bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental and spatial controls of palm (Arecaceae) species richness across the Americas
Authors: Bjorholm Stine , Svenning Jens‐Christian , Skov Flemming , Balslev Henrik
Published: August 2005

Aim  To determine the main factors that control the distribution of palm species richness across the Americas, to understand the relative importance of climatic and other environmental factors vs. spatial variables (as substitutes for non‐environmental factors such as history), and to evaluate how robust the patterns found are to changes in spatial scale.

Location  Tropical and subtropical America (34°N−34°S; 33°W−120°W).

Methods  We provide a GIS‐based analysis of spatial variation in species richness at 10 grain sizes (1°−10° square grid cells). We use multiple regressions and variation partitioning to test patterns of species richness in relation to five environmental descriptors [mean annual temperature (°C), mean annual precipitation (mm year−1), number of wet days year−1, topographical range (maximum–minimum elevation), number of vegetation types] and nine spatial variables (the terms of a cubic trend‐surface polynomial).

Results  We observe peaks in palm species richness in southern Mesoamerica, the Chocó area, western and eastern Amazon basin, and east Andean slopes, and a strong latitudinal richness gradient even within the tropical zone. Pure environmental and pure spatial variation components are of equal magnitude through all spatial scales analysed. Water‐related variables such as annual rainfall and number of wet days are the main richness predictors. Spatial variables, notably latitude squared are also important, whereas temperature‐ and habitat‐related variables are relatively unimportant.

Main conclusions  Our analysis suggests that in the Americas, palm species richness at spatial scales from 1° to 10° is most strongly controlled by water availability, although unknown broad‐scale factors, perhaps soil, historical processes or geometric constraints, are also important.
Bioclimatic modelling using Gaussian mixture distributions and multiscale segmentation
Authors: Gavin Daniel G. , Hu Feng Sheng
Published: August 2005

Aim To introduce Gaussian mixture distributions and sequential maximum a posteriori image segmentation (GM‐SMAP) as a model that predicts species ranges from mapped climatic variables, and to compare its predictive capacity with two commonly used bioclimatic models: regression tree analysis (RTA) and smoothed response surfaces (SRS).

Location North‐west North America.

Methods We compared models for their ability to predict the distributional range of western hemlock (Tsuga heterophylla). We calculated and projected nine climatic and water‐balance variables to a 2‐km grid up to 140 km from theT. heterophyllarange. Models were trained using the five variables selected by RTA, as well as subsets of three variables. Goodness of fit was assessed using models trained and tested on the entire study area. Predictive capacity was assessed using 100 cross‐validation tests, each trained on a randomly sampled 1% of the study area and tested on the complement of the study area.

Results Models using all five variables were significantly better than three‐variable models. Model fit was greatest for SRS. GM‐SMAP misclassified slightly more area and RTA misclassified almost twice the area compared to SRS. However, cross‐ validation showed that the predictive capacity was clearly greatest for GM‐SMAP and lowest for SRS, indicating that GM‐SMAP makes more accurate predictions from sparse data.

Main conclusions GM distributions prevent overfitting using an information‐theoretic approach, and the SMAP algorithm minimizes the spatial extent of the largest misclassified area using a multiscale method. These properties, useful for image classification, also aid their strong predictive capacity as a bioclimatic model. SRS overfit the data, lowering its predictive capacity, and RTA failed to capture details of interactions among variables, yielding a poor fit. These results demonstrate the strong potential of GM‐SMAP as a bioclimatic model.
The Voluntary Redundancy Option: Carrot or Stick?
Authors: Clarke Marilyn
Published: August 2005

Voluntary redundancy is a relatively new form of retrenchment that has become a popular means of reducing workforce numbers in downsizing organizations. Voluntary redundancy involves the offer of a financial incentive to encourage employees to ‘volunteer’ for redundancy. Using the findings of a small study of individuals who had taken voluntary redundancy, this paper explores the voluntary nature of voluntary redundancy and suggests that both organizational change and the financial incentive are contributors to the redundancy decision. From an organizational perspective voluntary redundancy does appear to smooth the downsizing process but at the same time tends to mask underlying issues of morale and commitment.
An Exact Distribution-Free Test Comparing Two Multivariate Distributions based on Adjacency
Authors: Rosenbaum Paul R.
Published: August 2005

A new test is proposed comparing two multivariate distributions by using distances between observations. Unlike earlier tests using interpoint distances, the new test statistic has a known exact distribution and is exactly distribution free. The interpoint distances are used to construct an optimal non-bipartite matching, i.e. a matching of the observations into disjoint pairs to minimize the total distance within pairs. The cross-match statistic is the number of pairs containing one observation from the first distribution and one from the second. Distributions that are very different will exhibit few cross-matches. When comparing two discrete distributions with finite support, the test is consistent against all alternatives. The test is applied to a study of brain activation measured by functional magnetic resonance imaging during two linguistic tasks, comparing brains that are impaired by arteriovenous abnormalities with normal controls. A second exact distribution-free test is also discussed: it ranks the pairs and sums the ranks of the cross-matched pairs.
On Nonparametric Maximum Likelihood Estimation with Interval Censoring and Left Truncation
Authors: Hudgens Michael G.
Published: August 2005

A graph theoretical approach is employed to describe the support set of the nonparametric maximum likelihood estimator for the cumulative distribution function given interval-censored and left-truncated data. A necessary and sufficient condition for the existence of a nonparametric maximum likelihood estimator is then derived. Two previously analysed data sets are revisited.
A Note on Non-Negative Continuous Time Processes
Authors: Tsai Henghsiu , Chan K. S.
Published: August 2005

Recently there has been much work on developing models that are suitable for analysing the volatility of a continuous time process. One general approach is to define a volatility process as the convolution of a kernel with a non-decreasing Lévy process, which is non-negative if the kernel is non-negative. Within the framework of time continuous autoregressive moving average (CARMA) processes, we derive a necessary and sufficient condition for the kernel to be non-negative. This condition is in terms of the Laplace transform of the CARMA kernel, which has a simple form. We discuss some useful consequences of this result and delineate the parametric region of stationarity and non-negative kernel for some lower order CARMA models.
Reshaping the State: Administrative Reform and New Public Management in France
Authors: COLE ALISTAIR , JONES GLYN
Published: August 2005

This essay examines the administrative reform process in France since the late 1980s. The key reforms undertaken during this period have sought to delegate greater managerial autonomy to the ministerial field‐service level. We undertook semistructured interviews with officials in the field services of three French ministries (Education, Agriculture, and Infrastructure) in the Champagne‐Ardennes region, as well as with members of the wider policy communities. The capacity of the field services to adopt a proactive approach to management reform depended on five key variables: internal organizational dynamics; the attitude of the central services to mesolevel autonomy; the degree of institutional receptivity to change; the type of service delivery, and the extent of penetration in local networks. The Infrastructure Ministry was more receptive to management change than either Education or (especially) Agriculture, a receptivity that reflects the institutional diversity of the French administrative system, and that supports new institutionalist arguments. The essay rejects straightforward convergence to the New Policy Management norm. Changes in public management norms require either endogenous discursive shifts or else need to be interpreted in terms of domestic registers that are acceptable or understandable to those charged with implementing reform.
The Institutionalization of Private Governance: How Business and Nonprofit Organizations Agree on Transnational Rules
Authors: PATTBERG PHILIPP
Published: August 2005

This article assesses the recent trend of cooperation among antagonistic private actors that results in the creation and implementation of issue‐specific transnational norms and rules and the subsequent shift from public to private forms of governance. Many political scientists agree that authority also exists outside of formal political structures. Private actors increasingly begin to make their own rules and standards that acquire authority beyond the international system. This observation is often referred to as private transnational governance as opposed to public or international governance. Although the concept of private governance gains prominence in academic debates, it is not clear how private governance on the global scale is constructed and maintained or what specific or general conditions are necessary for private governance to emerge. Based on the review of common theoretical propositions, this article develops an integrated model along which the necessary conditions for the emergence of private governance can be assessed and understood. As most research has hitherto focused on institutionalized cooperation between business actors (self‐regulation), this article takes a closer look at those transnational systems of rule that result out of the enhanced cooperation between profit and nonprofit actors (coregulation).
Rules that Many Use: Standards and Global Regulation
Authors: KERWER DIETER
Published: August 2005

Global regulation increasingly relies on alternatives to legal rules, variously termed “soft law,”“best‐practice rules,” or “standards.” Such voluntary best‐practice rules can be highly effective. Standards influence users by virtue of the expertise on which they are based and because of their enforcement by public and private actors. Standards globally proliferate because they are more compatible with regulatory autonomy of states than binding directives. When global standards are effective, the question of how to subject them to democratic control often arises. The prospects for holding global standard setters accountable largely depend on how decisions on standards are made. These insights are illustrated by examples of the global regulation of financial markets. The preliminary evidence suggests that standards need to be taken more seriously by students of global regulation.
Negotiating International Food Standards: The World Trade Organization's Impact on the Codex Alimentarius Commission
Authors: VEGGELAND FRODE , BORGEN SVEIN OLE
Published: August 2005

The article presents an empirical account of how the role, position, and perception of the intergovernmental food standardization body, Codex Alimentarius Commission, has changed after being referred to by the World Trade Organization (WTO) as the “central reference point for the elaboration of international food standards.” Both the Sanitary and Phytosanitary Measures Agreement and the Technical Barriers to Trade Agreement include provisions that encourage WTO members to base their national regulations on international standards. The article focuses on key issues in the Codex that may have a significant impact on international food trade. The overall conclusion is that the WTO has contributed to constraining the activity and shaping the expectations of Codex members. Governments participating in Codex activities have changed their behavior after 1995 due to increased uncertainty with respect to how decisions in Codex may be binding for them under the WTO Agreements.
The Effect of Human Rights on Criminal Evidentiary Processes: Towards Convergence, Divergence or Realignment?
Authors: Jackson John D.
Published: August 2005

This article examines the contribution which the European Court of Human Rights has made to the development of common evidentiary processes across the common law and civil law systems of criminal procedure in Europe. It is argued that the continuing use of terms such as ‘adversarial’ and ‘inquisitorial’ to describe models of criminal proof and procedure has obscured the genuinely transformative nature of the Court's jurisprudence. It is shown that over a number of years the Court has been steadily developing a new model of proof that is better characterised as ‘participatory’ than as ‘adversarial’ or ‘inquisitorial’. Instead of leading towards a convergence of existing ‘adversarial’ and ‘inquisitorial’ models of proof, this is more likely to lead towards a realignment of existing processes of proof which nonetheless allows plenty of scope for diverse application in different institutional and cultural settings.
Disadvantaged but different: variation among deprived communities in relation to child and family well‐being
Authors: Barnes Jacqueline , Belsky Jay , Broomfield Kate A. , Dave Sapna , Frost Martin , Melhuish Edward ,   The National Evaluation of Sure Start Research Team
Published: August 2005

Background:  Disadvantaged communities are increasingly the target for interventions. Sure Start was launched in England in 1999 to tackle child poverty and improve child and family services, with Sure Start Local Programmes (SSLPs) targeted at relatively small areas of marked deprivation. However, they are located in a range of different types of communities where they may provide services to very different resident populations. They are all disadvantaged but underlying that label there are specific patterns of variability, relevant for service provision. To evaluate the implementation, impact, and cost‐effectiveness of SSLPs, or other area‐based initiatives, it is important to consider ways in which they can be grouped meaningfully according to these patterns.

Method:  Data were collected from administrative databases to describe SSLPs in terms of demography, deprivation, and aspects of child and family functioning and grouped using cluster analysis.

Results:  Five different ‘types’ of SSLP community were identified, based on their socio‐demographic and economic characteristics; typified by more, less or average deprivation in relation to all SSLPs, and in terms of the proportion of ethnic minority families resident in the areas. The groups differ in terms of community measures of child health, educational attainment, school disorder and child welfare and their prediction from demographic community characteristics.

Conclusions:  The groupings have implications for service delivery and the evaluation of area‐based initiatives.
Influence of general self‐efficacy on the effects of a school‐based universal primary prevention program of depressive symptoms in adolescents: a randomized and controlled follow‐up study
Authors: Pössel Patrick , Baldus Christiane , Horn Andrea B. , Groen Gunter , Hautzinger Martin
Published: August 2005

Background:  Depressive disorders in adolescents are a widespread and increasing problem. Prevention seems a promising and feasible approach.

Methods:  We designed a cognitive‐behavioral school‐based universal primary prevention program and followed 347 eighth‐grade students participating in a randomized controlled trial for three months.

Results:  In line with our hypothesis, participants in the prevention program remained on a low level of depressive symptoms, having strong social networks. The control group showed increasing depressive symptoms and a reduced social network. Contrary to our expectations, students low in self‐efficacy benefited more from the program than high self‐efficient students. Social network did not mediate the relationship between participation in the prevention program and changes in depressive symptoms.

Conclusions:  Our results show that the prevention program had favorable effects. Further research is needed to explore the impact of self‐efficacy on the effects of prevention programs.
Lifetime prognosis of schizophrenia: extended observation (more than 40 years) of 129 patients with typical schizophrenia
Authors: ICHIMIYA Yosuke , ICHIMIYA Yuko , SAKURAI Nobuyuki , TAKAGI Ichiro
Published: August 2005

Background:  The excess mortality among patients with schizophrenia has been documented by epidemiological studies. These studies have shown that suicide accounts for most of this mortality. In contrast, the natural deaths of patients with schizophrenia have been commonly related to cardiovascular disease in these studies.

Methods:  In this study, the clinical features of 129 patients with typical schizophrenia were examined in order to study the lifetime prognosis of patients with schizophrenia in Japan. These patients had their first visit to Kawagoe Dojinkai Hospital in 1963 and had been continuously observed for over 40 years.

Results:  As at January 2003, the status of these 129 patients was categorized as follows: 27 patients were inpatients (mean age was 72.9 years), 20 patients were outpatients (mean age was 68.8 years), 2 patients were outpatients of another hospital, 20 patients had been admitted into nursing homes, 53 patients had passed away and 7 patients were missing. Clinical features were recorded for 44 (23 male patients with a mean age of 68.6 years and 21 female patients with a mean age of 64.2 years) out of the 53 patients who had passed away. The causes of death consisted of malignancy (13 cases), pneumonia (eight cases), heart failure (five cases), cerebral infarction (three cases), diabetes mellitus (three cases), cardiac infarction (two cases), ileus (two cases), asphyxia (one case), liver cirrhosis (one case), gastric ulcer (one case), heat stroke (one case), homicide (one case) and suicide (three cases). Two patients were discovered to have passed away alone at home.

Conclusion:  The mean age of death was found to be lower than the life expectancy. However, only three patients committed suicide. These findings suggest that patients with schizophrenia may possess some biological vulnerability. Further study is needed to evaluate the effects of long‐term antipsychotic medication. Clinically, medical checks for malignancy and care services for elderly patients are needed. Furthermore, in order to prevent future occurrences of patients dying alone in their own home, a social support system should be established.
Correlation between tau phosphorylation sites and tangle morphology in Alzheimer's disease
Authors: SHIMAZAKI Masao , NAKANO Hiroyuki , Kobayashi Katsuji
Published: August 2005

Background:  To study the relationship between phosphorylation sites of the tau protein and changes in the configuration of neurofibrillary tangles (NFT) in brains with Alzheimer's disease (AD).

Methods:  Seven brains from patients with non‐familial AD and three control brains were examined. NFT were immunolabeled with five monoclonal antibodies against phosphorylated serine (pSer) and threonine (pThr): AT180 targets pThr231; AT8 targets pSer202 and pThr205; HT7 targets pSer159–163; Tau2 targets pSer101; and Tau5 targets the central region of the tau sequence. Tau‐labeled NFT (tNFT) were grouped into pretangles (p‐NFT), intracellular tangles (i‐NFT) and extracellular ghost tangles (e‐NFT) according to their cytological features. Gallyas‐stained NFT (gNFT) were regarded as the NFT population of AD. The cerebral regions examined included the cornu ammonis (CA), entorhinal cortex, anterior cingulate cortex, inferior parietal lobe, temporal neocortex, occipital cortex and lateral prefrontal lobe. The first three regions were grouped into the limbic cortex and the others into the association cortex.

Results:  p‐NFT were observed with all tau labeling, with the p‐NFT/tNFT percentage ranging from 14% to 19%, and densities of p‐NFT and i‐NFT were higher in the limbic cortex than in the association cortex. The p‐NFT/tNFT ratio in Tau2 labeling was the lowest compared with the other tau labeling. e‐NFT showed an irregular density distribution across both cerebral regions and different tau labeling, and the densities of p‐NFT and e‐NFT were correlated with that of tNFT. In contrast, e‐NFT were correlated with p‐NFT in AT180 and Tau5 labeling.

Conclusion:  The higher densities of p‐NFT and i‐NFT in the limbic cortex compared to the association cortex are compatible with the regional extension of NFT. pSer101 is closely associated with the late process of p‐NFT generation, and pSer202 and pThr205 are presumed to be triggers for the generation of p‐NFT. Phosphorylation of pSer101 detected by Tau2 plays an important role in the formation of e‐NFT and p‐NFT.
Enhancing Synergistic Innovative Capability in Multinational Corporations: An Empirical Investigation
Authors: Persaud Ajax
Published: August 2005

A substantial amount of research has focused on determining and classifying the structures of the global research and development (R&D) organization of multinational corporations (MNCs). However, little research has been undertaken to show how the various R&D structures adopted by MNCs affect their abilities to generate and deploy innovations globally. This study initiates analysis and discussion of this latter dimension, providing empirical evidence of the relationship between the coordination structures and innovative capabilities. Specifically, this study investigates how intrafirm collaborative relationships among globally dispersed R&D units of MNCs enhance the synergistic innovative capabilities of the MNC group. The nature of the collaborative relationships among globally dispersed R&D units is evaluated in the context of four well‐established structural constructs: autonomy, formalization, socialization, and communication. Synergistic innovative capability is defined as a higher‐order ability to accumulate and deploy new knowledge or to recombine existing knowledge to create new innovations more effectively and efficiently due to collaboration among globally dispersed R&D units. It is measured using 10 items commonly used in innovation management research to measure the innovativeness of firms. The analysis is based on survey data collected from 79 R&D units belonging to North American, Japanese, and European MNCs in the telecommunications, biotechnology, pharmaceutical, chemical, and automotive industries. In addition to the survey data, seven highly experienced R&D executives who have worked for several companies were interviewed by telephone in order to obtain a richer perspective of issues and a better context from which to interpret the statistical results. Respondents included personnel from the levels of director, managing director, and vice president who were directly responsible for participating R&D units. The data were analyzed using partial least squares, a structural equation modeling technique that works well with small datasets. The results indicate that synergistic innovative capability has four distinct dimensions uniquely related to the structural variables defining the nature of collaborative relationships among globally dispersed R&D units. The four dimensions of synergistic innovative capabilities are labeled strategic R&D synergy, managerial and operational synergy, knowledge management synergy, and innovative proficiency synergy. The research and managerial implications of the findings are discussed in this article.
Why the World Needs Protists!1
Authors: CORLISS JOHN O.
Published: August 2005

ABSTRACT.In this brief review, literature references are given to researches—involving diverse species of protists—that support the author's firm conviction that the biological world of today absolutely requires the presence of numerous of these generally small and unicelled organisms if it is to survive. Examples supplied come from areas within the field of protistologysensu latoas widely separated as basic phycological research on photosynthesis and protozoological/medical/biomedical investigations on malaria and other pathogens of human beings. Emphasis is primarily on the most relevant works of the past 10—15 years, although historically highly significant papers of older vintage require at least indirect—and occasionally direct—citation.
The Dynein Heavy Chain Family1
Authors: ASAI DAVID J. , WILKES DAVID E.
Published: August 2005

ABSTRACT. Dynein is the large molecular motor that translocates to the (‐) ends of microtubules. Dynein was first isolated from Tetrahymena cilia four decades ago. The analysis of the primary structure of the dynein heavy chain and the discovery that many organisms express multiple dynein heavy chains have led to two insights. One, dynein, whose motor domain comprises six AAA modules and two potential mechanical levers, generates movement by a mechanism that is fundamentally different than that which underlies the motion of myosin and kinesin. And two, organisms with cilia or flagella express approximately 14 different dynein heavy chain genes, each gene encodes a distinct dynein protein isoform, and each isoform appears to be functionally specialized. Sequence comparisons demonstrate that functionally equivalent isoforms of dynein heavy chains are well conserved across species. Alignments of portions of the motor domain result in seven clusters: (i) cytoplasmic dynein Dyhl; (ii) cytoplasmic dynein Dyh2; (iii) axonemal outer arm dynein a; (iv) outer arm dyneins β and ‐γ; (v) inner arm dynein lα; (vi) inner arm dynein 1β; and (vii) a group of apparently single‐headed inner arm dyneins. Some of the dynein groups contained more than one representative from a single organism, suggesting that these may be tissue‐specific variants.
Comparative Genomics of Pneumocystis carinii with Other Protists: Implications for Life Style1
Authors: CUSHION MELANIE T.
Published: August 2005

ABSTRACT. Three protistan genomes were analyzed for differential genetic traits that may be associated with biological adaptations to their unique life styles. The microsporidian, Encephalitozoon cuniculi, an obligate intracellular parasite; the ascomycetes, Pneumocystis carinii, considered an opportunistic pathogen; and Saccharomyces cerevisiae, a model organism exhibiting a free‐living life style, were used in comparisons of genomic architecture, reproductive strategies, and metabolic capacity predicted by the presence of signature genes. Genome size, gene number, and metabolic function decreased as the organisms became more dependent on their hosts. In contrast, gene density and the percentage of genes dedicated to cell growth and division were substantially increased in the genome of E. cuniculi. The obligate life style was associated with reductions in gene number, genome size, and reduced metabolic capacity while the free‐living life style was coincident with gene duplications and duplication of large portions of the genome. The genomic characteristics and metabolic capacity of P. carinii were usually intermediate between those of the other two protistan genomes, but unique characteristics such as the presence of a single rDNA locus may indicate that these organisms could be in the process of becoming more host dependent.
Relationship between the Host Cell Mitochondria and the Parasitophorous Vacuole in Cells Infected with Encephalitozoon Microsporidia
Authors: SCANLON MARY , LEITCH GORDON J. , VISVESVARA GOVINDA S. , SHAW ANDREW P.
Published: August 2005

ABSTRACT. Encephalitozoon microsporidia proliferate and differentiate within a parasitophorous vacuole. Using the fluorescent probe, calcein, and the mitochondrial probe, MitoTracker‐CMXRos, a vital method was developed that confirmed ultrastructural reports that the host cell mitochondria frequently lie in immediate proximity to the parasitophorous vacuole. Morphometry failed to demonstrate any infection‐induced increase in host cell mitochondria as there was no correlation between the mitochondrial volume and the extent of infection as judged by the parasitophorous vacuole volume. The total ATP concentration of infected cells did not differ from that of uninfected cells in spite of the increased metabolic demands of the infection. Treatment with 10‐6 M albendazole, more than ten times the antiparasitic IC50 dose, and demecolcine had no subjective effect on the proximity of mitochondria to the parasitophorous vacuole membrane when studied by either transmission electron microscopy or by confocal microscopy even though these drug concentrations affected microtubule structure. Thus, once the association between mitochondria and the parasitophorous vacuole has been established, host cell microtubule integrity is probably not required for its maintenance. It is unlikely that the antimicrosporidial action of albendazole involves physically uncoupling developing parasite stages from host cell organelle metabolic support.
Molecular Phytogeny and Evolution of Mosquito Parasitic Microsporidia (Microsporidia: Amblyosporidae)1
Authors: VOSSBRINCK CHARLES R. , ANDREADIS THEODORE G. , VAVRA JIRI , BECNEL JAMES J.
Published: August 2005

ABSTRACT. Amblyospora species and other aquatic Microsporidia were isolated from mosquitoes, black flies, and copepods and the small subunit ribosomal RNA gene was sequenced. Comparative phylogenetic analysis showed a correspondence between the mosquito host genera and their Amblyospora parasite species. There is a clade of Amblyospora species that infect the Culex host group and a clade of Amblyospora that infect the Aedes/Ochlerotatus group of mosquitoes. Parathelohania species, which infect Anopheles mosquitoes, may be the sister group to the Amblyospora in the same way that the Anopheles mosquitoes are thought to be the sister group to the Amblyosporo and Aedes mosquitoes. In addition, by sequence analysis of small subunit rDNA from spores, we identified the alternate copepod host for four species of Amblyospora. Amblyospora species are specific for their primary (mosquito) host and each of these mosquito species serves as host for only one Amblyospora species. On the other hand, a single species of copepod can serve as an intermediate host to several Amblyospora species and some Amblyospora species may be found in more than one copepod host. Intrapredatorus barn, a species within a monotypic genus with Amblyospora‐like characteristics, falls well within the Amblyospora clade. The genera Edhazardia and Culicospora, which do not have functional meiospores and do not require an intermediate host, but which do have a lanceolate spore type which is ultrastructurally very similar to the Amblyospora spore type found in the copepod, cluster among the Amblyospora species. In the future, the genus Amblyospora may be redefined to include species without obligate intermediate hosts. Hazardia, Berwaldia, Larssonia, Trichotuzetia, and Gurleya are members of a sister group to the Amblyospora clades infecting mosquitoes, and may be representatives of a large group of aquatic parasites.
The Flagellar Apparatus of Heteroloboseans
Authors: BRUGEROLLE GUY , SIMPSON ALASTAIR G. B.
Published: August 2005

ABSTRACT. The flagellar apparatus of four heterolobosean species Percolomonas descissus, Percolomonas sulcatus, Tetramitus rostratus, and Naegleria gruberi were examined. P. descissus lives in oxygen‐poor water. It is a quadriflagellated cell with a ventral groove. The two pairs of basal bodies are connected to an apical structure from which the peripheral dorso‐lateral microtubules and a short striated rhizoplast originate. There is one major microtubular root, Rl, which originates from the posterior basal body pair and splits into left and right portions that support the sides of the ventral groove. The anterior pair of basal bodies is associated with a root of four to five microtubules that runs to the left of the groove. This organisation is similar to that previously reported for Psalteriomonas, Lyromonas, and Percolomonas cosmopolitus. Percolomonas sulcatus has two parallel pairs of basal bodies, each of which is associated with a well‐developed Rl root. These roots divide to give two distinct left portions and one merged right portion that support the margins of the slit‐like ventral groove. Tetramitus rostratus has two pairs of basal bodies, several rhizoplast fibres, and two Rl roots. Each Rl root supports one wall of the ventral groove. Naegleria gruberi may have two pairs of basal bodies, each associated with a microtubular root and one long rhizoplast fibre. From available data, a ‘double bikont’‐like organisation of the heterolobosean flagellar apparatus is inferred, where both of the eldest basal bodies have largely ‘mature’ complements of microtubular roots. The cytoskeletal organisation of heteroloboseans is compared to those of (other) excavates. Our structural data and existing molecular phytogenies weaken the case that Percolomonas, Psalteriomonas, and Lyromonas are phylogenetically separable from other heteroloboseans, undermining many of the highest‐level taxa proposed for these organisms, including Percolozoa, Striatorhiza, Percolomonada, Percolomonadea, and Lyromonadea.
Transparent Magnetic Glass‐Ceramics
Authors: Dejneka Matthew J. , Powell Christy , Borrelli Nick , Ouzounov Dimitre , Gaeta Alex
Published: August 2005

Transparent magnetic glass‐ceramics were produced by infiltrating nano‐porous glass with nitrate salts and firing. The resultant glass‐ceramics contained spinel ferrite nanocrystals that exhibited ferromagnetic and superparamagnetic behavior depending on composition and firing temperature. Transparency in the near infrared was obtained when oxidizing conditions were used to prevent Fe2+ formation, while the porous matrix ensured nano‐sized crystallites to limit scattering losses. MnFe2O4 glass‐ceramics treated at 1000°C offered the best combination of magnetic and optical properties with a saturation magnetization of 5.6 emu/g, a Verdet constant of 16.5°/cm, and losses below 3 dB/mm at 1550 nm.
Radiation‐Induced Surface Conductivity in an Alkaline‐Earth Boroaluminosilicate Glass Measured with Elevated‐Temperature Scanning Probe Microscopy
Authors: Polking Mark J. , Umbach Christopher C.
Published: August 2005

A 50 mW 325 nm He:Cd laser was used to irradiate the fracture surface of a commercial alkaline‐earth boroaluminosilicate display glass (Corning Code 1737) held at temperatures above 800 K. After this treatment, the surface of the glass was found to be conductive for several hours in a temperature range between room temperature and 850 K. The conductivity shows an activation energy of 0.18 eV. Scanning tunneling spectroscopy measurements indicate that the glass surface is semiconducting with a bandgap of ∼4.4 eV. It is possible to form topographical images of the surface of the glass using the electron tunneling current; the observed topography corresponds to that acquired using atomic force imaging from the same area.
Structural Studies of (Ca,Sr)F2 Single Crystals with Raman and NMR Spectroscopies
Authors: Ponader Carl W. , Youngman Randall E. , Smith Charlene M.
Published: August 2005

Single crystal CaF2 is the material of choice for optics in the vacuum UV, due in part to its high transmission at these wavelengths. Unfortunately, as the wavelengths decrease, intrinsic birefringence (also referred to as spatial dispersion) can become larger than the target birefringence for precision optics at 157 nm, even for a cubic material such as CaF2. One elegant solution to this problem is to capitalize on opposite signs for this intrinsic birefringence, such as mixing SrF2 or BaF2 with CaF2. If the proper fluorides are mixed with the correct concentration, the intrinsic birefringence of the mixed single crystals can be minimized. It is also important that the resulting mixed single crystal maintain the high symmetry of CaF2, which requires that the cations mix randomly in the CaF2 structure. We show through Raman and NMR spectroscopic studies that this random mixing of cations can be achieved for mixed (Ca,Sr)F2 single crystals. A single Raman band is observed for all mixed crystals, which changes in both position and width upon addition of SrF2 to CaF2. 19F NMR spectra also reflect a random distribution of cations around the different fluorine environments in the mixed crystals.
Chalcogenide Glass Thin Films and Planar Waveguides
Authors: Curry R. J. , Mairaj A. K. , Huang C. C. , Eason R. W. , Grivas C. , Hewak D. W. , Badding J. V.
Published: August 2005

Over the past decade, we have carried out a comprehensive development program to produce high‐purity Ga:La:S and Ge:S glasses and further process these glasses into thin films. In this paper, we discuss the general properties of these glass systems and the techniques used to obtain thin films. We demonstrate the ability to deposit high‐quality films ranging in thickness from nanometers to several millimeters by several methods, including chemical vapor deposition technique, a technique not usually applied to chalcogenide glasses.
Influence of the Rare‐Earth Element on the Mechanical Properties of RE–Mg‐Bearing Silicon Nitride
Authors: Satet Raphaëlle L. , Hoffmann Michael J.
Published: August 2005

Silicon nitride bulk ceramics with varying compositions of the grain boundary phase but similar grain sizes were developed, which allows to analyze the influence of the grain boundary chemistry on mechanical properties. Micrographs of the crack path reveal a much weaker interface when the rare‐earth element in the grain boundary phase changes from a small to a large rare‐earth cation (RE3+). Room temperature measurements of toughness and bending strength show that weaker grain boundaries result in a higher toughness, but in a decreased strength of the bulk material. This investigation demonstrates that the mechanical behavior of silicon nitride can be readily tuned by chemical composition changes of the grain boundary phase, but that a compromise between toughness and strength has to be found when designing the material.
Immobilization of Pb in a Geopolymer Matrix
Authors: Perera Dan S. , Aly Zaynab , Vance Eric R. , Mizumo Masahiro
Published: August 2005

In a geopolymer matrix prepared by mixing a metakaolinite precursor with a solution of potassium hydroxide and silicate, 1 wt% Pb as the nitrate has been immobilized. Under the United States Environmental Protection Agency test protocol the Pb release was less than 5 ppm, the acceptable limit for landfills in the U.S.A. Electron microscopy showed Pb was present in the major amorphous phase and a minor (∼1 vol%) Ca‐rich potassium silicate phase. Heating cured samples to several hundred degrees Centigrade was not significantly advantageous for immobilizing Pb.
Effects of Yttrium on the Sintering and Microstructure of Alumina–Silicon Carbide “Nanocomposites”
Authors: Cock Alex M. , Shapiro Ian P. , Todd Richard I. , Roberts Steve G.
Published: August 2005

Alumina and alumina‐based “nanocomposites” with 2 and 5 vol% silicon carbide and varying amounts of yttria (0–1.5 wt%) have been prepared by pressureless sintering in the temperature range 1450°–1650°C. The effects of composition and sintering temperature on density and microstructure are reported. Yttria inhibited sintering in alumina, but enhanced the sinterability of the nanocomposites. It also induced abnormal grain growth in both alumina and nanocomposites, but strongly bimodal grain size distributions could be prevented by careful choice of the composition and the sintering temperature. Fully dense (>99%), fine‐grained alumina–5 vol% SiC–1.5 wt% yttria nanocomposites were produced from uniaxially pressed powders with a yttria content of 1.5 wt% and a sintering temperature of 1600°C. Reasons for this behavior are discussed, and it is suggested that the enhancement of sintering in the alumina–SiC materials is because of the reaction of silica on the surface of the silicon carbide particles with alumina, yttria, and possibly magnesia, modifying the grain boundary composition, resulting in enhanced grain boundary diffusion. scanning transmission electron microscopy/energy‐dispersive X‐ray data show that such co‐segregation does occur in the yttria‐containing nanocomposites.
A Novel Low‐Temperature Synthesis of Nanosized NiZn Ferrite
Authors: Verma Seema , Pradhan S. D. , Pasricha Renu , Sainkar S. R. , Joy P. A.
Published: August 2005

Nanosized NiZn ferrite powder is synthesized by a low‐temperature method, using a unique combination of citric acid and glycine. An appropriate molar ratio of both citric acid and glycine offers a low‐temperature synthetic route by incorporating the complexation behavior of citric acid and the combustion nature of glycine. Thermal decomposition/controlled autocatalytic combustion of the composite gel occurs at a low temperature of around 175°C, with the evolution of a large amount of gases. Transmission electron microscopic studies showed that the average particle size of the ferrite obtained is ∼2.5 nm, with a narrow size distribution. Uniformly distributed fine‐grained microstructure with low porosity is obtained for a sample sintered at 1000°C.
Processing of Nanoparticulate Bismuth Ferrite Lead Titanate (BFPT) Through High‐Energy Milling
Authors: Khan Mikael A. , Comyn Timothy P. , Bell Andrew J.
Published: August 2005

An investigation into the processing of a bismuth ferrite lead titanate (BFPT) solid solution close to the morphotropic phase boundary through mechanical activation was undertaken. High‐energy milling of constituent oxides was performed in a shaker mill, which resulted in size reduction of the particles to the nanoscale (40–600 nm). Subsequent calcination indicated a significant decrease in the temperature required for complete formation of the perovskite BFPT phase. It is concluded that the size reduction increases the particle surface area and reduces the diffusion paths for reaction sufficiently to result in a substantial decrease in the temperature required for perovskite formation. However perovskite phase formation as a result of mechanical activation alone was not observed.
Effect of Alumina Additions on Microstructural Aspects of the β to α Transformation in Tantalum (V) Oxide
Authors: Wu Suxing , Chan Helen M. , Harmer Martin P.
Published: August 2005

Tantalum (V) oxide (Ta2O5) has potential applications as part of an environmental barrier coating system for Si3N4‐based turbine components. However, at elevated temperatures, Ta2O5 undergoes a phase transformation from the orthorhombic (β) phase to the tetragonal phase (α), which is undesirable because of the associated volume change. The purpose of the present work was to study the effect of alumina additions (0–5 wt%) on the β to α transformation temperature, and associated modifications to the Ta2O5 microstructure. Sintered microstructures were characterized using SEM (scanning electron microscopy), and XRD (X‐ray diffraction) was used to identify the phases present at room temperature. It was found that for undoped Ta2O5, transformation of the low‐temperature β‐phase begins at ∼1300°C, and leads to extensive microcracking of the sintered sample. For samples containing alumina, an increase in the transformation temperature was observed. The solubility limit of alumina in Ta2O5 was between 1 and 3 wt%; for samples in which this was exceeded, the AlTaO4 second and phase particles were seen to be highly effective at inhibiting grain growth.
Transformation of Electron‐Beam Physical Vapor‐Deposited 8 wt% Yttria‐Stabilized Zirconia Thermal Barrier Coatings
Authors: Lughi Vanni , Clarke David R.
Published: August 2005

Yttria‐stabilized (8.6 mol% YO1.5) zirconia thermal barrier coatings evolve at high temperatures from the “non‐transformable,” metastable tetragonal‐prime phase in their as‐deposited condition to a mixture of the tetragonal and cubic phases. The kinetics of the transformation at 1200° and 1425°C are reported based on X‐ray diffraction measurements. Complementary Raman spectroscopy measurements indicate a sharpening of the tetragonal bands at 263 and 465 cm−1 that is attributed to a systematic decrease in disorder of the Y3+ and oxygen vacancies with annealing. No transformation to the monoclinic form of zirconia is observed immediately after high‐temperature treatment. However, partial transformation to monoclinic occurs after a prolonged time (months) at room temperature in those samples treated at 1425°C, indicating the development of isothermal martensite.
Optical Properties of Er‐Doped Al2O3–SiO2 Films Prepared by a Modified Sol–Gel Process
Authors: Seok Sang Il , Lim Mi Ae , Ju Jung‐Jin , Lee Myung‐Hyun
Published: August 2005

Er‐doped Al2O3–SiO2 (1/9 in mol ratio of Al2O3/SiO2) thin films were prepared by using a modified sol–gel process. The modified process entails the precipitation and digestion of Er(OH)3, obtained from the reaction between Er ions and NH4OH in solution. Thin films were deposited on Si wafers by using a spin coating technique (3000 rpm) and the coated films were heat treated at different temperatures for 1 h in an oxygen‐purged furnace. All the films were structurally characterized by the X‐ray diffraction technique using CuKα radiation. Refractive indices and the morphologies of the films were studied using a spectroscopic phase modulated ellipsometer and atomic force microscopy, respectively. It was observed that the films were crack free and of about 0.4 μm thickness in a single spin coating and both the lifetime and the photoluminescence intensity of Er ions increased with increasing the annealing temperature. The luminescence properties of the Er‐doped Al2O3–SiO2 made by a conventional and our modified doping process were compared and discussed from the stand point of peak intensities and lifetimes as a function of annealing temperatures. It is to be noted here that our modified process was found to be more effective in reducing the clustering of Er ions in Al2O3–SiO2 materials as compared to that of the conventional method.
A Bimodal Grain Size Model for Predicting the Dielectric Constant of Calcium Copper Titanate Ceramics
Authors: Pan Ming‐Jen , Bender Barry A.
Published: August 2005

The bimodal distribution of grain size is frequently observed in calcium copper titanate (CaCu3Ti4O12 or CCTO) ceramics that exhibit high dielectric constant. In this study, we propose an analytical model composed of grains of two different sizes to estimate the dielectric behavior of CCTO based on microstructural features. Important assumptions are (1) CCTO is a barrier layer dielectric and (2) the insulating layer thickness is the same in both large and small grains. Explicit expressions for the effective dielectric constant of serial, parallel, and logarithmic mixture models are given. When compared with experimental results, the present bimodal model appears to be acceptable for describing the dielectric behavior of CCTO.