bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of translucent FDM parts by post‐processing
Authors: Ahn Sung‐Hoon , Lee Caroline S. , Jeong Woobyok
Published: August 2004

Rapid prototyping (RP) technologies provide the ability to fabricate initial prototypes from various model materials. Stratasys' fused deposition modeling (FDM) is a typical RP process that can fabricate prototypes out of ABS plastic. Translucent plastics are commonly used in packaging for mechanical and electrical components. Although various materials are used in RP, translucent RP parts are not readily available from most RP processes. In this paper, two post‐processing techniques were applied in order to increase the optical transmissivity of the parts made of ABSi. First, elevated temperature was applied resulting in increased transmissivity while dimensional shrinkage was observed. Second, resin infiltration and surface sanding provided up to 16 percent transmissivity without shrinkage. These post‐processes can be selectively applied to increase the transmissivity of ABSi parts. Thus, translucent FDM parts can be fabricated from the regular FDM process followed by the post‐processes developed in this study.
RP of Si3N4 burner arrays via assembly mould SDM
Authors: Liu Hao‐Chih , Lee Sunyoup , Kang Sangkyun , Edwards Christopher F. , Prinz Fritz B.
Published: August 2004

A rapid prototyping process applying ceramic gelcasting and assembly mould shape deposition manufacturing has been developed to fabricate mesoscale silicon nitride components with complex 3D geometry. An overview of the fabrication of Si3N4 burner arrays for gas turbine reheat applications is demonstrated. The design of burner arrays features internal fuel passages and integrated fuel injection elements, which cannot be manufactured by conventional methods. Geometrical decomposition of design models and recent developments in ceramic processing provide a novel approach in prototyping the burner arrays. In this paper, issues of materials compatibility, mould fabrication strategies, ceramic processing, and design iterations will be discussed along with the functional test of the 4×4 burner array.
Stereolithography assisted redesign and optimisation of a dishwasher spraying arm
Authors: Dedoussis V. , Giannatsis J.
Published: August 2004

The aim of this paper is to show how models fabricated via stereolithography (SL) served as “functional prototypes” for the redesign and optimisation of the spraying arm of a small dishwashing machine. The redesign process depended entirely on systematic experimental testing. SL modelling was employed in order to realise the various geometries proposed for the “new” spraying arm. The SL built spraying arm models (prototypes) themselves were used in the actual experiments, i.e. during the various dishwashing cycles. Their behaviour was very satisfactory. The methodology followed is presented in a systematic way. Aspects such as the effect of various build parameters on the models' functionality as well as “engineering solutions” given to problems encountered during fabrication and testing of the models are discussed in detail.
Compression testing of layer manufactured metal parts: the RAPTIA compression benchmark
Authors: Dalgarno K.W. , Goodridge R.D.
Published: August 2004

This paper reports the results of a compression test benchmarking study carried out to investigate the mechanical properties of layer manufactured metal components in order to assess their suitability in load bearing applications. Compression tests were carried out on the DTM LaserForm ST‐100 material, ARCAM processed H13 tool steel, EOS DirectSteel (50 μm), and the ProMetal material. It is concluded that the LaserForm ST‐100 material, the ARCAM H13 tool steel material, and the ProMetal material all exhibit responses to compressive loads which make them suitable for use in load bearing situations, whilst the EOS DirectSteel (50 μm) exhibits a small permanent set in compression, making it less suitable in these situations.
Knowledge architectures for cultural narratives
Authors: Srinivasan Ramesh
Published: August 2004

This paper introduces a new approach toward applying ideas of knowledge management toward the domain of culture and communities. A set of precedents are discussed, all of which have focused on the design of digital media systems for communities. Two knowledge management techniques, previously not discussed within prevailing literature, are introduced within specific projects. The application of these techniques, anticipated and received results, and general implications of this research on the field of knowledge management are highlighted. This paper finds that approaching new cultural and community‐focused domains yields new, satisfying techniques toward the management of knowledge. The techniques of community‐driven ontology and proactive agents are discussed and evaluated as design approaches toward the problem of creating meaningful knowledge architectures for community‐focused media systems. Knowledge management, as a paradigm, can apply to a number of domains that are not solely business‐focused. The re‐application of these principles can generate meaningful approaches toward how the knowledge architectures that mediate digital media systems for communities and cultures. Discussion of two new approaches toward knowledge management and knowledge architectures. This research is a focus on of these techniques in the new, critical environment of communities, culture, and narratives. This paper allows researchers and students of knowledge management to begin to approach the ideas of mediating knowledge more broadly. It engages the language and approach of design into the field of knowledge management. Finally, it creates an opportunity to begin to apply more heterogeneous research to the burgeoning field of knowledge management.
From sashimi to zen‐in: the evolution of concurrent engineering at Fuji Xerox
Authors: Umemoto Katsuhiro , Endo Atsushi , Machado Marcelo
Published: August 2004

This case study examines the evolution of R&D knowledge management at Japan’s business equipment maker Fuji Xerox, from the sashimi system, a Japanese origin of concurrent engineering, to its successor zen‐in system, which is composed mainly of a real high‐tech discussion room equipped with databases that provide technical information and two 70‐inch displays that shows virtual but real‐size, three‐dimensional graphic models. We found that Fuji Xerox has chosen the “hybridization strategy” that mixes human‐based and IT‐based knowledge‐sharing techniques. We also argue that concurrent engineering provides not only efficiency benefits but also positive effects on group and organizational creativity. Finally we present a conceptual framework of “how concurrent engineering works”, i.e. uncertainty and diversity necessitate concurrency which produces such benefits as efficiency and creativity, and which in turn realizes product integrity.
Technology challenges for the global real‐time enterprise
Authors: Vogels Werner
Published: August 2004

This paper reviews the real‐time enterprise from a technology point of view, with a strong focus on the challenges of building globally scalable technology. We analyze the different aspects of the real‐time enterprise and the link between the real‐time functionality and event driven systems. We then review the major bottlenecks in achieving scalability and robustness for event‐driven systems when they need to support global enterprise systems. At a conceptual level the real‐time enterprise is extremely promising but neither research nor product groups have the technologies to operate at a global scale in a manner that will allow the real‐time enterprise to become a reality, unless a number of significant hurdles are removed. This paper examines the impact of the concept of the real‐time enterprise on research agenda of academia as well as product groups, and lays out an agenda for achieving scalability and reliability goals.
Group cognition as a basis for supporting group knowledge creation and sharing
Authors: Nosek John T.
Published: August 2004

This paper explores how group cognition can provide a basis for understanding knowledge creation and sharing that does not depend on the assumption of extant internal representations that filter sense‐data. Literature from a wide variety of disciplines is synthesized to provide an ecologically‐oriented model of group cognition. Group cognition means moving away from idiosyncratic, subjective mental models of the world to the notion that agents with similar capacities to act can potentially discern similar action possibilities in the world. It changes the direction from discovery and alignment of mental models to selectivity calibration and informational structure sharing. “What one thinks” at a given moment is dependent on boundary objects available at the moment that predominately originate with human actors. Therefore, in this way, one’s cognition is predominately group cognition. Based on the breadth of the topic, this paper must be considered a work‐in‐progress, a snapshot of the exploration of such a complex subject. It provides an alternate view of knowledge creation and sharing as the basis for incorporating more effective collaboration functionality into technologies that support joint work. This paper challenges long‐held views of extant internal representations that filter sense‐data and offers a radically different ecological‐based model of group cognition.
Theology is not Mere Sociology: A Theological Reflection on the Reception of the Christian Religion in Mainland China
Authors: LO Pilgrim W.K.
Published: August 2004

Abstract:  Post‐Maoist China retains its loyalty to Marxist principles; yet voices are being heard that interpret religion much more positively. Both government spokespersons and Religious Studies scholars measure the value of religion according to its social function. Such a criterion of evaluation fails to take account of what is essential to Christian theology, namely, appeal to divine transcendence. Yet, Christian theology in the tradition of the Lutheran Reformation begins with transcendence and turns toward human responsibility for the world through loving the neighbor. This may mark a common cause between Chinese sociology of religion and Christian commitments to social well‐being.
Gay/Lesbian Ordination and the Ontology of the Human Subject
Authors: Elise Lowe Mary
Published: August 2004

Abstract:  Should gay and lesbian persons be ordained? Many anthropological issues are involved in this question: human sexuality, the image of God, and the doctrine of sin. I contend that one of the central—yet unexplored—issues in this debate is the view of the human subject. This article summarizes the non‐ontological anthropologies developed by Wolfhart Pannenberg, Rosemary Ruether, and Mary McClintock Fulkerson. All suggest that subjects are constitutionally related to the world and avoid predicating attributes, such as gender or rationality to supposedly autonomous subjects. These non‐ontological models offer new ways to view the subject, gender, and the debate concerning ordination.
Reclaiming Bonhoeffer After Auschwitz
Authors: Smith Robert O.
Published: August 2004

Abstract:  Christians having sought refuge from guilt by claiming Nazi martyr Dietrich Bonheoffer to be their representative have come under critique by Jewish Holocaust thinkers. Was the historical Bonhoeffer complicit in the anti‐Semitism of his era or a model of prophetic heroism in the face of state sponsored racism and genocide? This article traces the early history of Bonhoeffer's thinking on the “Jewish Question” and the implications of his prison writings for the future of Jewish‐Christian relations. Simplistic defenses and simplistic dismissals fall short of understanding this most complex of theological figures.
Discarding the Barthian Spectacles: Part I, Recent Scholarship on the History of Early 20th Century German Protestant Theology
Authors: Aune Michael B.
Published: August 2004

Abstract:  This essay introduces “the veritable renaissance” of scholarly attention devoted to the theologies of the early twentieth century. This “renaissance” challenges us to discard the “Barthian spectacles” through which we have been reading the theological history of this time and to examine more closely the complex context—social, political, churchly, cultural—in which theology was done.
The Christian Faith in an Inter‐Faith Context
Authors: Braaten Carl E.
Published: August 2004

Abstract:  In developing a Christian Theology of the World Religions, this article makes the following claims: (1) the central issue is Christology including the all‐sufficiency of Christ's work to accomplish salvation for all; (2) by distinguishing between general and special revelation, Christians can confirm that God has witnesses among all the world's religions; (3) Christianity ought to continue to live out of its missionary impulse, to proclaim the gospel of salvation, and to provide an apologetic defense of its truth claims; (4) Christian clergy should approach inter‐faith settings with extensive knowledge of the world's religions; (5) and seminaries should revamp their curricula to teach a truly Christian theology of World Religions.
Toward a Christian‐Islamic Ecumenic Encounter
Authors: Wagner Walter
Published: August 2004

Abstract:  Ted Peters’ framework for ecumenic engagement provides elements that will advance such an encounter with Islam. Applying several of Peters’ terms to interreligious relationships, Walter Wagner looks at various meetings between Muhammad and Christians contemporary to him. He cites the contacts between Muhammad and the first Muslim communities with Christians (610–632 AD) as both negative and positive paradigms for subsequent relationships. Wagner then points to Surah 1 as the key Quranic text for understanding Islam in relationship to Christianity. Reflecting on past efforts at dialogue and predicting what will be important future issues, Wagner stresses the intense religious nature of Islamic political‐social expectations and projects three factors for future ecumenic encounters between Islam and Christianity.
Reconstituting Paradise Lost: Temporality, Civility, and Ethnicity in Post-Communist Constitution-Making
Authors: Přibáň Jiří
Published: August 2004

This article focuses on constitutional developments and legal policies in Central Europe since 1989 and elaborates on their temporal analysis with special emphasis on the distinction between demos and ethnos in the political and legal discourse. Using various social theories of time, identity, and codification of social traditions, I argue that the difference between civility and ethnicity does not involve simply a conflict between liberal democratic aspirations and ethno-nationalist myths of authoritarian politics, but rather represents two distinct traditions manipulated by political agents and codified in the process of recent constitution-making. The process of selecting different traditions and political manipulations of the past is reflected at the level of both constitutional symbolism and specific governmental policies in post-Communist Hungary, Slovakia, Poland, and the Czech Republic. The final part of the text analyzes relations between the abstract symbolic language of constitutional documents and concrete, “ethnos-” based legal policies implemented in these countries of Central Europe.
Progress, Unity, and Democracy: Dissolving Political Parties in Turkey
Authors: Kogacioglu Dicle
Published: August 2004

In this article, I analyze two cases where the Turkish Constitutional Court dissolved political parties during the 1990s. Specifically, I examine the cases against the Islamist Refah (Welfare/Well-Being) Party and the pro-Kurdish Halkin Emek Partisi (People's Labor Party). While the former was charged with threatening the secular basis of the national social order, the charges against the latter were around its allegedly separatist character. I engage in an in-depth analysis of the lines of argument in the indictments, arguments of defense deployed by the parties, and their ultimate contestations as they appeared in the final decisions by the Court. I see the Court as engaging with a medley of themes and tendencies, [trying to resolve them for the case at hand]. I argue that despite the differences in the construction of the alleged threats, in both cases the Court deployed a similar image of the ways in which social, political, and judicial terrains interact. A rather arbitrary boundary between the political and cultural domains informs these decisions. The Court operates with the understanding that once this boundary is transgressed, what may be harmless when an issue is cultural—such as the use of the headscarf or of the Kurdish language—may turn into a political symbol threatening the basis of the united, democratic, and progressive nation-state. In this vision, the concepts of democracy, progress, and unity are intimately tied together such that the threat to one of these concepts almost simultaneously constitutes a threat to the other two. The Court imagines itself as protecting the boundary between the political and cultural domains in an effort to uphold the right of a democracy to protect itself. This line of thought also enables the court's rather routine involvement in the political domain—which has brought about eighteen decisions for political party dissolution since 1980.
“Constrained” Constitutional Courts as Conduits for Democratic Consolidation
Authors: Maveety Nancy , Grosskopf Anke
Published: August 2004

Many constitutional courts, particularly in Central and Eastern Europe, have more power than the “constrained court” model of judicial decisionmaking suggests because they operate in an increasingly international environment. By analyzing the Estonian Supreme Court's adjudication of minority linguistic rights, we show how even a new court can act as a “conduit” for democratic reform by identifying for legislators national constitutional paths along which domestically disliked but internationally defined democratic reforms can be pursued, preserving national integrity while acknowledging international reality. International pressures, while constraining courts, thus can free them from national constraints while allowing them to imprint their own vision.
Less Democracy, More Courts: A Puzzle of Judicial Review in Russia
Authors: Trochev Alexei
Published: August 2004

This article explores why, throughout the 1990s, some Russian regions created their own constitutional courts and others did not. Contrary to current theories that assert that politicians create a strong and independent judiciary to protect them from the tyranny of election-winners in the context of political uncertainty, my analysis finds that constitutional courts emerged only in those regions where governors virtually guaranteed their re-election by consolidating their political power vis-à-vis federal and local governments. The article argues that both federal and regional politicians used the process of creating subnational constitutional courts to legitimize their federalism and judicial reforms. The changes in the balance of power between those governors, who aspired to have their own judicial system, and the federal government that insisted on a single federal judicial system, determined the variation in the process of court-building across Russian regions.
Judicial Power in Russia: Through the Prism of Administrative Justice
Authors: Solomon Peter H.
Published: August 2004

This article assesses the power of judges in Russia (on courts of general jurisdiction,arbitrazhcourts, and military courts) in dealing with cases in which the government or one of its officials is a party. Power, that is, the resources of judges to make binding decisions, is understood as including jurisdiction, discretion, and authority to ensure compliance. The article analyzes the dramatic growth of jurisdiction and caseload in administrative justice in post-Soviet Russia to the year 2002 and examines how the courts have performed in handling the review of actions by officials (including in the military), tax cases, electoral disputes, and the legality of normative acts (both regulations and laws of lower governments), especially in the late 1990s. High rates of success for persons bringing suits against the government suggest that judges were able by and large to adjudicate fairly and rule against the state. To a considerable degree (but not always), those decisions were implemented (more often than were constitutional and commercial decisions). Interestingly, citizens who challenged the actions of officials in court had much more success than those who brought complaints to the Procuracy. Finally, the article develops an agenda for future research that would deepen understanding of the significance of administrative justice in the Russian Federation and the power of judges.
The Impact of Legal Mobilization and Judicial Decisions: The Case of Official Minority-Language Education Policy in Canada for Francophones Outside Quebec
Authors: Riddell Troy Q.
Published: August 2004

The article investigates the impact of legal mobilization and judicial decisions on official minority-language education (OMLE) policy in the Canadian provinces outside Quebec, using the “factor-oriented” and “dispute-centered” theories of judicial impact developed by U.S. scholars. The Canadian Supreme Court's decision in Mahé v. Alberta (1990), which broadly interpreted Section 23 of the Charter of Rights to include management and control of OMLE programs and schools, along with federal funding to the provinces to implement OMLE policy, are important to explaining OMLE policy change as predicted by the factor-oriented approach. The dispute-centered approach, on the other hand, helps us understand how the Charter of Rights and judicial decisions shaped the goals and discourse of Francophone groups in the policy process and, more instrumentally, provided opportunity structures that Francophone groups exploited effectively. The article concludes that both approaches to explaining judicial impact could be accommodated within an institutional model of judicial impact that construes institutions as state actors, as sets of rules, and as frameworks of meaning and interpretation. Such an approach would allow for the development of a more comparative model of judicial impact.
Photogrammetric Reconstruction of the Great Buddha of Bamiyan, Afghanistan
Authors: Grün Armin , Remondino Fabio , Zhang Li
Published: August 2004

In the valley of Bamiyan, Afghanistan, approximately 1700 years ago, two large standing Buddha statues were carved out of the sedimentary rock of the region. They were 53 and 38 m high and the larger one figured as the tallest representation of a standing Buddha in the world. In March 2001 the Taleban government militia demolished the colossal statues. After the destruction a group from ETH Zürich completed the computer reconstruction of the Great Buddha, which can serve as the basis for a physical reconstruction. This paper reports the results of the image‐based 3D reconstruction of the statue, performed on three different data‐sets in parallel and using different photogrammetric techniques and algorithms.
CREDIBILITY, MACROECONOMIC FUNDAMENTALS AND MARKOV REGIME SWITCHES IN THE EMS
Authors: Sarantis Nicholas , Piard Sylviane
Published: August 2004

The main objective of this paper is to use the Markov regime‐switching modelling framework to describe and analyse the credibility of a number of countries participating in the European Monetary System during 1980–1998. Our credibility indicator, based on Hughes Hallet et al.'s (1997) methodology, is subject to discrete regime shifts and is made dependent on macroeconomic fundamentals. We carry out extensive testing to assess the specification of the Markov regime‐switching model and the potential existence of permanent breaks. A contribution of our paper is the specification of a multivariate Markov switching model that allows us to examine whether macroeconomic variables have asymmetric effects on credibility. Another contribution is the specification of a regime‐switching model with time‐varying transition probabilities, which enables us to determine whether changes in macroeconomic variables can trigger switches between the low and high credibility regimes. We find strong evidence of regime switching behaviour in all countries. Both the level of credibility and the transition probabilities display an asymmetric response to changes in macroeconomic variables, with the stance of fiscal policy exerting the most systematic influence in all countries.
IS THE VIEW FROM THE EUROTOWER PURELY EUROPEAN? – NATIONAL DIVERGENCE AND ECB INTEREST RATE POLICY
Authors: Heinemann Friedrich , Huefner Felix P.
Published: August 2004

The official view on ECB monetary policy claims that decisions are based on euro zone data and that diverging regional developments are disregarded. To test empirically whether regional developments have an impact on ECB decisions we develop a generalised monetary policy reaction function which allows for an influence of regional divergence. Reaction function estimations and a probit model of interest rate decisions for the first years of the euro area offer some first support for an impact of regional divergence. The results clarify that ignoring a potential national perspective may lead to biased estimates for the ECB reaction function.
Cation binding by acid‐washed peat, interpreted with Humic Ion‐Binding Model VI‐FD
Authors: Smith E. J. , Rey‐Castro C. , Longworth H. , Lofts S. , Lawlor A. J. , Tipping E.
Published: August 2004

A sample of ombrotrophic peat from Moor House in northern England was extensively extracted with dilute nitric acid (pH 1) to free it of bound cations. Suspensions of the acid‐washed peat (5–30 g l−1), prepared with different concentrations of background electrolyte (NaCl and KCl), were used to conduct batch acid–base titrations. A strong dependence of proton release on ionic strength (I) was observed, the apparent acid dissociation constant (pKapp) being found to decrease by approximately 1.0 for each tenfold increase in I. This behaviour could not be explained satisfactorily with Humic Ion‐Binding Model VI, a discrete‐site/electrostatic model of cation binding by humic substances, parameterized with data from laboratory studies on isolated samples. More success was obtained by abandoning the impermeable‐sphere electrostatic submodel used in Model VI, and instead assuming the peat to consist of aggregates with fixed internal volume, and with counterion accumulation described by the Donnan model, as proposed by Marinsky and colleagues. The fixed‐volume Donnan model (Model VI‐FD) could also approximately explain other reported results from acid–base titrations of peat, including the effects on the titrations of complexing cations (Al, Ca, Cu). Copper titrations of the Moor House sample were performed using an ion‐selective electrode, with peat suspensions in the acid pH range, at two ionic strengths, and in the presence of Al and Ca. The measured concentrations of Cu2+ were in the range 10−13−10−5 m. Model VI‐FD provided reasonable fits of the experimental data, after optimization of the intrinsic binding constant for Cu, the optimized value being close to the default value derived previously from data referring to isolated humic substances. The optimized constants for Al and Ca, derived from their competition effects, were also close to their default values. Additional experiments were performed in which the centrifugation‐depletion method was used to measure the binding of a cocktail of metals (Al, Ni, Cu, Zn, Cd, Eu, Pb) at a single pH. The model correctly predicted strong binding of Al, Cu, Eu and Pb, and weaker binding of Ni, Zn and Cd. For the strongly binding metals, the dissolved forms were calculated to be mainly due to complexes with dissolved humic matter, whereas the free ions (Ni2+, Zn2+, Cd2+) dominated for the weakly binding metals. Acid‐washed soil appears to provide a valuable intermediate between isolated humic substances and untreated soil for the investigation of cation binding by natural organic matter in the natural environment.
Anticlastogenic, antitoxic and sorption effects of humic substances on the mutagen maleic hydrazide tested in leguminous plants
Authors: Ferrara G. , Loffredo E. , Senesi N.
Published: August 2004

The potential anticlastogenic and antitoxic effects of a soil humic acid (HA), a peat HA and a peat fulvic acid (FA) on the mutagen maleic hydrazide (MH) have been investigated in two legume species, Vicia faba and Pisum sativum. Both HAs and FA were tested at two different concentrations, 20 and 200 mg l−1, either alone or after 24‐hour interaction with 10 mg l−1 of MH before addition to the legume seeds. Anticlastogenicity, i.e. an antimutagenic action defined as the capacity for minimizing chromosome breakages, was evaluated by counting both micronuclei (MN) and aberrant anatelophases (AAT) in root‐tip cells. Length and dry weight of the seedling primary root were measured to test the antitoxic activity of HA and FA on MH. The possible occurrence and extent of adsorption or desorption of MH onto or from HA were also investigated. The two species responded differently to the anticlastogenic tests, with V. faba showing a greater number of MN and AAT anomalies than P. sativum. Peat HA and FA exhibited anticlastogenic and antitoxic activities of similar intensity and greater than those of soil HA. The adsorption capacity of both HAs for MH was small, thus suggesting that adsorption is not a major mechanism responsible for the reduction of clastogenicity and antitoxicity of MH by HA.
Soil physical properties affected by long‐term fertilization
Authors: Pernes‐Debuyser A. , Tessier D.
Published: August 2004

According to the literature, soil physical properties are linked mainly with organic constituents that are often considered as the first indicator of soil fertility. But the use of fertilizers and amendments can change soil properties independently of the organic matter content. In a long‐term experiment at Versailles, fertilizers and amendments have been applied each year to uncultivated plots. After 70 years, the plots had the same low organic matter content except those which were treated with manure. However, the physico‐chemical environment had become strongly differentiated. Physical properties, especially soil water relations, were also greatly affected. The use of ammoniacal fertilizers strongly decreased soil pH and cation exchange capacity (CECsoil). Plots treated in this way were more sensitive to the degradation of their hydraulic properties and became unstable in spite of the preservation of their porosity. Basic amendments (i.e. bases added as CO32–, OH–, O2– or silicate anions) increased soil pH, CECsoil and its saturation by exchangeable calcium. The increase in CECsoil improved soil structural cohesion and water flow properties. After basic treatment, there is greater structural stability, and water moves faster through the soil. In potassic and sodic plots, K+ and Na+ affected water movement and increased the soil's sensitivity to degradation. Manure treatment increased water retention and soil stability. The cation exchange capacity, measured at soil pH, can be used as a good indicator of soil stability, in combination with the organic matter content and the kinds of exchangeable cation (especially K+ and Na+).
Soil invertebrate activity in biological crusts on tropical inselbergs
Authors: VaÇulik A. , Kounda‐Kiki C. , Sarthou C. , Ponge J. F.
Published: August 2004

Granite inselbergs protrude from forest and savanna in the tropics. They are exposed to harsh climates (alternation of heavy rain and severe drought) and provide little nutrient for plants. Soil animals and humus components were investigated in cyanobacterial crusts close to patches of epilithic vegetation on the surface of the Nouragues inselberg (French Guiana). Three biological crust samples, corresponding to bromeliacean carpets of increasing size (supposed of increasing age), were sampled for faunal and micromorphological studies. Arthropods (mainly mites and insects) were abundant and highly diversified, the more so after enchytraeid worms ate and transformed the cyanobacterial mass. Below the superficial cyanobacterial crust, humus was made of a loose assemblage of enchytraeid faeces where these animals were present, or of a compact assemblage of cyanobacteria and amorphous organic matter where mites were the dominant animal group. Roots abounded in the humified part of the crust. We conclude that soil invertebrates, in particular enchytraeid worms, are important for the accumulation of organic matter on granite outcrops, and so therefore for the encroachment of plant succession.
Podzolization as a deferralitization process: a study of an Acrisol–Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin
Authors: Do Nascimento N.R. , Bueno G.T. , Fritsch E. , Herbillon A.J. , Allard Th. , Melfi A.J. , Astolfo R. , Boucher H. , Li Y.
Published: August 2004

Morphological, geochemical and mineralogical studies were carried out in a representative soil catena of the low‐elevation plateaux of the upper Amazon Basin to interpret the steps and mechanisms involved in the podzolization of low‐activity clay soils. The soils are derived from Palaeozoic sandstones. They consist of Hydromorphic Podzols under tree savannah in the depressions of the plateaux and predominantly of Acrisols covered by evergreen forest elsewhere.

Incipient podzolization in the uppermost Acrisols is related to the formation of organic‐rich A and Bhs horizons slightly depleted in fine‐size particles by both mechanical particle transfer and weathering. Weathering of secondary minerals by organic acids and formation of organo‐metallic complexes act simultaneously over short distances. Their vertical transfer is limited. Selective dissolution of aluminous goethite, then gibbsite and finally kaolinite favour the preferential cheluviation of first Fe and secondly Al. The relatively small amount of organo‐metallic complexes produced is related to the quartzitic parent materials, and the predominance of Al over Fe in the spodic horizons is due to the importance of gibbsite in these low‐activity clay soils.

Morphologically well‐expressed podzols occur in strongly iron‐depleted topsoils of the depression. Mechanical transfer and weathering of gibbsite and kaolinite by organic acids is enhanced and leads to residual accumulation of sands. Organo‐metallic complexes are translocated in strongly permeable sandy horizons and impregnate at depth the macro‐voids of embedded soil and saprolite materials to form the spodic Bs and 2BCs horizons. Mechanical transfer of black particulate organic compounds devoid of metals has occurred later within the sandy horizons of the podzols. Their vertical transfer has formed well‐differentiated A and Bh horizons. Their lateral removal by groundwater favours the development of an albic E horizon. In an open and waterlogged environment, the general trend is therefore towards the removal of all the metals that have initially accumulated as a response to the ferralitization process and have temporarily been sequestrated in organic complexes in previous stages of soil podzolization.
A new model for the soil‐water retention curve that solves the problem of residual water contents
Authors: Groenevelt P. H. , Grant C. D.
Published: August 2004

We present a new model for the soil‐water retention curve, θ(hm), which, in contrast to earlier models, anchors the curve at zero water content and does away with the unspecified residual water content. The proposed equation covers the complete retention curve, with the pressure head, hm, stretching over approximately seven orders of magnitude. We review the concept of pF from its origin in the papers of Schofield and discuss what Schofield meant by the ‘free energy, F ’. We deal with (historical) criticisms regarding the use of the log scale of the pressure head, which, unfortunately, led to the apparent demise of the pF. We espouse the advantages of using the log scale in a model for which the pF is the independent variable, and we present a method to deal with the problem of the saturated water content on the semi‐log graph being located at a pF of minus infinity. Where a smaller range of the water retention is being considered, the model also gives an excellent fit on a linear scale using the pressure head, hm, itself as the independent variable. We applied the model to pF curves found in the literature for a great variety of soil textures ranging from dune‐sand to river‐basin clay. We found the equation for the model to be capable of fitting the pF curves with remarkable success over the complete range from saturation to oven dryness. However, because interest generally lies in the plant‐available water range (i.e. saturation, θs, to wilting point, θwp), the following relation, which can be plotted on a linear scale, is sufficient for most purposes: , where k0, k1 and n are adjustable fitting parameters.
Scale‐ and location‐dependent correlation of nitrous oxide emissions with soil properties: an analysis using wavelets
Authors: Lark R. M. , Milne A. E. , Addiscott T. M. , Goulding K. W. T. , Webster C. P. , O'Flaherty S.
Published: August 2004

This paper shows how the wavelet transform can be used to analyse the complex spatial covariation of the rate of nitrous oxide (N2O) emissions from the soil with soil properties that are expected to control the evolution of N2O. We use data on N2O emission rates from soil cores collected at 4‐m intervals on a 1024‐m transect across arable land at Silsoe in England. Various soil properties, particularly those expected to influence N2O production in the soil, were also determined on these cores.

We used the adapted maximal overlap discrete wavelet transform (AMODWT) coefficients for the N2O emissions and soil variables to compute their wavelet covariances and correlations. These showed that, over the transect as a whole, some soil properties were significantly correlated with N2O emissions at fine spatial scales (soil carbon content), others at intermediate scales (soil water content) and others at coarse spatial scales (soil pH). Ammonium did not appear to be correlated with N2O emissions at any scale, suggesting that nitrification was not a significant source of N2O from these soils in the conditions that pertained at sampling.

We used a procedure to detect changes in the wavelet correlations at several spatial scales. This showed that certain soil properties were correlated with N2O emissions only under certain conditions of topography or parent material. This is not unexpected given that N2O is generated by biological processes in the soil, so the rate of emission may be subject to one limiting factor in one environment and a different factor elsewhere. Such changes in the relationship between variables from one part of the landscape to another is not consistent with the geostatistical assumption that our data are realizations of coregionalized random variables.
The concentrations of fatty acids in organo‐mineral particle‐size fractions of a Chernozem
Authors: Jandl G. , Leinweber P. , Schulten H.‐R. , Eusterhues K.
Published: August 2004

Fatty acids, the most abundant class of soil lipids, indicate pedogenetic processes and soil management. However, their quantitative distribution in organo‐mineral particle‐size fractions is unknown. The concentrations of n‐C10:0 to n‐C34:0 fatty acids both in whole soil samples and in the organo‐mineral particle‐size fractions of the Ap horizon of a Chernozem were determined (i) to evaluate the effects of long‐term fertilization and (ii) to investigate their influence on the aggregation of organo‐mineral primary particles. Quantification by gas chromatography/mass spectrometry (GC/MS) showed that long‐term fertilization with nitrogen, phosphorus and potassium (NPK) and farmyard manure (FYM) led to larger concentrations (25.8 µg g−1) of fatty acids than in the unfertilized sample (22.0 µg g−1). For particle‐size fractions of the unfertilized soil, the fatty acid concentrations increased from the coarse silt to the clay fractions (except for fine silt). Fertilization with NPK and FYM resulted in absolute enrichments of n‐C21:0 to n‐C34:0 fatty acids with a maximum at n‐C28:0 in clay (×2.2), medium silt (×2.0), coarse silt (×1.8) and sand (×2.9) compared with the unfertilized treatment (the factors of enrichment are given in parentheses). New evidence for the aggregate stabilizing function of n‐C21:0 to n‐C34:0 fatty acids was shown by the characteristic pattern in size‐fractionated, disaggregated and aggregated samples. Highly significant correlations of fatty acid concentrations with organic C concentrations and specific surface areas are interpreted as indicators of (i) trapping of fatty acids in organic matter macromolecules and (ii) direct bonding to mineral surfaces. This interpretation was supported by the thermal volatilization and determination of fatty acids by pyrolysis‐field ionization mass spectrometry (Py‐FIMS).
Quantifying the effects of aggregation, particle size and components on the colour of Mediterranean soils
Authors: SÁnchez‐Marañón M. , Soriano M. , Melgosa M. , Delgado G. , Delgado R.
Published: August 2004

Aggregation, particle size, and chemical composition affect the colour of the soil. We have attempted to quantify and understand these effects in 12 Mediterranean soils. We measured the CIELAB colour variableshab,L*, andC*abin aggregated and dispersed soil samples, and also in coarse sand, fine sand, silt, and clay samples before and after sequential removal of organic matter, carbonates, and Fe oxides. Grassmann's colour‐mixing equations adjusted by regression analysis described the colour of the dispersed soil from its particle‐size fractions with an error of 1% forhab, 4% forL*, and 9% forC*ab. This suggests that the contribution of each fraction to the colour of the dispersed soil can be accurately calculated by its colorimetric data weighted by its content and a regression coefficient, which was greatest for clay. We inferred the influence of a component within each fraction by measuring the colour changes after its removal. Iron oxides reducedhabof the silicated substrate by 19%, reducedL* by 12%, and increasedC*abby 64% in all particle‐size fractions. Carbonates and organic matter had little influence: the former because they impart little colour to the silicates and the latter because there was little of it. The CIELAB colour‐difference between dispersed and aggregated soil (mean ΔE*ab = 15.3) was due mainly to ΔL* (−14.7). Aggregation contributed to diminishingL* of dispersed soil by 34%. Scanning electron microscopy showed that Fe oxides and organic coatings cover the surface of aggregates thereby influencing soil colour.
Water repellency of volcanic ash soils from Ecuadorian páramo: effect of water content and characteristics of hydrophobic organic matter
Authors: Poulenard J. , Michel J.C. , Bartoli F. , Portal J.M. , Podwojewski P.
Published: August 2004

Water repellency of volcanic ash soils from the Ecuadorian páramo was studied by a combination of extraction and analysis of water‐repellent products, Molarity Ethanol Droplet values, water contact‐angle measurements by capillary rise, and N2 adsorption isotherms. The undried samples studied are hydrophilic, but exhibit water repellency after moderate drying (48 hours at 30°C). The advancing water contact‐angle measured by capillary rise varies from 78° to 89°. These water contact‐angles decrease strongly after extraction of organic materials by an isopropanol–water mixture. Elemental analysis, infrared spectra and gas chromatography‐mass spectrometry analyses were used to characterize the extracts. The results show that long‐chain fatty acids and more complex non‐polar alkyl components (waxes) are the main water‐repellent materials. The deposition of such extracted materials onto hydrophilic sand leads to the rapid increase of water contact‐angle until values close to those measured on the soil samples are achieved. Assuming a coating of the mineral surface by organic hydrophobic products and using Cassie's law, the water contact‐angle of extracted materials was computed. The values ranged from 100° to 157°. Nitrogen specific surface areas of the soils studied were very small, indicating a low adsorbent–adsorbate interaction on hydrophobic surfaces. These results partially validate the hypothesis of water‐repellent materials that occur as coatings at least after a drying process.
Analysing spatially intermittent variation of nitrous oxide emissions from soil with wavelets and the implications for sampling
Authors: Lark R. M. , Milne A. E. , Addiscott T. M. , Goulding K. W. T. , Webster C. P. , O'Flaherty S.
Published: August 2004

Emissions of gases from the soil are known to vary spatially in a complex way. In this paper we show how such data can be analysed with the wavelet transform. We analysed data on rates of N2O emission from soil cores collected at 4‐m intervals on a 1024‐m transect across arable land at Silsoe in England. We used a thresholding procedure to represent intermittent variation in N2O emission from the soil as a sparse wavelet process, i.e. one in which most of the wavelet coefficients are not significantly different from zero. This analysis made clear that the rate of N2O emission varied more intermittently on this transect than did soil pH, for which many more of the wavelet coefficients had to be retained. This account of intermittent variation motivated us to consider a class of random functions, which we call wavelet random functions, for the simulation of spatially intermittent variation. A wavelet random function (WRF) is an inverse wavelet transform of a set of random wavelet coefficients with specified variance at each scale. We generated intermittent variation at a particular scale in the WRF by specifying a binormal process for the wavelet coefficients at this scale. We showed by simulation that adaptive sampling schemes are more efficient than ordinary stratified random sampling to estimate the mean of a spatial variable that is intermittent at a particular scale. This is because the sampling can be concentrated in the more variable regions. When we simulated values that emulate the intermittency of our data on N2O we found that the gains in efficiency from simple adaptive sampling schemes were small. This was because the emission of N2O is intermittent over several disparate scales. More sophisticated adaptive sampling is needed for these conditions, and it should embody knowledge of the relevant soil processes.