586 resultados para Shingon (Sect)
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Background and aims South America and Oceania possess numerous floristic similarities, often confirmed by morphological and molecular data. The carnivorous Drosera meristocaulis (Droseraceae), endemic to the Neblina highlands of northern South America, was known to share morphological characters with the pygmy sundews of Drosera sect. Bryastrum, which are endemic to Australia and New Zealand. The inclusion of D. meristocaulis in a molecular phylogenetic analysis may clarify its systematic position and offer an opportunity to investigate character evolution in Droseraceae and phylogeographic patterns between South America and Oceania. Methods Drosera meristocaulis was included in a molecular phylogenetic analysis of Droseraceae, using nuclear internal transcribed spacer (ITS) and plastid rbcL and rps16 sequence data. Pollen of D. meristocaulis was studied using light microscopy and scanning electron microscopy techniques, and the karyotype was inferred from root tip meristem. Key Results The phylogenetic inferences (maximum parsimony, maximum likelihood and Bayesian approaches) substantiate with high statistical support the inclusion of sect. Meristocaulis and its single species, D. meristocaulis, within the Australian Drosera clade, sister to a group comprising species of sect. Bryastrum. A chromosome number of 2n = approx. 32–36 supports the phylogenetic position within the Australian clade. The undivided styles, conspicuous large setuous stipules, a cryptocotylar (hypogaeous) germination pattern and pollen tetrads with aperture of intermediate type 7–8 are key morphological traits shared between D. meristocaulis and pygmy sundews of sect. Bryastrum from Australia and New Zealand. Conclusions The multidisciplinary approach adopted in this study (using morphological, palynological, cytotaxonomic and molecular phylogenetic data) enabled us to elucidate the relationships of the thus far unplaced taxon D. meristocaulis. Long-distance dispersal between southwestern Oceania and northern South America is the most likely scenario to explain the phylogeographic pattern revealed.
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The circumscription of genera belonging to tribe Bignonieae (Bignoniaceae) has traditionally been complex, with only a few genera having stable circumscriptions in the various classification systems proposed for the tribe. The genus Lundia, for instance, is well characterized by a series of morphological synapomorphies and its circumscription has remained quite stable throughout its history. Despite the stable circumscription of Lundia, the circumscription of species within the genus has remained problematic. This study aims to reconstruct the phylogeny of Lundia in order to refine species circumscriptions, gain a better understanding of relationships between taxa, and identify potential morphological synapomorphies for species and major clades. We sampled 26 accessions representing 13 species of Lundia, and 5 outgroups, and reconstructed the phylogeny of the genus using a chloroplast (ndhF) and a nuclear marker (PepC). Data derived from sequences of the individual loci were analyzed using parsimony and Bayesian inference, and the combined molecular dataset was analyzed with Bayesian methods. The monophyly of Lundia nitidula, a species with a particularly complex circumscription, was tested using Shimodaira-Hasegawa (SH) test and the approximately unbiased test for phylogenetic tree selection (AU test). In addition, 40 morphological characters were mapped onto the tree that resulted from the analysis of the combined molecular dataset in order to identify morphological synapomorphies of individual species and major clades. Lundia and most species currently recognized within the genus were strongly supported as monophyletic in all analyses. One species, Lundia nitidula, was not resolved as monophyletic, but the monophyly of this species was not rejected by the AU and SH tests. Lundia sect. Eriolundia is resolved as paraphyletic in all analyses, while Lundia sect. Eulundia is monophyletic and supported by the same morphological characters traditionally used to circumscribe this section. The phylogeny of Lundia contributed important information for a better circumscription of species and served as basis the taxonomic revision of the genus.
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South America and Oceania possess numerous floristic similarities, often confirmed by morphological and molecular data. The carnivorous Drosera meristocaulis (Droseraceae), endemic to the Neblina highlands of northern South America, was known to share morphological characters with the pygmy sundews of Drosera sect. Bryastrum, which are endemic to Australia and New Zealand. The inclusion of D. meristocaulis in a molecular phylogenetic analysis may clarify its systematic position and offer an opportunity to investigate character evolution in Droseraceae and phylogeographic patterns between South America and Oceania. was included in a molecular phylogenetic analysis of Droseraceae, using nuclear internal transcribed spacer (ITS) and plastid rbcL and rps16 sequence data. Pollen of D. meristocaulis was studied using light microscopy and scanning electron microscopy techniques, and the karyotype was inferred from root tip meristem. The phylogenetic inferences (maximum parsimony, maximum likelihood and Bayesian approaches) substantiate with high statistical support the inclusion of sect. Meristocaulis and its single species, D. meristocaulis, within the Australian Drosera clade, sister to a group comprising species of sect. Bryastrum. A chromosome number of 2n approx. 3236 supports the phylogenetic position within the Australian clade. The undivided styles, conspicuous large setuous stipules, a cryptocotylar (hypogaeous) germination pattern and pollen tetrads with aperture of intermediate type 78 are key morphological traits shared between D. meristocaulis and pygmy sundews of sect. Bryastrum from Australia and New Zealand. The multidisciplinary approach adopted in this study (using morphological, palynological, cytotaxonomic and molecular phylogenetic data) enabled us to elucidate the relationships of the thus far unplaced taxon D. meristocaulis. Long-distance dispersal between southwestern Oceania and northern South America is the most likely scenario to explain the phylogeographic pattern revealed.
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Baccharis umbellata, a new species of Parana State, southern Brazil, is described. The new species, belonging to subgen. Baccharis sect. Agglomeratae, is easily recognized by the pedunculate heads arranged in an umbel-like capitulescence. Baccharis umbellata is a narrow endemic of the peaks of the southern range of Serra do Mar. It is morphologically most similar to the allopatric species B. platypoda, which mainly inhabits mountain summits in western and eastern South America. Illustrations, a distribution map, habitat information, and a conservation assessment are also provided for the new species.
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Sect. 606, par. 1, e), as modified by Law 46, enacted on Februray 20th, 2006 introduced the chance to appeal to the Court of cassation in case of inconsistent reasoning and extended control on its existence and on other flaws and lack of obvious logic over the text of the contested decision, namely “to other acts the process specified in the grounds of burden”. The renewed provision seems to properly reappoint the “distortion of the evidence”, i.e. the omitted or distorted evidence that could be relevant and conclusive one, in the peculiar context of the grounds' vice. After a general review of the obligation to state reasons for judicial decisions, we analyze the innovative status of the vice of “distortion of evidence” and the conditions and the limits - defined by the law - within we can contest a resolution for illegitimacy. Then, we outline the systematic spin-off brought by the new form of sect. 606, par. 1, e) on some institutions in the code of criminal procedure. Finally, we make the role of the Court of cassation clear in the modern criminal trial, since the 2006 reform gave no definite answer on this fundamental aspect of the question.
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This research focuses on taxonomy, phylogeny and reproductive ecology of Gentiana lutea. L.. Taxonomic analysis is a critical step in botanical studies, as it is necessary to recognize taxonomical unit. Herbarium specimens were observed to assess the reliability of several subspecies-diagnostic characters. The analysis of G. lutea genetic variability and the comparison with that of the other species of sect. Gentiana were performed to elucidate phylogenetic relationships among G. lutea subspecies and to propose a phylogenetic hypothesis for the evolution and the colonization dynamics of the section. Appropriate scientific information is critical for the assessment of species conservation status and for effective management plans. I carried out field work on five natural populations and performed laboratory analyses on specific critical aspects, with special regard to G. lutea breeding system and type and efficiency of plant-pollinator system. Bracts length is a reliable character to identify subsp. vardjanii, however it is not exclusive, hence to clearly identify subsp. vardjanii, other traits have to be considered. The phylogenetic hypotheses obtained from nuclear and chloroplast data are not congruent. Nuclear markers show a monophyly of sect. Gentiana, a strongly species identity of G. lutea and clear genetic identity of subsp. vardjanii. The little information emerging from plastid markers indicate a weak signal of hybridization and incomplete sorting of ancestral lineages. G. lutea shows a striking variation in intra-floral dichogamy probably evolved to reduce pollen-stigma interference. Although the species is partially self-compatible, pollen vectors are necessary for a successful reproduction, and moreover it shows a strong inbreeding depression. G. lutea is a generalist species: within its spectrum of visitors is possible to recognize "nectar thieves" and pollinators with sedentary or dynamic behaviour. Pollen limitation is frequent and it could be mainly explained by poor pollen quality.
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Die Systematik, Phylogenie und Biogeographie der Gattung Cousinia (Asteraceae, Cardueae) als größter Gattung der Tribus Cardueae mit mehr als 600 Arten wurde untersucht. Diese Dissertation umfasst drei Hauptteile: Im ersten Teil wurde die Phylogenie und Evolution des Arctium-Cousinia-Komplexes Untersucht. Dieser Gattungskomplex enthält Arctium, Cousinia, Hypacanthium und Schmalhausenia und zeigt die höchste Diversität in der Irano-Turanischen Region und in den Gebirgen Zentralasiens. Es wurden ITS und rpS4-trnT-trnL-Sequenzen für insgesamt 138 Arten generiert, darunter von 129 (von ca. 600) Arten von Cousinia. Wie in früheren Analysen bereits gefunden, ist Cousinia nicht monophyletisch. Stattdessen sind Cousinia subg. Cynaroides und subg. Hypacanthodes mit insgesamt ca. 30 Arten enger mit Arctium, Hypacanthium und Schmalhausenia (Arctioid Clade) als mit subg. Cousinia (Cousinioid Clade) verwandt. Die Arctioid und Cousiniod clades werden auch durch Pollenmorphologie und Chromosomenzahl unterstützt, wie bereits früher bekannt war. In dem Arctioid Clade entsprechen morphologische Gattungsgrenzen, basierend auf Blattform, Blattbedornung und Morphologie der Involukralblätter, nicht den in der molekularen analyse gefundenen clades. Es kann keine taxonomische Lösung für diesen Konflikt gefunden werden, und die gennanten Merkmale wurden als homoplastisch betrachtet. Obwohl die phylogenetische Auflösung in dem Cousinioid Clade schlecht ist, enthalten die ITS und rpS4-trnT-trnL-Sequenzen phylogenetische Information. So gruppierten z.B. die sechs annuellen Arten in zwei Gruppen. Schlechte phylogenetische Auflösung resultiert wahrscheinlich aus dem Mangel an Merkmalen und der großen Artenzahl in dieser artenreichen und vergleichsweise jungen (ca. 8,7 mya) Linie. Artbildung in dem Cousinioid Clade scheint hauptsächlich allopatrisch zu sein. Der zweite Teil der Dissertation untersucht die Rolle der Hybridisierung in der Evolution von Cousinia s.s. Die in der Vergangenheit publizierteten 28 Hybrid-Kombinationen und 11 Zwischenformen wurden kritisch geprüft, und zwei Hybridindividuen wurden morphologisch und molekular untersucht. Die vermutlichen oder nachgewiesenen Eltern der Hybriden und Zwischenformen wurden auf die aus einer Bayesischen Analyse der ITS-Sequenzen von 216 Arten von Cousinia und verwandten Gattungen resultierenden Phylogenie aufgetragen. Weder Hybriden zwischen dem Cousinioid Clade und anderen Haupt-Claden des Arctium-Cousinia-Komplexes noch zwischen annuellen und perennirenden Arten von Cousinia s.s. wurden beobachtet. Die Ergebnisse zeigen eindeutig, dass Hybridisierung in Cousinia möglich is, und dass ca. 10,7% der Arten an interspezifischer Hybridisierung beteiligt sind. Obwohl Hybridisierung in Cousinia s.s. stattfindet und zu den Schwierigkeiten bei der Rekonstruktion ihrer phylogenetischen Geschichte beitragen könnte, war ihre Rolle für die Entwicklung und Diversität der Gruppe offenbar gering. Im dritten Teil wird eine taxonomische Revision der C. sect. Cynaroideae präsentiert. Cousinia sect. Cynaroideae, die größte Sektion der Gattung mit 110 veröffentlichten Arten, zeichnet sich durch eine Chromosomenzahl von 2n = 24 und durch ± herablaufende Blätter und Hüllblätter mit Anhängseln aus. Sie kommt im Iran, Irak, dem Kaukasus, der Türkei, Turkmenistan, Afghanistan, Pakistan, dem Libanon und Anti-Libanon vor und hat ihre Hauptzentren der Artdiversität im westlichen und nordwestlichen Iran, im Irak und in der südöstlichen Türkei. Die Revision dieser Gruppe, hauptsächlich basierend auf der Untersuchung von ca. 2250 Herbarbögen, führte zu einer Verringerung der Artenzahl auf 31 Arten mit acht Unterarten. Alle Arten werden typifiziert und ausgeschlüsselt, und Beschreibungen, Abbildungen und Verbreitungskarten werden für jede Art angegeben.
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ZUSAMMENFASSUNG Die vorgelegte Dissertation enthält zwei Teile. Der erste beinhaltet eine Einführung in die Flora Südostasiens und die Untersuchungsgruppe Asteraceae-Senecioneae Cass. mit den Gattungen Cissampelopsis (DC.) Miq., Gynura Cass. und Crassocephalum Moench (Kapitel 1). Der zweite Teil besteht aus drei Manuskripten, die auf originalen Forschungsergebnissen basieren (Kapitel 2-4). In Kapitel 2 wird eine Revision der asiatischen Gattung Cissampelopsis vorgelegt. Die folgenden zwei Sektionen mit zehn Arten und zwei Varietäten werden anerkannt: sect. Buimalia C. Jeffrey & Y. L. Chen mit C. buimalia (Buch.-Ham. ex D. Don) C. Jeffrey & Y. L. Chen, C. erythrochaeta C. Jeffrey & Y. L. Chen und C. calcadensis (Ramasw.) C. Jeffrey & Y. L. Chen sowie sect. Cissampelopsis mit C. glandulosa C. Jeffrey & Y. L. Chen, C. walkeri (Arn.) C. Jeffrey & Y. L. Chen mit var. walkeri und var. floccosa Vanijajiva & Kadereit (var. nov.), C. corifolia C. Jeffrey & Y. L. Chen, C. volubilis (Bl.) Miq, C. ansteadii (Tadul. & Jacob) C. Jeffrey & Y. L. Chen, C. spelaeicola (Van.) C. Jeffrey & Y. L. Chen und C. corymbosa (Wall. ex DC.) C. Jeffrey & Y. L. Chen. Schlüssel, Artbeschreibungen, Fotographien von Blütenmerkmalen und Verbreitungskarten werden präsentiert. Kapitel 3 beinhaltet die Revision der paläotropischen Gattung Gynura. Vierundvierzig Arten werden anerkannt, darunter die folgenden drei Neubeschreibungen: G. davisii Vanijajiva & Kadereit, G. siamensis Vanijajiva & Kadereit und G. villosus Vanijajiva & Kadereit. Gynura dissecta (F. G. Davies) Vanijajiva & Kadereit, G. annua (F. G. Davies) Vanijajiva & Kadereit und G. aurantiaca (Bl) DC. subsp. parviflora (F. G. Davies) Vanijajiva & Kadereit sind Neukombinationen. Ein Schlüssel, Artbeschreibungen und Verbreitungskarten werden vorgelegt. In Kapitel 4 wird eine Analyse von Crassocephalum in Asien, einer aus Afrika eingeschleppten Gattung, präsentiert. Diese Untersuchung basiert auf umfangreicher Feldarbeit, Herbarstudien, Analysen der Pollen- und Samenfertilität, Chromosomenzählungen sowie ITS- und trnL-F-Sequenzen. Die Studie ergab, dass Crassocephalum in Asien mit zwei Arten und deren Hybrid vertreten ist. Die zwei Arten sind C. crepidioides (Benth.) S. Moore und C. rubens (Juss. ex Jacq.) S. Moore, wobei letztere einen Neufund für Asien darstellt. Der Hybrid aus diesen beiden Arten resultiert aus einer Kreuzung von C. crepidioides (2n=40) als weiblichem und C. rubens (2n=40) als männlichem Elter.
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Hintergrund: Biogeographische Verbindungen der Alpen nach Asien wurden schon im 19. Jahrhundert durch floristische Vergleiche entdeckt. Ziele: In den vorliegenden drei Artikeln wird untersucht, ob diese Verbindung entlang einer nördlichen, arktisch-borealen Route oder entlang einer südlichen Route über dazwischen liegende Gebirge wie den Kaukasus bestand. Methoden: Molekulare Phylogenien von Epimedium (Berberidaceae) und der Tribus der Hyoscyameae (Solanaceae), deren Vertreter disjunkt in den Alpen, dem Kaukasus und in asiatischen Gebirgen vorkommen, wurden mit nukleären und plastidären Markern erstellt und bio¬geographisch ausgewertet. Zur Datierung der Diversifizierungsereignisse und Arealbil¬dung diente eine molekulare Uhr. Ein aktueller floristischer Vergleich von Gattungen, die in den Alpen, den asiatischen Gebirgen und in Gebieten entlang der potentiellen Routen vor¬kom¬men, wurde unternommen und ausgewertet. Daran anschließend wurde nach molekular-phylogenetischer Literatur für interessante Gruppen aus diesem Ver¬gleich recherchiert, um diese biogeogra¬phisch bezüglich der Fragestellung zu interpretieren. Ergebnisse: Von 429 Gattungen, die in den Alpen und im Himalaya vorkommen, wachsen 218 entlang der nördlichen und der südlichen Route. 203 kommen nur entlang der süd¬lichen und drei nur entlang der nördlichen Route vor. Fünf kommen nur in den Alpen und im Himalaya vor. Epimedium, Scopolia/Physochlaina aus den Hyoscyameae und Primula sect. Auricula sind Beispiele für eine nördliche biogeographische Verbindung zwischen den Alpen und Asien. Diese bestand zumindest in den ersten beiden Fällen wahrscheinlich aus einem durchgängigen Laubwaldgürtel, der durch das abkühlende und trockener werdende Klima im Pliozän und Pleistozän fragmentiert wurde und heute nicht mehr besteht. Es handelt sich also um ein Vikarianzmuster und weniger um eine Migrationsroute. Die größere Diver¬sität dieser Guppen, die in Asien beobachtet werden kann ist sekundär entstanden. Atropa aus den Hyoscyameae, Brachypodium, die Subtribus Loliinae aus den Poaceae, Bupleurum und Doronicum sind Beispiele für eine südliche Verbindung. Hier liegen die Diversitätszentren im Mediterraneum und die Vorkommen im Osten sind abgeleitet. Schlussfolgerungen: Die Datengrundlage aus der Literaturrecherche ist nicht sehr breit und die meisten Phylogenien waren für die Fragestellung nicht aussagekräftig. Die histori¬schen Erkenntnisse und die Ideen über den Zusammenhang der Alpenflora mit der asiatischer Gebirge werden grundsätzlich bestärkt. Die Flora der Alpen enthält ein Element das über eine nördliche Verbindung noch lange mit asiatischen Gebirgen in Kontakt stand und ein südliches Element, das aus dem Mittelmeer¬raum bzw. aus SW Asien stammt. Die Beispiele für eine nördliche Verbindung sprechen allerdings nicht für eine Migration von Asien nach Europa sondern zeigen ein Vikarianzmuster auf.
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Aim: Previous studies revealed that diversification events in the western clade of the alpine Primula sect. Auricula were concentrated in the Quaternary cold periods. This implies that allopatric speciation in isolated glacial refugia was the most common mode of speciation. In the first part of the present dissertation, this hypothesis is further investigated by locating refugial areas of two sister species, Primula marginata & P. latifolia during the last glacial maximum, 21,000 years ago. In the second part, the glacial and postglacial history of P. hirsuta and P. daonensis is investigated. Location: European Alps. Methods: Glacial refugia were located using species distribution models, which are projected to last glacial maximum climate. These refugia are validated with geographic distribution patterns of intra-specific genetic diversity, rarity and variation. Results 1) Speciation: Glacial refugia of the sister taxa Primula marginata and P. latifolia were largely separated, only a small overlapping zone at the southern margin of the former glacier in the Maritime Alps exists. This overlapping zone is too small to indicate sympatric speciation. The largely separated glacial distribution of both species rather confirms our hypothesis of allopatric speciation in isolated glacial refugia. Results 2) Glacial and postglacial history: Surprizingly, the modelled potential refugia of three out of four Primula species are situated within the former ice-shield, except for P. marginata. This indicates that peripheral and central nunataks played an important role for the glacial survival in P. latifolia, P. hirsuta and P. daonensis, while peripheral refugia outside the maximum extend of the glacier were crucial in P. marginata. In P. hirsuta and P. latifolia SDMs allowed to exclude several hypothetical refugial areas that overlap with today’s distribution as potential refugia for the species. In P. marginata, hypothetical refugial areas at the periphery of the former ice-shield that overlap with today’s distribution were confirmed by the models. The results from the SDMs are confirmed by population genetic patterns in three out of four species. P. daonensis represents an exception, where population genetic data contradict the SDMs. Main conclusions: Species distribution models provide species specific scenarios of glacial distribution and postglacial re-colonization, which can be validated using population genetic analyses. This combined approach is useful and helps to understand the complex processes that have lead to the genetic and floristic patterns of biodiversity that is found today in the Alps.
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The decline of traditional religions in Japan in the past century, and especially since the end of World War Two, has led to an explosion of so-called “new religions” (shin shūkyō 新宗教), many of which have made forays into the political realm. The best known—and most controversial—example of a “political” new religion is Sōka Gakkai 創価学会, a lay Buddhist movement originally associated with the Nichiren sect that in the 1960s gave birth to a new political party, Komeitō 公明党 (lit., Clean Government Party), which in the past several decades has emerged as the third most popular party in Japan (as New Komeitō). Since the 1980s, Japan has also seen the emergence of so-called “new, new religions” (shin shin shūkyō 新新宗教), which tend to be more technologically savvy and less socially concerned (and, in the eyes of critics, more akin to “cults” than the earlier new religions). One new, new religion known as Kōfuku-no-Kagaku 幸福の科学 (lit., Institute for Research in Human Happiness or simply Happy Science), founded in 1986 by Ōkawa Ryūho 大川隆法, has very recently developed its own political party, Kōfuku Jitsugentō 幸福実現党 (The Realization of Happiness Party). This article will analyse the political ideals of Kōfuku Jitsugentō in relation to its religious teachings, in an attempt to situate the movement within the broader tradition of religio-political syncretism in Japan. In particular, it will examine the recent “manifesto” of Kōfuku Jitsugentō in relation to those of New Komeitō and “secular” political parties such as the Liberal Democratic Party (Jimintō 自民党) and the Democratic Party (Minshutō 民主党).
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INTRODUCTION: Osteoporosis is not only responsible for an increased number of metaphyseal and spinal fractures but it also complicates their treatment. To prevent the initial loosening, we developed a new implant with an enlarged implant/bone interface based on the concept of perforated, hollow cylinders. We evaluated whether osseointegration of a hollow cylinder based implant takes place in normal or osteoporotic bone of sheep under functional loading conditions during anterior stabilization of the lumbar spine. MATERIALS AND METHODS: Osseointegration of the cylinders and status of the fused segments (ventral corpectomy, replacement with iliac strut, and fixation with testing implant) were investigated in six osteoporotic (age 6.9 +/- 0.8 years, mean body weight 61.1 +/- 5.2 kg) and seven control sheep (age 6.1 +/- 0.2 years, mean body weight 64.9 +/- 5.7 kg). Osteoporosis was introduced using a combination protocol of ovariectomy, high-dose prednisone, calcium and phosphor reduced diet and movement restriction. Osseointegration was quantified using fluorescence and conventional histology; fusion status was determined using biomechanical testing of the stabilized segment in a six-degree-of-freedom loading device as well as with radiological and histological staging. RESULTS: Intact bone trabeculae were found in 70% of all perforations without differences between the two groups (P = 0.26). Inside the cylinders, bone volume/total volume was significantly higher than in the control vertebra (50 +/- 16 vs. 28 +/- 13%) of the same animal (P<0.01), but significantly less (P<0.01) than in the near surrounding (60 +/- 21%). After biomechanical testing as described in Sect. "Materials and methods", seven spines (three healthy and four osteoporotic) were classified as completely fused and six (four healthy and two osteoporotic) as not fused after a 4-month observation time. All endplates were bridged with intact trabeculae in the histological slices. CONCLUSIONS: The high number of perforations, filled with intact trabeculae, indicates an adequate fixation; bridging trabeculae between adjacent endplates and tricortical iliac struts in all vertebrae indicates that the anchorage is adequate to promote fusion in this animal model, even in the osteoporotic sheep.
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RATIONALE AND OBJECTIVES: The aim of this study was to measure the radiation dose of dual-energy and single-energy multidetector computed tomographic (CT) imaging using adult liver, renal, and aortic imaging protocols. MATERIALS AND METHODS: Dual-energy CT (DECT) imaging was performed on a conventional 64-detector CT scanner using a software upgrade (Volume Dual Energy) at tube voltages of 140 and 80 kVp (with tube currents of 385 and 675 mA, respectively), with a 0.8-second gantry revolution time in axial mode. Parameters for single-energy CT (SECT) imaging were a tube voltage of 140 kVp, a tube current of 385 mA, a 0.5-second gantry revolution time, helical mode, and pitch of 1.375:1. The volume CT dose index (CTDI(vol)) value displayed on the console for each scan was recorded. Organ doses were measured using metal oxide semiconductor field-effect transistor technology. Effective dose was calculated as the sum of 20 organ doses multiplied by a weighting factor found in International Commission on Radiological Protection Publication 60. Radiation dose saving with virtual noncontrast imaging reconstruction was also determined. RESULTS: The CTDI(vol) values were 49.4 mGy for DECT imaging and 16.2 mGy for SECT imaging. Effective dose ranged from 22.5 to 36.4 mSv for DECT imaging and from 9.4 to 13.8 mSv for SECT imaging. Virtual noncontrast imaging reconstruction reduced the total effective dose of multiphase DECT imaging by 19% to 28%. CONCLUSION: Using the current Volume Dual Energy software, radiation doses with DECT imaging were higher than those with SECT imaging. Substantial radiation dose savings are possible with DECT imaging if virtual noncontrast imaging reconstruction replaces precontrast imaging.
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The aim of this study was to assess the potential of monoenergetic computed tomography (CT) images to reduce beam hardening artifacts in comparison to standard CT images of dental restoration on dental post-mortem CT (PMCT). Thirty human decedents (15 male, 58 ± 22 years) with dental restorations were examined using standard single-energy CT (SECT) and dual-energy CT (DECT). DECT data were used to generate monoenergetic CT images, reflecting the X-ray attenuation at energy levels of 64, 69, 88 keV, and at an individually adjusted optimal energy level called OPTkeV. Artifact reduction and image quality of SECT and monoenergetic CT were assessed objectively and subjectively by two blinded readers. Subjectively, beam artifacts decreased visibly in 28/30 cases after monoenergetic CT reconstruction. Inter- and intra-reader agreement was good (k = 0.72, and k = 0.73 respectively). Beam hardening artifacts decreased significantly with increasing monoenergies (repeated-measures ANOVA p < 0.001). Artifact reduction was greatest on monoenergetic CT images at OPTkeV. Mean OPTkeV was 108 ± 17 keV. OPTkeV yielded the lowest difference between CT numbers of streak artifacts and reference tissues (-163 HU). Monoenergetic CT reconstructions significantly reduce beam hardening artifacts from dental restorations and improve image quality of post-mortem dental CT.
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OBJECTIVE The objective of this study was to assess the discriminative power of dual-energy computed tomography (DECT) versus single-energy CT (SECT) to distinguish between ferromagnetic and non-ferromagnetic ballistic projectiles to improve safety regarding magnetic resonance (MR) imaging studies in patients with retained projectiles. MATERIALS AND METHODS Twenty-seven ballistic projectiles including 25 bullets (diameter, 3-15 mm) and 2 shotgun pellets (2 mm each) were examined in an anthropomorphic chest phantom using 128-section dual-source CT. Data acquisition was performed with tube voltages set at 80, 100, 120, and 140 kV(p). Two readers independently assessed CT numbers of the projectile's core on images reconstructed with an extended CT scale. Dual-energy indices (DEIs) were calculated from both 80-/140-kV(p) and 100-/140-kV(p) pairs; receiver operating characteristics curves were fitted to assess ferromagnetic properties by means of CT numbers and DEI. RESULTS Nine (33%) of the projectiles were ferromagnetic; 18 were nonferromagnetic (67%). Interreader and intrareader correlations of CT number measurements were excellent (intraclass correlation coefficients, >0.906; P<0.001). The DEI calculated from both 80/140 and 100/140 kV(p) were significantly (P<0.05) different between the ferromagnetic and non-ferromagnetic projectiles. The area under the curve (AUC) was 0.75 and 0.8 for the tube voltage pairs of 80/140 and 100/140 kV(p) (P<0.05; 95% confidence interval, 0.57-0.94 and 0.62-0.97, respectively) to differentiate between the ferromagnetic and non-ferromagnetic ballistic projectiles; which increased to 0.83 and 0.85 when shotgun pellets were excluded from the analysis. The AUC for SECT was 0.69 and 0.73 (80 and 100 kV[p], respectively). CONCLUSIONS Measurements of DECT combined with an extended CT scale allow for the discrimination of projectiles with non-ferromagnetic from those with ferromagnetic properties in an anthropomorphic chest phantom with a higher AUC compared with SECT. This study indicates that DECT may have the potential to contribute to MR safety and allow for MR imaging of patients with retained projectiles. However, further studies are necessary before this concept may be used to triage clinical patients before MR.