Goos-H\"anchen and Imbert-Fedorov beam shifts: An overview

We consider reflection and transmission of polarized paraxial light beams at a plane dielectric interface. The field transformations taking into account a finite beam width are described based on the plane-wave representation and geometric rotations. Using geometrical-optics coordinate frames accompanying the beams, we construct an effective Jones matrix characterizing spatial-dispersion properties of the interface. This results in a unified self-consistent description of the Goos-H\"anchen and Imbert-Fedorov shifts (the latter being also known as spin-Hall effect of light). Our description reveals intimate relation of the transverse Imbert-Fedorov shift to the geometric phases between constituent waves in the beam spectrum and to the angular momentum conservation for the whole beam. Both spatial and angular shifts are considered as well as their analogues for the higher-order vortex beams carrying intrinsic orbital angular momentum. We also give a brief overview of various extensions and generalizations of the basic beam-shift phenomena and related effects.Comment: 24 pages, 6 figure, to appear in J. Opt. (special issue "Beam shifts"

The first Hochschild cohomology as a Lie algebra

In this paper we study sufficient conditions for the solvability of the first Hochschild cohomology of a finite dimensional algebra as a Lie algebra in terms of its Ext-quiver in arbitrary characteristic. In particular, we show that if the quiver has no parallel arrows and no loops then the first Hochschild cohomology is solvable. For quivers containing loops, we determine easily verifiable sufficient conditions for the solvability of the first Hochschild cohomology. We apply these criteria to show the solvability of the first Hochschild cohomology space for large families of algebras, namely, several families of self-injective tame algebras including all tame blocks of finite groups and some wild algebras including most quantum complete intersections.Comment: 17 pages, v3: substantial rewrit

Stable skyrmions from extra dimensions

We show that skyrmions arising from compact five dimensional models have stable sizes. We numerically obtain the skyrmion configurations and calculate their size and energy. Although their size strongly depends on the magnitude of localized kinetic-terms, their energy is quite model-independent ranging between 50-65 times F_pi^2/m_rho, where F_pi is the Goldstone decay constant and m_rho the lowest Kaluza-Klein mass. These skyrmion configurations interpolate between small 4D YM instantons and 4D skyrmions made of Goldstones and a massive vector boson. Contrary to the original 4D skyrmion and previous 5D extensions, these configurations have sizes larger than the inverse of the cut-off scale and therefore they are trustable within our effective 5D approach. Such solitonic particles can have interesting phenomenological consequences as they carry a conserved topological charge analogous to baryon number.Comment: 20 pages, 3 figure

Out-of-equilibrium tricritical point in a system with long-range interactions

Systems with long-range interactions display a short-time relaxation towards Quasi Stationary States (QSSs) whose lifetime increases with system size. With reference to the Hamiltonian Mean Field (HMF) model, we here show that a maximum entropy principle, based on Lynden-Bell's pioneering idea of "violent relaxation", predicts the presence of out-of-equilibrium phase transitions separating the relaxation towards homogeneous (zero magnetization) or inhomogeneous (non zero magnetization) QSSs. When varying the initial condition within a family of "water-bags" with different initial magnetization and energy, first and second order phase transition lines are found that merge at an out--of--equilibrium tricritical point. Metastability is theoretically predicted and numerically checked around the first-order phase transition line.Comment: Physical Review Letters (2007

Theoretical evidence for efficient p-type doping of GaN using beryllium

Ab initio calculations predict that Be is a shallow acceptor in GaN. Its thermal ionization energy is 0.06 eV in wurtzite GaN; the level is valence resonant in the zincblende phase. Be incorporation is severely limited by the formation of Be_3N_2. We show however that co-incorporation with reactive species can enhance the solubility. H-assisted incorporation should lead to high doping levels in MOCVD growth after post-growth annealing at about 850 K. Be-O co-incorporation produces high Be and O concentrations at MBE growth temperatures.Comment: revised Feb 24 199

Public Hazard, Personal Peril: The Impact of Non-Governmental Organizations in the Environmental Justice Movement

This article argues that the local emphasis of what I call micromovements that form the larger Environmental Justice Movement could gain more traction from relationships with Non-Governmental Organizations. Such partnerships are emerging on a national level; however, since the localized movements communicate with, but are not partners with, national organizations such as the National Black Environmental Network, it is unclear how such partnerships add value to the activities of local groups. Moreover, some partnerships are forged for the organization of a specific event such as a conference or working group study Part II of this article discusses an overview of the history of the Environmental Justice Movement and legal remedies available for environmental justice claims. Part III addresses the partnerships between nongovernmental organizations and grassroots movements focusing specifically on one community\u27s struggle with Velsicol Chemical Corporation. Finally, Part VI discusses the obstacles grassroots movement leaders face in trying to change policy and protect their community and how NGOs can be helpful to these efforts

Are Artificial Tans the New Cigarette? How Plaintiffs Can Use the Lessons of Tobacco Litigation in Bringing Claims Against the Indoor Tanning Industry

Indoor tanning salons have grown significantly in popularity during recent years. Scientific research has revealed a strong link between skin cancer and ultraviolet light exposure from indoor tanning lamps. Despite such dangers, federal regulations place minimal restrictions on the labeling of indoor tanning lamps. Indoor tanning salons work vigorously to dispel notions of a link to skin cancer, often falsely promoting various health benefits of indoor tanning. The first lawsuit for injuries resulting from indoor tanning was recently filed against an indoor tanning salon, and other such litigation is poised to follow. This Note examines three potential tort claims against indoor tanning manufacturers and salons, and suggests ways to formulate compelling arguments in each instance. In doing so it draws on cases finding liability in the context of cigarettes, identifying similarities between the indoor tanning and cigarette industries

Public Hazard, Personal Peril: The Impact of Non-Governmental Organizations in the Environmental Justice Movement

This article argues that the local emphasis of what I call micromovements that form the larger Environmental Justice Movement could gain more traction from relationships with Non-Governmental Organizations. Such partnerships are emerging on a national level; however, since the localized movements communicate with, but are not partners with, national organizations such as the National Black Environmental Network, it is unclear how such partnerships add value to the activities of local groups. Moreover, some partnerships are forged for the organization of a specific event such as a conference or working group study Part II of this article discusses an overview of the history of the Environmental Justice Movement and legal remedies available for environmental justice claims. Part III addresses the partnerships between nongovernmental organizations and grassroots movements focusing specifically on one community\u27s struggle with Velsicol Chemical Corporation. Finally, Part VI discusses the obstacles grassroots movement leaders face in trying to change policy and protect their community and how NGOs can be helpful to these efforts

Metagenomic-based Surveillance of Pacific Coast tick Dermacentor occidentalis Identifies Two Novel Bunyaviruses and an Emerging Human Ricksettsial Pathogen.

An increasing number of emerging tick-borne diseases has been reported in the United States since the 1970s. Using metagenomic next generation sequencing, we detected nucleic acid sequences from 2 novel viruses in the family Bunyaviridae and an emerging human rickettsial pathogen, Rickettsia philipii, in a population of the Pacific Coast tick, Dermacentor occidentalis in Mendocino County sampled annually from 2011 to 2014. A total of 250 adults of this human-biting, generalist tick were collected from contiguous chaparral and grassland habitats, and RNA from each individually extracted tick was deep sequenced to an average depth of 7.3 million reads. We detected a Francisella endosymbiont in 174 ticks (70%), and Rickettsia spp. in 19 ticks (8%); Rickettsia-infected ticks contained R. rhipicephali (16 of 250, 6.4%) or R. philipii (3 of 250,1.2%), the agent of eschar-associated febrile illness in humans. The genomes of 2 novel bunyaviruses (>99% complete) in the genera Nairovirus and Phlebovirus were also identified and found to be present in 20-91% of ticks, depending on the year of collection. The high prevalence of these bunyaviruses in sampled Dermacentor ticks suggests that they may be viral endosymbionts, although further studies are needed to determine whether they are infectious for vertebrate hosts, especially humans, and their potential role in tick ecology