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Ben-Dov, Jonathan

doi:10.1163/ej.9789004170889.ii-332

Cited by 54 publications

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“…(See, e.g., [8,9] for non-spherical trapped surfaces.) We use this here as an example to illustrate the relation between the regions where trapped surfaces occur and space-time singularities.…”

Section: Example: Schwarzschild Geometrymentioning

confidence: 99%

Singularities and Quantum Gravity

Bojowald¹

2007

AIP Conference Proceedings

108

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Abstract.Although there is general agreement that a removal of classical gravitational singularities is not only a crucial conceptual test of any approach to quantum gravity but also a prerequisite for any fundamental theory, the precise criteria for non-singular behavior are often unclear or controversial. Often, only special types of singularities such as the curvature singularities found in isotropic cosmological models are discussed and it is far from clear what this implies for the very general singularities that arise according to the singularity theorems of general relativity. In these lectures we present an overview of the current status of singularities in classical and quantum gravity, starting with a review and interpretation of the classical singularity theorems. This suggests possible routes for quantum gravity to evade the devastating conclusion of the theorems by different means, including modified dynamics or modified geometrical structures underlying quantum gravity. The latter is most clearly present in canonical quantizations which are discussed in more detail. Finally, the results are used to propose a general scheme of singularity removal, quantum hyperbolicity, to show cases where it is realized and to derive intuitive semiclassical pictures of cosmological bounces. OVERVIEWPhysical theories are always idealizations without which the complexity of nature would be too great to fathom. Theoretical physics is, mostly very successfully, based on assumptions needed to formulate equations, find solutions and use them to describe, explain and further investigate physical phenomena.Sometimes, however, these assumptions may not be general enough for all purposes. When they are violated, the theory breaks down which mathematically appears as the development of singularities. An example is given by the use of continuous fields rather than discrete atomic structures in condensed matter physics. When fields vary too strongly on small length scales, such as in shock waves, singularities can occur in continuous field equations even though the basic, discrete physical description remains valid. Usually, deviations between solutions and observations increase before a mathematical singularity is reached. It is then clear that the approximate description can no longer be trusted beyond a certain point. But observations are not always available in such regimes where singularities are approached and an interpretation of mathematical singularities becomes more difficult. This is the case especially for gravity where observations of strong field regimes are lacking.Singularities in general relativity therefore play a special and dual role. First, the classical importance of singularities can be questioned since there are always assumptions behind special solutions or general theorems leading to singularities. But classical singularities in general relativity also provide an excellent chance to derive implications for the structure of space-time described by general relativity. When the theory breaks down, lesson...

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Section: Example: Schwarzschild Geometrymentioning

confidence: 99%

Singularities and Quantum Gravity

Bojowald¹

2007

AIP Conference Proceedings

108

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“…Hospedeiro. Poaceae (Jakubski, 1965;ben-dov, 2005;Foldi, 2005 Foldi, 1987:156 (sinonimizado por Foldi, 1989.…”

Section: Termitococcus Carratoi Silvestri 1936 (Figs 3-5)unclassified

“…(ameixeira), Prunus avium (cerejeira), P. domestica (ameixeira preta), P. persica (pessegueiro), Pyrus communis (pereira), Rosa sp. (roseira); Rubiaceae: Gardenia jasminoides (gardênia); Salicaceae: Salix babylonica (salgueiro), S. humboldtiana (salseiro, chorão); Solanaceae: Solanum pseudoquina (quina branca), S. tuberosum (batatinha); Apiaceae: Apium graveolens (aipo), Daucus carota (cenoura), Petroselinum crispum (salsinha); Vitaceae: Vitis labrusca (videira americana), V. vinifera (videira européia); Zingiberaceae: Hedychium coronarium (lírio-do-brejo) (costa, 1937;lepaGe, 1938;costa, 1941, 1944liMa, 1947;vernalha, 1953;bertels, 1956;FaGundes et al, 1963;Jakubski, 1965;bertels & baucke, 1966;Mariconi & ZaMith, 1973;botton et al, 2000;ben-dov, 2005;Foldi, 2005).…”

Section: Termitococcus Carratoi Silvestri 1936 (Figs 3-5)unclassified

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Revisão taxonômica de Termitococcinae (Hemiptera, Coccoidea, Margarodidae)

Silva

Carvalho

2012

Iheringia, Sér. Zool.

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ABSTRACT. Taxonomic revision of the Termitococcinae (Hemiptera, Coccoidea, Margarodidae). The species of Termitococcinae are revised. This subfamily, restricted to the Neotropical region, is composed of five valid species included in two genera: Termitococcus aster Silvestri, 1901, Termitococcus carratoi Silvestri, 1936, Eurhizococcus brasiliensis (Wille, 1922, Eurhizococcus brevicornis (Silvestri, 1901), and Eurhizococcus colombianus Jakubski, 1965. The present study provides the redescription of these species, including the morphological characterization of the three stages (crawlers, cyst and adult female). Identification keys and illustrations for the species are also included. Lectotypes and paralectotypes of two species are designated. KEYWORDS.Taxonomy, scale insect, ground pearls, Neotropical. RESUMO.As espécies de Termitococcinae são revisadas. Esta subfamília, restrita à Região Neotropical, é composta de cinco espécies válidas, incluídas em dois gêneros: Termitococcus aster Silvestri, 1901, Termitococcus carratoi Silvestri, 1936, Eurhizococcus brasiliensis (Wille, 1922, Eurhizococcus brevicornis (Silvestri, 1901) e Eurhizococcus colombianus Jakubski, 1965. O estudo traz a redescrição das espécies da subfamília, incluindo a caracterização morfológica dos três estágios de desenvolvimento (ninfa ambulatória, cisto e fêmea adulta). Chaves de identificação e ilustrações são também incluídas. São designados lectótipos e paralectótipos para duas espécies.

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“…The general structure of Scale Insects, edition 2 emulates a number of Lucid-based tools for pest identification created and/or funded by the USDA Animal and Plant Health Inspection Service (APHIS), Identification Technology Program (ITP), and which can be found at http://idtools.org/id/. Our tool differs from all of them by being extensively linked to a comprehensive database on scale insects, ScaleNet (Ben-Dov et al 2012). ScaleNet is unusual in that it is not only a specimen database per se , but a complex model of the scale insect literature ( c. 25,000 references) (Hardy 2013).…”

Section: Introductionmentioning

confidence: 99%

Scale Insects, edition 2, a tool for the identification of potential pest scales at U.S.A. ports-of-entry (Hemiptera, Sternorrhyncha, Coccoidea)

Miller¹,

Rung²,

Parikh³

2014

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We provide a general overview of features and technical specifications of an online, interactive tool for the identification of scale insects of concern to the U.S.A. ports-of-entry. Full lists of terminal taxa included in the keys (of which there are four), a list of features used in them, and a discussion of the structure of the tool are provided. We also briefly discuss the advantages of interactive keys for the identification of potential scale insect pests. The interactive key is freely accessible on http://idtools.org/id/scales/index.php

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Head of All Years

Cited by 54 publications

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Singularities and Quantum Gravity

Singularities and Quantum Gravity

Revisão taxonômica de Termitococcinae (Hemiptera, Coccoidea, Margarodidae)

Scale Insects, edition 2, a tool for the identification of potential pest scales at U.S.A. ports-of-entry (Hemiptera, Sternorrhyncha, Coccoidea)

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