4,248 research outputs found
Quantum field theory on the Bertotti-Robinson space-time
We consider the problem of quantum field theory on the Bertotti-Robinson
space-time, which arises naturally as the near horizon geometry of an extremal
Reissner-Nordstrom black hole but can also arise in certain near-horizon limits
of non-extremal Reissner Nordstrom space-time. The various vacuum states have
been considered in the context of black holes by Spradlin and
Strominger who showed that the Poincare vacuum, the Global vacuum and the
Hartle-Hawking vacuum are all equivalent, while the Boulware vacuum and the
Schwarzschild vacuum are equivalent. We verify this by explicitly computing the
Green's functions in closed form for a massless scalar field corresponding to
each of these vacua. Obtaining a closed form for the Green's function
corresponding to the Boulware vacuum is non-trivial, we present it here for the
first time by deriving a new summation formula for associated Legendre
functions that allows us to perform the mode-sum. Having obtained the
propagator for the Boulware vacuum, which is a zero-temperature Green's
function, we can then consider the case of a scalar field at an arbitrary
temperature by an infinite image imaginary-time sum, which yields the
Hartle-Hawking propagator upon setting the temperature to the Hawking
temperature. Finally, we compute the renormalized stress-energy tensor for a
massless scalar field in the various quantum vacua.Comment: 15 pages, to be published in PR
Vacuum Polarization on the Schwarzschild Metric with a Cosmic String
We consider the problem of the renormalization of the vacuum polarization in
a symmetry space-time with axial but not spherical symmetry, Schwarzschild
space-time threaded by an infinite straight cosmic string. Unlike previous
calculations, our framework to compute the renormalized vacuum polarization
does not rely on special properties of Legendre functions, but rather has been
developed in a way that we expect to be applicable to Kerr space-time
Blood in the Water: Salvadoran Rivers of Testimony and Resistance
From the 1970s to the early 1990s the dominant forms of literary production in El Salvador, Guatemala, and Nicaragua were testimonial literature and literature of resistance. During this time period, all three of these Central American countries were embroiled in bloody civil wars, and the written word was employed on the cultural front as a means of denouncing and resisting various forms of oppression. For both historical and artistic reasons, rivers frequently play an important role in cultural production from and about this era and have thus become embedded in the complex web of ideological signifiers that comprises the discursive practices of Central American literature
Attentional style of soccer athletes
A test of soccer attentional style (TSAS) was designed, based upon six attentional constructs utilized by Nideffer in the Test of Attentional and Interpersonal Style (TAIS). Both tests were administered, together with a personal assessment questionnaire (PAQ) for self-report measures of ability, success, and experience in soccer.
[This is an excerpt from the abstract. For the complete abstract, please see the document.
Inverting the Discourse of Civilization and Barbarism in \u3cem\u3eMundo del Fin del Mundo\u3c/em\u3e and \u3cem\u3eUn Viejo que LeĂa Novelas de Amor\u3c/em\u3e by Luis SepĂșlveda
American critic Raymond Leslie Williams has convincingly argued that a desire to be modern is a central characteristic of the 20th century Latin American novel. Williams\u27s argument also coincides with Octavio Paz\u27s assertion that modernity has been a topic of interest to Latin American intellectuals since the 19th century. A glimpse of the terminology used by authors and critics to name various Latin American movements over the past 125 yearsâmodernismo, posmodernismo, avant-garde, modern novel, and postmodern fictionâgives us a sense of the persistent desire of Latin American authors to engage in a dialogue on Latin American subjectsâ positions within modernity. Since the 1990s, a corpus of works has emerged in Latin America that suggests that it is already possible to speak of the environmental novel as an authentic subgenre of Latin American fiction. The development of the Latin American environmental novel can be understood as a further manifestation of the historical desire of Latin American intellectuals to engage with the concept of modernity. This new subgenre arises in the context of an order of global neocolonialism in which the authors elaborate counter-discourses to the economic models of modernity that have frequently been imposed by wealthy nations. In the present essay, I offer readings of two environmental novels by Chilean novelist Luis SepĂșlvedaâUn viejo que leĂa novelas de amor (1989) and Mundo del fin del mundo (1989)âas examples of the Latin American environmental novelâs engagement with the concept of modernity. Specifically, I analyze how SepĂșlvedaâs novels undermine the Eurocentric notion of modernity proffered by Domingo Faustino Sarmiento in his 1845 treatise CivilizaciĂłn y barbarie o vida de Juan Facundo Quiroga. Ultimately, I argue that SepĂșlvedaâs ironic inversion of Sarmientoâs concept of civilization and barbarism can be understood as a decolonial gesture
Investigating Vection Responses in Patients with Early Stage Glaucoma
Purpose: Our lab has previously shown that patients with early glaucoma have dysfunctional vection responses. We attempted to explain this finding using a combined index of structure and function (CSFI), originally proposed by Medeiros et al. (OVS 2012;130(9):1107-1116)
Methods: Roll and circular vection were evoked using a back projected screen (Experiment 1) and the Oculus RiftTM system (Experiment 2), respectively. The CSFI, was obtained using clinical data from visual field tests and optical coherence tomography.
Results: In Experiment 1, the log of vection latency was significantly longer for patients with glaucoma (t(21) = 2.39, p < .05). In Experiment 2, vection latency was significantly longer for the glaucoma group for both stimulus speeds (F(1,22) = 6.38, p = .019). However, the CSFI was not related to vection latency, duration, or rating (smallest p = .06).
Conclusion: In two different studies we replicated the finding that vection responses are longer in patients with glaucoma; however, the CSFI is not related to vection responses
US Central American Identities in Roberto Quesadaâs \u3cem\u3eBig Banana\u3c/em\u3e and \u3cem\u3eNunca Entres por Miami\u3c/em\u3e
Following several calls in recent scholarship for increased attention to the study of the Central American diaspora in the United States, this article offers readings of Honduran-born author Roberto Quesadaâs novels Big Banana (1999) and Nunca entres por Miami (2003). Written in New York City, where he has resided since 1989, Big Banana highlights issues of Central American identity, migration, and immigrant experiences. Published four years later, Nunca entres por Miami continues to engage with these important topics. My readings of Quesadaâs novels focus on the ways in which they construct cultural memory and identity by providing critical historical context that is absent from most mass media coverage of Central American migration to the United States. By engaging with theoretical constructions of Latinidad, this article also analyzes the ways in which Quesadaâs characters represent the multi-layered and intersectional nature of US Central American identities. Ultimately, I posit that these novels make a move towards establishing the identity politics that critics such as Arturo Arias assert will be necessary for US Central Americans to emerge as a unique, recognizable, and influential entity in the multicultural landscape of the United States in the twenty-first century
A qualitative perspective on multiple health behaviour change: views of smoking cessation advisors who promote physical activity
There are mixed views on whether smoking cessation advisors should focus only on quitting smoking or also promote simultaneous health behaviour changes (e.g. diet, physical activity), but no studies have qualitatively examined the views and vicarious experiences of such health professionals. Semi-structured interviews were conducted with 11 trained smoking cessation advisors who promote physical activity to their clients. The data were categorised into themes using thematic analysis supported by qualitative data analysis software. We report themes that were related to why advisors promote multiple health behaviour change and issues in timing. Physical activity could be promoted as a cessation aid and also as part of a holistic lifestyle change consistent with a non-smoker identity, thereby increasing feelings of control and addressing fear of weight gain. Multiple changes were promoted pre-quit, simultaneously and post-quit, and advisors asserted that it is important to focus on the needs and capabilities of individual clients when deciding how to time multiple changes. Also, suggesting that PA was a useful and easily performed cessation aid rather than a new behaviour (i.e. structured exercise that may seem irrelevant) may help some clients to avoid a sense of overload
Determinants of physical activity promotion by smoking cessation advisors as an aid for quitting: Support for the Transtheoretical Model
Objectives: Physical activity (PA) can reduce cigarette cravings and aid quitting but little is known about its promotion by smoking cessation advisors. This study aimed to: (1) determine the extent to which smoking cessation advisors promote PA; and (2) examine the relationship between PA promotion as a cessation aid and advisor characteristics and cognitions, within the Transtheoretical
Model (TM) framework.
Methods: Self-report surveys assessing PA promotion, TM variables, advisorsâ own PA levels and demographics were completed by 170 advisors in England and Scotland.
Results: Advisors reported spending 29 minutes promoting PA over a 6/7-week clinic. Those in later stages of readiness for promoting PA as a cessation aid and those spending more time promoting PA held more positive beliefs regarding pros and cons, self-efficacy, outcome efficacy and importance
of PA within smoking cessation. Time spent promoting PA and stage of readiness were strongly associated. There was a trend for the more physically active advisors to promote PA more often.
Conclusions: About half the advisors promoted PA and TM variables predicted this variability.
Practice Implications: PA promotion among smoking cessation advisors may be facilitated by enhancing self-efficacy, outcome efficacy and pro and con-beliefs related to PA promotion
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