DISCUSSION PAPER: PARTICLE CREATION BY GRAVITATIONAL FIELDS

It is well known that not every symmetry of a classical field theory is also a symmetry of its quantum version. When this occurs, we speak of quantum anomalies. The existence of anomalies imply that some classical Noether charges are no longer conserved in the quantum theory. In this paper, we discuss a new example for quantum electromagnetic fields propagating in the presence of gravity. We argue that the symmetry under electric-magnetic duality rotations of the source-free Maxwell action is anomalous in curved spacetimes. The classical Noether charge associated with these transformations accounts for the net circular polarization or the optical helicity of the electromagnetic field. Therefore, our results describe the way the spacetime curvature changes the helicity of photons and opens the possibility of extracting information from strong gravitational fields through the observation of the polarization of photons. We also argue that the physical consequences of this anomaly can be understood in terms of the asymmetric quantum creation of photons by the gravitational field.

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Particle Creation by Gravitational Fields

Physical Review Letters ◽

10.1103/physrevlett.36.999 ◽

1976 ◽

Vol 36 (17) ◽

pp. 999-1001 ◽

Cited By ~ 26

Author(s):

N. M. J. Woodhouse

Keyword(s):

Particle Creation ◽

Gravitational Fields

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Pharmacology Issues Related to Dementia Syndrome of Depression in Elderly Residents of Long-Term Care Settings

Perspectives on Neurophysiology and Neurogenic Speech and Language Disorders ◽

10.1044/nnsld25.2.61 ◽

2015 ◽

Vol 25 (2) ◽

pp. 61-69

Author(s):

Angel L. Ball ◽

Adina S. Gray

Keyword(s):

Depressive Symptoms ◽

The Elderly ◽

Environmental Communication ◽

Pharmacological Intervention ◽

Team Approach ◽

Discussion Paper ◽

Term Care ◽

Anticholinergic Medications ◽

Inappropriate Treatment ◽

Dementia Syndrome

Pharmacological intervention for depressive symptoms in institutionalized elderly is higher than the population average. Among the patients on such medications are those with a puzzling mix of symptoms, diagnosed as “dementia syndrome of depression,” formerly termed “pseudodementia”. Cognitive-communicative changes, potentially due to medications, complicate the diagnosis even further. This discussion paper reviews the history of the terminology of “pseudodementia,” and examines the pharmacology given as treatment for depressive symptoms in the elderly population that can affect cognition and communication. Clinicians can reduce the risk of misdiagnosis or inappropriate treatment by having an awareness of potential side effects, including decreased attention, memory, and reasoning capacities, particularly due to some anticholinergic medications. A team approach to care should include a cohesive effort directed at caution against over-medication, informed management of polypharmacology, enhancement of environmental/communication supports and quality of life, and recognizing the typical nature of some depressive signs in elderly institutionalized individuals.

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