bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Programming over Context-Free Languages with Linear Constraints for the Knapsack Problem: First Results
Authors: Bruhn Peter , Geyer-Schulz Andreas
Published: July 2002

In this paper, we introduce genetic programming over context-free languages with linear constraints for combinatorial optimization, apply this method to several variants of the multidimensional knapsack problem, and discuss its performance relative to Michalewicz's genetic algorithm with penalty functions. With respect to Michalewicz's approach, we demonstrate that genetic programming over context-free languages with linear constraints improves convergence. A final result is that genetic programming over context-free languages with linear constraints is ideally suited to modeling com-plementarities between items in a knapsack problem: The more complementarities in the problem, the stronger the performance in comparison to its competitors.
Stigmergy, Self-Organization, and Sorting in Collective Robotics
Authors: Holland Owen , Melhuish Chris
Published: July 2002

Many structures built by social insects are the outcome of a process of self-organization, in which the repeated actions of the insects interact over time with the changing physical environment to produce a characteristic end state. A major mediating factor is stigmergy, the elicitation of specific environment-changing behaviors by the sensory effects of local environmental changes produced by previous behavior. A typical task involving stigmergic self-organization is brood sorting: Many ant species sort their brood so that items at similar stages of development are grouped together and separated from items at different stages of development. This article examines the operation of stigmergy and self-organization in a homogeneous group of physical robots, in the context of the task of clustering and sorting Frisbees of two different types. Using a behavioral rule set simpler than any yet proposed for ant sorting, and having no capacity for spatial orientation or memory, the robots are able to achieve effective clustering and sorting showing all the signs of self-organization. It is argued that the success of this demonstration is crucially dependent on the exploitation of real-world physics, and that the use of simulation alone to investigate stigmergy may fail to reveal its power as an evolutionary option for collective life forms.
The IPAT Equation and Its Variants
Authors: Chertow Marian R.
Published: July 2002

In the early 1970s Ehrlich and Holdren devised a simple equation in dialogue with Commoner identifying three factors that created environmental impact. Thus, impact (I) was expressed as the product of (1) population, (P); (2) affluence, (A); and (3) technology, (T). This article tracks the various forms the IPAT equation has taken over 30 years as a means of examining an underlying shift among many environmentalists toward a more accepting view of the role technology can play in sustainable development. Although the IPAT equation was once used to determine which single variable was the most damaging to the environment, an industrial ecology view reverses this usage, recognizing that increases in population and affluence can, in many cases, be balanced by improvements to the environment offered by technological systems.
Market Processes and the Closing of ’Industrial Loops’
Authors: Desrochers Pierre
Published: July 2002

Many industrial ecologists assume that traditional economic development was characterized by a linear approach in which materials and energy were extracted, processed, used, and dumped in a linear flow into, through, and out of the economy. Much historical evidence, however, indicates that industrial resource recovery was much more widespread than currently thought. This article reviews the available evidence by introducing the reader to earlier literature on the topic and by providing a short case study of animal by‐products recovery from the Neolithic period to the middle of the twentieth century. The main finding of this article is that the belief that market actors systematically failed to close “industrial loops” in earlier eras is inaccurate. Furthermore, it is pointed out that the industrial ecology metaphor was actually well understood in the middle of the nineteenth century.
Trade and Environment in the World Trading System: A Decade of Stalemate?
Authors: Williams Marc
Published: July 2002

This article assesses the first decade of the trade-environment debate, and explores the possibilities for reconciliation of competing positions on trade-environment issues. It explores three aspects of the continuing conflict over trade and environment in the World Trade Organization. Rejecting both optimistic and pessimistic accounts of the past and future of the trade-environment debate it argues that important changes have occurred that have transformed the debate. But, despite the normalization of the trade-environment debate around the concept of sustainable development significant points of contention remain among the various participants.
DIONYSOS' ROLES IN ARISTOPHANES' FROGS
Authors: Habash Martha
Published: July 2002

In

Frogs

Aristophanes both tests new parameters of Old Comedy and also strengthens existing ones. From the start, Dionysos is preoccupied with literary technique, style, and content. While Dionysos is a common and suitable figure in Old Comedy, the poet is not satisfied just to explore the comic possibilities of god

qua

comic hero/actor. Instead, Aristophanes has Dionysos exchange acting and festival roles while remaining visibly as the god Dionysos, and thereby essentially celebrate his own festival. As such, the god by playing the various roles of the participants of his festival provides unity to the seemingly disparate structure of the play. Furthermore, by bringing the patron of drama onto the stage in this comedy so concerned with literary techniques and merit, Aristophanes adds some authority to his own ideas, spoken or enacted by the god in his various roles, concerning literature.
UNIVERSALS, GENERAL TERMS AND THE COMPARATIVE STUDY OF RELIGION
Authors: Jensen Jeppe Sinding
Published: July 2002

A comparative study of religion rests on comparison and generalization. Both require that the object of study, the subject matters of various religions have something in common - certain properties that warrant their juxtaposition in analyses. If they had nothing in common, "the study" of religion would not make any sense. But it seemingly does, thus "religions" presumably form a subject matter with certain regularities. Such regularities may be "emic universals" on the level of socio-cultural formations and they may be "etic universals" on the levels of the analysts' stock of general terms - and the two levels are connected. This article focuses mainly on the role of universals as general concepts in method and theory, i.e., on the status and use of etic level generalizations such as models, maps, metaphors that are constructed in order to explain and make sense, as general terms, of emic level entities, properties, functions, structures etc. The last part concerns the use of universals in four modes of comparison of material, cognitive and symbolic matters.
FILIAL SOCIAL BOND FORMATION IN FRY OF THE MATERNAL MOUTHBROODING TILAPIA (PISCES: CICHLIDAE): A COMPARATIVE STUDY
Authors: Russock Howard
Published: July 2002

The mother - fry relationship in the maternal mouthbrooding species of tilapia has become a model of social bond formation in fish because of the relatively extensive care given to the young. This relationship has been extensively studied in Oreochromis mossambicus. In order to determine if the response pattern observed in O. mossambicus fry has broader applications, the critical experiments of these studies were replicated in two closely related species of maternal mouthbrooding tilapia, O. niloticus and O. esculentus. All fry used in the study were removed from their mother's mouth as eggs and hatched artificially in groups. The fry were also exposed to maternal models in groups, but all fry in the study were tested for their responsiveness or preferential behaviour to maternal models individually. Experiment I determined the responsiveness of fry naive to maternal models in order to establish a baseline for future comparisons. O. niloticus fry exhibited a significant decline in responsiveness to models between days 11 and 12 post-hatching while O. esculentus fry exhibited a significant decline between days 16 and 18, suggesting the possible existence of a sensitive period in these two species. In order to obtain evidence for the existence of a sensitive period, naive fry of both species in Experiment II were exposed to maternal models at their peak of responsiveness and then tested at a later age at which responsiveness in naive fry had fallen significantly. In 15 of the 18 comparisons involving the two species, exposure to a maternal model at the peak of responsiveness for naive fry prevented the later decline in responsiveness. Experiment III examined whether experience with maternal models effected how exclusively fry responded to such models in the future. It was predicted that, like O. mossambicus fry, experienced fry of both species would exhibit a decline in responsiveness to models that formed at least a partial mismatch with the fry's initial schema for maternal stimuli. This prediction was not supported. Experiment IV examined preferential behaviour. It was predicted that fry exposed to a maternal model would later behave preferentially toward whichever model of a pair formed a closer match with their schema, and not necessarily toward the model to which they had been previously exposed. Maternally naive fry were not expected to behave preferentially. These predictions were generally supported, although the effect was less vigorous or consistent than in O. mossambicus. Filial social bond formation in these species of maternal mouthbrooding tilapia appears to be characterized by strong predispositions for maternally relevant visual stimuli which require appropriate experience for their maintenance and for the induction of preferences. Since a similar developmental pattern in seen in (e.g.) song learning in passerine birds, imprinting in precocial birds and filial following in substrate spawning cichlid fish, the phenomenon appears to be of broad significance.
Differential behaviour of the survival stages of Nacobbus aberrans (Nemata: Pratylenchidae) under sub-optimal environments
Authors: Souza Ricardo , Baldwin James
Published: July 2002

The biology of Nacobbus aberrans is poorly understood, including the
behaviour of third and fourth stage juveniles (J3 and J4) under sub-optimal
environmental conditions. To assess the effect of such conditions on J3 and
J4, tomato plants infected by N. aberrans were grown under optimal
conditions, and then were submitted to sub-optimal day length and
temperature during the periods when J3 or J4 predominated in the population.
Even under optimal conditions, some J4 became quiescent. The suboptimal
conditions prevented both J3 and J4 moults, and affected nematode
development when optimal conditions were restored: the J3 immediately
moulted into J4, but many J4 remained quiescent and did not moult to the
adult stage. These unanticipated differences in how J3 and J4 endured
unfavourable conditions suggest that the latter stage is better adapted for
survival. Die Biologie von Nacobbus aberrans ist noch wenig bekannt,
einschliesslich des Verhaltens der Juvenilstadien drei und vier (J3 und J4)
unter suboptimalen Umweltbedingungen. Um die Wirkung solcher Bedingungen auf
J3 und J4 zu prüfen, wurden mit N. aberrans infizierte Tomatenpflanzen
zunächst unter optimalen Bedingungen gehalten und dann, wenn J3 und J4 in
der Population vorherrschten, suboptimalen Tageslängen und
Temperaturbedingungen unterworfen. Auch unter optimalen Bedingungen fielen
einige J4 in den Ruhezustand. Die suboptimalen Bedingungen verhinderten die
Häutungen von J3 und J4 und beeinträchtigten die Nematodenentwicklung auch
dann, wenn wieder optimale Bedingungen hergestellt wurden: die J3 häuteten
sich sofort zu J4, aber viele J4 verharrten im Ruhezustand und häuteten sich
nicht zu Adulten. Diese unerwarteten Unterschiede zwischen J3 und J4 in
bezug auf das Überstehen ungünstiger Bedingungen lassen vermuten, dass das
J4-Stadium besser für das Überleben angepasst ist.
Morphological variation between allopatric populations of Steinernema kraussei (Steiner, 1923)(Rhabditida: Steinernematidae)
Authors: Stock S. Patricia , Mrácek Zdenek , Webster John
Published: July 2002

Morphometrics of four Canadian, three US and two European isolates representing distinct geographic populations of Steinernema kraussei (Steiner, 1923) were compared and analysed by multivariate analysis. A total of 540 individuals (270 males and 270 third-stage infective juveniles) representing the nine populations was measured. Fourteen morphometric variables were selected and subjected to principal component and canonical analyses. Results from both analyses indicate that there are morphological differences among the studied isolates, and that these differences are congruent with their geographic origin. The European isolates were shown to be distinctly different from the North American isolates. Within the North American isolates, the western isolates were distinguished from the eastern one (Parishville). No significant differences were observed between the two European isolates studied. Ont été comparées et étudiées par analyse multivariable les caractéristiques morphométriques de quatre isolats canadiens, trois isolats américains et deux isolats européens représentant des populations géographiques distinctes de Steinernema kraussei. Un total de 540 individus (270 mâles et 270 juvéniles infestants de troisième stade) représentant les neuf populations a été mesuré. Quatorze variables morphométriques ont été sélectionnées et soumises à des analyses en composantes principales et canonique. Les résultats des deux analyses montrent qu’il existe des différences morphologiques entre les isolats étudiés et que ces différences sont congruentes avec leur origine géographique. Les isolats européens sont apparus comme étant nettement différents des isolats nordaméricains. Dans le groupe des isolats nord-américains, les isolats de l’ouest ont été différenciés de celui de l’est (Parishville). Aucune différence significative n’a été observé entre les deux isolats européens étudiés.
The nematicidal effects of the bacteria Pseudomonas oryzihabitans and Xenorhabdus nematophilus on the root-knot nematode Meloidogyne javanica
Authors: Samaliev Harry , Andreoglou Fotini , Elawad Sami , Hague Nigel , Gowen Simon
Published: July 2002

In two laboratory experiments and one pot experiment the influence of the
bacterial symbionts Pseudomonas oryzihabitans from Steinernema abbasi and
Xenorhabdus nematophilus from S. carpocapsae on the root-knot nematode
Meloidogyne javanica was investigated. Exposure of egg masses of M. javanica
to the bacteria and their metabolites resulted in reduced hatching of second
stage juveniles (J2). J2 in contact with the bacteria and their metabolites
exhibited disorientation and convulsive movements, but when they were washed
and placed in fresh water, many regained normal movement. At dosages of 106
and 107 cells ml-1 mortality was 100% after 24 h exposure, Xenorhabdus being
more toxic than Pseudomonas. In soil X. nematophilus was ineffective but
P.oryzihabitans prevented invasion of J2 into tomato roots and there was
evidence that the bacterium or its metabolites interfered with nematode
development in galls. Overall, the results indicate that P.oryzihabitans may
provide a possible control strategy for root-knot nematodes. Action
nématicide des bactéries Pseudomonas oryzihabitans et Xenorhabdus
nematophilus sur le nématode Meloidogyne javanica - Les présentes
recherches, au travers de deux expériences au laboratoire et d'une troisième
en pots, ont concerné l'influence sur le nématode Meloidogyne javanica des
symbiontes bactériens Pseudomonas oryzihinabitans, provenant de Steinernema
abbasi, et Xenorhabdus nematophilus, de S. carpocapsae. L'exposition de
masses d'œufs de M. javanica aux bactéries et à leurs métabolites a provoqué
une diminution de l'éclosion des juvéniles de deuxième stade (J2). Les J2 en
contact avec les bactéries et leurs métabolites se sont montrés désorientés
et sujets à des mouvements convulsifs mais, après qu'ils aient été lavés et
placés dans une eau pure, bon nombre d'entre eux ont recouvré des mouvements
normaux. Aux doses de 106 et 107 cellules/ml-1 la mortalité était de 100%
après une exposition de 24 h, Xenorhabdus s'étant révélé plus toxique que
Pseudomonas . Dans le sol, Xenorhabdus s'est montré inefficace tandis que
Pseudomonas empêchait la pénétration des J2 dans les racines de tomate; de
plus, il semblerait évident que les bactéries ou leurs métabolites aient une
influence sur le développement des nématodes dans les galles. Dans
l'ensemble, les résultats indiquent que P.oryzihinabitans peut fournir une
éventuelle stratégie de contrôle envers les Meloidogyne.
Meloidogyne chitwoodi and M. fallax protein variation assessed by two-dimensional electrophoregram computed analysis
Authors: Tastet Christophe , Bossis Michel , Gauthier Jean-Pierre , Renault Lionel , Mugniery Didier
Published: July 2002

The variation of total soluble protein extracts from white adult females of seven Meloidogyne chitwoodi and three M. fallax isolates were studied using two dimensional gel electrophoresis (2-DGE). The 2-D protein profiles were compared with a computed analysis system. A synthetic image or 'master' was constructed from proteinic spots present in each isolate. The comparison of the two species allowed detection of qualitative and, to a lesser extent, quantitative variations. Among the 243 proteinic spots present on the master, we have identified 75 monomorphic spots for both species and nine discriminative proteins for each of the two species. In addition, two isoelectric point variants and two quantitative variants were observed. The similarity index and the genetic distances between the ten isolates were calculated on the basis of homologous polymorphic spots. Dendrograms were constructed according to the UPGMA method. Significance of the results from the phenetic study was assessed by bootstrap analysis. The results from the clustering analysis allowed differentiation between both species and showed intraspecific variation among the M. chitwoodi isolates equal to that among the M. fallax isolates. Variabilite proteique de Meloidogyne chitwoodi et M. fallax etudiee par analyse informatisee d'electrophoregrammes bidimensionnels - La variabilite d'extraits proteiques solubles totaux de femelles blanches adultes de sept isolats de Meloidogyne chitwoodi et trois de M. fallax a ete etudiee par electrophorese sur gel en deux dimensions (2-DGE). Les profils proteiques bidimensionels ont ete compares grace a un systeme d'analyse informatise. Une image synthetique, ou image de reference, a ete construite a partir des spots proteiques toujours observes dans chaque isolat. La comparaison des deux especes a permis de detecter des variations qualitatives et, dans une moindre mesure, quantitatives. Parmi les 243 taches proteiques presentes sur l'image de reference, ont ete identifies 75 polypeptides communs aux deux especes et neuf proteines discriminantes pour chacune des deux especes. De plus, deux variants de point isoelectrique et deux variants quantitatifs ont ete observes. Les indices de similarite et les distances genetiques entre les dix isolats ont ete etudies a partir des taches polymorphes homologues. Les dendrogrammes ont ete construits selon la methode UPGMA. La signification des resultats phenetiques a ete estimee par une analyse "bootstrap". Les resultats de l'analyse en grappes ont permis de differencier les deux especes et ont revele une variabilite intraspecifique similaire entre isolats de M. chitwoodi et isolats de M. fallax.
Dehydroxylation of Fe3+ , Mg-rich dioctahedral micas: (II) cation migration
Authors: Muller F. , Drits V. A. , Tsipursky S. I . , Plançon A.
Published: July 2002

The quantitative interpretation of the reflection intensities of the SAED patterns of glauconites reveals the mechanism of migration of the octahedral sheet cations during heating up to 750°C. It confirms that Mg2+ has a greater ability than Fe3+ to migrate from cis-to trans-sites, as previously found by means of XRD pattern modelling. For samples heated to 650°C, the two formerly vacant trans-sites in the base-centred unit-cell become occupied, but differently, which leads to a primitive unit-cell, and the cis-sites remain filled almost entirely by Fe3+ only. The cation migration occurs through the nearest shared edges in the [010] and [310] directions. The samples heated to 750°C reveal a base-centred super-cell with A = 3a and B = b. All Mg cations leave the cis-sites to occupy completely four of the six available trans-sites of the super-cell. Migration also occurs through the shared edges in the [010] and [310] directions. The primitive unit-cell is not an intermediate step in the migration process leading to the super-cell. The existence of additional satellites in the SAED patterns of some crystals heated to 750°C corresponds to the existence of antiphase domains with a 3b/2 width and an antiphase shift of a/2.
Clay mineral and organic diagenesis of the Lower Oligocene Schöneck Fishshale, western Austrian Molasse Basin
Authors: Gier S.
Published: July 2002

The ‘Fischschiefer formation’ has been identified as the likely source rock for petroleum in the western Molasse Basin of Austria. The investigated cores originate from different depths (1242 m to 4294 m) of the Fischschiefer horizon. The illitization observed in the <0.2 μm fraction proceeds slowly, probably because of the low geothermal gradient (3°C/100 m) in the Molasse Basin. The illite content in illite-smectite ranges from 30% (randomly ordered) for the shallowest sample to 65% (R0+R1 ordering) for the deepest sample. The oxygen index (OI) vs. hydrogen index (HI) plot implies type I to II kerogen for the organic matter. Vitrinite reflectance and Rock Eval parameters indicate an immature stage in the diagenesis of kerogen. Only the deepest sample (4294 m, 0.6% Rr) reaches the early oil window. There is a good correlation of the illitization trend of the mixed-layer mineral I-S and the organic maturity parameters.
Mechanical properties of North Sea Tertiary mudrocks: investigations by triaxial testing of side-wall cores
Authors: Wensaas L. , Aagaard P. , Berre T. , Roaldset E.
Published: July 2002

In the North Sea Tertiary section, wellbore instability problems are frequently reported in Palaeocene-Early Oligocene smectite-rich mudrocks. Analysis of the mechanical properties of these Tertiary mudrocks is generally hampered by the lack of suitable core material. This study represents an attempt to study the geomechanical behaviour of mudrocks by triaxial tests of side-wall cores obtained from the borehole wall. The tests performed include measuring the changes in pore pressure during shearing and undrained shear strength in specimens initially consolidated to in situ effective stress levels. The coefficients of permeability (kf), estimated from the consolidation time behaviour range from 2.6 x 10-11 to 2.4 x 10-12 m/s. The tested cores behaved like slightly overconsolidated to normally consolidated materials with an initial near constant volume (elastic behaviour) for low deviatoric load followed by an increasingly contractant behaviour approaching failure. Compared with results from onshore analogues, the strength properties of the investigated mudrocks appear to be related to their content of expandable clay minerals. A wellbore stability chart to forecast adequate drilling fluid pressures for future wells has been developed by the use of linear (Mohr-Coulomb) failure criteria based on the peak strength data. It is demonstrated that side-walt cores can provide satisfactory test materials for rock mechanical analysis, and their use may serve to improve our knowledge of the rock mechanical behaviour of typically troublesome mudrocks for which no conventional cores are available.
The origin and formation of clay minerals in soils: past, present and future perspectives
Authors: Wilson M. J.
Published: July 2002

The origin and formation of soil clay minerals, namely micas, vermiculites, smectites, chlorites and interlayered minerals, interstratified minerals and kaolin minerals, are broadly reviewed in the context of research over the past half century. In particular, the pioneer overviews of Millot, Pedro and Duchaufour in France and of Jackson in the USA, are considered in the light of selected examples from the huge volume of work that has since taken place on this topic. It is concluded that these early overviews may still be regarded as being generally valid, although it may be that too much emphasis has been placed upon transformation mechanisms and not enough upon neoformation processes. This review also highlights some of the many problems pertaining to the origin and formation of soil clays that remain to be resolved.
Clay formation and podzol development from postglacial moraines in Switzerland
Authors: Righi D. , Huber K. , Keller C.
Published: July 2002

The fine silt (2–5 μm) and fine clay (<0.1 μm) fractions from four acid soils developed from moraines of increasing age (80, 400, 3,000 and 6,500 years old) in Switzerland, were studied by X-ray diffraction and chemical analyses. The soil parent material is homogeneous at the four sites and the soils can be considered as forming a chronosequence of soil development leading to the formation of Podzols. Mineralogical evolution of silt-sized phyllosilicates and fine clay fractions follows different pathways according to their composition and the soil horizon in which they are located. Dioctahedral and trioctahedral minerals in the soil parent material were both weathered in the Bw and Bs horizons but the trioctahedral phase more strongly and faster than the dioctahedral one. Weathering products are mica-vermiculite mixed-layers, vermiculite and finally gibbsite and Fe oxy-hydroxides. Weathering of the trioctahedral fraction was faster in the eluvial A or E horizons than in the B horizons, being almost complete after 3,000 years of soil development. Appreciable weathering of the dioctahedral fraction occurs only in the eluvial horizons leading to the formation of mica-smectite mixed-layers and smectite. Although smectite has been reported in the E horizon of Podzols in different environments, the significant finding in this work is the presence of this mineral in soils developed from the same parent material. This supports the fact that smectite is the end- product of mica alteration in strongly leached and acidified E horizons of Podzols.
Geochemistry of mantle-related intermediate rocks from the Tibbit Hill volcanic suite, Quebec Appalachians
Authors: Abdel-Rahman Abdel-Fattah M. , Kumarapeli P. Stephen
Published: July 2002

We present a study on major and trace element geochemistry of some intermediate lithologies from the predominantly basaltic Tibbit Hill volcanic suite in the Humber Zone of the Quebec Appalachians. The intermediate rocks probably formed as lava flows in the volcanic sequence. Their presence shows that this rift-related, c. 554 Ma volcanic sequence is not bimodal (basaltic-comenditic) as previously thought, but consists of a spectrum of compositions ranging from mafic through intermediate to felsic lithologies. The entire volcanic sequence is poly-deformed and generally metamorphosed to greenschist facies conditions.

The intermediate rocks of the Tibbit Hill Formation are trachyandesitic, trachytic and comenditic in composition, and exhibit a wide range of SiO2 content (52 to 68 wt.%). Mg is highly depleted in most samples. Variations of silica versus the alkalis show that most of the samples are alkaline in nature. The rocks display a tholeiitic trend on a standard AFM diagram.

In general, the examined rocks also exhibit a wide range of Sr (15 to 174 ppm), Rb (0 to 156 ppm), Zr (155 to 899 ppm), Nb (18 to 123 ppm), and Y (18 to 94 ppm). The concentration of Hf and Ta are generally low (6.6–14.8 ppm, and 3.3–6.6 ppm, respectively), compared to those of Zr and Nb. Nevertheless, these rocks contain relatively high concentrations of the HFS elements, thus reflecting an enriched source. The suite is also relatively enriched in the rare earth elements (REE), and exhibits fractionated, subparallel REE pattems; the latter are generally uniform and conformable.

Chemical features of these volcanic rocks are typical of those of anorogenic A1 type suites, related to hotspots, mantle plumes, or continental rift zones. This is consistent with earlier interpretation of volcanism associated with an Iapetan RRR triple junction, occurring shortly before the onset of seafloor spreading. At that stage of crustal evolution, alkaline to transitional basaltic magma pierced into the crust, and experienced fractionation to produce the liquids of intermediate composition. Rare earth element geochemical modelling supports the hypothesis that the most evolved composition for which REE data are available (comendite; 67.9 wt.% SiO2) was produced by 20% fractional crystallization of the least evolved trachyandesite (56.7 wt.% SiO2) of this intermediate volcanic assemblage.
Incorporation of ferric iron in CaSiO3 perovskite at high pressure
Authors: Wang Zhongwu , Yagi T.
Published: July 2002

Synthetic andradite (Ca3Fe2Si3O12) has been compressed to loading pressures >21 GPa and heated to ∼1000°C by a YAG laser in a Diamond Anvil Cell (DAC). After quenching to room temperature, X-ray diffraction of the sample, still held at 21 GPa, showed that andradite had transformed to a cubic perovskite type polymorph with a = 3.460(4) Å. Upon decompression the perovskite phase transformed into an amorphous phase. The density of the perovskite polymorph (Ca3Fe2Si3O12) is ∼13.6% greater than that of isochemical andradite at 21 GPa. Ferric iron replaces Ca2+ and Si4+ in the perovskite structure (Fe3+ + Fe3+ = Si4+ + Ca2+), giving a formula unit: (Ca,Fe3+)(Si,Fe3+)O3. The new Fe3+-rich Ca-perovskite may provide new insight into the controls on the electrical conductivity of the lower mantle.
Palladium oxides in ultramafic complexes near Lavatrafo, Western Andriamena,
Madagascar
Authors: McDonald I. , Ohnenstetter D. , Ohnenstetter M. , Vaughan D. J.
Published: July 2002

Small (<2 km diameter), ultramafic intrusive complexes in the Andriamena
region of Madagascar contain zones with disseminated chromite and sulphides which
carry high concentrations of platinum-group elements (PGE). Assay of drill core
from one complex, designated UM2, revealed three zones showing consistently high
PGE grades. Mineralogical investigation of the UM2 core reveals that a small
number of low reflecting, Pd-bearing platinum-group minerals (PGM) are present —
always in association with a poorly characterized Pd stibio-arsenide
[Pd3(Sb,As)] phase — in the shallowest of the three zones.
Electron microprobe analysis of these PGM indicates the presence of oxygen and
that at least two species exist. The resulting stoichiometries suggest that at
least one species could be a hydrated form of palladinite
[PdO.(H2O)n]. The other phase could
be a hydroxide [Pd(OH)2] or a less strongly hydrated form of
palladinite. Textural evidence suggests that the Pd-O species formed via the
replacement of a precursor Pd-rich PGM, with only a limited removal of Pd, rather
than via precipitation of a Pd-O PGM from a fluid that was Pd-bearing. The limited
thermal stability of hydrated Pd oxides and the apparent restriction of the Pd-O
phases to a shallow zone which is affected by the seasonal movement of
groundwater, suggests that they may have formed at low temperatures via the
leaching and replacement of other elements from a precursor Pd-rich PGM by oxygen
and water during alternating water-saturated and dry conditions. If this is the
case, the water table interface might be another environment, in addition to the
surface, in which to look for the development of PGE oxides.
Unequilibrated assemblages of sulphide, metal and oxide in the fusion crusts
of the enstatite chondrite meteorites
Authors: Genge M. J. , Grady M. M.
Published: July 2002

The fusion crusts of meteorites form due to heating during atmospheric entry
and have mineralogies which are strongly influenced by changes in oxidation state.
We have studied the fusion crusts of the most reduced primitive meteorite group,
the enstatite chondrites, since they should demonstrate pronounced changes on
oxidation. The fusion crusts are dominated by highly unequilibrated assemblages of
sulphide, metal and oxide with compositions indicative of progressive oxidation by
the reaction with atmospheric oxygen. Troilite becomes depleted in Ti, Cr and Mn,
and enriched in Ni with increasing oxidation. Enrichments in the Ni-contents of
kamacite and depletions in Si-content also occur with oxidation, although
contemporaneous enrichments in Si within metal droplets occurs by partial melting.
Assemblages dominated by Fe-oxide are found within fusion crusts as reaction rims
on metal, as veins and within troilite-metal assemblages as droplets and formed by
oxidation of metal during heating. Despite the evidence for large increases in
redox state during heating, fusion crusts also contain lithophile sulphides
indicating a high degree of disequilibrium during the atmospheric reprocessing of
enstatite chondrite materials. Based on comparisons with experimental phase
relations, ablation rates of 0.08–0.25 cm s−1 are predicted
from the thermal gradients recorded in fusion crusts; these rates are broadly
similar to those suggested for other meteorite groups.
Expression profile of MUM1/IRF4, BCL-6, and CD138/syndecan-1 defines novel histogenetic subsets of human immunodeficiency virus–related lymphomas
Authors: Carbone Antonino , Gloghini Annunziata , Larocca Luigi M. , Capello Daniela , Pierconti Francesco , Canzonieri Vincenzo , Tirelli Umberto , Dalla-Favera Riccardo , Gaidano Gianluca
Published: July 2002

This study was aimed at defining the histogenesis of the pathologic spectrum of lymphoma arising in the context of human immunodeficiency virus (HIV) infection. Toward this aim, 87 AIDS-related non-Hodgkin lymphomas (AIDS-NHL) and 16 Hodgkin lymphomas arising in HIV+ patients (HIV-HL) were comparatively analyzed for the expression pattern of several B-cell histogenetic markers, including BCL-6 (expressed by centroblasts and centrocytes), MUM1/IRF4 (expressed by late centrocytes and post–germinal center [GC] B cells), and CD138/syn-1 (expressed by post-GC B cells). Expression of MUM1, BCL-6, and syn-1 segregated 3 major phenotypic patterns among AIDS-NHL and HIV-HL: (1) the BCL-6+/MUM1−/syn-1− pattern, selectively clustering with a large fraction of AIDS-Burkitt lymphoma (17 of 19) and of systemic AIDS–diffuse large cell lymphoma (12 of 16); (2) the BCL-6−/MUM1+/syn-1−pattern, associated with a fraction of AIDS-immunoblastic lymphoma (8 of 24); and (3) the BCL-6−/MUM1+/syn-1+ pattern, associated with systemic and primary central nervous system immunoblastic lymphoma (14 of 24) and with primary effusion lymphoma (10 of 10), plasmablastic lymphoma of the oral cavity (7 of 7), and HIV-HL (15 of 16). Analysis of nonneoplastic lymph nodes showed that the 3 phenotypic patterns detected in AIDS-NHL and HIV-HL correspond to distinct stages of physiologic B-cell development—centroblasts (BCL-6+/MUM1−/syn-1−), late GC/early post-GC B cells (BCL-6−/MUM1+/syn-1−), and post-GC B cells (BCL-6−/MUM1+/syn-1+). Expression of the Epstein-Barr virus-encoded latent membrane protein-1 clustered with the BCL-6−/MUM1+/syn-1+profile throughout the clinicopathologic spectrum of AIDS-NHL and HIV-HL. Overall, these results define novel histogenetic subsets of AIDS-NHL and HIV-HL and may provide novel tools for refining the diagnosis of these disorders.
Plasminogen-mediated matrix invasion and degradation by macrophages is dependent on surface expression of annexin II
Authors: Falcone Domenick J. , Borth Wolfgang , Khan K. M. Faisal , Hajjar Katherine A.
Published: July 2002

Genetic evidence demonstrates the importance of plasminogen activation in the migration of macrophages to sites of injury and inflammation, their removal of necrotic debris, and their clearance of fibrin. These studies identified the plasminogen binding protein annexin II on the surface of macrophages and determined its role in their ability to degrade and migrate through extracellular matrices. Calcium-dependent binding of annexin II to RAW264.7 macrophages was shown using flow cytometry and Western blot analysis of EGTA eluates. Ligand blots demonstrated that annexin II comigrates with one of several proteins in lysates and membranes derived from RAW264.7 macrophages that bind plasminogen. Preincubation of RAW264.7 macrophages with monoclonal anti–annexin II IgG inhibited (35%) their binding of 125I-Lys-plasminogen. Likewise, plasmin binding to human monocyte-derived macrophages and THP-1 monocytes was inhibited (50% and 35%, respectively) when cells were preincubated with anti–annexin II IgG. Inhibition of plasminogen binding to annexin II on RAW264.7 macrophages significantly impaired their ability to activate plasminogen and degrade [3H]-glucosamine–labeled extracellular matrices. The migration of THP-1 monocytes through a porous membrane, in response to monocyte chemotactic protein-1, was blocked when the membranes were coated with extracellular matrix. The addition of plasminogen to the monocytes restored their ability to migrate through the matrix-coated membrane. Preincubation of THP-1 monocytes with anti–annexin II IgG inhibited (60%) their plasminogen-dependent chemotaxis through the extracellular matrix. These studies identify annexin II as a plasminogen binding site on macrophages and indicate an important role for annexin II in their invasive and degradative phenotype.
Novel structurally altered P2X1 receptor is preferentially activated by adenosine diphosphate in platelets and megakaryocytic cells
Authors: Greco Nicholas J. , Tonon Giovanni , Chen Weidong , Luo Xunyi , Dalal Rakhi , Jamieson G. A.
Published: July 2002

Experimental and clinical data suggest the presence of multiple types of adenosine diphosphate (ADP) receptors, one coupled to ligand-gated cation channels (P2X) and others coupled to G-protein–coupled (P2Y) receptors. This report identifies cDNA for a structurally altered P2X1-like receptor in megakaryocytic cell lines (Dami and CMK 11-5) and platelets that, when transfected into nonresponsive 1321 cells, confers a specific sensitivity to ADP with the pharmacologic rank order of ADP > > ATP > > > α,β-methylene-ATP as measured by Ca++ influx. This receptor (P2X1del) contains a deletion of 17 amino acids (PALLREAENFTLFIKNS) that includes an NFT consensus sequence for N-linked glycosylation. Glycosylated forms of the P2X1deland P2X1wt receptors were indistinguishable electrophoretically by Western blot or by immunoprecipitation using available antihuman and antirat antibodies. These results indicate that the expression of the P2X1del receptor results in an influx of Ca++ induced by ADP. Expression of P2X1delreceptor homomeric subunits is sufficient to express a receptor preferentially activated by ADP and suggests that this altered form, alone or in combination with P2X1wt receptors, is a component of an ADP-activated ion channel.
Type 1 von Willebrand disease mutation Cys1149Arg causes intracellular retention and degradation of heterodimers: a possible general mechanism for dominant mutations of oligomeric proteins
Authors: Bodó Imre , Katsumi Akira , Tuley Elodee A. , Eikenboom Jeroen C. J. , Dong Zhengyu , Sadler J. Evan
Published: July 2002

Some families affected by von Willebrand disease type 1 show high penetrance with exceptionally low von Willebrand factor (VWF) levels. Previously, a mutation associated with this dominant phenotype, Cys1149Arg, was found to decrease the secretion of coexpressed normal VWF, and the mutation was proposed to cause intracellular retention of pro-VWF heterodimers. To demonstrate heterodimer formation, a model was developed in which subunits could be distinguished immunologically and by size. Recombinant VWF lacking domain A1 (dA1), A3 (dA3), or both (dA13) was secreted efficiently as a full range of multimers. Cotransfection of Cys1149Arg and dA13 resulted in the secretion of multimeric VWF containing about 250 kd (Cys1149Arg) and about 210 kd (dA13). Cell lysates contained pro-VWF forms of Cys1149Arg and dA13. Immunoprecipitation with an antidomain A1 antibody recovered both subunits in heterodimers, and subunit ratios were consistent with random dimerization. Similar results were obtained for cotransfection of Cys1149Arg and dA1. Normal VWF has a Cys1149-Cys1169 intrachain bond. When cotransfected with normal VWF, Cys1149Arg or the double mutant Cys1149Arg+Cys1169Ser caused a similar decrease in VWF secretion, suggesting that an unpaired Cys1169 does not explain the intracellular retention of Cys1149Arg. VWF Cys1149Arg was not secreted from BHK cells but was degraded intracellularly within about 4 hours, and the proteasome inhibitor lactacystin delayed its clearance more than 16 hours. Thus, dominant von Willebrand disease type 1 may be caused by heterodimerization of mutant and normal subunits in the endoplasmic reticulum followed by proteasomal degradation in the cytoplasm. A similar dominant negative mechanism could cause quantitative deficiencies of other multisubunit proteins.
Apaf-1 protein deficiency confers resistance to cytochromec–dependent apoptosis in human leukemic cells
Authors: Jia Li , Srinivasula Srinivasa M. , Liu Feng-Ting , Newland Adrian C. , Fernandes-Alnemri Teresa , Alnemri Emad S. , Kelsey Stephen M.
Published: July 2002

The human leukemia cell lines K562, CEM, CEM/VLB100, human leukemic blasts, and the bladder cancer J82 cell line have different sensitivities to UV light–induced apoptosis. It is reported that resistance to UV light–induced apoptosis occurs at a point in the apoptotic pathway upstream of caspase-3 but downstream of mitochondrial cytochrome c release. It is demonstrated that the block is due to deficiency of Apaf-1, a critical member of the apoptosome. Sensitivity to apoptosis was independent of caspase-9b or XIAP (inhibitors of apoptosis proteins) expression or levels of procaspase-9. Transfection of Apaf-1 conferred sensitivity to apoptosis in resistant cells. Apaf-1 deficiency may constitute a significant mode of resistance to apoptosis in human leukemia.
H ferritin knockout mice: a model of hyperferritinemia in the absence of iron overload
Authors: Ferreira Chrystophe , Santambrogio Paolo , Martin Marie-Elise , Andrieu Valérie , Feldmann Gérard , Hénin Dominique , Beaumont Carole
Published: July 2002

Ferritin, the iron-storing molecule, is made by the assembly of various proportions of 2 different H and L subunits into a 24-mer protein shell. These heteropolymers have distinct physicochemical properties, owing to the ferroxidase activity of the H subunit, which is necessary for iron uptake by the ferritin molecule, and the ability of the L subunit to facilitate iron core formation inside the protein shell. It has previously been shown that H ferritin is indispensable for normal development, since inactivation of the H ferritin gene by homologous recombination in mice is lethal at an early stage during embryonic development. Here the phenotypic analysis of the mice heterozygous for the H ferritin gene (Fth+/− mice) is reported, and differences in gene regulation between the 2 subunits are shown. The heterozygousFth+/− mice were healthy and fertile and did not present any apparent abnormalities. Although they had iron-overloaded spleens at the adult stage, this is identical to what is observed in normal Fth+/+ mice. However, these heterozygous mice had slightly elevated tissue L ferritin content and 7- to 10-fold more L ferritin in the serum than normal mice, but their serum iron remained unchanged. H ferritin synthesis from the remaining allele was not up-regulated. This probably results from subtle changes in the intracellular labile iron pool, which would stimulate L ferritin but not H ferritin synthesis. These results raise the possibility that reduced H ferritin expression might be responsible for unexplained human cases of hyperferritinemia in the absence of iron overload where the hereditary hyperferritinemia-cataract syndrome has been excluded.
Human natural killer cells with polyclonal lectin and immunoglobulinlike receptors develop from single hematopoietic stem cells with preferential expression of NKG2A and KIR2DL2/L3/S2
Authors: Miller Jeffrey S. , McCullar Valarie
Published: July 2002

The stage of progenitor maturation and factors that determine the fate and clonal acquisition of human natural killer (NK) cell receptors during development are unknown. To study human NK cell receptor ontogeny, umbilical cord blood CD34+/Lin−/CD38− cells were cultured with a murine fetal liver line (AFT024) and defined cytokines. In the absence of lymphocyte-stimulating cytokines or when contact with AFT024 was prohibited, NK cell progeny were killer immunoglobulinlike receptor (KIR) and CD94 lectin receptor negative. In contrast, efficient NK cell differentiation and receptor acquisition was dependent on direct contact of progenitors with AFT024 and the addition of interleukin-15 (IL-15) or IL-2 but not IL-7. To address the question of whether receptor acquisition was determined at the stem cell level, single CD34+/Lin−/CD38−progenitors were studied. More than 400 single cell progeny were analyzed from cultures containing IL-15 or IL-2 and NK cells were always polyclonal, suggesting that receptor fate is determined beyond an uncommitted progenitor and that receptor-negative NK cells acquire class I-recognizing receptors after lineage commitment. KIR2DL2/L3/S2 was expressed more than KIR2DL1/S1 or KIR3DL1, and NKG2A was the dominant CD94 receptor, independent of whether the stem cell source contained the respective major histocompatibility complex class I ligand, suggesting a nonrandom sequence of receptor acquisition. The conclusion is that NK receptor fate is determined after NK cell commitment, does not require stromal presentation of human class I alleles, and is clonally stable after expression but dynamic because new receptors are acquired over time.
Depletion of circulating natural type 1 interferon-producing cells in HIV-infected AIDS patients
Authors: Soumelis Vassili , Scott Iain , Gheyas Ferdous , Bouhour Damien , Cozon Gregoire , Cotte Laurent , Huang Laurence , Levy Jay A. , Liu Yong-Jun
Published: July 2002

Natural interferon-α producing cells (IPCs) are a newly characterized blood cell type, which is the major source of type I interferons in antiviral innate immune responses. The relationship between the number of circulating IPCs, HIV disease progression, and the occurrence of HIV-related complications was investigated. The study of 25 healthy donors and 54 HIV-infected subjects demonstrated a direct correlation between blood IPC number, interferon-α production, and clinical state of HIV-infected subjects. Asymptomatic long-term survivors had increased IPC number and function relative to uninfected controls and infected individuals with progressive disease. IPC numbers were markedly reduced in AIDS patients developing opportunistic infections and cancer. A negative correlation was found between the IPC number in the blood and the HIV viral load, suggesting that IPCs are important in controlling HIV replication. This study provides the first evidence that IPCs are being affected during the course of HIV infection and suggests that these cells can play a vital role in the protection against opportunistic pathogens and cancer.