bluuebunny/crossref_metadata_2025 huggingface dataset:
A Reinforcement Learning Approach to Online Clustering
Authors: Likas Aristidis
Published: July 2002

A general technique is proposed for embedding online clustering algorithms based on competitive learning in a reinforcement learning framework. The basic idea is that the clustering system can be viewed as a reinforcement learning system that learns through reinforcements to follow the clustering strategy we wish to implement. In this sense, the reinforcement guided competitive learning (RGCL) algorithm is proposed that constitutes a reinforcement-based adaptation of learning vector quantization (LVQ) with enhanced clustering capabilities. In addition, we suggest extensions of RGCL and LVQ that are characterized by the property of sustained exploration and significantly improve the performance of those algorithms, as indicated by experimental tests on well-known data sets.
Inertial-Force Feedback for the Treadport Locomotion Interface
Authors: Christensen Robert R. , Hollerbach John M. , Xu Yangming , Meek Sanford G.
Published: July 2002

The inertial force due to the acceleration of a locomotion interface is identified as a difference between virtual and real-world locomotion. To counter the inertial force, inertial-force feedback was implemented for the Treadport, a locomotion interface. A force controller was designed for a mechanical tether to apply the feedback force to the user. For the case of the user accelerating forward from rest, psychophysical ex periments showed that subjects preferred inertial-force feedback to a spring-feedback force proportional to position or to position control, where the force feedback maintained a force of zero on the subject.
The Room Effect: Metric Spatial Knowledge of Local and Separated Regions
Authors: Colle Herbert A. , Reid Gary B.
Published: July 2002

Navigating through real or virtual worlds requires a workable knowledge of the spatial layout. According to the landmark-route-survey model, metric spatial knowledge (survey knowledge) is acquired only following the acquisition of landmark and route knowledge. A dual mode model was proposed that assumes that survey knowledge may be quickly acquired for local regions. Research was conducted to understand how people rapidly acquire survey knowledge. Participants in three experiments briefly navigated on one floor of a virtual building, moving down hallways and performing tasks by using objects in rooms. Participants were later asked to answer from memory about the direction of objects by using pointing and map-drawing measures. A room effect was found for both measures; the angular positions of two objects in the same room were more accurately reported than those in different rooms. Accurate metric spatial information was available for objects in the same room, supporting an early acquisition assumption.
Human Factors Issues in Virtual Environments: A Review of the Literature
Authors: Stanney Kay M. , Mourant Ronald R. , Kennedy Robert S.
Published: July 2002

Virtual environments are envisioned as being systems that will enhance the communication between humans and computers. If virtual systems are to be effective and well received by their users, considerable human-factors research needs to be accomplished. This paper provides an overview of many of these human-factors issues, including human performance efficiency in virtual worlds (which is likely influenced by task characteristics, user characteristics, human sensory and motor physiology, multimodal interaction, and the potential need for new design metaphors); health and safety issues (of which cybersickness and deleterious physiological aftereffects may pose the most concern); and the social impact of the technology. The challenges each of these factors present to the effective design of virtual environments and systematic approaches to the resolution of each of these issues are discussed.
RNA Shape Space Topology
Authors: Cupal Jan , Kopp Stephan , Stadler Peter F.
Published: July 2002

The distinction between continuous and discontinuous transitions is a long-standing problem in the theory of evolution. Because continuity is a topological property, we present a formalism that treats the space of phenotypes as a (finite) topological space, with a topology that is derived from the probabilities with which one phenotype is accessible from another through changes at the genotypic level. The shape space of RNA secondary structures is used to illustrate this approach. We show that evolutionary trajectories are continuous if and only if they follow connected paths in phenotype space.
The Mixing Triangle: Correlation and Graphical Decision Support for LCA‐based Comparisons
Authors: Hofstetter Patrick , Braunschweig Arthur , Mettier Thomas , Müller‐Wenk Ruedi , Tietje Olaf
Published: July 2002

Recent developments within life‐cycle impact assessment (LCIA) allow direct modeling of changes to predefined safeguard subjects that represent the environment to be protected. These changes are often expressed in a few damage indicators and calculated for each product alternative to be compared. This article analyzes the correlation among damage indicators within one specific LCIA methodology, assesses the implications of such correlation for the use of weighting methods, and proposes a method for graphically displaying choices with respect to weighting.
Changing Patterns of Power in Cold War Politics: The Mysterious Case of Vladimír Komárek
Authors: Lukes Igor
Published: July 2002

The story of the arrest and imprisonment of Vladimír Komárek sheds valuable light on relations between Czechoslovakia and the United States in the 1950s and 1960s. Komárek, who had worked as an intelligence officer against the Czechoslovak Communist regime in the 1950s, was a U.S. citizen traveling to the Soviet Union on business when he was dramatically captured by the Czechoslovak authorities. Pressure from the U.S. government and private individuals, as well as conflicts between the Czechoslovak secret service and other, more liberal, elements in the Czechoslovak government, ultimately led to Komárek's release. Czechoslovakia's eventual willingness to cooperate in the Komárek case signaled a new approach to relations with the West, an approach that would have significant consequences during the Prague Spring of 1968.
The Changing Nature of Global Waste Management for the 21st Century: A Mixed Blessing?
Authors: O'Neill Kate
Published: July 2002

This article examines the impact of global and economic pressures on hazardous waste management practices during the 1980s and 1990s and into the twenty-first century. It charts out four sets of recent changes in these practices. These are: first, a shift in the basic regulatory problem, from one of a more local nature to the internationalization of waste management issues; second, changes in the structure of the waste disposal industry worldwide; third, changes in policies regarding hazardous waste in EU member states; and fourth, changes in waste management policies in emerging economies. The article analyzes these changes in the light of the growing involvement of the private sector in international environmental regulation, and of the complex and sometimes contradictory impacts of international regulations on domestic politics. It argues that neither a “race to the bottom” nor a “race to the top” hypothesis fully holds, but that changing public/private and domestic/international balances are a mixed blessing.
Sustainable Consumption Governance in a Globalizing World
Authors: Fuchs Doris A.
Published: July 2002

Our paper explores the implications of globalization for sustainable consump tion governance. It draws its central findings from a structured inquiry into the implications of globalization for the sustainability of household consumption. Our focus is on industrialized countries and the two consumption clusters food and mobility, which previous research has identified as priority areas for intervention. We find that for both food and mobility, globalization exerts a substantial influence on the sustainability of consumption through similar channels. Moreover, a significant part of this influence is exerted indirectly, i.e. affects prior determinants ofthe sustainability of household consumption rather than household consumption choices themselves. Based on our analysis, we suggest guidelines for the development of governance strategies in pursuit of sustain able consumption. In terms of general guidelines, we highlight the need for multilateral ifnot global strategies, as well as a comprehensive targeting of direct and indirect influences of globalization. Furthermore, we emphasize that governance strategies should pay particular attention to opportunities arising from the positive influences of globalization on the sustainability of consumption. In terms of specific guidelines, we argue that governance efforts should pay special attention to agricultural production conditions as well as transport options, as those pivotal determinants ofthe sustainability offood and mobility consumption are influenced by almost all ofthe elements of globalization. Likewise, we suggest that governance strategies need to address capital concentration, in particular, since the latter can be shown to influence almost all ofthe determinants of the sustainability of consumption.
EXCLUSIONS FROM THE CATECHUMENATE: CONTINUITY OR DISCONTINUITY WITH PAGAN CULT?
Authors: Dickie Matthew
Published: July 2002

This paper looks at the categories of person that two Christian documents, the Traditio apostolorum and Book 8 of the Constitutiones apostolorum, that belong respectively to the 3rd and later 4th centuries AD, propose be excluded from the catechumenate, apparently on the ground that the callings they follow make them morally-unfit. It asks whether that was the only reason for their exclusion and suggests that the prejudice from which such callings as performing on the stage and charioteering suffered in Roman society was also a factor. The paper then goes on to ask whether these exclusions from the catechumenate in their concern with moral fitness represent a radical new departure from anything to be found in pagan cult and whether we should continue to subscribe to the widely-held belief that pagan cult is not concerned with the moral state of the worshipper, but only with the punctilious performance of the ritual by persons not defiled by recent sexual contact or by the death of a close relative. It concludes that there is no discontinuity and that moral unworthiness could well be a source of concern in pagan cult.
Epicurus On Pleasure
Authors: Nikolsky Boris
Published: July 2002

The paper deals with the question of the attribution to Epicurus of the classification of pleasures into 'kinetic' and 'static'. This classification, usually regarded as authentic, confronts us with a number of problems and contradictions. Besides, it is only mentioned in a few sources that are not the most reliable. Following Gosling and Taylor, I believe that the authenticity of the classification may be called in question. The analysis of the ancient evidence concerning Epicurus' concept of pleasure is made according to the following principle: first, I consider the sources that do not mention the distinction between 'kinetic' and 'static' pleasures, and only then do I compare them with the other group of texts which comprises reports by Cicero, Diogenes Laertius and Athenaeus. From the former group of texts there emerges a concept of pleasure as a single and not twofold notion, while such terms as 'motion' and 'state' describe not two different phenomena but only two characteristics of the same phenomenon. On the other hand, the reports comprising the latter group appear to derive from one and the same doxographical tradition, and to be connected with the classification of ethical docrines put forward by the Middle Academy and known as the divisio Carneadea. In conclusion, I argue that the idea of Epicurus' classification of pleasures is based on a misinterpretation of Epicurus' concept in Academic doxography, which tended to contrapose it to doctrines of other schools, above all to the Cyrenaics' views.
THE RECONCEPTUALIZATION OF KINGSHIP IN DEUTERONOMY AND THE DEUTERONOMISTIC HISTORY'S TRANSFORMATION OF TORAH
Authors: Levinson Bernard
Published: July 2002

Because the royal ideology of ancient Israel was largely identical to that of the broader ancient Near East, the points of divergence are the more remarkable. In particular the legal corpus of Deuteronomy conceptualizes the king in a way that rejects all prevailing models of monarchic power, both Israelite and Near Eastern. Deuteronomy submits a utopian manifesto for a constitutional monarchy that sharply delimits the power of the king. This redefinition of royal authority takes place as part of a larger program (Deut. xvi 18-xviii 22) whereby the authors of Deuteronomy redefine the jurisdiction of each branch of public office (local and central judicial administration, kingship, priesthood, and prophecy). Each is subordinated, first, to the requirements of cultic centralization, and, second, to the textual authority of deuteronomic Torah. This utopian delimitation of royal power never passed from constitutional vision into historical implementation: it represented such a radical departure from precedent that the Deuteronomistic Historian, precisely while seeming to implement deuteronomic law, pointedly reversed the deuteronomic program and restored to the monarch all that Deuteronomy had withheld.
The osteology and relationships of Pipa aspera (Amphibia: Anura: Pipidae), with notes on its natural history in French Guiana
Authors: Trueb Linda , Massemin David
Published: July 2002

Recent field and laboratory observations on Pipa aspera from central French Guiana have yielded new information on the morphology, ecology, reproductive habits, and relationships of this poorly known pipid frog from northeastern South America. Morphologically, P.aspera is most similar to P.arrabali, from which it differs in details of its cranial and postcranial osteology. The snout of P.aspera is less depressed than that of P.arrabali and the eye is proportionally larger in P. aspera than in P. arrabali; in addition, P. aspera has wide nostrils that are more narrowly separated from one another than are those of P. arrabali. A phylogenetic analysis reveals P. carvalhoi to be the sister taxon to [P. aspera + [P. arrabali + [P. snethlageae + P. pipa]]]. Like P. arrabali, P. aspera produces relatively few, large young that undergo their complete development on the back of the female. Pipa aspera differs from its congeners in its preferred habitat of freshwater pools in flowing streams on the slopes of massifs of the Guyana Shield. De récents travaux menés en Guyane française sur l'amphibien anoure Pipa aspera (Pipidae) ont apporté des informations inédites sur la morphologie, l'écologie, le mode de reproduction et le comportement de cette espèce peu connue du Nord Est de l'Amérique du Sud. D'un point de vue morphologique, Pipa aspera est proche de P. arrabali duquel il se distingue toutefois par quelques détails de l'ostéologie crânienne et post-crânienne. De plus, chez P.aspera, le museau est moins déprimé et les yeux sont proportionnellement plus grands que chez P. arrabali. Les narines de Pipa aspera sont également plus larges et plus nettement séparées l'une de l'autre qu'elles ne le sont chez P.arrabali. Une analyse phylogénétique a révélé P.carvalhoi comme étant le taxon soeur de [P. aspera + [P. arrabali + [P. snethlageae + P. pipa]]]. Tout comme chez P. arrabali, les oeufs, pondus en petite quantité, se développent dans le dos de la femelle jusqu'à la métamorphose complète des têtards en jeunes grenouilles. Pipa aspera diffère également des autres Pipidés par son habitat particulier: des flaques alimentées par de l'eau vive et fraîche dans le lit de petites rivières dévalant le long de quelques reliefs marqués du plateau des Guyanes.
Burrowing ecology of the rare and elusive Louisiana pine snake, Pituophis ruthveni (Serpentes: Colubridae)
Authors: Himes John
Published: July 2002

The burrowing ecology of 12 adult and nine juvenile Louisiana pine snakes, Pituophis ruthveni, was studied during 1995-1997 in north-central Louisiana, U.S.A. Significantly more adult burrows connected to pocket gopher (Geomys breviceps) tunnels than did juvenile burrows, although a relatively high number of adult and juvenile snake burrows were blind-ended. Significantly more adult snake burrows were located in pine plantations and grasslands and significantly less were located in clearcuts than expected. Significantly more juvenile snake burrows were located in pine plantations than expected. Adult and juvenile snake burrows were located in areas that had relatively less leaf litter and canopy closure than expected. Excavation behavior by P. ruthveni was stereotyped and similar to excavation behavior by the bullsnake, Pituophis catenifer sayi and the northern pine snake, Pituophis melanoleucus melanoleucus.
SCENT MARKING IN MEADOW VOLES AND PRAIRIE VOLES: A TEST OF THREE HYPOTHESES
Authors: Ferkin M.H. , Mech S.G. , Paz-Y-Miño C.
Published: July 2002

Most terrestrial mammals deposit scent marks to communicate with conspecifics. We examined the scent marking behaviour of meadow voles and prairie voles, species with different mating systems and social organizations, to determine whether voles scent mark according to the 'targeting' response, the 'avoidance' response, or the 'shotgun' response. The targeting response occurs when the second scent donor deposits more of its scent marks in an area marked by the first scent donor than in an unscented area. The avoidance response occurs when the second scent donor deposits more of its scent marks in an unscented area than in an area marked by the first scent donor. The shotgun response occurs when the second scent donor deposits a similar number of its scent marks in an area containing scent marks of a conspecific and in an area containing no conspecific scent marks. We allowed voles simultaneous access to an arena containing two arms: one of the arms was scented by a conspecific and the other arm was unscented. We recorded the number of marks deposited by the voles in each arm and the amount of time they spent investigating marks deposited previously in the scented arm. Our data provide no support for the avoidance response, but provide support for the shotgun response and the target response. Species and sex differences in the scent marking behaviours of voles when they encounter the scent marks of conspecifics are discussed within the framework that scent marking responses depend on the voles' social organization and mating system, and that these responses may reflect the tactics males and females use to attract mates and compete with same-sex conspecifics.
A COMMENT ON A RECENT PHYLOGENETIC ANALYSIS OF CERTAIN ORDERS OF THE BRANCHIOPOD CRUSTACEA
Authors: Fryer Geoffrey
Published: July 2002

A recent phylogenetic analysis of certain branchiopod crustaceans has many defects. It uses many characters of no phylogenetic significance, others whose state is wrongly assessed, and others that are inapplicable to the organisms concerned. Based as it is on such imperfect information, some of its conclusions are unacceptable, though, ironically, some correct associations are made on the basis of incorrect facts. Une analyse phylogenetique recente de certains crustaces branchiopodes presente beaucoup de defauts. Elle utilise beaucoup de caracteres sans signification phylogenetique, d'autres dont l'etat est mal evalue, et d'autres encore qui ne sont pas applicables aux organismes concernes. Fondees sur une telle information imparfaite, certaines de ses conclusions sont inacceptables, encore que, ironiquement, plusieurs associations soient correctes, bien que fondees sur des faits incorrects.
Redescription of the highly specialized aquatic †Tigrivia and the classification of the Mesozoic †Coptoclavidae (Coleoptera, Adephaga, Dytiscoidea)
Authors: BAO LIANG , BEUTEL ROLF GEORG , NIU KECHENG , BAO TONG
Published: February 2025

†Tigrivia baii, a highly specialized aquatic beetle assigned to the adephagan †Coptoclavidae, is redescribed and documented in detail. The observed morphological features are discussed with respect to function, phylogenetic significance, and the current classification of the Mesozoic family. Cladistic analyses indicate that †Tigrivia is the sister taxon of †Coptoclava. Both may be closely related with †Daohugounectes, but this was not confirmed by the analyses. †Tigrivia is a highly specialized genus, more advanced than the closely related †Coptoclava, showing a range of features suggesting evolutionary parallels with Gyrinidae, i.e. long raptorial forelegs, a very small prosternal process, an unusually large mesoventrite without hexagonal groove, apically truncated elytra, and exposed appendices of abdominal segment VIII. However, a detailed assessment of these features and the phylogenetic analysis revealed that these derived characteristics have evolved independently in †Tigrivia and whirligig beetles. †Tigrivia and other beetles in †Coptoclavidae were likely facultative surface hunters, but less specialized than Gyrinidae, which can swim rapidly on the surface film with paddle-like short middle and hind legs. In any case †Tigrivia and †Coptoclava were active predators, likely preying on small fishes and amphibian larvae. †Coptoclavidae is not monophyletic, and the same is probably true for most of the subfamilies, especially †Necronectinae (= †Timarchopsinae). While many coptoclavid taxa display subdivided compound eyes with an upper and lower subunit, this feature is not a synapomorphy since it is not found in all genera. Groups with metacoxae of a haliplid or trachypachid type, with the mesal walls not fused and with large posterior plates, apparently do not belong to Dytiscoidea, and should be removed from †Coptoclavidae. The rest of the family, characterized by extensively fused mesal metacoxal walls and largely reduced coxal plates belong to a clade comprising all dytiscoid families except for Noteridae and Meruidae.
A new genus of Pachybrachini from Bolivia (Coleoptera: Chrysomelidae: Cryptocephalinae)
Authors: SASSI DAVIDE
Published: February 2025

Griburella gen. nov. is described from Central Bolivia, with Griburella sanctaecrucis sp. nov. as the sole species belonging to it. The new taxon superficially resembles certain forms of the polymorphic (and likely polyphyletic) genus Griburius Haldeman, 1849 but no species of the latter, nor any Pachybrachini known up to now, has appendiculate claws, as observed in Griburella gen. nov. The latter also differs from Griburius in its narrow and elongated prosternal process, the absence of the typical thickening of the forelegs in males, and the presence of extremely dense and regularly spaced punctation on both the elytra and the pronotum. Notably, no indication of true elytral striae formation is observed on the elytra.
A southward range extension of the rockfish, Sebastes ventricosus (Scorpaeniformes: Scorpaenidae: Sebastinae) to Matsu Islands, Taiwan
Authors: SU YO , YANG TSUNGYU , LIN CHIENHSIANG
Published: February 2025

The rockfish species, Sebastes ventricosus Temminck & Schlegel, 1843, previously documented in the southern Korean Peninsula and Japan, typically at latitudes above 32° N, is recorded for the first time in Matsu Islands, Lienchiang County, Taiwan (ca. 26° N). A detailed description of the single specimen, along with its sagittal otolith, is provided and compared with data from other specimens collected from the northwestern Pacific Ocean. This discovery marks the second record of the genus Sebastes in Taiwan’s EEZ and represents the fourth documented case of southward range extension for cold-water fishes to Taiwan. We suggest that further investigation is needed to understand the mechanism behind this southward movement, as it does not align with the typical warming trend that facilitates northward expansion.
Hooked on Livestreaming: What Drives Customer Repurchase Intention in E-Commerce?
Authors: Phan Linh-Gia Ngoc , Tri Dang Quan , Dang Son-Hoang , Nguyen Luan-Thanh
Published: February 2025

This research investigates the psychological mechanisms underlying customers repurchase behavioural intention on e-commerce livestreaming, framed by the theory of customer inspiration (CIT) and social cognitive theory (SCT). Based on SCT and CIT, the study identifies factors influencing customer inspiration on e-commerce livestreaming from three key perspectives: technical environment (i.e., interactivity), personal factors (i.e., perceived value, self-efficacy), and customer experience (i.e., hedonic outcome expectation, utilitarian outcome expectation), which in turn drive repurchase behavioural intention. A structural equation model examined repurchase behavioural intention on e-commerce livestreaming from a customer inspiration standpoint. The model was tested using Partial Least Squares Structural Equation Modeling (PLS-SEM) based on data collected from an online survey of 158 participants. The research found that perceived value and customer experience (i.e., hedonic outcome expectation, utilitarian outcome expectation) favourably affect customers’ ‘inspired-by’ on e-commerce livestreaming. The ‘inspired-to’ stage follows, causing repurchase behavioural intention. This study shows a connection between repurchase behavioural intention and customer inspiration, offering a novel psychological perspective for understanding repurchase behavioural intention. Furthermore, it examines the antecedents of customer inspiration via the lens of SCT, offering initial evidence linking customer inspiration to consumer behaviour.
Evaluation of risk factors associated with acute kidney injury in a level IV regional NICU
Authors: Hartman KL , Geraci E , Spencer J , Kukla M , Acquisto NM , Hutchinson DJ
Published: February 2025

Background

Intervening on neonates at risk for developing acute kidney injury (AKI) improves safety and clinical outcomes. This study sought to evaluate risk factors associated with AKI in a level IV neonatal intensive care unit (NICU).

Methods

Single-center, case-control study of patients with corrected gestational age (GA) ≤44 weeks from 2018 to 2022. Cases were those that developed AKI after day 4 of life. Controls were the next neonate admitted to the same NICU team that met inclusion criteria but did not develop AKI. Neonatal and maternal factors, nephrotoxic medication administration, and procedures were analyzed to identify risk factors associated with AKI using univariate and multivariate analyses.

Results

A total of 94 patients were included: 47 cases and 47 controls. GA <27 weeks, birth weight <1500 grams, low APGAR score, intubation at birth, bronchopulmonary dysplasia (BPD), patent ductus arteriosus (PDA), necrotizing enterocolitis (NEC), and sepsis were associated with AKI on univariate analysis. Most cases (89.4%) had >4 risk factors, and this was associated with a 13.1-fold increase in the odds of developing AKI. Multivariate analysis identified GA <27 weeks (OR 7.7, 95% CI 1.7–34.4), vasopressor and/or inotrope administration (OR 4.4, 95% CI 1.2–23.8), and diagnosis of PDA (OR 6.9, 95% CI 1.5–31.3) as independent predictors of AKI.

Conclusions

Risk factors associated with AKI were identified, and a 13.1-fold increase in AKI was found when >4 risk factors were present. This information may be used to expand renal acuity surveillance programs focusing on high-risk medication evaluation, demographic, and clinical factors.
An empirical Scherrer equation for weakly swelling mixed-layer minerals, especially illite-smectite
Authors: Jaboyedoff M. , Kübler B. , Thélin Ph.
Published: July 2002

The Scherrer equation links the measured width of an X-ray diffraction peak (Scherrer width, SW) to the number of stacked cells (N) in the direction normal to the diffracting planes. The formula is only valid for one d-value occurring in the coherently diffracting domain. This equation can be modified for weakly swelling mixed-layer minerals. This assumes that the peak broadening caused by the mixed-layering is proportional to the amount of swelling component (S) and that the effects of size and mixed-layering are additive.

If two SW can be measured on XRD patterns from samples treated in two different ways (such as air dried or glycolated), N and S can be determined. This equation is applicable to illite-smectite mixed-layer minerals with high illitic content. The results are most accurate for N>30. The use of Scherrer's equation is discussed.
Nano-scale microstructure of Fe3+-, OH−-bearing crystalline inclusions in experimentally oxidized olivine from a mantle nodule
Authors: Khisina N. R. , Langer K. , Andrut M. , Ukhanov A. V. , Wirth R.
Published: July 2002

An olivine grain from peridotite nodule 9206 (Udachnaya kimberlite) was heated in air at 700°C for 9 h. It was investigated by EMPA, by IR and UV spectroscopy and by TEM. The TEM examination reveals hexagon-like inclusions up to several hundred nm in size with a core and rim structure. The AEM data show that the inclusions contain only Mg, Fe and Si as cations. The rims have almost the same composition as the olivine matrix whereas the cores are enriched in iron and depleted in Mg. Electron diffraction data, SAED and CBED, indicate that the rims are composed of a ‘secondary’ olivine while the cores are composed of coexisting feroxyhite FeOOH, bernalite Fe(OH)3 and β-cristobalite SiO2. The presence of nm-sized inclusions in minerals is expected to influence the interpretation of spectroscopic results if spectroscopy is carried out without knowledge of the microstructure.

It is speculated that the complex microstructure of the inclusions is a result of a solid state transformation of a precursor phase, probably a hydrous magnesian silicate, during the experimental heating and oxidation.
Leucite-pollucite structure-type variability and the structure of a synthetic end-member calcium wairakite (CaAl2Si4O12·2H2O)
Authors: Henderson C. M. B. , Bell A. M. T. , Kohn S. C. , Page C. S.
Published: July 2002

The structure of a synthetic end-member wairakite (CaAl2Si4O12·2H2O) has been determined using Rietveld analysis of high-resolution, synchrotron X-ray powder diffraction data, and 29Si and 27Al magic angle spinning nuclear magnetic resonance spectroscopy. The framework in the synthetic sample is more disordered than that in natural wairakite. Ca is distributed over the cavity cation sites M2, M12A, M12B in the approximate proportions 0.8:0.1:0.1, respectively, with M11 being vacant. 29Si MAS NMR data are consistent with about 80% of the Si occupying tetrahedral T11 and T12 sites linked to two Al atoms [Q4(2Al) silicons]. Tetrahedral and cavity cation site disorder are coupled so that Al mainly occupies T2 sites, with Ca in M12A and M12B being balanced by Al in T12A and T12B; T11A and T11B sites appear to only contain Si, in agreement with the M11 site being vacant. The crystal chemistries of the wide range of stoichiometries which crystallize with the leucite/pollucite structure-type are also reviewed, with particular attention being paid to the tetrahedral ordering configurations present in these phases, and the implications to crystallographic phase transitions.
The composition and structure of jeanbandyite and natanite
Authors: Betterton J. , Green D. I. , Jewson C. , Spratt J. , Tandy P.
Published: July 2002

The rare iron-tin hydroxide minerals natanite and jeanbandyite occur as small pseudo-octahedral crystals in high-temperature Sn-Cu-As veins at Penberthy Croft Mine and Hingston Downs Quarry, Cornwall. The lattice parameters for jeanbandyite and natanite are reported and compared to previously calculated values. The chemical composition of jeanbandyite is discussed and a significant proportion of divalent Fe and Mn is shown to be present.
Model for a factor IX activation complex on blood platelets: dimeric conformation of factor XIa is essential
Authors: Gailani David , Ho David , Sun Mao-Fu , Cheng Qiufang , Walsh Peter N.
Published: July 2002

Human coagulation factor XI (FXI) is a plasma serine protease composed of 2 identical 80-kd polypeptides connected by a disulfide bond. This dimeric structure is unique among blood coagulation enzymes. The hypothesis was tested that dimeric conformation is required for normal FXI function by generating a monomeric version of FXI (FXI/PKA4) and comparing it to wild-type FXI in assays requiring factor IX activation by activated FXI (FXIa). FXI/PKA4 was made by replacing the FXI A4 domain with the A4 domain from prekallikrein (PK). A dimeric version of FXI/PKA4 (FXI/PKA4-Gly326) was prepared as a control. Activated FXI/PKA4 and FXI/PKA4-Gly326 activate factor IX with kinetic parameters similar to those of FXIa. In kaolin-triggered plasma clotting assays containing purified phospholipid, FXI/PKA4 and FXI/PKA4-Gly326 have coagulant activity similar to FXI. The surface of activated platelets is likely to be a physiologic site for reactions involving FXI/FXIa. In competition binding assays FXI/PKA4, FXI/PKA4-Gly326, and FXI have similar affinities for activated platelets (Ki = 12-16 nM). In clotting assays in which phospholipid is replaced by activated platelets, the dimeric proteins FXI and FXI/PKA4-Gly326 promote coagulation similarly; however, monomeric FXI/PKA4 has greatly reduced activity. Western immunoblot analysis confirmed that activated monomeric FXI/PKA4 activates factor IX poorly in the presence of activated platelets. These findings demonstrate the importance of the dimeric state to FXI activity and suggest a novel model for factor IX activation in which FXIa binds to activated platelets by one chain of the dimer, while binding to factor IX through the other.
Umbilical cord blood cells capable of engrafting in primary, secondary, and tertiary xenogeneic hosts are preserved after ex vivo culture in a noncontact system
Authors: Lewis Ian D. , Almeida-Porada Graca , Du Jingbo , Lemischka Ihor R. , Moore Kateri A. , Zanjani Esmail D. , Verfaillie Catherine M.
Published: July 2002

This report describes stroma-based and stroma-free cultures that maintain long-term engrafting hematopoietic cells for at least 14 days ex vivo. Umbilical cord blood (UCB) CD34+ cells were cultured in transwells above AFT024 feeders with fetal-liver-tyrosine-kinase (FL) + stem cell factor (SCF) + interleukin 7 (IL-7), or FL + thrombopoietin (Tpo). CD34+ progeny were transplanted into nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice or preimmune fetal sheep. SCID repopulating cells (SRC) with multilineage differentiation potential were maintained in FL-SCF-IL-7 or FL-Tpo containing cultures for up to 28 days. Marrow from mice highly engrafted with uncultured or expanded cells induced multilineage human hematopoiesis in 50% of secondary but not tertiary recipients. Day 7 expanded cells engrafted primary, secondary, and tertiary fetal sheep. Day 14 expanded cells, although engrafting primary and to a lesser degree secondary fetal sheep, failed to engraft tertiary recipients. SRC that can be transferred to secondary recipients were maintained for at least 14 days in medium containing glycosaminoglycans and cytokines found in stromal supernatants. This is the first demonstration that ex vivo culture in stroma-noncontact and stroma-free cultures maintains “long-term” engrafting cells, defined by their capacity to engraft secondary or tertiary hosts.
Activation of the formyl peptide receptor by the HIV-derived peptide T-20 suppresses interleukin-12 p70 production by human monocytes
Authors: Braun Michael C. , Wang Ji Ming , Lahey Edward , Rabin Ronald L. , Kelsall Brian L.
Published: July 2002

It has been proposed that in the early stages of human immunodeficiency (HIV) infection, before the loss of CD4+ T cells, inhibition of IL-12 production from host antigen-presenting cells plays a critical role in the suppression of T-helper cell type 1 responses. Activation of the Gi-protein–coupled high-affinity N-formyl peptide receptor by f-met-leu-phe and HIV-derived peptide T-20–suppressed IL-12 p70 production from human monocytes in response to both T-cell–dependent and T-cell–independent stimulation are reported. Activation of the low-affinity N-formyl peptide receptor by the HIV-derived F-peptide suppressed IL-12 production more modestly. This suppression was pertussis toxin sensitive and was selective for IL-12; the production of IL-10, transforming growth factor-β, and tumor necrosis factor-α was unaltered. The production of IL-12 p70 by dendritic cells was unaffected by these peptides despite functional expression of the high-affinity fMLP receptor. These findings provide a potential direct mechanism for HIV-mediated suppression of IL-12 production and suggest a broader role for G-protein–coupled receptors in the regulation of innate immune responses.
Polyethylene glycol–coated red blood cells fail to bind glycophorin A–specific antibodies and are impervious to invasion by the Plasmodium falciparum malaria parasite
Authors: Blackall Douglas P. , Armstrong Jonathan K. , Meiselman Herbert J. , Fisher Timothy C.
Published: July 2002

This study was designed to assess the binding of glycophorin A–specific antibodies to polyethylene glycol (PEG)-modified red blood cells (RBCs) and evaluate their resistance to invasion byPlasmodium falciparum malaria parasites. RBCs were conjugated with a range of concentrations (0.05 to 7.5 mM) of activated PEG derivatives of either 3.35 or 18.5 kd molecular mass. The binding of glycophorin A–specific antibodies was assessed by hemagglutination and flow cytometry. PEG-modified RBCs were assessed for their ability to form rosettes around Chinese hamster ovary (CHO) cells transiently expressing the glycophorin A binding domain of EBA-175, a P falciparum ligand crucial to RBC invasion. PEG-RBCs were also tested for their ability to be invaded by the malaria parasite. RBCs coated with 3.35 and 18.5 kd PEG demonstrated a dose-dependent inhibition of glycophorin A–specific antibody binding, CHO cell rosetting, and P falciparum invasion. These results indicate that glycophorin A epitopes responsible for antibody and parasite binding are concealed by PEG coating, rendering these cells resistant to P falciparum invasion. These studies confirm the effectiveness of PEG modification for masking RBC-surface glycoproteins. This may provide a means to prevent alloimmunization in the setting of RBC transfusion and suggests a novel method to enhance the effectiveness of exchange transfusion for the treatment of cerebral malaria.
Induction of cytotoxic T lymphocyte and antibody responses to enhanced green fluorescent protein following transplantation of transduced CD34+ hematopoietic cells
Authors: Rosenzweig Michael , Connole Michelle , Glickman Rhona , Yue Soon-Pak Shinji , Noren Bradley , DeMaria MaryAnn , Johnson R. Paul
Published: July 2002

Genetic modification of hematopoietic stem cells often results in the expression of foreign proteins in pluripotent progenitor cells and their progeny. However, the potential for products of foreign genes introduced into hematopoietic stem cells to induce host immune responses is not well understood. Gene marking and induction of immune responses to enhanced green fluorescent protein (eGFP) were examined in rhesus macaques that underwent nonmyeloablative irradiation followed by infusions of CD34+ bone marrow cells transduced with a retroviral vector expressing eGFP. CD34+ cells were obtained from untreated animals or from animals treated with recombinant human granulocyte colony-stimulating factor (G-CSF) alone or G-CSF and recombinant human stem cell factor. Levels of eGFP-expressing cells detected by flow cytometry peaked at 0.1% to 0.5% of all leukocytes 1 to 4 weeks after transplantation. Proviral DNA was detected in 0% to 17% of bone marrow–derived colony-forming units at periods of 5 to 18 weeks after transplantation. However, 5 of 6 animals studied demonstrated a vigorous eGFP-specific cytotoxic T lymphocyte (CTL) response that was associated with a loss of genetically modified cells in peripheral blood, as demonstrated by both flow cytometry and polymerase chain reaction. The eGFP-specific CTL responses were MHC-restricted, mediated by CD8+lymphocytes, and directed against multiple epitopes. eGFP-specific CTLs were able to efficiently lyse autologous CD34+ cells expressing eGFP. Antibody responses to eGFP were detected in 3 of 6 animals. These data document the potential for foreign proteins expressed in CD34+ hematopoietic cells and their progeny to induce antibody and CTL responses in the setting of a clinically applicable transplantation protocol.
Immunosuppressive properties of CD95L-transduced “killer” hybrids created by fusing donor- and recipient-derived dendritic cells
Authors: Matsue Hiroyuki , Matsue Keiko , Kusuhara Masahiro , Kumamoto Tadashi , Okumura Ko , Yagita Hideo , Takashima Akira
Published: July 2002

Allogeneic immune responses, which are initiated by dendritic cells (DCs) of both donor and host origins, remain a major obstacle in organ transplantation. Presentation of intact major histocompatibility complex (MHC) molecules by allogeneic DCs and allogeneic peptides by syngeneic DCs leads to complex allogeneic immune responses. This study reports a novel strategy designed to suppress both pathways. A stable DC line XS106 (A/J mouse origin) was transfected with CD95L cDNA and fused with splenic DCs purified from allogeneic BALB/c mice. The resulting “killer” DC-DC hybrids: (1) expressed CD95L and MHC class I and class II molecules of both A/J and BALB/c origins, while maintaining otherwise characteristic surface phenotypes of mature DCs; (2) inhibited MHC class I– and class II–restricted mixed leukocyte reactions between the parental strains by triggering apoptosis of alloreactive T cells; and (3) abolished delayed-type hypersensitivity responses of A/J (and BALB/c) mice to BALB/c-associated (and A/J-associated) alloantigens when injected intravenously into A/J (and BALB/c) mice. The onset of graft-versus-host disease in (BALB/c × A/J) F1 hosts receiving A/J-derived hematopoietic cell transplantation was suppressed significantly (P < .001) by killer DC-DC hybrid treatment. These results form both technical and conceptual frameworks for clinical applications of CD95L-transduced killer hybrids created between donor DCs and recipient DCs in the prevention of allogeneic immune responses following organ transplantation.
Molecular tracking of leukemogenesis in a triplet pregnancy
Authors: Maia Ana Teresa , Ford Anthony M. , Jalali G. Reza , Harrison Christine J. , Taylor G. Malcolm , Eden Osborn B. , Greaves Mel F.
Published: July 2002

The occurrence of childhood acute lymphoblastic leukemia (ALL) in 2 of 3 triplets provided a unique opportunity for the investigation of leukemogenesis and the natural history of ALL. The 2 leukemic triplets were monozygotic twins and shared an identical, acquiredTEL-AML1 genomic fusion sequence indicative of a single-cell origin in utero in one fetus followed by dissemination of clonal progeny to the comonozygotic twin by intraplacental transfer. In accord with this interpretation, clonotypic TEL-AML1 fusion sequences could be amplified from the archived neonatal blood spots of the leukemic twins. The blood spot of the third, healthy, dizygotic triplet was also fusion gene positive in a single segment, though at age 3 years, his blood was found negative by sensitive polymerase chain reaction (PCR) screening for the genomic sequence and by reverse transcription–PCR. Leukemic cells in both twins had, in addition toTEL-AML1 fusion, a deletion of the normal, nonrearrangedTEL allele. However, this genetic change was found by fluorescence in situ hybridization to be subclonal in both twins. Furthermore, mapping of the genomic boundaries of TELdeletions using microsatellite markers indicated that they were individually distinct in the twins and therefore must have arisen as independent and secondary events, probably after birth. These data support a multihit temporal model for the pathogenesis of the common form of childhood leukemia.
Chemoattractants MDC and TARC are secreted by malignant B-cell precursors following CD40 ligation and support the migration of leukemia-specific T cells
Authors: Ghia Paolo , Transidico Pietro , Veiga J. Pedro , Schaniel Christoph , Sallusto Federica , Matsushima Kouji , Sallan Stephen E. , Rolink Antonius G. , Mantovani Alberto , Nadler Lee M. , Cardoso Angelo A.
Published: July 2002

The use of tumor cells as vaccines in cancer immunotherapy is critically dependent on their capacity to initiate and amplify tumor-specific immunity. Optimal responses may require the modification of the tumor cells not only to increase their immunogenicity but also to improve their ability to recruit effector cells to the tumor sites or sites of tumor antigen exposure. It has been reported that CD40 cross-linking of acute lymphoblastic leukemia (ALL) cells significantly increases their immunogenicity and allows the generation and expansion of autologous antileukemia cytotoxic T lymphocytes. This study demonstrates that the CD40 ligation of these tumor cells also induces the secretion of the CC-chemokines MDC and TARC. Supernatants from malignant cells cultured in the presence of sCD40L promote the migration of activated T cells that express CCR4, the common specific receptor for MDC and TARC. More importantly, the supernatants from CD40-stimulated tumor cells also support the transendothelial migration of autologous CCR4+ antileukemia T cells. Therefore, the results demonstrate that the delivery to leukemia cells of a single physiologic signal, that is, CD40 cross-linking, simultaneously improves tumor cell immunogenicity and induces potent chemoattraction for T cells.
Characterization of thymus-seeding precursor cells from mouse bone marrow
Authors: Mori Shinichiro , Shortman Ken , Wu Li
Published: July 2002

The nature of the cells that seed the thymus of an irradiated recipient after intravenous (IV) transfer of bone marrow (BM) cells was investigated using 2 approaches. First, direct entry of a small number of donor BM cells into the thymus was tracked using a Ly-5 marker. Second, secondary IV transfer of the seeded thymus cells into a secondary recipient was used as an assay for precursor activity. A range of cell types was found to enter the recipient thymus initially, including B-lineage cells and myeloid cells, but T precursors were undetectable by flow cytometry over the first few days. Although all cells initially entering the thymus proliferated, no sustained thymus reconstitution was seen until day 4, when recognizable T-lineage precursors began to appear. The secondary transfer assays revealed the presence of lymphoid precursors in the recipient thymus, including T, NKT, NK, and B precursor activity, with a notable early burst of B-lineage generative capacity. There was no evidence of sustained myeloid precursor or multipotent stem cell activity, even though these were seen if BM cells were injected directly into the recipient thymus rather than introduced into the bloodstream. It is concluded that even though many cell types may initially enter an irradiated thymus, the thymus acts as a sieve, allowing lymphoid precursors, but not multipotent stem cells, to seed the environmental niches that permit selected precursor cell development and thymus reconstitution.