cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Coherence loss and revivals in atomic interferometry: A quantum-recoil analysis
Creators: name: Davidovic, M.
name: Sanz, A. S.
name: Bozic, M.
name: Arsenovic, D.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Physics (quant-ph)
subject: Atomic Physics (physics.atom-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: The coherence effects induced by external photons coupled to matter waves inside a Mach-Zehnder three-grating interferometer are analyzed. Alternatively to atom-photon entanglement scenarios, the model considered here only relies on the atomic wave function and the momentum shift induced in it by the photon scattering events. A functional dependence is thus found between the observables, namely the fringe visibility and the phase shift, and the transversal momentum transfer distribution. A good quantitative agreement is found when comparing the results obtained from our model with the experimental data.
description: 18 pages, 4 figures
Entropic Corrections to Coulomb's Law
Creators: name: Hendi, S. H.
name: Sheykhi, A.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Two well-known quantum corrections to the area law have been introduced in the literatures, namely, logarithmic and power-law corrections. Logarithmic corrections, arises from loop quantum gravity due to thermal equilibrium fluctuations and quantum fluctuations, while, power-law correction appears in dealing with the entanglement of quantum fields in and out the horizon. Inspired by Verlinde's argument on the entropic force, and assuming the quantum corrected relation for the entropy, we propose the entropic origin for the Coulomb's law in this note. Also we investigate the Uehling potential as a radiative correction to Coulomb potential in 1-loop order and show that for some value of distance the entropic corrections of the Coulomb's law is compatible with the vacuum-polarization correction in QED. So, we derive modified Coulomb's law as well as the entropy corrected Poisson's equation which governing the evolution of the scalar potential $ϕ$. Our study further supports the unification of gravity and electromagnetic interactions based on the holographic principle.
description: 17 pages, 5 figures, accepted in IJTP
Synchronous Spatial Oscillation of Electron- and Mn-Spin Polarizations in Dilute-Magnetic-Semiconductor Quantum Wells under Spin-Orbit Effective Magnetic Fields
Creators: name: Tsuchiya, Takuma
Publisher: name: arXiv
Year: 2011
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: In semiconductors, spin-orbit effective magnetic fields, i.e., the Rashba and Dresselhaus fields, are used to control electron-spin polarization. This operation, however, destroys the electron-spin coherence, and the spin polarization is limited to the vicinity of a ferromagnetic source electrode. In this paper, we propose the use of dilute magnetic semiconductors to improve the coherence of spatially oscillating electron-spin polarization. In dilute magnetic semiconductors, the electron-spin polarization near the source electrode dynamically induces the local spin polarization of magnetic impurities through s-d spin-flip scattering. This impurity-spin polarization improves, in turn, the coherence of the electron-spin polarization, and this improved electron-spin polarization induces impurity-spin polarization farther in the adjacent region. Because of this positive feedback, the coherent and synchronized spatial oscillations of electron- and impurity-spin polarizations grow cooperatively. A numerical calculation for a CdMnTe quantum well demonstrates the validity of this mechanism.
description: 30 pages, 6 figures, 1 table
Effect of eye movements on the magnitude of functional magnetic resonance imaging responses in extrastriate cortex during visual motion perception
Creators: name: Freitag, P.
name: Greenlee, Mark W.
name: Lacina, T.
name: Scheffler, K.
name: Radü, E. W.
Publisher: name: Universität Regensburg
Year: 1998
Subjects: subject: Functional MRI, BOLD effect, Motion perception, Oculomotor pursuit, Human
subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: We have studied the effects of pursuit eye movements on the functional magnetic resonance imaging (fMRI) responses in extrastriate visual areas during visual motion perception. Echoplanar imaging of 10–12 image planes through visual cortex was acquired in nine subjects while they viewed sequences of random-dot motion. Images obtained during stimulation periods were compared with baseline images, where subjects viewed a blank field. In a subsidiary experiment, responses to moving dots, viewed under conditions of fixation or pursuit, were compared with those evoked by static dots. Eye movements were recorded with MR-compatible electro-oculographic (EOG) electrodes. Our findings show an enhanced level of activation (as indexed by blood-oxygen level-dependent contrast) during pursuit compared with fixation in two extrastriate areas. The results support earlier findings on a motion-specific area in lateral occipitotemporal cortex (human V5). They also point to a further site of activation in a region approximately 12 mm dorsal of V5. The fMRI response in V5 during pursuit is significantly enhanced. This increased response may represent additional processing demands required for the control of eye movements.
Impairment in preattentive visual processing in patients with Parkinson's disease
Creators: name: Lieb, K.
name: Brucker, S.
name: Bach, M.
name: Els, T.
name: Lücking, C. H.
name: Greenlee, Mark W.
Publisher: name: Universität Regensburg
Year: 1999
Subjects: subject: Parkinson's disease, visual search, preattentive processing, stimulus orientation
subject: 570 Biowissenschaften, Biologie

description: We explored the possibility of whether preattentive visual processing is impaired in Parkinson's disease. With this aim, visual discrimination thresholds for orientation texture stimuli were determined in two separate measurement sessions in 16 patients with idiopathic Parkinson's disease. The results were compared with those of 16 control subjects age-matched and 16 young healthy volunteers. Discrimination thresholds were measured in a four-alternative spatial forced-choice paradigm, in which subjects judged the location of a target embedded in a background of distractors. Four different stimulus configurations were employed: (i) a group of vertical targets among horizontal distractors (`vertical line targets'); (ii) targets with varying levels of orientation difference on a background of spatially filtered vertically oriented noise (`Gaussian filtered noise'); (iii) one `L' among 43 `+' signs (`texton'), all of which assess preattentive visual processing; and (iv) control condition, of one `L' among 43 `T' distractors (`non-texton' search target), which reflects attentive visual processing. In two of the preattentive tasks (filtered noise and texton), patients with Parkinson's disease required significantly greater orientation differences and longer stimulus durations, respectively. In contrast, their performance in the vertical line target and non-texton search target was comparable to that of the matched control subjects. These differences were more pronounced in the first compared with the second session. Duration of illness and age within the patient group correlated significantly with test performance. In all conditions tested, the young control subjects performed significantly better than the more elderly control group, further indicating an effect of age on this form of visual processing. The results suggest that, in addition to the well documented impairment in retinal processing, idiopathic Parkinson's disease is associated with a deficit in preattentive cortical visual processing.
Random subshifts of finite type
Creators: name: McGoff, Kevin
Publisher: name: arXiv
Year: 2010
Subjects: subject: Probability (math.PR)
subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: Let $X$ be an irreducible shift of finite type (SFT) of positive entropy, and let $B_n(X)$ be its set of words of length $n$. Define a random subset $ω$ of $B_n(X)$ by independently choosing each word from $B_n(X)$ with some probability $α$. Let $X_ω$ be the (random) SFT built from the set $ω$. For each $0\leq α\leq1$ and $n$ tending to infinity, we compute the limit of the likelihood that $X_ω$ is empty, as well as the limiting distribution of entropy for $X_ω$. For $α$ near 1 and $n$ tending to infinity, we show that the likelihood that $X_ω$ contains a unique irreducible component of positive entropy converges exponentially to 1. These results are obtained by studying certain sequences of random directed graphs. This version of "random SFT" differs significantly from a previous notion by the same name, which has appeared in the context of random dynamical systems and bundled dynamical systems.
description: Published in at http://dx.doi.org/10.1214/10-AOP636 the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Correction: Humoral immune response to inactivated COVID-19 vaccination at the 3rd month among people living with HIV
Creators: name: Zou, Shi
name: Wu, Songjie
name: Ming, Fangzhao
name: Zhang, Zhiyue
name: Xing, Zhongyuan
name: Tang, Weiming
name: Wu, Mengmeng
name: Liu, Jinli
name: Tang, Weiming
name: Guo, Wei
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2024

description: Correction to "Humoral immune response to inactivated COVID-19 vaccination at the 3rd month among people living with HIV"
Attentional suppression of activity in the human visual cortex
Creators: name: Smith, A. T.
name: Singh, K. D.
name: Greenlee, Mark W.
Publisher: name: Universität Regensburg
Year: 2000
Subjects: subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: We have used fMRI to examine the nature of the changes that occur in the human visual cortex when an observer attends to a particular location in the visual image. Previous studies have shown that the magnitude of the response to a visual stimulus is increased when the observer attends to the stimulus. We show that, in addition, attention to a particular location results in a widespread suppression of activity levels at all other locations. This suggests that a key mechanism of attentional modulation may be that spontaneous (baseline) levels of neural activity are adjusted in a position-dependent manner across the entire visual field.
Dirac Operator on Complex Manifolds and Supersymmetric Quantum Mechanics
Creators: name: Ivanov, E. A.
name: Smilga, A. V.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences
subject: 81Q60, 81T60, 32Qxx

description: We explore a new simple N=2 SQM model describing the motion over complex manifolds in external gauge fields. The nilpotent supercharge Q of the model can be interpreted as a (twisted) exterior holomorphic derivative, such that the model realizes the twisted Dolbeault complex. The sum Q + \bar Q can be interpreted as the Dirac operator: the standard Dirac operator if the manifold is Kähler and a certain "truncated" Dirac operator for a generic complex manifold. Focusing on the Kähler case, we give new simple physical proofs of the two mathematical facts: (i) the equivalence of the twisted Dirac and twisted Dolbeault complexes and (ii) the Atiyah-Singer theorem.
description: 0 + 30 pages, essential revision, new comments and refs. added, typos corrected, published version
Essays on entrepreneurship and closely-held firms
Creators: name: Xu, Ting
Publisher: name: University of British Columbia
Year: 2017

description: This thesis contains three essays on entrepreneurship and close-held firms. The first essay examines the feedback role of crowdfunding, a new financing method that allows entrepreneurs to raise finance online directly from the public. Using a novel dataset from Kickstarter, I show that crowdfunding outcome signals to entrepreneurs the product market potential of their projects and guides entrepreneurs’ subsequent commercialization decisions. Exploiting weather-induced variation in pledged funds within unfunded projects (which receive no financing), I find that entrepreneurs who received more pledging are more likely to complete and commercialize their projects. Consistent with the real option value of crowdfunding feedback, entrepreneurs on Kickstarter launch riskier projects when crowdfunding becomes more costly relative to alternative financing. These results highlight the role of crowdfunding in improving the information environment faced by early-stage entrepreneurs. The second essay, co-authored with Jan Bena, studies how product market competition affects firms’ ownership structures. Using a large sample of closely held firms in eighteen European countries, we show that firms operating in more competitive environments have lower inside ownership and that the stakes of their outside shareholders are more dispersed. These results are explained by competition increasing the need to raise external equity and reducing private control benefits. Our findings suggest that, by changing corporate ownership structure, competition mitigates incentive misalignment among shareholders, leading to better firm performance and gains in economic efficiency. The third essay studies the effect of shareholder excess control rights on creditors. I show that excess control rights can benefit creditors despite its negative effect previously documented on minority shareholders. Using a sample of U.S. dual-class firms, I find that dual-class firms take less business and financial risk than similar single-class firms, consistent with controlling insiders’ emphasis on long-term survival to access ongoing private benefits of control. Such risk avoidance translates into lower borrowing costs for dual-class firms. Further, lenders seem to be able to use specific covenants to prevent potential expropriations by controlling insiders. These results suggest that the overall effect of excess control rights on firm value may not be as negative as we previously thought.
The influence of appetitive and aversive stimuli on subjective temporal acuity
Creators: name: Roberts, Kevin H.
Publisher: name: University of British Columbia
Year: 2017

description: Anecdotal reports that time “flies by” or “slows down” during emotional events are supported by evidence that the motivational relevance of stimuli influences subsequent duration judgments. Yet it is unknown whether the subjective quality of events as they unfold is altered by motivational relevance. In a novel paradigm, we measured the subjective experience of moment-to-moment visual perception. Participants judged the temporal smoothness of high-approach positive (desserts), negative (e.g. bodily mutilation), and neutral images (commonplace scenes) as they faded to black. Results revealed approach-motivated blurring (AMB), such that positive stimuli were judged as smoother and negative stimuli as choppier relative to neutral stimuli. Participant ratings of approach-motivation predicted perceived fade smoothness after controlling for low-level stimulus features. Electrophysiological data indicated AMB modulated relatively rapid perceptual activation. Results indicate that stimulus value influences subjective temporal perceptual acuity, with approach-motivating stimuli eliciting perception of a “blurred” frame rate characteristic of speeded motion.
Towards a Basis for Planar Two-Loop Integrals
Creators: name: Gluza, Janusz
name: Kajda, Krzysztof
name: Kosower, David A.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The existence of a finite basis of algebraically independent one-loop integrals has underpinned important developments in the computation of one-loop amplitudes in field theories and gauge theories in particular. We give an explicit construction reducing integrals to a finite basis for planar integrals at two loops, both to all orders in the dimensional regulator e, and also when all integrals are truncated to O(e). We show how to reorganize integration-by-parts equations to obtain elements of the first basis efficiently, and how to use Gram determinants to obtain additional linear relations reducing this all-orders basis to the second one. The techniques we present should apply to non-planar integrals, to integrals with massive propagators, and beyond two loops as well.
description: 55 pages, 8 figures, Mathematica file for some formulae; final journal version, typos corrected
Modality shift effects mimic multisensory interactions: an event-related potential study
Creators: name: Gondan, Matthias
name: Vorberg, Dirk
name: Greenlee, Mark W.
Publisher: name: Universität Regensburg
Year: 2007
Subjects: subject: Multisensory processes, Event-related potentials, Divided attention, Modality shift effect
subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: A frequent approach to study interactions of the auditory and the visual system is to measure event-related potentials (ERPs) to auditory, visual, and auditory-visual stimuli (A, V, AV). A nonzero result of the AV − (A + V) comparison indicates that the sensory systems interact at a specific processing stage. Two possible biases weaken the conclusions drawn by this approach: first, subtracting two ERPs from one requires that A, V, and AV do not share any common activity. We have shown before (Gondan and Röder in Brain Res 1073–1074:389–397, 2006) that the problem of common activity can be avoided using an additional tactile stimulus (T) and evaluating the ERP difference (T + TAV) − (TA + TV). A second possible confound is the modality shift effect (MSE): for example, the auditory N1 is increased if an auditory stimulus follows a visual stimulus, whereas it is smaller if the modality is unchanged (ipsimodal stimulus). Bimodal stimuli might be affected less by MSEs because at least one component always matches the preceding trial. Consequently, an apparent amplitude modulation of the N1 would be observed in AV. We tested the influence of MSEs on auditory-visual interactions by comparing the results of AV − (A + V) using (a) all stimuli and using (b) only ipsimodal stimuli. (a) and (b) differed around 150 ms, this indicates that AV − (A + V) is indeed affected by the MSE. We then formally and empirically demonstrate that (T + TAV) − (TA + TV) is robust against possible biases due to the MSE.
Magnetic-field effect on excitonic condensation emergent in extended Falicov-Kimball model
Creators: name: Ohta, Naoya
name: Nasu, Joji
Publisher: name: arXiv
Year: 2025
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We investigate the effects of magnetic fields on excitonic condensation in the extended Falicov-Kimball model, which is a spinless two-orbital Hubbard model with orbital splitting. In lattice systems under magnetic fields up to several tens of teslas, Zeeman effects on electron spins have been extensively studied, while the impact on orbital motion has often been considered negligible. However, the recent capability to generate ultra-high magnetic fields exceeding 1000 T has renewed interest in understanding their influence on ordered phases in correlated electron systems, beyond spin-related phenomena. To examine these effects, we incorporate a magnetic field into the extended Falicov-Kimball model by introducing the Peierls phase into the transfer integrals, enabling the study of orbital motion. Using the Hartree-Fock approximation, we reveal a nonmonotonic response of the excitonic order parameter to increasing magnetic fields. At sufficiently high fields, the excitonic order is suppressed, resulting in a disordered insulating state characterized by partial occupation of the two orbitals with nonzero Chern numbers. This state is distinct from a fully orbital-polarized configuration. Furthermore, our analysis of an excitonic supersolid phase, in which excitonic and orbital orders coexist, demonstrates that orbital order remains robust under magnetic fields, while excitonic condensation is suppressed. These findings provide insights into the interplay between orbital motion and magnetic fields in multi-orbital correlated electron systems.
description: 12 pages, 8 figures
Relationship between motion VEP and perceived velocity of gratings: effects of stimulus speed and motion adaptation
Creators: name: Müller, Rolf
name: Bochmann, Gunder
name: Greenlee, Mark W.
name: Göpfert, Edith
Publisher: name: Universität Regensburg
Year: 2003
Subjects: subject: motion adaptation, motion VEP, perceived speed, speed channels, stationary adaptation
subject: 150 Psychologie

description: The N200 amplitude of the motion-onset VEP evoked by a parafoveal grating of variable speed (0.25–13.5°/s), constant spatial frequency (2 cpd), contrast (4%), and direction (horizontally rightward) was studied before and after adaptation to a stationary or drifting grating (1 or 4°/s). Psychophysical measurements were made simultaneously of the perceived speed. In the unadapted condition the slope of the N200 amplitude versus speed function is positive, but lower for high compared to low speeds. The N200 amplitude increases slightly after stationary adaptation. An increase in perceived speed is also evident after stationary adaptation. This increase is more pronounced for low compared to high speeds. Motion adaptation reduces N200 amplitudes over the entire speed range, whereas perceived speeds change from under-estimation to over-estimation when the speed exceeds 1.8°/s after 1°/s adaptation and 4.5°/s after 4°/s adaptation. The simultaneous evaluation of motion VEP and psychophysical results supports the view that the neurons generating the N200 component are also involved in speed perception. The data suggest the existence of a limited number (three or more) speed channels.
A controlled vocabulary of archaeological features in Austria for the PhD project Roman Rural Landscapes in Noricum (RRLN-CV)
Creators: name: Hagmann, Dominik
Publisher: name: self-publishing
Year: 2021
Subjects: controlled vocabulary
Noricum
thesaurus
taxonomy
rural settlements
ÖFOS 2012 -- HUMANITIES (6) -- History, Archaeology (601) -- History, Archaeology (6010) -- Classical archaeology (601010)
ÖFOS 2012 -- GEISTESWISSENSCHAFTEN (6) -- Geschichte, Archäologie (601) -- Geschichte, Archäologie (6010) -- Klassische Archäologie (601010)
ÖFOS 2012 -- HUMANITIES (6) -- History, Archaeology (601) -- History, Archaeology (6010) -- Virtual archeology (601026)
ÖFOS 2012 -- GEISTESWISSENSCHAFTEN (6) -- Geschichte, Archäologie (601) -- Geschichte, Archäologie (6010) -- Virtuelle Archäologie (601026)
Getty Art & Architecture Thesaurus, monolingual thesauri

description: This controlled vocabulary is based on the database of archaeological features maintained by the Austrian Federeal Monuments Authority (Bundesdenkmalamt, BDA). It is based on a template from https://skos-play.sparna.fr/
Canonical quantization of a massive Weyl field
Creators: name: Dvornikov, Maxim
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We construct a consistent theory of a quantum massive Weyl field. We start with the formulation of the classical field theory approach for the description of massive Weyl fields. It is demonstrated that the standard Lagrange formalism cannot be applied for the studies of massive first-quantized Weyl spinors. Nevertheless we show that the classical field theory description of massive Weyl fields can be implemented in frames of the Hamilton formalism or using the extended Lagrange formalism. Then we carry out a canonical quantization of the system. The independent ways for the quantization of a massive Weyl field are discussed. We also compare our results with the previous approaches for the treatment of massive Weyl spinors. Finally the new interpretation of the Majorana condition is proposed.
description: 6 pages in Revtex 4.1, two columns, no figures; paper is significantly revised, the discussion of the extended Lagrange formalism is included, several new references are added; accepted for publication in Foundation of Physics
Weak gravitational lensing cross-correlations
Creators: name: Tröster, Tilman
Publisher: name: University of British Columbia
Year: 2017

description: The matter content of the Universe is dominated by dark matter. Beyond its abundance and its lack of non-gravitational interactions with standard model matter, little is known about the nature of dark matter. This thesis attempts to illuminate different aspects of dark matter by using gravitational lensing in conjunction with other cosmological probes. Gravitational lensing describes the deflection of light by gravitational potentials and is a direct and unbiased probe of the matter distribution in the Universe. We investigate the weakly interacting massive particle (WIMP) model of dark matter by performing a tomographic and spectral cross-correlation between weak gravitational lensing from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), Red Cluster Sequence Lensing Survey (RCSLenS), and Kilo-Degree Survey (KiDS), and gamma rays from Fermi-LAT. The non-detection of a correlation allows us to constrain the allowed masses, annihilation cross-sections, and decay rates of WIMP dark matter. Even though most matter in the Universe is dark matter, about 16% is baryonic matter. To make precision measurements of the dark matter distribution with gravitational lensing, it is therefore necessary to understand the behaviour and distribution of baryonic matter. We measure and analyse the cross-correlation between weak gravitational lensing from RCSLenS and the thermal Sunyaev-Zeldovich (tSZ) effect from the Planck satellite to constrain the effect of baryon physics on the matter distribution. Models of gravitational lensing often make use of a range of approximations. We study the effect of dropping these approximations on the cross-correlation between gravitational lensing and tSZ by performing a detailed calculation up to fourth order in the gravitational potential. We find that the common approximations are sufficiently accurate even for future surveys. Finally, we explore the growth of structure and the effect of residual weak lensing systematics in a tomographic cross-correlation between weak gravitational lensing from KiDS and lensing of the cosmic microwave background (CMB) from Planck.
México: elecciones locales 2023
Creators: name: Estrada, Karla
Publisher: name: Zenodo
Year: 2023
Subjects: Elecciones
Elecciones en México

description: Estrada, Karla. 2023. México: elecciones locales 2023. México: Observatorio de Reformas Políticas en América Latina, IIJ-UNAM y Organización de los Estados Americanos (OEA).
Robust rank correlation based screening
Creators: name: Li, Gaorong
name: Peng, Heng
name: Zhang, Jun
name: Zhu, Lixing
Publisher: name: arXiv
Year: 2010
Subjects: subject: Methodology (stat.ME)
subject: Statistics Theory (math.ST)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: Independence screening is a variable selection method that uses a ranking criterion to select significant variables, particularly for statistical models with nonpolynomial dimensionality or "large p, small n" paradigms when p can be as large as an exponential of the sample size n. In this paper we propose a robust rank correlation screening (RRCS) method to deal with ultra-high dimensional data. The new procedure is based on the Kendall τcorrelation coefficient between response and predictor variables rather than the Pearson correlation of existing methods. The new method has four desirable features compared with existing independence screening methods. First, the sure independence screening property can hold only under the existence of a second order moment of predictor variables, rather than exponential tails or alikeness, even when the number of predictor variables grows as fast as exponentially of the sample size. Second, it can be used to deal with semiparametric models such as transformation regression models and single-index models under monotonic constraint to the link function without involving nonparametric estimation even when there are nonparametric functions in the models. Third, the procedure can be largely used against outliers and influence points in the observations. Last, the use of indicator functions in rank correlation screening greatly simplifies the theoretical derivation due to the boundedness of the resulting statistics, compared with previous studies on variable screening. Simulations are carried out for comparisons with existing methods and a real data example is analyzed.
description: Published in at http://dx.doi.org/10.1214/12-AOS1024 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org). arXiv admin note: text overlap with arXiv:0903.5255
Neural Correlates of Coherent Audiovisual Motion Perception
Creators: name: Baumann, Oliver
name: Greenlee, Mark W.
Publisher: name: Universität Regensburg
Year: 2007
Subjects: subject: audiovisual integration, brain imaging, coherence, multimodal, superior temporal gyrus, supramarginal gyrus
subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: Real-life moving objects are often detected by multisensory cues. We investigated the cortical activity associated with coherent visual motion perception in the presence of a stationary or moving auditory noise source using functional magnetic resonance imaging. Twelve subjects judged episodes of 5-s random-dot motion containing either no (0%) or abundant (16%) coherent direction information. Auditory noise was presented with the displayed visual motion that was moving in phase, was moving out-of-phase, or was stationary. Subjects judged whether visual coherent motion was present, and if so, whether the auditory noise source was moving in phase, was moving out-of-phase, or was not moving. Performance was greatest for a moving sound source that was in phase with the visual coherent dot motion compared with when it was in antiphase. A random-effects analysis revealed that auditory motion activated extended regions in both cerebral hemispheres in the superior temporal gyrus (STG), with a right-hemispheric preponderance. Combined audiovisual motion led to activation clusters in the STG, the supramarginal gyrus, the superior parietal lobule, and the cerebellum. The size of the activated regions was substantially larger than that evoked by either visual or auditory motion alone. The congruent audiovisual motion evoked the most extensive activation pattern, exhibiting several exclusively activated subregions.
Primitive orthogonal idempotents for R-trivial monoids
Creators: name: Berg, Chris
name: Bergeron, Nantel
name: Bhargava, Sandeep
name: Saliola, Franco
Publisher: name: arXiv
Year: 2010
Subjects: subject: Representation Theory (math.RT)
subject: FOS: Mathematics

description: We construct a recursive formula for a complete system of primitive orthogonal idempotents for any $R$-trivial monoid. This uses the newly proved equivalence between the notions of $R$-trivial monoid and weakly ordered monoid.
description: Journal of Algebra, 2011
Event-related fMRI responses in the human frontal eye fields in a randomized pro- and antisaccade task
Creators: name: Cornelissen, Frans W.
name: Kimmig, Hubert
name: Schira, Mark
name: Rutschmann, Roland M.
name: Maguire, R. Paul
name: Broerse, Annelies
name: Boer, Johan A. Den
name: Greenlee, Mark W.
Publisher: name: Universität Regensburg
Year: 2002
Subjects: subject: Event-related fMRI, Prosaccades, Antisaccades, Frontal eye fields
subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: We examined whether the frontal eye fields (FEF) are involved in the suppression of reflexive saccades. Simultaneous recording of horizontal eye movements and functional magnetic resonance imaging enabled us to perform a randomized pro- and antisaccade task and to sort blood oxygenation level dependent (BOLD) time series on the basis of task performance. Saccadic reaction time distributions were comparable across tasks indicating a similar effort in preprocessing of the saccades. Furthermore, we found similar BOLD activation in FEF during both correctly performed pro- and antisaccades. Frontal eye field activation started prior to target presentation and saccade generation. While we observed only few erroneous antisaccades, these were associated with a decrease in BOLD activity prior to target presentation, and increased BOLD activity after target presentation relative to correctly performed antisaccades. These findings are consistent with a role of the FEF in the suppression of reflexive saccades. The increase in activity after target presentation for antisaccade errors can only be indirectly linked to such a role but may also reflect activity related to the generation of a correction saccade. Frontal eye field BOLD activity may further represent general arousal, preparatory set, shortterm memory, or salience-map related activity.
Working memory in primate sensory systems
Creators: name: Pasternak, Tatiana
name: Greenlee, Mark W.
Publisher: name: Universität Regensburg
Year: 2005
Subjects: subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: Sensory working memory consists of the short-term storage of sensory stimuli to guide behaviour. There is increasing evidence that elemental sensory dimensions — such as object motion in the visual system or the frequency of a sound in the auditory system — are stored by segregated feature-selective systems that include not only the prefrontal and parietal cortex, but also areas of sensory cortex that carry out relatively early stages of processing. These circuits seem to have a dual function: precise sensory encoding and short-term storage of this information. New results provide insights into how activity in these circuits represents the remembered sensory stimuli.
A Note on Massive Scalar Hypermultiplet in Projective Hyperspace
Creators: name: Jain, Dharmesh
name: Siegel, Warren
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We analyze the massive 4D scalar multiplet in 'reformulated' projective N=2 superspace (hyperspace) from both 4D and 6D perspectives.
description: 1+7+1 pages, 1 figure; minor corrections made in v2
Dissociation of neural correlates of verbal and non-verbal visual working memory with different delays
Creators: name: Rothmayr, Christoph
name: Baumann, Oliver
name: Endestad, Tor
name: Rutschmann, Roland M.
name: Magnussen, Svein
name: Greenlee, Mark W.
Publisher: name: Universität Regensburg
Year: 2007
Subjects: subject: Retention Interval, Work Memory, Inferior Frontal Gyrus, Superior Temporal Gyrus, Supramarginal Gyrus
subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: Background Dorsolateral prefrontal cortex (DLPFC), posterior parietal cortex, and regions in the occipital cortex have been identified as neural sites for visual working memory (WM). The exact involvement of the DLPFC in verbal and non-verbal working memory processes, and how these processes depend on the time-span for retention, remains disputed. Methods We used functional MRI to explore the neural correlates of the delayed discrimination of Gabor stimuli differing in orientation. Twelve subjects were instructed to code the relative orientation either verbally or non-verbally with memory delays of short (2 s) or long (8 s) duration. Results Blood-oxygen level dependent (BOLD) 3-Tesla fMRI revealed significantly more activity for the short verbal condition compared to the short non-verbal condition in bilateral superior temporal gyrus, insula and supramarginal gyrus. Activity in the long verbal condition was greater than in the long non-verbal condition in left language-associated areas (STG) and bilateral posterior parietal areas, including precuneus. Interestingly, right DLPFC and bilateral superior frontal gyrus was more active in the non-verbal long delay condition than in the long verbal condition. Conclusion The results point to a dissociation between the cortical sites involved in verbal and non-verbal WM for long and short delays. Right DLPFC seems to be engaged in non-verbal WM tasks especially for long delays. Furthermore, the results indicate that even slightly different memory maintenance intervals engage largely differing networks and that this novel finding may explain differing results in previous verbal/non-verbal WM studies.
Functional magnetic resonance imaging evidence for binocular interactions in human visual cortex
Creators: name: Büchert, M.
name: Greenlee, M. W.
name: Rutschmann, Roland M.
name: Kraemer, F. M.
name: Luo, Feng
name: Hennig, J.
Publisher: name: Universität Regensburg
Year: 2002
Subjects: subject: Visual cortex, Ocular dominance columns, Binocular interactions, fMRI, BOLD effect, Dichoptic stimulation
subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: Using functional magnetic resonance imaging (fMRI), we explored the binocular interactions occurring when subjects viewed dichoptically presented checkerboard stimuli. A flickering radial checkerboard was presented to each eye of the subject, while T2*-weighted images were acquired over the visual cortex with gradient-echo, echoplanar sequences. We compared responses in striate and extrastriate visual cortex under four conditions: both eyes were stimulated at the same time (binocular condition), each eye was stimulated in alternation (monocular condition) or first the one eye then the other eye was stimulated (left eye first - right eye trailing, or vice versa). The results indicate that only the striate area, in and near the calcarine fissure, shows significant differences for these stimulation conditions. These differences are not evident in more remote extrastriate or associational visual areas, although the BOLD response in the stimulation-rest comparison was robust. These results suggest that the effect could be related to inhibitory interactions across ocular dominance columns in striate visual cortex.
Outcome Independence of Entanglement in One-Way Computation
Creators: name: Sasaki, Toshihiko
name: Ichikawa, Tsubasa
name: Tsutsui, Izumi
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We show that the various intermediate states appearing in the process of one-way computation at a given step of measurement are all equivalent modulo local unitary transformations. This implies, in particular, that all those intermediate states share the same entanglement irrespective of the measurement outcomes, indicating that the process of one-way computation is essentially unique with respect to local quantum operations.
description: 6 pages, 4 figures
The tame and the wild automorphisms of an affine quadric threefold
Creators: name: Lamy, Stéphane
name: Vénéreau, Stéphane
Publisher: name: arXiv
Year: 2011
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 14R, 14R10

description: We prove the existence of wild automorphisms on an affine quadric threefold. The method we use is an adaptation of the one used by Shestakov and Umirbaev to prove the existence of wild automorphisms on the affine three dimensional space.
description: Minor corrections. To appear in Journal of the Mathematical Society of Japan
Effects of nonspatial selective and divided visual attention on fMRI BOLD responses
Creators: name: Weerda, Riklef
name: Vallines, Ignacio
name: Thomas, James P.
name: Rutschmann, Roland M.
name: Greenlee, Mark W.
Publisher: name: Universität Regensburg
Year: 2006
Subjects: subject: Stimulus uncertainty, Visual attention, Colour discrimination, Shape perception, Functional MRI
subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: Using an uncertainty paradigm and functional magnetic resonance imaging (fMRI) we studied the effect of nonspatial selective and divided visual attention on the activity of specific areas of human extrastriate visual cortex. The stimuli were single ovals that differed from an implicit standard oval in either colour or width. The subjects’ task was to classify the current stimulus as one of two possible alternatives per stimulus dimension. Three different experimental conditions were conducted: “colour-certainty”, “shape-certainty” and “uncertainty”. In all experimental conditions, the stimulus differed in only one stimulus dimension per trial. In the two certainty conditions, the subjects knew in advance which dimension this would be. During the uncertainty condition they had no such previous knowledge and had to monitor both dimensions simultaneously. Statistical analysis of the fMRI data (with SPM2) revealed a modest effect of the attended stimulus dimension on the neural activity in colour sensitive area V4 (more activity during attention to colour) and in shape sensitive area LOC (more activity during attention to shape). Furthermore, cortical areas known to be related to attention and working memory processes (e.g., lateral prefrontal and posterior parietal cortex) exhibit higher activity during the condition of divided attention (“uncertainty”) than during that of selective attention (“certainty”).
On Diurnal and Annual Variations of Directional Detection Rates of Dark Matter
Creators: name: Bandyopadhyay, Abhijit
name: Majumdar, Debasish
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Direction sensitive direct detection of Weakly Interacting Massive Particles (WIMPs) as dark matter would provide an unambiguous non-gravitational signature of dark matter (DM). The diurnal variation of DM signal due to earth's rotation around its own axis can be a significant signature for galactic WIMPs. Because of particular orientation of earth's axis of rotation with respect to WIMP wind direction, the apparent direction of WIMP wind as observed at a detector can alter widely over a day. In this work we calculate the directional detection rates with their daily and yearly modulations in earth-bound dark matter experiments considering detailed features of the geometry and dynamics of the earth-sun system along with the solar motion in galactic frame. A separate halo model namely the dark disc model other than the usual standard halo model for dark matter halo is also considered and the results for two models are compared. We demonstrate the results for two types of gas detectors namely DRIFT (target material CS2) and NEWAGE (target material CF4) that use Time Projection Chamber techniques for measuring directionality of the recoil nucleus. The WIMP mass and recoil energy dependence of the daily variation of event rates are computed for specific detector and the sensitive ranges of mass and recoil energies for the considered detector are probed.
description: 11 pages, 17 figures
Bootstrap percolation on the random graph $G_{n,p}$
Creators: name: Janson, Svante
name: Łuczak, Tomasz
name: Turova, Tatyana
name: Vallier, Thomas
Publisher: name: arXiv
Year: 2010
Subjects: subject: Probability (math.PR)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics

description: Bootstrap percolation on the random graph $G_{n,p}$ is a process of spread of "activation" on a given realization of the graph with a given number of initially active nodes. At each step those vertices which have not been active but have at least $r\geq2$ active neighbors become active as well. We study the size $A^*$ of the final active set. The parameters of the model are, besides $r$ (fixed) and $n$ (tending to $\infty$), the size $a=a(n)$ of the initially active set and the probability $p=p(n)$ of the edges in the graph. We show that the model exhibits a sharp phase transition: depending on the parameters of the model, the final size of activation with a high probability is either $n-o(n)$ or it is $o(n)$. We provide a complete description of the phase diagram on the space of the parameters of the model. In particular, we find the phase transition and compute the asymptotics (in probability) for $A^*$; we also prove a central limit theorem for $A^*$ in some ranges. Furthermore, we provide the asymptotics for the number of steps until the process stops.
description: Published in at http://dx.doi.org/10.1214/11-AAP822 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Coherent motion pops out during smooth pursuit
Creators: name: Greenlee, Mark W.
name: Schira, Mark M.
name: Kimmig, Hubert
Publisher: name: Universität Regensburg
Year: 2002
Subjects: subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: Stimulus motion is a prominent feature that is used by the visual system to segment figure from ground and perceptually bind widely separated objects. Pursuit eye movements can be influenced by such perceptual grouping processes. We have examined the subjects' ability to detect small amounts of coherent motion in random dot kinematograms during pursuit. We compared performance on tests of coherent motion perception while subjects fixated a stationary spot or while they tracked a moving target. The results indicate that smooth pursuit can improve subjects' ability to detect the presence of coherent motion. We tentatively propose that an efference copy of the eye movement signal can enhance the ability of the visual system to detect correlations between sparsely placed targets among noisy distractors.
Saccadic Suppression of Retinotopically Localized Blood Oxygen Level-Dependent Responses in Human Primary Visual Area V1
Creators: name: Vallines, Ignacio
name: Greenlee, Mark W.
Publisher: name: Universität Regensburg
Year: 2006
Subjects: subject: saccade, vision, cortex, eye movement, fMRI, striate cortex, saccadic suppression, V1, retinotopy
subject: 150 Psychologie
subject: 570 Biowissenschaften, Biologie

description: Saccadic eye movements are responsible for bringing relevant parts of the visual field onto the fovea for detailed analysis. Because the retina is physiologically unable to deliver sharp images at very high transsaccadic speeds, the visual system minimizes the repercussion of the blurry images we would otherwise perceive during transsaccadic vision by reducing general visual sensitivity and increasing the detection threshold for visual stimuli. Ruling out a pure retinal origin, the effects of saccadic suppression can be already observed some 75 ms before the onset of a saccadic eye movement and are maximal at the onset of motion. The perception of a briefly presented stimulus immediately before the onset of any retinal motion is thus impaired despite the fact that this stimulus is projected onto the stationary retina and is, therefore, physically identical to that presented when no saccadic programming is in course. In this functional magnetic resonance imaging event-related study, we flashed Gabor patches at different times before the onset of a horizontal saccade and measured blood oxygen level-dependent responses at their encoding regions in primary visual cortex (V1) while subjects judged the relative orientation of the stimuli. Closely matching the significant reduction in behavioral performance, the amplitude of the responses in V1 consistently decreased as the stimuli were presented closer to the saccadic onset. These results demonstrate that the neural processes underlying saccade programming transiently modulate cortical responses to briefly presented visual stimuli in areas as early a V1, providing additional evidence for the existence of an active saccadic suppression mechanism in humans.