Anomalous Chiral Action from the Path-Integral

By generalizing the Fujikawa approach, we show in the path-integral formalism: (1) how the infinitesimal variation of the fermion measure can be integrated to obtain the full anomalous chiral action; (2) how the action derived in this way can be identified as the Chern-Simons term in five dimensions, if the anomaly is consistent; (3) how the regularization can be carried out, so as to lead to the consistent anomaly and not to the covariant anomaly. Our method uses Schwinger's ``proper-time'' representation of the Green's function and the gauge invariant point-splitting technique. We find that the consistency requirement and the point-splitting technique allow both an anomalous and a non-anomalous action. In the end, the nature of the vacuum determines whether we have an anomalous theory, or, a non-anomalous theoryComment: 28 page

Enhanced cell visiting probability for QoS provisioning in mobile multimedia communications

This paper presents an enhanced cell visiting probability (CVP) estimation technique by integrating both mobility parameters such as position, direction, and speed together with exponential call duration probability of mobile units. These improved CVP estimates can be used in both adaptive and nonadaptive mobile networks to enhance QoS parameters. This paper also presents a new shadow-clustering scheme based on these enhanced CVPs, which is then applied to the call admission control scheme similar to the one, called predictive mobility support QoS provisioning scheme, proposed by Aljadhai and Znati (2001). Simulation results confirm that this new shadow-clustering scheme outperforms predictive mobility support QoS provisioning scheme in terms of different QoS parameters under various different traffic conditions

Surgical-VQLA:Transformer with Gated Vision-Language Embedding for Visual Question Localized-Answering in Robotic Surgery

Despite the availability of computer-aided simulators and recorded videos of surgical procedures, junior residents still heavily rely on experts to answer their queries. However, expert surgeons are often overloaded with clinical and academic workloads and limit their time in answering. For this purpose, we develop a surgical question-answering system to facilitate robot-assisted surgical scene and activity understanding from recorded videos. Most of the existing visual question answering (VQA) methods require an object detector and regions based feature extractor to extract visual features and fuse them with the embedded text of the question for answer generation. However, (i) surgical object detection model is scarce due to smaller datasets and lack of bounding box annotation; (ii) current fusion strategy of heterogeneous modalities like text and image is naive; (iii) the localized answering is missing, which is crucial in complex surgical scenarios. In this paper, we propose Visual Question Localized-Answering in Robotic Surgery (Surgical-VQLA) to localize the specific surgical area during the answer prediction. To deal with the fusion of the heterogeneous modalities, we design gated vision-language embedding (GVLE) to build input patches for the Language Vision Transformer (LViT) to predict the answer. To get localization, we add the detection head in parallel with the prediction head of the LViT. We also integrate generalized intersection over union (GIoU) loss to boost localization performance by preserving the accuracy of the question-answering model. We annotate two datasets of VQLA by utilizing publicly available surgical videos from EndoVis-17 and 18 of the MICCAI challenges. Our validation results suggest that Surgical-VQLA can better understand the surgical scene and localized the specific area related to the question-answering. GVLE presents an efficient language-vision embedding technique by showing superior performance over the existing benchmarks

Quantum temporal correlations and entanglement via adiabatic control of vector solitons

It is shown that optical pulses with a mean position accuracy beyond the standard quantum limit can be produced by adiabatically expanding an optical vector soliton followed by classical dispersion management. The proposed scheme is also capable of entangling positions of optical pulses and can potentially be used for general continuous-variable quantum information processing.Comment: 5 pages, 1 figure, v2: accepted by Physical Review Letters, v3: minor editing and shortening, v4: included the submitted erratu

Comparison of auctions and alternative policy options for RES-E support

This is the final version of the report. Available from AURES via the DOI in this record.This report summarises the findings of Task 6.2 of the AURES project. It intends to compare auctions with alternative policy instruments and examines under which circumstances auctions may be superior and inferior to achieve intended policy targets. Among an abundant list of potential policy drivers, which may affect an instrument’s effectiveness, its efficiency or further success criteria, the basis for the present analysis is the factor risk. It is demonstrated that risk constitutes an important factor as it may have decisive effects on societal welfare and thus may affect the decision-making of policy makers. Given a degree of uncertainty regarding the marginal costs and the marginal benefits of renewable support, particularly the choice between price and quantity-based instruments may yield different welfare effects. Both instruments expose policy makers to a risk of setting inefficient investment incentives. However, while price instruments may reduce the risk of welfare losses given a relatively steep marginal cost and a comparably flat marginal benefit curve, a quantity scheme may be superior if the relation between the two curves is vice versa. Building on this insight, our analysis reveals that the incentives for the use of policy instruments to support the deployment of RES are both country and technology specific. In general, it appears that the incentive to employ a quantity-based mean such as an auction is larger when the natural resources of the technology that is to be supported are abundant and if that technology is rather well developed. Moreover, since within a country the market and natural conditions of the different RES technologies and hence their supply costs may vary considerably, our findings provide an argument against a technology-neutral support.EU Horizon 2020 program, grant number 64617

Evolution of antiferromagnetic domains in the all-in-all-out ordered pyrochlore Nd2_2Zr2_2O7_7

We report the observation of magnetic domains in the exotic, antiferromagnetically ordered all-in-all-out state of Nd$_2$Zr$_2$O$_7$, induced by spin canting. The all-in-all-out state can be realized by Ising-like spins on a pyrochlore lattice and is established in Nd$_2$Zr$_2$O$_7$ below 0.31 K for external magnetic fields up to 0.14 T. Two different spin arrangements can fulfill this configuration which leads to the possibility of magnetic domains. The all-in-all-out domain structure can be controlled by an external magnetic field applied parallel to the [111] direction. This is a result of different spin canting mechanism for the two all-in-all-out configurations for such a direction of the magnetic field. The change of the domain structure is observed through a hysteresis in the magnetic susceptibility. No hysteresis occurs, however, in case the external magnetic field is applied along [100].Comment: Accepted for publication in Phys. Rev. B, 6 pages, 6 figure

Rotated stripe order and its competition with superconductivity in La1.88_{1.88}Sr0.12_{0.12}CuO4_4

We report the observation of a bulk charge modulation in La$_{1.88}$Sr$_{0.12}$CuO$_4$ (LSCO) with a characteristic in-plane wave-vector of (0.236, $\pm \delta$), with $\delta$=0.011 r.l.u. The transverse shift of the ordering wave-vector indicates the presence of rotated charge-stripe ordering, demonstrating that the charge ordering is not pinned to the Cu-O bond direction. On cooling through the superconducting transition, we find an abrupt change in the growth of the charge correlations and a suppression of the charge order parameter indicating competition between the two orderings. Orthorhombic LSCO thus helps bridge the apparent disparities between the behavior previously observed in the tetragonal "214" cuprates and the orthorhombic yttrium and bismuth-based cuprates and thus lends strong support to the idea that there is a common motif to charge order in all cuprate families.Comment: 6 pages, 4 figue

Spinon confinement in a quasi one dimensional anisotropic Heisenberg magnet

Confinement is a process by which particles with fractional quantum numbers bind together to form quasiparticles with integer quantum numbers. The constituent particles are confined by an attractive interaction whose strength increases with increasing particle separation and as a consequence, individual particles are not found in isolation. This phenomenon is well known in particle physics where quarks are confined in baryons and mesons. An analogous phenomenon occurs in certain magnetic insulators; weakly coupled chains of spins S=1/2. The collective excitations in these systems is spinons (S=1/2). At low temperatures weak coupling between chains can induce an attractive interaction between pairs of spinons that increases with their separation and thus leads to confinement. In this paper, we employ inelastic neutron scattering to investigate the spinon confinement in the quasi-1D S=1/2 XXZ antiferromagnet SrCo2V2O8. Spinon excitations are observed above TN in quantitative agreement with established theory. Below TN the pairs of spinons are confined and two sequences of meson-like bound states with longitudinal and transverse polarizations are observed. Several theoretical approaches are used to explain the data. A new theoretical technique based on Tangent-space Matrix Product States gives a very complete description of the data and provides good agreement not only with the energies of the bound modes but also with their intensities. We also successfully explained the effect of temperature on the excitations including the experimentally observed thermally induced resonance between longitudinal modes below TN ,and the transitions between thermally excited spinon states above TN. In summary, our work establishes SrCo2V2O8 as a beautiful paradigm for spinon confinement in a quasi-1D quantum magnet and provides a comprehensive picture of this process.Comment: 17 pages, 18 figures, submitted to PR

Evolutionary quantum cosmology in a gauge-fixed picture

We study the classical and quantum models of a flat Friedmann-Robertson-Walker (FRW) space-time, coupled to a perfect fluid, in the context of the consensus and a gauge-fixed Lagrangian frameworks. It is shown that, either in the usual or in the gauge-fixed actions, the evolution of the universe based on the classical cosmology represents a late time power law expansion, coming from a big-bang singularity in which the scale factor goes to zero for the standard matter, and tending towards a big-rip singularity in which the scale factor diverges for the phantom fluid. We then employ the familiar canonical quantization procedure in the given cosmological setting to find the cosmological wave functions in the corresponding minisuperspace. Using a gauge-fixed (reduced) Lagrangian, we show that, it may lead to a Schr\"{o}dinger equation for the quantum-mechanical description of the model under consideration, the eigenfunctions of which can be used to construct the time dependent wave function of the universe. We use the resulting wave function in order to investigate the possibility of the avoidance of classical singularities due to quantum effects by means of the many-worlds and ontological interpretation of quantum cosmology.Comment: 15 pages, 10 figures, typos corrected, Refs. adde