Symmetry characterization of the collective modes of the phase diagram of the ν=0\nu=0 quantum Hall state in graphene: Mean-field and spontaneously broken symmetries

We devote this work to the study of the mean-field phase diagram of the $\nu=0$ quantum Hall state in bilayer graphene and the computation of the corresponding neutral collective modes, extending the results of recent works in the literature. Specifically, we provide a detailed classification of the complete orbital-valley-spin structure of the collective modes and show that phase transitions are characterized by singlet modes in orbital pseudospin, which are independent of the Coulomb strength and suffer strong many-body corrections from short-range interactions at low momentum. We describe the symmetry breaking mechanism for phase transitions in terms of the valley-spin structure of the Goldstone modes. For the remaining phase boundaries, we prove that the associated exact $SO(5)$ symmetry existing at zero Zeeman energy and interlayer voltage survives as a weaker mean-field symmetry of the Hartree-Fock equations. We extend the previous results for bilayer graphene to the monolayer scenario. Finally, we show that taking into account Landau level mixing through screening does not modify the physical picture explained above.Comment: 44 pages, 10 figure

Has long become longer or short become shorter? Evidence from a censored quantile regression analysis of the changes in the distribution of U.S. unemployment duration

There is conflicting evidence regarding the recent evolution of unemployment duration in the U.S. In this study we rely on censored quantile regression methods to analyze the changes in the US unemployment duration distribution. We employed the decomposition method proposed by Machado and Mata (2003) to disentangle the contribution of the changes generated by the covariate distribution and by the conditional distribution and adapted it to a duration analysis framework.The data used in this inquiry are taken from the nationally representative Displaced Worker Survey of 1988 and 1998. We provide evidence that the unemployment duration distribution shifted leftward. The main driving force behind that shift was the sharp leftward move in the unemployment rate distribution. This force was partially counteracted by the ageing of the displaced population, the striking absence of impact from being displaced via a plant shutdown, and the higher sensitivity of unemployment duration to unemployment ratesQuantile Regression, Duration Analysis, Unemployment Duration, Counterfactual Decomposition

Violation of Cauchy-Schwarz inequalities by spontaneous Hawking radiation in resonant boson structures

The violation of a classical Cauchy-Schwarz (CS) inequality is identified as an unequivocal signature of spontaneous Hawking radiation in sonic black holes. This violation can be particularly large near the peaks in the radiation spectrum emitted from a resonant boson structure forming a sonic horizon. As a function of the frequency-dependent Hawking radiation intensity, we analyze the degree of CS violation and the maximum violation temperature for a double barrier structure separating two regions of subsonic and supersonic condensate flow. We also consider the case where the resonant sonic horizon is produced by a space-dependent contact interaction. In some cases, CS violation can be observed by direct atom counting in a time-of-flight experiment. We show that near the conventional zero-frequency radiation peak, the decisive CS violation cannot occur.Comment: 10 pages, 6 figure

On Freezing Effects

This paper discusses the nature of Rizzi’s (2006, 2007) Criterial Freezing, a mechanism yielding island effects on XPs moving into edge positions within the Left Periphery to satisfy dedicated ‚criteria‛. Contrary to Rizzi’s (2006) feature checking implementation, it is claimed that freezing, as originally outlined in Chomsky (2000, 2001) Probe-Goal framework, is restricted to purely formal features of the Case/agreement systems, criterial formatives (e.g., [topic], [focus], [wh]) being irrelevant for minimality purposes. Consequently, it is argued that Criterial Freezing is best regarded as an interface constraint precluding XPs from being assigned multiple interpretations of the same type, for legibility/convergence reasons ultimately related to the Principle of Full Interpretation.Este trabajo aborda la naturaleza del proceso de Inmovilización de Criterio establecido por Rizzi, un mecanismo que reivindica Efectos de isla por parte de aquellos SSXX que se mueven a una posición de arista dentro de la periferia izquierda para de esta forma satisfacer ‘criterios’ específicos. A diferencia de la implementación llevada a cabo por Rizzi en su teoría de validación de rasgos, se establece que la operación de Inmovilización, tal y como se concibe inicialmente en el marco de trabajo Sonda-Meta de Chomsky (2000, 2001) está limitado a rasgos puramente formales de los sistemas de Caso/concordancia, por lo que los formativos de criterio (por ejemplo, [tópico], [foco], [wh]) son irrelevantes desde un punto de vista minimalista. Por lo tanto, se establece que el proceso de Inmovilización de Criterio ha de ser considerado como una limitación propia de la interfaz que evita que los SSXX reciban interpretaciones múltiples del mismo tipo, debiéndose en última instancia a razones de legibilidad/convergencia relacionadas con el Principio de Interpretación Plena.Este artigo discute a natureza do Congelamento Criterial de Rizzi (2006, 2007), um mecanismo que produz efeitos de ilha em XPs deslocados para posições periféricas dentro da Periferia à Esquerda para satisfação de «critérios» dedicados. Contrariamente à implementação da propriedade de verificação de Rizzi (2006), afirma-se que o congelamento (como originalmente concebido em Chomsky (2000, 2001) quadro Sonda-Alvo restringe-se a propriedades puramente formais dos sistemas de Caso/concordância, sendo formativos criteriais (por exemplo, [tópico], [foco], [wh-]) irrelevantes para fins de minimalidade. Consequentemente, é argumentado que o Congelamento Criterial é melhor concebido como um interface de restrição impedindo a atribuição de múltiplas interpretações do mesmo tipo a XPs, por razões de legitimidade/convergência relacionadas em última instância com o Princípio da Interpretação Plena

Dynamic Workplace Design

The design of workplaces is often complex because it balances two opposing forces: on the one hand, innovation and creativity often involve teamwork processes and collaboration, occurring in spaces which may then produce higher than normal noise levels. On the other hand, many work processes rely on individual work, which requires quiet spaces needed for concentration. Another complex issues that office design architects must address involves the ever changing nature of workplaces, either as part of short-term evolving daily activities or as part of the longer-term changes organizations have to bring to their managerial style in order to stay competitive and productive. This thesis proposes an experimental methods of improving acoustic properties in open-plan offices using a two-fold approach: specific tailoring of acoustic panels and other devices used in as needed bases; and the arrangement of office layouts to better match the managerial profile of organizations in terms of autonomy and interaction. This thesis develops and tests the hypothesis that the balance of visual connectivity and auditory privacy in the workplace through the creation of organized sound composing a focus-driven atmosphere will improve the efficiency of the collaborative workplace and its environment. By observing in detail the elements of sound, materiality and effective experimenting, the thesis incorporates a process allowing for the control of the sound in the workplace, and thus encouraging higher productivity in the office space. By studying an open office space that can offer surfaces it determines modifications depending on the qualities of the room. The open office must become a culture that can identify the issues within its wall and the most effective way to contra rest the loose of focus. The goal is to improve the process in which architecture creates a better functional office space for people to use. By referencing back to past work this thesis tackles this issue using tools and by gathering information from past attempts and precedents. Building a strong backbone for this process to work is key for the future investigation to endure. This thesis develops the argument that introduces sound into architecture as the main goal. To better demonstrate the purpose of the thesis experiments that measures sound physically in the environment will be simulated and analyzed with digital tools that design into an existing space. The analyzed space is specifically an office space that way the result provides structure for the theorem and concept. The expected results are analyzed in order to prove that acoustic design is a major factor and it improves the efficiency in the workplace without disregarding visual connectivity