Young's double slit interference pattern from a twisted beam

The interference pattern of a Laguerre Gaussian beam in a double slit experiment is reported. Whereas a typical laser beam phase front is planar, a Laguerre Gaussian beam exhibits a wave front that is twisting along the direction of propagation. This leads to a distorted interference pattern. The topological charge also called the order of the twisted beam can be then readily and simply determined. More precisely, the naked eye resolution of the distortion shift of the interference pattern directly informs about the number of twists made as well as on the sign of the twist. These results are in very good agreement with theoretical calculations that offer a general description of the double slit interference with twisted beams.Comment: 11 pages, 4 figure

Media interventions and new social imaginaries

Recent re-articulations of the “social imaginary" (Castoriadis 1987) have emerged due to the proliferation and dispersion of new technologies in everyday life. What effect can enacting imaginative narratives for the near future have on present conditions? By reflecting upon two case studies in Serbia (2006) and Montenegro (2009), this paper considers the construction of narrative and spectacle as crafting of social imaginaries. Drawing on participatory, ethnographic and practice-based research methods, these interventions navigate economic and social change by connecting location-based situations with global media networks

Foreword: Critical Race Theory and Empirical Methods Conference

Everyone seems to be talking about race. From the protests that erupted in cities across the country over the failure of grand juries in Missouri and New York to indict police officers in the killing of two unarmed black men, to the racially charged statements made by the owners of professional sports teams; and the college fraternity members captured on film singing a racist lynching song; race exploded into the nation’s collective consciousness. Even the Starbucks Coffee chain’s recent “Race Together” campaign, intended to promote discussion about race, sparked a controversy and was quickly withdrawn. These and other events have propelled race to the top of the national media and policy agendas and made it the topic of dinner table and water cooler conversations throughout the United States. Still, broad disagreement remains, particularly between whites and racial minorities, over what these events mean with respect to contemporary race relations

Beyond Title VII: Rethinking Race, Ex-Offender Status, and Employment Discrimination in the Information Age

More than sixty-five million people in the United States—more than one in four adults—have had some involvement with the criminal justice system that will appear on a criminal history report. A rapidly expanding, for-profit industry has developed to collect these records and compile them into electronic databases, offering employers an inexpensive and readily accessible means of screening prospective employees. Nine out of ten employers now inquire into the criminal history of job candidates, systematically denying individuals with a criminal record any opportunity to gain work experience or build their job qualifications. This is so despite the fact that many individuals with criminal records have never been convicted of a crime, as one-third of felony arrests never result in conviction. And criminal records databases routinely contain significant errors, including false positive identifications and sealed or expunged information. The negative impact of employers’ reliance on criminal records databases falls most heavily on Black and Latino populations, as studies show that the stigma of having a criminal record is significantly more damaging for racial minorities than for Whites. This criminal record “penalty” limits profoundly the chance of achieving gainful employment, creating new and vexing problems for regulators, employers, and minorities with criminal records. Our existing regulatory apparatus, which is grounded in Title VII of the Civil Rights Act of 1964 and the Fair Credit Reporting Act, is ill-equipped to resolve this emerging dilemma because it fails to address systematic information failures and the problem of stigma. This Article, therefore, proposes a new framework drawn from core aspects of anti-discrimination laws that govern health law, notably the Americans with Disabilities Act, and the Genetic Information Nondiscrimination Act. These laws were designed to regulate the flow of information that may form the basis of an adverse employment decision, seeking to prevent discrimination preemptively. More fundamentally, they conceptualize discrimination through the lens of social stigma, which is critical to understanding and prophylactically curbing the particular discrimination that results from dual criminal record and minority status. This health law framework attends to the interests of minorities with criminal records, allows for more robust enforcement of existing laws, and enables employers to make appropriate and equitable hiring decisions, without engaging in invidious discrimination or contributing to the establishment of a new, and potentially enduring, underclass

Kirillov's orbit method: the case of discrete series representations

Let V be an Harish-Chandra discrete series representation of a real semi-simple Lie group G' and let G be a semi-simple subgroup of G'. In this paper, we give a geometric expression of the G-multiplicities in V when the representation V is supposed to be G-admissible

Notes on Mayer Expansions and Matrix Models

Mayer cluster expansion is an important tool in statistical physics to evaluate grand canonical partition functions. It has recently been applied to the Nekrasov instanton partition function of $\mathcal{N}=2$ 4d gauge theories. The associated canonical model involves coupled integrations that take the form of a generalized matrix model. It can be studied with the standard techniques of matrix models, in particular collective field theory and loop equations. In the first part of these notes, we explain how the results of collective field theory can be derived from the cluster expansion. The equalities between free energies at first orders is explained by the discrete Laplace transform relating canonical and grand canonical models. In a second part, we study the canonical loop equations and associate them to similar relations on the grand canonical side. It leads to relate the multi-point densities, fundamental objects of the matrix model, to the generating functions of multi-rooted clusters. Finally, a method is proposed to derive loop equations directly on the grand canonical model.Comment: 24 pages, 8 figures, v2: references added, published in NP