Quantum anomaly of the transverse Ward-Takahashi relation for the axial-vector vertex

We study the possible quantum anomaly for the transverse Ward-Takahashi relations in four dimensional gauge theories based on the method of computing the axial-vector and the vector current operator equations. In addition to the well-known anomalous axial-vector divergence equation (the Adler-Bell-Jackiw anomaly), we find the anomalous axial-vector curl equation, which leads to the quantum anomaly of the transverse Ward-Takahashi relation for the axial-vector vertex. The computation shows that there is no anomaly for the transverse Ward-Takahashi relation for the vector vertex.Comment: 6 pages, LaTe

Boosting Moving Object Indexing through Velocity Partitioning

There have been intense research interests in moving object indexing in the past decade. However, existing work did not exploit the important property of skewed velocity distributions. In many real world scenarios, objects travel predominantly along only a few directions. Examples include vehicles on road networks, flights, people walking on the streets, etc. The search space for a query is heavily dependent on the velocity distribution of the objects grouped in the nodes of an index tree. Motivated by this observation, we propose the velocity partitioning (VP) technique, which exploits the skew in velocity distribution to speed up query processing using moving object indexes. The VP technique first identifies the "dominant velocity axes (DVAs)" using a combination of principal components analysis (PCA) and k-means clustering. Then, a moving object index (e.g., a TPR-tree) is created based on each DVA, using the DVA as an axis of the underlying coordinate system. An object is maintained in the index whose DVA is closest to the object's current moving direction. Thus, all the objects in an index are moving in a near 1-dimensional space instead of a 2-dimensional space. As a result, the expansion of the search space with time is greatly reduced, from a quadratic function of the maximum speed (of the objects in the search range) to a near linear function of the maximum speed. The VP technique can be applied to a wide range of moving object index structures. We have implemented the VP technique on two representative ones, the TPR*-tree and the Bx-tree. Extensive experiments validate that the VP technique consistently improves the performance of those index structures.Comment: VLDB201

A Note on Transverse Axial Vector and Vector Anomalies in U(1) Gauge Theories

The transverse axial vector and vector anomalies in four-dimensional U(1) gauge theories studied in [10] is reexamined by means of perturbative methods. The absence of transverse anomalies for both axial vector and vector current is verified. We also show that the Pauli-Villars regularization and dimensional regularization give the same result on the transverse anomaly of both axial vector and vector current.Comment: Revtex4, 8 pages, two figures. Largely revised, using the Pauli-Villars regularization instead of dimensional regularization in the main proof. Final form to be published in Physics Letters

Movement-related beta oscillations show high intra-individual reliability

Oscillatory activity in the beta frequency range (15-30Hz) recorded from human sensorimotor cortex is of increasing interest as a putative biomarker of motor system function and dysfunction. Despite its increasing use in basic and clinical research, surprisingly little is known about the test-retest reliability of spectral power and peak frequency measures of beta oscillatory signals from sensorimotor cortex. Establishing that these beta measures are stable over time in healthy populations is a necessary precursor to their use in the clinic. Here, we used scalp electroencephalography (EEG) to evaluate intra-individual reliability of beta-band oscillations over six sessions, focusing on changes in beta activity during movement (Movement-Related Beta Desynchronization, MRBD) and after movement termination (Post-Movement Beta Rebound, PMBR). Subjects performed visually-cued unimanual wrist flexion and extension. We assessed Intraclass Correlation Coefficients (ICC) and between-session correlations for spectral power and peak frequency measures of movement-related and resting beta activity. Movement-related and resting beta power from both sensorimotor cortices was highly reliable across sessions. Resting beta power yielded highest reliability (average ICC=0.903), followed by MRBD (average ICC=0.886) and PMBR (average ICC=0.663). Notably, peak frequency measures yielded lower ICC values compared to the assessment of spectral power, particularly for movement-related beta activity (ICC=0.386-0.402). Our data highlight that power measures of movement-related beta oscillations are highly reliable, while corresponding peak frequency measures show greater intra-individual variability across sessions. Importantly, our finding that beta power estimates show high intra-individual reliability over time serves to validate the notion that these measures reflect meaningful individual differences that can be utilised in basic research and clinical studies

Personal Information Interfaces

poster abstractAs the ubiquitous computing vision of “computation everywhere” has become increasingly mainstream, people make use of electronic information across multiple form factors, in more places, as part of more activities, and in more social contexts than ever before. This is the crux of the information overload problem: with a vast increase in exposure to information, there is a corresponding increase in the amount of work that people need to invest to keep up with the demands of perceiving, sense-making, organizing, utilizing, and managing that information. Dr. Stephen Voida and his student researchers in the Personal Information Interfaces (PII) laboratory explore ways that the interfaces, interaction techniques, and context-aware infrastructure employed in the next generation of information systems might better respond to the critical, real-world challenges associated with information overload. A new generation of sensor-enabled computing devices stands to magnify the information overload effect by adding streams of data about our environment, our working contexts, and traces of our activities—both online and in the real world—into the mix. A popular example is the growing number of fitness tracking devices that have appeared on the market in the last few years, for example, Fitbits, Nike+ Fuelbands, and the Jawbone Up (just to name a few). Proponents of the “quantified self” movement suggest one way to use the data streams provided by these devices: as a means for self-reflection. However, effective self-reflection requires that a vast amount of information—often highly personal in nature—be captured by our devices, and it introduces new work for end-users, such as finding patterns in the data and translating sensed trends into effective actions. We are currently launching a study of commercial fitness trackers to understand when different representations of self-reflective data streams are effective in helping to facilitate behavior change…and when those representations contribute instead to a sense of information overload. We are also exploring similar questions related to other technologies that collect and present self-reflective data about daily life—time management tools, mood-tracking apps, and the like. In general, we aim to understand how infrastructure and interface design can prevent people’s experiences of sensed data streams from contributing to information overload while still allowing us to capitalize on the positive behavior change and self-reflection potential of this information

Radiative Corrections to W^+W^- \to W^+W^- in the Electroweak Standard Model

The cross-section for W^+W^- \to W^+W^- with arbitrarily polarized W bosons is calculated within the Electroweak Standard Model including the complete virtual and soft-photonic O(alpha) corrections. We show the numerical importance of the radiative corrections for the dominating polarized cross-sections and for the unpolarized cross-section. The numerical accuracy of the equivalence theorem is investigated in O(alpha) by comparing the cross-section for purely longitudinal W bosons obtained from the equivalence theorem and from the direct calculation. We point out that the instability of the W boson, which is inherent in the one-loop corrections, prevents a consistent calculation of radiative corrections to the scattering of on-real-mass-shell longitudinal W bosons beyond O(alpha).Comment: 24 pages, LaTeX, uses axodraw, epsfig. Statement clarifie

A supervised clustering approach for fMRI-based inference of brain states

We propose a method that combines signals from many brain regions observed in functional Magnetic Resonance Imaging (fMRI) to predict the subject's behavior during a scanning session. Such predictions suffer from the huge number of brain regions sampled on the voxel grid of standard fMRI data sets: the curse of dimensionality. Dimensionality reduction is thus needed, but it is often performed using a univariate feature selection procedure, that handles neither the spatial structure of the images, nor the multivariate nature of the signal. By introducing a hierarchical clustering of the brain volume that incorporates connectivity constraints, we reduce the span of the possible spatial configurations to a single tree of nested regions tailored to the signal. We then prune the tree in a supervised setting, hence the name supervised clustering, in order to extract a parcellation (division of the volume) such that parcel-based signal averages best predict the target information. Dimensionality reduction is thus achieved by feature agglomeration, and the constructed features now provide a multi-scale representation of the signal. Comparisons with reference methods on both simulated and real data show that our approach yields higher prediction accuracy than standard voxel-based approaches. Moreover, the method infers an explicit weighting of the regions involved in the regression or classification task

<i>Schizosaccharomyces pombe</i> Pol II transcription elongation factor ELL functions as part of a rudimentary super elongation complex

ELL family transcription factors activate the overall rate of RNA polymerase II (Pol II) transcription elongation by binding directly to Pol II and suppressing its tendency to pause. In metazoa, ELL regulates Pol II transcription elongation as part of a large multisubunit complex referred to as the Super Elongation Complex (SEC), which includes P-TEFb and EAF, AF9 or ENL, and an AFF family protein. Although orthologs of ELL and EAF have been identified in lower eukaryotes including Schizosaccharomyces pombe, it has been unclear whether SEClike complexes function in lower eukaryotes. In this report, we describe isolation from S. pombe of an ELL-containing complex with features of a rudimentary SEC. This complex includes S. pombe Ell1, Eaf1, and a previously uncharacterized protein we designate Ell1 binding protein 1 (Ebp1), which is distantly related to metazoan AFF family members. Like the metazoan SEC, this S. pombe ELL complex appears to function broadly in Pol II transcription. Interestingly, it appears to have a particularly important role in regulating genes involved in cell separation