Toroidal Lie superalgebras and free field representations

A loop-algebraic presentation is given for toroidal Lie superalgebras of classical types. Based on the loop superalgebra presentation free field realizations of toroidal Lie superalgebras are constructed for types $A(m,n)$, $B(m,n)$, C(n) and $D(m,n)$.Comment: 23 page

STV-based Video Feature Processing for Action Recognition

In comparison to still image-based processes, video features can provide rich and intuitive information about dynamic events occurred over a period of time, such as human actions, crowd behaviours, and other subject pattern changes. Although substantial progresses have been made in the last decade on image processing and seen its successful applications in face matching and object recognition, video-based event detection still remains one of the most difficult challenges in computer vision research due to its complex continuous or discrete input signals, arbitrary dynamic feature definitions, and the often ambiguous analytical methods. In this paper, a Spatio-Temporal Volume (STV) and region intersection (RI) based 3D shape-matching method has been proposed to facilitate the definition and recognition of human actions recorded in videos. The distinctive characteristics and the performance gain of the devised approach stemmed from a coefficient factor-boosted 3D region intersection and matching mechanism developed in this research. This paper also reported the investigation into techniques for efficient STV data filtering to reduce the amount of voxels (volumetric-pixels) that need to be processed in each operational cycle in the implemented system. The encouraging features and improvements on the operational performance registered in the experiments have been discussed at the end

Lie Superalgebras arising from bosonic representation

A 2-toroidal Lie superalgebra is constructed using bosonic fields and a ghost field. The superalgebra contains $osp(1|2n)^{(1)}$ as a distinguished subalgebra and behaves similarly to the toroidal Lie superalgebra of type $B(0, n)$. Furthermore this algebra is a central extension of the algebra $osp(1|2n)\otimes \mathbb C[s, s^{-1}, t,t^{-1}]$

DMCA Safe Harbors and the Future of New Digital Music Sharing Platforms

SoundCloud is an online service provider that allows users to upload, share, and download music that they have created. It is an innovative platform for both amateur and established producers and disc jockeys (DJs) to showcase their original tracks and remixes. Unfortunately, it is also a platform that lends itself to widespread copyright infringement. Looking toward potential litigation, several factors ought to be considered by SoundCloud and other similar providers. The Viacom v. YouTube case, decided in the Southern District of New York and now currently on appeal in the Second Circuit, sheds light on the potential liability service providers like SoundCloud face. It draws out the Digital Millennium Copyright Act’s (DMCA) safe harbor provisions under which SoundCloud could potentially find protection. However, SoundCloud is unique among similar service providers because it provides users with a variety of viewing, sharing and downloading options that are built into the platform. These options could lead to infringement that would not fall under a DMCA safe harbor. This Issue Brief will discuss the various arguments to be made for and against SoundCloud’s liability, and examine whether the unique utility provided by the service to users could be sustained in the face of potential litigation. Ultimately, the safeguards used by SoundCloud to filter blatant infringement, combined with the DMCA § 512(c) safe harbor, should allow this innovative platform to maintain its current model without neutering its core functionality

Renormalization of trace distance and multipartite entanglement close to the quantum phase transitions of one- and two-dimensional spin-chain systems

We investigate the quantum phase transitions of spin systems in one and two dimensions by employing trace distance and multipartite entanglement along with real-space quantum renormalization group method. As illustration examples, a one-dimensional and a two-dimensional $XY$ models are considered. It is shown that the quantum phase transitions of these spin-chain systems can be revealed by the singular behaviors of the first derivatives of renormalized trace distance and multipartite entanglement in the thermodynamics limit. Moreover, we find the renormalized trace distance and multipartite entanglement obey certain universal exponential-type scaling laws in the vicinity of the quantum critical points

Diffusion and entanglement of a kicked particle in an infinite square well under frequent measurements

We investigate the dynamics of a kicked particle in an infinite square well undergoing frequent measurements of energy. For a large class of periodic kicking force, constant diffusion is found in such a non-KAM system. The influence of phase shift of the kicking potential on the short-time dynamical behavior is discussed. The general asymptotical measurement-assisted diffusion rate is obtained. The entanglement between the particle and the measuring apparatus is investigated. There exist two distinct dynamical behaviors of entanglement. The bipartite entanglement grows with the kicking steps and it gains larger value for the more chaotic system. However, the pairwise entanglement between the system of interest and the partial spins of the measuring apparatus decreases with the kicking steps. The relation between the entanglement and quantum diffusion is also analyzed. PACS numbers: 05.45.Mt, 03.65.TaComment: 7 pages, 5 figures, RevTex4, Accepted by Phys. Rev.

Optimal entanglement generation in cavity QED with dissipation

We investigate a two-level atom coupled to a cavity with a strong classical driving field in a dissipative environment and find an analytical expression of the time evolution density matrix for the system. The analytical density operator is then used to study the entanglement between the atom and cavity by considering the competing process between the atom-field interactions and the field-environment interactions. It is shown that there is an optimal interaction time for generating atom-cavity entanglement.Comment: 9 pages, 7 figure