De Hoop Research Articles

Where East Meets West: European Gas and Ukrainian Reality

On January 11, 2008, on the eve of the NATO summit meeting in Bucharest, the Ukrainian president, prime minister, and parliamentary speaker wrote to Secretary General Jaap de Hoop Scheffer, asking ...

Lp‐Lq time decay estimate to the solution of the Cauchy problem of the system of equations for nonlocal model of hyperbolic thermoelasticity theory

AbstractThe aim of this paper is to present a new system of equations describing nonlocal model of hyperbolic thermoelasticity theory. We used the Papkin and Gurtin approach based on the constitutive relations for internal energy e(x), and heat flux q(x), with integral terms. Such system of equations describes the propagation of thermal perturbation with finite velocity. Using the modified Cagniard–de Hoop's method we constructed the matrix of fundamental solutions for this system of equations in three–dimensional space. Basing on the constructed matrix of fundamental solutions in the explicit formula we represent the solution of the Cauchy problem to this system of equations in the form of some kind of convolutions. Next, applying the method of Sobolev spaces, we obtain the Lp−Lq time decay estimate to the solution of the Cauchy problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Significant population structure and asymmetric gene flow patterns amidst expanding populations of Clinus cottoides (Perciformes, Clinidae): application of molecular data to marine conservation planning in South Africa

Clinus cottoides is a fish endemic to the coast of South Africa, predominantly inhabiting rock pools. All South African clinids are viviparous, but probably breed throughout the year; as such, their dispersal may be limited, unlike species with pelagic larval stages. We analysed 343 fish from 14 localities on the west, south and east coasts using two mitochondrial genes and the second intron of the S7 ribosomal gene. Mitochondrial DNA analyses recovered significant genetic differentiation between fish populations from the east coast and other sampling locations, with a second break found between Gansbaai and Cape Agulhas on the south coast. Nuclear DNA recovered shallower, but significant, levels of population structure. Coalescent analyses suggested remarkably asymmetrical gene flow between sampling locations, suggesting that the cold Atlantic Benguela Current and Indian Ocean Agulhas counter-current play important roles in facilitating dispersal. There was no gene flow between the east coast and the other sites, suggesting that these populations are effectively isolated. Divergence times between them were estimated to at least 68 000 years. Neutrality tests and mismatch distributions suggest recent population expansions, with the exception of peripheral western and eastern populations (possibly a consequence of environmental extremes at the edge of the species distribution). Analyses of the current South African marine protected areas network show that it is not connected and that De Hoop, one of South Africa's largest marine reserves, appears to be an important source population of recruits to both the south and southwest coasts.

Learning for a Bright Future: Schooling, Armed Conflict, and Children’s Well‐Being

Learning for a Bright Future: Schooling, Armed Conflict, and Children’s Well‐Being

Helminth parasites of Natal long-fingered bats, <i>Miniopterus natalensis</i> (Chiroptera : Miniopteridae), in South Africa : research communication

The helminth community infecting Miniopterus natalensis was studied at two localities, the De Hoop Nature Reserve (DHNR) (n = 57), Western Cape Province and Pretoria (n = 12), Gauteng Province, South Africa. Hosts from the DHNR had formed part of an earlier, unrelated study and were all pregnant females. A single hymenolepidid cestode species, the nematodes Molinostrongylus ornatus and Litomosa chiropterorum together with nematodes of the subfamily Capillariinae were present at both study sites, while a single digenean, Allassogonoporus sp., was only found in hosts from the DHNR. The prevalence of helminth infections was high at both localities, 68.4% in the DHNR and 77.7% in Pretoria, whereas the mean intensity of infection was low at the DHNR (3.76 +/- 3.15), but higher in Pretoria (10.4 +/- 9.9). Molinostrongylus ornatus and, to a lesser extent L. chiropterorum, were the main contributors to the higher intensities in Pretoria. The species richness ranged from 0 to 4 at both localities.

Theories of case (review)

Reviewed by: Theories of case Helen de Hoop Theories of case. By Miriam Butt. (Cambridge textbooks in linguistics.) Cambridge: Cambridge University Press, 2006. Pp. xiii, 258. ISBN 9780521797313. $37.99. The first sentence of the introductory chapter states that the book is meant to serve as an introduction to various notions of case within modern theoretical linguistics. In fact, the book is much more than that. It not only provides an introduction to theories of case, but moreover puts together the various notions and insights coming from these theories in an illuminating way. The first chapter ('Introduction', 1–11) introduces the topic of the book: case. The important question addressed in this chapter is what the exact range of phenomena is that can be properly labeled 'case'. Notoriously, case is used to mark the semantic relationships between verbs and their arguments. But while some languages encode this relationship via morphological case, languages such as English encode it structurally, that is, in terms of designated positions. Thus, word order or structural position might be conceived of as an alternative strategy for marking the relationship between a verb and its arguments, and in that sense, it can be viewed as 'case' as well, which is of course a very common perspective in generative syntax. It is also clear, however, that word order and overt case marking are not truly alternative strategies for marking the relationship between a predicate and its argument since they are not complementary. Some languages have no case but yet a lot of word-order freedom, while other languages have both case and a strict word order. Similar problems as to what counts as 'case' are discussed with respect to head-marking versus dependent-marking languages, adverbial and nominal case, case stacking, and case and finiteness. Butt concludes that the notion of case employed in syntactic theories is an abstract notion used to characterize the interaction between verbal semantics, grammatical relations, and word order. The rest of the book is devoted to three guiding themes in order to allow for comparison across the theories: thematic roles, grammatical relations, and not surprisingly, overt case. Recurring topics throughout the other chapters are transitivity, unaccusativity, passivization, quirky case, and ergativity. Ch. 2 ('Foundational perspectives', 12–22) explains how modern theories of case developed from ancient traditions. B argues that due to the use of the Greek and Roman naming of cases, the fundamental assumption that case must be tied directly to semantics is still implicit in modern syntactic theorizing. This stands in stark contrast to the Indian tradition, where the case markers were simply numbered rather than associated directly with certain semantics. In the Arabic tradition, case is embedded within a larger theory of government in which the governor (a verb, preposition, or nominal) strictly determines the form of the governed element. This view led to a differentiation between two levels of representation at which government can take place, an underlying and a surface level of representation, reminiscent of certain versions of generative syntax. Ch. 3 ('Grammatical relations', 23–45) and Ch. 4 ('Structural case', 46–90) focus on the development of modern syntax (1950s onward). In early theories, such as transformational grammar and in particular relational grammar, grammatical relations were understood as abstract syntactic concepts that mediate between verbal semantics and case morphology. In Ch. 3 thematic roles in interaction with grammatical relations are introduced, while Ch. 4 explores the basic approach to case within the generative theories of government and binding and the minimalist program. In generative syntax, grammatical relations are associated with the assignment of structural (abstract) case. B argues that in contemporary generative syntax there is a trend toward incorporating ever more precise semantics into the structural representations. Ch. 5 ('Linking theories', 91–149) surveys a number of important linking theories, in particular Joan Bresnan's lexical functional grammar (LFG), Paul Kiparsky's linking theory, and Dieter Wunderlich's lexical decomposition grammar, theories of how predicate-argument structures are linked to syntactic structures. In these three approaches to argument linking, a number of features [End Page 620] play an important role. In LFG, the two relevant features are [+/restricted], which refers to the semantic restrictedness of a thematic...

Comments on: J. Rafa, C. Ziólkowski, “Influence of transmitter motion on received signal parameters – An analysis of the Doppler effect”, Wave Motion 45 (2008) 178–190

Comments are given on the basic equations of electrodynamics used for the analysis of the moving antenna problem under consideration and the use of the Cagniard–de Hoop method to arrive at the results.

Axisymmetric transient waves in transversely isotropic half-space

A transversely isotropic material in the sense of Green is considered. Using a series of potential functions proposed in [Eskandari-Ghadi M. A complete solution of the wave equations for transversely isotropic media. J Elasticity 2005; 81:1–19], the solutions of the transient wave equations within a half-space under surface load are obtained in the Laplace–Hankel domain for axisymmetric problems. The solutions are investigated in detail in the special case of a surface point force pulse varying with time as Heaviside function. Using Cagniard–De Hoop method, the inverse Laplace transform and inverse Hankel transform of the solutions are then obtained in the form of integrals with finite limits. For validity of the analytical results, the final formulations for surface waves are degenerated for an isotropic material and compared with the existing formulation obtained by Pekeris [The seismic surface pulse. Proc Natl Acad Sci USA 1955;41:469–80], to show that they are exactly the same. The numerical evaluations of the integrals for some transversely isotropic materials as well as an isotropic one are obtained. The present approach is then numerically verified by comparing a particular case of displacements for the surface of an isotropic half-space subjected to a point load of Heaviside function with the solutions obtained by Pekeris [The seismic surface pulse. Proc Natl Acad Sci USA 1955;41:469–80]. In addition, the wave equations for the mentioned medium are obtained on the vertical line directly under the applied surface load. The final formulations are degenerated for an isotropic material and compared with the existing formulation given in Graff [Wave motion in elastic solids. New York: Dover Publications Inc; 1975 [New Ed edition, November 1991]], to show that they are also exactly the same. Then equations are presented in graphical forms using an appropriate numerical evaluation.

Upper Mantle Heterogeneity beneath North America from Travel Time Tomography with Global and USArray Transportable Array Data

The large volume of broadband waveforms that are being acquired by USArray (http://www.iris.edu/USArray/), the seismology component of the national Earth science program EarthScope (http://www.earthscope.org/), offer unique opportunities for seismic imaging. Constraining structures on a range of length scales and understanding their physical and chemical causes is a prerequisite for understanding the relationship between near surface and deeper mantle processes. One can expect that, eventually, full wave tomography ( e.g. , De Hoop and van der Hilst 2005; De Hoop et al. 2006; Tromp et al. 2005; Zhao and Jordan 2006) with broadband USArray waveforms will produce superior insight into the structure of the mantle beneath North America, but linearized tomographic inversion of phase arrival time data readily yields exciting results in regions where data from dense seismograph networks is available. We will use travel times from the transportable component of USArray, hereinafter referred to as USArrayTA, and from other sources, such as the EHB data base (Engdahl et al. 1998), to constrain 3-D mantle heterogeneity beneath North America. Tomographic images based on USArrayTA data will help us understand first-order geological structure of and processes in the mantle beneath North America. Examples include, but are not restricted to: 1) the transition from the stable continental lithosphere at the center of the North American continent to the tectonically active domains farther west, 2) the Cascadian subduction system, 3) the Yellowstone hotspot, and 4) the relationship between current and past episodes of subduction and upper mantle upwellings and processes deeper in the mantle. Before the advent of USArrayTA, insight into mantle structure beneath the western United States was obtained either from pieced-together regional P -wave studies ( e.g. , figure 1A, after Dueker et al. 2001) or from global travel time or surface wave tomography (figures 1B, C, and D, …

To follow or not to follow: decision making and leadership during the morning departure in chacma baboons

To benefit from group living, group members need to keep the group cohesive by coordinating time and direction of travelling. Self-organization and leadership are two means of coordination and two types of decision can be made on the group level: combined and consensus. We studied the initiation process of group movements during the morning departure of a group of chacma baboons, Papio hamadryas ursinus, from its sleeping site in De Hoop Nature Reserve, South Africa. Findings from other female-bonded primate groups led us to hypothesize that females should play a major role in the decision-making process. Approximately 75% of the adults made a start attempt, with 62 of 92 attempts being by males. There was no sex difference in the probability of being successful when initiating an attempt. Lactating females initiated fewer than pregnant or cycling females. Thus, at least for this group of chacma baboons, leadership appeared to be distributed and the decision about the timing of departure and travel direction seemed to be a partially shared consensus decision with adult males contributing more to the decision outcome, with a slightly more prominent role of the dominant male. Our results do not support the ‘leading females’ hypothesis. No behavioural patterns that might serve as specialized signals leading to a more successful recruitment of other group members were observed. The departure process appeared to be coordinated merely through individuals setting an example by moving off.

The PfP Consortium “Community of Experts” Approach to International Security Cooperation

The Partnership for Peace (PfP) Consortium of Defense Academies and Security Studies Institutes epitomizes a fundamental truth: “Long-term security and stability requires more than the transformation of our military forces in terms of new hardware. It also requires a mental transformation.” This assessment of the Consortium was provided by NATO Secretary-General Jaap de Hoop Scheffer in his opening speech at its tenth anniversary celebration in Brussels on 18 June 2008, where he issued a call to reflect, take stock of what the Consortium had achieved, and look ahead. Citing it as a model for the future as NATO enlarges its concept of “Partnership,” the SecretaryGeneral situated the Consortium in the context of three phases of the Alliance’s own evolution. First was the Cold War, when NATO concentrated on territorial defense and had no formal relations with countries outside the Alliance. The end of the Cold War afforded the opportunity to build an undivided Europe and required an “open community” approach. In this second phase, the Partnership for Peace became NATO’s standard “for successful military cooperation between NATO and non-NATO countries, between big and small countries, and between countries with different geographical regions and with different security traditions.” De Hoop Scheffer added that, “PfP not only brought them together—it also brought out the best in them.” In support of these goals, the PfP Consortium developed a wide network of institutions and individuals, including both academics and practitioners. The Secretary-General cited its continuing relevance as it had become “the flagship of Defense Institution Building and plays a major role in security sector reform.” The events of 11 September 2001, however, ushered in the third phase of the Alliance’s evolution, forcing it to find answers to challenges that are truly global in nature. This phase, Mr. de Hoop Scheffer argues, “may be the most challenging,” but optimism was apparent in his Consortium address:

The Interpretation of Isaiah 56:1-9: Comfort or Criticism?

Research Article| December 01 2008 The Interpretation of Isaiah 56:1-9: Comfort or Criticism? Raymond de Hoop Raymond de Hoop Search for other works by this author on: This Site Google Journal of Biblical Literature (2008) 127 (4): 671–695. https://doi.org/10.2307/25610149 Cite Icon Cite Share Icon Share Facebook Twitter LinkedIn MailTo Permissions Search Site Citation Raymond de Hoop; The Interpretation of Isaiah 56:1-9: Comfort or Criticism?. Journal of Biblical Literature 1 January 2008; 127 (4): 671–695. doi: https://doi.org/10.2307/25610149 Download citation file: Zotero Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All Scholarly Publishing CollectiveSBL PressJournal of Biblical Literature Search Advanced Search The text of this article is only available as a PDF. Article PDF first page preview Close Modal You do not currently have access to this content.

Mathematical and physical aspect of the solution of the Cauchy problem for a system of equations describing a nonlocal model of propagation of heat with finite speed

AbstractIn our paper we present a new system of equations describing a nonlocal model of propagation of heat with finite speed in three‐dimensional space. Such a system of equations is described by a system of integral – differential equations. At first using the modiffied Cagniard de Hoop method, we construct the fundamental solution of this system of equations. On the basis of the constructed fundamental solution we obtain the explicite formulate of the solution of the Cauchy problem for this system of equations and applying the method of Sobolev and Biesov spaces, we get Lp – Lq time decay estimate for the solution of the Cauchy problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Monitoring and management of the endangered Cape mountain zebra Equus zebra zebra in the Western Cape, South Africa

AbstractDe Hoop Nature Reserve and a neighbouring conservancy contain the most genetically diverse subpopulation of the Endangered (IUCN) Cape mountain zebra (Equus zebra zebra Linnaeus 1758). Although vital for the long‐term stability of the meta‐population, the population had received limited monitoring post‐1999. We summarize data obtained during a population monitoring programme established in 2005. Ninety‐nine individuals were identified indicating a decline in annual population growth from 6.6% (1995–1999) to 4.5% (1999–2005). The population was male biased and the deficit of females is likely to have prevented additional breeding herd formation resulting in excess nonbreeding males. These animals are currently of limited reproductive value to the meta‐population and may be contributing to the decline in reproductive potential at De Hoop by competing for limited resources. One solution may be to translocate ‘excess’ males to reinforce existing small populations or establish new populations with females from elsewhere provided that a minimum of 78 animals is maintained at De Hoop to limit genetic loss. Population monitoring and effective management strategies for the De Hoop population and the meta‐population are vital to ensure the long‐term survival of Cape mountain zebra and for the success of other species recovery programmes.

Dynamic interfacial crack propagation in elastic–piezoelectric bi-materials subjected to uniformly distributed loading

In transversely isotropic elastic solids, there is no surface wave for anti-plane deformation. However, for certain orientations of piezoelectric materials, a surface wave propagating along the free surface (interface) will occur and is called the Bleustein–Gulyaev (Maerfeld–Tournois) wave. The existence of the surface wave strongly influences the crack propagation event. The nature of anti-plane dynamic fracture in piezoelectric materials is fundamentally different from that in purely elastic solids. Piezoelectric surface wave phenomena are clearly seen to be critical to the behavior of the moving crack. In this paper, the problem of dynamic interfacial crack propagation in elastic–piezoelectric bi-materials subjected to uniformly distributed dynamic anti-plane loadings on crack faces is studied. Four situations for different combination of shear wave velocity and the existence of MT surface wave are discussed to completely analyze this problem. The mixed boundary value problem is solved by transform methods together with the Wiener–Hopf and Cagniard–de Hoop techniques. The analytical results of the transient full-field solutions and the dynamic stress intensity factor for the interfacial crack propagation problem are obtained in explicit forms. The numerical results based on analytical solutions are evaluated and are discussed in detail.

Water procurement and the environment: A comparative history of South Africa’s Nandoni and De Hoop dams 1994-2007

Die konstruksie van damme in Suid-Afrika het in onlangse jare uiteenlopende response tot gevolg gehad in die geledere van die omgewingsbewuste lede van die land se burgerlike samelewing. Twee voorbeelde is die De Hoop- en Nandonidam wat onderskeidelik in Mpumalanga en die Limpopoprovinsie geleë is. Hierdie damme oefen albei ‘n bepalende invloed uit op die omgewing in die wêreldbekende Nasionale Krugerwildtuin (NKW). Albei is geleë in die opvanggebied van riviere wat deur die wildtuin vloei. Hierdie damme het ‘n belangrike rol om te speel. Benewens die feit dat hulle, in sommige gevalle, in van die land se mees agtergeblewe streke voorkom, het albei grootliks ten doel om ontwikkeling te stimuleer. Die Suid-Afrikaanse regering het tans ‘n beleidsdoelwit om armoede in die land teen 2015 uit te wis. Hierdie beleid word in samewerking met die sakesektor om die doelwitte wat gestel is by wyse van samewerking te verwesentlik. Omgewingsbewustes het egter die ontwikkeling in sommige kontekste veroordeel. In die artikel word aandag gegee aan ‘n manier waarop die burgerlike samelewing, die regering en die sakesektor saamgewerk het om te onderhandel vir die voorsiening van water in streke wat waterarm is. In die besonder word aandag gegee aan die geskiedenis, sedert 1994, van die beplanning, voorbereiding en uitvoer van damkonstruksieprojekte in die Limpopoprovinsie en Mpumalanga.

An agent-based model of group decision making in baboons

We present an agent-based model of the key activities of a troop of chacma baboons (Papio hamadryas ursinus) based on the data collected at De Hoop Nature Reserve in South Africa. We analyse the predictions of the model in terms of how well it is able to duplicate the observed activity patterns of the animals and the relationship between the parameters that control the agent's decision procedure and the model's predictions. At the current stage of model development, we are able to show that across a wide range of decision parameter values, the baboons are able to achieve their energetic and social time requirements. The simulation results also show that decisions concerning movement (group action selection) have the greatest influence on the outcomes. Those cases where the model's predictions fail to agree with the observed activity patterns have highlighted key elements that were missing from the field data, and that would need to be collected in subsequent fieldwork. Based on our experience, we believe group decision making is a fertile field for future research, and agent-based modelling offers considerable scope for understanding group action selection.

The pseudo-primary field due to a point-source in a finely layered medium

SUMMARY Using the theory of wave propagation in a finely layered medium which grew out of the work of O'Doherty and Anstey we calculate synthetic VSP traces and the slant stack of the transmitted waves. The present work may be regarded as an application of the method described by Burridge, White & Papanicolaou (1988), Burridge & Chang (1989), and De Hoop, Burridge & Chang (1990). The anisotropy (transverse isotropy) due to the fine layering is apparent in the pulse arrival times and the shear wave splitting. It can be shown that the arrival times agree with the effective medium theory of Schoenberg & Muir (1989). However, that effective medium theory does not predict the observed pulse broadening. Our results can be obtained by combining ray theoretic amplitudes in the average medium with a changing pulse shape evolving according to a certain integro-differential equation governed by the medium statistics.

Transient analysis of dynamic crack propagation in piezoelectric materials

In this paper, the transient analysis of semi‐infinite propagating cracks in piezoelectric materials subjected to dynamic anti‐plane concentrated body force is investigated. The crack surface is assumed to be covered with an infinitesimally thin, perfectly conducting electrode that is grounded. In analyzing this problem, it has characteristic lengths and a direct attempt towards solving this problem by transform and Wiener‐Hopf techniques (Noble, 1958) is not applicable. In order to solve this problem, a new fundamental solution for propagating cracks in piezoelectric materials is first established and the transient response of the propagating crack is obtained by superposition of the fundamental solution in the Laplace transform domain. The fundamental solution to be used is the responses of applying exponentially distributed traction in the Laplace transform domain on the propagating crack surface. Taking into account the quasi‐static approximation, exact analytical transient solutions for the dynamic stress intensity factor and the dynamic electric displacement intensity factor are obtained by using the Cagniard‐de Hoop method (Cagnard, 1939; de Hoop, 1960) of Laplace inversion and are expressed in explicit forms. Numerical calculations of dynamic intensity factors are evaluated and the results are discussed in detail. The transient solutions for stationary cracks have been shown to approach the corresponding static values after the shear wave of the piezoelectric material has passed the crack tip.

Analytical and numerical solution of the elastodynamic strip load problem

AbstractAnalytical and numerical solutions of the elastodynamic problem of an instantaneous strip load on a half space are presented and compared. The analytical solution is obtained using the De Hoop–Cagniard method, and the numerical solution is obtained using the dynamic module of the finite element package Plaxis. The purpose of the paper is to validate the numerical solution by comparison with a completely analytical solution, and to verify that the main characteristics of the analytical solution are also obtained in the numerical solution. Particular attention is paid to the magnitude, the velocity, and the shape of the Rayleigh wave disturbances. Copyright © 2007 John Wiley & Sons, Ltd.