual input. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

Contour detection based on nonclassical receptive field inhibition

NARCIS (Netherlands)

Grigorescu, Cosmin; Petkov, Nicolai; Westenberg, Michel A.

We propose a biologically motivated computational step, called nonclassical receptive field (non-CRF) inhibition, more generally surround inhibition or suppression, to improve contour detection in machine vision. Non-CRF inhibition is exhibited by 80% of the orientation-selective neurons in the

Does attention play a role in dynamic receptive field adaptation to changing acoustic salience in A1?

Science.gov (United States)

Fritz, Jonathan B; Elhilali, Mounya; David, Stephen V; Shamma, Shihab A

2007-07-01

Acoustic filter properties of A1 neurons can dynamically adapt to stimulus statistics, classical conditioning, instrumental learning and the changing auditory attentional focus. We have recently developed an experimental paradigm that allows us to view cortical receptive field plasticity on-line as the animal meets different behavioral challenges by attending to salient acoustic cues and changing its cortical filters to enhance performance. We propose that attention is the key trigger that initiates a cascade of events leading to the dynamic receptive field changes that we observe. In our paradigm, ferrets were initially trained, using conditioned avoidance training techniques, to discriminate between background noise stimuli (temporally orthogonal ripple combinations) and foreground tonal target stimuli. They learned to generalize the task for a wide variety of distinct background and foreground target stimuli. We recorded cortical activity in the awake behaving animal and computed on-line spectrotemporal receptive fields (STRFs) of single neurons in A1. We observed clear, predictable task-related changes in STRF shape while the animal performed spectral tasks (including single tone and multi-tone detection, and two-tone discrimination) with different tonal targets. A different set of task-related changes occurred when the animal performed temporal tasks (including gap detection and click-rate discrimination). Distinctive cortical STRF changes may constitute a "task-specific signature". These spectral and temporal changes in cortical filters occur quite rapidly, within 2min of task onset, and fade just as quickly after task completion, or in some cases, persisted for hours. The same cell could multiplex by differentially changing its receptive field in different task conditions. On-line dynamic task-related changes, as well as persistent plastic changes, were observed at a single-unit, multi-unit and population level. Auditory attention is likely to be pivotal in

Binocular neurons in parastriate cortex: interocular 'matching' of receptive field properties, eye dominance and strength of silent suppression.

Directory of Open Access Journals (Sweden)

Phillip A Romo

Full Text Available Spike-responses of single binocular neurons were recorded from a distinct part of primary visual cortex, the parastriate cortex (cytoarchitectonic area 18 of anaesthetized and immobilized domestic cats. Functional identification of neurons was based on the ratios of phase-variant (F1 component to the mean firing rate (F0 of their spike-responses to optimized (orientation, direction, spatial and temporal frequencies and size sine-wave-luminance-modulated drifting grating patches presented separately via each eye. In over 95% of neurons, the interocular differences in the phase-sensitivities (differences in F1/F0 spike-response ratios were small (≤ 0.3 and in over 80% of neurons, the interocular differences in preferred orientations were ≤ 10°. The interocular correlations of the direction selectivity indices and optimal spatial frequencies, like those of the phase sensitivies and optimal orientations, were also strong (coefficients of correlation r ≥ 0.7005. By contrast, the interocular correlations of the optimal temporal frequencies, the diameters of summation areas of the excitatory responses and suppression indices were weak (coefficients of correlation r ≤ 0.4585. In cells with high eye dominance indices (HEDI cells, the mean magnitudes of suppressions evoked by stimulation of silent, extra-classical receptive fields via the non-dominant eyes, were significantly greater than those when the stimuli were presented via the dominant eyes. We argue that the well documented 'eye-origin specific' segregation of the lateral geniculate inputs underpinning distinct eye dominance columns in primary visual cortices of mammals with frontally positioned eyes (distinct eye dominance columns, combined with significant interocular differences in the strength of silent suppressive fields, putatively contribute to binocular stereoscopic vision.

A Pixel-Encoder Retinal Ganglion Cell with Spatially Offset Excitatory and Inhibitory Receptive Fields

Directory of Open Access Journals (Sweden)

Keith P. Johnson

2018-02-01

Full Text Available The spike trains of retinal ganglion cells (RGCs are the only source of visual information to the brain. Here, we genetically identify an RGC type in mice that functions as a pixel encoder and increases firing to light increments (PixON-RGC. PixON-RGCs have medium-sized dendritic arbors and non-canonical center-surround receptive fields. From their receptive field center, PixON-RGCs receive only excitatory input, which encodes contrast and spatial information linearly. From their receptive field surround, PixON-RGCs receive only inhibitory input, which is temporally matched to the excitatory center input. As a result, the firing rate of PixON-RGCs linearly encodes local image contrast. Spatially offset (i.e., truly lateral inhibition of PixON-RGCs arises from spiking GABAergic amacrine cells. The receptive field organization of PixON-RGCs is independent of stimulus wavelength (i.e., achromatic. PixON-RGCs project predominantly to the dorsal lateral geniculate nucleus (dLGN of the thalamus and likely contribute to visual perception.

Structure of receptive fields in a computational model of area 3b of primary sensory cortex.

Science.gov (United States)

Detorakis, Georgios Is; Rougier, Nicolas P

2014-01-01

In a previous work, we introduced a computational model of area 3b which is built upon the neural field theory and receives input from a simplified model of the index distal finger pad populated by a random set of touch receptors (Merkell cells). This model has been shown to be able to self-organize following the random stimulation of the finger pad model and to cope, to some extent, with cortical or skin lesions. The main hypothesis of the model is that learning of skin representations occurs at the thalamo-cortical level while cortico-cortical connections serve a stereotyped competition mechanism that shapes the receptive fields. To further assess this hypothesis and the validity of the model, we reproduced in this article the exact experimental protocol of DiCarlo et al. that has been used to examine the structure of receptive fields in area 3b of the primary somatosensory cortex. Using the same analysis toolset, the model yields consistent results, having most of the receptive fields to contain a single region of excitation and one to several regions of inhibition. We further proceeded our study using a dynamic competition that deeply influences the formation of the receptive fields. We hypothesized this dynamic competition to correspond to some form of somatosensory attention that may help to precisely shape the receptive fields. To test this hypothesis, we designed a protocol where an arbitrary region of interest is delineated on the index distal finger pad and we either (1) instructed explicitly the model to attend to this region (simulating an attentional signal) (2) preferentially trained the model on this region or (3) combined the two aforementioned protocols simultaneously. Results tend to confirm that dynamic competition leads to shrunken receptive fields and its joint interaction with intensive training promotes a massive receptive fields migration and shrinkage.

Structure of Receptive Fields in a Computational Model of Area 3b of Primary Sensory Cortex

Directory of Open Access Journals (Sweden)

Georgios eDetorakis

2014-07-01

Full Text Available In a previous work, we introduced a computational model of area 3b which is built upon the neural field theory and receives input from a simplified model of the index distal finger pad populated by a random set of touch receptors(Merkell cells. This model has been shown to be able to self-organize following the random stimulation of the finger pad model and to cope, to some extent, with cortical or skin lesions. The main hypothesis of the model is that learning of skin representations occurs at the thalamo-cortical level while cortico-cortical connections serve a stereotyped competition mechanism that shapes the receptive fields. To further assess this hypothesis and the validity of the model, we reproduced in this article the exact experimental protocol of DiCarlo et al. that has been used to examine the structure of receptive fields in area 3b of the primary somatosensory cortex. Using the same analysis toolset, the model yields consistent results, having most of the receptive fields to contain a single region of excitation and one to severalregions of inhibition. We further proceeded our study using a dynamic competition that deeply influences the formation of the receptive fields. We hypothesized this dynamic competition to correspond to some form of somatosensory attention that may help to precisely shape the receptive fields. To test this hypothesis, we designed a protocol where an arbitrary region of interest is delineated on the index distal finger pad and we either (1 instructed explicitly the model to attend to this region (simulating an attentional signal (2 preferentially trained the model on this region or (3combined the two aforementioned protocols simultaneously. Results tend to confirm that dynamic competition leads to shrunken receptive fields and its joint interaction with intensive training promotes a massive receptive fields migration and shrinkage.

Classical field theory

CERN Document Server

Franklin, Joel

2017-01-01

Classical field theory, which concerns the generation and interaction of fields, is a logical precursor to quantum field theory, and can be used to describe phenomena such as gravity and electromagnetism. Written for advanced undergraduates, and appropriate for graduate level classes, this book provides a comprehensive introduction to field theories, with a focus on their relativistic structural elements. Such structural notions enable a deeper understanding of Maxwell's equations, which lie at the heart of electromagnetism, and can also be applied to modern variants such as Chern–Simons and Born–Infeld. The structure of field theories and their physical predictions are illustrated with compelling examples, making this book perfect as a text in a dedicated field theory course, for self-study, or as a reference for those interested in classical field theory, advanced electromagnetism, or general relativity. Demonstrating a modern approach to model building, this text is also ideal for students of theoretic...

Attention directed by expectations enhances receptive fields in cortical area MT.

Science.gov (United States)

Ghose, Geoffrey M; Bearl, David W

2010-02-22

Expectations, especially those formed on the basis of extensive training, can substantially enhance visual performance. However, it is not clear that the physiological mechanisms underlying this enhancement are identical to those examined by experiments in which attention is directed by explicit instructions rather than strong expectations. To study the changes in visual representations associated with strong expectations, we trained animals to detect a brief motion pulse that was embedded in noise. Because the nature of the pulse and the statistics of its appearance were well known to the animals, they formed strong expectations which determined their behavioral performance. We used white-noise methods to infer the receptive field structure of single neurons in area MT while they were performing this task. Incorporating non-linearities, we compared receptive fields during periods of time when the animals were expecting the motion pulse with periods of time when they were not. We found receptive field changes consistent with an increased reliability in signaling pulse occurrence. Moreover, these changes were not consistent with a simple gain modulation. The results suggest that strong expectations can create very specific changes in the visual representations at a cellular level to enhance performance. Copyright 2009 Elsevier Ltd. All rights reserved.

Classical field approach to quantum weak measurements.

Science.gov (United States)

Dressel, Justin; Bliokh, Konstantin Y; Nori, Franco

2014-03-21

By generalizing the quantum weak measurement protocol to the case of quantum fields, we show that weak measurements probe an effective classical background field that describes the average field configuration in the spacetime region between pre- and postselection boundary conditions. The classical field is itself a weak value of the corresponding quantum field operator and satisfies equations of motion that extremize an effective action. Weak measurements perturb this effective action, producing measurable changes to the classical field dynamics. As such, weakly measured effects always correspond to an effective classical field. This general result explains why these effects appear to be robust for pre- and postselected ensembles, and why they can also be measured using classical field techniques that are not weak for individual excitations of the field.

Nonredundant sparse feature extraction using autoencoders with receptive fields clustering.

Science.gov (United States)

Ayinde, Babajide O; Zurada, Jacek M

2017-09-01

This paper proposes new techniques for data representation in the context of deep learning using agglomerative clustering. Existing autoencoder-based data representation techniques tend to produce a number of encoding and decoding receptive fields of layered autoencoders that are duplicative, thereby leading to extraction of similar features, thus resulting in filtering redundancy. We propose a way to address this problem and show that such redundancy can be eliminated. This yields smaller networks and produces unique receptive fields that extract distinct features. It is also shown that autoencoders with nonnegativity constraints on weights are capable of extracting fewer redundant features than conventional sparse autoencoders. The concept is illustrated using conventional sparse autoencoder and nonnegativity-constrained autoencoders with MNIST digits recognition, NORB normalized-uniform object data and Yale face dataset. Copyright © 2017 Elsevier Ltd. All rights reserved.

Population receptive field (pRF) measurements of chromatic responses in human visual cortex using fMRI.

Science.gov (United States)

Welbourne, Lauren E; Morland, Antony B; Wade, Alex R

2018-02-15

The spatial sensitivity of the human visual system depends on stimulus color: achromatic gratings can be resolved at relatively high spatial frequencies while sensitivity to isoluminant color contrast tends to be more low-pass. Models of early spatial vision often assume that the receptive field size of pattern-sensitive neurons is correlated with their spatial frequency sensitivity - larger receptive fields are typically associated with lower optimal spatial frequency. A strong prediction of this model is that neurons coding isoluminant chromatic patterns should have, on average, a larger receptive field size than neurons sensitive to achromatic patterns. Here, we test this assumption using functional magnetic resonance imaging (fMRI). We show that while spatial frequency sensitivity depends on chromaticity in the manner predicted by behavioral measurements, population receptive field (pRF) size measurements show no such dependency. At any given eccentricity, the mean pRF size for neuronal populations driven by luminance, opponent red/green and S-cone isolating contrast, are identical. Changes in pRF size (for example, an increase with eccentricity and visual area hierarchy) are also identical across the three chromatic conditions. These results suggest that fMRI measurements of receptive field size and spatial resolution can be decoupled under some circumstances - potentially reflecting a fundamental dissociation between these parameters at the level of neuronal populations. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Discriminative learning of receptive fields from responses to non-Gaussian stimulus ensembles.

Science.gov (United States)

Meyer, Arne F; Diepenbrock, Jan-Philipp; Happel, Max F K; Ohl, Frank W; Anemüller, Jörn

2014-01-01

Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF) estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa) is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF) estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA) do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to natural stimuli and

Discriminative learning of receptive fields from responses to non-Gaussian stimulus ensembles.

Directory of Open Access Journals (Sweden)

Arne F Meyer

Full Text Available Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to

More Gamma More Predictions: Gamma-Synchronization as a Key Mechanism for Efficient Integration of Classical Receptive Field Inputs with Surround Predictions

Science.gov (United States)

Vinck, Martin; Bosman, Conrado A.

2016-01-01

During visual stimulation, neurons in visual cortex often exhibit rhythmic and synchronous firing in the gamma-frequency (30–90 Hz) band. Whether this phenomenon plays a functional role during visual processing is not fully clear and remains heavily debated. In this article, we explore the function of gamma-synchronization in the context of predictive and efficient coding theories. These theories hold that sensory neurons utilize the statistical regularities in the natural world in order to improve the efficiency of the neural code, and to optimize the inference of the stimulus causes of the sensory data. In visual cortex, this relies on the integration of classical receptive field (CRF) data with predictions from the surround. Here we outline two main hypotheses about gamma-synchronization in visual cortex. First, we hypothesize that the precision of gamma-synchronization reflects the extent to which CRF data can be accurately predicted by the surround. Second, we hypothesize that different cortical columns synchronize to the extent that they accurately predict each other’s CRF visual input. We argue that these two hypotheses can account for a large number of empirical observations made on the stimulus dependencies of gamma-synchronization. Furthermore, we show that they are consistent with the known laminar dependencies of gamma-synchronization and the spatial profile of intercolumnar gamma-synchronization, as well as the dependence of gamma-synchronization on experience and development. Based on our two main hypotheses, we outline two additional hypotheses. First, we hypothesize that the precision of gamma-synchronization shows, in general, a negative dependence on RF size. In support, we review evidence showing that gamma-synchronization decreases in strength along the visual hierarchy, and tends to be more prominent in species with small V1 RFs. Second, we hypothesize that gamma-synchronized network dynamics facilitate the emergence of spiking output that

The classical theory of fields electromagnetism

CERN Document Server

Helrich, Carl S

2012-01-01

The study of classical electromagnetic fields is an adventure. The theory is complete mathematically and we are able to present it as an example of classical Newtonian experimental and mathematical philosophy. There is a set of foundational experiments, on which most of the theory is constructed. And then there is the bold theoretical proposal of a field-field interaction from James Clerk Maxwell. This textbook presents the theory of classical fields as a mathematical structure based solidly on laboratory experiments. Here the student is introduced to the beauty of classical field theory as a gem of theoretical physics. To keep the discussion fluid, the history is placed in a beginning chapter and some of the mathematical proofs in the appendices. Chapters on Green’s Functions and Laplace’s Equation and a discussion of Faraday’s Experiment further deepen the understanding. The chapter on Einstein’s relativity is an integral necessity to the text. Finally, chapters on particle motion and waves in a dis...

Spatiotemporal profiles of receptive fields of neurons in the lateral posterior nucleus of the cat LP-pulvinar complex.

Science.gov (United States)

Piché, Marilyse; Thomas, Sébastien; Casanova, Christian

2015-10-01

The pulvinar is the largest extrageniculate thalamic visual nucleus in mammals. It establishes reciprocal connections with virtually all visual cortexes and likely plays a role in transthalamic cortico-cortical communication. In cats, the lateral posterior nucleus (LP) of the LP-pulvinar complex can be subdivided in two subregions, the lateral (LPl) and medial (LPm) parts, which receive a predominant input from the striate cortex and the superior colliculus, respectively. Here, we revisit the receptive field structure of LPl and LPm cells in anesthetized cats by determining their first-order spatiotemporal profiles through reverse correlation analysis following sparse noise stimulation. Our data reveal the existence of previously unidentified receptive field profiles in the LP nucleus both in space and time domains. While some cells responded to only one stimulus polarity, the majority of neurons had receptive fields comprised of bright and dark responsive subfields. For these neurons, dark subfields' size was larger than that of bright subfields. A variety of receptive field spatial organization types were identified, ranging from totally overlapped to segregated bright and dark subfields. In the time domain, a large spectrum of activity overlap was found, from cells with temporally coinciding subfield activity to neurons with distinct, time-dissociated subfield peak activity windows. We also found LP neurons with space-time inseparable receptive fields and neurons with multiple activity periods. Finally, a substantial degree of homology was found between LPl and LPm first-order receptive field spatiotemporal profiles, suggesting a high integration of cortical and subcortical inputs within the LP-pulvinar complex. Copyright © 2015 the American Physiological Society.

Two-dimensional receptive-field organization in striate cortical neurons of the cat.

Science.gov (United States)

Sun, M; Bonds, A B

1994-01-01

The two-dimensional organization of receptive fields (RFs) of 44 cells in the cat visual cortex and four cells from the cat LGN was measured by stimulation with either dots or bars of light. The light bars were presented in different positions and orientations centered on the RFs. The RFs found were arbitrarily divided into four general types: Punctate, resembling DOG filters (11%); those resembling Gabor filters (9%); elongate (36%); and multipeaked-type (44%). Elongate RFs, usually found in simple cells, could show more than one excitatory band or bifurcation of excitatory regions. Although regions inhibitory to a given stimulus transition (e.g. ON) often coincided with regions excitatory to the opposite transition (e.g. OFF), this was by no means the rule. Measurements were highly repeatable and stable over periods of at least 1 h. A comparison between measurements made with dots and with bars showed reasonable matches in about 40% of the cases. In general, bar-based measurements revealed larger RFs with more structure, especially with respect to inhibitory regions. Inactivation of lower cortical layers (V-VI) by local GABA injection was found to reduce sharpness of detail and to increase both receptive-field size and noise in upper layer cells, suggesting vertically organized RF mechanisms. Across the population, some cells bore close resemblance to theoretically proposed filters, while others had a complexity that was clearly not generalizable, to the extent that they seemed more suited to detection of specific structures. We would speculate that the broadly varying forms of cat cortical receptive fields result from developmental processes akin to those that form ocular-dominance columns, but on a smaller scale.

The spin-statistics connection in classical field theory

International Nuclear Information System (INIS)

Morgan, J A

2006-01-01

The spin-statistics connection is obtained for a simple formulation of a classical field theory containing even and odd Grassmann variables. To that end, the construction of irreducible canonical realizations of the rotation group corresponding to general causal fields is reviewed. The connection is obtained by imposing local commutativity on the fields and exploiting the parity operation to exchange spatial coordinates in the scalar product of classical field evaluated at one spatial location with the same field evaluated at a distinct location. The spin-statistics connection for irreducible canonical realizations of the Poincare group of spin j is obtained in the form: classical fields and their conjugate momenta satisfy fundamental field-theoretic Poisson bracket relations for 2j even and fundamental Poisson antibracket relations for 2j odd

Prequantum classical statistical field theory: background field as a source of everything?

International Nuclear Information System (INIS)

Khrennikov, Andrei

2011-01-01

Prequantum classical statistical field theory (PCSFT) is a new attempt to consider quantum mechanics (QM) as an emergent phenomenon, cf. with De Broglie's 'double solution' approach, Bohmian mechanics, stochastic electrodynamics (SED), Nelson's stochastic QM and its generalization by Davidson, 't Hooft's models and their development by Elze. PCSFT is a comeback to a purely wave viewpoint on QM, cf. with early Schrodinger. There is no quantum particles at all, only waves. In particular, photons are simply wave-pulses of the classical electromagnetic field, cf. SED. Moreover, even massive particles are special 'prequantum fields': the electron field, the neutron field, and so on. PCSFT claims that (sooner or later) people will be able to measure components of these fields: components of the 'photonic field' (the classical electromagnetic field of low intensity), electronic field, neutronic field, and so on. At the moment we are able to produce quantum correlations as correlations of classical Gaussian random fields. In this paper we are interested in mathematical and physical reasons of usage of Gaussian fields. We consider prequantum signals (corresponding to quantum systems) as composed of a huge number of wave-pulses (on very fine prequantum time scale). We speculate that the prequantum background field (the field of 'vacuum fluctuations') might play the role of a source of such pulses, i.e., the source of everything.

MOBIUS-STRIP-LIKE COLUMNAR FUNCTIONAL CONNECTIONS ARE REVEALED IN SOMATO-SENSORY RECEPTIVE FIELD CENTROIDS.

Directory of Open Access Journals (Sweden)

James Joseph Wright

2014-10-01

Full Text Available Receptive fields of neurons in the forelimb region of areas 3b and 1 of primary somatosensory cortex, in cats and monkeys, were mapped using extracellular recordings obtained sequentially from nearly radial penetrations. Locations of the field centroids indicated the presence of a functional system, in which cortical homotypic representations of the limb surfaces are entwined in three-dimensional Mobius-strip-like patterns of synaptic connections. Boundaries of somatosensory receptive field in nested groups irregularly overlie the centroid order, and are interpreted as arising from the superposition of learned connections upon the embryonic order. Since the theory of embryonic synaptic self-organisation used to model these results was devised and earlier used to explain findings in primary visual cortex, the present findings suggest the theory may be of general application throughout cortex, and may reveal a modular functional synaptic system, which, only in some parts of the cortex, and in some species, is manifest as anatomical ordering into columns.

Enhancing Quantum Discord in Cavity QED by Applying Classical Driving Field

International Nuclear Information System (INIS)

Qian Yi; Xu Jing-Bo

2012-01-01

We investigate the quantum discord dynamics in a cavity quantum electrodynamics system, which consists of two noninteracting two-level atoms driven by independent optical fields and classical fields, and find that the quantum discord vanishes only asymptotically although entanglement disappears suddenly during the time evolution in the absence of classical fields. It is shown that the amount of quantum discord can be increased by adjusting the classical driving fields because the increasing degree of the amount of quantum mutual information is greater than classical correlation by applying the classical driving fields. Finally, the influence of the classical driving field on the fidelity of the system is also examined. (general)

Lectures on classical and quantum theory of fields

International Nuclear Information System (INIS)

Arodz, Henryk; Hadasz, Leszek

2010-01-01

This textbook on classical and quantum theory of fields addresses graduate students starting to specialize in theoretical physics. It provides didactic introductions to the main topics in the theory of fields, while taking into account the contemporary view of the subject. The student will find concise explanations of basic notions essential for applications of the theory of fields as well as for frontier research in theoretical physics. One third of the book is devoted to classical fields. Each chapter contains exercises of varying degree of difficulty with hints or solutions, plus summaries and worked examples as useful. The textbook is based on lectures delivered to students of theoretical physics at Jagiellonian University. It aims to deliver a unique combination of classical and quantum field theory in one compact course. (orig.)

Lectures on Classical and Quantum Theory of Fields

CERN Document Server

Arodź, Henryk

2010-01-01

This textbook on classical and quantum theory of fields addresses graduate students starting to specialize in theoretical physics. It provides didactic introductions to the main topics in the theory of fields, while taking into account the contemporary view of the subject. The student will find concise explanations of basic notions essential for applications of the theory of fields as well as for frontier research in theoretical physics. One third of the book is devoted to classical fields. Each chapter contains exercises of varying degree of difficulty with hints or solutions, plus summaries and worked examples as useful. The textbook is based on lectures delivered to students of theoretical physics at Jagiellonian University. It aims to deliver a unique combination of classical and quantum field theory in one compact course.

Lectures on classical and quantum theory of fields

Energy Technology Data Exchange (ETDEWEB)

Arodz, Henryk; Hadasz, Leszek [Jagiellonian Univ., Krakow (Poland). Inst. Physics

2010-07-01

This textbook on classical and quantum theory of fields addresses graduate students starting to specialize in theoretical physics. It provides didactic introductions to the main topics in the theory of fields, while taking into account the contemporary view of the subject. The student will find concise explanations of basic notions essential for applications of the theory of fields as well as for frontier research in theoretical physics. One third of the book is devoted to classical fields. Each chapter contains exercises of varying degree of difficulty with hints or solutions, plus summaries and worked examples as useful. The textbook is based on lectures delivered to students of theoretical physics at Jagiellonian University. It aims to deliver a unique combination of classical and quantum field theory in one compact course. (orig.)

Cortical depth dependent population receptive field attraction by spatial attention in human V1

NARCIS (Netherlands)

Klein, Barrie P.; Fracasso, Alessio; van Dijk, Jelle A.; Paffen, Chris L.E.; te Pas, Susan F.; Dumoulin, Serge O.

2018-01-01

Visual spatial attention concentrates neural resources at the attended location. Recently, we demonstrated that voluntary spatial attention attracts population receptive fields (pRFs) toward its location throughout the visual hierarchy. Theoretically, both a feed forward or feedback mechanism could

Exploring extra dimensions with scalar fields

Science.gov (United States)

Brown, Katherine; Mathur, Harsh; Verostek, Mike

2018-05-01

This paper provides a pedagogical introduction to the physics of extra dimensions by examining the behavior of scalar fields in three landmark models: the ADD, Randall-Sundrum, and DGP spacetimes. Results of this analysis provide qualitative insights into the corresponding behavior of gravitational fields and elementary particles in each of these models. In these "brane world" models, the familiar four dimensional spacetime of everyday experience is called the brane and is a slice through a higher dimensional spacetime called the bulk. The particles and fields of the standard model are assumed to be confined to the brane, while gravitational fields are assumed to propagate in the bulk. For all three spacetimes, we calculate the spectrum of propagating scalar wave modes and the scalar field produced by a static point source located on the brane. For the ADD and Randall-Sundrum models, at large distances, the field looks like that of a point source in four spacetime dimensions, but at short distances, it crosses over to a form appropriate to the higher dimensional spacetime. For the DGP model, the field has the higher dimensional form at long distances rather than short. The behavior of these scalar fields, derived using only undergraduate level mathematics, closely mirror the results that one would obtain by performing the far more difficult task of analyzing the behavior of gravitational fields in these spacetimes.

Classical theory of electric and magnetic fields

CERN Document Server

Good, Roland H

1971-01-01

Classical Theory of Electric and Magnetic Fields is a textbook on the principles of electricity and magnetism. This book discusses mathematical techniques, calculations, with examples of physical reasoning, that are generally applied in theoretical physics. This text reviews the classical theory of electric and magnetic fields, Maxwell's Equations, Lorentz Force, and Faraday's Law of Induction. The book also focuses on electrostatics and the general methods for solving electrostatic problems concerning images, inversion, complex variable, or separation of variables. The text also explains ma

Callosal Influence on Visual Receptive Fields Has an Ocular, an Orientation-and Direction Bias

Directory of Open Access Journals (Sweden)

Sergio A. Conde-Ocazionez

2018-04-01

Full Text Available One leading hypothesis on the nature of visual callosal connections (CC is that they replicate features of intrahemispheric lateral connections. However, CC act also in the central part of the binocular visual field. In agreement, early experiments in cats indicated that they provide the ipsilateral eye part of binocular receptive fields (RFs at the vertical midline (Berlucchi and Rizzolatti, 1968, and play a key role in stereoscopic function. But until today callosal inputs to receptive fields activated by one or both eyes were never compared simultaneously, because callosal function has been often studied by cutting or lesioning either corpus callosum or optic chiasm not allowing such a comparison. To investigate the functional contribution of CC in the intact cat visual system we recorded both monocular and binocular neuronal spiking responses and receptive fields in the 17/18 transition zone during reversible deactivation of the contralateral hemisphere. Unexpectedly from many of the previous reports, we observe no change in ocular dominance during CC deactivation. Throughout the transition zone, a majority of RFs shrink, but several also increase in size. RFs are significantly more affected for ipsi- as opposed to contralateral stimulation, but changes are also observed with binocular stimulation. Noteworthy, RF shrinkages are tiny and not correlated to the profound decreases of monocular and binocular firing rates. They depend more on orientation and direction preference than on eccentricity or ocular dominance of the receiving neuron's RF. Our findings confirm that in binocularly viewing mammals, binocular RFs near the midline are constructed via the direct geniculo-cortical pathway. They also support the idea that input from the two eyes complement each other through CC: Rather than linking parts of RFs separated by the vertical meridian, CC convey a modulatory influence, reflecting the feature selectivity of lateral circuits, with a

A self-organizing model of perisaccadic visual receptive field dynamics in primate visual and oculomotor system.

Science.gov (United States)

Mender, Bedeho M W; Stringer, Simon M

2015-01-01

We propose and examine a model for how perisaccadic visual receptive field dynamics, observed in a range of primate brain areas such as LIP, FEF, SC, V3, V3A, V2, and V1, may develop through a biologically plausible process of unsupervised visually guided learning. These dynamics are associated with remapping, which is the phenomenon where receptive fields anticipate the consequences of saccadic eye movements. We find that a neural network model using a local associative synaptic learning rule, when exposed to visual scenes in conjunction with saccades, can account for a range of associated phenomena. In particular, our model demonstrates predictive and pre-saccadic remapping, responsiveness shifts around the time of saccades, and remapping from multiple directions.

Effect of Using Extra Fins on the Pin Fin Classic Geometry for Enhancement Heat Sink Performance using EGM Method

Directory of Open Access Journals (Sweden)

Kadhum Audaa Jehhef

2018-04-01

Full Text Available In the present study, the effect of new cross-section fin geometries on overall thermal/fluid performance had been investigated. The cross-section included the base original geometry of (triangular, square, circular, and elliptical pin fins by adding exterior extra fins along the sides of the origin fins. The present extra fins include rectangular extra fin of 2 mm (height and 4 mm (width and triangular extra fin of 2 mm (base 4 mm (height. The use of entropy generation minimization method (EGM allows the combined effect of thermal resistance and pressure drop to be assessed through the simultaneous interaction with the heat sink. A general dimensionless expression for the entropy generation rate is obtained by considering a control volume around the pin fin including a base plate and applying the conservations equations of mass and energy with the entropy balance. The dimensionless numbers used includes the aspect ratio (ε, Reynolds number (Re, Nusselt number (Nu, and the drag coefficients (CD. Fourteen different cross-section fin geometries are examined for the heat transfer, fluid friction, and the minimum entropy generation rate. The results showed that the Nusselt number increases with increasing the Reynolds number for all employed models. The ellipse models (ET and ER-models give the highest value in the Nusselt number as compared with the classical pin fins. The fin of the square geometry with four rectangular extra fins (SR-models gives an agreement in Nusselt number as compared with the previous study.

The thalamo-cortical auditory receptive fields: regulation by the states of vigilance, learning and the neuromodulatory systems.

Science.gov (United States)

Edeline, Jean-Marc

2003-12-01

The goal of this review is twofold. First, it aims to describe the dynamic regulation that constantly shapes the receptive fields (RFs) and maps in the thalamo-cortical sensory systems of undrugged animals. Second, it aims to discuss several important issues that remain unresolved at the intersection between behavioral neurosciences and sensory physiology. A first section presents the RF modulations observed when an undrugged animal spontaneously shifts from waking to slow-wave sleep or to paradoxical sleep (also called REM sleep). A second section shows that, in contrast with the general changes described in the first section, behavioral training can induce selective effects which favor the stimulus that has acquired significance during learning. A third section reviews the effects triggered by two major neuromodulators of the thalamo-cortical system--acetylcholine and noradrenaline--which are traditionally involved both in the switch of vigilance states and in learning experiences. The conclusion argues that because the receptive fields and maps of an awake animal are continuously modulated from minute to minute, learning-induced sensory plasticity can be viewed as a "crystallization" of the receptive fields and maps in one of the multiple possible states. Studying the interplays between neuromodulators can help understanding the neurobiological foundations of this dynamic regulation.

Dynamics of classical and quantum fields an introduction

CERN Document Server

Setlur, Girish S

2014-01-01

Dynamics of Classical and Quantum Fields: An Introduction focuses on dynamical fields in non-relativistic physics. Written by a physicist for physicists, the book is designed to help readers develop analytical skills related to classical and quantum fields at the non-relativistic level, and think about the concepts and theory through numerous problems. In-depth yet accessible, the book presents new and conventional topics in a self-contained manner that beginners would find useful. A partial list of topics covered includes: Geometrical meaning of Legendre transformation in classical mechanics Dynamical symmetries in the context of Noether's theorem The derivation of the stress energy tensor of the electromagnetic field, the expression for strain energy in elastic bodies, and the Navier Stokes equation Concepts of right and left movers in case of a Fermi gas explained Functional integration is interpreted as a limit of a sequence of ordinary integrations Path integrals for one and two quantum particles and for...

k-Cosymplectic Classical Field Theories: Tulczyjew and Skinner-Rusk Formulations

Science.gov (United States)

Rey, Angel M.; Román-Roy, Narciso; Salgado, Modesto; Vilariño, Silvia

2012-06-01

The k-cosymplectic Lagrangian and Hamiltonian formalisms of first-order classical field theories are reviewed and completed. In particular, they are stated for singular and almost-regular systems. Subsequently, several alternative formulations for k-cosymplectic first-order field theories are developed: First, generalizing the construction of Tulczyjew for mechanics, we give a new interpretation of the classical field equations. Second, the Lagrangian and Hamiltonian formalisms are unified by giving an extension of the Skinner-Rusk formulation on classical mechanics.

k-Cosymplectic Classical Field Theories: Tulczyjew and Skinner–Rusk Formulations

International Nuclear Information System (INIS)

Rey, Angel M.; Román-Roy, Narciso; Salgado, Modesto; Vilariño, Silvia

2012-01-01

The k-cosymplectic Lagrangian and Hamiltonian formalisms of first-order classical field theories are reviewed and completed. In particular, they are stated for singular and almost-regular systems. Subsequently, several alternative formulations for k-cosymplectic first-order field theories are developed: First, generalizing the construction of Tulczyjew for mechanics, we give a new interpretation of the classical field equations. Second, the Lagrangian and Hamiltonian formalisms are unified by giving an extension of the Skinner–Rusk formulation on classical mechanics.

An analogue of the Heisenberg uncertainty relation in prequantum classical field theory

Energy Technology Data Exchange (ETDEWEB)

Khrennikov, Andrei, E-mail: Andrei.Khrennikov@vxu.s [International Center for Mathematical Modelling in Physics and Cognitive Sciences, University of Vaexjoe, Vaexjoe (Sweden) and Institute of Information Security, Russian State University for Humanities, Moscow (Russian Federation)

2010-02-01

Prequantum classical statistical field theory (PCSFT) is a model that provides the possibility of representing averages of quantum observables, including correlations of observables on subsystems of a composite system, as averages with respect to fluctuations of classical random fields. PCSFT is a classical model of wave type. For example, 'electron' is described by electronic field. In contrast to quantum mechanics (QM), this field is a real physical field and not a field of probabilities. An important point is that the prequantum field of , for example, an electron contains the irreducible contribution of the background field vacuum fluctuations. In principle, the traditional QM-formalism can be considered as a special regularization procedure: subtraction of averages with respect to vacuum fluctuations. In this paper, we derive a classical analogue of the Heisenberg-Robertson inequality for dispersions of functionals of classical (prequantum) fields. The PCSFT Robertson-like inequality provides a restriction on the product of classical dispersions. However, this restriction is not so rigid as in QM.

An analogue of the Heisenberg uncertainty relation in prequantum classical field theory

International Nuclear Information System (INIS)

Khrennikov, Andrei

2010-01-01

Prequantum classical statistical field theory (PCSFT) is a model that provides the possibility of representing averages of quantum observables, including correlations of observables on subsystems of a composite system, as averages with respect to fluctuations of classical random fields. PCSFT is a classical model of wave type. For example, 'electron' is described by electronic field. In contrast to quantum mechanics (QM), this field is a real physical field and not a field of probabilities. An important point is that the prequantum field of , for example, an electron contains the irreducible contribution of the background field vacuum fluctuations. In principle, the traditional QM-formalism can be considered as a special regularization procedure: subtraction of averages with respect to vacuum fluctuations. In this paper, we derive a classical analogue of the Heisenberg-Robertson inequality for dispersions of functionals of classical (prequantum) fields. The PCSFT Robertson-like inequality provides a restriction on the product of classical dispersions. However, this restriction is not so rigid as in QM.

Lectures on classical and quantum theory of fields

CERN Document Server

Arodz, Henryk

2017-01-01

This textbook addresses graduate students starting to specialize in theoretical physics. It provides didactic introductions to the main topics in the theory of fields, while taking into account the contemporary view of the subject. The student will find concise explanations of basic notions essential for applications of the theory of fields as well as for frontier research in theoretical physics. One third of the book is devoted to classical fields. Each chapter contains exercises of varying degree of difficulty with hints or solutions, plus summaries and worked examples as useful. It aims to deliver a unique combination of classical and quantum field theory in one compact course.

Effects of wind turbines on UHF television reception: field tests in Denmark

International Nuclear Information System (INIS)

Sorenson, B.

1992-01-01

As a result of a planning application for a windfarm comprising 20 wind turbines at Tynewydd Farm, Gilfach Goch in Mid Glamorgan, a report discussing any detrimental effects the proposal might have on u.h.f. television reception was produced. In order to make the report as definitive as possible, it was decided to carry out field tests on the exact model of wind turbine to be used at Tynewydd. This required a field trip to Denmark, and the opportunity was taken to make measurements on two other models of turbine at the same time. This report presents the analysis of the results for all three turbines. (author)

Quantum scattering from classical field theory

International Nuclear Information System (INIS)

Gould, T.M.; Poppitz, E.R.

1995-01-01

We show that scattering amplitudes between initial wave packet states and certain coherent final states can be computed in a systematic weak coupling expansion about classical solutions satisfying initial-value conditions. The initial-value conditions are such as to make the solution of the classical field equations amenable to numerical methods. We propose a practical procedure for computing classical solutions which contribute to high energy two-particle scattering amplitudes. We consider in this regard the implications of a recent numerical simulation in classical SU(2) Yang-Mills theory for multiparticle scattering in quantum gauge theories and speculate on its generalization to electroweak theory. We also generalize our results to the case of complex trajectories and discuss the prospects for finding a solution to the resulting complex boundary value problem, which would allow the application of our method to any wave packet to coherent state transition. Finally, we discuss the relevance of these results to the issues of baryon number violation and multiparticle scattering at high energies. ((orig.))

Chromatic summation and receptive field properties of blue-on and blue-off cells in marmoset lateral geniculate nucleus.

Science.gov (United States)

Eiber, C D; Pietersen, A N J; Zeater, N; Solomon, S G; Martin, P R

2017-11-22

The "blue-on" and "blue-off" receptive fields in retina and dorsal lateral geniculate nucleus (LGN) of diurnal primates combine signals from short-wavelength sensitive (S) cone photoreceptors with signals from medium/long wavelength sensitive (ML) photoreceptors. Three questions about this combination remain unresolved. Firstly, is the combination of S and ML signals in these cells linear or non-linear? Secondly, how does the timing of S and ML inputs to these cells influence their responses? Thirdly, is there spatial antagonism within S and ML subunits of the receptive field of these cells? We measured contrast sensitivity and spatial frequency tuning for four types of drifting sine gratings: S cone isolating, ML cone isolating, achromatic (S + ML), and counterphase chromatic (S - ML), in extracellular recordings from LGN of marmoset monkeys. We found that responses to stimuli which modulate both S and ML cones are well predicted by a linear sum of S and ML signals, followed by a saturating contrast-response relation. Differences in sensitivity and timing (i.e. vector combination) between S and ML inputs are needed to explain the amplitude and phase of responses to achromatic (S + ML) and counterphase chromatic (S - ML) stimuli. Best-fit spatial receptive fields for S and/or ML subunits in most cells (>80%) required antagonistic surrounds, usually in the S subunit. The surrounds were however generally weak and had little influence on spatial tuning. The sensitivity and size of S and ML subunits were correlated on a cell-by-cell basis, adding to evidence that blue-on and blue-off receptive fields are specialised to signal chromatic but not spatial contrast. Copyright © 2017 Elsevier Ltd. All rights reserved.

Classical and quantum electrodynamics and the B(3) field

CERN Document Server

Evans, Myron W

2001-01-01

It is well known that classical electrodynamics is riddled with internal inconsistencies springing from the fact that it is a linear, Abelian theory in which the potentials are unphysical. This volume offers a self-consistent hypothesis which removes some of these problems, as well as builds a framework on which linear and nonlinear optics are treated as a non-Abelian gauge field theory based on the emergence of the fundamental magnetizing field of radiation, the B(3) field. Contents: Interaction of Electromagnetic Radiation with One Fermion; The Field Equations of Classical O (3) b Electrodyn

Active listening: task-dependent plasticity of spectrotemporal receptive fields in primary auditory cortex.

Science.gov (United States)

Fritz, Jonathan; Elhilali, Mounya; Shamma, Shihab

2005-08-01

Listening is an active process in which attentive focus on salient acoustic features in auditory tasks can influence receptive field properties of cortical neurons. Recent studies showing rapid task-related changes in neuronal spectrotemporal receptive fields (STRFs) in primary auditory cortex of the behaving ferret are reviewed in the context of current research on cortical plasticity. Ferrets were trained on spectral tasks, including tone detection and two-tone discrimination, and on temporal tasks, including gap detection and click-rate discrimination. STRF changes could be measured on-line during task performance and occurred within minutes of task onset. During spectral tasks, there were specific spectral changes (enhanced response to tonal target frequency in tone detection and discrimination, suppressed response to tonal reference frequency in tone discrimination). However, only in the temporal tasks, the STRF was changed along the temporal dimension by sharpening temporal dynamics. In ferrets trained on multiple tasks, distinctive and task-specific STRF changes could be observed in the same cortical neurons in successive behavioral sessions. These results suggest that rapid task-related plasticity is an ongoing process that occurs at a network and single unit level as the animal switches between different tasks and dynamically adapts cortical STRFs in response to changing acoustic demands.

Quantum fermions and quantum field theory from classical statistics

International Nuclear Information System (INIS)

Wetterich, Christof

2012-01-01

An Ising-type classical statistical ensemble can describe the quantum physics of fermions if one chooses a particular law for the time evolution of the probability distribution. It accounts for the time evolution of a quantum field theory for Dirac particles in an external electromagnetic field. This yields in the non-relativistic one-particle limit the Schrödinger equation for a quantum particle in a potential. Interference or tunneling arise from classical probabilities.

A robust sub-pixel edge detection method of infrared image based on tremor-based retinal receptive field model

Science.gov (United States)

Gao, Kun; Yang, Hu; Chen, Xiaomei; Ni, Guoqiang

2008-03-01

Because of complex thermal objects in an infrared image, the prevalent image edge detection operators are often suitable for a certain scene and extract too wide edges sometimes. From a biological point of view, the image edge detection operators work reliably when assuming a convolution-based receptive field architecture. A DoG (Difference-of- Gaussians) model filter based on ON-center retinal ganglion cell receptive field architecture with artificial eye tremors introduced is proposed for the image contour detection. Aiming at the blurred edges of an infrared image, the subsequent orthogonal polynomial interpolation and sub-pixel level edge detection in rough edge pixel neighborhood is adopted to locate the foregoing rough edges in sub-pixel level. Numerical simulations show that this method can locate the target edge accurately and robustly.

Scattering of classical and quantum particles by impulsive fields

Science.gov (United States)

Balasin, Herbert; Aichelburg, Peter C.

2018-05-01

We investigate the scattering of classical and quantum particles in impulsive backgrounds fields. These fields model short outbursts of radiation propagating with the speed of light. The singular nature of the problem will be accounted for by the use of Colombeau’s generalized function which however give rise to ambiguities. It is the aim of the paper to show that these ambiguities can be overcome by implementing additional physical conditions, which in the non-singular case would be satisfied automatically. As example we discuss the scattering of classical, Klein–Gordon and Dirac particles in impulsive electromagnetic fields.

Tensor algebra over Hilbert space: Field theory in classical phase space

International Nuclear Information System (INIS)

Matos Neto, A.; Vianna, J.D.M.

1984-01-01

It is shown using tensor algebras, namely Symmetric and Grassmann algebras over Hilbert Space that it is possible to introduce field operators, associated to the Liouville equation of classical statistical mechanics, which are characterized by commutation (for Symmetric) and anticommutation (for Grassmann) rules. The procedure here presented shows by construction that many-particle classical systems admit an algebraic structure similar to that of quantum field theory. It is considered explicitly the case of n-particle systems interacting with an external potential. A new derivation of Schoenberg's result about the equivalence between his field theory in classical phase space and the usual classical statistical mechanics is obtained as a consequence of the algebraic structure of the theory as introduced by our method. (Author) [pt

Classical limit for scalar fields at high temperature

International Nuclear Information System (INIS)

Buchmueller, W.; Jakovac, A.

1998-01-01

We study real-time correlation functions in scalar quantum field theories at temperature T=1/β. We show that the behaviour of soft, long-wavelength modes is determined by classical statistical field theory. The loss of quantum coherence is due to interactions with the soft modes of the thermal bath. The soft modes are separated from the hard modes by an infrared cutoff Λ<<1/(ℎβ). Integrating out the hard modes yields an effective theory for the soft modes. The infrared cutoff Λ controls corrections to the classical limit which are O(ℎβΛ). As an application, the plasmon damping rate is calculated. (orig.)

Fast and robust estimation of spectro-temporal receptive fields using stochastic approximations.

Science.gov (United States)

Meyer, Arne F; Diepenbrock, Jan-Philipp; Ohl, Frank W; Anemüller, Jörn

2015-05-15

The receptive field (RF) represents the signal preferences of sensory neurons and is the primary analysis method for understanding sensory coding. While it is essential to estimate a neuron's RF, finding numerical solutions to increasingly complex RF models can become computationally intensive, in particular for high-dimensional stimuli or when many neurons are involved. Here we propose an optimization scheme based on stochastic approximations that facilitate this task. The basic idea is to derive solutions on a random subset rather than computing the full solution on the available data set. To test this, we applied different optimization schemes based on stochastic gradient descent (SGD) to both the generalized linear model (GLM) and a recently developed classification-based RF estimation approach. Using simulated and recorded responses, we demonstrate that RF parameter optimization based on state-of-the-art SGD algorithms produces robust estimates of the spectro-temporal receptive field (STRF). Results on recordings from the auditory midbrain demonstrate that stochastic approximations preserve both predictive power and tuning properties of STRFs. A correlation of 0.93 with the STRF derived from the full solution may be obtained in less than 10% of the full solution's estimation time. We also present an on-line algorithm that allows simultaneous monitoring of STRF properties of more than 30 neurons on a single computer. The proposed approach may not only prove helpful for large-scale recordings but also provides a more comprehensive characterization of neural tuning in experiments than standard tuning curves. Copyright © 2015 Elsevier B.V. All rights reserved.

Local receptive field constrained stacked sparse autoencoder for classification of hyperspectral images.

Science.gov (United States)

Wan, Xiaoqing; Zhao, Chunhui

2017-06-01

As a competitive machine learning algorithm, the stacked sparse autoencoder (SSA) has achieved outstanding popularity in exploiting high-level features for classification of hyperspectral images (HSIs). In general, in the SSA architecture, the nodes between adjacent layers are fully connected and need to be iteratively fine-tuned during the pretraining stage; however, the nodes of previous layers further away may be less likely to have a dense correlation to the given node of subsequent layers. Therefore, to reduce the classification error and increase the learning rate, this paper proposes the general framework of locally connected SSA; that is, the biologically inspired local receptive field (LRF) constrained SSA architecture is employed to simultaneously characterize the local correlations of spectral features and extract high-level feature representations of hyperspectral data. In addition, the appropriate receptive field constraint is concurrently updated by measuring the spatial distances from the neighbor nodes to the corresponding node. Finally, the efficient random forest classifier is cascaded to the last hidden layer of the SSA architecture as a benchmark classifier. Experimental results on two real HSI datasets demonstrate that the proposed hierarchical LRF constrained stacked sparse autoencoder and random forest (SSARF) provides encouraging results with respect to other contrastive methods, for instance, the improvements of overall accuracy in a range of 0.72%-10.87% for the Indian Pines dataset and 0.74%-7.90% for the Kennedy Space Center dataset; moreover, it generates lower running time compared with the result provided by similar SSARF based methodology.

Classical color fields as a dark matter candidate

OpenAIRE

Dzhunushaliev, Vladimir

2006-01-01

The model of Dark Matter is proposed in which the Dark Matter is a classical color field. The color fields are invisible as they may interact with colored elementary particles like 't Hooft - Polyakov monopole only. The comparison with the Universal Rotation Curve is carried out.

Classical and quantum ghosts

International Nuclear Information System (INIS)

Sbisà, Fulvio

2015-01-01

The aim of these notes is to provide a self-contained review of why it is generically a problem when a solution of a theory possesses ghost fields among the perturbation modes. We define what a ghost field is and we show that its presence is associated with a classical instability whenever the ghost field interacts with standard fields. We then show that the instability is more severe at quantum level, and that perturbative ghosts can exist only in low energy effective theories. However, if we do not consider very ad hoc choices, compatibility with observational constraints implies that low energy effective ghosts can exist only at the price of giving up Lorentz invariance or locality above the cut-off, in which case the cut-off has to be much lower that the energy scales we currently probe in particle colliders. We also comment on the possible role of extra degrees of freedom which break Lorentz invariance spontaneously. (paper)

Sharing information books with kindergartners: The role of parents’ extra-textual talk and socioeconomic status

NARCIS (Netherlands)

Mol, S.E.; Neuman, S.B.

2014-01-01

The purpose of the study was to explore how features of parent-child extra-textual talk during information book-sharing might vary across different socioeconomic backgrounds, and to determine if certain interactional patterns might mediate their effects on children's receptive and expressive

Comparing different stimulus configurations for population receptive field mapping in human fMRI

Directory of Open Access Journals (Sweden)

Ivan eAlvarez

2015-02-01

Full Text Available Population receptive field (pRF mapping is a widely used approach to measuring aggregate human visual receptive field properties by recording non-invasive signals using functional MRI. Despite growing interest, no study to date has systematically investigated the effects of different stimulus configurations on pRF estimates from human visual cortex. Here we compared the effects of three different stimulus configurations on a model-based approach to pRF estimation: size-invariant bars and eccentricity-scaled bars defined in Cartesian coordinates and traveling along the cardinal axes, and a novel simultaneous ‘wedge and ring’ stimulus defined in polar coordinates, systematically covering polar and eccentricity axes. We found that the presence or absence of eccentricity scaling had a significant effect on goodness of fit and pRF size estimates. Further, variability in pRF size estimates was directly influenced by stimulus configuration, particularly for higher visual areas including V5/MT+. Finally, we compared eccentricity estimation between phase-encoded and model-based pRF approaches. We observed a tendency for more peripheral eccentricity estimates using phase-encoded methods, independent of stimulus size. We conclude that both eccentricity scaling and polar rather than Cartesian stimulus configuration are important considerations for optimal experimental design in pRF mapping. While all stimulus configurations produce adequate estimates, simultaneous wedge and ring stimulation produced higher fit reliability, with a significant advantage in reduced acquisition time.

Stigma development and receptivity in almond (Prunus dulcis).

Science.gov (United States)

Yi, Weiguang; Law, S Edward; McCoy, Dennis; Wetzstein, Hazel Y

2006-01-01

Fertilization is essential in almond production, and pollination can be limiting in production areas. This study investigated stigma receptivity under defined developmental stages to clarify the relationship between stigma morphology, pollen germination, tube growth and fruit set. Light and scanning electron microscopy were employed to examine stigma development at seven stages of flower development ranging from buds that were swollen to flowers in which petals were abscising. Flowers at different stages were hand pollinated and pollen germination and tube growth assessed. Artificial pollinations in the field were conducted to determine the effect of flower age on fruit set. Later stages of flower development exhibited greater stigma receptivity, i.e. higher percentages of pollen germination and more extensive tube growth occurred in older (those opened to the flat petal stage or exhibiting petal fall) than younger flowers. Enhanced stigma receptivity was associated with elongation of stigmatic papillae and increased amounts of stigmatic exudate that inundated papillae at later developmental stages. Field pollinations indicated that the stigma was still receptive and nut set was maintained in older flowers. Stigma receptivity in almond does not become optimal until flowers are past the fully open stage. The stigma is still receptive and fruit set is maintained in flowers even at the stage when petals are abscising. Strategies to enhance pollination and crop yield, including the timing and placement of honey bees, should consider the effectiveness of developmentally advanced flowers.

Effects of wind turbines on UHF television reception: field tests in Denmark, November 1991

International Nuclear Information System (INIS)

Wright, D.T.

1992-01-01

As a result of a planning application for a wind farm comprising 20 wind turbines at Tynewydd Farm, Gilfach Goch in Mid Glamorgan, it became necessary to produce a Report discussing any detrimental effects the proposal might have on UHF television reception. In order to make that Report as definitive as possible, it was decided to carry out field tests on the exact model of wind turbine to be used to Tynewydd. This required a field trip to Denmark, and the opportunity was taken to make measurements on two other models of turbine at the same time. This Report presents the analysis of the results for all three turbines. (Author)

Classical and quantum mechanics of non-abelian gauge fields

International Nuclear Information System (INIS)

Savvidy, G.K.

1984-01-01

Classical and quantum mechanics of non-abelian gauge fields are investigated both with and without spontaneous symmetry breaking. The fundamental subsystem (FS) of Yang-Mills classical mechanics (YMCM) is considered. It is shown to be a Kolmogorov K-system, and hence to have strong statistical properties. Integrable systems are also found, to which in terms of KAM theory Yang-Mills-Higgs classical mechanics (YMHCM) is close. Quantum-mechanical properties of the YM system and their relation to the problem of confinement are discussed. (orig.)

Grassmann expansion of the classical N=2 supergravity field equations

International Nuclear Information System (INIS)

Embacher, F.

1984-01-01

The classical field equations of N=2 supergravity are expanded with respect to an infinite dimensional Grassmann algebra. The general freedom in constructing classical solution is exhibited. As an application, a uniqueness theorem for supersymmetric extreme black holes is given. (Author)

Classical transport in field reversed mirrors: reactor implications

International Nuclear Information System (INIS)

Auerbach, S.P.; Condit, W.C.

1980-01-01

Assuming that the field-reversed mirror (or the closely related spheromak) turns out to be stable, the next crucial issue is transport of particles and heat. Of particular concern is the field null on axis (the X-point), which at first glance seems to allow particles to flow out unhindered. We have evaluated the classical diffusion coefficients for particles and heat in field-reversed mirrors, with particular reference to a class of Hill's vortex models. Two fairly surprising results emerge from this study. First, the diffusion-driven flow of particles and heat is finite at the X-points. This may be traced to the geometrical constraint that the current (and hence the ion-electron drag force, which causes cross-field transport) must vanish on axis. This conclusion holds for any transport model. Second, the classical diffusion coefficient D(psi), which governs both particle and heat flux, is finite on the separatrix. Indeed, in a wide class of Hill's vortex equilibria (spherical, oblate, or prolate) D(psi) is essentially independent of psi (except for the usual factor of n

Remarks on the classical limit of quantum field theories

International Nuclear Information System (INIS)

Eckmann, J.P.

1977-01-01

Recently, there has been an increasing interest in computing quantum mechanical corrections to solutions of classical field equations. In this note, proceeding in the opposite way, theorems about the classical limit of relativistic quantum field models are summarized. These results are a byproduct of the so called 'constructive' approach to quantum field theory. Section 1 deals with generalities; in Section 2 the situation where no phase transitions occur is discussed in the limit h→0; and in Section 3 one result in the case where such a transition occurs is reformulated (Glimm et al). The validity of the loop expansion is discussed. It seems however that the tools to show the rigorous validity of soliton calculations are not yet prepared. (Auth.)

Beyond Reception

DEFF Research Database (Denmark)

This book argues that it is time to rethink reception as a traditional paradigm for understanding the relation between the ancient Greco-Roman traditions and early Judaism and Christianity. The concept of reception implies taking something from one fixed box into another, often a chronological...... intend to develop a more multi-faceted view of such precesses and to go beyond the term reception....

Classical diffusion in a field-reversed mirror

International Nuclear Information System (INIS)

Auerbach, S.P.; Condit, W.C.

1981-01-01

Classical transport of particles and heat in field-reversed mirrors is discussed. The X-points (field nulls on axis) are shown to have no deleterious effect on transport; this conclusion is true for any transport model. For an elongated Hill's vortex equilibrium the classical diffusion coefficient is calculated analytically and used to construct an analytic solution to the transport equation for particles or energy; this yields exact results for particle and energy confinement times. These life-times are roughly 3 to 6 times shorter than previous heuristic estimates. Experimentally determined life-times are within a factor of 3 to 4 of our estimates. To assess the impact of these results on reactor designs, the authors construct an analytic reactor model in which neutral-beam input balances ion heat loss. Energy loss due to synchrotron radiation is calculated analytically and shown to be negligible, even with no wall reflection. Formulas are presented which give the reactor parameters in terms of plasma temperature, energy multiplication factor Q, and allowed neutron wall loading. The effect of anomalous resistivity is incorporated heuristically by assuming an anomalous resistivity which is enhanced by a factor A over classical resistivity. For large A the minimum power of a reactor scales as Asup(11/6). A=50 gives a reactor design which still seems reasonable, but A=200 leads to extremely large, high-power reactors. (author)

Visual Acuity and Its Dependence Upon Receptor Density and Retinal Ganglion Cell Receptive Field Overlap.

Science.gov (United States)

1981-11-01

organization of retinal receptive fields in monkeys and cats has been used to model the information flow to the retina in relation to the psychophysical...EXPERIMENTAL PROCEDURE Types of Animals Used Three types of monkeys were used in the present study, rhesus (Macaca mulatta), the Himalayan Macaque (Macaca...during the course of the program, although one died of Shigella infection. Attempts were made to trade the animals with local users in order to obtain

The Role of Classical Music in the Construction of Nationalism

DEFF Research Database (Denmark)

Brincker, Benedikte

2014-01-01

This paper explores the role of classical music in the construction of nationalism in the twentieth century. It takes its point of departure in the Danish composer Carl Nielsen and analyses competing interpretations and receptions of his works. The paper seeks to move beyond the single case study...... classical music and nationalism....

New solutions of a nonlinear classical field theory

International Nuclear Information System (INIS)

Marques, G.C.; Ventura, I.

1975-01-01

New solutions of a relativistic, classical, field theoretical model having logarithmic nonlinearities are obtained. Some of these solutions correspond to field not bounded in time but having finite energy and charge. There are no bounded solutions (bound states and resonances in particular) if the charge exceeds a certain value. This effect is due to the existance of a 'charge barrier' in this field theoretical model. All calculations are performed in a number of spatial dimensions [pt

Classical calculation of radiative lifetimes of atomic hydrogen in a homogeneous magnetic field

International Nuclear Information System (INIS)

Horbatsch, M.W.; Hessels, E.A.; Horbatsch, M.

2005-01-01

Radiative lifetimes of hydrogenic atoms in a homogeneous magnetic field of moderate strength are calculated on the basis of classical radiation. The modifications of the Keplerian orbits due to the magnetic field are incorporated by classical perturbation theory. The model is complemented by a classical radiative decay calculation using the radiated Larmor power. A recently derived highly accurate formula for the transition rate of a field-free hydrogenic state is averaged over the angular momentum oscillations caused by the magnetic field. The resulting radiative lifetimes for diamagnetic eigenstates classified by n,m and the diamagnetic energy shift C compare well with quantum results

It's Not Given Us to Foretell How Our Words Will Echo through the Ages: The Reception of Novel Ideas by Scientific Community

Directory of Open Access Journals (Sweden)

Valentin Bazhanov

2009-01-01

Full Text Available The paper reveals some mostly unnoticed and unexpected trends in reception of novel ideas in science. The author formulates certain principles of the reception of these ideas by scientific communities and justifies them by examples from modern mathematics and non-classical logic.

Classical and quantum Big Brake cosmology for scalar field and tachyonic models

Energy Technology Data Exchange (ETDEWEB)

Kamenshchik, A. Yu. [Dipartimento di Fisica e Astronomia and INFN, Via Irnerio 46, 40126 Bologna (Italy) and L.D. Landau Institute for Theoretical Physics of the Russian Academy of Sciences, Kosygin str. 2, 119334 Moscow (Russian Federation); Manti, S. [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy)

2013-02-21

We study a relation between the cosmological singularities in classical and quantum theory, comparing the classical and quantum dynamics in some models possessing the Big Brake singularity - the model based on a scalar field and two models based on a tachyon-pseudo-tachyon field . It is shown that the effect of quantum avoidance is absent for the soft singularities of the Big Brake type while it is present for the Big Bang and Big Crunch singularities. Thus, there is some kind of a classical - quantum correspondence, because soft singularities are traversable in classical cosmology, while the strong Big Bang and Big Crunch singularities are not traversable.

Classical and quantum Big Brake cosmology for scalar field and tachyonic models

International Nuclear Information System (INIS)

Kamenshchik, A. Yu.; Manti, S.

2013-01-01

We study a relation between the cosmological singularities in classical and quantum theory, comparing the classical and quantum dynamics in some models possessing the Big Brake singularity - the model based on a scalar field and two models based on a tachyon-pseudo-tachyon field . It is shown that the effect of quantum avoidance is absent for the soft singularities of the Big Brake type while it is present for the Big Bang and Big Crunch singularities. Thus, there is some kind of a classical - quantum correspondence, because soft singularities are traversable in classical cosmology, while the strong Big Bang and Big Crunch singularities are not traversable.

Classical trajectory perspective of atomic ionization in strong laser fields. Semiclassical modeling

International Nuclear Information System (INIS)

Liu, Jie

2014-01-01

Dealing with timely and interesting issues in strong laser physics. Illustrates complex strong field atomic ionization with the simple semiclassical model of classical trajectory perspective for the first time. Provides a theoretical model that can be used to account for recent experiments. The ionization of atoms and molecules in strong laser fields is an active field in modern physics and has versatile applications in such as attosecond physics, X-ray generation, inertial confined fusion (ICF), medical science and so on. Classical Trajectory Perspective of Atomic Ionization in Strong Laser Fields covers the basic concepts in this field and discusses many interesting topics using the semiclassical model of classical trajectory ensemble simulation, which is one of the most successful ionization models and has the advantages of a clear picture, feasible computing and accounting for many exquisite experiments quantitatively. The book also presents many applications of the model in such topics as the single ionization, double ionization, neutral atom acceleration and other timely issues in strong field physics, and delivers useful messages to readers with presenting the classical trajectory perspective on the strong field atomic ionization. The book is intended for graduate students and researchers in the field of laser physics, atom molecule physics and theoretical physics. Dr. Jie Liu is a professor of Institute of Applied Physics and Computational Mathematics, China and Peking University.

The Past in the Future: Problems and Potentials of Historical Reception Studies.

Science.gov (United States)

Jensen, Klaus Bruhn

1993-01-01

Gives examples of how qualitative methodologies have been employed to study media reception in the present. Identifies some forms of evidence that can creatively fill the gaps in knowledge about media reception in the past. Argues that the field must develop databases documenting media reception, which may broaden the scope of audience research in…

Classical understanding of electron vortex beams in a uniform magnetic field

Energy Technology Data Exchange (ETDEWEB)

Han, Yeong Deok [Department of Computer Science and Engineering, Woosuk University, Wanju, Cheonbuk, 565-701 (Korea, Republic of); Choi, Taeseung, E-mail: tschoi@swu.ac.kr [Division of Applied Food System, College of Natural Science, Seoul Women' s University, Seoul 139-774 (Korea, Republic of); School of Computational Sciences, Korea Institute for Advanced Study, Seoul 130-012 (Korea, Republic of)

2017-04-25

Recently, interesting observations on electron vortex beams have been made. We propose a classical model that shows vortex-like motion due to suitably-synchronized motion of each electron's cyclotron motion in a uniform magnetic field. It is shown that some basic features of electron vortex beams in a uniform magnetic field, such as azimuthal currents, the relation between energy and kinetic angular momentum, and the parallel-axis theorem are understandable by using this classical model. We also show that the time-dependence of kinetic angular momentum of electron vortex beams could be understood as an effect of a specific nonuniform distribution of classical electrons. - Highlights: • A classical model for electron vortex beams is proposed. • The basic features of azimuthal currents could be understood by using this model. • The kinetic angular momentum of electron vortex beams is intuitively understandable.

Replicating receptive fields of simple and complex cells in primary visual cortex in a neuronal network model with temporal and population sparseness and reliability.

Science.gov (United States)

Tanaka, Takuma; Aoyagi, Toshio; Kaneko, Takeshi

2012-10-01

We propose a new principle for replicating receptive field properties of neurons in the primary visual cortex. We derive a learning rule for a feedforward network, which maintains a low firing rate for the output neurons (resulting in temporal sparseness) and allows only a small subset of the neurons in the network to fire at any given time (resulting in population sparseness). Our learning rule also sets the firing rates of the output neurons at each time step to near-maximum or near-minimum levels, resulting in neuronal reliability. The learning rule is simple enough to be written in spatially and temporally local forms. After the learning stage is performed using input image patches of natural scenes, output neurons in the model network are found to exhibit simple-cell-like receptive field properties. When the output of these simple-cell-like neurons are input to another model layer using the same learning rule, the second-layer output neurons after learning become less sensitive to the phase of gratings than the simple-cell-like input neurons. In particular, some of the second-layer output neurons become completely phase invariant, owing to the convergence of the connections from first-layer neurons with similar orientation selectivity to second-layer neurons in the model network. We examine the parameter dependencies of the receptive field properties of the model neurons after learning and discuss their biological implications. We also show that the localized learning rule is consistent with experimental results concerning neuronal plasticity and can replicate the receptive fields of simple and complex cells.

Classical trajectories and quantum field theory

International Nuclear Information System (INIS)

Vitiello, Giuseppe; Istituto Nazionale di Fisica Nucleare, Salerno

2005-01-01

The density matrix and the Wigner function formalism requires the doubling of the degrees of freedom in quantum mechanics (QM) and quantum field theory (QFT). The doubled degrees of freedom play the role of the thermal bath or environment degrees of freedom and are entangled with the system degrees of freedom. They also account for quantum noise in the fluctuating random forces in the system-environment coupling. The algebraic structure of QFT turns out to be the one of the deformed Hopf algebra. In such a frame, the trajectories in the space of the unitarily inequivalent representations of the canonical commutation relations turn out to be classical trajectories and, under convenient conditions, they may exhibit properties typical of classical chaotic trajectories in nonlinear dynamics. The quantum Brownian motion and the two-slit experiment in QM are discussed in connection with the doubling of the degrees of freedom. (author)

Special relativity and classical field theory

CERN Document Server

Susskind, Leonard

2017-01-01

Physicist Leonard Susskind and data engineer Art Friedman are back. This time, they introduce readers to Einstein's special relativity and Maxwell's classical field theory. Using their typical brand of real math, enlightening drawings, and humor, Susskind and Friedman walk us through the complexities of waves, forces, and particles by exploring special relativity and electromagnetism. It's a must-read for both devotees of the series and any armchair physicist who wants to improve their knowledge of physics' deepest truths.

Generalized force in classical field theory. [Euler-Lagrange equations

Energy Technology Data Exchange (ETDEWEB)

Krause, J [Universidad Central de Venezuela, Caracas

1976-02-01

The source strengths of the Euler-Lagrange equations, for a system of interacting fields, are heuristically interpreted as generalized forces. The canonical form of the energy-momentum tensor thus consistently appears, without recourse to space-time symmetry arguments. A concept of 'conservative' generalized force in classical field theory is also briefly discussed.

From classical to quantum fields

CERN Document Server

Baulieu, Laurent; Sénéor, Roland

2017-01-01

Quantum Field Theory has become the universal language of most modern theoretical physics. This introductory textbook shows how this beautiful theory offers the correct mathematical framework to describe and understand the fundamental interactions of elementary particles. The book begins with a brief reminder of basic classical field theories, electrodynamics and general relativity, as well as their symmetry properties, and proceeds with the principles of quantisation following Feynman's path integral approach. Special care is used at every step to illustrate the correct mathematical formulation of the underlying assumptions. Gauge theories and the problems encountered in their quantisation are discussed in detail. The last chapters contain a full description of the Standard Model of particle physics and the attempts to go beyond it, such as grand unified theories and supersymmetry. Written for advanced undergraduate and beginning graduate students in physics and mathematics, the book could also serve as a re...

Central sensitization in spinal cord injured humans assessed by reflex receptive fields

DEFF Research Database (Denmark)

Biurrun Manresa, José Alberto; Finnerup, Nanna Susanne Brix; Johannesen, Inger Lauge

2014-01-01

OBJECTIVE: To investigate the effects of central sensitization, elicited by intramuscular injection of capsaicin, by comparing the reflex receptive fields (RRF) of spinally-intact volunteers and spinal cord injured volunteers that present presensitized spinal nociceptive mechanisms. METHODS...... after an intramuscular injection of capsaicin in the foot sole in order to induce central sensitization. RESULTS: Both groups presented RRF expansion and lowered NWR thresholds immediately after capsaicin injection, reflected by the enlargement of RRF sensitivity areas and RRF probability areas....... Moreover, the topography of the RRF sensitivity and probability areas were significantly different in SCI volunteers compared to NI volunteers in terms of size and shape. CONCLUSIONS: SCI volunteers can develop central sensitization, despite adaptive/maladaptive changes in synaptic plasticity and lack...

[Comparative assessment of MR-semiotics of acutest intracerebral hematomas in low- and extra high-field frequency magnetic resonance tomography].

Science.gov (United States)

Skvortsova, V I; Burenchev, D V; Tvorogova, T V; Guseva, O I; Prokhorov, A V; Smirnov, A M; Kupriianov, D A; Pirogov, Iu A

2009-01-01

An objective of the study was to compare sensitivity of low- and extra high-field frequency magnetic resonance (MR) tomography of acutest intracerebral hematomas (ICH) and to assess differences between symptoms in obtained images. A study was conducted using experimental ICH in rats (n=6). Hematomas were formed by two injections of autologic blood into the brain. MR-devices "Bio Spec 70/30" with magnetic field strength of 7 T and "Ellipse-150" with magnetic field strength of 0,15 T were used in the study. MR-tomography was carried out 3-5 h after the injections. Both MR-devices revealed the presence of pathological lesion in all animals. Extra highfield frequency MR-tomography showed the specific signs of ICH caused by the paramagnetic effect of deoxyhemoglobin in T2 and T2*-weighted images (WI) and low frequency MR-tomography - in T2*-WI only. The comparable sensitivity of low- and extra high-field frequency MR-devices in acutest ICH was established.

Classical open-string field theory: A∞-algebra, renormalization group and boundary states

International Nuclear Information System (INIS)

Nakatsu, Toshio

2002-01-01

We investigate classical bosonic open-string field theory from the perspective of the Wilson renormalization group of world-sheet theory. The microscopic action is identified with Witten's covariant cubic action and the short-distance cut-off scale is introduced by length of open-string strip which appears in the Schwinger representation of open-string propagator. Classical open-string field theory in the title means open-string field theory governed by a classical part of the low energy action. It is obtained by integrating out suitable tree interactions of open-strings and is of non-polynomial type. We study this theory by using the BV formalism. It turns out to be deeply related with deformation theory of A ∞ -algebra. We introduce renormalization group equation of this theory and discuss it from several aspects. It is also discussed that this theory is interpreted as a boundary open-string field theory. Closed-string BRST charge and boundary states of closed-string field theory in the presence of open-string field play important roles

Polymer quantization of the free scalar field and its classical limit

Energy Technology Data Exchange (ETDEWEB)

Laddha, Alok; Varadarajan, Madhavan, E-mail: alok@rri.res.i, E-mail: madhavan@rri.res.i [Raman Research Institute, Bangalore 560 080 (India)

2010-09-07

Building on prior work, a generally covariant reformulation of a free scalar field theory on the flat Lorentzian cylinder is quantized using loop quantum gravity (LQG)-type 'polymer' representations. This quantization of the continuum classical theory yields a quantum theory which lives on a discrete spacetime lattice. We explicitly construct a state in the polymer Hilbert space which reproduces the standard Fock vacuum two-point functions for long-wavelength modes of the scalar field. Our construction indicates that the continuum classical theory emerges under coarse graining. All our considerations are free of the 'triangulation' ambiguities which plague attempts to define quantum dynamics in LQG. Our work constitutes the first complete LQG-type quantization of a generally covariant field theory together with a semi-classical analysis of the true degrees of freedom and thus provides a perfect infinite-dimensional toy model to study open issues in LQG, particularly those pertaining to the definition of quantum dynamics.

Colored, spinning classical particle in an external non-Abelian gauge field

International Nuclear Information System (INIS)

Arodz, H.

1982-04-01

Classical non-relativistic equations of motion are derived for a colored, spinning point-like particle in an external SU(2) gauge field from Dirac equation. It is found that in addition to the classical spin and color spin vectors, S, I, it is necessary to introduce a new classical dynamical variable [Jsup(ab)], a,b = 1,2,3, describing a mixing of the spin and color. The constraint relations between [Jsup(ab)], S, I are also found. (Auth.)

Semi-classical derivation of charge-quantization through charge-field self-interaction

International Nuclear Information System (INIS)

Kosok, M.; Madhyastha, V.L.

1990-01-01

A semi-classical synthesis of classical mechanics, wave mechanics, and special relativity yields a unique nonlinear energy-wave structure of relations (velocity triad uv = c 2 ) fundamental to modern physics. Through the above vehicle, using Maxwell's equations, charge quantization and the fine structure constant are derived. It is shown that the numerical value of the nonlinear charge-field self-interaction range for the electron is of the order of 10 -13 m, which is greater than the classical electron radius but less than the Compton wavelength of the electron. Finally, it is suggested that the structure of the electron-in-space is expressed by a self-extending nonlinear ''fractal geometry'' based on derived numerical values obtained from our model, thus opening this presentation of charge-field structure to experimental testing for possible verification

Quantum correlations and dynamics from classical random fields valued in complex Hilbert spaces

International Nuclear Information System (INIS)

Khrennikov, Andrei

2010-01-01

One of the crucial differences between mathematical models of classical and quantum mechanics (QM) is the use of the tensor product of the state spaces of subsystems as the state space of the corresponding composite system. (To describe an ensemble of classical composite systems, one uses random variables taking values in the Cartesian product of the state spaces of subsystems.) We show that, nevertheless, it is possible to establish a natural correspondence between the classical and the quantum probabilistic descriptions of composite systems. Quantum averages for composite systems (including entangled) can be represented as averages with respect to classical random fields. It is essentially what Albert Einstein dreamed of. QM is represented as classical statistical mechanics with infinite-dimensional phase space. While the mathematical construction is completely rigorous, its physical interpretation is a complicated problem. We present the basic physical interpretation of prequantum classical statistical field theory in Sec. II. However, this is only the first step toward real physical theory.

The public reception of the Research Assessment Exercise 1996.

Directory of Open Access Journals (Sweden)

Julian Warner

1998-01-01

Full Text Available This paper reviews the public reception of the Research Assessment Exercise 1996 (RAE from its announcement in December 1996 to the decline of discussion at end May 1997. A model for diffusion of the RAE is established which distinguishes extra-communal (or exoteric from intra-communal (or esoteric media. The different characteristics of each medium and the changing nature of the discussion over time are considered. Different themes are distinguished in the public reception of the RAE: the spatial distribution of research; the organisation of universities; disciplinary differences in understanding; a perceived conflict between research and teaching; the development of a culture of accountability; and analogies with the organisation of professional football. In conclusion, it is suggested that the RAE and its effects can be more fully considered from the perspective of scholarly communication and understandings of the development of knowledge than it has been by previous contributions in information science, which have concentrated on the possibility of more efficient implementation of existing processes. A fundamental responsibility for funding councils is also identified: to promote the overall health of university education and research, while establishing meaningful differentiations between units.

General treatment of quantum and classical spinning particles in external fields

Science.gov (United States)

Obukhov, Yuri N.; Silenko, Alexander J.; Teryaev, Oleg V.

2017-11-01

We develop the general theory of spinning particles with electric and magnetic dipole moments moving in arbitrary electromagnetic, inertial, and gravitational fields. Both the quantum-mechanical and classical dynamics is investigated. We start from the covariant Dirac equation extended to a spin-1/2 fermion with anomalous magnetic and electric dipole moments and then perform the relativistic Foldy-Wouthuysen transformation. This transformation allows us to obtain the quantum-mechanical equations of motion for the physical operators in the Schrödinger form and to establish the classical limit of relativistic quantum mechanics. The results obtained are then compared to the general classical description of the spinning particle interacting with electromagnetic, inertial and gravitational fields. The complete agreement between the quantum mechanics and the classical theory is proven in the general case. As an application of the results obtained, we consider the dynamics of a spinning particle in a gravitational wave and analyze the prospects of using the magnetic resonance setup to find possible manifestations of the gravitational wave on spin.

Problems of generation and reception of gravitational waves

International Nuclear Information System (INIS)

Pisarev, A.F.

1975-01-01

The present day status of the problems of gravitation, wave radiation and reception is surveyed. The physical presentation and mathematical description of the processes of radiation, propagation and interaction of gravitation waves with matter and the electromagnetic field are given. The experiments on the search for gravitation waves of astophysical nature are analysed. The laboratory and cosmic sources of these waves and the methods of their reception are described. Special attention is drawn to the analysis of the proposals to perform a complete laboratory gravitation wave experiment

Introduction to classical and quantum field theory

International Nuclear Information System (INIS)

Ng, Tai-Kai

2009-01-01

This is the first introductory textbook on quantum field theory to be written from the point of view of condensed matter physics. As such, it presents the basic concepts and techniques of statistical field theory, clearly explaining how and why they are integrated into modern quantum (and classical) field theory, and includes the latest developments. Written by an expert in the field, with a broad experience in teaching and training, it manages to present such substantial topics as phases and phase transitions or solitons and instantons in an accessible and concise way. Divided into three parts, the first part covers fundamental physics and the mathematics background needed by students in order to enter the field, while the second part introduces more advanced concepts and techniques. Part III discusses applications of quantum field theory to a few basic problems. The emphasis here lies on how modern concepts of quantum field theory are embedded in these approaches, and also on the limitations of standard quantum field theory techniques in facing, 'real' physics problems. Throughout there are numerous end-of-chapter problems, and a free solutions manual is available for lecturers. (orig.)

Stabilization of the extra dimension size in RS model by bulk Higgs field

International Nuclear Information System (INIS)

Egorov, V O; Volobuev, I P

2017-01-01

An extension of the Standard Model is considered, which is built on the basis of a stabilized Randall-Sundrum model with two branes. The stabilization of the extra dimension size is achieved with the help of a five-dimensional Higgs field, which plays the role of the Goldberger-Wise field. The stabilization makes the radion massive, and all the fermion fields, which are assumed to be localized on the TeV brane, get their masses due to the interaction with the boundary value of the Higgs field. The gauge invariance of the theory demands that the electroweak gauge fields also live in the bulk. The equations of motion for the background field configurations and for the field fluctuations against a background solution are obtained. The interaction of the bulk Higgs field with the multidimensional gauge field is studied and possible values of the model parameters are estimated. (paper)

Lorentz invariance from classical particle paths in quantum field theory of electric and magnetic charge

International Nuclear Information System (INIS)

Brandt, R.A.; Neri, F.; Zwanziger, D.

1979-01-01

We establish the Lorentz invariance of the quantum field theory of electric and magnetic charge. This is a priori implausible because the theory is the second-quantized version of a classical field theory which is inconsistent if the minimally coupled charged fields are smooth functions. For our proof we express the generating functional for the gauge-invariant Green's functions of quantum electrodynamics: with or without magnetic charge: as a path integral over the trajectories of classical charged point particles. The electric-electric and electric-magnetic interactions contribute factors exp(JDJ) and exp(JD'K), where J and K are the electric and magnetic currents of classical point particles and D is the usual photon propagator. The propagator D' involves the Dirac string but exp(JD'K) depends on it only through a topological integer linking string and classical particle trajectories. The charge quantization condition e/sub i/g/sub j/ - g/sub i/e/sub j/ = integer then suffices to make the gauge-invariant Green's functions string independent. By implication our formulation shows that if the Green's functions of quantum electrodynamics are expressed as usual as functional integrals over classical charged fields, the smooth field configurations have measure zero and all the support of the Feynman measure lies on the trajectories of classical point particles

Predicting Volleyball Serve-Reception

NARCIS (Netherlands)

Paulo, Ana; Zaal, Frank T J M; Fonseca, Sofia; Araujo, Duarte

2016-01-01

Serve and serve-reception performance have predicted success in volleyball. Given the impact of serve-reception on the game, we aimed at understanding what it is in the serve and receiver's actions that determines the selection of the type of pass used in serve-reception and its efficacy. Four

How to Explain Receptivity to Conjunction-Fallacy Inhibition Training: Evidence from the Iowa Gambling Task

Science.gov (United States)

Cassotti, Mathieu; Moutier, Sylvain

2010-01-01

Intuitive predictions and judgments under conditions of uncertainty are often mediated by judgment heuristics that sometimes lead to biases. Using the classical conjunction bias example, the present study examines the relationship between receptivity to metacognitive executive training and emotion-based learning ability indexed by Iowa Gambling…

Local gauge invariant Lagrangeans in classical field theories

International Nuclear Information System (INIS)

Grigore, D.R.

1982-07-01

We investigate the most general local gauge invariant Lagrangean in the framework of classical field theory. We rederive esentially Utiyama's result with a slight generalization. Our proof makes clear the importance of the so called current conditions, i.e. the requirement that the Noether currents are different from zero. This condition is of importance both in the general motivation for the introduction of the Yang-Mills fields and for the actual proof. Some comments are made about the basic mathematical structure of the problem - the gauge group. (author)

Quantum dynamics in transverse-field Ising models from classical networks

Directory of Open Access Journals (Sweden)

Markus Schmitt, Markus Heyl

2018-02-01

Full Text Available The efficient representation of quantum many-body states with classical resources is a key challenge in quantum many-body theory. In this work we analytically construct classical networks for the description of the quantum dynamics in transverse-field Ising models that can be solved efficiently using Monte Carlo techniques. Our perturbative construction encodes time-evolved quantum states of spin-1/2 systems in a network of classical spins with local couplings and can be directly generalized to other spin systems and higher spins. Using this construction we compute the transient dynamics in one, two, and three dimensions including local observables, entanglement production, and Loschmidt amplitudes using Monte Carlo algorithms and demonstrate the accuracy of this approach by comparisons to exact results. We include a mapping to equivalent artificial neural networks, which were recently introduced to provide a universal structure for classical network wave functions.

Motion of small bodies in classical field theory

International Nuclear Information System (INIS)

Gralla, Samuel E.

2010-01-01

I show how prior work with R. Wald on geodesic motion in general relativity can be generalized to classical field theories of a metric and other tensor fields on four-dimensional spacetime that (1) are second-order and (2) follow from a diffeomorphism-covariant Lagrangian. The approach is to consider a one-parameter-family of solutions to the field equations satisfying certain assumptions designed to reflect the existence of a body whose size, mass, and various charges are simultaneously scaled to zero. (That such solutions exist places a further restriction on the class of theories to which our results apply.) Assumptions are made only on the spacetime region outside of the body, so that the results apply independent of the body's composition (and, e.g., black holes are allowed). The worldline 'left behind' by the shrinking, disappearing body is interpreted as its lowest-order motion. An equation for this worldline follows from the 'Bianchi identity' for the theory, without use of any properties of the field equations beyond their being second-order. The form of the force law for a theory therefore depends only on the ranks of its various tensor fields; the detailed properties of the field equations are relevant only for determining the charges for a particular body (which are the ''monopoles'' of its exterior fields in a suitable limiting sense). I explicitly derive the force law (and mass-evolution law) in the case of scalar and vector fields, and give the recipe in the higher-rank case. Note that the vector force law is quite complicated, simplifying to the Lorentz force law only in the presence of the Maxwell gauge symmetry. Example applications of the results are the motion of 'chameleon' bodies beyond the Newtonian limit, and the motion of bodies in (classical) non-Abelian gauge theory. I also make some comments on the role that scaling plays in the appearance of universality in the motion of bodies.

Classical limit of a quantum particle in an external Yang-Mills field

International Nuclear Information System (INIS)

Moschella, U.

1989-01-01

It is studied the classical limit of a quantum particle in an external non-abelian gauge field. It is shown that the unitary group describing the quantum fluctuations around any classic phase orbit has a classical limit when h tends to zero under very general conditions on the potentials. It is also proved the self-adjointness of the Hamilton's operator of the quantum theory for a large class of potentials. Some applications of the theory are finally exposed

Recurrence spectroscopy of atoms in electric fields: Failure of classical scaling laws near bifurcations

International Nuclear Information System (INIS)

Shaw, J.A.; Robicheaux, F.

1998-01-01

The photoabsorption spectra of atoms in a static external electric field shows modulations from recurrences: electron waves that go out from and return to the vicinity of the atomic core. Closed-orbit theory predicts the amplitudes and phases of these modulations in terms of closed classical orbits. A classical scaling law relates the properties of a closed orbit at one energy and field strength to its properties at another energy and field strength at fixed scaled energy ε=EF -1/2 . The scaling law states that the recurrence strength of orbits along the electric field axis scale as F 1/4 . We show how this law fails near bifurcations when the effective Planck constant ℎ≡ℎF 1/4 increases with increasing field at fixed ε. The recurrences of orbits away from the axis scale as F 1/8 in accordance with the classical prediction. These deviations from the classical scaling law are important in interpreting the recurrence spectra of atoms in current experiments. This leads to an extension of the uniform approximation developed by Gao and Delos [Phys. Rev. A 56, 356 (1997)] to complex momenta. copyright 1998 The American Physical Society

Second quantization of classical nonlinear relativistic field theory. Pt. 2

International Nuclear Information System (INIS)

Balaban, T.

1976-01-01

The construction of a relativistic interacting local quantum field is given in two steps: first the classical nonlinear relativistic field theory is written down in terms of Poisson brackets, with initial conditions as canonical variables: next a representation of Poisson bracket Lie algebra by means of linear operators in the topological vector space is given and an explicit form of a local interacting relativistic quantum field PHI is obtained. (orig./BJ) [de

Constrained variational calculus for higher order classical field theories

Energy Technology Data Exchange (ETDEWEB)

Campos, Cedric M; De Leon, Manuel; De Diego, David MartIn, E-mail: cedricmc@icmat.e, E-mail: mdeleon@icmat.e, E-mail: david.martin@icmat.e [Instituto de Ciencias Matematicas, CSIC-UAM-UC3M-UCM, Serrano 123, 28006 Madrid (Spain)

2010-11-12

We develop an intrinsic geometrical setting for higher order constrained field theories. As a main tool we use an appropriate generalization of the classical Skinner-Rusk formalism. Some examples of applications are studied, in particular to the geometrical description of optimal control theory for partial differential equations.

Constrained variational calculus for higher order classical field theories

International Nuclear Information System (INIS)

Campos, Cedric M; De Leon, Manuel; De Diego, David MartIn

2010-01-01

We develop an intrinsic geometrical setting for higher order constrained field theories. As a main tool we use an appropriate generalization of the classical Skinner-Rusk formalism. Some examples of applications are studied, in particular to the geometrical description of optimal control theory for partial differential equations.

Fluctuating local field method probed for a description of small classical correlated lattices

Science.gov (United States)

Rubtsov, Alexey N.

2018-05-01

Thermal-equilibrated finite classical lattices are considered as a minimal model of the systems showing an interplay between low-energy collective fluctuations and single-site degrees of freedom. Standard local field approach, as well as classical limit of the bosonic DMFT method, do not provide a satisfactory description of Ising and Heisenberg small lattices subjected to an external polarizing field. We show that a dramatic improvement can be achieved within a simple approach, in which the local field appears to be a fluctuating quantity related to the low-energy degree(s) of freedom.

Classical field theory on electrodynamics, non-Abelian gauge theories and gravitation

CERN Document Server

Scheck, Florian

2012-01-01

The book describes Maxwell's equations first in their integral, directly testable form, then moves on to their local formulation. The first two chapters cover all essential properties of Maxwell's equations, including their symmetries and their covariance in a modern notation. Chapter 3 is devoted to Maxwell theory as a classical field theory and to solutions of the wave equation. Chapter 4 deals with important applications of Maxwell theory. It includes topical subjects such as metamaterials with negative refraction index and solutions of Helmholtz' equation in paraxial approximation relevant for the description of laser beams. Chapter 5 describes non-Abelian gauge theories from a classical, geometric point of view, in analogy to Maxwell theory as a prototype, and culminates in an application to the U(2) theory relevant for electroweak interactions. The last chapter 6 gives a concise summary of semi-Riemannian geometry as the framework for the classical field theory of gravitation. The chapter concludes wit...

The Two-Dimensional Gabor Function Adapted to Natural Image Statistics: A Model of Simple-Cell Receptive Fields and Sparse Structure in Images.

Science.gov (United States)

Loxley, P N

2017-10-01

The two-dimensional Gabor function is adapted to natural image statistics, leading to a tractable probabilistic generative model that can be used to model simple cell receptive field profiles, or generate basis functions for sparse coding applications. Learning is found to be most pronounced in three Gabor function parameters representing the size and spatial frequency of the two-dimensional Gabor function and characterized by a nonuniform probability distribution with heavy tails. All three parameters are found to be strongly correlated, resulting in a basis of multiscale Gabor functions with similar aspect ratios and size-dependent spatial frequencies. A key finding is that the distribution of receptive-field sizes is scale invariant over a wide range of values, so there is no characteristic receptive field size selected by natural image statistics. The Gabor function aspect ratio is found to be approximately conserved by the learning rules and is therefore not well determined by natural image statistics. This allows for three distinct solutions: a basis of Gabor functions with sharp orientation resolution at the expense of spatial-frequency resolution, a basis of Gabor functions with sharp spatial-frequency resolution at the expense of orientation resolution, or a basis with unit aspect ratio. Arbitrary mixtures of all three cases are also possible. Two parameters controlling the shape of the marginal distributions in a probabilistic generative model fully account for all three solutions. The best-performing probabilistic generative model for sparse coding applications is found to be a gaussian copula with Pareto marginal probability density functions.

An introduction to extra dimensions

International Nuclear Information System (INIS)

Perez-Lorenzana, Abdel

2005-01-01

Models that involve extra dimensions have introduced completely new ways of looking up on old problems in theoretical physics. The aim of the present notes is to provide a brief introduction to the many uses that extra dimensions have found over the last few years, mainly following an effective field theory point of view. Most parts of the discussion are devoted to models with flat extra dimensions, covering both theoretical and phenomenological aspects. We also discuss some of the new ideas for model building where extra dimensions may play a role, including symmetry breaking by diverse new and old mechanisms. Some interesting applications of these ideas are discussed over the notes, including models for neutrino masses and proton stability. The last part of this review addresses some aspects of warped extra dimensions, and graviton localization

Large developing receptive fields using a distributed and locally reprogrammable address-event receiver.

Science.gov (United States)

Bamford, Simeon A; Murray, Alan F; Willshaw, David J

2010-02-01

A distributed and locally reprogrammable address-event receiver has been designed, in which incoming address-events are monitored simultaneously by all synapses, allowing for arbitrarily large axonal fan-out without reducing channel capacity. Synapses can change the address of their presynaptic neuron, allowing the distributed implementation of a biologically realistic learning rule, with both synapse formation and elimination (synaptic rewiring). Probabilistic synapse formation leads to topographic map development, made possible by a cross-chip current-mode calculation of Euclidean distance. As well as synaptic plasticity in rewiring, synapses change weights using a competitive Hebbian learning rule (spike-timing-dependent plasticity). The weight plasticity allows receptive fields to be modified based on spatio-temporal correlations in the inputs, and the rewiring plasticity allows these modifications to become embedded in the network topology.

Correspondence between classical and quantum chaos for hydrogen in a uniform magnetic field

Energy Technology Data Exchange (ETDEWEB)

Harada, A; Hasegawa, H [Kyoto Univ. (Japan). Dept. of Physics

1983-06-01

It is shown, by numerical computations, that the classical and the quantal critical energy of a hydrogen atom in a uniform magnetic field, characterising the onset of irregular motions, approximately coincide. This result is obtained by applying a simple scaling property of the classical Hamiltonian, valid only for Lsub(z)=O (the angular momentum component along the field vanishes), to the numerically deduced relative areas of the irregular region of Poincare surfaces of section.

Gauge bridges in classical field theory

International Nuclear Information System (INIS)

Jakobs, S.

2009-03-01

In this thesis Poisson structures of two classical gauge field theories (Maxwell-Klein-Gordon- and Maxwell-Dirac-system) are constructed using the parametrix construction of Green's functions. Parametrices for the Maxwell-Klein-Gordon- and Maxwell-Dirac-system are constructed in Minkowski space and this construction is later generalized to curved space times for the Maxwell-Klein-Gordon-system. With these Green's functions Poisson brackets will be defined as Peierls brackets. Finally non-local, gauge invariant observables, the so-called ''gauge bridges''are constructed. Gauge bridges are the matrix elements of holonomy operators. It is shown, that these emerge from Poisson brackets of local, gauge invariant observables. (orig.)

Quantum–classical correspondence of a field induced KAM-type ...

Indian Academy of Sciences (India)

WINTEC

Abstract. A transition from regular to chaotic behaviour in the dynamics of a classical Henon–Heiles oscillator in the presence of an external field is shown to have a similar quantum signature when studied using the pertaining phase portraits and the associated Kolmogorov–Sinai–Lyapunov entropies obtained through the ...

Quantum and classical correlations of intense beams of light investigated via joint photodetection

Energy Technology Data Exchange (ETDEWEB)

Agliati, Andrea [Quanta System S.p.A., Via IV Novembre, 116-21058, Solbiate Olona (Vatican City State, Holy See,) (Italy); Bondani, Maria [INFM/CNR, Unita di Como (Italy); Andreoni, Alessandra [Dipartimento di Fisica e Matematica, Universita degli Studi dell' Insubria, Como (Italy); Cillis, Giovanni De [Dipartimento di Fisica dell' Universita di Milano (Italy); Paris, Matteo G A [Dipartimento di Fisica dell' Universita di Milano (Italy)

2005-12-01

We address joint photodetection as a method for discriminating between the classical correlations of a thermal beam divided by a beam splitter and the quantum entanglement of a twin beam obtained by parametric down-conversion. We show that for intense beams of light the detection of the difference photocurrent may be used, in principle, in order to reveal entanglement, while the simple measurement of the correlation coefficient is not sufficient. We have experimentally measured the correlation coefficient and the variance of the difference photocurrent for several classical and quantum states. Results are in good agreement with theoretical predictions taking into account the extra noise in the generated fields that is due to the pump laser fluctuations.

Quantum and classical correlations of intense beams of light investigated via joint photodetection

International Nuclear Information System (INIS)

Agliati, Andrea; Bondani, Maria; Andreoni, Alessandra; Cillis, Giovanni De; Paris, Matteo G A

2005-01-01

We address joint photodetection as a method for discriminating between the classical correlations of a thermal beam divided by a beam splitter and the quantum entanglement of a twin beam obtained by parametric down-conversion. We show that for intense beams of light the detection of the difference photocurrent may be used, in principle, in order to reveal entanglement, while the simple measurement of the correlation coefficient is not sufficient. We have experimentally measured the correlation coefficient and the variance of the difference photocurrent for several classical and quantum states. Results are in good agreement with theoretical predictions taking into account the extra noise in the generated fields that is due to the pump laser fluctuations

Problems of generation and reception of gravitational waves. [Review

Energy Technology Data Exchange (ETDEWEB)

Pisarev, A F [Joint Inst. for Nuclear Research, Dubna (USSR)

1975-01-01

The present day status of the problems of gravitation, wave radiation and reception is surveyed. The physical presentation and mathematical description of the processes of radiation, propagation and interaction of gravitation waves with matter and the electromagnetic field are given. The experiments on the search for gravitation waves of astophysical nature are analysed. The laboratory and cosmic sources of these waves and the methods of their reception are described. Special attention is drawn to the analysis of the proposals to perform a complete laboratory gravitation wave experiment.

The classical field limit of scattering theory for non-relativistic many-boson systems. Pt. 1

International Nuclear Information System (INIS)

Ginibre, J.

1979-01-01

We study the classical field limit of non-relativistic many-boson theories in space dimension n >= 3. When h → 0, the correlation functions, which are the averages of products of bounded functions of field operators at different times taken in suitable states, converge to the corresponding functions of the appropriate solutions of the classical field equation, and the quantum fluctuations, are described by the equation obtained by linearizing the field equation around the classical solution. These properties were proved by Hepp for suitably regular potentials and in finite time intervals. Using a general theory of existence of global solutions and a general scattering theory for the clasical equation, we extend these results in two directions: (1) we consider more singular potentials, (2) more imortant, we prove that for dispersive classical solutions, the h → 0 limit is uniform in time in an appropriate representation of the field operators. As a consequence we obtain the convergence of suitable matrix elements of the wave operators and, if asymptotic completeness holds, of the S-matrix. (orig.) [de

Classical gluon fields and collective dynamics of color-charge systems

International Nuclear Information System (INIS)

Voronyuk, V.; Goloviznin, V. V.; Zinovjev, G. M.; Cassing, W.; Molodtsov, S. V.; Snigirev, A. M.; Toneev, V. D.

2015-01-01

An investigation of color fields that arise in collisions of relativistic heavy ions reveals that, in the non-Abelian case, a change in the color charge leads to the appearance of an extra term that generates a sizable contribution of color-charge glow in chromoelectric and chromomagnetic fields. The possibility of the appearance of a color echo in the scattering of composite color particles belonging to the dipole type is discussed. Arguments are adduced in support of the statement that such effects are of importance in simulating the first stage of ultrarelativistic heavy-ion collisions,where the initial parton state is determined by a high nonequilibrium parton density and by strong local color fluctuations

Anthropomorphism in the search for extra-terrestrial intelligence - The limits of cognition?

Science.gov (United States)

Bohlmann, Ulrike M.; Bürger, Moritz J. F.

2018-02-01

The question "Are we alone?" lingers in the human mind since ancient times. Early human civilisations populated the heavens above with a multitude of Gods endowed with some all too human characteristics - from their outer appearance to their innermost motivations. En passant they created thereby their own cultural founding myths on which they built their understanding of the world and its phenomena and deduced as well rules for the functioning of their own society. Advancing technology has enabled us to conduct this human quest for knowledge with more scientific means: optical and radio-wavelengths are being monitored for messages by an extra-terrestrial intelligence and active messaging attempts have also been undertaken. Scenarios have been developed for a possible detection of extra-terrestrial intelligence and post-detection guidelines and protocols have been elaborated. The human responses to the whole array of questions concerning the potential existence, discovery of and communication/interaction with an extra-terrestrial intelligence share as one clear thread a profound anthropomorphism, which ascribes classical human behavioural patterns also to an extra-terrestrial intelligence in much the same way as our ancestors attributed comparable conducts to mythological figures. This paper aims at pinpointing this thread in a number of classical reactions to basic questions related to the search for extra-terrestrial intelligence. Many of these reactions are based on human motives such as curiosity and fear, rationalised by experience and historical analogy and modelled in the Science Fiction Culture by literature and movies. Scrutinising the classical hypothetical explanations of the Fermi paradox under the angle of a potentially undue anthropomorphism, this paper intends to assist in understanding our human epistemological limitations in the search for extra-terrestrial intelligence. This attempt is structured into a series of questions: I. Can we be alone? II

Cavity quantum chromodynamics in the presence of a classical background field

International Nuclear Information System (INIS)

Gavin, E.J.O.; Viollier, R.D.

1988-01-01

The QCD (quantum chromodynamics) Lagrange density is constructed in which the gluon field has a classical part, using the background field gauge. The conserved currents deriving from the symmetries of this theory are given and used to define boundary conditions on the field operators on the surface of a spherical, static cavity. The field operators are expanded in terms of a complete set of cavity modes that satisfy the boundary conditions and the field equations in the Dirac picture. 13 refs

Bosonic Loop Diagrams as Perturbative Solutions of the Classical Field Equations in φ4-Theory

International Nuclear Information System (INIS)

Finster, Felix; Tolksdorf, Juergen

2012-01-01

Solutions of the classical φ 4 -theory in Minkowski space-time are analyzed in a perturbation expansion in the nonlinearity. Using the language of Feynman diagrams, the solution of the Cauchy problem is expressed in terms of tree diagrams which involve the retarded Green's function and have one outgoing leg. In order to obtain general tree diagrams, we set up a ''classical measurement process'' in which a virtual observer of a scattering experiment modifies the field and detects suitable energy differences. By adding a classical stochastic background field, we even obtain all loop diagrams. The expansions are compared with the standard Feynman diagrams of the corresponding quantum field theory.

Bosonic Loop Diagrams as Perturbative Solutions of the Classical Field Equations in ϕ4-Theory

Science.gov (United States)

Finster, Felix; Tolksdorf, Jürgen

2012-05-01

Solutions of the classical ϕ4-theory in Minkowski space-time are analyzed in a perturbation expansion in the nonlinearity. Using the language of Feynman diagrams, the solution of the Cauchy problem is expressed in terms of tree diagrams which involve the retarded Green's function and have one outgoing leg. In order to obtain general tree diagrams, we set up a "classical measurement process" in which a virtual observer of a scattering experiment modifies the field and detects suitable energy differences. By adding a classical stochastic background field, we even obtain all loop diagrams. The expansions are compared with the standard Feynman diagrams of the corresponding quantum field theory.

Anyons as spin particles: from classical mechanics to field theory

OpenAIRE

Plyushchay, Mikhail S.

1995-01-01

(2+1)-dimensional relativistic fractional spin particles are considered within the framework of the group-theoretical approach to anyons starting from the level of classical mechanics and concluding by the construction of the minimal set of linear differential field equations.

Classical electromagnetic field theory in the presence of magnetic sources

OpenAIRE

Chen, Wen-Jun; Li, Kang; Naón, Carlos

2001-01-01

Using two new well defined 4-dimensional potential vectors, we formulate the classical Maxwell's field theory in a form which has manifest Lorentz covariance and SO(2) duality symmetry in the presence of magnetic sources. We set up a consistent Lagrangian for the theory. Then from the action principle we get both Maxwell's equation and the equation of motion of a dyon moving in the electro-magnetic field.

Classical field theory. On electrodynamics, non-Abelian gauge theories and gravitation. 2. ed.

Energy Technology Data Exchange (ETDEWEB)

Scheck, Florian

2018-04-01

Scheck's successful textbook presents a comprehensive treatment, ideally suited for a one-semester course. The textbook describes Maxwell's equations first in their integral, directly testable form, then moves on to their local formulation. The first two chapters cover all essential properties of Maxwell's equations, including their symmetries and their covariance in a modern notation. Chapter 3 is devoted to Maxwell's theory as a classical field theory and to solutions of the wave equation. Chapter 4 deals with important applications of Maxwell's theory. It includes topical subjects such as metamaterials with negative refraction index and solutions of Helmholtz' equation in paraxial approximation relevant for the description of laser beams. Chapter 5 describes non-Abelian gauge theories from a classical, geometric point of view, in analogy to Maxwell's theory as a prototype, and culminates in an application to the U(2) theory relevant for electroweak interactions. The last chapter 6 gives a concise summary of semi-Riemannian geometry as the framework for the classical field theory of gravitation. The chapter concludes with a discussion of the Schwarzschild solution of Einstein's equations and the classical tests of general relativity. The new concept of this edition presents the content divided into two tracks: the fast track for master's students, providing the essentials, and the intensive track for all wanting to get in depth knowledge of the field. Cleary labeled material and sections guide students through the preferred level of treatment. Numerous problems and worked examples will provide successful access to Classical Field Theory.

Classical, Semi-classical and Quantum Noise

CERN Document Server

Poor, H; Scully, Marlan

2012-01-01

David Middleton was a towering figure of 20th Century engineering and science and one of the founders of statistical communication theory. During the second World War, the young David Middleton, working with Van Fleck, devised the notion of the matched filter, which is the most basic method used for detecting signals in noise. Over the intervening six decades, the contributions of Middleton have become classics. This collection of essays by leading scientists, engineers and colleagues of David are in his honor and reflect the wide  influence that he has had on many fields. Also included is the introduction by Middleton to his forthcoming book, which gives a wonderful view of the field of communication, its history and his own views on the field that he developed over the past 60 years. Focusing on classical noise modeling and applications, Classical, Semi-Classical and Quantum Noise includes coverage of statistical communication theory, non-stationary noise, molecular footprints, noise suppression, Quantum e...

On the Lie symmetry group for classical fields in noncommutative space

Energy Technology Data Exchange (ETDEWEB)

Pereira, Ricardo Martinho Lima Santiago [Universidade Federal da Bahia (UFBA), BA (Brazil); Instituto Federal da Bahia (IFBA), BA (Brazil); Ressureicao, Caio G. da [Universidade Federal da Bahia (UFBA), BA (Brazil). Inst. de Fisica; Vianna, Jose David M. [Universidade Federal da Bahia (UFBA), BA (Brazil); Universidade de Brasilia (UnB), DF (Brazil)

2011-07-01

Full text: An alternative way to include effects of noncommutative geometries in field theory is based on the concept of noncommutativity among degrees of freedom of the studied system. In this context it is reasonable to consider that, in the multiparticle noncommutative quantum mechanics (NCQM), the noncommutativity among degrees of freedom to discrete system with N particles is also verified. Further, an analysis of the classical limit of the single particle NCQM leads to a deformed Newtonian mechanics where the Newton's second law is modified in order to include the noncommutative parameter {theta}{sub {iota}j} and, for a one-dimensional discrete system with N particles, the dynamical evolution of each particle is given by this modified Newton's second law. Hence, applying the continuous limit to this multiparticle classical system it is possible to obtain a noncommutative extension of two -dimensional field theory in a noncommutative space. In the present communication we consider a noncommutative extension of the scalar field obtained from this approach and we analyze the Lie symmetries in order to compare the Lie group of this field with the usual scalar field in the commutative space. (author)

Rydberg atoms in circular polarization: Classical stabilization in optical frequency fields

International Nuclear Information System (INIS)

Chism, Will; Reichl, L.E.

2002-01-01

We investigate the classical dynamics of the Rydberg atom in circularly polarized laser fields, restricted to the two-dimensional plane of polarization. We use a Poincare surface of section to study nonlinear resonance structures for optical frequency driving fields. We demonstrate the existence and morphology of these structures as the laser intensity transitions from moderate to intense

CKM pattern from localized generations in extra dimension

International Nuclear Information System (INIS)

Matti, C.

2006-01-01

We revisit the issue of the quark masses and mixing angles in the framework of large extra dimension. We consider three identical standard model families resulting from higher-dimensional fields localized on different branes embedded in a large extra dimension. Furthermore we use a decaying profile in the bulk different form previous works. With the Higgs field also localized on a different brane, the hierarchy of masses between the families results from their different positions in the extra space. When the left-handed doublet and the right-handed singlets are localized with different couplings on the branes, we found a set of brane locations in one extra dimension which leads to the correct quark masses and mixing angles with the sufficient strength of CP-violation. We see that the decaying profile of the Higgs field plays a crucial role for producing the hierarchies in a rather natural way. (orig.)

Reception research 2.0

DEFF Research Database (Denmark)

Mathieu, David

Some might argue that reception analysis is a remnant of the past in an age where “people formerly known as the audience” (Rosen, 2006) are producing and circulating content on a diversity of interactive and participatory media platforms. Far from being the case, reception research must continue......, which appears increasingly complex, multi-formed and integrated to the audience. The original dimensions of Schrøder’s model need to be looked at with reference to both reception and circulation (Jenkins et al., 2013), and to the network that binds participatory media culture. It appears that with media...... 2.0, phenomena which traditionally fell under the labels of interpretation or reception are increasingly taking part in the media text itself. As audiences become textual matters, they contribute to set a new agenda for media research....

The Anion Paradox in Sodium Taste Reception: Resolution by Voltage-Clamp Studies

Science.gov (United States)

Ye, Qing; Heck, Gerard L.; Desimone, John A.

1991-11-01

Sodium salts are potent taste stimuli, but their effectiveness is markedly dependent on the anion, with chloride yielding the greatest response. The cellular mechanisms that mediate this phenomenon are not known. This "anion paradox" has been resolved by considering the field potential that is generated by restricted electrodiffusion of the anion through paracellular shunts between taste-bud cells. Neural responses to sodium chloride, sodium acetate, and sodium gluconate were studied while the field potential was voltage-clamped. Clamping at electronegative values eliminated the anion effect, whereas clamping at electropositive potentials exaggerated it. Thus, field potentials across the lingual epithelium modulate taste reception, indicating that the functional unit of taste reception includes the taste cell and its paracellular microenvironment.

Quasiperiodical orbits in the scalar classical lambdaphi4 field theory

International Nuclear Information System (INIS)

Belova, T.I.; Kudryavtsev, A.E.

1985-01-01

New numerical and theoretical results of resonance kink-antikink (Kanti K) interactions in the classical one-dimentional space Higgs theory are presented. Earlier studies of these interactions revealed nine initial relative velocity-intervals with two-bounce Kanti K-collisions followed by the escape of kinks to infinite separations, the breathing solution was formed outside those intervals. Two-bounce Kanti K-interactions with the number of small oscillations between Kanti K-bounces up to 35 in the initial kink velocity interval 0.18 <= Vsub(infinite) <= 0.26 were found. Several examples for n-bounces Kanti K-interaction (n <= 6) are also found. The observed phenomenon can be explaned by the existence of quasi-two-periodical solutions of the nonlinear wave equation. The simple Hamiltonian with two degrees of freedom is studied. This model supplies quantitative descrtiptions of all numerical results for the field theory considered above. The considered phenomenon may be called ''autoquantization'' of a nonlinear classical scalar selfinteracting field

Eliminating Glutamatergic Input onto Horizontal Cells Changes the Dynamic Range and Receptive Field Organization of Mouse Retinal Ganglion Cells.

Science.gov (United States)

Ströh, Sebastian; Puller, Christian; Swirski, Sebastian; Hölzel, Maj-Britt; van der Linde, Lea I S; Segelken, Jasmin; Schultz, Konrad; Block, Christoph; Monyer, Hannah; Willecke, Klaus; Weiler, Reto; Greschner, Martin; Janssen-Bienhold, Ulrike; Dedek, Karin

2018-02-21

In the mammalian retina, horizontal cells receive glutamatergic inputs from many rod and cone photoreceptors and return feedback signals to them, thereby changing photoreceptor glutamate release in a light-dependent manner. Horizontal cells also provide feedforward signals to bipolar cells. It is unclear, however, how horizontal cell signals also affect the temporal, spatial, and contrast tuning in retinal output neurons, the ganglion cells. To study this, we generated a genetically modified mouse line in which we eliminated the light dependency of feedback by deleting glutamate receptors from mouse horizontal cells. This genetic modification allowed us to investigate the impact of horizontal cells on ganglion cell signaling independent of the actual mode of feedback in the outer retina and without pharmacological manipulation of signal transmission. In control and genetically modified mice (both sexes), we recorded the light responses of transient OFF-α retinal ganglion cells in the intact retina. Excitatory postsynaptic currents (EPSCs) were reduced and the cells were tuned to lower temporal frequencies and higher contrasts, presumably because photoreceptor output was attenuated. Moreover, receptive fields of recorded cells showed a significantly altered surround structure. Our data thus suggest that horizontal cells are responsible for adjusting the dynamic range of retinal ganglion cells and, together with amacrine cells, contribute to the center/surround organization of ganglion cell receptive fields in the mouse. SIGNIFICANCE STATEMENT Horizontal cells represent a major neuronal class in the mammalian retina and provide lateral feedback and feedforward signals to photoreceptors and bipolar cells, respectively. The mode of signal transmission remains controversial and, moreover, the contribution of horizontal cells to visual processing is still elusive. To address the question of how horizontal cells affect retinal output signals, we recorded the light

Gauge-fields and integrated quantum-classical theory

International Nuclear Information System (INIS)

Stapp, H.P.

1986-01-01

Physical situations in which quantum systems communicate continuously to their classically described environment are not covered by contemporary quantum theory, which requires a temporary separation of quantum degrees of freedom from classical ones. A generalization would be needed to cover these situations. An incomplete proposal is advanced for combining the quantum and classical degrees of freedom into a unified objective description. It is based on the use of certain quantum-classical structures of light that arise from gauge invariance to coordinate the quantum and classical degrees of freedom. Also discussed is the question of where experimenters should look to find phenomena pertaining to the quantum-classical connection. 17 refs

Classical and quantum mechanical studies of HF in an intense laser field

International Nuclear Information System (INIS)

Dardi, P.S.; Gray, S.K.

1982-01-01

The behavior of an HF molecule in an intense laser field is investigated with both classical trajectories and quantum dynamics. Vibration-rotation transition probabilities and energy absorption as a function of laser pulse time are calculated for the diatomic initially in its ground state. For comparison, results are also reported for a model nonrotating HF molecule. It is found that classical mechanics does not predict the correct time behavior of the system, nor does it predict the correct rotational state distributions. Classical mechanics does, however, predict pulse time averaged quantities to be the correct order of magnitude. There is also a correct general trend of increased multiphoton excitation for laser frequencies red-shifted from the one-photon resonance, although multiphoton resonance peaks are not observed in the classical results and far too little multiphoton excitation is predicted. The effect of laser phase has also been investigated and shown to be relatively unimportant in both the classical and quantum dynamics

An examination of the concept of driving point receptance

Science.gov (United States)

Sheng, X.; He, Y.; Zhong, T.

2018-04-01

In the field of vibration, driving point receptance is a well-established and widely applied concept. However, as demonstrated in this paper, when a driving point receptance is calculated using the finite element (FE) method with solid elements, it does not converge as the FE mesh becomes finer, suggesting that there is a singularity. Hence, the concept of driving point receptance deserves a rigorous examination. In this paper, it is firstly shown that, for a point harmonic force applied on the surface of an elastic half-space, the Boussinesq formula can be applied to calculate the displacement amplitude of the surface if the response point is sufficiently close to the load. Secondly, by applying the Betti reciprocal theorem, it is shown that the displacement of an elastic body near a point harmonic force can be decomposed into two parts, with the first one being the displacement of an elastic half-space. This decomposition is useful, since it provides a solid basis for the introduction of a contact spring between a wheel and a rail in interaction. However, according to the Boussinesq formula, this decomposition also leads to the conclusion that a driving point receptance is infinite (singular), and would be undefinable. Nevertheless, driving point receptances have been calculated using different methods. Since the singularity identified in this paper was not appreciated, no account was given to the singularity in these calculations. Thus, the validity of these calculation methods must be examined. This constructs the third part of the paper. As the final development of the paper, the above decomposition is utilised to define and determine driving point receptances required for dealing with wheel/rail interactions.

Inflation from periodic extra dimensions

Energy Technology Data Exchange (ETDEWEB)

Higaki, Tetsutaro [Department of Physics, Keio University, Kanagawa 223-8522 (Japan); Tatsuta, Yoshiyuki, E-mail: thigaki@rk.phys.keio.ac.jp, E-mail: y_tatsuta@akane.waseda.jp [Department of Physics, Waseda University, Tokyo 169-8555 (Japan)

2017-07-01

We discuss a realization of a small field inflation based on string inspired supergravities. In theories accompanying extra dimensions, compactification of them with small radii is required for realistic situations. Since the extra dimension can have a periodicity, there will appear (quasi-)periodic functions under transformations of moduli of the extra dimensions in low energy scales. Such a periodic property can lead to a UV completion of so-called multi-natural inflation model where inflaton potential consists of a sum of multiple sinusoidal functions with a decay constant smaller than the Planck scale. As an illustration, we construct a SUSY breaking model, and then show that such an inflaton potential can be generated by a sum of world sheet instantons in intersecting brane models on extra dimensions containing orbifold. We show also predictions of cosmic observables by numerical analyzes.

Classically integrable boundary conditions for affine Toda field theories

International Nuclear Information System (INIS)

Bowcock, P.; Corrigan, E.; Dorey, P.E.; Rietdijk, R.H.

1995-01-01

Boundary conditions compatible with classical integrability are studied both directly, using an approach based on the explicit construction of conserved quantities, and indirectly by first developing a generalisation of the Lax pair idea. The latter approach is closer to the spirit of earlier work by Sklyanin and yields a complete set of conjectures for permissible boundary conditions for any affine Toda field theory. (orig.)

Geometry of Lagrangian first-order classical field theories

International Nuclear Information System (INIS)

Echeverria-Enriquez, A.; Munoz-Lecanda, M.C.; Roman-Roy, N.

1996-01-01

We construct a lagrangian geometric formulation for first-order field theories using the canonical structures of first-order jet bundles, which are taken as the phase spaces of the systems in consideration. First of all, we construct all the geometric structures associated with a first-order jet bundle and, using them, we develop the lagrangian formalism, defining the canonical forms associated with a lagrangian density and the density of lagrangian energy, obtaining the Euler-Lagrange equations in two equivalent ways: as the result of a variational problem and developing the jet field formalism (which is a formulation more similar to the case of mechanical systems). A statement and proof of Noether's theorem is also given, using the latter formalism. Finally, some classical examples are briefly studied. (orig.)

Classical behavior of a scalar field in the inflationary universe

International Nuclear Information System (INIS)

Sasaki, Misao; Nambu, Yasusada; Nakao, Ken-ichi.

1987-09-01

Extending the coarse-graining approach of Starobinsky, we formulate a theory to deal with the dynamics of a scalar field in inflationary universe models. We find a set of classical Langevin equations which describes the large scale behavior of the scalar field, provided that the coarse-grained size is greater than the effective compton wavelength of the scalar field. The corresponding Fokker-Planck equation is also derived which is defined on the phase space of the scalar field. We show that our theory is essentially equivalent to the one-loop field theory in de Sitter space and reduces to that of Starobinsky in a strong limit of the slow roll-over condition. Analysis of a simple Higgs potential model is done and the implications are discussed. (author)

Receptive processer og IT

DEFF Research Database (Denmark)

Ambjørn, Lone

2002-01-01

Sproglæringsteoretisk værktøj til udvikling af IT-støttede materialer og programmer inden for sproglig reception......Sproglæringsteoretisk værktøj til udvikling af IT-støttede materialer og programmer inden for sproglig reception...

Mean-field approximation for spacing distribution functions in classical systems

Science.gov (United States)

González, Diego Luis; Pimpinelli, Alberto; Einstein, T. L.

2012-01-01

We propose a mean-field method to calculate approximately the spacing distribution functions p(n)(s) in one-dimensional classical many-particle systems. We compare our method with two other commonly used methods, the independent interval approximation and the extended Wigner surmise. In our mean-field approach, p(n)(s) is calculated from a set of Langevin equations, which are decoupled by using a mean-field approximation. We find that in spite of its simplicity, the mean-field approximation provides good results in several systems. We offer many examples illustrating that the three previously mentioned methods give a reasonable description of the statistical behavior of the system. The physical interpretation of each method is also discussed.

Invocation Receptivity in Female of Rabbit

Directory of Open Access Journals (Sweden)

Martin Fik

2017-05-01

Full Text Available The target of this work was verified effect of transport females in the car for advance state of receptivity in young females broiler rabbits. We used nulliparous females of broiler hybrid HYCOLE (age 4-5 months, weight 3.5-3.8 kg. Experiment was realizated twice. First in half of November (31 females, second in half of February (32 females. Females was layed individually in boxes. After they were transported by car 1 hour (50 km. Before and after experiment we detected state of receptivity in females with coloration of vulva. The state of receptivity was determited from 1 for 4 colour of vulva. ( 1 – anemic coloration of vulva, 2- pink, 3 – red, 4- violet. We detected positive state of transport, on the receptivity. In November before transport was average of receptivity 1.87, after transport 2.25. The state of receptivity will be improve in 12 females (38.71 %. Improve from 1 to 2 was detected in 4 females, from 2 to 3 in 8 females. Improved from 2 to 4 , or from 3 to 4 wasn´t noticed in this group. The state of receptivity wasn´t changed in 19 females (61.29 %. In the state of receptivity 1 stayed 2 females, in the state 2 stayed 15 females, in the state 3 stayed 2 females and in the state 4 wasn´t any female. In February after the end of experiment, state of receptivity was improved with transport in the car from 2.19 to 2.65. The state of receptivity was improved in 13 females  (40.63 %.  Improve from 1 to 2 we detected in 1 female, from 2 to 3 we detected in 8 females, from 2 to 4 we detected in 2 females, from 3 to 4 in 2 females. In 19 females (59.38% we don´t noticed change state of receptivity. In the state of receptivity 1 were 2 females, in 2 were 11 females, in 3 were 5 females, in 4 was 1 female.

Rovibrational dynamics of the RbCs molecule in static electric fields. Classical study

Energy Technology Data Exchange (ETDEWEB)

Arnaiz, Pedro F.; Iñarrea, Manuel [Área de Física, Universidad de la Rioja, E-26006 Logroño (Spain); Salas, J. Pablo, E-mail: josepablo.salas@unirioja.es [Área de Física, Universidad de la Rioja, E-26006 Logroño (Spain)

2012-04-02

We study the classical dynamics of the RbCs molecule in the presence of a static electric field. Under the Born–Oppenheimer approximation, we perform a rovibrational investigation which includes the interaction of the field with the molecular polarizability. The stability of the equilibrium points and the phase space structure of the system are explored in detail. We find that, for strong electric fields or for energies close to the dissociation threshold, the molecular polarizability causes relevant effects on the system dynamics. -- Highlights: ► We study the classical rovibrational dynamics of the alkali polar dimer RbCs. ► In the model we consider the interaction of the field with the molecular polarizability. ► The potential energy surface is studied depending on the electric field strength. ► Using surfaces of section we study the phase space structure. ► We find that the molecular polarizability causes relevant effects on the system dynamics.

Rovibrational dynamics of the RbCs molecule in static electric fields. Classical study

International Nuclear Information System (INIS)

Arnaiz, Pedro F.; Iñarrea, Manuel; Salas, J. Pablo

2012-01-01

We study the classical dynamics of the RbCs molecule in the presence of a static electric field. Under the Born–Oppenheimer approximation, we perform a rovibrational investigation which includes the interaction of the field with the molecular polarizability. The stability of the equilibrium points and the phase space structure of the system are explored in detail. We find that, for strong electric fields or for energies close to the dissociation threshold, the molecular polarizability causes relevant effects on the system dynamics. -- Highlights: ► We study the classical rovibrational dynamics of the alkali polar dimer RbCs. ► In the model we consider the interaction of the field with the molecular polarizability. ► The potential energy surface is studied depending on the electric field strength. ► Using surfaces of section we study the phase space structure. ► We find that the molecular polarizability causes relevant effects on the system dynamics.

Extra-Required Service: A Radical Shift in Frontline Geriatric Caregiving

Science.gov (United States)

Clarke, Egerton

2011-01-01

Much research examines the professional nursing practices of traditional and modern caregivers, but it remains unclear whether the delivery of extra-required services is diminished as the caregiver moves from traditional to modern community. Building on the classical works of sociologists Ferdinand Tonnies, Max Weber, and Emile Durkheim, this…

On the construction of classical superstring field theories

Energy Technology Data Exchange (ETDEWEB)

Konopka, Sebastian Johann Hermann

2016-07-01

This thesis describes the construction of classical superstring field theories based on the small Hilbert space. First we describe the traditional construction of perturbative superstring theory as an integral over the supermoduli space of type II world sheets. The geometry of supermoduli space dictates many algebraic properties of the string field theory action. In particular it allows for an algebraisation of the construction problem for classical superstring field theories in terms of homotopy algebras. Next, we solve the construction problem for open superstrings based on Witten's star product. The construction is recursive and involves a choice of homotopy operator for the zero mode of the η-ghost. It turns out that the solution can be extended to the Neveu-Schwarz subsectors of all superstring field theories. The recursive construction involves a hierarchy of string products at various picture deficits. The construction is not entirely natural, but it is argued that different choices give rise to solutions related by a field redefinition. Due to the presence of odd gluing parameters for Ramond states the extension to full superstring field theory is non-trivial. Instead, we construct gauge-invariant equations of motion for all superstring field theories. The realisation of spacetime supersymmetry in the open string sector is highly non-trivial and is described explicitly for the solution based on Witten's star product. After a field redefinition the non-polynomial equations of motion and the small Hilbert space constraint become polynomial. This polynomial system is shown to be supersymmetric. Quite interestingly, the supersymmetry algebra closes only up to gauge transformations. This indicates that only the physical phase space realizes N=1 supersymmetry. Apart from the algebraic constraints dictated by the geometry of supermoduli space the equations of motion or action should reproduce the traditional string S-matrix. The S-matrix of a field

Measuring receptive collocational competence across proficiency ...

African Journals Online (AJOL)

The present study investigates (i) English as Foreign Language (EFL) learners' receptive collocational knowledge growth in relation to their linguistic proficiency level; (ii) how much receptive collocational knowledge is acquired as linguistic proficiency develops; and (iii) the extent to which receptive knowledge of ...

Geometry of Lagrangian first-order classical field theories

Energy Technology Data Exchange (ETDEWEB)

Echeverria-Enriquez, A. [Univ. Politecnica de Cataluna, Barcelona (Spain). Departamento de Matematica Aplicada y Telematica; Munoz-Lecanda, M.C. [Univ. Politecnica de Cataluna, Barcelona (Spain). Departamento de Matematica Aplicada y Telematica; Roman-Roy, N. [Univ. Politecnica de Cataluna, Barcelona (Spain). Departamento de Matematica Aplicada y Telematica

1996-10-01

We construct a lagrangian geometric formulation for first-order field theories using the canonical structures of first-order jet bundles, which are taken as the phase spaces of the systems in consideration. First of all, we construct all the geometric structures associated with a first-order jet bundle and, using them, we develop the lagrangian formalism, defining the canonical forms associated with a lagrangian density and the density of lagrangian energy, obtaining the Euler-Lagrange equations in two equivalent ways: as the result of a variational problem and developing the jet field formalism (which is a formulation more similar to the case of mechanical systems). A statement and proof of Noether`s theorem is also given, using the latter formalism. Finally, some classical examples are briefly studied. (orig.)

Plasmon mass scale and quantum fluctuations of classical fields on a real time lattice

Science.gov (United States)

Kurkela, Aleksi; Lappi, Tuomas; Peuron, Jarkko

2018-03-01

Classical real-time lattice simulations play an important role in understanding non-equilibrium phenomena in gauge theories and are used in particular to model the prethermal evolution of heavy-ion collisions. Above the Debye scale the classical Yang-Mills (CYM) theory can be matched smoothly to kinetic theory. First we study the limits of the quasiparticle picture of the CYM fields by determining the plasmon mass of the system using 3 different methods. Then we argue that one needs a numerical calculation of a system of classical gauge fields and small linearized fluctuations, which correspond to quantum fluctuations, in a way that keeps the separation between the two manifest. We demonstrate and test an implementation of an algorithm with the linearized fluctuation showing that the linearization indeed works and that the Gauss's law is conserved.

Cortical depth dependent population receptive field attraction by spatial attention in human V1.

Science.gov (United States)

Klein, Barrie P; Fracasso, Alessio; van Dijk, Jelle A; Paffen, Chris L E; Te Pas, Susan F; Dumoulin, Serge O

2018-04-27

Visual spatial attention concentrates neural resources at the attended location. Recently, we demonstrated that voluntary spatial attention attracts population receptive fields (pRFs) toward its location throughout the visual hierarchy. Theoretically, both a feed forward or feedback mechanism could underlie pRF attraction in a given cortical area. Here, we use sub-millimeter ultra-high field functional MRI to measure pRF attraction across cortical depth and assess the contribution of feed forward and feedback signals to pRF attraction. In line with previous findings, we find consistent attraction of pRFs with voluntary spatial attention in V1. When assessed as a function of cortical depth, we find pRF attraction in every cortical portion (deep, center and superficial), although the attraction is strongest in deep cortical portions (near the gray-white matter boundary). Following the organization of feed forward and feedback processing across V1, we speculate that a mixture of feed forward and feedback processing underlies pRF attraction in V1. Specifically, we propose that feedback processing contributes to the pRF attraction in deep cortical portions. Copyright © 2018. Published by Elsevier Inc.

On the classical origins of yangian symmetry in integrable field theory

International Nuclear Information System (INIS)

MacKay, N.J.

1992-01-01

We show that Drinfeld's yangian algebra, studied recently as the algebra of conserved charges in certain two-dimensional integrable quantum field theories, is also present in the classical theory as a Poisson-Hopf algebra, and exhibit explicitly the Serre relations, coproduct and antipode. (orig.)

Critical behavior in a random field classical Heisenberg model for amorphous systems

International Nuclear Information System (INIS)

Albuquerque, Douglas F. de; Alves, Sandro Roberto L.; Arruda, Alberto S. de

2005-01-01

By using the differential operator technique and the effective field theory scheme, the critical behavior of amorphous classical Heisenberg ferromagnet of spin-1/2 in a random field is studied. The phase diagram in the T-H and T-α planes on a simple cubic lattice for a cluster with two spins is obtained. Tricritical points, reentrant phenomena and influence of the random field and amorphization on the transition temperature are discussed

Lower Bound on the Energy Density in Classical and Quantum Field Theories.

Science.gov (United States)

Wall, Aron C

2017-04-14

A novel method for deriving energy conditions in stable field theories is described. In a local classical theory with one spatial dimension, a local energy condition always exists. For a relativistic field theory, one obtains the dominant energy condition. In a quantum field theory, there instead exists a quantum energy condition, i.e., a lower bound on the energy density that depends on information-theoretic quantities. Some extensions to higher dimensions are briefly discussed.

Classical origins of stabilization in circularly polarized laser fields

International Nuclear Information System (INIS)

Chism, Will; Choi, Dae-Il; Reichl, L. E.

2000-01-01

We investigate the interaction of a two-dimensional model atom with an intense, high-frequency circularly polarized laser pulse. As the laser intensity is increased, the ionization rate initially increases, then decreases dramatically, with the electron wave function developing an asymmetric ring form which rotates with the electric field. We provide evidence that this wave form is due to localization of the electron onto nonlinear classical structures. (c) 2000 The American Physical Society

Classical emergence of intrinsic spin-orbit interaction of light at the nanoscale

Science.gov (United States)

Vázquez-Lozano, J. Enrique; Martínez, Alejandro

2018-03-01

Traditionally, in macroscopic geometrical optics intrinsic polarization and spatial degrees of freedom of light can be treated independently. However, at the subwavelength scale these properties appear to be coupled together, giving rise to the spin-orbit interaction (SOI) of light. In this work we address theoretically the classical emergence of the optical SOI at the nanoscale. By means of a full-vector analysis involving spherical vector waves we show that the spin-orbit factorizability condition, accounting for the mutual influence between the amplitude (spin) and phase (orbit), is fulfilled only in the far-field limit. On the other side, in the near-field region, an additional relative phase introduces an extra term that hinders the factorization and reveals an intricate dynamical behavior according to the SOI regime. As a result, we find a suitable theoretical framework able to capture analytically the main features of intrinsic SOI of light. Besides allowing for a better understanding into the mechanism leading to its classical emergence at the nanoscale, our approach may be useful to design experimental setups that enhance the response of SOI-based effects.

Bruce X Longwood television reception survey

International Nuclear Information System (INIS)

Hatanaka, G.K.

1992-01-01

Property owners living close to a proposed 500-kV transmission line route in Ontario expressed concerns that the line would affect their television reception. To give a reasonable evaluation of the impact of the transmission line, tests were conducted before and after installation of the line in which the possibility of active or passive interference to reception was assessed. Measurements were made of signal strength and ambient noise, and television reception was also recorded on videotape. Possible transmission line effects due to radiated noise, signal reduction, and ghosts are analyzed. The analysis of signal and noise conditions, and the assessment of videotaped reception, provide reasonable evidence that the line has had negligible impact on the television reception along the line route. 13 refs., 18 figs., 12 tabs

New classical inversion formulas for centrosymmetric electric and magnetic fields; focusing potentials

International Nuclear Information System (INIS)

Bogdanov, I.V.; Demkov, Y.N.

1982-01-01

New inversion formulas are obtained for the classical scattering of a charged particle by a spherical or axisymmetric electric or magnetic field at a fixed impact parameter or angular momentum. For different cases, focusing fields are obtained similar to those previously considered for scattering by an electric field at a given energy, viz., of the backscattering (cat's eye), Maxwell fish eye, or Luneberg lens type. A magnetoelectric analogy is formulated, namely the existence of equivalent axisymmetric electric and magnetic fields that scatter charged particles in identical fashion

Plasmon mass scale and quantum fluctuations of classical fields on a real time lattice

Directory of Open Access Journals (Sweden)

Kurkela Aleksi

2018-01-01

Full Text Available Classical real-time lattice simulations play an important role in understanding non-equilibrium phenomena in gauge theories and are used in particular to model the prethermal evolution of heavy-ion collisions. Above the Debye scale the classical Yang-Mills (CYM theory can be matched smoothly to kinetic theory. First we study the limits of the quasiparticle picture of the CYM fields by determining the plasmon mass of the system using 3 different methods. Then we argue that one needs a numerical calculation of a system of classical gauge fields and small linearized fluctuations, which correspond to quantum fluctuations, in a way that keeps the separation between the two manifest. We demonstrate and test an implementation of an algorithm with the linearized fluctuation showing that the linearization indeed works and that the Gauss’s law is conserved.

Differential receptive field organizations give rise to nearly identical neural correlations across three parallel sensory maps in weakly electric fish.

Science.gov (United States)

Hofmann, Volker; Chacron, Maurice J

2017-09-01

Understanding how neural populations encode sensory information thereby leading to perception and behavior (i.e., the neural code) remains an important problem in neuroscience. When investigating the neural code, one must take into account the fact that neural activities are not independent but are actually correlated with one another. Such correlations are seen ubiquitously and have a strong impact on neural coding. Here we investigated how differences in the antagonistic center-surround receptive field (RF) organization across three parallel sensory maps influence correlations between the activities of electrosensory pyramidal neurons. Using a model based on known anatomical differences in receptive field center size and overlap, we initially predicted large differences in correlated activity across the maps. However, in vivo electrophysiological recordings showed that, contrary to modeling predictions, electrosensory pyramidal neurons across all three segments displayed nearly identical correlations. To explain this surprising result, we incorporated the effects of RF surround in our model. By systematically varying both the RF surround gain and size relative to that of the RF center, we found that multiple RF structures gave rise to similar levels of correlation. In particular, incorporating known physiological differences in RF structure between the three maps in our model gave rise to similar levels of correlation. Our results show that RF center overlap alone does not determine correlations which has important implications for understanding how RF structure influences correlated neural activity.

Extra force and extra mass from non-compact Kaluza-Klein theory in a cosmological model

International Nuclear Information System (INIS)

MadrizAguilar, J.E.; Bellini, M.

2005-01-01

Using the Hamilton-Jacobi formalism, we study extra force and extra mass in a recently introduced non-compact Kaluza-Klein cosmological model. We examine the inertial 4D mass m 0 of the inflaton field on a 4D FRW bulk in two examples. We find that m 0 has a geometrical origin and antigravitational effects on a non-inertial 4D bulk should be a consequence of the motion of the fifth coordinate with respect to the 4D bulk. (orig.)

Experimental Bell violations with classical, non-entangled optical fields

Science.gov (United States)

Gonzales, J.; Sánchez, P.; Barberena, D.; Yugra, Y.; Caballero, R.; De Zela, F.

2018-02-01

We report experiments in which the Bell parameter S that enters the Clauser-Horne-Shimony-Holt inequality: | S| ≤slant 2, attains values | S| > 2. In our experiments, we used two spatially separated optical beams, the electric fields of which were correlated to one another. The amount of correlation was quantified by the spectral degree of coherence η (α ,β ). This quantity measures the correlation between fields that exist at two distant locations and whose respective polarizations are given in terms of angles α and β, which can be set independently from one another. Such a correlation qualifies for the construction of the Bell parameter S. By changing the amount of field correlation, we could cover a range that goes from | S| 2. Our experimental findings should provide useful material for the ongoing, theoretical discussions about the quantum-classical border.

Confusion-limited galaxy fields. II. Classical analyses

International Nuclear Information System (INIS)

Chokshi, A.; Wright, E.L.

1989-01-01

Chokshi and Wright presented a detailed model for simulating angular distribution of galaxy images in fields that extended to very high redshifts. Standard tools are used to analyze these simulated galaxy fields for the Omega(O) = 0 and the Omega(O) = 1 cases in order to test the discriminatory power of these tools. Classical number-magnitude diagrams and surface brightness-color-color diagrams are employed to study crowded galaxy fields. An attempt is made to separate the effects due to stellar evolution in galaxies from those due to the space time geometry. The results show that this discrimination is maximized at near-infrared wavelengths where the stellar photospheres are still visible but stellar evolution effects are less severe than those observed at optical wavelenghts. Rapid evolution of the stars on the asymptotic giant branch is easily recognized in the simulated data for both cosmologies and serves to discriminate between the two extreme values of Omega(O). Measurements of total magnitudes of individual galaxies are not essential for studying light distribution in galaxies as a function of redshift. Calculations for the extragalactic background radiation are carried out using the simulated data, and compared to integrals over the evolutionary models used. 29 refs

A Wigner quasi-distribution function for charged particles in classical electromagnetic fields

International Nuclear Information System (INIS)

Levanda, M.; Fleurov, V.

2001-01-01

A gauge-invariant Wigner quasi-distribution function for charged particles in classical electromagnetic fields is derived in a rigorous way. Its relation to the axial gauge is discussed, as well as the relation between the kinetic and canonical momenta in the Wigner representation. Gauge-invariant quantum analogs of Hamilton-Jacobi and Boltzmann kinetic equations are formulated for arbitrary classical electromagnetic fields in terms of the 'slashed' derivatives and momenta, introduced for this purpose. The kinetic meaning of these slashed quantities is discussed. We introduce gauge-invariant conditional moments and use them to derive a kinetic momentum continuity equation. This equation provides us with a hydrodynamic representation for quantum transport processes and a definition of the 'collision force'. The hydrodynamic equation is applied for the rotation part of the electron motion. The theory is illustrated by its application in three examples: Wigner quasi-distribution function and equations for an electron in a magnetic field and harmonic potential; Wigner quasi-distribution function for a charged particle in periodic systems using the kq representation; two Wigner quasi-distribution functions for heavy-mass polaron in an electric field

Predictive local receptive fields based respiratory motion tracking for motion-adaptive radiotherapy.

Science.gov (United States)

Yubo Wang; Tatinati, Sivanagaraja; Liyu Huang; Kim Jeong Hong; Shafiq, Ghufran; Veluvolu, Kalyana C; Khong, Andy W H

2017-07-01

Extracranial robotic radiotherapy employs external markers and a correlation model to trace the tumor motion caused by the respiration. The real-time tracking of tumor motion however requires a prediction model to compensate the latencies induced by the software (image data acquisition and processing) and hardware (mechanical and kinematic) limitations of the treatment system. A new prediction algorithm based on local receptive fields extreme learning machines (pLRF-ELM) is proposed for respiratory motion prediction. All the existing respiratory motion prediction methods model the non-stationary respiratory motion traces directly to predict the future values. Unlike these existing methods, the pLRF-ELM performs prediction by modeling the higher-level features obtained by mapping the raw respiratory motion into the random feature space of ELM instead of directly modeling the raw respiratory motion. The developed method is evaluated using the dataset acquired from 31 patients for two horizons in-line with the latencies of treatment systems like CyberKnife. Results showed that pLRF-ELM is superior to that of existing prediction methods. Results further highlight that the abstracted higher-level features are suitable to approximate the nonlinear and non-stationary characteristics of respiratory motion for accurate prediction.

Some connections between relativistic classical mechanics, statistical mechanics, and quantum field theory

International Nuclear Information System (INIS)

Remler, E.A.

1977-01-01

A gauge-invariant version of the Wigner representation is used to relate relativistic mechanics, statistical mechanics, and quantum field theory in the context of the electrodynamics of scalar particles. A unified formulation of quantum field theory and statistical mechanics is developed which clarifies the physics interpretation of the single-particle Wigner function. A covariant form of Ehrenfest's theorem is derived. Classical electrodynamics is derived from quantum field theory after making a random-phase approximation. The validity of this approximation is discussed

Full-reference quality assessment of stereoscopic images by learning binocular receptive field properties.

Science.gov (United States)

Shao, Feng; Li, Kemeng; Lin, Weisi; Jiang, Gangyi; Yu, Mei; Dai, Qionghai

2015-10-01

Quality assessment of 3D images encounters more challenges than its 2D counterparts. Directly applying 2D image quality metrics is not the solution. In this paper, we propose a new full-reference quality assessment for stereoscopic images by learning binocular receptive field properties to be more in line with human visual perception. To be more specific, in the training phase, we learn a multiscale dictionary from the training database, so that the latent structure of images can be represented as a set of basis vectors. In the quality estimation phase, we compute sparse feature similarity index based on the estimated sparse coefficient vectors by considering their phase difference and amplitude difference, and compute global luminance similarity index by considering luminance changes. The final quality score is obtained by incorporating binocular combination based on sparse energy and sparse complexity. Experimental results on five public 3D image quality assessment databases demonstrate that in comparison with the most related existing methods, the devised algorithm achieves high consistency with subjective assessment.

Classical and macroquantum dynamics of charged particles in a magnetic field

International Nuclear Information System (INIS)

Varma, R.K.

2003-01-01

The investigations relating to the dynamics of charged particles in a magnetic field carried out over more than 40 years have been reviewed with special reference to the problem of nonadiabaticity due to field inhomogeneity, and time dependence. A detailed overview is presented of the standard approaches to one of the main problems namely the determination of the residence times of charged particles in an adiabatic magnetic trap which involves nonadiabaticity in a crucial way. In a major departure from the standard approach, a new paradigm described here as 'macroquantum dynamics' was advanced by the author to address the problem of residence times. The evolution and development of this new paradigm is next presented as the main focus of the review. This consists of a probability amplitude Schroedinger-like formalism for the classical macrodomain, which has been shown to be a description of the system in the correspondence limit of large Landau quantum numbers. It is demonstrated that this represents a remarkable persistence of matter wave behaviour well into the classical macrodomain, leading to unexpected experimental consequences. Experimental results confirming some of the spectacular predictions of this formalism are presented. These refer to the existence of macroscopic matter wave interference phenomena and the observation of the curl-free vector potential a la Aharonov-Bohm in the macrodomain. The problem of the nonadiabatic leakage of particles from an adiabatic trap takes the appearance here of the quantum-like tunneling of the adiabatic potential. The multiplicity of residence times predicted by the set of Schroedinger-like equations have been well confirmed by experiments. A critical comparison is finally presented of the classical vs. macroquantum description of the system in the macrodomain. The new paradigm thus represents an entirely new and unexpected manifestation of quantum dynamics in the classical macrodomain

Quantum classical correspondence in nonrelativistic electrodynamics

International Nuclear Information System (INIS)

Ritchie, B.; Weatherford, C.A.

1999-01-01

A form of classical electrodynamic field exists which gives exact agreement with the operator field of quantum electrodynamics (QED) for the Lamb shift of a harmonically bound point electron. Here it is pointed out that this form of classical theory, with its physically acceptable interpretation, is the result of an unconventional resolution of a mathematically ambiguous term in classical field theory. Finally, a quantum classical correspondence principle is shown to exist in the sense that the classical field and expectation value of the QED operator field are identical, if retardation is neglected in the latter

Restrictions on Possible Forms of Classical Matter Fields Carrying no Energy

International Nuclear Information System (INIS)

Sokolowski, L.M.

2004-01-01

It is postulated in general relativity that the matter energy-momentum tensor vanishes if and only if all the matter fields vanish. In classical Lagrangian field theory the energy and momentum density are described by the variational (symmetric) energy-momentum tensor (named the stress tensor) and a priori it might occur that for some systems the tensor is identically to zero for all field configurations whereas evolution of the system is subject to deterministic Lagrange equations of motion. Such a system would not generate its own gravitational field. To check if these systems can exist in the framework of classical field theory we find a relationship between the stress tensor and the Euler operator (i.e. the Lagrange field equations). We prove that if a system of interacting scalar fields (the number of fields cannot exceed the spacetime dimension d) or a single vector field (in spacetimes with d even) has the stress tensor such that its divergence is identically zero (i.e. ''on and of shell''), then the Lagrange equations of motion hold identically too. These systems have then no propagation equations at all and should be regarded as unphysical. Thus nontrivial field equations require the stress tensor be nontrivial too. This relationship between vanishing (of divergence) of the stress tensor and of the Euler operator breaks down if the number of fields is greater than d. We show on concrete examples that a system of n > d interacting scalars or two interacting vector fields can have the stress tensor equal identically to zero while their propagation equations are nontrivial. This means that non-self-gravitating (and yet detectable) field systems are in principle admissible. Their equations of motion are, however, in some sense degenerate. We also show, that for a system of arbitrary number of interacting scalar fields or for a single vector field (in some specific spacetimes in the latter case), if the stress tensor is not identically zero, then it cannot

A discrete classical space-time could require 6 extra-dimensions

Science.gov (United States)

Guillemant, Philippe; Medale, Marc; Abid, Cherifa

2018-01-01

We consider a discrete space-time in which conservation laws are computed in such a way that the density of information is kept bounded. We use a 2D billiard as a toy model to compute the uncertainty propagation in ball positions after every shock and the corresponding loss of phase information. Our main result is the computation of a critical time step above which billiard calculations are no longer deterministic, meaning that a multiverse of distinct billiard histories begins to appear, caused by the lack of information. Then, we highlight unexpected properties of this critical time step and the subsequent exponential evolution of the number of histories with time, to observe that after certain duration all billiard states could become possible final states, independent of initial conditions. We conclude that if our space-time is really a discrete one, one would need to introduce extra-dimensions in order to provide supplementary constraints that specify which history should be played.

Equation of Motion of a Mass Point in Gravitational Field and Classical Tests of Gauge Theory of Gravity

International Nuclear Information System (INIS)

Wu Ning; Zhang Dahua

2007-01-01

A systematic method is developed to study the classical motion of a mass point in gravitational gauge field. First, by using Mathematica, a spherical symmetric solution of the field equation of gravitational gauge field is obtained, which is just the traditional Schwarzschild solution. Combining the principle of gauge covariance and Newton's second law of motion, the equation of motion of a mass point in gravitational field is deduced. Based on the spherical symmetric solution of the field equation and the equation of motion of a mass point in gravitational field, we can discuss classical tests of gauge theory of gravity, including the deflection of light by the sun, the precession of the perihelia of the orbits of the inner planets and the time delay of radar echoes passing the sun. It is found that the theoretical predictions of these classical tests given by gauge theory of gravity are completely the same as those given by general relativity.

Relativistic and nonrelativistic classical field theory on fivedimensional space-time

International Nuclear Information System (INIS)

Kunzle, H.P.; Duval, C.

1985-07-01

This paper is a sequel to earlier ones in which, on the one hand, classical field theories were described on a curved Newtonian space-time, and on the other hand, the Newtonian gravitation theory was formulated on a fivedimensional space-time with a metric of signature and a covariantly constant vector field. Here we show that Lagrangians for matter fields are easily formulated on this extended space-time from simple invariance arguments and that stress-energy tensors can be derived from them in the usual manner so that four-dimensional space-time expressions are obtained that are consistent in the relativistic as well as in the Newtonian case. In the former the theory is equivalent to General Relativity. When the magnitude of the distinguished vector field vanishes equations for the (covariant) Newtonian limit follow. We demonstrate this here explicity in the case of the Klein-Gordon/Schroedinger and the Dirac field and its covariant nonrelativistic analogue, the Levy-Leblond field. Especially in the latter example the covariant Newtonian theory simplifies dramatically in this fivedimensional form

A New Semi-Symmetric Unified Field Theory of the Classical Fields of Gravity and Electromagnetism

Directory of Open Access Journals (Sweden)

Suhendro I.

2007-10-01

Full Text Available We attempt to present a classical theoretical framework in which the gravitational and electromagnetic fields are unified as intrinsic geometric objects in the space-time manifold. For this purpose, we first present the preliminary geometric considerations dealing with the metric differential geometry of Cartan connections. The unified field theory is then developed as an extension of the general theory of relativity based on a semi- symmetric Cartan connection which is meant to be as close as possible structurally to the symmetric connection of the Einstein-Riemann space-time.

Quantifying inbreeding avoidance through extra-pair reproduction.

Science.gov (United States)

Reid, Jane M; Arcese, Peter; Keller, Lukas F; Germain, Ryan R; Duthie, A Bradley; Losdat, Sylvain; Wolak, Matthew E; Nietlisbach, Pirmin

2015-01-01

Extra-pair reproduction is widely hypothesized to allow females to avoid inbreeding with related socially paired males. Consequently, numerous field studies have tested the key predictions that extra-pair offspring are less inbred than females' alternative within-pair offspring, and that the probability of extra-pair reproduction increases with a female's relatedness to her socially paired male. However, such studies rarely measure inbreeding or relatedness sufficiently precisely to detect subtle effects, or consider biases stemming from failure to observe inbred offspring that die during early development. Analyses of multigenerational song sparrow (Melospiza melodia) pedigree data showed that most females had opportunity to increase or decrease the coefficient of inbreeding of their offspring through extra-pair reproduction with neighboring males. In practice, observed extra-pair offspring had lower inbreeding coefficients than females' within-pair offspring on average, while the probability of extra-pair reproduction increased substantially with the coefficient of kinship between a female and her socially paired male. However, simulations showed that such effects could simply reflect bias stemming from inbreeding depression in early offspring survival. The null hypothesis that extra-pair reproduction is random with respect to kinship therefore cannot be definitively rejected in song sparrows, and existing general evidence that females avoid inbreeding through extra-pair reproduction requires reevaluation given such biases. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

On classical solutions of SU(3) gauge field equations

International Nuclear Information System (INIS)

Chakrabarti, A.

1975-01-01

Static classical solutions of SU(3) gauge field equations are studied. The roles of the O(3) subgroup and of the quadrupole generators are discussed systematically. The general form thus obtained leads, through-out, to a high degree of symmetry in the results. This brings in some simplifying features. An octet of scalar mesons is finally added. Certain classes of exact solutions are given that are singular at the origin. A generalized gauge condition is pointed out. The relation of the general form to known particular cases is discussed [fr

Magnetic properties of a classical XY spin dimer in a “planar” magnetic field

Energy Technology Data Exchange (ETDEWEB)

Ciftja, Orion, E-mail: ogciftja@pvamu.edu [Department of Physics, Prairie View A& M University, Prairie View, TX 77446 (United States); Prenga, Dode [Department of Physics, Faculty of Natural Sciences, University of Tirana, Bul. Zog I, Tirana (Albania)

2016-10-15

Single-molecule magnetism originates from the strong intra-molecular magnetic coupling of a small number of interacting spins. Such spins generally interact very weakly with the neighboring spins in the other molecules of the compound, therefore, inter-molecular spin couplings are negligible. In certain cases the number of magnetically coupled spins is as small as a dimer, a system that can be considered the smallest nanomagnet capable of storing non-trivial magnetic information on the molecular level. Additional interesting patterns arise if the spin motion is confined to a two-dimensional space. In such a scenario, clusters consisting of spins with large-spin values are particularly attractive since their magnetic interactions can be described well in terms of classical Heisenberg XY spins. In this work we calculate exactly the magnetic properties of a nanomagnetic dimer of classical XY spins in a “planar” external magnetic field. The problem is solved by employing a mathematical approach whose idea is the introduction of auxiliary spin variables into the starting expression of the partition function. Results for the total internal energy, total magnetic moment, spin–spin correlation function and zero-field magnetic susceptibility can serve as a basis to understand the magnetic properties of large-spin dimer building blocks. - Highlights: • Exact magnetic properties of a dimer system of classical XY spins in magnetic field. • Partition function in nonzero magnetic field obtained in closed-form. • Novel exact analytic results are important for spin models in a magnetic field. • Result provides benchmarks to gauge the accuracy of computational techniques.

Classical descriptions of the electron trajectories in the He atom

International Nuclear Information System (INIS)

Miko, A.; Toekesi, K.

2006-01-01

Complete text of publication follows. The classical-trajectory Monte Carlo method (CTMC) treats the atomic systems as small solar-systems, where the electrons are moving around the nucleus in properly chosen Kepler-orbits. It is also well known that the multi-electron classical atomic systems are instable due to the autoionization through electron-electron interactions. Therefore most of the classical descriptions use the so called independent particle approach, i.e. they neclect the electron-electron interactions. In the quasiclassical trajectory Monte Carlo method (QCTMC) appears a qualitative improvement of the classical description of the multi-electron atoms namely the electron-electron interaction is entirely taken into account by the help of the extra potentials providing the validations of the Pauli exclusion principle and the Heisenberg uncertainty principle. The extra potentials ensure that the multi electron atoms are stable even if all electron-electron interactions are taken into account. The extra potentials - representing the constrains - can be written in the following form [1] V τ -2 f(τp; ξ); where f is the monotonic decreasing function of the relative distance τ and momentum p and ξ is the constant characterized the given atomic state. Figure 1. shows the typical electron trajectories in the helium atom. The calculations were carried out using CTMC model when the electron-electron interaction is neglected (Fig. 1a). In this case the He atom is stable and the electron orbits are closed. However, when the electron-electron interaction is taken into account in the CTMC model the electron trajectories in the He atom show chaotic behavior and after a few cycles autoionization occurs (Fig. 1b). In the QCTMC model the electron trajectories are also closed and stable (Fig. 1c). (author)

Multi-reception strategy with improved SNR for multichannel MR imaging.

Directory of Open Access Journals (Sweden)

Bing Wu

Full Text Available A multi-reception strategy with extended GRAPPA is proposed in this work to improve MR imaging performance at ultra-high field MR systems with limited receiver channels. In this method, coil elements are separated to two or more groups under appropriate grouping criteria. Those groups are enabled in sequence for imaging first, and then parallel acquisition is performed to compensate for the redundant scan time caused by the multiple receptions. To efficiently reconstruct the data acquired from elements of each group, a specific extended GRAPPA was developed. This approach was evaluated by using a 16-element head array on a 7 Tesla whole-body MRI scanner with 8 receive channels. The in-vivo experiments demonstrate that with the same scan time, the 16-element array with twice receptions and acceleration rate of 2 can achieve significant SNR gain in the periphery area of the brain and keep nearly the same SNR in the center area over an eight-element array, which indicates the proposed multi-reception strategy and extended GRAPPA are feasible to improve image quality for MRI systems with limited receive channels. This study also suggests that it is advantageous for a MR system with N receiver channels to utilize a coil array with more than N elements if an appropriate acquisition strategy is applied.

A novel graphene nanoribbon FET with an extra peak electric field (EFP-GNRFET) for enhancing the electrical performances

Energy Technology Data Exchange (ETDEWEB)

Akbari Eshkalak, Maedeh [Young Researchers and Elite Club, Lahijan Branch, Islamic Azad University, Lahijan (Iran, Islamic Republic of); Anvarifard, Mohammad K., E-mail: m.anvarifard@guilan.ac.ir [Department of Engineering Sciences, Faculty of Technology and Engineering, East of Guilan, University of Guilan, Rudsar-Vajargah (Iran, Islamic Republic of)

2017-04-25

This work has provided an efficient technique to improve the electrical performance for the Graphene Nanoribbon Field Effect Transistors (GNRFETs) successfully. The physical gate length is divided into two gates named as the original gate and the other one as the virtual gate. We have applied a voltage source between these gates to control the channel of the GNRFETs. This technique has created an extra peak electric field in the middle of the channel resulting in the redistribution of surface potential profile. The proposed structure named as EFP-GNRFET has been compared with a simple GNRFET and has shown many improvements in terms of the critical parameters such as short channel effects, leakage current, subthreshold swing, ON-state to OFF-state current ratio, transconductance, output conductance and voltage gain. The structures under the study in this paper benefits from the Non-Equilibrium Green Function (NEGF) approach for solving Schrödinger equation coupled with the two-dimensional (2D) Poisson equation in a self-consistent manner. - Highlights: • Proposal of a novel graphene nanoribbon FET. • Creation of an extra peak in electric field. • Modification of the channel potential with the help of virtual gate. • Considerable improvement on electrical performances.

Geometrical phases from global gauge invariance of nonlinear classical field theories

International Nuclear Information System (INIS)

Garrison, J.C.; Chiao, R.Y.

1988-01-01

We show that the geometrical phases recently discovered in quantum mechanics also occur naturally in the theory of any classical complex multicomponent field satisfying nonlinear equations derived from a Lagrangean with is invariant under gauge transformations of the first kind. Some examples are the paraxial wave equation for nonlinear optics, and Ginzburg-Landau equations for complex order parameters in condensed-matter physics

Statistical metastability of a classical ideal gas in the Schwarzschild gravitational field

International Nuclear Information System (INIS)

Gaina, A.B.; Zaslavskii, O.B.

1990-01-01

A classical ideal gas in the Schwarzschild gravitational field is considered. The lifetime of a gas influenced by thermal fluctuations has been calculated. It is shown that thermal effects can lead to the electric charging of a black hole in a plasma containing particles with different masses. (author)

Dirac particle in a plane wave field and the semi-classical approximation

Energy Technology Data Exchange (ETDEWEB)

Bourouaine, S. [Department of Physics, Faculty of Sciences, Mentouri University, Constantine (Algeria)

2005-04-01

In this paper we investigate the influence of photon represented by plane wave field on Dirac particle in the context of path integral approach given by Fradkin and Gitman formalism. In our case, although the action relative to Dirac particle in plane wave field seems to be non quadratic, the result obtained by semi-classical approach is the same as that found by an exact calculation. Hence; when we add the plane wave field to any quadratic actions related to Fradkin and Gitman approach, the total action behaves like quadratic. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

Dirac particle in a plane wave field and the semi-classical approximation

International Nuclear Information System (INIS)

Bourouaine, S.

2005-01-01

In this paper we investigate the influence of photon represented by plane wave field on Dirac particle in the context of path integral approach given by Fradkin and Gitman formalism. In our case, although the action relative to Dirac particle in plane wave field seems to be non quadratic, the result obtained by semi-classical approach is the same as that found by an exact calculation. Hence; when we add the plane wave field to any quadratic actions related to Fradkin and Gitman approach, the total action behaves like quadratic. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

Learning Receptive Fields and Quality Lookups for Blind Quality Assessment of Stereoscopic Images.

Science.gov (United States)

Shao, Feng; Lin, Weisi; Wang, Shanshan; Jiang, Gangyi; Yu, Mei; Dai, Qionghai

2016-03-01

Blind quality assessment of 3D images encounters more new challenges than its 2D counterparts. In this paper, we propose a blind quality assessment for stereoscopic images by learning the characteristics of receptive fields (RFs) from perspective of dictionary learning, and constructing quality lookups to replace human opinion scores without performance loss. The important feature of the proposed method is that we do not need a large set of samples of distorted stereoscopic images and the corresponding human opinion scores to learn a regression model. To be more specific, in the training phase, we learn local RFs (LRFs) and global RFs (GRFs) from the reference and distorted stereoscopic images, respectively, and construct their corresponding local quality lookups (LQLs) and global quality lookups (GQLs). In the testing phase, blind quality pooling can be easily achieved by searching optimal GRF and LRF indexes from the learnt LQLs and GQLs, and the quality score is obtained by combining the LRF and GRF indexes together. Experimental results on three publicly 3D image quality assessment databases demonstrate that in comparison with the existing methods, the devised algorithm achieves high consistent alignment with subjective assessment.

EXTraS: Exploring the X-ray Transient and variable Sky

Science.gov (United States)

De Luca, A.; Salvaterra, R.; Tiengo, A.; D'Agostino, D.; Watson, M.; Haberl, F.; Wilms, J.

2017-10-01

The EXTraS project extracted all temporal domain information buried in the whole database collected by the EPIC cameras onboard the XMM-Newton mission. This included a search and characterisation of variability, both periodic and aperiodic, in hundreds of thousands of sources spanning more than eight orders of magnitude in time scale and six orders of magnitude in flux, as well as a search for fast transients, missed by standard image analysis. Phenomenological classification of variable sources, based on X-ray and multiwavelength information, has also been performed. All results and products of EXTraS are made available to the scientific community through a web public data archive. A dedicated science gateway will allow scientists to apply EXTraS pipelines on new observations. EXTraS is the most comprehensive analysis of variability, on the largest ever sample of soft X-ray sources. The resulting archive and tools disclose an enormous scientific discovery space to the community, with applications ranging from the search for rare events to population studies, with impact on the study of virtually all astrophysical source classes. EXTraS, funded within the EU/FP7 framework, is carried out by a collaboration including INAF (Italy), IUSS (Italy), CNR/IMATI (Italy), University of Leicester (UK), MPE (Germany) and ECAP (Germany).

Inflation from extra dimensions

International Nuclear Information System (INIS)

Barr, S.M.

1984-01-01

Recently there has been growing interest (1) in the possibility that the universe could have more than four dimensions. Aside from any light this may shed on problems in particle physics, if true it would undoubtedly have important implications for early cosmology. A rather speculative but very appealing possibility suggested by D. Sahdev and by E. Alvarez and B. Gavela is that the gravitational collapse of extra spatial dimensions could drive an inflation of ordinary space. This kind of inflationary cosmology would be quite different from the inflationary cosmologies now so intensively studied which are supposed to result from changes in vacuum energy during phase transitions in the early universe. In our work we examine the physics of these Kaluza-Klein inflationary cosmologies and come to three main conclusions. (1) It is desirable to have many extra dimensions, many being of order forty or fifty. (2) For models which give a realistically large inflation almost all of this inflation occurs in a period when quantum gravity is certainly important. This means that Einstein's equations cannot be used to calculate the details of this inflationary period. (3) Under plausible assumptions one may argue from the second law of thermodynamics that given appropriate initial conditions a large inflation will occur even when details of the inflationary phase cannot be calculated classically

TEACHING COMMUNICATIVE TRANSLATION: AN ACTIVE RECEPTION ANALYSIS BETWEEN THE TRANSLATION AND READER’S RECEPTION

Directory of Open Access Journals (Sweden)

Venny Eka Meidasari

2014-06-01

Full Text Available Literary theory sees reception theory from the reader response that emphasizes the reader’s reception of a literary text. It is generally called audience reception in the analysis of communications models. In literary studies, reception theory originated from the work of Hans-Robert Jauss in the late 1960s. Communication only means that the original message will be clearly sent in its equivalent context to the target receptor. Similarly, the main role of translators is to send the message across without any form of distortion or emphasis. It is delivering the genuine context of the message to the language that the active receptor understands. A single mistake in a context translation can result to offensive message that can eventually lead to misunderstandings between active receptors. This paper proposes on the role of translator as the mediator between a writer of the original text and the active target language receptors of translated version in the course of communication which definitely affects the process and result of translation practice. It also reveals the emphasis on the creation text of the translation theories originated from the strategic communication theories, which hopefully leads to a dream of the most equivalence between the text and the translated version.

On the existence of classical solutions for stationary extended mean field games

KAUST Repository

Gomes, Diogo A.; Patrizi, Stefania; Voskanyan, Vardan

2014-01-01

In this paper we consider extended stationary mean-field games, that is mean-field games which depend on the velocity field of the players. We prove various a-priori estimates which generalize the results for quasi-variational mean-field games in Gomes et al. (2012). In addition we use adjoint method techniques to obtain higher regularity bounds. Then we establish the existence of smooth solutions under fairly general conditions by applying the continuity method. When applied to standard stationary mean-field games as in Lasry and Lions (2006), Gomes and Sanchez-Morgado (2011) or Gomes et al. (2012) this paper yields various new estimates and regularity properties not available previously. We discuss additionally several examples where the existence of classical solutions can be proved. © 2013 Elsevier Ltd. All rights reserved.

On the existence of classical solutions for stationary extended mean field games

KAUST Repository

Gomes, Diogo A.

2014-04-01

In this paper we consider extended stationary mean-field games, that is mean-field games which depend on the velocity field of the players. We prove various a-priori estimates which generalize the results for quasi-variational mean-field games in Gomes et al. (2012). In addition we use adjoint method techniques to obtain higher regularity bounds. Then we establish the existence of smooth solutions under fairly general conditions by applying the continuity method. When applied to standard stationary mean-field games as in Lasry and Lions (2006), Gomes and Sanchez-Morgado (2011) or Gomes et al. (2012) this paper yields various new estimates and regularity properties not available previously. We discuss additionally several examples where the existence of classical solutions can be proved. © 2013 Elsevier Ltd. All rights reserved.

Phase-space representation of non-classical behaviour of scalar wave-fields

International Nuclear Information System (INIS)

Canas-Cardona, Gustavo; Castaneda, Roman; Vinck-Posada, Herbert

2011-01-01

The modelling of optical fields by using radiant and virtual point sources for the spatial coherence wavelets in the phase-space representation evidences some effects, conventionally attributed to non-classical correlations of light, although such type of correlations are not explicitly included in the model. Specifically, a light state is produced that has similar morphology to the Wigner Distribution Function of the well-known quantum Schroedinger cat and squeezed states.

Note from the Goods Reception services

CERN Multimedia

FI Department

2008-01-01

Members of the personnel are invited to take note that only parcels corresponding to official orders or contracts will be handled at CERN. Individuals are not authorised to have private merchandise delivered to them at CERN and private deliveries will not be accepted by the Goods Reception services. Goods Reception Services

Visual cortex in aging and Alzheimer’s disease: Changes in visual field maps and population receptive fields

Directory of Open Access Journals (Sweden)

Alyssa A. Brewer

2014-02-01

Full Text Available Although several studies have suggested that cortical alterations underlie such age-related visual deficits as decreased acuity, little is known about what changes actually occur in visual cortex during healthy aging. Two recent studies showed changes in primary visual cortex (V1 during normal aging; however, no studies have characterized the effects of aging on visual cortex beyond V1, important measurements both for understanding the aging process and for comparison to changes in age-related diseases. Similarly, there is almost no information about changes in visual cortex in Alzheimer’s disease (AD, the most common form of dementia. Because visual deficits are often reported as one of the first symptoms of AD, measurements of such changes in the visual cortex of AD patients might improve our understanding of how the visual system is affected by neurodegeneration as well as aid early detection, accurate diagnosis and timely treatment of AD. Here we use fMRI to first compare the visual field map (VFM organization and population receptive fields (pRFs between young adults and healthy aging subjects for occipital VFMs V1, V2, V3, and hV4. Healthy aging subjects do not show major VFM organizational deficits, but do have reduced surface area and increased pRF sizes in the foveal representations of V1, V2, and hV4 relative to healthy young control subjects. These measurements are consistent with behavioral deficits seen in healthy aging. We then demonstrate the feasibility and first characterization of these measurements in two patients with mild AD, which reveal potential changes in visual cortex as part of the pathophysiology of AD. Our data aid in our understanding of the changes in the visual processing pathways in normal aging and provide the foundation for future research into earlier and more definitive detection of AD.

Rehabilitering og 'motion på recept'

DEFF Research Database (Denmark)

Larsen, Niels Sandholm; Larsen, Kristian

2008-01-01

af disse forskningsarbejder er etablering af fænomenet 'motion på recept'. Konceptet om 'motion på recept' stammer oprindelig fra Sverige, hvor praktiserende læger i en periode har haft mulighed for at henvise visse typer af patienter til fysisk træning hos praktiserende fysioterapeuter. Ribe Amt...... 2007)....

Comparison of visual receptive fields in the dorsolateral prefrontal cortex and ventral intraparietal area in macaques.

Science.gov (United States)

Viswanathan, Pooja; Nieder, Andreas

2017-12-01

The concept of receptive field (RF) describes the responsiveness of neurons to sensory space. Neurons in the primate association cortices have long been known to be spatially selective but a detailed characterisation and direct comparison of RFs between frontal and parietal association cortices are missing. We sampled the RFs of a large number of neurons from two interconnected areas of the frontal and parietal lobes, the dorsolateral prefrontal cortex (dlPFC) and ventral intraparietal area (VIP), of rhesus monkeys by systematically presenting a moving bar during passive fixation. We found that more than half of neurons in both areas showed spatial selectivity. Single neurons in both areas could be assigned to five classes according to the spatial response patterns: few non-uniform RFs with multiple discrete response maxima could be dissociated from the vast majority of uniform RFs showing a single maximum; the latter were further classified into full-field and confined foveal, contralateral and ipsilateral RFs. Neurons in dlPFC showed a preference for the contralateral visual space and collectively encoded the contralateral visual hemi-field. In contrast, VIP neurons preferred central locations, predominantly covering the foveal visual space. Putative pyramidal cells with broad-spiking waveforms in PFC had smaller RFs than putative interneurons showing narrow-spiking waveforms, but distributed similarly across the visual field. In VIP, however, both putative pyramidal cells and interneurons had similar RFs at similar eccentricities. We provide a first, thorough characterisation of visual RFs in two reciprocally connected areas of a fronto-parietal cortical network. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

The immigrants’ reception system in Italy. Reflections emerging from an experience of reception upon landing

OpenAIRE

Concetta Chiara Cannella; Gandolfa Cascio; Francesca Molonia; Serena Vitulo

2014-01-01

After the description of the main migration routes toward Italian territory, the article provides an overview of the laws and administrative policy instruments that characterize the system of reception and detention of migrants in Italy. This type of information can help psychosocial workers supporting migrants to better cope with various psychosocial issues, such as the landing in a foreign country. Following a report on the first reception intervention carried out in Palermo, Sicily, by Psi...

Language, gay pornography, and audience reception.

Science.gov (United States)

Leap, William L

2011-01-01

Erotic imagery is an important component of gay pornographic cinema, particularly, where work of audience reception is concerned. However, to assume the audience engagement with the films is limited solely to the erotic realm is to underestimate the workings of ideological power in the context and aftermath of reception. For example, the director of the film under discussion here (Men of Israel; Lucas, 2009b) intended to present an erotic celebration of the nation-state. Yet, most viewers ignore the particulars of context in their comments about audience reception, placing the "Israeli" narrative within a broader framework, using transnational rather than film-specific criteria to guide their "reading" of the Israeli-centered narrative. This article uses as its entry point the language that viewers employ when describing their reactions to Men of Israel on a gay video club's Web site; this article shows how the work of audience reception may draw attention to a film's erotic details while invoking social and political messages that completely reframe the film's erotic narrative.

Field transformations and the classical equation of motion in chiral perturbation theory

International Nuclear Information System (INIS)

Scherer, S.; Fearing, H.W.

1995-01-01

The construction of effective Lagrangians commonly involves the application of the ''classical equation of motion'' to eliminate redundant structures and thus generate the minimal number of independent terms. We investigate this procedure in the framework of chiral perturbation theory with particular emphasis on the new features which appear at O(p 6 ). The use of the ''classical equation of motion'' is interpreted in terms of field transformations. Such an interpretation is crucial if one wants to bring a given Lagrangian into a canonical form with a minimal number of terms. We emphasize that the application of field transformations leads to a modification of the coefficients of higher-order terms as well as eliminating structures, or what is equivalent, expressing certain structures in terms of already known different structures. This will become relevant once one considers the problem of expressing in canonical form a model effective interaction containing terms beyond next-to-leading order, i.e., beyond O(p 4 ). In such circumstances the naive application of the clasical equation of motion to simply drop terms, as is commonly done at lowest order, leads to subtle errors, which we discuss

Unaccompanied adolescents seeking asylum - Poorer mental health under a restrictive reception : poorer mental health under a restrictive reception

NARCIS (Netherlands)

Reijneveld, S.A.; de Boer, J.B.; Bean, T.; Korfker, D.G.

2005-01-01

We assessed the effects of a stringent reception policy on the mental health of unaccompanied adolescent asylum seekers by comparing the mental health of adolescents in a restricted campus reception setting and in a setting offering more autonomy (numbers [response rates]: 69 [93%] and 53 [69%],

Vacuum polarization and classical self-action near higher-dimensional defects

Energy Technology Data Exchange (ETDEWEB)

Grats, Yuri V.; Spirin, Pavel [Moscow State University, Department of Theoretical Physics, Faculty of Physics, Moscow (Russian Federation)

2017-02-15

We analyze the gravity-induced effects associated with a massless scalar field in a higher-dimensional spacetime being the tensor product of (d - n)-dimensional Minkowski space and n-dimensional spherically/cylindrically symmetric space with a solid/planar angle deficit. These spacetimes are considered as simple models for a multidimensional global monopole (if n ≥ 3) or cosmic string (if n = 2) with (d - n - 1) flat extra dimensions. Thus, we refer to them as conical backgrounds. In terms of the angular-deficit value, we derive the perturbative expression for the scalar Green function, valid for any d ≥ 3 and 2 ≤ n ≤ d - 1, and compute it to the leading order. With the use of this Green function we compute the renormalized vacuum expectation value of the field square left angle φ{sup 2}(x) right angle {sub ren} and the renormalized vacuum averaged of the scalar-field energy-momentum tensor left angle T{sub MN}(x) right angle {sub ren} for arbitrary d and n from the interval mentioned above and arbitrary coupling constant to the curvature ξ. In particular, we revisit the computation of the vacuum polarization effects for a non-minimally coupled massless scalar field in the spacetime of a straight cosmic string. The same Green function enables to consider the old purely classical problem of the gravity-induced self-action of a classical point-like scalar or electric charge, placed at rest at some fixed point of the space under consideration. To deal with divergences, which appear in consideration of the two problems, we apply the dimensional-regularization technique, widely used in quantum field theory. The explicit dependence of the results upon the dimensionalities of both the bulk and conical submanifold is discussed. (orig.)

Classical field theory on electrodynamics, non-abelian gauge theories and gravitation

CERN Document Server

Scheck, Florian

2018-01-01

Scheck’s successful textbook presents a comprehensive treatment, ideally suited for a one-semester course. The textbook describes Maxwell's equations first in their integral, directly testable form, then moves on to their local formulation. The first two chapters cover all essential properties of Maxwell's equations, including their symmetries and their covariance in a modern notation. Chapter 3 is devoted to Maxwell's theory as a classical field theory and to solutions of the wave equation. Chapter 4 deals with important applications of Maxwell's theory. It includes topical subjects such as metamaterials with negative refraction index and solutions of Helmholtz' equation in paraxial approximation relevant for the description of laser beams. Chapter 5 describes non-Abelian gauge theories from a classical, geometric point of view, in analogy to Maxwell's theory as a prototype, and culminates in an application to the U(2) theory relevant for electroweak interactions. The last chapter 6 gives a concise summary...

Production of partons in the presence of classical fields in ultrarelativistic heavy-ion collisions

International Nuclear Information System (INIS)

Dietrich, D.D.

2003-09-01

In this work the production of quarks, antiquarks and of gluonic fluctuations is studied in the presence of classical bosonic field. A comparison of the production of anti-quark pairs with the creation of pairs of gluonic quantum fluctuations based on perturbative calculations will be presented here. This analysis is valid for quantum particles with a large momentum compared to the magnitude of the classical vector potential multiplied by the coupling constant. The model contains 3 parameters: the initial magnitude of the gauge field, the coupling constant and the time scale on which the field decays. It appears that none of the species (quark-antiquark pairs, gluonic fluctuation pairs, bosons and fermion-anti fermions) can be neglected from the beginning. A corresponding calculation requires a non-perturbative description of at least the soft fermions. In this thesis the exact expression for fields varying arbitrarily in time is derived. After the full solution has been obtained, various approximation schemes are proposed for different domains, in order to find out into which the situation under consideration falls. There are approximations in the ultraviolet (perturbative), the infrared, and the Abelian (commutative) regime. The exact expression and the lowest orders of the different approximation schemes are evaluated in the presence of the model field with the same parameters as before. (A.C.)

Far-field detection of sub-wavelength Tetris without extra near-field metal parts based on phase prints of time-reversed fields with intensive background interference.

Science.gov (United States)

Chen, Yingming; Wang, Bing-Zhong

2014-07-14

Time-reversal (TR) phase prints are first used in far-field (FF) detection of sub-wavelength (SW) deformable scatterers without any extra metal structure positioned in the vicinity of the target. The 2D prints derive from discrete short-time Fourier transform of 1D TR electromagnetic (EM) signals. Because the time-invariant intensive background interference is effectively centralized by TR technique, the time-variant weak indication from FF SW scatterers can be highlighted. This method shows a different use of TR technique in which the focus peak of TR EM waves is unusually removed and the most useful information is conveyed by the other part.

Corrections to classical kinetic and transport theory for a two-temparature, fully ionized plasma in electromagnetic fields

International Nuclear Information System (INIS)

Oeien, A.H.

1977-06-01

Sets of lower order and higher order kinetic and macroscopic equations are developed for a plasma where collisions are important but electrons and ions are allowed to have different temperatures when transports, due to gradients and fields, set in. Solving the lower order kinetic equations and taking appropriate velocity moments we show that usual classical transports emerge. From the higher order kinetic equations special notice is taken of some new correction terms to the classical transports. These corrections are linear in gradients and fields, some of which are found in a two-temperature state only. (Auth.)

On the mathematical theory of classical fields and general relativity

CERN Document Server

Klainerman, S

1993-01-01

From the perspective of an analyst, like myself, the General Theory of Relativity provides an extrordinary rich and vastly virgin territory. It is the aim of my lecture to provide, first, an account of those aspects of the theory which attract me most and second a perspective of what has been accomplished so far in that respect. In trying to state our main objectives it helps to view General Relativity in the broader context of Classical Field Theory. EinsteiniVacuum equations, or shortly E—V, is already sufficiently complicated. I will thus restrict my attention to them.

Reception theory and the Christian reader: A preliminary perspective

Directory of Open Access Journals (Sweden)

A. L. Comhrink

1983-03-01

Full Text Available In recent years there has been a significant shift in emphasis from text- centred criticism in literature to reader-centred criticism. This new field of criticism, called Reception Theory or Reader Response Criticism, denies the immutable nature of the "text” and regards as its object of study the work of literature that is created through the co-constituent creative and interpre­tive acts o f both writer and reader.

Diversity Networking Reception

Science.gov (United States)

2014-03-01

Join us at the APS Diversity Reception to relax, network with colleagues, and learn about programs and initiatives for women, underrepresented minorities, and LGBT physicists. You'll have a great time meeting friends in a supportive environment and making connections.

Radiation reaction for the classical relativistic spinning particle in scalar, tensor and linearized gravitational fields

International Nuclear Information System (INIS)

Barut, A.O.; Cruz, M.G.

1992-08-01

We use the method of analytic continuation of the equation of motion including the self-fields to evaluate the radiation reaction for a classical relativistic spinning point particle in interaction with scalar, tensor and linearized gravitational fields in flat spacetime. In the limit these equations reduce to those of spinless particles. We also show the renormalizability of these theories. (author). 10 refs

Hierarchies without symmetries from extra dimensions

International Nuclear Information System (INIS)

Arkani-Hamed, Nima; Schmaltz, Martin

2000-01-01

It is commonly thought that small couplings in a low-energy theory, such as those needed for the fermion mass hierarchy or proton stability, must originate from symmetries in a high-energy theory. We show that this expectation is violated in theories where the standard model fields are confined to a thick wall in extra dimensions, with the fermions ''stuck'' at different points in the wall. Couplings between them are then suppressed due to the exponentially small overlaps of their wave functions. This provides a framework for understanding both the fermion mass hierarchy and proton stability without imposing symmetries, but rather in terms of higher dimensional geography. A model independent prediction of this scenario is non-universal couplings of the standard model fermions to the ''Kaluza-Klein'' excitations of the gauge fields. This allows a measurement of the fermion locations in the extra dimensions at the CERN LHC or NLC if the wall thickness is close to the TeV scale. (c) 2000 The American Physical Society

Hierarchies Without Symmetries from Extra Dimensions

International Nuclear Information System (INIS)

Arkani-Hamed, Nima

1999-01-01

It is commonly thought that small couplings in a low-energy theory, such as those needed for the fermion mass hierarchy or proton stability, must originate from symmetries in a high-energy theory. We show that this expectation is violated in theories where the Standard Model fields are confined to a thick wall in extra dimensions, with the fermions ''stuck'' at different points in the wall. Couplings between them are then suppressed due to the exponentially small overlaps of their wave functions. This provides a framework for understanding both the fermion mass hierarchy and proton stability without imposing symmetries, but rather in terms of higher dimensional geography. A model independent prediction of this scenario is non-universal couplings of the Standard Model fermions to the ''Kaluza-Klein'' excitations of the gauge fields. This allows a measurement of the fermion locations in the extra dimensions at the LHC or NLC if the wall thickness is close to the TeV scale

Improved tests of extra-dimensional physics and thermal quantum field theory from new Casimir force measurements

International Nuclear Information System (INIS)

Decca, R.S.; Fischbach, E.; Klimchitskaya, G.L.; Mostepanenko, V.M.; Krause, D.E.; Lopez, D.

2003-01-01

We report new constraints on extra-dimensional models and other physics beyond the standard model based on measurements of the Casimir force between two dissimilar metals for separations in the range 0.2-1.2 μm. The Casimir force between a Au-coated sphere and a Cu-coated plate of a microelectromechanical torsional oscillator was measured statically with an absolute error of 0.3 pN. In addition, the Casimir pressure between two parallel plates was determined dynamically with an absolute error of ≅0.6 mPa. Within the limits of experimental and theoretical errors, the results are in agreement with a theory that takes into account the finite conductivity and roughness of the two metals. The level of agreement between experiment and theory was then used to set limits on the predictions of extra-dimensional physics and thermal quantum field theory. It is shown that two theoretical approaches to the thermal Casimir force which predict effects linear in temperature are ruled out by these experiments. Finally, constraints on Yukawa corrections to Newton's law of gravity are strengthened by more than an order of magnitude in the range 56-330 nm

Receptivity to Tobacco Advertising and Susceptibility to Tobacco Products.

Science.gov (United States)

Pierce, John P; Sargent, James D; White, Martha M; Borek, Nicolette; Portnoy, David B; Green, Victoria R; Kaufman, Annette R; Stanton, Cassandra A; Bansal-Travers, Maansi; Strong, David R; Pearson, Jennifer L; Coleman, Blair N; Leas, Eric; Noble, Madison L; Trinidad, Dennis R; Moran, Meghan B; Carusi, Charles; Hyland, Andrew; Messer, Karen

2017-06-01

Non-cigarette tobacco marketing is less regulated and may promote cigarette smoking among adolescents. We quantified receptivity to advertising for multiple tobacco products and hypothesized associations with susceptibility to cigarette smoking. Wave 1 of the nationally representative PATH (Population Assessment of Tobacco and Health) study interviewed 10 751 adolescents who had never used tobacco. A stratified random selection of 5 advertisements for each of cigarettes, e-cigarettes, smokeless products, and cigars were shown from 959 recent tobacco advertisements. Aided recall was classified as low receptivity, and image-liking or favorite ad as higher receptivity. The main dependent variable was susceptibility to cigarette smoking. Among US youth, 41% of 12 to 13 year olds and half of older adolescents were receptive to at least 1 tobacco advertisement. Across each age group, receptivity to advertising was highest for e-cigarettes (28%-33%) followed by cigarettes (22%-25%), smokeless tobacco (15%-21%), and cigars (8%-13%). E-cigarette ads shown on television had the highest recall. Among cigarette-susceptible adolescents, receptivity to e-cigarette advertising (39.7%; 95% confidence interval [CI]: 37.9%-41.6%) was higher than for cigarette advertising (31.7%; 95% CI: 29.9%-33.6%). Receptivity to advertising for each tobacco product was associated with increased susceptibility to cigarette smoking, with no significant difference across products (similar odds for both cigarette and e-cigarette advertising; adjusted odds ratio = 1.22; 95% CI: 1.09-1.37). A large proportion of US adolescent never tobacco users are receptive to tobacco advertising, with television advertising for e-cigarettes having the highest recall. Receptivity to advertising for each non-cigarette tobacco product was associated with susceptibility to smoke cigarettes. Copyright © 2017 by the American Academy of Pediatrics.

Classical geometrical interpretation of ghost fields and anomalies in Yang-Mills theory and quantum gravity

International Nuclear Information System (INIS)

Thierry-Mieg, J.

1985-01-01

The reinterpretation of the BRS equations of Quantum Field Theory as the Maurer Cartan equation of a classical principal fiber bundle leads to a simple gauge invariant classification of the anomalies in Yang Mills theory and gravity

Searches for dark matter and extra dimensions with the ATLAS detector

CERN Document Server

Mueller, T; The ATLAS collaboration

2014-01-01

Different approaches to finding evidence for dark matter at the LHC are presented. These include searches for events with large missing transverse momentum and a single jet, photon or W/Z boson, as well as events with long-lived particles resulting in displaced hadronic vertices or lepton-jet signatures. Those studies are also sensitive to the presence of extra spatial dimensions. Additional searches for classical and quantum black holes are also described.

Searches for dark matter and extra dimensions with the ATLAS detector

Directory of Open Access Journals (Sweden)

Kruskal Michael

2015-01-01

Full Text Available Different approaches to finding evidence for dark matter at the LHC are presented. These include searches for events with large missing transverse momentum and a single jet, photon or W/Z boson. Studies sensitive to the presence of extra spatial dimensions are also described, such as classical or quantum black holes and other non-resonant phenomena. Results are presented from the √s=8 TeV data taking period.

Effective Field Theories and Matching for Codimension-2 Branes

CERN Document Server

Burgess, C P; De Rham, C; Tasinato, G

2009-01-01

It is generic for the bulk fields sourced by branes having codimension two and higher to diverge at the brane position, much as does the Coulomb potential at the position of its source charge. This complicates finding the relation between brane properties and the bulk geometries they source. (These complications do not arise for codimension-1 sources, such as in RS geometries, because of the special properties unique to codimension one.) Understanding these relations is a prerequisite for phenomenological applications involving higher-codimension branes. Using codimension-2 branes in extra-dimensional scalar-tensor theories as an example, we identify the classical matching conditions that relate the near-brane asymptotic behaviour of bulk fields to the low-energy effective actions describing how space-filling codimension-2 branes interact with the surrounding extra-dimensional bulk. We do so by carefully regulating the near-brane divergences, and show how these may be renormalized in a general way. Among the ...

Noether symmetries, energy-momentum tensors, and conformal invariance in classical field theory

International Nuclear Information System (INIS)

Pons, Josep M.

2011-01-01

In the framework of classical field theory, we first review the Noether theory of symmetries, with simple rederivations of its essential results, with special emphasis given to the Noether identities for gauge theories. With this baggage on board, we next discuss in detail, for Poincare invariant theories in flat spacetime, the differences between the Belinfante energy-momentum tensor and a family of Hilbert energy-momentum tensors. All these tensors coincide on shell but they split their duties in the following sense: Belinfante's tensor is the one to use in order to obtain the generators of Poincare symmetries and it is a basic ingredient of the generators of other eventual spacetime symmetries which may happen to exist. Instead, Hilbert tensors are the means to test whether a theory contains other spacetime symmetries beyond Poincare. We discuss at length the case of scale and conformal symmetry, of which we give some examples. We show, for Poincare invariant Lagrangians, that the realization of scale invariance selects a unique Hilbert tensor which allows for an easy test as to whether conformal invariance is also realized. Finally we make some basic remarks on metric generally covariant theories and classical field theory in a fixed curved background.

The classical correlation limits the ability of the measurement-induced average coherence

Science.gov (United States)

Zhang, Jun; Yang, Si-Ren; Zhang, Yang; Yu, Chang-Shui

2017-04-01

Coherence is the most fundamental quantum feature in quantum mechanics. For a bipartite quantum state, if a measurement is performed on one party, the other party, based on the measurement outcomes, will collapse to a corresponding state with some probability and hence gain the average coherence. It is shown that the average coherence is not less than the coherence of its reduced density matrix. In particular, it is very surprising that the extra average coherence (and the maximal extra average coherence with all the possible measurements taken into account) is upper bounded by the classical correlation of the bipartite state instead of the quantum correlation. We also find the sufficient and necessary condition for the null maximal extra average coherence. Some examples demonstrate the relation and, moreover, show that quantum correlation is neither sufficient nor necessary for the nonzero extra average coherence within a given measurement. In addition, the similar conclusions are drawn for both the basis-dependent and the basis-free coherence measure.

Receptive fields of locust brain neurons are matched to polarization patterns of the sky.

Science.gov (United States)

Bech, Miklós; Homberg, Uwe; Pfeiffer, Keram

2014-09-22

Many animals, including insects, are able to use celestial cues as a reference for spatial orientation and long-distance navigation [1]. In addition to direct sunlight, the chromatic gradient of the sky and its polarization pattern are suited to serve as orientation cues [2-5]. Atmospheric scattering of sunlight causes a regular pattern of E vectors in the sky, which are arranged along concentric circles around the sun [5, 6]. Although certain insects rely predominantly on sky polarization for spatial orientation [7], it has been argued that detection of celestial E vector orientation may not suffice to differentiate between solar and antisolar directions [8, 9]. We show here that polarization-sensitive (POL) neurons in the brain of the desert locust Schistocerca gregaria can overcome this ambiguity. Extracellular recordings from POL units in the central complex and lateral accessory lobes revealed E vector tunings arranged in concentric circles within large receptive fields, matching the sky polarization pattern at certain solar positions. Modeling of neuronal responses under an idealized sky polarization pattern (Rayleigh sky) suggests that these "matched filter" properties allow locusts to unambiguously determine the solar azimuth by relying solely on the sky polarization pattern for compass navigation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Classical mechanics

CERN Document Server

Benacquista, Matthew J

2018-01-01

This textbook provides an introduction to classical mechanics at a level intermediate between the typical undergraduate and advanced graduate level. This text describes the background and tools for use in the fields of modern physics, such as quantum mechanics, astrophysics, particle physics, and relativity. Students who have had basic undergraduate classical mechanics or who have a good understanding of the mathematical methods of physics will benefit from this book.

Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum Distributions

Directory of Open Access Journals (Sweden)

Ryan eBabbush

2013-10-01

Full Text Available Feynman and Hibbs were the first to variationally determine an effective potential whose associated classical canonical ensemble approximates the exact quantum partition function. We examine the existence of a map between the local potential and an effective classical potential which matches the exact quantum equilibrium density and partition function. The usefulness of such a mapping rests in its ability to readily improve Born-Oppenheimer potentials for use with classical sampling. We show that such a map is unique and must exist. To explore the feasibility of using this result to improve classical molecular mechanics, we numerically produce a map from a library of randomly generated one-dimensional potential/effective potential pairs then evaluate its performance on independent test problems. We also apply the map to simulate liquid para-hydrogen, finding that the resulting radial pair distribution functions agree well with path integral Monte Carlo simulations. The surprising accessibility and transferability of the technique suggest a quantitative route to adapting Born-Oppenheimer potentials, with a motivation similar in spirit to the powerful ideas and approximations of density functional theory.

Classical geometrical interpretation of ghost fields and anomalies in Yang-Mills theory and quantum gravity

International Nuclear Information System (INIS)

Thierry-Mieg, J.

1985-01-01

This paper discusses the reinterpretation of the BRS equations of Quantum Field Theory as the Maurer Cartan equation of a classical principal fiber bundle leads to a simple gauge invariant classification of the anomalies in Yang Mills theory and gravity

Extra-mixing in red giant stars: Challenges for nuclear physics

Energy Technology Data Exchange (ETDEWEB)

Palmerini, Sara; Maiorca, Enrico, E-mail: sara.pamerini@fisica.unipg.i [I.N.F.N. sezione di Perugia Dipartimento di Fisica Universita degli Studi di Perugia, via Pascoli, 06123, Perugia (Italy)

2010-01-01

The existence of extra-mixing phenomena has been often invoked as a possible solution for the Li-abundance puzzle in low-mass red giant stars. In particular, [1] have shown that extra-mixing phenomena induced by stellar magnetic fields can justify the surface Li enrichment as well as its depletion in low mass giants. In the framework of this model, we test here how sensitive is the Li production to the reaction rate for the {sup 7}Be electron capture, in order to establish whether the presence of intense magnetic fields can alter the Li yield.

National extra heavy crude oil upgrade; Melhoramento de petroleos extra pesados nacionais no ambiente de producao

Energy Technology Data Exchange (ETDEWEB)

Medina, Lilian Camen; Zilio, Evaldo L.; Guimarae, Regina C.; Tosta, Luiz C. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Barros, Ricardo S. de [Fundacao Universitaria Jose Bonifacio (FUJB), Rio de Janeiro, RJ (Brazil); Leite, Luiz Fernando T. [PETROBRAS S.A., Vitoria, ES (Brazil). Unidade de Negocios-ES

2008-07-01

Brazilian petroleums are becoming increasingly heavy, reaching values of up to 7 deg API, which classifies them as extra heavy. They are also very viscous, sometimes presenting values as 10184 mm{sup 2}/s to 50 deg C. These two factors affect production operations like lifting, flow assurance and primary processing, with implications on transporting and refining. Trading these kinds of oils is also difficult; once there are not many refineries in the world able to process them. Due to these facts and also to the lower yield on premium products, the international market value is lower than the reference oil, for example, oil 'Brent'. Studies indicate that in some heavy oils fields the process of well lifting and also the flow in pipelines is almost impracticable in a first analysis, mainly offshore field, impacting both technically and economically the development of the production of a new field. Therefore it becomes necessary implement efforts to develop alternatives to increase oil's API density and at the same time reduce the viscosity of extra heavy oil inside the well, i.e. through a process of upgrading assuring its flow and consequently their production, primary processing and refining, increasing, the value of marketing. (author)

Receptivity to alcohol marketing predicts initiation of alcohol use.

Science.gov (United States)

Henriksen, Lisa; Feighery, Ellen C; Schleicher, Nina C; Fortmann, Stephen P

2008-01-01

This longitudinal study examined the influence of alcohol advertising and promotions on the initiation of alcohol use. A measure of receptivity to alcohol marketing was developed from research about tobacco marketing. Recall and recognition of alcohol brand names were also examined. Data were obtained from in-class surveys of sixth, seventh, and eighth graders at baseline and 12-month follow-up. Participants who were classified as never drinkers at baseline (n = 1,080) comprised the analysis sample. Logistic regression models examined the association of advertising receptivity at baseline with any alcohol use and current drinking at follow-up, adjusting for multiple risk factors, including peer alcohol use, school performance, risk taking, and demographics. At baseline, 29% of never drinkers either owned or wanted to use an alcohol branded promotional item (high receptivity), 12% students named the brand of their favorite alcohol ad (moderate receptivity), and 59% were not receptive to alcohol marketing. Approximately 29% of adolescents reported any alcohol use at follow-up; 13% reported drinking at least 1 or 2 days in the past month. Never drinkers who reported high receptivity to alcohol marketing at baseline were 77% more likely to initiate drinking by follow-up than those were not receptive. Smaller increases in the odds of alcohol use at follow-up were associated with better recall and recognition of alcohol brand names at baseline. Alcohol advertising and promotions are associated with the uptake of drinking. Prevention programs may reduce adolescents' receptivity to alcohol marketing by limiting their exposure to alcohol ads and promotions and by increasing their skepticism about the sponsors' marketing tactics.

Principles of physics from quantum field theory to classical mechanics

CERN Document Server

Jun, Ni

2014-01-01

This book starts from a set of common basic principles to establish the formalisms in all areas of fundamental physics, including quantum field theory, quantum mechanics, statistical mechanics, thermodynamics, general relativity, electromagnetic field, and classical mechanics. Instead of the traditional pedagogic way, the author arranges the subjects and formalisms in a logical-sequential way, i.e. all the formulas are derived from the formulas before them. The formalisms are also kept self-contained. Most of the required mathematical tools are also given in the appendices. Although this book covers all the disciplines of fundamental physics, the book is concise and can be treated as an integrated entity. This is consistent with the aphorism that simplicity is beauty, unification is beauty, and thus physics is beauty. The book may be used as an advanced textbook by graduate students. It is also suitable for physicists who wish to have an overview of fundamental physics. Readership: This is an advanced gradua...

Flowing states and vortices in the classical XY model in an external field

International Nuclear Information System (INIS)

Homma, Shigeo; Aoki, Toshizumi; Takeno, Shozo.

1981-01-01

Uniformly flowing states and vortices in the classical XY model in an external field are studied. This is done by using a continuum approximation and by paying attention to particular solutions to nonlinear partial differential equations for two angles theta and phi of rotation of spins for which phi satisfies the Laplace equation. For these two states equations for theta have forms similar to that in the classical Ising model in a transverse field. The uniformly flowing states are therefore described by kink-type excitations identical to those in the two-dimensional Ising model. Phonon modes associated with the uniformly flowing states are also studied, which are similar to Bogoliubov phonons. Vortex solutions and vortex formation energy are studied in close similarity to the case of liquid He 4 . By comparing the energies of these two states, an expression for critical velocity is obtained. By making correspondence to the case of liquid He 4 , numerical values of the critical velocity and of the velocity of phonons around the uniformly flowing states are estimated. For the former the numerical value is in fair agreement with experimental data. (author)

A review of recommendations for sequencing receptive and expressive language instruction.

Science.gov (United States)

Petursdottir, Anna Ingeborg; Carr, James E

2011-01-01

We review recommendations for sequencing instruction in receptive and expressive language objectives in early and intensive behavioral intervention (EIBI) programs. Several books recommend completing receptive protocols before introducing corresponding expressive protocols. However, this recommendation has little empirical support, and some evidence exists that the reverse sequence may be more efficient. Alternative recommendations include teaching receptive and expressive skills simultaneously (M. L. Sundberg & Partington, 1998) and building learning histories that lead to acquisition of receptive and expressive skills without direct instruction (Greer & Ross, 2008). Empirical support for these recommendations also is limited. Future research should assess the relative efficiency of receptive-before-expressive, expressive-before-receptive, and simultaneous training with children who have diagnoses of autism spectrum disorders. In addition, further evaluation is needed of the potential benefits of multiple-exemplar training and other variables that may influence the efficiency of receptive and expressive instruction.

Integrated parallel reception, excitation, and shimming (iPRES).

Science.gov (United States)

Han, Hui; Song, Allen W; Truong, Trong-Kha

2013-07-01

To develop a new concept for a hardware platform that enables integrated parallel reception, excitation, and shimming. This concept uses a single coil array rather than separate arrays for parallel excitation/reception and B0 shimming. It relies on a novel design that allows a radiofrequency current (for excitation/reception) and a direct current (for B0 shimming) to coexist independently in the same coil. Proof-of-concept B0 shimming experiments were performed with a two-coil array in a phantom, whereas B0 shimming simulations were performed with a 48-coil array in the human brain. Our experiments show that individually optimized direct currents applied in each coil can reduce the B0 root-mean-square error by 62-81% and minimize distortions in echo-planar images. The simulations show that dynamic shimming with the 48-coil integrated parallel reception, excitation, and shimming array can reduce the B0 root-mean-square error in the prefrontal and temporal regions by 66-79% as compared with static second-order spherical harmonic shimming and by 12-23% as compared with dynamic shimming with a 48-coil conventional shim array. Our results demonstrate the feasibility of the integrated parallel reception, excitation, and shimming concept to perform parallel excitation/reception and B0 shimming with a unified coil system as well as its promise for in vivo applications. Copyright © 2013 Wiley Periodicals, Inc.

Construction of classical and non-classical coherent photon states

International Nuclear Information System (INIS)

Honegger, Reinhard; Rieckers, Alfred

2001-01-01

It is well known that the diagonal matrix elements of all-order coherent states for the quantized electromagnetic field have to constitute a Poisson distribution with respect to the photon number. The present work gives first the summary of a constructive scheme, developed previously, which determines in terms of an auxiliary Hilbert space all possible off-diagonal elements for the all-order coherent density operators in Fock space and which identifies all extremal coherent states. In terms of this formalism it is then demonstrated that each pure classical coherent state is a uniformly phase locked (quantum) coherent superposition of number states. In a mixed classical coherent state the exponential of the locked phase is shown to be replaced by a rather arbitrary unitary operator in the auxiliary Hilbert space. On the other hand classes for density operators--and for their normally ordered characteristic functions--of non-classical coherent states are obtained, especially by rather weak perturbations of classical coherent states. These illustrate various forms of breaking the classical uniform phase locking and exhibit rather peculiar properties, such as asymmetric fluctuations for the quadrature phase operators. Several criteria for non-classicality are put forward and applied to the elaborated non-classical coherent states, providing counterexamples against too simple arguments for classicality. It is concluded that classicality is only a stable concept for coherent states with macroscopic intensity

33 CFR 158.310 - Reception facilities: General.

Science.gov (United States)

2010-07-01

... order to pass the inspection under § 158.160, must— (1) Be a reception facility as defined under § 158... residue; (5) Be capable of receiving NLS residue from an oceangoing ship within 24 hours after notice by that ship of the need for reception facilities; and (6) Be capable of completing the transfer of NLS...

The media's reception of the risk associated with radioactive disasters

International Nuclear Information System (INIS)

Vettenranta, S.

1996-01-01

There is an urgent need to develop methodologies to examine the response by the media to radioactive disasters. 'Reception study' is a new research approach in the field of mass communication, studying how the viewers construct meaning from TV news. This ongoing reception study explores how fifteen respondents, all involved in the Chernobyl disaster in 1986, recall and interpret TV news coverage nine years after the accident. The main aim is to discover how the news affects the recipients' interpretations of a disaster and what kind of thoughts, reactions and associations risk messages provoke in retrospect, in the present and in the beliefs about the future. The initial findings indicate that the Chernobyl news on TV was mainly based on technical rationality, while viewers construct meaning founded on symbolic, cultural rationality. The transmission of catastrophe news is not just a matter of responding to the information needs of the public. Denotative risk messages simultaneously convey connotative, symbolic resonance of risk on a metaphysical level. (author)

Classical-driving-assisted entanglement dynamics control

Energy Technology Data Exchange (ETDEWEB)

Zhang, Ying-Jie, E-mail: yingjiezhang@qfnu.edu.cn [Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu 273165 (China); Han, Wei [Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu 273165 (China); Xia, Yun-Jie, E-mail: yjxia@qfnu.edu.cn [Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu 273165 (China); Fan, Heng, E-mail: hfan@iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing, 100190 (China)

2017-04-15

We propose a scheme of controlling entanglement dynamics of a quantum system by applying the external classical driving field for two atoms separately located in a single-mode photon cavity. It is shown that, with a judicious choice of the classical-driving strength and the atom–photon detuning, the effective atom–photon interaction Hamiltonian can be switched from Jaynes–Cummings model to anti-Jaynes–Cummings model. By tuning the controllable atom–photon interaction induced by the classical field, we illustrate that the evolution trajectory of the Bell-like entanglement states can be manipulated from entanglement-sudden-death to no-entanglement-sudden-death, from no-entanglement-invariant to entanglement-invariant. Furthermore, the robustness of the initial Bell-like entanglement can be improved by the classical driving field in the leaky cavities. This classical-driving-assisted architecture can be easily extensible to multi-atom quantum system for scalability.

Quantum averaging and resonances: two-level atom in a one-mode classical laser field

Directory of Open Access Journals (Sweden)

M. Amniat-Talab

2007-06-01

Full Text Available   We use a nonperturbative method based on quantum averaging and an adapted from of resonant transformations to treat the resonances of the Hamiltonian of a two-level atom interacting with a one-mode classical field in Floquet formalism. We illustrate this method by extraction of effective Hamiltonians of the system in two regimes of weak and strong coupling. The results obtained in the strong-coupling regime, are valid in the whole range of the coupling constant for the one-photon zero-field resonance.

Mobile television news: a study on the reception of the news on the mobile audience by adults / seniors

Directory of Open Access Journals (Sweden)

Cristiane Finger Costa

2015-08-01

Full Text Available By inserting digital television in Brazil, the programming of open television becomes available in mobile and portable devices without any additional fares. The reception of contents anytime and anywhere is bound to provoke change in the relation between journalists and viewers. For this work, a survey was made in the field of reception to identify, in a qualitative way, the expectations and needs of senior/adult public when watching news in cell phones.

Classic and Quantum Capacitances in Bernal Bilayer and Trilayer Graphene Field Effect Transistor

Directory of Open Access Journals (Sweden)

Hatef Sadeghi

2013-01-01

Full Text Available Our focus in this study is on characterizing the capacitance voltage (C-V behavior of Bernal stacking bilayer graphene (BG and trilayer graphene (TG as the channel of FET devices. The analytical models of quantum capacitance (QC of BG and TG are presented. Although QC is smaller than the classic capacitance in conventional devices, its contribution to the total metal oxide semiconductor capacitor in graphene-based FET devices becomes significant in the nanoscale. Our calculation shows that QC increases with gate voltage in both BG and TG and decreases with temperature with some fluctuations. However, in bilayer graphene the fluctuation is higher due to its tunable band structure with external electric fields. In similar temperature and size, QC in metal oxide BG is higher than metal oxide TG configuration. Moreover, in both BG and TG, total capacitance is more affected by classic capacitance as the distance between gate electrode and channel increases. However, QC is more dominant when the channel becomes thinner into the nanoscale, and therefore we mostly deal with quantum capacitance in top gate in contrast with bottom gate that the classic capacitance is dominant.

Holographic description of 2D conformal block in semi-classical limit

Energy Technology Data Exchange (ETDEWEB)

Chen, Bin [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University, 5 Yiheyuan Rd, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter,5 Yiheyuan Rd, Beijing 100871 (China); Center for High Energy Physics, Peking University, 5 Yiheyuan Rd, Beijing 100871 (China); Wu, Jie-qiang [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University, 5 Yiheyuan Rd, Beijing 100871 (China); Zhang, Jia-ju [Theoretical Physics Division, Institute of High Energy Physics,Chinese Academy of Sciences, 19B Yuquan Rd, Beijing 100049 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences,19B Yuquan Rd, Beijing 100049 (China)

2016-10-20

In this paper, we study the holographic descriptions of the conformal block of heavy operators in two-dimensional large c conformal field theory. We consider the case that the operators are pairwise inserted such that the distance between the operators in a pair is much smaller than the others. In this case, each pair of heavy operators creates a conical defect in the bulk. We propose that the conformal block is dual to the on-shell action of three dimensional geometry with conical defects in the semi-classical limit. We show that the variation of the on-shell action with respect to the conical angle is equal to the length of the corresponding conical defect. We derive this differential relation on the conformal block in the field theory by introducing two extra light operators as both the probe and the perturbation. Our study also suggests that the area law of the holographic Rényi entropy must holds for a large class of states generated by a finite number of heavy operators insertion.

Zero-point length, extra-dimensions and string T-duality

OpenAIRE

Spallucci, Euro; Fontanini, Michele

2005-01-01

In this paper, we are going to put in a single consistent framework apparently unrelated pieces of information, i.e. zero-point length, extra-dimensions, string T-duality. More in details we are going to introduce a modified Kaluza-Klein theory interpolating between (high-energy) string theory and (low-energy) quantum field theory. In our model zero-point length is a four dimensional ``virtual memory'' of compact extra-dimensions length scale. Such a scale turns out to be determined by T-dual...

Rethinking clinical language mapping approaches: discordant receptive and expressive hemispheric language dominance in epilepsy surgery candidates.

Science.gov (United States)

Gage, Nicole M; Eliashiv, Dawn S; Isenberg, Anna L; Fillmore, Paul T; Kurelowech, Lacey; Quint, Patti J; Chung, Jeffrey M; Otis, Shirley M

2011-06-01

Neuroimaging studies have shed light on cortical language organization, with findings implicating the left and right temporal lobes in speech processing converging to a left-dominant pattern. Findings highlight the fact that the state of theoretical language knowledge is ahead of current clinical language mapping methods, motivating a rethinking of these approaches. The authors used magnetoencephalography and multiple tasks in seven candidates for resective epilepsy surgery to investigate language organization. The authors scanned 12 control subjects to investigate the time course of bilateral receptive speech processes. Laterality indices were calculated for left and right hemisphere late fields ∼150 to 400 milliseconds. The authors report that (1) in healthy adults, speech processes activated superior temporal regions bilaterally converging to a left-dominant pattern, (2) in four of six patients, this was reversed, with bilateral processing converging to a right-dominant pattern, and (3) in three of four of these patients, receptive and expressive language processes were laterally discordant. Results provide evidence that receptive and expressive language may have divergent hemispheric dominance. Right-sided receptive language dominance in epilepsy patients emphasizes the need to assess both receptive and expressive language. Findings indicate that it is critical to use multiple tasks tapping separable aspects of language function to provide sensitive and specific estimates of language localization in surgical patients.

Cold neutron interaction with a classical electric field: Some basic theoretical and experimental considerations

International Nuclear Information System (INIS)

Bruce, S.; Diaz-Valdes, J.; Bennun, L.; Minning, P.C.

2008-01-01

We explore the feasibility of performing an experiment to measure the interaction of cold neutrons with a given classical electric field. Bound and scattering states could be detected by means of an approximate Aharonov-Casher configuration. The theoretical background is presented and then some primary elements for building a neutron detector of this nature are proposed

Metastable gravity on classical defects

International Nuclear Information System (INIS)

Ringeval, Christophe; Rombouts, Jan-Willem

2005-01-01

We discuss the realization of metastable gravity on classical defects in infinite-volume extra dimensions. In dilatonic Einstein gravity, it is found that the existence of metastable gravity on the defect core requires violation of the dominant energy condition for codimension N c =2 defects. This is illustrated with a detailed analysis of a six-dimensional hyperstring minimally coupled to dilaton gravity. We present the general conditions under which a codimension N c >2 defect admits metastable modes, and find that they differ from lower codimensional models in that, under certain conditions, they do not require violation of energy conditions to support quasilocalized gravity

Classical study of the rovibrational dynamics of a polar diatomic molecule in static electric fields

Energy Technology Data Exchange (ETDEWEB)

Inarrea, Manuel, E-mail: manuel.inarrea@unirioja.e [Area de Fisica, Universidad de la Rioja, E-26006 Logrono (Spain); Salas, J. Pablo [Area de Fisica, Universidad de la Rioja, E-26006 Logrono (Spain); Gonzalez-Ferez, Rosario [Instituto ' Carlos I' de Fisica Teorica y Computacional, Universidad de Granada, E-18071 Granada (Spain); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Schmelcher, Peter [Theoretische Chemie, Physikalisch-Chemisches Institut, D-69120 Heidelberg (Germany); Physikalisches Institut, Universitaet Heidelberg, D-69120 Heidelberg (Germany)

2010-01-04

We study the classical dynamics of a polar diatomic molecule in the presence of a strong static homogeneous electric field. Our full rovibrational investigation includes the interaction with the field due to the permanent electric dipole moment and the polarizability of the molecule. Using the LiCs molecule as a prototype, we explore the stability of the equilibrium points and their bifurcations as the field strength is increased. The phase space structure and its dependence on the energy and field strength are analyzed in detail. We demonstrate that depending on the field strength and on the energy, the phase space is characterized either by regular features or by small stochastic layers of chaotic motion.

On gravity's role in the genesis of rest masses of classical fields

Science.gov (United States)

Szabados, László B.

2018-03-01

It is shown that in the Einstein-conformally coupled Higgs-Maxwell system with Friedman-Robertson-Walker symmetries the energy density of the Higgs field has stable local minimum only if the mean curvature of the t=const hypersurfaces is less than a finite critical value χ _c, while for greater mean curvature the energy density is not bounded from below. Therefore, there are extreme gravitational situations in which even quasi-locally defined instantaneous vacuum states of the Higgs sector cannot exist, and hence one cannot at all define the rest mass of all the classical fields. On hypersurfaces with mean curvature less than χ _c the energy density has the `wine bottle' (rather than the familiar `Mexican hat') shape, and the gauge field can get rest mass via the Brout-Englert-Higgs mechanism. The spacelike hypersurface with the critical mean curvature represents the moment of `genesis' of rest masses.

Field development planning for an offshore extra heavy oil in the Gulf of Mexico

Energy Technology Data Exchange (ETDEWEB)

Hernandez-Garcia, G.; Anguiano-Rojas, J. [PEMEX Exploration and Production, Mexico City (Mexico)

2009-07-01

This paper presented a phased development strategy for an offshore extra-heavy oil development located in the Gulf of Mexico. The Ayatsil-1 oil field is located in an upper Cretaceous brecciated formation. One of the primary concerns of the project is the infrastructure that is needed to handle low reservoir temperatures and high viscosity, low gravity API oil. A delineation well was drilled in order to confirm the areal extension of the reservoir. The field contains an estimated 3.1 billion barrels of oil-in-place. The project will involve the installation of fixed platforms and production platforms. Electric submersible pumps (ESPs) and multiphase pumps will be used to transport the oil from between 17 to 25 wells. Analyses were conducted to determine transport mechanisms as well as gathering networks in both stationary and transitory regimes. The viscosity of live and dead oil in the reservoirs must be accurately measured in relation to temperature in order to define the artificial systems that will be used to reduce viscosity. Results from several studies will be used to determine the feasibility of various chemical, thermal, and diluent applications. 6 refs., 3 figs.

Generation of longitudinal current by a transverse electromagnetic field in classical and quantum plasmas

Energy Technology Data Exchange (ETDEWEB)

Latyshev, A. V., E-mail: avlatyshev@mail.ru; Yushkanov, A. A. [Moscow State Regional University (Russian Federation)

2015-09-15

A distribution function for collisionless plasma is derived from the Vlasov kinetic equation in the quadratic approximation with respect to the electromagnetic field. Formulas for calculation of the electric current at an arbitrary temperature (arbitrary degree of degeneration of the electron gas) are deduced. The case of small wavenumbers is considered. It is shown that nonlinearity leads to the generation of an electric current directed along the wave vector. This longitudinal current is orthogonal to the classical transverse current, well known in the linear theory. A distribution function for collisionless quantum plasma is derived from the kinetic equation with the Wigner integral in the quadratic approximation with respect to the vector potential. Formulas for calculation of the electric current at an arbitrary temperature are deduced. The case of small wavenumbers is considered. It is shown that, at small values of the wavenumber, the value of the longitudinal current for quantum plasma coincides with that for classical plasma. The dimensionless currents in quantum and classical plasmas are compared graphically.

New Year’s reception

CERN Multimedia

2009-01-01

At a reception on 28 January, the CERN management presented their best wishes for 2009 to politicians and representatives of the administrations in the local area, and diplomats representing CERN’s Member States, Observer States and other countries.

The reception of Bollywood in Malaysia (1991-2012): a contextual study

OpenAIRE

Sreekumar, Rohini

2017-01-01

Bollywood films are increasingly drawing scholarly attention for their global appeal and reception. Transnational studies have examined the reception of Bollywood in Australia, Britain, Scotland, South Africa, Russia, the United States of America, Bangladesh and Nepal. However, academic work on the Southeast Asian reception of these films is scarcer. This research seeks to fill this gap by looking at the reception of Bollywood in Malaysia from 1991-2012. The thesis adopts a...

The classical centre-of-mass separation for two particles in a homogeneous magnetic field

International Nuclear Information System (INIS)

Dickinson, A.S.; Patterson, J.M.

1986-01-01

The authors investigate classically the problem of the centre-of-mass separation for a two-body system with net charge in a homogeneous magnetic field. Particular attention is paid to the case where one particle is much heavier than the other. Alternative momenta involving a suggested near-constant of the motion are investigated for use with a translation-invariant internal potential. These lead to a 'near separation' in terms of two coupled particles characterised by vectors which possess a simple classical interpretation, even in the presence of an interaction potential. However it is found that the coupling is not small and is not reduced when one of the particles is much heavier than the other, although the frequencies of the two motions then differ widely. (author)

Differential Receptive Field Properties of Parvalbumin and Somatostatin Inhibitory Neurons in Mouse Auditory Cortex.

Science.gov (United States)

Li, Ling-Yun; Xiong, Xiaorui R; Ibrahim, Leena A; Yuan, Wei; Tao, Huizhong W; Zhang, Li I

2015-07-01

Cortical inhibitory circuits play important roles in shaping sensory processing. In auditory cortex, however, functional properties of genetically identified inhibitory neurons are poorly characterized. By two-photon imaging-guided recordings, we specifically targeted 2 major types of cortical inhibitory neuron, parvalbumin (PV) and somatostatin (SOM) expressing neurons, in superficial layers of mouse auditory cortex. We found that PV cells exhibited broader tonal receptive fields with lower intensity thresholds and stronger tone-evoked spike responses compared with SOM neurons. The latter exhibited similar frequency selectivity as excitatory neurons. The broader/weaker frequency tuning of PV neurons was attributed to a broader range of synaptic inputs and stronger subthreshold responses elicited, which resulted in a higher efficiency in the conversion of input to output. In addition, onsets of both the input and spike responses of SOM neurons were significantly delayed compared with PV and excitatory cells. Our results suggest that PV and SOM neurons engage in auditory cortical circuits in different manners: while PV neurons may provide broadly tuned feedforward inhibition for a rapid control of ascending inputs to excitatory neurons, the delayed and more selective inhibition from SOM neurons may provide a specific modulation of feedback inputs on their distal dendrites. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Theoretical physics 3. Classical field theory. On electrodynamics, non-Abelian gauge theories, and gravitation. 3. ed.

International Nuclear Information System (INIS)

Scheck, Florian

2010-01-01

Stringent presentation of field theory, mediates the connection from the classicalelectrodynamics up to modern gauge theories. The compact presentation is ideal for the bachelor study. New chapter on general relativity theory. Deepens the learned by numerous application from laser physic, metamaterials and different more. Theoretical physics 3. Classical field theory. On electrodynamics, non-Abelian, and gravitation is the third of five volumes on theoretical physics by professor Scheck. The cycle theoretical physics comprehends: Volume 1: Mechanics. From Newtons law to the deterministic chaos. Volume 2: Nonrelativistic quantum theory. From the hydrogen atom to the many-particle systems. Volume 3: Classical field theory. From the electrodynamics to the gauge theories. Volume 5: From the laws of thermodynamics to the quantum statistics. This textbook mediates modern theoretical physics in string presentation illustrated by many examples. It contains numerous problems with solution hints ore exemplary, complete solutions. The third edition was revised in many single topics, especially the chapter on general relativity theory was supplemented by an extensive analysis of the Schwarzschild solution. [de

Current Writing: Text and Reception in Southern Africa: Advanced ...

African Journals Online (AJOL)

Current Writing: Text and Reception in Southern Africa: Advanced Search. Journal Home > Current Writing: Text and Reception in Southern Africa: Advanced Search. Log in or Register to get access to full text downloads.

Algebraic construction of interacting higher spin field theories

International Nuclear Information System (INIS)

Fougere, F.

1991-10-01

We develop a general framework which we believe may provide some insights into the structure of interacting 'high spin' field theories. A finite or infinite set of classical spin fields is described by means of a field defined on an enlarged spacetime manifold. The free action and its gauge symmetries are gathered into a nilpotent differential operator on this manifold. In particular, the choice of Grassmann-valued extra coordinates leads to theories involving only a finite set of fields, the possible contents (spin multiplicities, degree of reducibility, etc.) of which are classified according to the representations of a unitary algebra. The interacting theory is characterized by a functional of the field on the enlarged manifold. We show that there is among these functionals a natural graded Lie algebra structure allowing one to rewrite the gauge invariance condition of the action in a concise form which is a nonlinear generalization of the nilpotency condition of the free theory. We obtain the general solution of this 'classical master equation' , which can be built recurrently starting form the cubic vertex, and we study its symmetries. Our formalism lends itself to a systematic introduction of additional conditions, such as locality, polynomiality, etc. We write down the general form of the solutions exhibiting a scale invariance. The case of a spin 1 field yields, as a unique solution, Yang-Mills theory. In view of quantization, we show that the solution of the classical master equation straightforwardly provides a solution of the (quantum) Batalin-Vilkoviski master equation. One may then obtain a gauge fixed action in the usual way

Transition Prediction in Hypersonic Boundary Layers Using Receptivity and Freestream Spectra

Science.gov (United States)

Balakumar, P.; Chou, Amanda

2016-01-01

Boundary-layer transition in hypersonic flows over a straight cone can be predicted using measured freestream spectra, receptivity, and threshold values for the wall pressure fluctuations at the transition onset points. Simulations are performed for hypersonic boundary-layer flows over a 7-degree half-angle straight cone with varying bluntness at a freestream Mach number of 10. The steady and the unsteady flow fields are obtained by solving the two-dimensional Navier-Stokes equations in axisymmetric coordinates using a 5th-order accurate weighted essentially non-oscillatory (WENO) scheme for space discretization and using a third-order total-variation-diminishing (TVD) Runge-Kutta scheme for time integration. The calculated N-factors at the transition onset location increase gradually with increasing unit Reynolds numbers for flow over a sharp cone and remain almost the same for flow over a blunt cone. The receptivity coefficient increases slightly with increasing unit Reynolds numbers. They are on the order of 4 for a sharp cone and are on the order of 1 for a blunt cone. The location of transition onset predicted from the simulation including the freestream spectrum, receptivity, and the linear and the weakly nonlinear evolutions yields a solution close to the measured onset location for the sharp cone. The simulations over-predict transition onset by about twenty percent for the blunt cone.

Morning Receptions in a Danish ECE Context

DEFF Research Database (Denmark)

Kornerup, Ida; Gravgaard, Mette Lykke

This paper focus on a special pedagogical context; morning receptions as a learning environment. The studies of mornings are part of a 3 year long research project in which different types of learning environments were investigated. Few studies have researched morning receptions in this perspecti...... even though pedagogues often emphasize that this particular pedagogical context have implications on the children’s wellbeing and learning possibilities throughout the day....

Transducer project and optimization of the ultra low magnetic field NMR tomograph reception system system

International Nuclear Information System (INIS)

Vidoto, Edson Luiz Gea

1995-01-01

The aim of the present work was to optimize the signal to noise ratio in our NMR imaging system (TORM 005) by improving transducer's reception quality through better designed coils, balanced tuning circuit for this coils and power decoupling circuits and by reducing interference from the electromagnetic environment. For this purpose, we had to modify the internal electromagnetic shielding and incorporate line filters in the more critical signals paths. Also, new types of coils were developed, improving the signal to noise ratio, and allowing us to make clinical exams with superior quality for several anatomies. Balanced circuits for tuning and matching of the coil were studied and built, allowing a reduction of the coil losses because patient's load. This produced a more reliable coil tuning after positioning each new patient. Circuits to avoid the receiver input overload and decoupling circuits for the isolation of receiver coils from excitation coil were designed and incorporated to the TORM 005. All these alterations of our imaging system (TORM 005) contributed to a significant improvement in the signal to noise ratio, reliability and reproducibility of the system. This permitted to operate the system routinely for clinical applications, research and development in the area of ultra low magnetic field tomography. (author)

Comparison of Measures of E-cigarette Advertising Exposure and Receptivity.

Science.gov (United States)

Pokhrel, Pallav; Fagan, Pebbles; Herzog, Thaddeus A; Schmid, Simone; Kawamoto, Crissy T; Unger, Jennifer B

2017-10-01

We tested how various measures of e-cigarette advertising exposure and receptivity are related to each other and compare to each other in their associations with e-cigarette use susceptibility and behavior. Cross-sectional data were collected from young adult college students (N = 470; M age = 20.9, SD = 2.1; 65% women). Measures of e-cigarette advertising exposure/receptivity compared included a cued recall measure, measures of marketing receptivity, perceived ad exposure, liking of e-cigarette ads, and frequency of convenience store visit, which is considered a measure of point-of-sale ad exposure. The cued-recall measure was associated with e-cigarette use experimentation but not current e-cigarette use. Marketing receptivity was associated with current e-cigarette use but not e-cigarette use experimentation. Liking of e-cigarette ads was the only measure associated with e-cigarette use susceptibility. Frequency of convenience store visit was associated with current e-cigarette use but not e-cigarette use experimentation or susceptibility. Inclusion of multiple measures of marketing exposure and receptivity is recommended for regulatory research concerning e-cigarette marketing. Marketing receptivity and cued recall measures are strong correlates of current and ever e-cigarette use, respectively.

Classical nucleation theory in the phase-field crystal model.

Science.gov (United States)

Jreidini, Paul; Kocher, Gabriel; Provatas, Nikolas

2018-04-01

A full understanding of polycrystalline materials requires studying the process of nucleation, a thermally activated phase transition that typically occurs at atomistic scales. The numerical modeling of this process is problematic for traditional numerical techniques: commonly used phase-field methods' resolution does not extend to the atomic scales at which nucleation takes places, while atomistic methods such as molecular dynamics are incapable of scaling to the mesoscale regime where late-stage growth and structure formation takes place following earlier nucleation. Consequently, it is of interest to examine nucleation in the more recently proposed phase-field crystal (PFC) model, which attempts to bridge the atomic and mesoscale regimes in microstructure simulations. In this work, we numerically calculate homogeneous liquid-to-solid nucleation rates and incubation times in the simplest version of the PFC model, for various parameter choices. We show that the model naturally exhibits qualitative agreement with the predictions of classical nucleation theory (CNT) despite a lack of some explicit atomistic features presumed in CNT. We also examine the early appearance of lattice structure in nucleating grains, finding disagreement with some basic assumptions of CNT. We then argue that a quantitatively correct nucleation theory for the PFC model would require extending CNT to a multivariable theory.

Classical nucleation theory in the phase-field crystal model

Science.gov (United States)

Jreidini, Paul; Kocher, Gabriel; Provatas, Nikolas

2018-04-01

A full understanding of polycrystalline materials requires studying the process of nucleation, a thermally activated phase transition that typically occurs at atomistic scales. The numerical modeling of this process is problematic for traditional numerical techniques: commonly used phase-field methods' resolution does not extend to the atomic scales at which nucleation takes places, while atomistic methods such as molecular dynamics are incapable of scaling to the mesoscale regime where late-stage growth and structure formation takes place following earlier nucleation. Consequently, it is of interest to examine nucleation in the more recently proposed phase-field crystal (PFC) model, which attempts to bridge the atomic and mesoscale regimes in microstructure simulations. In this work, we numerically calculate homogeneous liquid-to-solid nucleation rates and incubation times in the simplest version of the PFC model, for various parameter choices. We show that the model naturally exhibits qualitative agreement with the predictions of classical nucleation theory (CNT) despite a lack of some explicit atomistic features presumed in CNT. We also examine the early appearance of lattice structure in nucleating grains, finding disagreement with some basic assumptions of CNT. We then argue that a quantitatively correct nucleation theory for the PFC model would require extending CNT to a multivariable theory.

On covariant Poisson brackets in classical field theory

International Nuclear Information System (INIS)

Forger, Michael; Salles, Mário O.

2015-01-01

How to give a natural geometric definition of a covariant Poisson bracket in classical field theory has for a long time been an open problem—as testified by the extensive literature on “multisymplectic Poisson brackets,” together with the fact that all these proposals suffer from serious defects. On the other hand, the functional approach does provide a good candidate which has come to be known as the Peierls–De Witt bracket and whose construction in a geometrical setting is now well understood. Here, we show how the basic “multisymplectic Poisson bracket” already proposed in the 1970s can be derived from the Peierls–De Witt bracket, applied to a special class of functionals. This relation allows to trace back most (if not all) of the problems encountered in the past to ambiguities (the relation between differential forms on multiphase space and the functionals they define is not one-to-one) and also to the fact that this class of functionals does not form a Poisson subalgebra

On covariant Poisson brackets in classical field theory

Energy Technology Data Exchange (ETDEWEB)

Forger, Michael [Instituto de Matemática e Estatística, Universidade de São Paulo, Caixa Postal 66281, BR–05315-970 São Paulo, SP (Brazil); Salles, Mário O. [Instituto de Matemática e Estatística, Universidade de São Paulo, Caixa Postal 66281, BR–05315-970 São Paulo, SP (Brazil); Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Campus Universitário – Lagoa Nova, BR–59078-970 Natal, RN (Brazil)

2015-10-15

How to give a natural geometric definition of a covariant Poisson bracket in classical field theory has for a long time been an open problem—as testified by the extensive literature on “multisymplectic Poisson brackets,” together with the fact that all these proposals suffer from serious defects. On the other hand, the functional approach does provide a good candidate which has come to be known as the Peierls–De Witt bracket and whose construction in a geometrical setting is now well understood. Here, we show how the basic “multisymplectic Poisson bracket” already proposed in the 1970s can be derived from the Peierls–De Witt bracket, applied to a special class of functionals. This relation allows to trace back most (if not all) of the problems encountered in the past to ambiguities (the relation between differential forms on multiphase space and the functionals they define is not one-to-one) and also to the fact that this class of functionals does not form a Poisson subalgebra.

The media`s reception of the risk associated with radioactive disasters

Energy Technology Data Exchange (ETDEWEB)

Vettenranta, S. [Norwegian University of Science and Technology, Dragvoll (Norway). Dept. of edcation

1996-12-31

There is an urgent need to develop methodologies to examine the response by the media to radioactive disasters. `Reception study` is a new research approach in the field of mass communication, studying how the viewers construct meaning from TV news. This ongoing reception study explores how fifteen respondents, all involved in the Chernobyl disaster in 1986, recall and interpret TV news coverage nine years after the accident. The main aim is to discover how the news affects the recipients` interpretations of a disaster and what kind of thoughts, reactions and associations risk messages provoke in retrospect, in the present and in the beliefs about the future. The initial findings indicate that the Chernobyl news on TV was mainly based on technical rationality, while viewers construct meaning founded on symbolic, cultural rationality. The transmission of catastrophe news is not just a matter of responding to the information needs of the public. Denotative risk messages simultaneously convey connotative, symbolic resonance of risk on a metaphysical level. (author).

Predicting bias in perceived position using attention field models

NARCIS (Netherlands)

Klein, Barrie P; Paffen, Chris L E; Pas, Susan F Te; Dumoulin, Serge O

2016-01-01

Attention is the mechanism through which we select relevant information from our visual environment. We have recently demonstrated that attention attracts receptive fields across the visual hierarchy (Klein, Harvey, & Dumoulin, 2014). We captured this receptive field attraction using an attention

Bioinspired magnetic reception and multimodal sensing.

Science.gov (United States)

Taylor, Brian K

2017-08-01

Several animals use Earth's magnetic field in concert with other sensor modes to accomplish navigational tasks ranging from local homing to continental scale migration. However, despite extensive research, animal magnetic reception remains poorly understood. Similarly, the Earth's magnetic field offers a signal that engineered systems can leverage to navigate in environments where man-made positioning systems such as GPS are either unavailable or unreliable. This work uses a behavioral strategy inspired by the migratory behavior of sea turtles to locate a magnetic goal and respond to wind when it is present. Sensing is performed using a number of distributed sensors. Based on existing theoretical biology considerations, data processing is performed using combinations of circles and ellipses to exploit the distributed sensing paradigm. Agent-based simulation results indicate that this approach is capable of using two separate magnetic properties to locate a goal from a variety of initial conditions in both noiseless and noisy sensory environments. The system's ability to locate the goal appears robust to noise at the cost of overall path length.

Semi-classical noise investigation for sub-40nm metal-oxide-semiconductor field-effect transistors

International Nuclear Information System (INIS)

Spathis, C.; Birbas, A.; Georgakopoulou, K.

2015-01-01

Device white noise levels in short channel Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) dictate the performance and reliability of high-frequency circuits ranging from high-speed microprocessors to Low-Noise Amplifiers (LNAs) and microwave circuits. Recent experimental noise measurements with very short devices demonstrate the existence of suppressed shot noise, contrary to the predictions of classical channel thermal noise models. In this work we show that, as the dimensions continue to shrink, shot noise has to be considered when the channel resistance becomes comparable to the barrier resistance at the source-channel junction. By adopting a semi-classical approach and taking retrospectively into account transport, short-channel and quantum effects, we investigate the partitioning between shot and thermal noise, and formulate a predictive model that describes the noise characteristics of modern devices

Semi-classical noise investigation for sub-40nm metal-oxide-semiconductor field-effect transistors

Energy Technology Data Exchange (ETDEWEB)

Spathis, C., E-mail: cspathis@ece.upatras.gr; Birbas, A.; Georgakopoulou, K. [Department of Electrical and Computer Engineering, University of Patras, Patras 26500 (Greece)

2015-08-15

Device white noise levels in short channel Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) dictate the performance and reliability of high-frequency circuits ranging from high-speed microprocessors to Low-Noise Amplifiers (LNAs) and microwave circuits. Recent experimental noise measurements with very short devices demonstrate the existence of suppressed shot noise, contrary to the predictions of classical channel thermal noise models. In this work we show that, as the dimensions continue to shrink, shot noise has to be considered when the channel resistance becomes comparable to the barrier resistance at the source-channel junction. By adopting a semi-classical approach and taking retrospectively into account transport, short-channel and quantum effects, we investigate the partitioning between shot and thermal noise, and formulate a predictive model that describes the noise characteristics of modern devices.

Receptivity of Hypersonic Boundary Layers to Distributed Roughness and Acoustic Disturbances

Science.gov (United States)

Balakumar, P.

2013-01-01

Boundary-layer receptivity and stability of Mach 6 flows over smooth and rough seven-degree half-angle sharp-tipped cones are numerically investigated. The receptivity of the boundary layer to slow acoustic disturbances, fast acoustic disturbances, and vortical disturbances is considered. The effects of three-dimensional isolated roughness on the receptivity and stability are also simulated. The results for the smooth cone show that the instability waves are generated in the leading edge region and that the boundary layer is much more receptive to slow acoustic waves than to the fast acoustic waves. Vortical disturbances also generate unstable second modes, however the receptivity coefficients are smaller than that of the slow acoustic wave. Distributed roughness elements located near the nose region decreased the receptivity of the second mode generated by the slow acoustic wave by a small amount. Roughness elements distributed across the continuous spectrum increased the receptivity of the second mode generated by the slow and fast acoustic waves and the vorticity wave. The largest increase occurred for the vorticity wave. Roughness elements distributed across the synchronization point did not change the receptivity of the second modes generated by the acoustic waves. The receptivity of the second mode generated by the vorticity wave increased in this case, but the increase is lower than that occurred with the roughness elements located across the continuous spectrum. The simulations with an isolated roughness element showed that the second mode waves generated by the acoustic disturbances are not influenced by the small roughness element. Due to the interaction, a three-dimensional wave is generated. However, the amplitude is orders of magnitude smaller than the two-dimensional wave.

Thermodynamic properties for applications in chemical industry via classical force fields.

Science.gov (United States)

Guevara-Carrion, Gabriela; Hasse, Hans; Vrabec, Jadran

2012-01-01

Thermodynamic properties of fluids are of key importance for the chemical industry. Presently, the fluid property models used in process design and optimization are mostly equations of state or G (E) models, which are parameterized using experimental data. Molecular modeling and simulation based on classical force fields is a promising alternative route, which in many cases reasonably complements the well established methods. This chapter gives an introduction to the state-of-the-art in this field regarding molecular models, simulation methods, and tools. Attention is given to the way modeling and simulation on the scale of molecular force fields interact with other scales, which is mainly by parameter inheritance. Parameters for molecular force fields are determined both bottom-up from quantum chemistry and top-down from experimental data. Commonly used functional forms for describing the intra- and intermolecular interactions are presented. Several approaches for ab initio to empirical force field parameterization are discussed. Some transferable force field families, which are frequently used in chemical engineering applications, are described. Furthermore, some examples of force fields that were parameterized for specific molecules are given. Molecular dynamics and Monte Carlo methods for the calculation of transport properties and vapor-liquid equilibria are introduced. Two case studies are presented. First, using liquid ammonia as an example, the capabilities of semi-empirical force fields, parameterized on the basis of quantum chemical information and experimental data, are discussed with respect to thermodynamic properties that are relevant for the chemical industry. Second, the ability of molecular simulation methods to describe accurately vapor-liquid equilibrium properties of binary mixtures containing CO(2) is shown.

The classical limit of W-algebras

International Nuclear Information System (INIS)

Figueroa-O'Farrill, J.M.; Ramos, E.

1992-01-01

We define and compute explicitly the classical limit of the realizations of W n appearing as hamiltonian structures of generalized KdV hierarchies. The classical limit is obtained by taking the commutative limit of the ring of pseudodifferential operators. These algebras - denoted w n - have free field realizations in which the generators are given by the elementary symmetric polynomials in the free fields. We compute the algebras explicitly and we show that they are all reductions of a new algebra w KP , which is proposed as the universal classical W-algebra for the w n series. As a deformation of this algebra we also obtain w 1+∞ , the classical limit of W 1+∞ . (orig.)

Fermions from classical statistics

International Nuclear Information System (INIS)

Wetterich, C.

2010-01-01

We describe fermions in terms of a classical statistical ensemble. The states τ of this ensemble are characterized by a sequence of values one or zero or a corresponding set of two-level observables. Every classical probability distribution can be associated to a quantum state for fermions. If the time evolution of the classical probabilities p τ amounts to a rotation of the wave function q τ (t)=±√(p τ (t)), we infer the unitary time evolution of a quantum system of fermions according to a Schroedinger equation. We establish how such classical statistical ensembles can be mapped to Grassmann functional integrals. Quantum field theories for fermions arise for a suitable time evolution of classical probabilities for generalized Ising models.

The Comparative Reception of Darwinism: A Brief History

Science.gov (United States)

Glick, Thomas F.

2010-01-01

The subfield of Darwin studies devoted to comparative reception coalesced around 1971 with the planning of a conference on the subject, at the University of Texas at Austin held in April 1972. The original focus was western Europe, Russia and the United States. Subsequently a spate of studies on the Italian reception added to the Eurocentric…

Reproducing Quantum Probability Distributions at the Speed of Classical Dynamics: A New Approach for Developing Force-Field Functors.

Science.gov (United States)

Sundar, Vikram; Gelbwaser-Klimovsky, David; Aspuru-Guzik, Alán

2018-04-05

Modeling nuclear quantum effects is required for accurate molecular dynamics (MD) simulations of molecules. The community has paid special attention to water and other biomolecules that show hydrogen bonding. Standard methods of modeling nuclear quantum effects like Ring Polymer Molecular Dynamics (RPMD) are computationally costlier than running classical trajectories. A force-field functor (FFF) is an alternative method that computes an effective force field that replicates quantum properties of the original force field. In this work, we propose an efficient method of computing FFF using the Wigner-Kirkwood expansion. As a test case, we calculate a range of thermodynamic properties of Neon, obtaining the same level of accuracy as RPMD, but with the shorter runtime of classical simulations. By modifying existing MD programs, the proposed method could be used in the future to increase the efficiency and accuracy of MD simulations involving water and proteins.

External field-induced chaos in classical and quantum Hamiltonian systems

International Nuclear Information System (INIS)

Lin, W.C.

1986-01-01

Classical nonlinear nonintegrable systems exhibit dense sets of resonance zones in phase space. Global chaotic motion appears when neighboring resonance zones overlap. The chaotic motion signifies the destruction of a quasi constant of motion. The motion of a particle, trapped in one of the wells of a sinusoidal, potential driven by a monochromatic external field was studied. Global chaotic behavior sets in when the amplitude of the external field reaches a critical value. The particle then escapes the well. The critical values are found to be in good agreement with a resonance overlap criterion rather than a renormalization-group scheme. A similar system was then studied, but with the particle being confined in an infinite square well potential instead. A stochastic layer is found in the low-energy part of the phase space. The resonance zone structure is found to be in excellent agreement with predictions. The critical values for the onset of global chaotic behavior are found to be in excellent agreement with the renormalization group scheme. The quantum version of the second model above was then considered. In a similar fashion, the external field induces quantum resonance zones. The spectral statistics were computed, and a transition of statistics from Poissonian to Wigner-like was found as overlap of quantum resonances occurs. This also signifies the destruction of a quasi-constant of motion

Investigation of the extra-extra-push by pre-scission neutron measurements with DEMON

International Nuclear Information System (INIS)

Rudolf, Gerard

1998-01-01

The objective of this talk is to present a simple method to calculate pre- and post-scission neutron multiplicities in the frame of the Bass model. This method is of particular interest for very heavy systems for which an extra-extra-push is supposed to hinder fusion. The multiplicities calculated by the model are compared to published data covering a broad range of projectile and target masses, and to more recent ones obtained with the help of the Demon detector and addressing specifically the existence of the extra-extra-push

Casimir Energy, Extra Dimensions and Exotic Propulsion

Science.gov (United States)

Obousy, R.; Saharian, A.

It is well known that the Casimir effect is an excellent candidate for the stabilization of the extra dimensions. It has also been suggested that the Casimir effect in higher dimensions may be the underlying phenomenon that is responsible for the dark energy which is currently driving the accelerated expansion of the universe. In this paper we suggest that, in principle, it may be possible to directly manipulate the size of an extra dimension locally using Standard Model fields in the next generation of particle accelerators. This adjustment of the size of the higher dimension could serve as a technological mechanism to locally adjust the dark energy density and change the local expansion of spacetime. This idea holds tantalizing possibilities in the context of exotic spacecraft propulsion.

Searches for dark matter and extra dimensions with the ATLAS detector

CERN Document Server

Clement, C; The ATLAS collaboration

2014-01-01

Different approaches to finding evidence for dark matter at the LHC are presented. These include searches for events with large missing transverse momentum and a single jet, photon or W/Z boson. Searches for hidden sectors in events with long-lived particles resulting in displaced hadronic vertices or lepton-jet signatures are also reported. Finally, studies sensitive to the presence of extra spatial dimensions are described, as for example classical and quantum black holes and other non-resonant phenomena. Results from sqrt(s) = 8 TeV data taking are presented.

Searches for dark matter and extra dimensions with the ATLAS detector

CERN Document Server

Kruskal, M; The ATLAS collaboration

2015-01-01

Different approaches to finding evidence for dark matter at the LHC are presented. These include searches for events with large missing transverse momentum and a single jet, photon or W/Z boson. Searches for hidden sectors in events with long-lived particles resulting in displaced hadronic vertices or lepton-jet signatures are also reported. Finally, studies sensitive to the presence of extra spatial dimensions are described, as for example classical and quantum black holes and other non-resonant phenomena. Results from $\\sqrt{s}=8$ TeV data taking are presented.

Reward value-based gain control: divisive normalization in parietal cortex.

Science.gov (United States)

Louie, Kenway; Grattan, Lauren E; Glimcher, Paul W

2011-07-20

The representation of value is a critical component of decision making. Rational choice theory assumes that options are assigned absolute values, independent of the value or existence of other alternatives. However, context-dependent choice behavior in both animals and humans violates this assumption, suggesting that biological decision processes rely on comparative evaluation. Here we show that neurons in the monkey lateral intraparietal cortex encode a relative form of saccadic value, explicitly dependent on the values of the other available alternatives. Analogous to extra-classical receptive field effects in visual cortex, this relative representation incorporates target values outside the response field and is observed in both stimulus-driven activity and baseline firing rates. This context-dependent modulation is precisely described by divisive normalization, indicating that this standard form of sensory gain control may be a general mechanism of cortical computation. Such normalization in decision circuits effectively implements an adaptive gain control for value coding and provides a possible mechanistic basis for behavioral context-dependent violations of rationality.

Classical approach in atomic physics

International Nuclear Information System (INIS)

Solov'ev, E.A.

2011-01-01

The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of a hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom discovered with the help of Poincare section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treated as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semiclassical series such as renormalization group symmetry, criterion of accuracy and so on are reviewed as well. (author)

Measuring receptive collocational competence across proficiency levels

Directory of Open Access Journals (Sweden)

Déogratias Nizonkiza

2015-12-01

Full Text Available The present study investigates, (i English as Foreign Language (EFL learners’ receptive collocational knowledge growth in relation to their linguistic proficiency level; (ii how much receptive collocational knowledge is acquired as proficiency develops; and (iii the extent to which receptive knowledge of collocations of EFL learners varies across word frequency bands. A proficiency measure and a collocation test were administered to English majors at the University of Burundi. Results of the study suggest that receptive collocational competence develops alongside EFL learners’ linguistic proficiency; which lends empirical support to Gyllstad (2007, 2009 and Author (2011 among others, who reported similar findings. Furthermore, EFL learners’ collocations growth seems to be quantifiable wherein both linguistic proficiency level and word frequency occupy a crucial role. While more gains in terms of collocations that EFL learners could potentially add as a result of change in proficiency are found at lower levels of proficiency; collocations of words from more frequent word bands seem to be mastered first, and more gains are found at more frequent word bands. These results confirm earlier findings on the non-linearity nature of vocabulary growth (cf. Meara 1996 and the fundamental role played by frequency in word knowledge for vocabulary in general (Nation 1983, 1990, Nation and Beglar 2007, which are extended here to collocations knowledge.

Developing Reception Competence in Children with a Mild Intellectual Disability

Directory of Open Access Journals (Sweden)

Ana Koritnik

2015-06-01

Full Text Available The paper presents research paradigms which study factors that allow influencing the language development of children with mild intellectual disabilities to the greatest extent possible. Special attention is dedicated to the development of the reception competence with the use of reception didactics methods based on a relatively frequent use of less demanding non-language semiotic functions. The core of the paper presents results of an experimental case study (on a sample of five children with a mild intellectual disability over a one school year period, through which the reception competence in these children was developed with a systematic use of an adapted communication model of literary education as an experimental factor. The results have confirmed the initially set hypothesis about reception progress.

Classical solutions and extended supergravity

International Nuclear Information System (INIS)

de Alfaro, V.; Fubini, S.; Furlan, G.

1980-03-01

The existence and properties of classical solutions for gravity coupled to matter fields have been investigated previously with the limitation to conformally flat solutions. In the search for a guiding criterion to determine the form of the coupling among the fields, one is led to consider supersymmetric theories, and the question arises whether classical solutions persist in these models. It is found that a discrepancy persists between supergravity and standard meron solutions. Owing to the appearance of the scalar field, a new set of meron solutions exists for particular Lagrangian models. In conclusion, the form of solutions in Minkowski space is discussed

Classical solutions in quantum field theory solitons and instantons in high energy physics

CERN Document Server

Weinberg, Erick J

2012-01-01

Classical solutions play an important role in quantum field theory, high energy physics and cosmology. Real-time soliton solutions give rise to particles, such as magnetic monopoles, and extended structures, such as domain walls and cosmic strings, that have implications for early universe cosmology. Imaginary-time Euclidean instantons are responsible for important nonperturbative effects, while Euclidean bounce solutions govern transitions between metastable states. Written for advanced graduate students and researchers in elementary particle physics, cosmology and related fields, this book brings the reader up to the level of current research in the field. The first half of the book discusses the most important classes of solitons: kinks, vortices and magnetic monopoles. The cosmological and observational constraints on these are covered, as are more formal aspects, including BPS solitons and their connection with supersymmetry. The second half is devoted to Euclidean solutions, with particular emphasis on ...

Random electrodynamics: the theory of classical electrodynamics with classical electromagnetic zero-point radiation

International Nuclear Information System (INIS)

Boyer, T.H.

1975-01-01

The theory of classical electrodynamics with classical electromagnetic zero-point radiation is outlined here under the title random electrodynamics. The work represents a reanalysis of the bounds of validity of classical electron theory which should sharpen the understanding of the connections and distinctions between classical and quantum theories. The new theory of random electrodynamics is a classical electron theory involving Newton's equations for particle motion due to the Lorentz force, and Maxwell's equations for the electromagnetic fields with point particles as sources. However, the theory departs from the classical electron theory of Lorentz in that it adopts a new boundary condition on Maxwell's equations. It is assumed that the homogeneous boundary condition involves random classical electromagnetic radiation with a Lorentz-invariant spectrum, classical electromagnetic zero-point radiation. The implications of random electrodynamics for atomic structure, atomic spectra, and particle-interference effects are discussed on an order-of-magnitude or heuristic level. Some detailed mathematical connections and some merely heuristic connections are noted between random electrodynamics and quantum theory. (U.S.)

Gauge bridges in classical field theory; Eichbruecken in der klassischen Feldtheorie

Energy Technology Data Exchange (ETDEWEB)

Jakobs, S.

2009-03-15

In this thesis Poisson structures of two classical gauge field theories (Maxwell-Klein-Gordon- and Maxwell-Dirac-system) are constructed using the parametrix construction of Green's functions. Parametrices for the Maxwell-Klein-Gordon- and Maxwell-Dirac-system are constructed in Minkowski space and this construction is later generalized to curved space times for the Maxwell-Klein-Gordon-system. With these Green's functions Poisson brackets will be defined as Peierls brackets. Finally non-local, gauge invariant observables, the so-called 'gauge bridges'are constructed. Gauge bridges are the matrix elements of holonomy operators. It is shown, that these emerge from Poisson brackets of local, gauge invariant observables. (orig.)

The Early Literary Reception of Ernest Hemingway in Iran

Directory of Open Access Journals (Sweden)

Atefeh Ghasemnejad

2018-01-01

Full Text Available This essay investigates the dynamics that led to the literary reception of Ernest Hemingway before the Islamic Revolution in Iran. This article deploys reception studies as a branch of Comparative Literature with a focus upon conceptions of Siegbert Salomon Prawer and the practical method of George Asselineau to unearth the ideological, political, and historical milieu that embraced Hemingway’s literary fortune in Iran. This investigation, unprecedented in the study of Iranian literature, discusses how and why Hemingway was initially received in Iran. As such, the inception of literary fortune of Ernest Hemingway in Iran is examined by the contextual features, Persian literary taste, and the translator’s incentives that paved the way for this reception. This article also uncovers the reasons for the delay in the literary reception of Hemingway in Iran and discussed why some of Hemingway’s oeuvres enjoyed recognition while others were neglected by the Iranian readership.

Expressive and receptive language skills in preschool children from a socially disadvantaged area.

Science.gov (United States)

Ryan, Ashling; Gibbon, Fiona E; O'shea, Aoife

2016-02-01

Evidence suggests that children present with receptive language skills that are equivalent to or more advanced than expressive language skills. This profile holds true for typical and delayed language development. This study aimed to determine if such a profile existed for preschool children from an area of social deprivation and to investigate if particular language skills influence any differences found between expressive and receptive skills. Data from 187 CELF P2 UK assessments conducted on preschool children from two socially disadvantaged areas in a city in southern Ireland. A significant difference was found between Receptive Language Index (RLI) and Expressive Language Index (ELI) scores with Receptive scores found to be lower than Expressive scores. The majority (78.6%) of participants had a lower Receptive Language than Expressive score (RLI ELI), with very few (3.2%) having the same Receptive and Expressive scores (RLI = ELI). Scores for the Concepts and Following Directions (receptive) sub-test were significantly lower than for the other receptive sub tests, while scores for the Expressive Vocabulary sub-test were significantly higher than for the other expressive sub tests. The finding of more advanced expressive than receptive language skills in socially deprived preschool children is previously unreported and clinically relevant for speech-language pathologists in identifying the needs of this population.

Classical dynamics and localization of resonances in the high-energy region of the hydrogen atom in crossed fields.

Science.gov (United States)

Schweiner, Frank; Main, Jörg; Cartarius, Holger; Wunner, Günter

2015-01-01

When superimposing the potentials of external fields on the Coulomb potential of the hydrogen atom, a saddle point (called the Stark saddle point) appears. For energies slightly above the saddle point energy, one can find classical orbits that are located in the vicinity of this point. We follow those so-called quasi-Penning orbits to high energies and field strengths, observing structural changes and uncovering their bifurcation behavior. By plotting the stability behavior of those orbits against energy and field strength, the appearance of a stability apex is reported. A cusp bifurcation, located in the vicinity of the apex, will be investigated in detail. In this cusp bifurcation, another orbit of similar shape is found. This orbit becomes completely stable in the observed region of positive energy, i.e., in a region of parameter space, where the Kepler-like orbits located around the nucleus are already unstable. By quantum mechanically exact calculations, we prove the existence of signatures in quantum spectra belonging to those orbits. Husimi distributions are used to compare quantum-Poincaré sections with the extension of the classical torus structure around the orbits. Since periodic orbit theory predicts that each classical periodic orbit contributes an oscillating term to photoabsorption spectra, we finally give an estimation for future experiments, which could verify the existence of the stable orbits.

Inhomogeneous compact extra dimensions

Energy Technology Data Exchange (ETDEWEB)

Bronnikov, K.A. [Center of Gravity and Fundamental Metrology, VNIIMS, 46 Ozyornaya st., Moscow 119361 (Russian Federation); Budaev, R.I.; Grobov, A.V.; Dmitriev, A.E.; Rubin, Sergey G., E-mail: kb20@yandex.ru, E-mail: buday48@mail.ru, E-mail: alexey.grobov@gmail.com, E-mail: alexdintras@mail.ru, E-mail: sergeirubin@list.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409 Moscow (Russian Federation)

2017-10-01

We show that an inhomogeneous compact extra space possesses two necessary features— their existence does not contradict the observable value of the cosmological constant Λ{sub 4} in pure f ( R ) theory, and the extra dimensions are stable relative to the 'radion mode' of perturbations, the only mode considered. For a two-dimensional extra space, both analytical and numerical solutions for the metric are found, able to provide a zero or arbitrarily small Λ{sub 4}. A no-go theorem has also been proved, that maximally symmetric compact extra spaces are inconsistent with 4D Minkowski space in the framework of pure f ( R ) gravity.

Case study in Venezuela : performance of multiphase meter in extra heavy oil

Energy Technology Data Exchange (ETDEWEB)

Marin, A. [Petroleos de Venezuela SA, Caracas (Venezuela); Bornia, O.; Pinguet, B. [Schlumberger Canada Ltd., Edmonton, AB (Canada)

2008-10-15

The performance of a multiphase meter that combines Venturi and multi energy gamma rays was investigated during operation in an extra heavy oil field in Venezuela. The Orocual field in Monagas is one of the most diverse oilfields in Venezuela. It produces gas condensate, light and medium oil and has recently started to produce from a heavy and extra-heavy oil reservoir, with a gravity between 8.6 and 11 API and a viscosity range from 6 Pa.s to more than 20 Pa.s at line conditions. Petroleos de Venezuela SA (PDVSA) is currently using cold production systems in this field. PDVSA attempted to estimate the liquid flow rate using conventional storage tanks but was unable to evaluate the gas production in such an environment of low GOR with emulsion, large amounts of foam and high viscosity. Since the density of heavy oil is close to the density of water, gravity separation cannot be applied. Also, since heavy oil is very viscous, proper separation requires a long retention time, which is not feasible in terms of space or economy. In addition, gas bubbles could not flow freely and remained as a gas phase trapped inside the liquid, resulting in an overestimation of some of the liquid flow rate. In order to measure the field's oil, water and gas flow rates, PDVSA tried several multiphase meters but found that a Venturi and multi energy gamma ray combination was the only solution able to accurately measure multiphase flow in its extra heavy oil. A test demonstrated that, compared to a tank system, the overall uncertainty of the Venturi combination was better than 2 per cent. This extended the operating envelope for PDVSA for using this multiphase metering technology, providing the capability to monitor and optimize in real-time the production in this extra heavy oil field. 15 refs., 10 figs.

Learning Peri-saccadic Remapping of Receptive Field from Experience in Lateral Intraparietal Area.

Science.gov (United States)

Wang, Xiao; Wu, Yan; Zhang, Mingsha; Wu, Si

2017-01-01

Our eyes move constantly at a frequency of 3-5 times per second. These movements, called saccades, induce the sweeping of visual images on the retina, yet we perceive the world as stable. It has been suggested that the brain achieves this visual stability via predictive remapping of neuronal receptive field (RF). A recent experimental study disclosed details of this remapping process in the lateral intraparietal area (LIP), that is, about the time of the saccade, the neuronal RF expands along the saccadic trajectory temporally, covering the current RF (CRF), the future RF (FRF), and the region the eye will sweep through during the saccade. A cortical wave (CW) model was also proposed, which attributes the RF remapping as a consequence of neural activity propagating in the cortex, triggered jointly by a visual stimulus and the corollary discharge (CD) signal responsible for the saccade. In this study, we investigate how this CW model is learned naturally from visual experiences at the development of the brain. We build a two-layer network, with one layer consisting of LIP neurons and the other superior colliculus (SC) neurons. Initially, neuronal connections are random and non-selective. A saccade will cause a static visual image to sweep through the retina passively, creating the effect of the visual stimulus moving in the opposite direction of the saccade. According to the spiking-time-dependent-plasticity rule, the connection path in the opposite direction of the saccade between LIP neurons and the connection path from SC to LIP are enhanced. Over many such visual experiences, the CW model is developed, which generates the peri-saccadic RF remapping in LIP as observed in the experiment.

Quantum and classical behavior in interacting bosonic systems

Energy Technology Data Exchange (ETDEWEB)

Hertzberg, Mark P. [Institute of Cosmology & Department of Physics and Astronomy, Tufts University,Medford, MA 02155 (United States)

2016-11-21

It is understood that in free bosonic theories, the classical field theory accurately describes the full quantum theory when the occupancy numbers of systems are very large. However, the situation is less understood in interacting theories, especially on time scales longer than the dynamical relaxation time. Recently there have been claims that the quantum theory deviates spectacularly from the classical theory on this time scale, even if the occupancy numbers are extremely large. Furthermore, it is claimed that the quantum theory quickly thermalizes while the classical theory does not. The evidence for these claims comes from noticing a spectacular difference in the time evolution of expectation values of quantum operators compared to the classical micro-state evolution. If true, this would have dramatic consequences for many important phenomena, including laboratory studies of interacting BECs, dark matter axions, preheating after inflation, etc. In this work we critically examine these claims. We show that in fact the classical theory can describe the quantum behavior in the high occupancy regime, even when interactions are large. The connection is that the expectation values of quantum operators in a single quantum micro-state are approximated by a corresponding classical ensemble average over many classical micro-states. Furthermore, by the ergodic theorem, a classical ensemble average of local fields with statistical translation invariance is the spatial average of a single micro-state. So the correlation functions of the quantum and classical field theories of a single micro-state approximately agree at high occupancy, even in interacting systems. Furthermore, both quantum and classical field theories can thermalize, when appropriate coarse graining is introduced, with the classical case requiring a cutoff on low occupancy UV modes. We discuss applications of our results.

Field-testing of the ICHD-3 beta diagnostic criteria for classical trigeminal neuralgia

DEFF Research Database (Denmark)

Maarbjerg, Stine; Sørensen, Morten Togo; Gozalov, Aydin

2015-01-01

INTRODUCTION: We aimed to field-test the beta version of the third edition of the International Classification of Headache Disorders (ICHD-3 beta) diagnostic criteria for classical trigeminal neuralgia (TN). The proposed beta draft of the 11th version of the International Classification of Diseases...... (ICD-11 beta) is almost exclusively based on the ICHD-3 beta classification structure although slightly abbreviated. We compared sensitivity and specificity to ICHD-2 criteria, and evaluated the needs for revision. METHODS: Clinical characteristics were systematically and prospectively collected from...

The time dependent Schrodinger equation revisited I: quantum field and classical Hamilton-Jacobi routes to Schrodinger's wave equation

International Nuclear Information System (INIS)

Scully, M O

2008-01-01

The time dependent Schrodinger equation is frequently 'derived' by postulating the energy E → i h-bar (∂/∂t) and momentum p-vector → ( h-bar /i)∇ operator relations. In the present paper we review the quantum field theoretic route to the Schrodinger wave equation which treats time and space as parameters, not operators. Furthermore, we recall that a classical (nonlinear) wave equation can be derived from the classical action via Hamiltonian-Jacobi theory. By requiring the wave equation to be linear we again arrive at the Schrodinger equation, without postulating operator relations. The underlying philosophy is operational: namely 'a particle is what a particle detector detects.' This leads us to a useful physical picture combining the wave (field) and particle paradigms which points the way to the time-dependent Schrodinger equation

Extra dimensions hypothesis in high energy physics

Directory of Open Access Journals (Sweden)

Volobuev Igor

2017-01-01

Full Text Available We discuss the history of the extra dimensions hypothesis and the physics and phenomenology of models with large extra dimensions with an emphasis on the Randall- Sundrum (RS model with two branes. We argue that the Standard Model extension based on the RS model with two branes is phenomenologically acceptable only if the inter-brane distance is stabilized. Within such an extension of the Standard Model, we study the influence of the infinite Kaluza-Klein (KK towers of the bulk fields on collider processes. In particular, we discuss the modification of the scalar sector of the theory, the Higgs-radion mixing due to the coupling of the Higgs boson to the radion and its KK tower, and the experimental restrictions on the mass of the radion-dominated states.

An application of information theory to stochastic classical gravitational fields

Science.gov (United States)

Angulo, J.; Angulo, J. C.; Angulo, J. M.

2018-06-01

The objective of this study lies on the incorporation of the concepts developed in the Information Theory (entropy, complexity, etc.) with the aim of quantifying the variation of the uncertainty associated with a stochastic physical system resident in a spatiotemporal region. As an example of application, a relativistic classical gravitational field has been considered, with a stochastic behavior resulting from the effect induced by one or several external perturbation sources. One of the key concepts of the study is the covariance kernel between two points within the chosen region. Using this concept and the appropriate criteria, a methodology is proposed to evaluate the change of uncertainty at a given spatiotemporal point, based on available information and efficiently applying the diverse methods that Information Theory provides. For illustration, a stochastic version of the Einstein equation with an added Gaussian Langevin term is analyzed.

Pseudoclassical fermionic model and classical solutions

International Nuclear Information System (INIS)

Smailagic, A.

1981-08-01

We study classical limit of fermionic fields seen as Grassmann variables and deduce the proper quantization prescription using Dirac's method for constrained systems and investigate quantum meaning of classical solutions for the Thirring model. (author)

Performance of extended Lagrangian schemes for molecular dynamics simulations with classical polarizable force fields and density functional theory.

Science.gov (United States)

Vitale, Valerio; Dziedzic, Jacek; Albaugh, Alex; Niklasson, Anders M N; Head-Gordon, Teresa; Skylaris, Chris-Kriton

2017-03-28

Iterative energy minimization with the aim of achieving self-consistency is a common feature of Born-Oppenheimer molecular dynamics (BOMD) and classical molecular dynamics with polarizable force fields. In the former, the electronic degrees of freedom are optimized, while the latter often involves an iterative determination of induced point dipoles. The computational effort of the self-consistency procedure can be reduced by re-using converged solutions from previous time steps. However, this must be done carefully, as not to break time-reversal symmetry, which negatively impacts energy conservation. Self-consistent schemes based on the extended Lagrangian formalism, where the initial guesses for the optimized quantities are treated as auxiliary degrees of freedom, constitute one elegant solution. We report on the performance of two integration schemes with the same underlying extended Lagrangian structure, which we both employ in two radically distinct regimes-in classical molecular dynamics simulations with the AMOEBA polarizable force field and in BOMD simulations with the Onetep linear-scaling density functional theory (LS-DFT) approach. Both integration schemes are found to offer significant improvements over the standard (unpropagated) molecular dynamics formulation in both the classical and LS-DFT regimes.

EXTRA LIFE

Directory of Open Access Journals (Sweden)

Ruth S. Contreras Espinosa

2016-02-01

Full Text Available El creciente número de personas jugando videojuegos significa que estos están teniendo un efecto innegable sobre nuestra cultura. Este efecto es claramente visible en una aceptación general. Los videojuegos también han cambiado la forma en que muchas otras formas de medios de comunicación, se producen y consumen. Los videojuegos tienen una influencia creciente en nuestra cultura, y en "EXTRA LIFE" diferentes autores expresan sus opiniones sobre este nuevo medio. EXTRA LIFE Abstract The increasing number of people playing video games means that they are having an undeniable effect on culture. This effect is clearly visible in the increasing mainstream acceptance of aspects of gaming culture. Video games have also changed the way that many other forms of media, are produced and consumed. Video games have an increasing influence on our culture,  and in "EXTRA LIFE" diferent authors have voiced their opinions on this new media. Keywords: Video games; culture; effects; games.

Receptivity of Hypersonic Boundary Layers to Acoustic and Vortical Disturbances (Invited)

Science.gov (United States)

Balakumar, P.

2015-01-01

Boundary-layer receptivity to two-dimensional acoustic and vortical disturbances for hypersonic flows over two-dimensional and axi-symmetric geometries were numerically investigated. The role of bluntness, wall cooling, and pressure gradients on the receptivity and stability were analyzed and compared with the sharp nose cases. It was found that for flows over sharp nose geometries in adiabatic wall conditions the instability waves are generated in the leading-edge region and that the boundary layer is much more receptive to slow acoustic waves as compared to the fast waves. The computations confirmed the stabilizing effect of nose bluntness and the role of the entropy layer in the delay of boundary layer transition. The receptivity coefficients in flows over blunt bodies are orders of magnitude smaller than that for the sharp cone cases. Wall cooling stabilizes the first mode strongly and destabilizes the second mode. However, the receptivity coefficients are also much smaller compared to the adiabatic case. The adverse pressure gradients increased the unstable second mode regions.

Lagrangian formulation of classical BMT-theory

International Nuclear Information System (INIS)

Pupasov-Maksimov, Andrey; Deriglazov, Alexei; Guzman, Walberto

2013-01-01

Full text: The most popular classical theory of electron has been formulated by Bargmann, Michel and Telegdi (BMT) in 1959. The BMT equations give classical relativistic description of a charged particle with spin and anomalous magnetic momentum moving in homogeneous electro-magnetic field. This allows to study spin dynamics of polarized beams in uniform fields. In particular, first experimental measurements of muon anomalous magnetic momentum were done using changing of helicity predicted by BMT equations. Surprisingly enough, a systematic formulation and the analysis of the BMT theory are absent in literature. In the present work we particularly fill this gap by deducing Lagrangian formulation (variational problem) for BMT equations. Various equivalent forms of Lagrangian will be discussed in details. An advantage of the obtained classical model is that the Lagrangian action describes a relativistic spinning particle without Grassmann variables, for both free and interacting cases. This implies also the possibility of canonical quantization. In the interacting case, an arbitrary electromagnetic background may be considered, which generalizes the BMT theory formulated to the case of homogeneous fields. The classical model has two local symmetries, which gives an interesting example of constrained classical dynamics. It is surprising, that the case of vanishing anomalous part of the magnetic momentum is naturally highlighted in our construction. (author)

Extra-electron induced covalent strengthening and generalization of intrinsic ductile-to-brittle criterion.

Science.gov (United States)

Niu, Haiyang; Chen, Xing-Qiu; Liu, Peitao; Xing, Weiwei; Cheng, Xiyue; Li, Dianzhong; Li, Yiyi

2012-01-01

Traditional strengthening ways, such as strain, precipitation, and solid-solution, come into effect by pinning the motion of dislocation. Here, through first-principles calculations we report on an extra-electron induced covalent strengthening mechanism, which alters chemical bonding upon the introduction of extra-valence electrons in the matrix of parent materials. It is responsible for the brittle and high-strength properties of Al(12)W-type compounds featured by the typical fivefold icosahedral cages, which are common for quasicrystals and bulk metallic glasses (BMGs). In combination with this mechanism, we generalize ductile-to-brittle criterion in a universal hyperbolic form by integrating the classical Pettifor's Cauchy pressure with Pugh's modulus ratio for a wide variety of materials with cubic lattices. This study provides compelling evidence to correlate Pugh's modulus ratio with hardness of materials and may have implication for understanding the intrinsic brittleness of quasicrystals and BMGs.

Health Challenges in Refugee Reception: Dateline Europe 2016.

Science.gov (United States)

Blitz, Brad K; d'Angelo, Alessio; Kofman, Eleonore; Montagna, Nicola

2017-11-30

The arrival of more than one million migrants, many of them refugees, has proved a major test for the European Union. Although international relief and monitoring agencies have been critical of makeshift camps in Calais and Eidomeni where infectious disease and overcrowding present major health risks, few have examined the nature of the official reception system and its impact on health delivery. Drawing upon research findings from an Economic and Social Research Council (ESRC) funded project, this article considers the physical and mental health of asylum-seekers in transit and analyses how the closure of borders has engendered health risks for populations in recognised reception centres in Sicily and in Greece. Data gathered by means of a survey administered in Greece (300) and in Sicily (400), and complemented by in-depth interviews with migrants (45) and key informants (50) including representatives of government offices, humanitarian and relief agencies, NGOs and activist organisations, are presented to offer an analysis of the reception systems in the two frontline states. We note that medical provision varies significantly from one centre to another and that centre managers play a critical role in the transmission of vital information. A key finding is that, given such disparity, the criteria used by the UNHCR to grade health services reception do not address the substantive issue that prevent refugees from accessing health services, even when provided on site. Health provision is not as recorded in UNHCR reporting but rather there are critical gaps between provision, awareness, and access for refugees in reception systems in Sicily and in Greece. This article concludes that there is a great need for more information campaigns to direct refugees to essential services.

Predicting Receptive-Expressive Vocabulary Discrepancies in Preschool Children With Autism Spectrum Disorder.

Science.gov (United States)

McDaniel, Jena; Yoder, Paul; Woynaroski, Tiffany; Watson, Linda R

2018-05-15

Correlates of receptive-expressive vocabulary size discrepancies may provide insights into why language development in children with autism spectrum disorder (ASD) deviates from typical language development and ultimately improve intervention outcomes. We indexed receptive-expressive vocabulary size discrepancies of 65 initially preverbal children with ASD (20-48 months) to a comparison sample from the MacArthur-Bates Communicative Development Inventories Wordbank (Frank, Braginsky, Yurovsky, & Marchman, 2017) to quantify typicality. We then tested whether attention toward a speaker and oral motor performance predict typicality of the discrepancy 8 months later. Attention toward a speaker correlated positively with receptive-expressive vocabulary size discrepancy typicality. Imitative and nonimitative oral motor performance were not significant predictors of vocabulary size discrepancy typicality. Secondary analyses indicated that midpoint receptive vocabulary size mediated the association between initial attention toward a speaker and end point receptive-expressive vocabulary size discrepancy typicality. Findings support the hypothesis that variation in attention toward a speaker might partially explain receptive-expressive vocabulary size discrepancy magnitude in children with ASD. Results are consistent with an input-processing deficit explanation of language impairment in this clinical population. Future studies should test whether attention toward a speaker is malleable and causally related to receptive-expressive discrepancies in children with ASD.

Mathematical physics classical mechanics

CERN Document Server

Knauf, Andreas

2018-01-01

As a limit theory of quantum mechanics, classical dynamics comprises a large variety of phenomena, from computable (integrable) to chaotic (mixing) behavior. This book presents the KAM (Kolmogorov-Arnold-Moser) theory and asymptotic completeness in classical scattering. Including a wealth of fascinating examples in physics, it offers not only an excellent selection of basic topics, but also an introduction to a number of current areas of research in the field of classical mechanics. Thanks to the didactic structure and concise appendices, the presentation is self-contained and requires only knowledge of the basic courses in mathematics. The book addresses the needs of graduate and senior undergraduate students in mathematics and physics, and of researchers interested in approaching classical mechanics from a modern point of view.

[The classical parasite: from appreciative partners of the gods to serving as jesters].

Science.gov (United States)

Hassl, Andreas

2005-01-01

A [pialpharhoalphasigmaiotatauomicronzeta] = parasitos = parasite of the classical Greek antiquity was a tolerated, but not invited co-eater during a guest meal. Usually a parasite was an illegitimate, incapable to inherit or anyway pauperised, free, young man who had to pay for his meal with exhilaration of the guests, adulation, maintenance art, and humiliation. However, during the more than two millennia lasting development of the classical antique society, even this little prestigious profession was preceded by a stupendous development, reflecting an unprecedented devaluation of this socially enforced activity. At the outset of the development there stood the archaic, neolithic social order of Greece, within which a parasitos was the selected partner of the divinity and at the same time a civil servant of a municipality and an outstanding citizen of a community. In the classical antiquity the term parasitos had a socio-political contents above all; the term incorporated itself into the ancient sacral, social, and constitutional spheres. The transformation to a medical word meaning took originally place in the course of an erroneous reception during the 17th century.

Extra Facial Landmark Localization via Global Shape Reconstruction

Directory of Open Access Journals (Sweden)

Shuqiu Tan

2017-01-01

Full Text Available Localizing facial landmarks is a popular topic in the field of face analysis. However, problems arose in practical applications such as handling pose variations and partial occlusions while maintaining moderate training model size and computational efficiency still challenges current solutions. In this paper, we present a global shape reconstruction method for locating extra facial landmarks comparing to facial landmarks used in the training phase. In the proposed method, the reduced configuration of facial landmarks is first decomposed into corresponding sparse coefficients. Then explicit face shape correlations are exploited to regress between sparse coefficients of different facial landmark configurations. Finally extra facial landmarks are reconstructed by combining the pretrained shape dictionary and the approximation of sparse coefficients. By applying the proposed method, both the training time and the model size of a class of methods which stack local evidences as an appearance descriptor can be scaled down with only a minor compromise in detection accuracy. Extensive experiments prove that the proposed method is feasible and is able to reconstruct extra facial landmarks even under very asymmetrical face poses.

Supersymmetry Breaking through Transparent Extra Dimensions

Energy Technology Data Exchange (ETDEWEB)

Schmaltz, Martin

1999-11-23

We propose a new framework for mediating supersymmetry breaking through an extra dimension. It predicts positive scalar masses and solves the supersymmetric flavor problem. Supersymmetry breaks on a ''source'' brane that is spatially separated from a parallel brane on which the standard model matter fields and their superpartners live. The gauge and gaugino fields propagate in the bulk, the latter receiving a supersymmetry breaking mass from direct couplings to the source brane. Scalar masses are suppressed at the high scale but are generated via the renormalization group. We briefly discuss the spectrum and collider signals for a range of compactification scales.

Magnetic and electric dipole constraints on extra dimensions and magnetic fluxes

International Nuclear Information System (INIS)

Roy, Aaron J.; Bander, Myron

2009-01-01

The propagation of charged particles and gauge fields in a compact extra dimension contributes to g-2 of the charged particles. In addition, a magnetic flux threading this extra dimension generates an electric dipole moment for these particles. We present constraints on the compactification size and on the possible magnetic flux imposed by the comparison of data and theory of the magnetic moment of the muon and from limits on the electric dipole moments of the muon, neutron and electron

Classical region of a trapped Bose gas

Energy Technology Data Exchange (ETDEWEB)

Blakie, P Blair [Jack Dodd Centre for Photonics and Ultra-Cold Atoms, University of Otago, Dunedin (New Zealand); Davis, Matthew J [ARC Centre of Excellence for Quantum-Atom Optics, School of Physical Sciences, University of Queensland, Brisbane, QLD 4072 (Australia)

2007-06-14

The classical region of a Bose gas consists of all single particle modes that have a high average occupation and are well described by a classical field. Highly occupied modes only occur in massive Bose gases at ultra-cold temperatures, in contrast to the photon case where there are highly occupied modes at all temperatures. For the Bose gas the number of these modes is dependent on the temperature, the total number of particles and their interaction strength. In this paper, we characterize the classical region of a harmonically trapped Bose gas over a wide parameter regime. We use a Hartree-Fock approach to account for the effects of interactions, which we observe to significantly change the classical region as compared to the idealized case. We compare our results to full classical field calculations and show that the Hartree-Fock approach provides a qualitatively accurate description of a classical region for the interacting gas.

First-year university students’ receptive and productive use of academic vocabulary

Directory of Open Access Journals (Sweden)

Déogratias Nizonkiza

2016-05-01

Full Text Available The present study explores academic vocabulary knowledge, operationalised through the Academic Word List, among first-year higher education students. Both receptive and productive knowledge and the proportion between the two are examined. Results show that while receptive knowledge is readily acquired by first-year students, productive knowledge lags behind and remains problematic. This entails that receptive knowledge is much larger than productive knowledge, which confirms earlier indications that receptive vocabulary knowledge is larger than productive knowledge for both academic vocabulary (Zhou 2010 and general vocabulary (cf. Laufer 1998, Webb 2008, among others. Furthermore, results reveal that the ratio between receptive and productive knowledge is slightly above 50%, which lends empirical support to previous findings that the ratio between the two aspects of vocabulary knowledge can be anywhere between 50% and 80% (Milton 2009. This finding is extended here to academic vocabulary; complementing Zhou’s (2010 study that investigated the relationship between the two aspects of vocabulary knowledge without examining the ratio between them. On the basis of these results, approaches that could potentially contribute to fostering productive knowledge growth are discussed. Avenues worth exploring to gain further insight into the relationship between receptive and productive knowledge are also suggested.

Searches for dark matter and extra dimensions with the ATLAS detector

CERN Document Server

Clement, C; The ATLAS collaboration

2014-01-01

This paper presents the results of different approaches to finding evidence for dark matter with the ATLAS experiment at LHC. These include searches for events with large missing transverse momentum and a single jet, photon or W/Z boson. Searches for hidden sectors in events with long-lived particles resulting in displaced hadronic vertices or lepton-jet signatures are also reported. Finally, studies sensitive to the presence of extra spatial dimensions are described, as for example classical and quantum black holes and other non-resonant phenomena. Results from s = 8 TeV ATLAS data taking are presented.

Higgs bosons in extra dimensions

Science.gov (United States)

Quiros, Mariano

2015-05-01

In this paper, motivated by the recent discovery of a Higgs-like boson at the Large Hadron Collider (LHC) with a mass mH≃125 GeV, we review different models where the hierarchy problem is solved by means of a warped extra dimension. In the Randall-Sundrum (RS) model electroweak observables provide very strong bounds on the mass of KK modes which motivates extensions to overcome this problem. Two extensions are briefly discussed. One particular extension is based on the deformation of the metric such that it strongly departs from the AdS5 structure in the IR region while it goes asymptotically to AdS5 in the UV brane. This model has the IR brane close to a naked metric singularity (which is outside the physical interval) characteristic of soft-walls constructions. The proximity of the singularity provides a strong wave function renormalization for the Higgs field which suppresses the T and S parameters. The second class of considered extensions are based on the introduction of an extra gauge group in the bulk such that the custodial SU(2)R symmetry is gauged and protects the T parameter. By further enlarging the bulk gauge symmetry one can find models where the Higgs is identified with the fifth component of gauge fields and for which the Higgs potential along with the Higgs mass can be dynamically determined by the Coleman-Weinberg mechanism.

Method of optical coherence tomography with parallel depth-resolved signal reception and fibre-optic phase modulators

Energy Technology Data Exchange (ETDEWEB)

Morozov, A N; Turchin, I V [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2013-12-31

The method of optical coherence tomography with the scheme of parallel reception of the interference signal (P-OCT) is developed on the basis of spatial paralleling of the reference wave by means of a phase diffraction grating producing the appropriate time delay in the Mach–Zehnder interferometer. The absence of mechanical variation of the optical path difference in the interferometer essentially reduces the time required for 2D imaging of the object internal structure, as compared to the classical OCT that uses the time-domain method of the image construction, the sensitivity and the dynamic range being comparable in both approaches. For the resulting field of the interfering object and reference waves an analytical expression is derived that allows the calculation of the autocorrelation function in the plane of photodetectors. For the first time a method of linear phase modulation by 2π is proposed for P-OCT systems, which allows the use of compact high-frequency (a few hundred kHz) piezoelectric cell-based modulators. For the demonstration of the P-OCT method an experimental setup was created, using which the images of the inner structure of biological objects at the depth up to 1 mm with the axial spatial resolution of 12 μm were obtained. (optical coherence tomography)

Effects of a conducting E layer on classical F region cross-field plasma diffusion

International Nuclear Information System (INIS)

Vickrey, J.F.; Kelley, M.C.

1982-01-01

The rate of cross-field plasma diffusion in the F region ionosphere is significantly increased when the magnetic field lines thread a highly conducting E region below. This reduces the lifetime of small-scale F region electron density irregularities in the polar ionosphere where the presence of a highly conducting E region is comonplace. A simple mmodel is developed to describe the effects of a conducting E layer on classical F region plasma diffusion. In the absence of an E region, the difference in ion and electron diffusion rates leads to a charge separation and, hence, to an electrostatic field that retards ion diffusion. When the highly conducting magnetic field lines are tied to a conducting E region, however, electrons can flow along B to reduce the ambipolar diffusion electric field, and ions can proceed perpendicular to B at a rate approaching their own (higher) diffusion velocity. It is shown that the enhanced total diffusion rate that results depends strongly on the height of the F layer and on the ratio of the E to F region Pedersen conductivities

Non-Gaussian statistics, classical field theory, and realizable Langevin models

International Nuclear Information System (INIS)

Krommes, J.A.

1995-11-01

The direct-interaction approximation (DIA) to the fourth-order statistic Z ∼ left-angle λψ 2 ) 2 right-angle, where λ is a specified operator and ψ is a random field, is discussed from several points of view distinct from that of Chen et al. [Phys. Fluids A 1, 1844 (1989)]. It is shown that the formula for Z DIA already appeared in the seminal work of Martin, Siggia, and Rose (Phys. Rev. A 8, 423 (1973)] on the functional approach to classical statistical dynamics. It does not follow from the original generalized Langevin equation (GLE) of Leith [J. Atmos. Sd. 28, 145 (1971)] and Kraichnan [J. Fluid Mech. 41, 189 (1970)] (frequently described as an amplitude representation for the DIA), in which the random forcing is realized by a particular superposition of products of random variables. The relationship of that GLE to renormalized field theories with non-Gaussian corrections (''spurious vertices'') is described. It is shown how to derive an improved representation, that realizes cumulants through O(ψ 4 ), by adding to the GLE a particular non-Gaussian correction. A Markovian approximation Z DIA M to Z DIA is derived. Both Z DIA and Z DIA M incorrectly predict a Gaussian kurtosis for the steady state of a solvable three-mode example

Classical particles with spin in electromagnetic and gravitational fields

International Nuclear Information System (INIS)

Amorim, R.M. de.

1977-02-01

Following a review of several problems connected with classical particles with intrinsic angular momentum are reproduced the Frenkel equations (with the condition S sup(μν)U sub(ν)=0) by means of a holonomic variational principle, and have related them to Bargann, Michel and Tededgie equations. The treatment is then generalized to the case in wich S sup(μν)U sub(ν)=0 and the resulting equation coincide in the linearized limit with those obtained by Suttorp and de Groot. Also, by using variational principles, the generalizations to Frenkel equations are obtained, as well as to those of Suttorp and de Groot when electromagnetic and gravitational interactions are considered. Finally, those equations are analysed according to a scheme proposed by Oliveira and Tiommo where the gravitational interactions are described by gravielectric and gravimagnetic fields. The analogies in these equations of motion between the gravitational and eletromagnetic interactions, in the case in which the particle has a giromagnetic factor g=1, are shown. The last results complete a previous study by wald. (Author) [pt

Diagnosis of intestinal and extra intestinal amoebiasis

International Nuclear Information System (INIS)

Lopez, Myriam Consuelo; Quiroz, Damian Arnoldo; Pinilla, Analida Elizabeth

2007-01-01

The objective is to carry out a review of the national and international literature as of the XXth century in order to update the advances for the diagnosis of complex odd Entamoeba histolytic / Entamoeba dispar and that of intestinal and extra intestinal amoebiasis that may be of use to the scientific community. As well as to unify the diagnostic criteria of this parasitosis known as a public health problem, and as a consequence of that, optimize the quality of population care. Data source: there was a systematic search for the scientific literature Publisher in Spanish and English since 1960 until today, this selection started on the first semester of 2006 until 2007, in the development of the line on intestinal and extra-intestinal amoebiasis of the Medical School of the National University of Colombia. A retrospective search process was carried out, systematically reviewing the most relevant articles as well as the products of this research line. In deciding how to make this article, there was a continuous search in different data bases such as Medline, SciELO and other bases in the library of the National University of Colombia, as well as other classical books related to the subject. For that purpose the terms amoebiasis, odd Entamoeba histolytic, Entamoeba, diagnosis, epidemiology, dysentery, amoebic liver abscess, were used. Studies selection: titles and abstracts were reviewed to select the original publications and the most representative ones related to this article's subject. Data extraction: the articles were classified according to the subject, the chronology and the authors according to the scientific contribution to solve the problem. Synthesis of the data: in the fi rst instance, a chronological critical analysis was carried out to order and synthesize the progress made in the diagnosis until confirmation of the experts' agreements in the field of amoebiasis was obtained throughout the world. Conclusion: this article summarizes what has taken place

Vortex currents in turbulent superfluid and classical fluid channel flow, the magnus effect, and Goldstone boson fields

International Nuclear Information System (INIS)

Huggins, E.R.

1994-01-01

Expressing hydrodynamics in terms of the flow of vorticity, using the vortex current tensor, helps unify the picture of turbulent channel flow for viscous fluids and for superfluids. In both, eddy viscosity plays a major role in energy dissipation, and in both there is a similar cross stream flow of vorticity, which in the case of superfluids leads to the Josephson frequency. The vortex current tensor, which was introduced in an earlier paper to derive an exact three dimensional Magnus effect formula, turns out to be the classical hydrodynamic limit of the vortex current that is the source for a classical Goldstone-boson field

A Classical Based Derivation of Time Dilation Providing First Order Accuracy to Schwarzschild's Solution of Einstein's Field Equations

Science.gov (United States)

Austin, Rickey W.

In Einstein's theory of Special Relativity (SR), one method to derive relativistic kinetic energy is via applying the classical work-energy theorem to relativistic momentum. This approach starts with a classical based work-energy theorem and applies SR's momentum to the derivation. One outcome of this derivation is relativistic kinetic energy. From this derivation, it is rather straight forward to form a kinetic energy based time dilation function. In the derivation of General Relativity a common approach is to bypass classical laws as a starting point. Instead a rigorous development of differential geometry and Riemannian space is constructed, from which classical based laws are derived. This is in contrast to SR's approach of starting with classical laws and applying the consequences of the universal speed of light by all observers. A possible method to derive time dilation due to Newtonian gravitational potential energy (NGPE) is to apply SR's approach to deriving relativistic kinetic energy. It will be shown this method gives a first order accuracy compared to Schwarzschild's metric. The SR's kinetic energy and the newly derived NGPE derivation are combined to form a Riemannian metric based on these two energies. A geodesic is derived and calculations compared to Schwarzschild's geodesic for an orbiting test mass about a central, non-rotating, non-charged massive body. The new metric results in high accuracy calculations when compared to Einsteins General Relativity's prediction. The new method provides a candidate approach for starting with classical laws and deriving General Relativity effects. This approach mimics SR's method of starting with classical mechanics when deriving relativistic equations. As a compliment to introducing General Relativity, it provides a plausible scaffolding method from classical physics when teaching introductory General Relativity. A straight forward path from classical laws to General Relativity will be derived. This derivation

Learning Peri-saccadic Remapping of Receptive Field from Experience in Lateral Intraparietal Area

Directory of Open Access Journals (Sweden)

Xiao Wang

2017-11-01

Full Text Available Our eyes move constantly at a frequency of 3–5 times per second. These movements, called saccades, induce the sweeping of visual images on the retina, yet we perceive the world as stable. It has been suggested that the brain achieves this visual stability via predictive remapping of neuronal receptive field (RF. A recent experimental study disclosed details of this remapping process in the lateral intraparietal area (LIP, that is, about the time of the saccade, the neuronal RF expands along the saccadic trajectory temporally, covering the current RF (CRF, the future RF (FRF, and the region the eye will sweep through during the saccade. A cortical wave (CW model was also proposed, which attributes the RF remapping as a consequence of neural activity propagating in the cortex, triggered jointly by a visual stimulus and the corollary discharge (CD signal responsible for the saccade. In this study, we investigate how this CW model is learned naturally from visual experiences at the development of the brain. We build a two-layer network, with one layer consisting of LIP neurons and the other superior colliculus (SC neurons. Initially, neuronal connections are random and non-selective. A saccade will cause a static visual image to sweep through the retina passively, creating the effect of the visual stimulus moving in the opposite direction of the saccade. According to the spiking-time-dependent-plasticity rule, the connection path in the opposite direction of the saccade between LIP neurons and the connection path from SC to LIP are enhanced. Over many such visual experiences, the CW model is developed, which generates the peri-saccadic RF remapping in LIP as observed in the experiment.

Health Challenges in Refugee Reception: Dateline Europe 2016

Science.gov (United States)

Blitz, Brad K.; d’Angelo, Alessio; Kofman, Eleonore; Montagna, Nicola

2017-01-01

The arrival of more than one million migrants, many of them refugees, has proved a major test for the European Union. Although international relief and monitoring agencies have been critical of makeshift camps in Calais and Eidomeni where infectious disease and overcrowding present major health risks, few have examined the nature of the official reception system and its impact on health delivery. Drawing upon research findings from an Economic and Social Research Council (ESRC) funded project, this article considers the physical and mental health of asylum–seekers in transit and analyses how the closure of borders has engendered health risks for populations in recognised reception centres in Sicily and in Greece. Data gathered by means of a survey administered in Greece (300) and in Sicily (400), and complemented by in-depth interviews with migrants (45) and key informants (50) including representatives of government offices, humanitarian and relief agencies, NGOs and activist organisations, are presented to offer an analysis of the reception systems in the two frontline states. We note that medical provision varies significantly from one centre to another and that centre managers play a critical role in the transmission of vital information. A key finding is that, given such disparity, the criteria used by the UNHCR to grade health services reception do not address the substantive issue that prevent refugees from accessing health services, even when provided on site. Health provision is not as recorded in UNHCR reporting but rather there are critical gaps between provision, awareness, and access for refugees in reception systems in Sicily and in Greece. This article concludes that there is a great need for more information campaigns to direct refugees to essential services. PMID:29189766

Health Challenges in Refugee Reception: Dateline Europe 2016

Directory of Open Access Journals (Sweden)

Brad K. Blitz

2017-11-01

Full Text Available The arrival of more than one million migrants, many of them refugees, has proved a major test for the European Union. Although international relief and monitoring agencies have been critical of makeshift camps in Calais and Eidomeni where infectious disease and overcrowding present major health risks, few have examined the nature of the official reception system and its impact on health delivery. Drawing upon research findings from an Economic and Social Research Council (ESRC funded project, this article considers the physical and mental health of asylum–seekers in transit and analyses how the closure of borders has engendered health risks for populations in recognised reception centres in Sicily and in Greece. Data gathered by means of a survey administered in Greece (300 and in Sicily (400, and complemented by in-depth interviews with migrants (45 and key informants (50 including representatives of government offices, humanitarian and relief agencies, NGOs and activist organisations, are presented to offer an analysis of the reception systems in the two frontline states. We note that medical provision varies significantly from one centre to another and that centre managers play a critical role in the transmission of vital information. A key finding is that, given such disparity, the criteria used by the UNHCR to grade health services reception do not address the substantive issue that prevent refugees from accessing health services, even when provided on site. Health provision is not as recorded in UNHCR reporting but rather there are critical gaps between provision, awareness, and access for refugees in reception systems in Sicily and in Greece. This article concludes that there is a great need for more information campaigns to direct refugees to essential services.

Internal tilting and classical transport for field-reversed configurations based on the Maschke--Hernegger solution

International Nuclear Information System (INIS)

Clemente, R.A.; Grillo, C.E.

1984-01-01

It is shown that elongated field-reversed configurations based on the Maschke--Hernegger solution of the Grad--Shafranov equation are unstable to internal tilting. The particle transport properties across the flux surfaces of such a model are also considered in the limit of large elongation of the separatrix. An estimation of the time of confinement of particles in terms of classical conductivity, which is lower than previous estimates, is given

Origin of classical structure in the Universe

Energy Technology Data Exchange (ETDEWEB)

Kiefer, Claus [Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Cologne (Germany); Lohmar, Ingo [Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Cologne (Germany); Polarski, David [Laboratoire de Physique Theorique et Astroparticules, UMR 5207 CNRS, Universite de Montpellier II, 34095 Montpellier (France); Starobinsky, Alexei A [Landau Institute for Theoretical Physics, Kosygina St. 2, Moscow 119334 (Russian Federation)

2007-05-15

We address the quantum-to-classical transition for primordial fluctuations, that is, the emergence of classical stochastic properties for these fluctuations. We discuss in particular the entanglement entropy for these fluctuations, the decoherence time, and the question of the classical basis (pointer basis) for them. The decoherence time for modes outside the Hubble scale is set by the Hubble parameter. The classical states are narrow Gaussians in the field amplitude.

Theoretical physics 3. Classical field theory. On electrodynamics, non-Abelian gauge theories, and gravitation. 4. ed.; Theoretische Physik 3. Klassische Feldtheorie. Von Elektrodynamik, nicht-Abelschen Eichtheorien und Gravitation

Energy Technology Data Exchange (ETDEWEB)

Scheck, Florian [Mainz Univ. (Germany). Inst. fuer Physik

2017-09-01

The following topics are dealt with: Maxwell's equations together with their symmetry and covariance, the Maxwell theory as classical field theory, simple applications of Maxwell's theory, local gauge theories, classical field theory of gravitation. (HSI)

Deviations from Newton's law in supersymmetric large extra dimensions

International Nuclear Information System (INIS)

Callin, P.; Burgess, C.P.

2006-01-01

Deviations from Newton's inverse-squared law at the micron length scale are smoking-gun signals for models containing supersymmetric large extra dimensions (SLEDs), which have been proposed as approaches for resolving the cosmological constant problem. Just like their non-supersymmetric counterparts, SLED models predict gravity to deviate from the inverse-square law because of the advent of new dimensions at sub-millimeter scales. However SLED models differ from their non-supersymmetric counterparts in three important ways: (i) the size of the extra dimensions is fixed by the observed value of the dark energy density, making it impossible to shorten the range over which new deviations from Newton's law must be seen; (ii) supersymmetry predicts there to be more fields in the extra dimensions than just gravity, implying different types of couplings to matter and the possibility of repulsive as well as attractive interactions; and (iii) the same mechanism which is purported to keep the cosmological constant naturally small also keeps the extra-dimensional moduli effectively massless, leading to deviations from general relativity in the far infrared of the scalar-tensor form. We here explore the deviations from Newton's law which are predicted over micron distances, and show the ways in which they differ and resemble those in the non-supersymmetric case

Advertising Receptivity and Youth Initiation of Smokeless Tobacco.

Science.gov (United States)

Timberlake, David S

2016-07-28

Cross-sectional data suggests that adolescents' receptivity to the advertising of smokeless tobacco is correlated with use of chewing tobacco or snuff. Lack of longitudinal data has precluded determination of whether advertising receptivity precedes or follows initiation of smokeless tobacco. The objective of this study was to test for the association between advertising receptivity and subsequent initiation of smokeless tobacco among adolescent males. Adolescent males from the 1993-1999 Teen Longitudinal California Tobacco Survey were selected at the baseline survey for never having used smokeless tobacco. Separate longitudinal analyses corresponded to two dependent variables, ever use of smokeless tobacco (1993-1996; N = 1,388) and use on 20 or more occasions (1993-1999; N = 1,014). Models were adjusted for demographic variables, risk factors for smokeless tobacco use, and exposure to users of smokeless tobacco. Advertising receptivity at baseline was predictive of ever use by late adolescence (RR(95% CI) = 2.0 (1.5, 2.8)) and regular use by young adulthood (RR(95% CI) = 3.7 (2.1, 6.7)) in models that were adjusted for covariates. Conclusions/ Importance: The findings challenge the tobacco industry's assertion that tobacco marketing does not impact youth initiation. This is particularly relevant to tobacco control in the United States because the 2009 Tobacco Control Act places fewer restrictions on smokeless tobacco products compared to cigarettes.

Classical and quantum dynamics from classical paths to path integrals

CERN Document Server

Dittrich, Walter

2017-01-01

Graduate students who wish to become familiar with advanced computational strategies in classical and quantum dynamics will find in this book both the fundamentals of a standard course and a detailed treatment of the time-dependent oscillator, Chern-Simons mechanics, the Maslov anomaly and the Berry phase, to name just a few topics. Well-chosen and detailed examples illustrate perturbation theory, canonical transformations and the action principle, and demonstrate the usage of path integrals. The fifth edition has been revised and enlarged to include chapters on quantum electrodynamics, in particular, Schwinger’s proper time method and the treatment of classical and quantum mechanics with Lie brackets and pseudocanonical transformations. It is shown that operator quantum electrodynamics can be equivalently described with c-numbers, as demonstrated by calculating the propagation function for an electron in a prescribed classical electromagnetic field.

Longitudinal analysis of receptive vocabulary growth in young Spanish English-speaking children from migrant families.

Science.gov (United States)

Jackson, Carla Wood; Schatschneider, Christopher; Leacox, Lindsey

2014-01-01

The authors of this study described developmental trajectories and predicted kindergarten performance of Spanish and English receptive vocabulary acquisition of young Latino/a English language learners (ELLs) from socioeconomically disadvantaged migrant families. In addition, the authors examined the extent to which gender and individual initial performance in Spanish predict receptive vocabulary performance and growth rate. The authors used hierarchical linear modeling of 64 children's receptive vocabulary performance to generate growth trajectories, predict performance at school entry, and examine potential predictors of rate of growth. The timing of testing varied across children. The ELLs (prekindergarten to 2nd grade) participated in 2-5 testing sessions, each 6-12 months apart. The ELLs' average predicted standard score on an English receptive vocabulary at kindergarten was nearly 2 SDs below the mean for monolingual peers. Significant growth in the ELLs' receptive vocabulary was observed between preschool and 2nd grade, indicating that the ELLs were slowly closing the receptive vocabulary gap, although their average score remained below the standard score mean for age-matched monolingual peers. The ELLs demonstrated a significant decrease in Spanish receptive vocabulary standard scores over time. Initial Spanish receptive vocabulary was a significant predictor of growth in English receptive vocabulary. High initial Spanish receptive vocabulary was associated with greater growth in English receptive vocabulary and decelerated growth in Spanish receptive vocabulary. Gender was not a significant predictor of growth in either English or Spanish receptive vocabulary. ELLs from low socioeconomic backgrounds may be expected to perform lower in English compared with their monolingual English peers in kindergarten. Performance in Spanish at school entry may be useful in identifying children who require more intensive instructional support for English vocabulary

Derivation of the blackbody radiation spectrum from the equivalence principle in classical physics with classical electromagnetic zero-point radiation

International Nuclear Information System (INIS)

Boyer, T.H.

1984-01-01

A derivation of Planck's spectrum including zero-point radiation is given within classical physics from recent results involving the thermal effects of acceleration through classical electromagnetic zero-point radiation. A harmonic electric-dipole oscillator undergoing a uniform acceleration a through classical electromagnetic zero-point radiation responds as would the same oscillator in an inertial frame when not in zero-point radiation but in a different spectrum of random classical radiation. Since the equivalence principle tells us that the oscillator supported in a gravitational field g = -a will respond in the same way, we see that in a gravitational field we can construct a perpetual-motion machine based on this different spectrum unless the different spectrum corresponds to that of thermal equilibrium at a finite temperature. Therefore, assuming the absence of perpetual-motion machines of the first kind in a gravitational field, we conclude that the response of an oscillator accelerating through classical zero-point radiation must be that of a thermal system. This then determines the blackbody radiation spectrum in an inertial frame which turns out to be exactly Planck's spectrum including zero-point radiation

Classical and Quantum Chaos in Atom Optics

OpenAIRE

Saif, Farhan

2006-01-01

The interaction of an atom with an electromagnetic field is discussed in the presence of a time periodic external modulating force. It is explained that a control on atom by electromagnetic fields helps to design the quantum analog of classical optical systems. In these atom optical systems chaos may appear at the onset of external fields. The classical and quantum chaotic dynamics is discussed, in particular in an atom optics Fermi accelerator. It is found that the quantum dynamics exhibits ...

Classical algebraic chromodynamics

International Nuclear Information System (INIS)

Adler, S.L.

1978-01-01

I develop an extension of the usual equations of SU(n) chromodynamics which permits the consistent introduction of classical, noncommuting quark source charges. The extension involves adding a singlet gluon, giving a U(n) -based theory with outer product P/sup a/(u,v) = (1/2)(d/sup a/bc + if/sup a/bc)(u/sup b/v/sup c/ - v/sup b/u/sup c/) which obeys the Jacobi identity, inner product S (u,v) = (1/2)(u/sup a/v/sup a/ + v/sup a/u/sup a/), and with the n 2 gluon fields elevated to algebraic fields over the quark color charge C* algebra. I show that provided the color charge algebra satisfies the condition S (P (u,v),w) = S (u,P (v,w)) for all elements u,v,w of the algebra, all the standard derivations of Lagrangian chromodynamics continue to hold in the algebraic chromodynamics case. I analyze in detail the color charge algebra in the two-particle (qq, qq-bar, q-barq-bar) case and show that the above consistency condition is satisfied for the following unique (and, interestingly, asymmetric) choice of quark and antiquark charges: Q/sup a//sub q/ = xi/sup a/, Q/sup a//sub q/ = xi-bar/sup a/ + delta/sup a/0(n/2)/sup 3/2/1, with xi/sup a/xi/sup b/ = (1/2)(d/sup a/bc + if/sup a/bc) xi/sup c/, xi-bar/sup a/xi-bar/sup b/ = -(1/2)(d/sup a/bc - if/sup a/bc) xi-bar/sup c/. The algebraic structure of the two-particle U(n) force problem, when expressed on an appropriately diagonalized basis, leads for all n to a classical dynamics problem involving an ordinary SU(2) Yang-Mills field with uniquely specified classical source charges which are nonparallel in the color-singlet state. An explicit calculation shows that local algebraic U(n) gauge transformations lead only to a rigid global rotation of axes in the overlying classical SU(2) problem, which implies that the relative orientations of the classical source charges have physical significance

Quantum-to-classical transition and gravity-induced instabilities (in progress)

International Nuclear Information System (INIS)

Lima, William C.C.

2013-01-01

Full text: It has been argued that gravitational fields produced by realistic matter distributions can induce the vacuum fluctuations of some non-minimally coupled free scalar field to go through a phase of exponential amplification. For the particular case of the formation of a neutron star, the energy density of the field in its initial vacuum state rivals the one of the star in a lapse of just a few milliseconds after the effect has been triggered. From this point on back reaction effects must be taken into account in order to predict the fate of both the star and scalar field. Classical analyses have shown that, at least for some values of the mass-radius ratio of the star and the non-minimal coupling parameter, a non-null scalar field profile could stabilize the system. The aim of our study is to shed some light on the back reaction process from the perspective of the quantum-to-classical transition that will occur once the classical background spacetime reacts to the unstable quantum field. In particular, the transition to a classical regime requires the specification of a well-defined classical initial state for the field. This can be accomplished analyzing the quantum state of the field around the time back reaction effects become important. (author)

Classical and quantum chaos in atom optics

International Nuclear Information System (INIS)

Saif, Farhan

2005-01-01

The interaction of an atom with an electro-magnetic field is discussed in the presence of a time periodic external modulating force. It is explained that a control on atom by electro-magnetic fields helps to design the quantum analog of classical optical systems. In these atom optical systems chaos may appear at the onset of external fields. The classical and quantum chaotic dynamics is discussed, in particular in an atom optics Fermi accelerator. It is found that the quantum dynamics exhibits dynamical localization and quantum recurrences

Classical field theory in the space of reference frames. [Space-time manifold, action principle

Energy Technology Data Exchange (ETDEWEB)

Toller, M [Dipartimento di Matematica e Fisica, Libera Universita, Trento (Italy)

1978-03-11

The formalism of classical field theory is generalized by replacing the space-time manifold M by the ten-dimensional manifold S of all the local reference frames. The geometry of the manifold S is determined by ten vector fields corresponding to ten operationally defined infinitesimal transformations of the reference frames. The action principle is written in terms of a differential 4-form in the space S (the Lagrangian form). Densities and currents are represented by differential 3-forms in S. The field equations and the connection between symmetries and conservation laws (Noether's theorem) are derived from the action principle. Einstein's theory of gravitation and Maxwell's theory of electromagnetism are reformulated in this language. The general formalism can also be used to formulate theories in which charge, energy and momentum cannot be localized in space-time and even theories in which a space-time manifold cannot be defined exactly in any useful way.

Compressibility effects on the non-linear receptivity of boundary layers to dielectric barrier discharges

Science.gov (United States)

Denison, Marie F. C.

The reduction of drag and aerodynamic heating caused by boundary layer transition is of central interest for the development of hypersonic vehicles. Receptivity to flow perturbation in the form of Tollmien-Schlichting (TS) wave growth often determines the first stage of the transition process, which can be delayed by depositing specific excitations into the boundary layer. Weakly ionized Dielectric Barrier Discharge (DBD) actuators are being investigated as possible sources of such excitations, but little is known today about their interaction with high-speed flows. In this framework, the first part of the thesis is dedicated to a receptivity study of laminar compressible boundary layers over a flat plate by linear stability analysis following an adjoint operator formulation, under DBD representative excitations assumed independent of flow conditions. The second part of the work concentrates on the development of a coupled plasma-Navier and Stokes solver targeted at the study of supersonic flow and compressibility effects on DBD forcing and non-parallel receptivity. The linear receptivity study of quasi-parallel compressible flows reveals several interesting features such as a significant shift of the region of maximum receptivity deeper into the flow at high Mach number and strong wave amplitude reduction compared to incompressible flows. The response to DBD relevant excitation distributions and to variations of the base flow conditions and system length scales follows these trends. Observed absolute amplitude changes and relative sensitivity modifications between source types are related to the evolution of the offset between forcing peak profile and relevant adjoint mode maximum. The analysis highlights the crucial importance of designing and placing the actuator in a way that matches its force field to the position of maximum boundary layer receptivity for the specific flow conditions of interest. In order to address the broad time and length scale spectrum

The Foucault-Habermas Debate: the Reflexive and Receptive Aspects of Critique

DEFF Research Database (Denmark)

Hansen, Ejvind

2005-01-01

In this paper I discuss the relationship between two different approaches to critical theory – the reflective and the receptive approaches. I show how it can be fruitful to discuss the relationship between Habermas and Foucault through this distinction. My point is that whereas Habermas focusses...... on critique as a reflexive activity, Foucault mainly focusses on the receptive conditions for critique to be possible. I argue further that Foucault focusses on the receptive aspects of critique, the quest for universality is not as pressing as it is in Habermas’ approach, because problematizing critique can...

Preheating with extra dimensions

International Nuclear Information System (INIS)

Tsujikawa, S.

2000-01-01

We investigate preheating in a higher-dimensional generalized Kaluza-Klein theory with a quadratic inflaton potential V(/φ) = /frac12 m 2 /φ 2 including metric perturbations explicitly. The system we consider is the multi-field model where there exists a dilaton field /σ which corresponds to the scale of compactifications and another scalar field /χ coupled to inflaton with the interaction frac12 g 2 /φ 2 /χ 2 +/g-tilde 2 /φ 3 /χ. In the case of g-tilde=0, we find that the perturbation of dilaton does not undergo parametric amplification while the χ field fluctuation can be enhanced in the usual manner by parametric resonance. In the presence of the /g-tilde 2 /φ 3 /χ coupling, the dilaton fluctuation in sub-Hubble scales is modestly amplified by the growth of metric perturbations for the large coupling g-tilde. In super-Hubble scales, the enhancement of the dilaton fluctuation as well as metric perturbations is weak, taking into account the backreaction effect of created /χ particles. We argue that not only is it possible to predict the ordinary inflationary spectrum in large scales but extra dimensions can be held static during preheating in our scenario. (author)

Deaf Students' Receptive and Expressive American Sign Language Skills: Comparisons and Relations

Science.gov (United States)

Beal-Alvarez, Jennifer S.

2014-01-01

This article presents receptive and expressive American Sign Language skills of 85 students, 6 through 22 years of age at a residential school for the deaf using the American Sign Language Receptive Skills Test and the Ozcaliskan Motion Stimuli. Results are presented by ages and indicate that students' receptive skills increased with age and…

Classical probabilities for Majorana and Weyl spinors

International Nuclear Information System (INIS)

Wetterich, C.

2011-01-01

Highlights: → Map of classical statistical Ising model to fermionic quantum field theory. → Lattice-regularized real Grassmann functional integral for single Weyl spinor. → Emerging complex structure characteristic for quantum physics. → A classical statistical ensemble describes a quantum theory. - Abstract: We construct a map between the quantum field theory of free Weyl or Majorana fermions and the probability distribution of a classical statistical ensemble for Ising spins or discrete bits. More precisely, a Grassmann functional integral based on a real Grassmann algebra specifies the time evolution of the real wave function q τ (t) for the Ising states τ. The time dependent probability distribution of a generalized Ising model obtains as p τ (t)=q τ 2 (t). The functional integral employs a lattice regularization for single Weyl or Majorana spinors. We further introduce the complex structure characteristic for quantum mechanics. Probability distributions of the Ising model which correspond to one or many propagating fermions are discussed explicitly. Expectation values of observables can be computed equivalently in the classical statistical Ising model or in the quantum field theory for fermions.

Quantum epistemology from subquantum ontology: Quantum mechanics from theory of classical random fields

Science.gov (United States)

Khrennikov, Andrei

2017-02-01

The scientific methodology based on two descriptive levels, ontic (reality as it is) and epistemic (observational), is briefly presented. Following Schrödinger, we point to the possible gap between these two descriptions. Our main aim is to show that, although ontic entities may be unaccessible for observations, they can be useful for clarification of the physical nature of operational epistemic entities. We illustrate this thesis by the concrete example: starting with the concrete ontic model preceding quantum mechanics (the latter is treated as an epistemic model), namely, prequantum classical statistical field theory (PCSFT), we propose the natural physical interpretation for the basic quantum mechanical entity-the quantum state ("wave function"). The correspondence PCSFT ↦ QM is not straightforward, it couples the covariance operators of classical (prequantum) random fields with the quantum density operators. We use this correspondence to clarify the physical meaning of the pure quantum state and the superposition principle-by using the formalism of classical field correlations. In classical mechanics the phase space description can be considered as the ontic description, here states are given by points λ =(x , p) of phase space. The dynamics of the ontic state is given by the system of Hamiltonian equations.We can also consider probability distributions on the phase space (or equivalently random variables valued in it). We call them probabilistic ontic states. Dynamics of probabilistic ontic states is given by the Liouville equation.In classical physics we can (at least in principle) measure both the coordinate and momentum and hence ontic states can be treated as epistemic states as well (or it is better to say that here epistemic states can be treated as ontic states). Probabilistic ontic states represent probabilities for outcomes of joint measurement of position and momentum.However, this was a very special, although very important, example of

Minding one's P's and Q's: From the one loop effective action in quantum field theory to classical transport theory

International Nuclear Information System (INIS)

Jalilian-Marian, Jamal; Jeon, Sangyong; Venugopalan, Raju; Wirstam, Jens

2000-01-01

The one loop effective action in quantum field theory can be expressed as a quantum mechanical path integral over world lines, with internal symmetries represented by Grassmanian variables. In this paper, we develop a real time, many body, world line formalism for the one loop effective action. In particular, we study hot QCD and obtain the classical transport equations which, as Litim and Manuel have shown, reduce in the appropriate limit to the non-Abelian Boltzmann-Langevin equation first obtained by Boedeker. In the Vlasov limit, the classical kinetic equations are those that correspond to the hard thermal loop effective action. We also discuss the imaginary time world line formalism for a hot φ 4 theory, and elucidate its relation to classical transport theory. (c) 2000 The American Physical Society

Quantization in the neighborhood of a classical solution in the theory of a Fermi field

International Nuclear Information System (INIS)

Sveshnikov, K.A.

1988-01-01

The quantization of a Fermi-Bose field system in the neighborhood of a classical solution of the equations of motion that contains both bosonic and spinor components is considered. The latter is regarded as an absolutely anticommuting (Grassmann) component of a fermion field. On account of the transport of the fermion number, such an object mixes the fermionic and bosonic and fermionic and antifermionic degrees of freedom already at the level of the single-particle states (in the approximately of quadratic forms). Explicit expressions are obtained for the operator of the S matrix, which describes such transport processes, and the total Hamiltonian and total fermion charge of the system in this approximation

The Receptive Side of Teaching

Science.gov (United States)

Hruska, Barbara

2008-01-01

When observing teachers in action, one is likely to witness explaining, modeling, managing, guiding, and encouraging. These expressive behaviors constitute a directive force moving outward from teacher to students. Though less visible to an outside observer, teaching also requires receptive skills, the ability to take in information by being fully…

Quantum solitons and their classical relatives. II. ''Fermion--boson reciprocity'' and classical versus quantum problem for the sine-Gordon system

International Nuclear Information System (INIS)

Garbaczewski, P.

1981-01-01

Both quantum and classical sine--Gordon fields can be built out of the fundamental free neutral massive excitations, which quantally obey the Bose--Einstein statistics. At the roots of the ''boson-fermion reciprocity'' invented by Coleman, lies the spin 1/2 approximation of the underlying Bose system. By generalizing the coherent state methods to incorporate non-Fock quantum structures and to give account of the so-called boson transformation theory, we construct the carrier Hilbert space H/sub SG/ for quantum soliton operators. The h→0 limit of state expectation values of these operators among pure coherentlike states in H/sub SG/ reproduces the classical sine--Gordon field. The related (classical and quantum) spin 1/2 xyz Heisenberg model field is built out of the fundamental sine--Gordon excitations, and hence can be consistently defined on the appropriate subset of the quantum soliton Hilbert space H/sub x/yz . A correct classical limit is here shown to arise for the Heisenberg system: phase manifolds of the classical Heisenberg and sine--Gordon systems cannot be then viewed independently as a consequence of the quantum relation

The Distancing-Embracing model of the enjoyment of negative emotions in art reception.

Science.gov (United States)

Menninghaus, Winfried; Wagner, Valentin; Hanich, Julian; Wassiliwizky, Eugen; Jacobsen, Thomas; Koelsch, Stefan

2017-01-01

Why are negative emotions so central in art reception far beyond tragedy? Revisiting classical aesthetics in the light of recent psychological research, we present a novel model to explain this much discussed (apparent) paradox. We argue that negative emotions are an important resource for the arts in general, rather than a special license for exceptional art forms only. The underlying rationale is that negative emotions have been shown to be particularly powerful in securing attention, intense emotional involvement, and high memorability, and hence is precisely what artworks strive for. Two groups of processing mechanisms are identified that conjointly adopt the particular powers of negative emotions for art's purposes. The first group consists of psychological distancing mechanisms that are activated along with the cognitive schemata of art, representation, and fiction. These schemata imply personal safety and control over continuing or discontinuing exposure to artworks, thereby preventing negative emotions from becoming outright incompatible with expectations of enjoyment. This distancing sets the stage for a second group of processing components that allow art recipients to positively embrace the experiencing of negative emotions, thereby rendering art reception more intense, more interesting, more emotionally moving, more profound, and occasionally even more beautiful. These components include compositional interplays of positive and negative emotions, the effects of aesthetic virtues of using the media of (re)presentation (musical sound, words/language, color, shapes) on emotion perception, and meaning-making efforts. Moreover, our Distancing-Embracing model proposes that concomitant mixed emotions often help integrate negative emotions into altogether pleasurable trajectories.

Developmental Stages in Receptive Grammar Acquisition: A Processability Theory Account

Science.gov (United States)

Buyl, Aafke; Housen, Alex

2015-01-01

This study takes a new look at the topic of developmental stages in the second language (L2) acquisition of morphosyntax by analysing receptive learner data, a language mode that has hitherto received very little attention within this strand of research (for a recent and rare study, see Spinner, 2013). Looking at both the receptive and productive…

Regulation regarding the reception of the construction works and the corresponding installations in Romania

Directory of Open Access Journals (Sweden)

Simona Chirică

2017-12-01

Full Text Available The new Regulation regarding the reception of construction works and corresponding installations, approved by Government's Decision no. 347/2017 (“Regulation 2017” has general applicability for all construction works for which there is an obligation to obtain a building permit. Regulation 2017 brings significant changes and clarifications expected by the real estate sector regarding: (i the composition of the commissions involved in the reception procedure, (ii the role of the site supervisor who thus gains significant participation in the reception procedure, and (iii the participation of the public authorities' representatives at the reception, having the veto right on the decision of the reception commission upon the completion of the construction works. Another element of novelty brought by Regulation 2017 is the possibility to do the reception upon the completion of the construction works, respectively the final reception for parts / objectives / sectors of or from the building, if they are distinct/ independent from a physical and functional point of view. Thus, the new regulation facilitates the procedure of authorizing investment objectives and the costs of the process. The partial reception is another innovation brought by the Regulation 2017 in support of the investor, who can thus take over a part of the construction, at a certain stage, and obtain its registration with the Land Book.

High prevalence of extra-genital chlamydial or gonococcal infections among men who have sex with men and transgender women in Lima, Peru.

Science.gov (United States)

Allan-Blitz, Lao-Tzu; Leon, Segundo R; Bristow, Claire C; Konda, Kelika A; Vargas, Silver K; Flores, Juan A; Brown, Brandon J; Caceres, Carlos F; Klausner, Jeffrey D

2017-02-01

Chlamydia trachomatis and Neisseria gonorrhoeae are among the most common sexually transmitted bacterial infections in the world. Data are limited, however, on the burden of extra-genital chlamydial and gonococcal infections among men who have sex with men and transgender women in Lima, Peru. Data were gathered from self-collected anal or pharyngeal swabs from participants in Lima, Peru, and analyzed via cross-sectional methods. Prevalence ratios for the association between extra-genital infection with socio-demographic and sexual behaviors were determined. Overall, 127 (32.8%) participants had anal or pharyngeal infections. On multivariate modeling, anal infection was positively associated with practicing both receptive and insertive anal sex, when compared to insertive alone (PR = 2.49; 95% CI = 1.32-4.71), and negatively associated with any antibiotic use in the prior three months (PR = 0.60; 95% CI = 0.39-0.91). Pharyngeal infection was negatively associated with age greater than 30 years compared to 18-30 years (PR = 0.54; 95% CI = 0.30-0.96), and positively associated with gender identity of transgender women (PR = 2.12; 95% CI = 1.20-3.73). This study demonstrates considerable burden of extra-genital chlamydial and gonococcal infections among men who have sex with men and transgender women in Lima, Peru.

Communication from Goods Reception services

CERN Multimedia

2007-01-01

Members of the personnel are invited to take note that only parcels corresponding to official orders or contracts will be handled at CERN. Individuals are not authorised to have private merchandise delivered to them at CERN and private deliveries will not be accepted by the Goods Reception services. Thank you for your understanding.

EXTRA-OSSEOUS EWING SARCOMA

NARCIS (Netherlands)

van den Berg, Hendrik; Heinen, Richard C.; van der Pal, Heleen J.; Merks, Johannes H. M.

2009-01-01

Background: Clinical data and data on outcome of extra-osseous Ewing tumors are scarce. Procedure: After a search for Ewing tumors in the database of a single institution over a period of 20 years, 16 out of 192 cases were found to have extra-osseous primary tumors. Results: Ages at initial

Interaction between benzenedithiolate and gold: Classical force field for chemical bonding

Science.gov (United States)

Leng, Yongsheng; Krstić, Predrag S.; Wells, Jack C.; Cummings, Peter T.; Dean, David J.

2005-06-01

We have constructed a group of classical potentials based on ab initio density-functional theory (DFT) calculations to describe the chemical bonding between benzenedithiolate (BDT) molecule and gold atoms, including bond stretching, bond angle bending, and dihedral angle torsion involved at the interface between the molecule and gold clusters. Three DFT functionals, local-density approximation (LDA), PBE0, and X3LYP, have been implemented to calculate single point energies (SPE) for a large number of molecular configurations of BDT-1, 2 Au complexes. The three DFT methods yield similar bonding curves. The variations of atomic charges from Mulliken population analysis within the molecule/metal complex versus different molecular configurations have been investigated in detail. We found that, except for bonded atoms in BDT-1, 2 Au complexes, the Mulliken partial charges of other atoms in BDT are quite stable, which significantly reduces the uncertainty in partial charge selections in classical molecular simulations. Molecular-dynamics (MD) simulations are performed to investigate the structure of BDT self-assembled monolayer (SAM) and the adsorption geometry of S adatoms on Au (111) surface. We found that the bond-stretching potential is the most dominant part in chemical bonding. Whereas the local bonding geometry of BDT molecular configuration may depend on the DFT functional used, the global packing structure of BDT SAM is quite independent of DFT functional, even though the uncertainty of some force-field parameters for chemical bonding can be as large as ˜100%. This indicates that the intermolecular interactions play a dominant role in determining the BDT SAMs global packing structure.

Equivariant Reduction of Gauge Theories over Fuzzy Extra Dimensions

International Nuclear Information System (INIS)

Kürkçüoglu, Seçkin

2012-01-01

In SU(N) Yang-Mills theories on a manifold M, which are suitably coupled to a set of scalars, fuzzy spheres may be generated as extra dimensions by spontaneous symmetry breaking. This process results in gauge theories over the product space of the manifold M and the fuzzy spheres with smaller gauge groups. Here we present the SU(2)– and SU(2) × SU(2)-equivariant parametrization of U(2) and U(4) gauge fields on S 2 F and S 2 F × S 2 F respectively and outline the dimensional reduction of these theories over the fuzzy extra dimensions. The emerging dimensionally reduced theories are Higgs type models. Some vortex type solutions of these theories are briefly discussed.

Flavor at the TeV scale with extra dimensions

International Nuclear Information System (INIS)

Arkani-Hamed, Nima; Hall, Lawrence; Smith, David; Weiner, Neal

2000-01-01

Theories where the standard model fields reside on a 3-brane, with a low fundamental cutoff and extra dimensions, provide alternative solutions to the gauge hierarchy problem. However, generating flavor at the TeV scale while avoiding flavor-changing difficulties appears prohibitively difficult at first sight. We argue to the contrary that this picture allows us to lower flavor physics close to the TeV scale. Small Yukawa couplings are generated by ''shining'' badly broken flavor symmetries from distant branes, and flavor and CP-violating processes are adequately suppressed by these symmetries. We further show how the extra dimensions avoid four dimensional disasters associated with light fields charged under flavor. We construct elegant and realistic theories of flavor based on the maximal U(3) 5 flavor symmetry which naturally generate the simultaneous hierarchy of masses and mixing angles. Finally, we introduce a new framework for predictive theories of flavor, where our 3-brane is embedded within highly symmetrical configurations of higher-dimensional branes. (c) 2000 The American Physical Society

The receptive-expressive gap in the vocabulary of young second-language learners: Robustness and possible mechanisms

OpenAIRE

Gibson, Todd A.; Oller, D. Kimbrough; Jarmulowicz, Linda; Ethington, Corinna A.

2012-01-01

Adults and children learning a second language show difficulty accessing expressive vocabulary that appears accessible receptively in their first language (L1). We call this discrepancy the receptive-expressive gap. Kindergarten Spanish (L1) - English (L2) sequential bilinguals were given standardized tests of receptive and expressive vocabulary in both Spanish and English. We found a small receptive-expressive gap in English but a large receptive-expressive gap in Spanish. We categorized chi...

A search for extra-solar planetary transits in the field of open cluster NGC 6819

Science.gov (United States)

Street, Rachel Amanda

The technique of searching for extra-solar planetary transits is investigated. This technique, which relies on detecting the brief, shallow eclipses caused by planets passing across the line of sight to the primary star, requires high-precision time-series photometry of large numbers of stars in order to detect these statistically rare events. Observations of 18000 stars in the field including the intermediate-age open cluster NGC 6819 are presented. This target field constrasts with the stellar environment surveyed by the radial velocity technique, which concentrates on the Solar neighbourhood. I present the data-reduction techniques used to obtain high-precision photometry in a semi-automated fashion for tens of thousands of stars at a time, together with an algorithm designed to search the resulting lightcurves for the transit signatures of hot Jupiter type planets. I describe simulations designed to test the detection efficiency of this algorithm and, for comparison, predict the number of transits expected from this data, assuming that hot Jupiter planets similar to HD 209458 are as common in the field of NGC 6819 as they are in the Solar neighbourhood. While no planetary transits have yet been identified, the detection of several very low amplitude eclipses by stellar companions demonstrates the effectiveness of the method. This study also indicates that stellar activity and particularly blending are significant causes of false detections. A useful additional consequence of studying this time-series photometry is the census it provides of some of the variable stars in the field. I report on the discovery of a variety of newly-discovered variables, including Algol-type detached eclipsing binaries which are likely to consist of M-dwarf stars. Further study of these stars is strongly recommended in order to help constrain models of stellar structure at the very low mass end. I conclude with a summary of this work in the context of other efforts being made in this

Citation Classics from Industrial Marketing Management

DEFF Research Database (Denmark)

Lindgreen, Adam; Di Benedetto, C. Anthony

2017-01-01

, system sellers and systems integrator, third-party logistics providers, and value). Finally, each of the 30 citation classics is introduced, and the classics' theoretical implications to business-to-business marketing management and fields related to (e.g., supply chain management, strategic management......This article proposes a categorization of what constitutes a citation classic. General observations reveal, with regard to the top 30 citation classics from Industrial Marketing Management, the number of authors per article, country of origin of the lead author, and type of article (literature...... review, qualitative methodology, or quantitative methodology). In addition, these citation classics can be classified by topic (firm performance, goods-dominant and service-dominant logics, Internet and high-technology markets, product innovation, relationships and business networks, supply chains...

Combined Docking with Classical Force Field and Quantum Chemical Semiempirical Method PM7

Directory of Open Access Journals (Sweden)

A. V. Sulimov

2017-01-01

Full Text Available Results of the combined use of the classical force field and the recent quantum chemical PM7 method for docking are presented. Initially the gridless docking of a flexible low molecular weight ligand into the rigid target protein is performed with the energy function calculated in the MMFF94 force field with implicit water solvent in the PCM model. Among several hundred thousand local minima, which are found in the docking procedure, about eight thousand lowest energy minima are chosen and then energies of these minima are recalculated with the recent quantum chemical semiempirical PM7 method. This procedure is applied to 16 test complexes with different proteins and ligands. For almost all test complexes such energy recalculation results in the global energy minimum configuration corresponding to the ligand pose near the native ligand position in the crystalized protein-ligand complex. A significant improvement of the ligand positioning accuracy comparing with MMFF94 energy calculations is demonstrated.

Combined Docking with Classical Force Field and Quantum Chemical Semiempirical Method PM7.

Science.gov (United States)

Sulimov, A V; Kutov, D C; Katkova, E V; Sulimov, V B

2017-01-01

Results of the combined use of the classical force field and the recent quantum chemical PM7 method for docking are presented. Initially the gridless docking of a flexible low molecular weight ligand into the rigid target protein is performed with the energy function calculated in the MMFF94 force field with implicit water solvent in the PCM model. Among several hundred thousand local minima, which are found in the docking procedure, about eight thousand lowest energy minima are chosen and then energies of these minima are recalculated with the recent quantum chemical semiempirical PM7 method. This procedure is applied to 16 test complexes with different proteins and ligands. For almost all test complexes such energy recalculation results in the global energy minimum configuration corresponding to the ligand pose near the native ligand position in the crystalized protein-ligand complex. A significant improvement of the ligand positioning accuracy comparing with MMFF94 energy calculations is demonstrated.

First order mean field games - explicit solutions, perturbations and connection with classical mechanics

KAUST Repository

Gomes, Diogo A.

2016-01-06

We present recent developments in the theory of first-order mean-field games (MFGs). A standard assumption in MFGs is that the cost function of the agents is monotone in the density of the distribution. This assumption leads to a comprehensive existence theory and to the uniqueness of smooth solutions. Here, our goals are to understand the role of local monotonicity in the small perturbation regime and the properties of solutions for problems without monotonicity. Under a local monotonicity assumption, we show that small perturbations of MFGs have unique smooth solutions. In addition, we explore the connection between first-order MFGs and classical mechanics and KAM theory. Next, for non-monotone problems, we construct non-unique explicit solutions for a broad class of first-order mean-field games. We provide an alternative formulation of MFGs in terms of a new current variable. These examples illustrate two new phenomena: the non-uniqueness of solutions and the breakdown of regularity.

First order mean field games - explicit solutions, perturbations and connection with classical mechanics

KAUST Repository

Gomes, Diogo A.; Nurbekyan, Levon; Prazeres, Mariana

2016-01-01

We present recent developments in the theory of first-order mean-field games (MFGs). A standard assumption in MFGs is that the cost function of the agents is monotone in the density of the distribution. This assumption leads to a comprehensive existence theory and to the uniqueness of smooth solutions. Here, our goals are to understand the role of local monotonicity in the small perturbation regime and the properties of solutions for problems without monotonicity. Under a local monotonicity assumption, we show that small perturbations of MFGs have unique smooth solutions. In addition, we explore the connection between first-order MFGs and classical mechanics and KAM theory. Next, for non-monotone problems, we construct non-unique explicit solutions for a broad class of first-order mean-field games. We provide an alternative formulation of MFGs in terms of a new current variable. These examples illustrate two new phenomena: the non-uniqueness of solutions and the breakdown of regularity.

Classical Collapse to Black Holes and Quantum Bounces: A Review

Directory of Open Access Journals (Sweden)

Daniele Malafarina

2017-05-01

Full Text Available In the last four decades, different programs have been carried out aiming at understanding the final fate of gravitational collapse of massive bodies once some prescriptions for the behaviour of gravity in the strong field regime are provided. The general picture arising from most of these scenarios is that the classical singularity at the end of collapse is replaced by a bounce. The most striking consequence of the bounce is that the black hole horizon may live for only a finite time. The possible implications for astrophysics are important since, if these models capture the essence of the collapse of a massive star, an observable signature of quantum gravity may be hiding in astrophysical phenomena. One intriguing idea that is implied by these models is the possible existence of exotic compact objects, of high density and finite size, that may not be covered by an horizon. The present article outlines the main features of these collapse models and some of the most relevant open problems. The aim is to provide a comprehensive (as much as possible overview of the current status of the field from the point of view of astrophysics. As a little extra, a new toy model for collapse leading to the formation of a quasi static compact object is presented.

Unaccompanied adolescents seeking asylum: Poorer mental health under a restrictive reception

NARCIS (Netherlands)

Reijneveld, S.A.; Boer, J.B.de; Bean, T.; Korfker, D.G.

2005-01-01

We assessed the effects of a stringent reception policy on the mental health of unaccompanied adolescent asylum seekers by comparing the mental health of adolescents in a restricted campus reception setting and in a setting offering more autonomy (numbers [response rates]: 69 [93%] and 53 [69%],

Time-Dependent Toroidal Compactification Proposals and the Bianchi Type I Model: Classical and Quantum Solutions

Directory of Open Access Journals (Sweden)

L. Toledo Sesma

2016-01-01

Full Text Available We construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. This approach is applied to anisotropic cosmological Bianchi type I model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Under this approach, we present an isotropization mechanism for the Bianchi I cosmological model through the analysis of the ratio between the anisotropic parameters and the volume of the Universe which in general keeps constant or runs into zero for late times. We also find that the presence of extra dimensions in this model can accelerate the isotropization process depending on the momenta moduli values. Finally, we present some solutions to the corresponding Wheeler-DeWitt (WDW equation in the context of standard quantum cosmology.

BELVEDERE® Extra – a new high performance- herbicide in beets

Directory of Open Access Journals (Sweden)

Donati, Alexandra

2014-03-01

Full Text Available Common lambsquarters, cleavers, ladysthumb and wild buckwheat, chamomile, mercury, foolsparsleey and volunteer rapes are only some of the most important weeds in fooder and sugar beets. For the control of classical weed societies farmers can fall back on a limited number of active ingredients. Generally, Phenmedipham (PMP, Desmedipham (DMP and Ethofumesate are the basis of a spray sequence. They are complemented with other active ingredients depending on the specific weed situation. The newly formulated BELVEDERE® Extra combines the three mentioned active ingredients in an optimal ratio. Hence, the herbicide covers a very broad weed spectrum with an excellent efficacy on Common lambsquarters, cleavers, ladysthumb and wild buckwheat. BELVEDERE® EXTRA is a liquid, selective, and systemic herbicide. It is formulated as suspoemulsion so that a high efficacy is achieved while preserving a very good selectivity. The product allows for flexible control of leaf activity as an additive (e.g. OLEO FC is appended. Ethofumesate, which is mainly effective via the roots of the plant, belongs to a different HRAC group than Phenmedipham and Desmedipham. The high concentration of 200 g/L Ethofumesate leads to an effective resistance management especially regarding Fathen and other important weeds. Since 23rd of September 2013 BELVEDERE® extra is registered for post emergence splitting application (3 applications against annual dicotyledonous weeds. The maximum application rate per treatment is 1,3 L/ha. In combination with GOLTIX® TITAN® (Metamitron + Quinmerac or Goltix® Gold (Metamitron the weed spectrum is broadened. Basically, a timely application whose application rates are adapted to the location is essential for a good efficacy of beet herbicides.

Leading-order classical Lagrangians for the nonminimal standard-model extension

Science.gov (United States)

Reis, J. A. A. S.; Schreck, M.

2018-03-01

In this paper, we derive the general leading-order classical Lagrangian covering all fermion operators of the nonminimal standard-model extension (SME). Such a Lagrangian is considered to be the point-particle analog of the effective field theory description of Lorentz violation that is provided by the SME. At leading order in Lorentz violation, the Lagrangian obtained satisfies the set of five nonlinear equations that govern the map from the field theory to the classical description. This result can be of use for phenomenological studies of classical bodies in gravitational fields.

BRST Quantisation of Histories Electrodynamics

OpenAIRE

Noltingk, D.

2001-01-01

This paper is a continuation of earlier work where a classical history theory of pure electrodynamics was developed in which the the history fields have \\emph{five} components. The extra component is associated with an extra constraint, thus enlarging the gauge group of histories electrodynamics. In this paper we quantise the classical theory developed previously by two methods. Firstly we quantise the reduced classical history space, to obtain a reduced quantum history theory. Secondly we qu...

[Review of: J. Hilton, A. Gosling Alma parens originalis? The receptions of classical literature and thought in Africa, Europe, the United States, and Cuba

NARCIS (Netherlands)

van Weyenberg, A.

2009-01-01

This collection of articles derives in part from the papers presented at the 26th biennial conference of the Classical Association of South Africa held at Durban and Pietermaritzburg in 2005. John Hilton explains in the introduction that the conference's theme, 'The Classical Tradition / Classical

A generalized linear model for estimating spectrotemporal receptive fields from responses to natural sounds.

Directory of Open Access Journals (Sweden)

Ana Calabrese

2011-01-01

Full Text Available In the auditory system, the stimulus-response properties of single neurons are often described in terms of the spectrotemporal receptive field (STRF, a linear kernel relating the spectrogram of the sound stimulus to the instantaneous firing rate of the neuron. Several algorithms have been used to estimate STRFs from responses to natural stimuli; these algorithms differ in their functional models, cost functions, and regularization methods. Here, we characterize the stimulus-response function of auditory neurons using a generalized linear model (GLM. In this model, each cell's input is described by: 1 a stimulus filter (STRF; and 2 a post-spike filter, which captures dependencies on the neuron's spiking history. The output of the model is given by a series of spike trains rather than instantaneous firing rate, allowing the prediction of spike train responses to novel stimuli. We fit the model by maximum penalized likelihood to the spiking activity of zebra finch auditory midbrain neurons in response to conspecific vocalizations (songs and modulation limited (ml noise. We compare this model to normalized reverse correlation (NRC, the traditional method for STRF estimation, in terms of predictive power and the basic tuning properties of the estimated STRFs. We find that a GLM with a sparse prior predicts novel responses to both stimulus classes significantly better than NRC. Importantly, we find that STRFs from the two models derived from the same responses can differ substantially and that GLM STRFs are more consistent between stimulus classes than NRC STRFs. These results suggest that a GLM with a sparse prior provides a more accurate characterization of spectrotemporal tuning than does the NRC method when responses to complex sounds are studied in these neurons.

New mechanism for bubble nucleation: Classical transitions

International Nuclear Information System (INIS)

Easther, Richard; Giblin, John T. Jr; Hui Lam; Lim, Eugene A.

2009-01-01

Given a scalar field with metastable minima, bubbles nucleate quantum mechanically. When bubbles collide, energy stored in the bubble walls is converted into kinetic energy of the field. This kinetic energy can facilitate the classical nucleation of new bubbles in minima that lie below those of the 'parent' bubbles. This process is efficient and classical, and changes the dynamics and statistics of bubble formation in models with multiple vacua, relative to that derived from quantum tunneling.

Adding an extra storey

DEFF Research Database (Denmark)

Engelmark, Jesper; Dahl, Torben; Melgaard, Ebbe

2007-01-01

of them had to be renovated after a shorter period. In stead of just replacing the original roof with a new one, it is now a days rather common to ad an extra storey where that is possible according to local planning. The reason is as a rule based on economical benefits, but very often this extra storey...

THE APPLICABILITY TO THE CLASSICAL POEM OF BEING SCIENTIFICS IN UNDERSTANDING AND EXPLANATION THE TEXT OF THE FORMALISTS AND THE RECEPTIONS BİÇİMCİ VE ALIMLAMACILARIN METNİ ANLAMA VE ANLAMLANDIRMADAKİ BİLİMSELLİKLERİNİN KLÂSİK ŞİİRE UYGULANABİLİRLİĞİ

Directory of Open Access Journals (Sweden)

İlhan GENÇ

2009-09-01

Full Text Available Apart from traditional texts “Form” and reception are considered as important. In this paper these Classical Turkish Literature methods will be discussed. There will be suggestions on the applicabality in this discussion on the theoretical dimension of the subject. Geleneksel metin şerhi dışında modern metotlardan Biçimcilik ve Alımlamacılık önemli sayılmıştır. Makalemizde bu iki metodun Klasik Türk edebiyatı metinlerine uygulanıp uygulanmayacağı tartışılacaktır. Bu tartışmanın teorik boyutuna göre uygulanabilirliği için önerilerde bulunulacaktır.

Effects of Nose Bluntness on Hypersonic Boundary-Layer Receptivity and Stability Over Cones

Science.gov (United States)

Kara, Kursat; Balakumar, Ponnampalam; Kandil, Osama A.

2011-01-01

The receptivity to freestream acoustic disturbances and the stability properties of hypersonic boundary layers are numerically investigated for boundary-layer flows over a 5 straight cone at a freestream Mach number of 6.0. To compute the shock and the interaction of the shock with the instability waves, the Navier-Stokes equations in axisymmetric coordinates were solved. In the governing equations, inviscid and viscous flux vectors are discretized using a fifth-order accurate weighted-essentially-non-oscillatory scheme. A third-order accurate total-variation-diminishing Runge-Kutta scheme is employed for time integration. After the mean flow field is computed, disturbances are introduced at the upstream end of the computational domain. The appearance of instability waves near the nose region and the receptivity of the boundary layer with respect to slow mode acoustic waves are investigated. Computations confirm the stabilizing effect of nose bluntness and the role of the entropy layer in the delay of boundary-layer transition. The current solutions, compared with experimental observations and other computational results, exhibit good agreement.

Divine Love: The Reception of Leda and the Swan Myth in Works by Jewish and Arab Israeli Artists - Contexts and Meanings

Directory of Open Access Journals (Sweden)

Nava Sevilla Sadeh

2014-09-01

Full Text Available The motif of the abduction of a woman is one of the most frequent in Ancient Greek and Roman art. Abductions in mythology are generally portrayed as carried out by a god disguised as a human or an animal, such as Zeus who, in the form of a bull, golden rain or a swan, seduces a beautiful young maiden. These myths have been interpreted from different viewpoints, such as gender, social, political and philosophical. One of the most frequent myths of abduction is that of Leda and the Swan, which appears in both Greek and Roman painting and sculpture. This theme has found many echoes in contemporary Israeli art, and constitutes the case study for this discussion, which belongs to the field of Classical Reception studies. The interpretations of this myth are diverse, ranging from a socio-gender context, to post-colonialism and its relevance to the local situation; to subversives, concerning tradition versus contemporary culture; to emotionality and romantic suffering; and to love as phantasmagoria. These varied interpretations will be examined in the following analysis in light of both ancient concepts and contemporary outlooks, based on literary and philosophical sources.

Are They Listening? Parental Social Coaching and Parenting Emotional Climate Predict Adolescent Receptivity.

Science.gov (United States)

Gregson, Kim D; Erath, Stephen A; Pettit, Gregory S; Tu, Kelly M

2016-12-01

Associations linking parenting emotional climate and quality of parental social coaching with young adolescents' receptivity to parental social coaching were examined (N = 80). Parenting emotional climate was assessed with adolescent-reported parental warmth and hostility. Quality of parental social coaching (i.e., prosocial advice, benign framing) was assessed via parent-report and behavioral observations during a parent-adolescent discussion about negative peer evaluation. An adolescent receptivity latent variable score was derived from observations of adolescents' behavior during the discussion, change in adolescents' peer response plan following the discussion, and adolescent-reported tendency to seek social advice from the parent. Parenting climate moderated associations between coaching and receptivity: Higher quality coaching was associated with greater receptivity in the context of a more positive climate. Analyses suggested a stronger association between coaching and receptivity among younger compared to older adolescents. © 2015 The Authors. Journal of Research on Adolescence © 2015 Society for Research on Adolescence.

Teaching receptive naming of Chinese characters to children with autism by incorporating echolalia.

OpenAIRE

Leung, J P; Wu, K I

1997-01-01

The facilitative effect of incorporating echolalia on teaching receptive naming of Chinese characters to children with autism was assessed. In Experiment 1, echoing the requested character name prior to the receptive naming task facilitated matching a character to its name. In addition, task performance was consistently maintained only when echolalia preceded the receptive manual response. Positive results from generalization tests suggested that learned responses occurred across various nove...

Classical-quantum correspondence in electron-positron pair creation

International Nuclear Information System (INIS)

Chott, N. I.; Su, Q.; Grobe, R.

2007-01-01

We examine the creation of electron-positron pairs in a very strong force field. Using numerical solutions to quantum field theory we calculate the spatial and momentum probability distributions for the created particles. A comparison with classical mechanical phase space calculations suggests that despite the fully relativistic and quantum mechanical nature of the matter creation process, most aspects can be reproduced accurately in terms of classical mechanics

Receptivity to television fast-food restaurant marketing and obesity among U.S. youth.

Science.gov (United States)

McClure, Auden C; Tanski, Susanne E; Gilbert-Diamond, Diane; Adachi-Mejia, Anna M; Li, Zhigang; Li, Zhongze; Sargent, James D

2013-11-01

Advertisement of fast food on TV may contribute to youth obesity. The goal of the study was to use cued recall to determine whether TV fast-food advertising is associated with youth obesity. A national sample of 2541 U.S. youth, aged 15-23 years, were surveyed in 2010-2011; data were analyzed in 2012. Respondents viewed a random subset of 20 advertisement frames (with brand names removed) selected from national TV fast-food restaurant advertisements (n=535) aired in the previous year. Respondents were asked if they had seen the advertisement, if they liked it, and if they could name the brand. A TV fast-food advertising receptivity score (a measure of exposure and response) was assigned; a 1-point increase was equivalent to affirmative responses to all three queries for two separate advertisements. Adjusted odds of obesity (based on self-reported height and weight), given higher TV fast-food advertising receptivity, are reported. The prevalence of overweight and obesity, weighted to the U.S. population, was 20% and 16%, respectively. Obesity, sugar-sweetened beverage consumption, fast-food restaurant visit frequency, weekday TV time, and TV alcohol advertising receptivity were associated with higher TV fast-food advertising receptivity (median=3.3 [interquartile range: 2.2-4.2]). Only household income, TV time, and TV fast-food advertising receptivity retained multivariate associations with obesity. For every 1-point increase in TV fast-food advertising receptivity score, the odds of obesity increased by 19% (OR=1.19, 95% CI=1.01, 1.40). There was no association between receptivity to televised alcohol advertisements or fast-food restaurant visit frequency and obesity. Using a cued-recall assessment, TV fast-food advertising receptivity was found to be associated with youth obesity. © 2013 American Journal of Preventive Medicine.

Receptivity to Television Fast-Food Restaurant Marketing and Obesity Among U.S. Youth

Science.gov (United States)

McClure, Auden C.; Tanski, Susanne E.; Gilbert-Diamond, Diane; Adachi-Mejia, Anna M.; Li, Zhigang; Li, Zhongze; Sargent, James D.

2013-01-01

Background Advertisement of fast food on TV may contribute to youth obesity. Purpose The goal of the study was to use cued recall to determine whether TV fast-food advertising is associated with youth obesity. Methods A national sample of 2541 U.S. youth, aged 15–23 years, were surveyed in 2010–2011; data were analyzed in 2012. Respondents viewed a random subset of 20 advertisement frames (with brand names removed) selected from national TV fast-food restaurant advertisements (n=535) aired in the previous year. Respondents were asked if they had seen the advertisement, if they liked it, and if they could name the brand. A TV fast-food advertising receptivity score (a measure of exposure and response) was assigned; a 1-point increase was equivalent to affirmative responses to all three queries for two separate advertisements. Adjusted odds of obesity (based on self-reported height and weight), given higher TV fast-food advertising receptivity, are reported. Results The prevalence of overweight and obesity, weighted to the U.S. population, was 20% and 16%, respectively. Obesity, sugar-sweetened beverage consumption, fast-food restaurant visit frequency, weekday TV time, and TV alcohol advertising receptivity were associated with higher TV fast-food advertising receptivity (median=3.3 [interquartile range: 2.2–4.2]). Only household income, TV time, and TV fast-food advertising receptivity retained multivariate associations with obesity. For every 1-point increase in TV fast-food advertising receptivity score, the odds of obesity increased by 19% (OR=1.19, 95% CI=1.01, 1.40). There was no association between receptivity to televised alcohol advertisements or fast-food restaurant visit frequency and obesity. Conclusions Using a cued-recall assessment, TV fast-food advertising receptivity was found to be associated with youth obesity. PMID:24139768

Classical dynamics a modern perspective

CERN Document Server

Sudarshan, Ennackal Chandy George

2016-01-01

Classical dynamics is traditionally treated as an early stage in the development of physics, a stage that has long been superseded by more ambitious theories. Here, in this book, classical dynamics is treated as a subject on its own as well as a research frontier. Incorporating insights gained over the past several decades, the essential principles of classical dynamics are presented, while demonstrating that a number of key results originally considered only in the context of quantum theory and particle physics, have their foundations in classical dynamics.Graduate students in physics and practicing physicists will welcome the present approach to classical dynamics that encompasses systems of particles, free and interacting fields, and coupled systems. Lie groups and Lie algebras are incorporated at a basic level and are used in describing space-time symmetry groups. There is an extensive discussion on constrained systems, Dirac brackets and their geometrical interpretation. The Lie-algebraic description of ...

A semi-classical analysis of Dirac fermions in 2+1 dimensions

International Nuclear Information System (INIS)

Maiti, Moitri; Shankar, R

2012-01-01

We investigate the semi-classical dynamics of massless Dirac fermions in 2+1 dimensions in the presence of external electromagnetic fields. By generalizing the α matrices by two generators of the SU(2) group in the (2S + 1)-dimensional representation and doing a certain scaling, we formulate an S → ∞ limit where the orbital and the spinor degrees become classical. We solve for the classical trajectories for a free particle on a cylinder and a particle in a constant magnetic field. We compare the semi-classical spectrum, obtained by Bohr–Sommerfeld quantization with the exact quantum spectrum for low values of S. For the free particle, the semi-classical spectrum is exact. For the particle in a constant magnetic field, the semi-classical spectrum reproduces all the qualitative features of the exact quantum spectrum at all S. The quantitative fit for S = 1/2 is reasonably good. (paper)

Learning to reach by reinforcement learning using a receptive field based function approximation approach with continuous actions.

Science.gov (United States)

Tamosiunaite, Minija; Asfour, Tamim; Wörgötter, Florentin

2009-03-01

Reinforcement learning methods can be used in robotics applications especially for specific target-oriented problems, for example the reward-based recalibration of goal directed actions. To this end still relatively large and continuous state-action spaces need to be efficiently handled. The goal of this paper is, thus, to develop a novel, rather simple method which uses reinforcement learning with function approximation in conjunction with different reward-strategies for solving such problems. For the testing of our method, we use a four degree-of-freedom reaching problem in 3D-space simulated by a two-joint robot arm system with two DOF each. Function approximation is based on 4D, overlapping kernels (receptive fields) and the state-action space contains about 10,000 of these. Different types of reward structures are being compared, for example, reward-on- touching-only against reward-on-approach. Furthermore, forbidden joint configurations are punished. A continuous action space is used. In spite of a rather large number of states and the continuous action space these reward/punishment strategies allow the system to find a good solution usually within about 20 trials. The efficiency of our method demonstrated in this test scenario suggests that it might be possible to use it on a real robot for problems where mixed rewards can be defined in situations where other types of learning might be difficult.

Particle Phenomenology of Compact Extra Dimensions

International Nuclear Information System (INIS)

Melbeus, Henrik

2012-01-01

This thesis is an investigation of the subject of extra dimensions in particle physics. In recent years, there has been a large interest in this subject. In particular, a number of models have been suggested that provide solutions to some of the problem with the current Standard Model of particle physics. These models typically give rise to experimental signatures around the TeV energy scale, which means that they could be tested in the next generation of high-energy experiments, such as the LHC. Among the most important of these models are the universal extra dimensions model, the large extra dimensions model by Arkani-Hamed, Dimopolous, and Dvali, and models where right-handed neutrinos propagate in the extra dimensions. In the thesis, we study phenomenological aspects of these models, or simple modifications of them. In particular, we focus on Kaluza-Klein dark matter in universal extra dimensions models, different aspects of neutrino physics in higher dimensions, and collider phenomenology of extra dimensions. In addition, we consider consequences of the enhanced renormalization group running of physical parameters in higher-dimensional models

Mathematical methods of classical physics

CERN Document Server

Cortés, Vicente

2017-01-01

This short primer, geared towards students with a strong interest in mathematically rigorous approaches, introduces the essentials of classical physics, briefly points out its place in the history of physics and its relation to modern physics, and explains what benefits can be gained from a mathematical perspective. As a starting point, Newtonian mechanics is introduced and its limitations are discussed. This leads to and motivates the study of different formulations of classical mechanics, such as Lagrangian and Hamiltonian mechanics, which are the subjects of later chapters. In the second part, a chapter on classical field theories introduces more advanced material. Numerous exercises are collected in the appendix.

P3-9: Roles of Subthreshold LFP Induced by Receptive Field Surround for Response Modulation in Monkey V1

Directory of Open Access Journals (Sweden)

Kayeon Kim

2012-10-01

Full Text Available A focal stimulus outside the receptive field robustly induces LFP change, while the same stimulus evokes no spike activity. We determined how this subthreshold LFP change interacted with spike response to the RF stimulus. Specifically, we sequentially presented two identical Gabor stimuli with a variable stimulus onset asynchrony (SOA; the first one (S1 was presented outside RF inducing a subthreshold LFP change, and the second one (S2 was subsequently presented within RF generating a spiking response. This enabled us to manipulate the temporal relation between subthreshold LFP and evoked spike activity and to determine whether subthreshold LFP contributed to modulation of spike activity in a SOA-dependent manner. We found that the subthreshold LFP propagated a considerably long distance, estimated to be more than 10 mm of cortical distance. The cross-correlation between the time course of subthreshold LFP and the pattern of SOA-dependency of spike activity was significant. These results indicate that signal integration is farther beyond the RF than previously estimated based on spike-triggered average, and suggest that subthreshold LFP modulate spike activity in a SOA-dependent manner.

Effect of leading-edge geometry on boundary-layer receptivity to freestream sound

Science.gov (United States)

Lin, Nay; Reed, Helen L.; Saric, W. S.

1991-01-01

The receptivity to freestream sound of the laminar boundary layer over a semi-infinite flat plate with an elliptic leading edge is simulated numerically. The incompressible flow past the flat plate is computed by solving the full Navier-Stokes equations in general curvilinear coordinates. A finite-difference method which is second-order accurate in space and time is used. Spatial and temporal developments of the Tollmien-Schlichting wave in the boundary layer, due to small-amplitude time-harmonic oscillations of the freestream velocity that closely simulate a sound wave travelling parallel to the plate, are observed. The effect of leading-edge curvature is studied by varying the aspect ratio of the ellipse. The boundary layer over the flat plate with a sharper leading edge is found to be less receptive. The relative contribution of the discontinuity in curvature at the ellipse-flat-plate juncture to receptivity is investigated by smoothing the juncture with a polynomial. Continuous curvature leads to less receptivity. A new geometry of the leading edge, a modified super ellipse, which provides continuous curvature at the juncture with the flat plate, is used to study the effect of continuous curvature and inherent pressure gradient on receptivity.

Classic Problems of Probability

CERN Document Server

Gorroochurn, Prakash

2012-01-01

"A great book, one that I will certainly add to my personal library."—Paul J. Nahin, Professor Emeritus of Electrical Engineering, University of New Hampshire Classic Problems of Probability presents a lively account of the most intriguing aspects of statistics. The book features a large collection of more than thirty classic probability problems which have been carefully selected for their interesting history, the way they have shaped the field, and their counterintuitive nature. From Cardano's 1564 Games of Chance to Jacob Bernoulli's 1713 Golden Theorem to Parrondo's 1996 Perplexin

Three-dimensional stability, receptivity and sensitivity of non-Newtonian flows inside open cavities

International Nuclear Information System (INIS)

Citro, Vincenzo; Giannetti, Flavio; Pralits, Jan O

2015-01-01

We investigate the stability properties of flows over an open square cavity for fluids with shear-dependent viscosity. Analysis is carried out in context of the linear theory using a normal-mode decomposition. The incompressible Cauchy equations, with a Carreau viscosity model, are discretized with a finite-element method. The characteristics of direct and adjoint eigenmodes are analyzed and discussed in order to understand the receptivity features of the flow. Furthermore, we identify the regions of the flow that are more sensitive to spatially localized feedback by building a spatial map obtained from the product between the direct and adjoint eigenfunctions. Analysis shows that the first global linear instability of the steady flow is a steady or unsteady three-dimensionl bifurcation depending on the value of the power-law index n. The instability mechanism is always located inside the cavity and the linear stability results suggest a strong connection with the classical lid-driven cavity problem. (paper)

Theory of motion for monopole-dipole singularities of classical Yang-Mills-Higgs fields. I. Laws of motion

International Nuclear Information System (INIS)

Drechsler, W.; Havas, P.; Rosenblum, A.

1984-01-01

In two recent papers, the general form of the laws of motion for point particles which are multipole sources of the classical coupled Yang-Mills-Higgs fields was determined by Havas, and for the special case of monopole singularities of a Yang-Mills field an iteration procedure was developed by Drechsler and Rosenblum to obtain the equations of motion of mass points, i.e., the laws of motion including the explicit form of the fields of all interacting particles. In this paper we give a detailed derivation of the laws of motion of monopole-dipole singularities of the coupled Yang-Mills-Higgs fields for point particles with mass and spin, following a procedure first applied by Mathisson and developed by Havas. To obtain the equations of motion, a systematic approximation method is developed in the following paper for the solution of the nonlinear field equations and determination of the fields entering the laws of motion found here to any given order in the coupling constant g

Receptivity and Forced Response to Acoustic Disturbances in High-Speed Boundary Layers

Science.gov (United States)

Balakumar, P.; King, Rudolph A.; Chou, Amanda; Owens, Lewis R.; Kegerise, Michael A.

2016-01-01

Supersonic boundary-layer receptivity to freestream acoustic disturbances is investigated by solving the Navier-Stokes equations for Mach 3.5 flow over a sharp flat plate and a 7-deg half-angle cone. The freestream disturbances are generated from a wavy wall placed at the nozzle wall. The freestream acoustic disturbances radiated by the wavy wall are obtained by solving the linearized Euler equations. The results for the flat plate show that instability modes are generated at all the incident angles ranging from zero to highly oblique. However, the receptivity coefficient decreases by about 20 times when the incident angle increases from zero to a highly oblique angle of 68 degrees. The results for the cone show that no instability modes are generated when the acoustic disturbances impinge the cone obliquely. The results show that the perturbations generated inside the boundary layer by the acoustic disturbances are the response of the boundary layer to the external forcing. The amplitude of the forced disturbances inside the boundary layer are about 2.5 times larger than the incoming field for zero azimuthal wavenumber and they are about 1.5 times for large azimuthal wavenumbers.

A classical model for the electron

International Nuclear Information System (INIS)

Visser, M.

1989-01-01

The construction of classical and semi-classical models for the electron has had a long and distinguished history. Such models are useful more for what they teach us about field theory than what they teach us about the electron. In this Letter I exhibit a classical model of the electron consisting of ordinary electromagnetism coupled with a self-interacting version of Newtonian gravity. The gravitational binding energy of the system balances the electrostatic energy in such a manner that the total rest mass of the electron is finite. (orig.)

Supersymmetry breaking with extra dimensions

International Nuclear Information System (INIS)

Zwirner, Fabio

2004-01-01

This talk reviews some aspects of supersymmetry breaking in the presence of extra dimensions. The first part is a general introduction, recalling the motivations for supersymmetry and extra dimensions, as well as some unsolved problems of four-dimensional models of supersymmetry breaking. The central part is a more focused introduction to a mechanism for (super)symmetry breaking, proposed first by Scherk and Schwarz, where extra dimensions play a crucial role. The last part is devoted to the description of some recent results and of some open problems. (author)

From conciliar ecumenism to transformative receptive ecumenism

Directory of Open Access Journals (Sweden)

Mary-Anne Plaatjies van Huffel

2017-09-01

Full Text Available This article attends to ecumenicity as the second reformation. The ecumenical organisations and agencies hugely influenced the theological praxis and reflection of the church during the past century. The First World Council of Churches (WCC Assembly in Amsterdam, the Netherlands, has been described as the most significant event in church history since the Reformation during the past decade. We saw the emergence of two initiatives that are going to influence ecumenical theology and practice in future, namely the Receptive Ecumenism and Catholic Learning research project, based in Durham, United Kingdom, and the International Theological Colloquium for Transformative Ecumenism of the WCC. Both initiatives constitute a fresh approach in methodology to ecumenical theology and practice. Attention will be given in this article to conciliar ecumenism, receptive ecumenism, transformative ecumenism and its implications for the development of an African transformative receptive ecumenism. In doing so, we should take cognisance of what Küng says about a confessionalist ghetto mentality: ‘We must avoid a confessionalistic ghetto mentality. Instead we should espouse an ecumenical vision that takes into consideration the world religions as well as contemporary ideologies: as much tolerance as possible toward those things outside the Church, toward the religious in general, and the human in general, and the development of that which is specifically Christian belong together!’

Classical behavior of few-electron parabolic quantum dots

International Nuclear Information System (INIS)

Ciftja, O.

2009-01-01

Quantum dots are intricate and fascinating systems to study novel phenomena of great theoretical and practical interest because low dimensionality coupled with the interplay between strong correlations, quantum confinement and magnetic field creates unique conditions for emergence of fundamentally new physics. In this work we consider two-dimensional semiconductor quantum dot systems consisting of few interacting electrons confined in an isotropic parabolic potential. We study the many-electron quantum ground state properties of such systems in presence of a perpendicular magnetic field as the number of electrons is varied using exact numerical diagonalizations and other approaches. The results derived from the calculations of the quantum model are then compared to corresponding results for a classical model of parabolically confined point charges who interact with a Coulomb potential. We find that, for a wide range of parameters and magnetic fields considered in this work, the quantum ground state energy is very close to the classical energy of the most stable classical configuration under the condition that the classical energy is properly adjusted to incorporate the quantum zero point motion.

47 CFR 73.825 - Protection to reception of TV channel 6.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 4 2010-10-01 2010-10-01 false Protection to reception of TV channel 6. 73.825... RADIO BROADCAST SERVICES Low Power FM Broadcast Stations (LPFM) § 73.825 Protection to reception of TV... separation distances in the following table are met with respect to all full power TV Channel 6 stations. FM...

Efficiency of an automated reception and turnaround time management system for the phlebotomy room.

Science.gov (United States)

Yun, Soon Gyu; Shin, Jeong Won; Park, Eun Su; Bang, Hae In; Kang, Jung Gu

2016-01-01

Recent advances in laboratory information systems have largely been focused on automation. However, the phlebotomy services have not been completely automated. To address this issue, we introduced an automated reception and turnaround time (TAT) management system, for the first time in Korea, whereby the patient's information is transmitted directly to the actual phlebotomy site and the TAT for each phlebotomy step can be monitored at a glance. The GNT5 system (Energium Co., Ltd., Korea) was installed in June 2013. The automated reception and TAT management system has been in operation since February 2014. Integration of the automated reception machine with the GNT5 allowed for direct transmission of laboratory order information to the GNT5 without involving any manual reception step. We used the mean TAT from reception to actual phlebotomy as the parameter for evaluating the efficiency of our system. Mean TAT decreased from 5:45 min to 2:42 min after operationalization of the system. The mean number of patients in queue decreased from 2.9 to 1.0. Further, the number of cases taking more than five minutes from reception to phlebotomy, defined as the defect rate, decreased from 20.1% to 9.7%. The use of automated reception and TAT management system was associated with a decrease of overall TAT and an improved workflow at the phlebotomy room.

Cat retinal ganglion cell receptive-field alterations after 6-hydroxydopamine induced dopaminergic amacrine cell lesions

International Nuclear Information System (INIS)

Maguire, G.W.; Smith, E.L. III

1985-01-01

Optic tract single-unit recordings were used to study ganglion cell response functions of the intact cat eye after 6-hydroxydopamine (6-OHDA) lesioning of the dopaminergic amacrine cell (AC) population of the inner retina. The impairment of the dopaminergic AC was verified by high pressure-liquid chromatography with electrochemical detection of endogenous dopamine content and by [ 3 H]dopamine high-affinity uptake; the dopaminergic ACs of the treated eyes demonstrated reduced endogenous dopamine content and reduced [ 3 H]dopamine uptake compared with that of their matched controls. Normal appearing [ 3 H]GABA and [ 3 H]-glycine uptake in the treated retinas suggests the absence of any nonspecific action of the 6-OHDA on the neural retina. The impairment of the dopaminergic AC population was found to alter a number of response properties in off-center ganglion cells, but this impairment had only a modest effect on the on-center cells. An abnormally high proportion of the off-center ganglion cells in the 6-OHDA treated eyes possessed nonlinear, Y-type receptive fields. These cells also possessed shift-responses of greater than normal amplitude, altered intensity-response functions, reduced maintained activities, and more transient center responses. Of the on-center type cells, only the Y-type on-center cells were affected by 6-OHDA, possessing higher than normal maintained activities and altered intensity-response functions. The on-center X-cells were unaffected by 6-OHDA treatment. The dopaminergic AC of the photopically adapted cat retina therefore modulates a number of ganglion cell response properties and within the limits of this study is most prominent in off-center ganglion cell circuitry

Housing Service: Receptions of the CERN and St.-Genis-Pouilly Hostels

CERN Multimedia

2005-01-01

Opening times Please note the new and definitive opening times of the Receptions of the hostels on the Swiss site of CERN and in St. Genis : CERN hostels St.-Genis hostel from Monday to Friday 7:30 - 19:30 8:00 - 12:00 16:00 - 19:00 Saturday 9:00 - 13:00 closed Sunday 9:00 - 13:00 closed Outside these times keys to rooms reserved in advance can be obtained from the guards on duty at the main entrance to the Meyrin, Switzerland, CERN site (Gate B), where they are deposited some fifteen minutes after the closure of the Reception. As for the St. Genis hostel, for arrivals on Saturdays and Sundays, the keys are deposited with the guards in advance on the preceding Friday evening. Reminder : reservations, whether for the CERN hostels or the St. Genis hostel, are available through the Reception of the CERN hostels. Once the reservation has been confirmed, in the case of St. Genis, all other business, including payment, is dealt with by the St. Genis hostel reception. As far as possible, all r...

The Critical Reception of Lewis Nordan

DEFF Research Database (Denmark)

Bjerre, Thomas Ærvold

2010-01-01

The essay covers the critical reception of Mississippi-writer Lewis Nordan from his debut in 1983 to the boost in scholarly attention in the new millennium. The essay covers newspaper reviews but pays particular attention to the many academic essays that have placed Nordan as a writer...

The reception of the models of the New School in the Spanish manualistic of the early 20th century

Directory of Open Access Journals (Sweden)

Agustín ESCOLANO BENITO

2013-11-01

Full Text Available This paper examines certain aspects related to the reception of the patterns of the New Education in the Spanish textbooks of the first third of the 20th century. This appropiation of the renewing pedagogical models by writers of didac- tic texts is also related to the processes of school modernisation during the period in Spanish and supose a mode of metamorphosis undergone by the principles of the renewed education on being transferred to the world of the prevailing educational practice. This influence consisted of the changes which affected the classical textbooks and in the appearance of new types of manuals which correspond to specific models and give rise to new textual forms.

Polarizable Force Field for DNA Based on the Classical Drude Oscillator: I. Refinement Using Quantum Mechanical Base Stacking and Conformational Energetics.

Science.gov (United States)

Lemkul, Justin A; MacKerell, Alexander D

2017-05-09

Empirical force fields seek to relate the configuration of a set of atoms to its energy, thus yielding the forces governing its dynamics, using classical physics rather than more expensive quantum mechanical calculations that are computationally intractable for large systems. Most force fields used to simulate biomolecular systems use fixed atomic partial charges, neglecting the influence of electronic polarization, instead making use of a mean-field approximation that may not be transferable across environments. Recent hardware and software developments make polarizable simulations feasible, and to this end, polarizable force fields represent the next generation of molecular dynamics simulation technology. In this work, we describe the refinement of a polarizable force field for DNA based on the classical Drude oscillator model by targeting quantum mechanical interaction energies and conformational energy profiles of model compounds necessary to build a complete DNA force field. The parametrization strategy employed in the present work seeks to correct weak base stacking in A- and B-DNA and the unwinding of Z-DNA observed in the previous version of the force field, called Drude-2013. Refinement of base nonbonded terms and reparametrization of dihedral terms in the glycosidic linkage, deoxyribofuranose rings, and important backbone torsions resulted in improved agreement with quantum mechanical potential energy surfaces. Notably, we expand on previous efforts by explicitly including Z-DNA conformational energetics in the refinement.

Quantum dynamics in open quantum-classical systems.

Science.gov (United States)

Kapral, Raymond

2015-02-25

Often quantum systems are not isolated and interactions with their environments must be taken into account. In such open quantum systems these environmental interactions can lead to decoherence and dissipation, which have a marked influence on the properties of the quantum system. In many instances the environment is well-approximated by classical mechanics, so that one is led to consider the dynamics of open quantum-classical systems. Since a full quantum dynamical description of large many-body systems is not currently feasible, mixed quantum-classical methods can provide accurate and computationally tractable ways to follow the dynamics of both the system and its environment. This review focuses on quantum-classical Liouville dynamics, one of several quantum-classical descriptions, and discusses the problems that arise when one attempts to combine quantum and classical mechanics, coherence and decoherence in quantum-classical systems, nonadiabatic dynamics, surface-hopping and mean-field theories and their relation to quantum-classical Liouville dynamics, as well as methods for simulating the dynamics.

Nonabelian noncommutative gauge theory via noncommutative extra dimensions

Energy Technology Data Exchange (ETDEWEB)

Jurco, Branislav E-mail: jurco@theorie.physik.uni-muenchen.de; Schupp, Peter E-mail: schupp@theorie.physik.uni-muenchen.de; Wess, Julius E-mail: wess@theorie.physik.uni-muenchen.de

2001-06-18

The concept of covariant coordinates on noncommutative spaces leads directly to gauge theories with generalized noncommutative gauge fields of the type that arises in string theory with background B-fields. The theory is naturally expressed in terms of cochains in an appropriate cohomology; we discuss how it fits into the framework of projective modules. The equivalence of star products that arise from the background field with and without fluctuations and Kontsevich's formality theorem allow an explicitly construction of a map that relates ordinary gauge theory and noncommutative gauge theory (Seiberg-Witten map). As application we show the exact equality of the Dirac-Born-Infeld action with B-field in the commutative setting and its semi-noncommutative cousin in the intermediate picture. Using noncommutative extra dimensions the construction is extended to noncommutative nonabelian gauge theory for arbitrary gauge groups; an explicit map between abelian and nonabelian gauge fields is given. All constructions are also valid for non-constant B-field, Poisson structure and metric.

Nonabelian noncommutative gauge theory via noncommutative extra dimensions

International Nuclear Information System (INIS)

Jurco, Branislav; Schupp, Peter; Wess, Julius

2001-01-01

The concept of covariant coordinates on noncommutative spaces leads directly to gauge theories with generalized noncommutative gauge fields of the type that arises in string theory with background B-fields. The theory is naturally expressed in terms of cochains in an appropriate cohomology; we discuss how it fits into the framework of projective modules. The equivalence of star products that arise from the background field with and without fluctuations and Kontsevich's formality theorem allow an explicitly construction of a map that relates ordinary gauge theory and noncommutative gauge theory (Seiberg-Witten map). As application we show the exact equality of the Dirac-Born-Infeld action with B-field in the commutative setting and its semi-noncommutative cousin in the intermediate picture. Using noncommutative extra dimensions the construction is extended to noncommutative nonabelian gauge theory for arbitrary gauge groups; an explicit map between abelian and nonabelian gauge fields is given. All constructions are also valid for non-constant B-field, Poisson structure and metric

Characteristics and prediction of sound level in extra-large spaces

OpenAIRE

Wang, C.; Ma, H.; Wu, Y.; Kang, J.

2018-01-01

This paper aims to examine sound fields in extra-large spaces, which are defined in this paper as spaces used by people, with a volume approximately larger than 125,000m 3 and absorption coefficient less than 0.7. In such spaces inhomogeneous reverberant energy caused by uneven early reflections with increasing volume has a significant effect on sound fields. Measurements were conducted in four spaces to examine the attenuation of the total and reverberant energy with increasing source-receiv...

Dynamics of unitarization by classicalization

International Nuclear Information System (INIS)

Dvali, Gia; Pirtskhalava, David

2011-01-01

We study dynamics of the classicalization phenomenon suggested in G. Dvali et al. , according to which a class of non-renormalizable theories self-unitarizes at very high-energies via creation of classical configurations (classicalons). We study this phenomenon in an explicit model of derivatively-self-coupled scalar that serves as a prototype for a Nambu-Goldstone-Stueckelberg field. We prepare the initial state in form of a collapsing wave-packet of a small occupation number but of very high energy, and observe that the classical configuration indeed develops. Our results confirm the previous estimates, showing that because of self-sourcing the wave-packet forms a classicalon configuration with radius that increases with center of mass energy. Thus, classicalization takes place before the waves get any chance of probing short-distances. The self-sourcing by energy is the crucial point, which makes classicalization phenomenon different from the ordinary dispersion of the wave-packets in other interacting theories. Thanks to this, unlike solitons or other non-perturbative objects, the production of classicalons is not only unsuppressed, but in fact dominates the high-energy scattering. In order to make the difference between classicalizing and non-classicalizing theories clear, we use a language in which the scattering cross section in a generic theory can be universally understood as a geometric cross section set by a classical radius down to which waves can propagate freely, before being scattered. We then show, that in non-classicalizing examples this radius shrinks with increasing energy and becomes microscopic, whereas in classicalizing theories expands and becomes macroscopic. We study analogous scattering in a Galileon system and discover that classicalization also takes place there, although somewhat differently. We thus observe, that classicalization is source-sensitive and that Goldstones pass the first test.

Design of signal reception and processing system of embedded ultrasonic endoscope

Science.gov (United States)

Li, Ming; Yu, Feng; Zhang, Ruiqiang; Li, Yan; Chen, Xiaodong; Yu, Daoyin

2009-11-01

Embedded Ultrasonic Endoscope, based on embedded microprocessor and embedded real-time operating system, sends a micro ultrasonic probe into coelom through the biopsy channel of the Electronic Endoscope to get the fault histology features of digestive organs by rotary scanning, and acquires the pictures of the alimentary canal mucosal surface. At the same time, ultrasonic signals are processed by signal reception and processing system, forming images of the full histology of the digestive organs. Signal Reception and Processing System is an important component of Embedded Ultrasonic Endoscope. However, the traditional design, using multi-level amplifiers and special digital processing circuits to implement signal reception and processing, is no longer satisfying the standards of high-performance, miniaturization and low power requirements that embedded system requires, and as a result of the high noise that multi-level amplifier brought, the extraction of small signal becomes hard. Therefore, this paper presents a method of signal reception and processing based on double variable gain amplifier and FPGA, increasing the flexibility and dynamic range of the Signal Reception and Processing System, improving system noise level, and reducing power consumption. Finally, we set up the embedded experiment system, using a transducer with the center frequency of 8MHz to scan membrane samples, and display the image of ultrasonic echo reflected by each layer of membrane, with a frame rate of 5Hz, verifying the correctness of the system.

Classical Dimensional Transmutation and Confinement

CERN Document Server

Dvali, Gia; Mukhanov, Slava

2011-01-01

We observe that probing certain classical field theories by external sources uncovers the underlying renormalization group structure, including the phenomenon of dimensional transmutation, at purely-classical level. We perform this study on an example of $\\lambda\\phi^{4}$ theory and unravel asymptotic freedom and triviality for negative and positives signs of $\\lambda$ respectively. We derive exact classical $\\beta$ function equation. Solving this equation we find that an isolated source has an infinite energy and therefore cannot exist as an asymptotic state. On the other hand a dipole, built out of two opposite charges, has finite positive energy. At large separation the interaction potential between these two charges grows indefinitely as a distance in power one third.

Difficulties Using Standardized Tests to Identify the Receptive Expressive Gap in Bilingual Children's Vocabularies.

Science.gov (United States)

Gibson, Todd A; Oller, D Kimbrough; Jarmulowicz, Linda

2018-03-01

Receptive standardized vocabulary scores have been found to be much higher than expressive standardized vocabulary scores in children with Spanish as L1, learning L2 (English) in school (Gibson et al., 2012). Here we present evidence suggesting the receptive-expressive gap may be harder to evaluate than previously thought because widely-used standardized tests may not offer comparable normed scores. Furthermore monolingual Spanish-speaking children tested in Mexico and monolingual English-speaking children in the US showed other, yet different statistically significant discrepancies between receptive and expressive scores. Results suggest comparisons across widely used standardized tests in attempts to assess a receptive-expressive gap are precarious.

PREFACE: IARD 2012: 8th Biennial Conference on Classical and Quantum Relativistic Dynamics of Particles and Fields

Science.gov (United States)

Horwitz, L. P.; Land, Martin C.; Gill, Tepper; Lusanna, Luca; Salucci, Paolo

2013-04-01

developments in cosmology and astrophysics, the geometry of spacetime, including the possible presence of extra dimensions, and in the dynamics of systems described in the framework of general relativity. There have been recent developments as well in the foundations of relativity, and in the understanding of electrodynamics in the framework of relativistic quantum theory. There is a study of relativistic quantum mechanics in the rest frame instant form of dynamics, and an analysis of the Laplace-Runge-Lenz symmetry in relativistic dynamics reported here, as well as a discussion of the quantization of massless fields of any spin. Results are reported on the existence and definition of a covariant Berry phase associated with a perturbed covariant harmonic oscillator. A generalization of Stueckelberg's original classical and quantum model for pair production is found to provide a simple framework for the phenomenon of neutrino oscillation, which, along with recently published work on the spin of a system of relativistic particles, appears to provide a simple mechanism for CP violation in the presence of nonabelian gauge fields that seems applicable to the K, B and D meson systems as well, from the point of view of their inner quark structure. New functional methods applicable to both classical and quantum relativistic systems are reported here, and a deep mathematical and philosophical discussion is given on a unified view of nonlinear systems in many areas, including that of perception. We thank the Scientific Advisory Committee for their invaluable guidance and advice: Stephen Adler(Institute for Advanced Study) Itzhak Bars (University of Southern California) Gordon Baym (University of Illinois) Jacob Bekenstein (Hebrew University) Fred Cooper (Los Alamos National Laboratory) Bei-Lok Hu (University of Maryland) Werner Israel (University of Victoria) E V Shuryak (Brookhaven National Laboratory) L S Shulman (Clarkson University) William Unruh (University of British Columbia

Limits on the size of extra-dimensions

International Nuclear Information System (INIS)

Antoniadis, I.

2001-01-01

The authors present a summary of the present status of limits on the following scales of new physics: extra-dimensions and string-like sub-structure of matter. The use of compactification is an elegant way to hide extra-dimensions because some of the quantum numbers and interactions of the elementary particles could be accounted to by the topological and geometrical properties of the internal space. Recent progress made in string theory implies that both the string and compactification scales can be made arbitrarily low. Lowering the string scale, one increases the strength of higher (non-renormalizable) operators leading to the possibility of inducing exotic processes at experimentally excluded rates. Although an explicit string realization of the scenario is necessary in order to have a satisfactorily solution, at the effective field theory level many discrete or global symmetries can be displayed that forbid these operators. There are some processes for which there is only one dimension-eight operator allowed, an example is ff-bar → γγ. Useful information could be deduced from the study of such processes through collider experiments. (A.C.)

Effects of Humor Production, Humor Receptivity, and Physical Attractiveness on Partner Desirability

Directory of Open Access Journals (Sweden)

Michelle Tornquist

2015-10-01

Full Text Available This study examined women’s and men’s preferences for humor production and humor receptivity in long-term and short-term relationships, and how these factors interact with physical attractiveness to influence desirability. Undergraduates viewed photographs of the opposite sex individuals who were high or low in physical attractiveness, along with vignettes varying in humor production and receptivity. Participants rated physical attractiveness and desirability for long-term and short-term relationships. The main findings were that individuals desired partners who were high in humor production and receptivity, though the effects were particularly pronounced for women judging long-term relationships. Moreover, humor production was more important than receptivity for women’s ratings of male desirability. Notably, we also found that ratings of physical attractiveness were influenced by the humor conditions. These results are discussed in terms of the fitness indicator, interest indicator, and encryption hypotheses of the evolutionary functions of humor.

Classical Causal Models for Bell and Kochen-Specker Inequality Violations Require Fine-Tuning

Directory of Open Access Journals (Sweden)

Eric G. Cavalcanti

2018-04-01

Full Text Available Nonlocality and contextuality are at the root of conceptual puzzles in quantum mechanics, and they are key resources for quantum advantage in information-processing tasks. Bell nonlocality is best understood as the incompatibility between quantum correlations and the classical theory of causality, applied to relativistic causal structure. Contextuality, on the other hand, is on a more controversial foundation. In this work, I provide a common conceptual ground between nonlocality and contextuality as violations of classical causality. First, I show that Bell inequalities can be derived solely from the assumptions of no signaling and no fine-tuning of the causal model. This removes two extra assumptions from a recent result from Wood and Spekkens and, remarkably, does not require any assumption related to independence of measurement settings—unlike all other derivations of Bell inequalities. I then introduce a formalism to represent contextuality scenarios within causal models and show that all classical causal models for violations of a Kochen-Specker inequality require fine-tuning. Thus, the quantum violation of classical causality goes beyond the case of spacelike-separated systems and already manifests in scenarios involving single systems.

Hebbian learning in a model with dynamic rate-coded neurons: an alternative to the generative model approach for learning receptive fields from natural scenes.

Science.gov (United States)

Hamker, Fred H; Wiltschut, Jan

2007-09-01

Most computational models of coding are based on a generative model according to which the feedback signal aims to reconstruct the visual scene as close as possible. We here explore an alternative model of feedback. It is derived from studies of attention and thus, probably more flexible with respect to attentive processing in higher brain areas. According to this model, feedback implements a gain increase of the feedforward signal. We use a dynamic model with presynaptic inhibition and Hebbian learning to simultaneously learn feedforward and feedback weights. The weights converge to localized, oriented, and bandpass filters similar as the ones found in V1. Due to presynaptic inhibition the model predicts the organization of receptive fields within the feedforward pathway, whereas feedback primarily serves to tune early visual processing according to the needs of the task.

More than Decadence - Johannes Jørgensen's early reception of Arthur Schopenhauer

DEFF Research Database (Denmark)

Nord, Johan Christian

Fremmedsproglig forskningsformidling af hovedpunkterne i artiklen "En Poet og en Religionsstifter, med hvem jeg er enig i næsten alle Ting" Indledende betragtninger over Johannes Jørgensens Schopenhauer-reception.......Fremmedsproglig forskningsformidling af hovedpunkterne i artiklen "En Poet og en Religionsstifter, med hvem jeg er enig i næsten alle Ting" Indledende betragtninger over Johannes Jørgensens Schopenhauer-reception....

Fundamental and composite scalars from extra dimensions

International Nuclear Information System (INIS)

Aranda, Alfredo; Diaz-Cruz, J.L.; Hernandez-Sanchez, J.; Noriega-Papaqui, R.

2007-01-01

We discuss a scenario consisting of an effective 4D theory containing fundamental and composite fields. The strong dynamics sector responsible for the compositeness is assumed to be of extra dimensional origin. In the 4D effective theory the SM fermion and gauge fields are taken as fundamental fields. The scalar sector of the theory resembles a bosonic topcolor in the sense there are two scalar Higgs fields, a composite scalar field and a fundamental gauge-Higgs unification scalar. A detailed analysis of the scalar spectrum is presented in order to explore the parameter space consistent with experiment. It is found that, under the model assumptions, the acceptable parameter space is quite constrained. As a part of our phenomenological study of the model, we evaluate the branching ratio of the lightest Higgs boson and find that our model predicts a large FCNC mode h→tc, which can be as large as O(10 -3 ). Similarly, a large BR for the top FCNC decay is obtained, namely BR(t→c+H)≅10 -4

Phenomenology of symmetry breaking from extra dimensions

International Nuclear Information System (INIS)

Alfaro, Jorge; Broncano, Alicia; Belen Gavela, Maria; Rigolin, Stefano; Salvatori, Matteo

2007-01-01

Motivated by the electroweak hierarchy problem, we consider theories with two extra dimensions in which the four-dimensional scalar fields are components of gauge boson in full space. We explore the Nielsen-Olesen instability for SU(N) on a torus, in the presence of a magnetic background. A field theory approach is developed, computing explicitly the minimum of the complete effective potential, including tri-linear and quartic couplings and determining the symmetries of the stable vacua. We also develop appropriate gauge-fixing terms when both Kaluza-Klein and Landau levels are present and interacting, discussing the interplay between the possible six and four dimensional choices. The equivalence between coordinate dependent and constant Scherk-Schwarz boundary conditions - associated to either continuous or discrete Wilson lines - is analyzed

Genome-Wide Association Study of Receptive Language Ability of 12-Year-Olds

Science.gov (United States)

Harlaar, Nicole; Meaburn, Emma L.; Hayiou-Thomas, Marianna E.; Davis, Oliver S. P.; Docherty, Sophia; Hanscombe, Ken B.; Haworth, Claire M. A.; Price, Thomas S.; Trzaskowski, Maciej; Dale, Philip S.; Plomin, Robert

2014-01-01

Purpose: Researchers have previously shown that individual differences in measures of receptive language ability at age 12 are highly heritable. In the current study, the authors attempted to identify some of the genes responsible for the heritability of receptive language ability using a "genome-wide association" approach. Method: The…

Quantum and classical dissipation of charged particles

Energy Technology Data Exchange (ETDEWEB)

Ibarra-Sierra, V.G. [Departamento de Física, Universidad Autónoma Metropolitana at Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 México D.F. (Mexico); Anzaldo-Meneses, A.; Cardoso, J.L.; Hernández-Saldaña, H. [Área de Física Teórica y Materia Condensada, Universidad Autónoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 México D.F. (Mexico); Kunold, A., E-mail: akb@correo.azc.uam.mx [Área de Física Teórica y Materia Condensada, Universidad Autónoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 México D.F. (Mexico); Roa-Neri, J.A.E. [Área de Física Teórica y Materia Condensada, Universidad Autónoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 México D.F. (Mexico)

2013-08-15

A Hamiltonian approach is presented to study the two dimensional motion of damped electric charges in time dependent electromagnetic fields. The classical and the corresponding quantum mechanical problems are solved for particular cases using canonical transformations applied to Hamiltonians for a particle with variable mass. Green’s function is constructed and, from it, the motion of a Gaussian wave packet is studied in detail. -- Highlights: •Hamiltonian of a damped charged particle in time dependent electromagnetic fields. •Exact Green’s function of a charged particle in time dependent electromagnetic fields. •Time evolution of a Gaussian wave packet of a damped charged particle. •Classical and quantum dynamics of a damped electric charge.

Quantum and classical dissipation of charged particles

International Nuclear Information System (INIS)

Ibarra-Sierra, V.G.; Anzaldo-Meneses, A.; Cardoso, J.L.; Hernández-Saldaña, H.; Kunold, A.; Roa-Neri, J.A.E.

2013-01-01

A Hamiltonian approach is presented to study the two dimensional motion of damped electric charges in time dependent electromagnetic fields. The classical and the corresponding quantum mechanical problems are solved for particular cases using canonical transformations applied to Hamiltonians for a particle with variable mass. Green’s function is constructed and, from it, the motion of a Gaussian wave packet is studied in detail. -- Highlights: •Hamiltonian of a damped charged particle in time dependent electromagnetic fields. •Exact Green’s function of a charged particle in time dependent electromagnetic fields. •Time evolution of a Gaussian wave packet of a damped charged particle. •Classical and quantum dynamics of a damped electric charge

Prediction of turning stability using receptance coupling

Science.gov (United States)

Jasiewicz, Marcin; Powałka, Bartosz

2018-01-01

This paper presents an issue of machining stability prediction of dynamic "lathe - workpiece" system evaluated using receptance coupling method. Dynamic properties of the lathe components (the spindle and the tailstock) are assumed to be constant and can be determined experimentally based on the results of the impact test. Hence, the variable of the system "machine tool - holder - workpiece" is the machined part, which can be easily modelled analytically. The method of receptance coupling enables a synthesis of experimental (spindle, tailstock) and analytical (machined part) models, so impact testing of the entire system becomes unnecessary. The paper presents methodology of analytical and experimental models synthesis, evaluation of the stability lobes and experimental validation procedure involving both the determination of the dynamic properties of the system and cutting tests. In the summary the experimental verification results would be presented and discussed.

Collapse of large extra dimensions

International Nuclear Information System (INIS)

Geddes, James

2002-01-01

In models of spacetime that are the product of a four-dimensional spacetime with an 'extra' dimension, there is the possibility that the extra dimension will collapse to zero size, forming a singularity. We ask whether this collapse is likely to destroy the spacetime. We argue, by an appeal to the four-dimensional cosmic censorship conjecture, that--at least in the case when the extra dimension is homogeneous--such a collapse will lead to a singularity hidden within a black string. We also construct explicit initial data for a spacetime in which such a collapse is guaranteed to occur and show how the formation of a naked singularity is likely avoided

Mapping the receptivity of malaria risk to plan the future of control in Somalia.

Science.gov (United States)

Noor, Abdisalan Mohamed; Alegana, Victor Adagi; Patil, Anand Prabhakar; Moloney, Grainne; Borle, Mohammed; Yusuf, Fahmi; Amran, Jamal; Snow, Robert William

2012-01-01

To measure the receptive risks of malaria in Somalia and compare decisions on intervention scale-up based on this map and the more widely used contemporary risk maps. Cross-sectional community Plasmodium falciparum parasite rate (PfPR) data for the period 2007-2010 corrected to a standard age range of 2 to contemporary (2010) mean PfPR(2-10) and the maximum annual mean PfPR(2-10) (receptive) from the highest predicted PfPR(2-10) value over the study period as an estimate of receptivity. Randomly sampled communities in Somalia. Randomly sampled individuals of all ages. Cartographic descriptions of malaria receptivity and contemporary risks in Somalia at the district level. The contemporary annual PfPR(2-10) map estimated that all districts (n=74) and population (n=8.4 million) in Somalia were under hypoendemic transmission (≤10% PfPR(2-10)). Of these, 23% of the districts, home to 13% of the population, were under transmission of 10%-50% PfPR(2-10)) and the rest as hypoendemic. Compared with maps of receptive risks, contemporary maps of transmission mask disparities of malaria risk necessary to prioritise and sustain future control. As malaria risk declines across Africa, efforts must be invested in measuring receptivity for efficient control planning.

Phenomenology of spinless adjoints in two universal extra dimensions

International Nuclear Information System (INIS)

Ghosh, Kirtiman; Datta, Anindya

2008-01-01

We discuss the phenomenology of (1,1)-mode adjoint scalars in the framework of two Universal Extra Dimensions. The Kaluza-Klein (KK) towers of these adjoint scalars arise in the 4-dimensional effective theory from the 6th component of the gauge fields after compactification. Adjoint scalars can have KK-number conserving as well as KK-number violating interactions. We calculate the KK-number violating operators involving these scalars and two Standard Model fields. Decay widths of these scalars into different channels have been estimated. We have also briefly discussed pair-production and single production of such scalars at the Large Hadron Collider

Perturbation theory via Feynman diagrams in classical mechanics

OpenAIRE

Penco, R.; Mauro, D.

2006-01-01

In this paper we show how Feynman diagrams, which are used as a tool to implement perturbation theory in quantum field theory, can be very useful also in classical mechanics, provided we introduce also at the classical level concepts like path integrals and generating functionals.

Split Fermions in Extra Dimensions and Exponentially Small Cross-Sections at Future Colliders

Energy Technology Data Exchange (ETDEWEB)

Grossman, yuval

1999-09-22

We point out a dramatic new experimental signature for a class of theories with extra dimensions, where quarks and leptons are localized at slightly separated parallel ''walls'' whereas gauge and Higgs fields live in the bulk of the extra dimensions. The separation forbids direct local couplings between quarks and leptons, allowing for an elegant solution to the proton decay problem. We show that scattering cross sections for collisions of fermions which are separated in the extra dimensions vanish at energies high enough to probe the separation distance. This is because the separation puts a lower bound on the attainable impact parameter in the collision. We present cross sections for two body high energy scattering and estimate the power with which future colliders can probe this scenario, finding sensitivity to inverse fermion separations of order 10-70 TeV.

The Social Nature of Argumentative Practices: The Philosophy of Argument and Audience Reception

OpenAIRE

Paula Olmos

2018-01-01

Abstract: This article reviews Christopher W. Tindale’s The Philosophy of Argument and Audience Reception (Cambridge, 2015). Résumé: Cet article est une critique de The Philosophy of Argument and Audience Reception (Cambridge, 2015) de Christopher W. Tindale.

Critical properties of the classical XY and classical Heisenberg models: A renormalization group study

Science.gov (United States)

de Sousa, J. Ricardo; de Albuquerque, Douglas F.

1997-02-01

By using two approaches of renormalization group (RG), mean field RG (MFRG) and effective field RG (EFRG), we study the critical properties of the simple cubic lattice classical XY and classical Heisenberg models. The methods are illustrated by employing its simplest approximation version in which small clusters with one ( N‧ = 1) and two ( N = 2) spins are used. The thermal and magnetic critical exponents, Yt and Yh, and the critical parameter Kc are numerically obtained and are compared with more accurate methods (Monte Carlo, series expansion and ε-expansion). The results presented in this work are in excellent agreement with these sophisticated methods. We have also shown that the exponent Yh does not depend on the symmetry n of the Hamiltonian, hence the criteria of universality for this exponent is only a function of the dimension d.

Introduction to Extra Dimensions

Energy Technology Data Exchange (ETDEWEB)

Rizzo, Thomas G.; /SLAC

2010-04-29

Extra dimensions provide a very useful tool in addressing a number of the fundamental problems faced by the Standard Model. The following provides a very basic introduction to this very broad subject area as given at the VIII School of the Gravitational and Mathematical Physics Division of the Mexican Physical Society in December 2009. Some prospects for extra dimensional searches at the 7 TeV LHC with {approx}1 fb{sup -1} of integrated luminosity are provided.

Receptivity of Hypersonic Boundary Layers over Straight and Flared Cones

Science.gov (United States)

Balakumar, Ponnampalam; Kegerise, Michael A.

2010-01-01

The effects of adverse pressure gradients on the receptivity and stability of hypersonic boundary layers were numerically investigated. Simulations were performed for boundary layer flows over a straight cone and two flared cones. The steady and the unsteady flow fields were obtained by solving the two-dimensional Navier-Stokes equations in axi-symmetric coordinates using the 5th order accurate weighted essentially non-oscillatory (WENO) scheme for space discretization and using third-order total-variation-diminishing (TVD) Runge-Kutta scheme for time integration. The mean boundary layer profiles were analyzed using local stability and non-local parabolized stability equations (PSE) methods. After the most amplified disturbances were identified, two-dimensional plane acoustic waves were introduced at the outer boundary of the computational domain and time accurate simulations were performed. The adverse pressure gradient was found to affect the boundary layer stability in two important ways. Firstly, the frequency of the most amplified second-mode disturbance was increased relative to the zero pressure gradient case. Secondly, the amplification of first- and second-mode disturbances was increased. Although an adverse pressure gradient enhances instability wave growth rates, small nose-tip bluntness was found to delay transition due to the low receptivity coefficient and the resulting weak initial amplitude of the instability waves. The computed and measured amplitude-frequency spectrums in all three cases agree very well in terms of frequency and the shape except for the amplitude.

Cosmology in theories with extra dimensions

International Nuclear Information System (INIS)

Kolb, E.W.

1985-01-01

Some possible cosmological effects of the existence of extra compact dimensions are discussed. Particular attention is given to the possibility that extra dimensions might naturally lead to an inflationary Universe scenario

The receptiveness toward remotely supported myofeedback treatment

NARCIS (Netherlands)

Huis in 't Veld, M.H.A.; Voerman, Gerlienke; Hermens, Hermanus J.; Vollenbroek-Hutten, Miriam Marie Rosé

Remotely supported myofeedback treatment (RSMT) is considered to be a potentially valuable alternative to the conventional myofeedback treatment, as it might increase efficiency of care. This study was aimed at examining the receptiveness of potential end users (patients and professionals) with

Knockout mutations of insulin-like peptide genes enhance sexual receptivity in Drosophila virgin females.

Science.gov (United States)

Watanabe, Kazuki; Sakai, Takaomi

2016-01-01

In the fruitfly Drosophila melanogaster, females take the initiative to mate successfully because they decide whether to mate or not. However, little is known about the molecular and neuronal mechanisms regulating sexual receptivity in virgin females. Genetic tools available in Drosophila are useful for identifying molecules and neural circuits involved in the regulation of sexual receptivity. We previously demonstrated that insulin-producing cells (IPCs) in the female brain are critical to the regulation of female sexual receptivity. Ablation and inactivation of IPCs enhance female sexual receptivity, suggesting that neurosecretion from IPCs inhibits female sexual receptivity. IPCs produce and release insulin-like peptides (Ilps) that modulate various biological processes such as metabolism, growth, lifespan and behaviors. Here, we report a novel role of the Ilps in sexual behavior in Drosophila virgin females. Compared with wild-type females, females with knockout mutations of Ilps showed a high mating success rate toward wild-type males, whereas wild-type males courted wild-type and Ilp-knockout females to the same extent. Wild-type receptive females retard their movement during male courtship and this reduced female mobility allows males to copulate. Thus, it was anticipated that knockout mutations of Ilps would reduce general locomotion. However, the locomotor activity in Ilp-knockout females was significantly higher than that in wild-type females. Thus, our findings indicate that the high mating success rate in Ilp-knockout females is caused by their enhanced sexual receptivity, but not by improvement of their sex appeal or by general sluggishness.

Receptivity of a high-speed boundary layer to temperature spottiness

OpenAIRE

Fedorov, A. V.; Ryzhov, A. A.; Soudakov, V. G.; Utyuzhnikov, S. V.

2013-01-01

Two-dimensional direct numerical simulation (DNS) of the receptivity of a flat-plate boundary layer to temperature spottiness in the Mach 6 free stream is carried out. The influence of spottiness parameters on the receptivity process is studied. It is shown that the temperature spots propagating near the upper boundary-layer edge generate mode F inside the boundary layer. Further downstream mode F is synchronized with unstable mode S (Mack second mode) and excites the latter via the inter-mod...

Contrast normalization contributes to a biologically-plausible model of receptive-field development in primary visual cortex (V1)

Science.gov (United States)

Willmore, Ben D.B.; Bulstrode, Harry; Tolhurst, David J.

2012-01-01

Neuronal populations in the primary visual cortex (V1) of mammals exhibit contrast normalization. Neurons that respond strongly to simple visual stimuli – such as sinusoidal gratings – respond less well to the same stimuli when they are presented as part of a more complex stimulus which also excites other, neighboring neurons. This phenomenon is generally attributed to generalized patterns of inhibitory connections between nearby V1 neurons. The Bienenstock, Cooper and Munro (BCM) rule is a neural network learning rule that, when trained on natural images, produces model neurons which, individually, have many tuning properties in common with real V1 neurons. However, when viewed as a population, a BCM network is very different from V1 – each member of the BCM population tends to respond to the same dominant features of visual input, producing an incomplete, highly redundant code for visual information. Here, we demonstrate that, by adding contrast normalization into the BCM rule, we arrive at a neurally-plausible Hebbian learning rule that can learn an efficient sparse, overcomplete representation that is a better model for stimulus selectivity in V1. This suggests that one role of contrast normalization in V1 is to guide the neonatal development of receptive fields, so that neurons respond to different features of visual input. PMID:22230381

Effective Strategies for Turning Receptive Vocabulary into Productive Vocabulary in EFL Context

Science.gov (United States)

Faraj, Avan Kamal Aziz

2015-01-01

Vocabulary acquisition has been a main concern of EFL English teachers and learners. There have been tons of research to examine the student's level of receptive vocabulary and productive vocabulary, but no research has conducted on how turning receptive vocabulary into productive vocabulary. This study has reported the impact of the teaching…

Function of Classic Music in TV Art%论古典音乐在电视文艺中的运用

Institute of Scientific and Technical Information of China (English)

张宜霞

2014-01-01

The form of music varies with the change of times and the prospering of popular music sees the decline of classic music. However, classics can never be obscured and more and more TV programs find the effect of reception by the application of classic music. This paper, with special reference to the application of classic music in various shows, elaborates the important role of classic music in TV art and the developing tendency of classic music.%伴随着时代的变迁，音乐的形式在不断发生变化。流行音乐等的出现使得古典音乐的地位日渐衰退，然而古典音乐在电视文艺中发挥着其他音乐形式不可替代的作用。文章从我国综艺节目中的古典音乐应用实际的例子出发，阐述古典音乐在电视文艺中的重要作用以及其未来的发展方向。

Technological Development and Its Impact on Student Reception of a Campus Radio

Science.gov (United States)

Mohamed, Shafizan; Wok, Saodah; Lahabou, Mahaman

2018-01-01

In 2011, a study was conducted to look at students' reception of IIUM.FM, a newly launched online campus radio. Using the Technological Acceptance Model (TAM), the study found that factors such as perceived ease of use, perceived usefulness, and attitude highly influenced audience reception of the online radio. In 2016, a corresponding study,…

The Receptive-Expressive Gap in the Vocabulary of Young Second-Language Learners: Robustness and Possible Mechanisms