Evaluating the Wald entropy from two-derivative terms in quadratic actions
- Brustein, R, Gorbonos, D, Hadad, M, Medved, A J M
- Authors: Brustein, R , Gorbonos, D , Hadad, M , Medved, A J M
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6816 , http://hdl.handle.net/10962/d1004326
- Description: We evaluate the Wald Noether charge entropy for a black hole in generalized theories of gravity. Expanding the Lagrangian to second order in gravitational perturbations, we show that contributions to the entropy density originate only from the coefficients of two-derivative terms. The same considerations are extended to include matter fields and to show that arbitrary powers of matter fields and their symmetrized covariant derivatives cannot contribute to the entropy density. We also explain how to use the linearized gravitational field equation rather than quadratic actions to obtain the same results. Several explicit examples are presented that allow us to clarify subtle points in the derivation and application of our method.
- Full Text:
- Date Issued: 2011
- Authors: Brustein, R , Gorbonos, D , Hadad, M , Medved, A J M
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6816 , http://hdl.handle.net/10962/d1004326
- Description: We evaluate the Wald Noether charge entropy for a black hole in generalized theories of gravity. Expanding the Lagrangian to second order in gravitational perturbations, we show that contributions to the entropy density originate only from the coefficients of two-derivative terms. The same considerations are extended to include matter fields and to show that arbitrary powers of matter fields and their symmetrized covariant derivatives cannot contribute to the entropy density. We also explain how to use the linearized gravitational field equation rather than quadratic actions to obtain the same results. Several explicit examples are presented that allow us to clarify subtle points in the derivation and application of our method.
- Full Text:
- Date Issued: 2011
Late Quaternary environmental phases in the Eastern Cape and adjacent Plettenberg Bay-Knysna region and Little Karoo, South Africa
- Authors: Lewis, Colin A
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6712 , http://hdl.handle.net/10962/d1006749
- Description: Four major climato-environmental phases have been identified in the Eastern Cape, Plettenberg Bay-Knysna region and Little Karoo between somewhat before ~ 40 000 cal. a BP and the present: the Birnam Interstadial from before 40 000 cal. a BP until ~ 24 000 cal. a BP; the Bottelnek Stadial (apparently equating with the Last Glacial Maximum) from ~24 000 cal. a BP until before ~ 18 350 cal. a BP; the Aliwal North (apparently equating with the Late Glacial) from before ~ 18 350 cal. a BP until ~ 11 000 cal. a BP; the Dinorben (apparently equating with the Holocene) from ~ 11 000 cal. a BP until the present. The evidence for, and the characteristics of, these phases is briefly described.
- Full Text:
- Date Issued: 2011
- Authors: Lewis, Colin A
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6712 , http://hdl.handle.net/10962/d1006749
- Description: Four major climato-environmental phases have been identified in the Eastern Cape, Plettenberg Bay-Knysna region and Little Karoo between somewhat before ~ 40 000 cal. a BP and the present: the Birnam Interstadial from before 40 000 cal. a BP until ~ 24 000 cal. a BP; the Bottelnek Stadial (apparently equating with the Last Glacial Maximum) from ~24 000 cal. a BP until before ~ 18 350 cal. a BP; the Aliwal North (apparently equating with the Late Glacial) from before ~ 18 350 cal. a BP until ~ 11 000 cal. a BP; the Dinorben (apparently equating with the Holocene) from ~ 11 000 cal. a BP until the present. The evidence for, and the characteristics of, these phases is briefly described.
- Full Text:
- Date Issued: 2011
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