bluuebunny/crossref_metadata_2025 huggingface dataset:
Importance of site conditions and time since abandonment for coppice vegetation on Langeland, Denmark
Authors: Petersen Peter Milan
Published: March 2008

In 57 sample plots in neglected coppices on Langeland, Denmark (14—c. 125 years since last coppicing) the cover of trees and shrubs was analysed by the method of Domin‐Krajina and the ground layer by the frequency method of Raunkiær. The data were analysed by DC A. The tree and shrub layer showed significant correlations with topsoil pH and litter depth. The ground layer was significantly correlated with inclination, area of the wood in which the coppice was situated, light, topsoil pH and the tree layer, and to a lesser extent with litter depth, but was not correlated with time since last coppicing. It is suggested that for some stands the suppression of Corγlus avellana by tree species (Quercus robur, Fagus sylvatica, Carpinus betulus) which form a permanent litter layer and acidify the soil is more important to the ground layer than the time elapsed since last coppicing per se. Formation of a permanent litter layer reduces species density, e‐specially of some forest species without clonal growth. One main reason for the lack of correlation between the ground layer and time since coppicing may be the great environmental variation in the neglected coppices on Langeland. Another reason seems to be the absence of competitive forest species (which otherwise would benefit from non‐intervention) due to the isolated position of the coppiced woods. It is concluded that neglect in excess of c. 35 years beyond the normal coppice rotation has some effect on the composition of the tree and shrub layer, but not a direct effect on the ground layer.
Post‐fire regeneration strategies and tree bark resistance to heating in frequently burning tropical savanna woodlands and grasslands in Ethiopia
Authors: Gashaw Menassie , Michelsen A. , Friis I. , Jensen M. , Demissew Sebsebe , Woldu Zerihun
Published: March 2008

Regeneration mechanisms of vegetation and the role of tree bark resistance to frequent fire were studied in savanna woodlands and grasslands in Gambella, Western Ethiopia. Data were collected from four sites, each with three replicate plots. The variation between sites in species composition and biomass correlated with the differences in fire intensity. Foliar cover was recorded for individual plant species regenerating by sprouting from older parts of plants that had survived fire or by seedlings; records were made during the dry season and at the beginning of the wet season. Data on bark thickness and tree diameters of 12 dominant tree species were also recorded. Both facultative and obligate sprouters significantly contributed to post‐fire recovery, comprising 98.5 % of total vegetation cover. The contribution of seedlings to cover and abundance immediately following fire was negligible, but seedling density increased in the beginning of the rainy season, 4 to 5 months after fire. The importance of the sprouting and seeding strategies varied between the different plant growth forms. The highest contribution to cover and frequency was made by the most abundant grass species, which reproduced in both ways. Facultative sprouters made up 67.3 % of the vegetation cover, out of which 54 % consisted of grasses. Broad‐leaved herbs and trees/shrubs regenerating mainly by sprouting made up 31.3 % of the vegetation cover. Adaptations to fire in tree species seemed to include the development of a thick bark, once the tree has passed seedling stages. Tree bark thickness and tree diameter at breast height were strongly correlated with the time taken for cambium to reach an assumed lethal temperature of 60°C when exposed to fire, which indicated that mature trees with thick barks might resist stronger fire better than, e.g., small or young trees and trees with thin bark. However, for a given bark thickness the cambium resistance to heat varied three‐fold among species. Hence, site differences in fire intensity seemed to influence the distribution of trees depending on their bark characteristics and resistance to fire.
The identity of Boesenbergia acuminata (Zingiberaceae)
Authors: Larsen Kai
Published: March 2008

Boesenbergia acuminata is shown to be synonymous with B. ochroleuca.
A new species of Spermacoce (Rubiaceae) from the Manika high plateau (Katanga; R. D. Congo)
Authors: Dessein S. , Jansen S. , Robbrecht E. , Smets E.
Published: March 2008

Spermacoce manikensis, a new species from Katanga (R. D. Congo) is described and illustrated. Special attention is given to anatomy of the primary root and pollen and seed morphology. The species is mainly characterised by the geoxylic habit, large flowers arranged in two‐or three‐flowered inflorescences, and seeds with a basal elaiosome. It is closely related to Spermacoce stipularis, from which it differs in its more robust taproot and habit, longer leaves, larger fruits, and 10–13(‐14)‐ aperturate pollen grains. The species is found on the Kalahari sands of the Manika high plateau in suffrutex grassland.
Four new species and one new record of Lasianthus (Rubiaceae) from Thailand
Authors: Hua Zhu
Published: March 2008

Four new species of the genus Lasianthus are described from Thailand and accompanied with taxonomic remarks. These new taxa are: L. ellipsoideus, L. flavi‐hirtus, L. loeiensis and L roosianus. One variety, L. politus var. insularis is considered to be a synonym of L. coronatus extending the range of this species to Thailand.
The taxonomic value of fruit structure in the Chinese endemic genus Dickinsia (Apiaceae)
Authors: Liu M. , van Wyk B‐E. , Tilney P. M.
Published: March 2008

The monotypic Dickinsia Franch. is misplaced in its current position in the tribe Hydrocotyleae and is transferred to the tribe Mulineae. Its mericarps are strongly dorsally compressed and the lateral ribs of each mericarp are much more prominent than the dorsal rib. The carpophore is free. These characters are typical for genera of the Mulineae but are obviously different from other genera of Hydrocotyleae, which all have laterally compressed mericarps, dorsal ribs which are more expanded than the lateral ribs and an absence of free carpophores.
On the identity of Macrotheca elaeocarpa (Olacaceae)
Authors: Malécot Valéry
Published: March 2008

A taxon, named Macrotheca elaeocarpa belongs, according to Fagerlind, to tribe Couleae of Olacaceae (Santalales). However this name was never published, and never mentioned by taxonomists working on the Olacaceae family. A study of material available from Swedish Museum of Natural History shows that specimens called Macrotheca elaeocarpa Dusén in this herbarium belong to the South American Tetrastylidium grandifolium, and are the southern most occurrence of this species. However, drawing and description in Fagerlind's work do not agree with this identification. As all material is lacking flowers, it is possible that embryological studies have been based on other misidentified material from one of the three Couleae genera: Coula, Minquartia and Ochanostachys.
Two new species of Acalypha (Euphorbiaceae) from Peru
Authors: Cardiel José Maria
Published: March 2008

Two new species of the genus Acalypha are described and illustrated., A. salicina and A. simplicistyla, based on Peruvian material. Comments on the systematics of related species are included.
Two new species of Caloplaca from Tadjikistan, Central Asia
Authors: Kondratyuk Sergey , Kärnefelt Ingvar , Kudratov Imomnazar , Khodosovtsev Alexander
Published: March 2008

Two new species of Caloplaca are described, C. pseudocitrina (in the C. citrina group), which is characterized by rather long spores with a thin septum, and a squamulose thallus and C. akbarica (C. saxicola‐growp) characterized by rather thick, brightly yellowish pruinose apothecia and a parapiectenchymatous proper exciple. The characters of the new species and their closely allied taxa are compared in tables and illustrated.
Species composition and vegetation structure of an upper montane forest at the summit of Mt. Doi Inthanon, Thailand
Authors: Khamyong Soontorn , Lykke Anne Mette , Seramethakun Dusit , Barfod Anders S.
Published: March 2008

Upper montane forest (UMF) within Doi Inthanon National Park, Northern Thailand, was investigated by means of fifty, 40 × 40 m stratified random plots situated between 2080 and 2565 m altitude. The aim was to address a number of community ecological questions concerning woody species composition and structural heterogeneity of the forest. A total of 7474 individuals of trees and woody climbers ≥ 15 cm gbh (girth at breast height) were included in the study and these were identified to 47 species, 39 genera and 26 families. The average density was 934 individuals/ha and the average stem basal area was 71.8 m2/ha. The most important species were: Quercus eumorpha, Sjzygium angkae, Litsea martabanica, Helicia nilagirica, Lindera caudata, Schima wallichii, Osmanthus fiagrans, Eurya acuminata, Myrsine semiserrata and Ilex umbellulata and the most important families were Fagaceae, Lauraceae, Theaceae and Myrtaceae. Altitude was the most important environmental variable explaining species composition and vegetation structure. Most of the calculated vegetation variables showed significant correlation with altitude: species richness, family richness, diversity, density and crown cover declined with altitude, average tree height was uncorrelated with altitude and basal area increased with altitude. An analysis of size class distributions indicated good forest conditions and reverse‐J‐shaped age class distribution of most species.
Modelling the distribution of Ilex aquifolium at the north‐eastem edge of its geographical range
Authors: Bañuelos María José , Kollmann Johannes , Hartvig Per , Quevedo Mario
Published: March 2008

Plant distribution borders are key features to characterise the ecological niche of a species and to monitor effects of climate change. Here we focus on an evergreen small tree, Ilex aquifolium, which reaches its north‐eastern range edge in Denmark. Our main objectives are to describe and to model the current distribution of the species, to identify the most important climatic and land use factors which shape this distribution pattern, and to analyse the species' habitat requirements. For this purpose we used data from a national mapping project, complemented by information from forest owners. The distribution and abundance of I. aquifolium in Denmark have markedly changed during the past 40 years. It is now found in almost all districts, although the centres of abundance still coincide with the historical records. Our model shows lower habitat suitability for the species in northern and eastern districts, where winters are more severe and spring precipitation is lower. To a lesser extent, land use influences I. aquifolium occurrence, but it is more common in areas with a high proportion of forests and/or urban sites. The analysis of habitat requirements supports these results, since I. aquifolium occurs mainly as a forest species in deciduous stands, on relatively nutrient‐rich moist soils, and under moderately high light conditions. However, some records may be the product of seed dispersal from planted individuals nearby. The results suggest that the range edge of the species has moved at least 100 km east within half a century. Since I.aquifolium is sensitive to winter frost, this change in distribution may be due to increasingly mild winter temperatures.
An outline of the genus Geigeria (Asteraceae, Inuleae)
Authors: Ortiz S.
Published: March 2008

We present a synopsis of the genus Geigeria (Inuleae, Asteraceae). Particular attention is paid to the taxonomic characterization and phylogenetic relationships of the genus, to possible supraspecific groupings, and to the delimitation of taxa, especially at the infraspecific level. Until recently 25 species, 20 subspecies, and 7 varieties have been recognized. In this study we recognize only 20 species, 12 subspecies, and 7 varieties. We describe a new subspecies and variety, and propose 5 new nomenclatural combinations.
Two ways of trapping seeds in alpine environments, Lapland, Sweden
Authors: Larsson Eva‐Lena
Published: March 2008

Seed dispersal in two habitats was investigated in the mid‐alpine Latnjajaure valley, in northernmost Swedish Lapland. The seed rain size was measured using artificial seed traps and natural snowbed at a heath and a meadow site, c. 1000 m a.s.l. The average seed rain size trapped in the snowbeds varied from 18 seeds m‐2 at the heath site, to 96 seeds m‐2 at the meadow site. On average, the heath trap station had 177 seeds m‐2 and the meadow station, 218 seeds m2. At each site, the vegetation was inventoried within a circular area with a radius of 20 m. Overall, the species assembly in the seed rain reflected the surrounding vegetation. However, there were additional species in the seed rain as well. At the seed trap station on the wind‐exposed heath, 78% of the seeds originated from sites outside the homogeneous vegetation around the trap. These seeds were dispersed from locations at least 150 m from the trap site. By trapping a higher number of species than artificial traps and a higher number of seeds per unit area, snowbeds served as effective ‘seed traps’. However, the location of the sampling spot in the snowbed is crucial due to a decrease in seed density towards the edge. In this study, with the aim of trapping the main dispersing species in the area, the optimal artificial seed trap size appears to be ‐ 1.5–2.0 m2. There was also a positive correlation between the mean July and August temperature, the seed rain size, and the number of species found. Thus, through brief visits to remote locations, the study of seed dispersal can be accomplished effectively when snowbeds are present on the landscape.
Floral morphology and anatomy of Pittosporum tobira (Pittosporaceae)
Authors: Zhou Qingyuan , Fu Dezhi , Jin Xiaobai
Published: March 2008

Comparative studies are made on floral morphology and anatomy of female and male flowers of Pittosporum tobira. The two types of flower differ little from each other in structure at the early stage of floral development, but appear dimorphic towards anthesis. The male flower becomes cryptically bisexual, although its pistil is slender compared to that of the female flower. The stigmas of the male flower are receptive and can induce pollen germination. The structure of the style in the male flower is identical to that in the female flower. Ovules are produced on the protruded parietal placenta in the male flower, but their development is arrested at the stage of the 4–nucleate embryo sac. The female flower is clearly unisexual, with obviously aborted and sagittate anthers. Its pistil is rather plump and can produce darkish red seeds immersed in sticky pulp. The male and female flowers are similar in vascular anatomy. A conspicuous difference between the two types of flower lies in the stamens. Variation of sexual organs in the genus Pittosporum is reviewed. We assume that the flowers of Pittosporum are derived from the hermaphrodite‐flowered ancestor and the female flower has become unisexual through partial reduction of sexual organs at a faster rate than the male flower.
Further studies in the genus Caulokaempferia (Zingiberaceae) in Thailand with the description of two new species
Authors: Larsen Kai , Suksathan Piyakaset , Triboun Pramote
Published: March 2008

Two new species of Caulokempferia from Thailand, C. amplexicaule and C. pedemontana are described and illustrated. The biogeography and the diversity of the genus are discussed.
A new species of Minuartia (Caryophyllaceae) from the island of Evvia (Greece)
Authors: Trigas Panayiotis , Iatroú Gregoris
Published: March 2008

Minuartia dirphya from Mt Dirphys (Evvia) is described as a species new to science. It is closely related to M. wettsteinii from Mt Thriptis (East Kriti) and M. parnonia from Mt Pamon (South Peloponnisos). The three narrow endemic species form a well‐defined group, the Minuartia wettsteinii‐group, within Minuartia ser. Laricifoliae Mc Neill. Additions to the descriptions, chorological and ecological data for M. wettsteinii and M. parnonia are provided. The morphological characters of the group and the differences to the other species of ser. Laricifoliae are discussed. A key to the species, illustrations of the taxa and their seeds, chromosome numbers and data on their geographical distribution are also provided.
A new Cephalaria species (Dipsacaceae) from the European part of Turkey
Authors: Kuş Semra , Göktürk R. Süleyman
Published: March 2008

A new species, Cephalaria tuteliana, (Dipsacaceae) from the European part of Turkey is described and illustrated. The characteristics of the new species, and its relationships with Cephalaria tenuiloba is discussed.
Studies in African Cyperaceae 29. Scleria afroreflexa, a new species from western Cameroon
Authors: Lye Kåre Arnstein , Pollard Benedict John
Published: March 2008

A new rare species, Scleria afroreflexa. is descriped from an upland area (1500 m) of South west Cameroon. It is most similar to S. sheilae Rayn., another rare species only known from one collection from a rocky habitat at 800 m near Yaounde in southeastern Cameroon. S. afroreflexa differs, however, in its more dense inflorescence with reflexed branches, its more hairy leaves, smaller achenes and in its montane habitat. Notes on habitat, ecology, distribution and conservation are given for the two species.
Trichomanes vamana, a new filmy fern species (Hymenophyllaceae ‐ Pteridophyta) from India
Authors: Hameed C. Abdul , Madhusoodanan P. V.
Published: March 2008

Trichomanes vamana, a new species of filmy fern from South India is described and illustrated. Key to South Indian species of Trichomanes subg. Didymoglossum sect. Microgonium and affinities of this taxon with T.mindorense are discussed
Seasonal pattern of dry matter allocation in Dactylorhiza lapponica (Orchidaceae) and the relation between tuber size and flowering
Authors: Øien Dag‐Inge , Pedersen Bård
Published: March 2008

A population of the tuberous orchid Dactylorhiza lapponica was sampled from June 2000 to June 2001 in the Sølendet Nature Reserve, Central Norway. Dry matter of aerial shoots, old tubers and new (replacement) tubers was measured, as well as reproductive status during 1999–2001. The biomass of the new tuber was found to continue to increase after the assimilation from photosynthesis had ceased in August. It is suggested that the increase is caused by mycotrophic activity and reallocation of nutrients from the aerial shoots. There was a clear relationship between tuber size and flowering behaviour. Individuals with flower primordia had the largest replacement tuber, whereas those that flowered in the sampling season or remained vegetative throughout 1999–2001 had the smallest. Individuals that flowered in the sampling season had the largest old tuber. Those, which had not flowered for at least two years, but had developed flower primordia, had the second largest, and those that remained vegetative throughout 1999–2001 had the smallest one. Individuals with a replacement tuber less than 0.22 g in October, have a very low probability of flowering the following season. Flowering entails a cost in terms of reduced biomass of the replacement tuber compared to vegetative individuals with old tubers of similar size. Allometric analyses revealed that above‐ground biomass and biomass of replacement tubers increased with the biomass of old tubers in vegetative individuals. For generative individuals, however, above‐ground biomass was only weakly related to below‐ground biomass.
Phylogeny of cryptogrammoid ferns and related taxa based on rbcL sequences
Authors: Zhang Gangmin , Zhang Xianchun , Chen Zhiduan
Published: March 2008

Cryptogrammoid ferns were often classified into the cheilanthoid group (of Pteridaceae sensu Tryon et al.) or Sinopteridaceae sensu Ching. In order to elucidate the phylogenetic relationships of cryptogrammoid ferns and their related taxa, we sequenced the chloroplast rbcL gene for 11 Asian species representing Cryptogramma, Onychium, Aleuritopteris, Leptolepidium, Cheilosoria, and Doryopteris. Sequences of other related groups were obtained from GenBank. Phylogenetic analysis of a data matrix including 32 taxa was conducted using the maximum‐parsimony (MP) and neighbor‐joining (NJ) methods. The results were as follows: (1) Cryptogramma, Coniogramme, and Llavea form a moderately supported clade and constitute a cryptogrammoid group that is distantly related to the cheilanthoid ferns. (2) Onychium is rejected from both the cheilanthoid and the cryptogrammoid group, but closely related to Actiniopteris and Pteris. (3) The cheilanthoid group is monophyletic, which is supported by a high bootstrap value. It comprises most of the genera in Sinopteridaceae sensu Ching and some genera in Hemionitidaceae sensu Pichi Sermolli. (4) In the cheilanthoid group, several genera from the Old World (including Aleuritopteris, Leptolepidiurn, Cheilosoria, and Sinopteris), which have been subsumed into Cheilanthes by some authors, are grouped together and distantly related to the American taxa of Cheilanthes. The present study supports the treatment of the cryptogrammoids as either a separate family or subfamily of a broadly circumscribed Pteridaceae, but Pichi Sermolli's circumscription of Cryptogrammaceae should be emended to include Coniogramme and to exclude Onychium.
Ornithogalum mekselinae (Liliaceae), a new species from southwestern Anatolia, Turkey
Authors: Varol Ömer
Published: March 2008

Ornithogalum mekselinae is described from the Muðla‐Yaral, (C2:Mubla province) in Turkey. It is related to Ornithogalum sigmoideum, from which it mainly differs in its bulb with bulbils, 8–12 flowers, the lenght of perianth segments that are very conspicuously 6–ribbed.
A new species of Eugenia (Myrtaceae) from the Western Ghats, India
Authors: Murugan C. , Gopalan R.
Published: March 2008

Eugenia shettyana, is described and illustrated as a new species from the Western Ghats, India. The differences to similar taxa are discussed.
Alyssum mughlaei (Brassicaceae), a new species from Southwest Anatolia
Authors: Orcan Nermin
Published: March 2008

Alyssum mughlaei (Brassicaceae) is a new species, described and illustrated from Southwest Anatolia, Turkey.
Taxonomic notes on European taxa of Crataegus (Rosaceae)
Authors: Christensen Knud lb , Janjic Nikola
Published: March 2008

In connection with systematic study of European taxa of Crataegus (Rosaceae subfam. Maloideae) lectotypes are designated for Crataegus monogyna f. subdigyna and C. monogyna var. ronnigeri. C. microphylla subsp. malýana is described as a taxon new to science and a key to the recognised taxa of C. microphylla and of the closely related C. rhipidophylla is given.
The distribution and origins of Faúopia × bohemica (Polygonaceae) in Europe
Authors: Bailey John , Wisskirchen Rolf
Published: March 2008

Faúopia×bohemica is a good example of a hybrid occurring when two introduced species come in contact in their adventive range. Although only recognised in the early 1980's, herbarium material and the current distribution pattern suggest that it has long been an unrecognised part of the Japanese Knotweed s.l. population. The identification, distribution, cytological background, history and some of the ecological determinants of the spread in Europe are provided along with a substantial citation of field observations and herbarium specimens used to produce the distribution map. This is the first attempt to map its European distribution, and must be regarded as provisional since comprehensive recording of its distribution is limited to a handful of countries. The unexpected discovery for the first time of this taxon in the Mediterranean is also reported. It is to be hoped that this paper will provide the impetus for a more comprehensive study of this invidious and under‐recorded taxon.
Lithocarpus glaucus, a new species of Fagaceae from China
Authors: Ye Huagu , Wang Faguo , Ye Yushi
Published: March 2008

Lithocarpus glaucus (Fagaceae) is described and illustrated. L. glaucus resembles L. hancei, but can easily be distinguished by its bigger leaves, glabrous inflorescence rachis and the cupule only covering the base of the nut.
Typification of names in Cyperus section Arenarii (Cyperaceae)
Authors: Väre Henry , Kukkonen Ilkka
Published: March 2008

The typification of names in the genus Cyperus was done as part of an ongoing study of the section Arenarii. The latest monograph on the genus by Kükenthal (1936), accepted eight species in the section Bobartia (=Arenarii), and a number of lower level taxa, which are treated here either as distinct species or synonyms. The taxonomic treatment of the core species, C. conglomerates Rottb., turned out to be especially confusing, which is reflected in the past identifications of the material, and consequently, has created wrong interpretations on the distributions. C. jeminicus Rottb. has similarly caused a lot of confusion. Currently we recognize 26 species in the section, with two subspecies in C. conglomerate. Most names in the section have not earlier been typified. Here we designate lectotypes for 33 names, three epitypes, and one neotype. Cyperus sections Arenarii Kunth and Hymenolepides Nees are typified also.
Expansion of Crabbea (Acanthaceae) and the description of two new species from Somalia
Authors: Thulin Mats
Published: March 2008

Crabbea is expanded to include the monotypic Golaea and Acanthostelma, both endemic in northern Somalia. The new combinations C. migiurtina (=Golaea migiurtina) and C. thymifolia (=Acanthostelma thymifolium) are made and the names are lectotypified. The new species C. pinnatifida and C. albolutea, both endemic in Somalia, are described and illustrated.
A new species of Atriplex (Chenopodiaceae) from Somalia
Authors: Thulin Mats
Published: March 2008

Atriplex erigavoensis, a new species from gypsum silt in northern Somalia, is described and illustrated. It is distinctive particularly by the dorsal appendages of the female bracteoles that look like an extra pair of small bracteoles.
Taxonomic notes on Astragalus sect. Malacothrix (Fabaceae) from Iran
Authors: Ranjbar M.
Published: March 2008

Astragalus porphyrogrammus, occurring in the Zarin‐Abad of Zanjan (Iran), is described and illustrated. This species belongs to A. sect. Malacothrix and seems to be distinct and interesting among the Iranian species. In this research, A. sect. Grammocalyx which was very artificial placed in A. subgen. Calycophysa transferred to A. subgen. Hypoglottis. Moreover, relationships between A. subgen. Hypoglottis and the closely related subgenera in genus Astragalus are discussed. Also A. lineatus is recorded for Iran.
Genetic variation and biogeography of Mertensia maritima (Boraginaceae)
Authors: Skarpaas Olav , Elven Reidar , Nordal Inger
Published: March 2008

To elucidate the population dynamics and biogeographic connections of Mertensia maritima in the North Atlantic we studied the genetic variation within and among 16 local populations in the Oslofjord region (south‐east Norway), Finnmark (northern Norway), Iceland and Svalbard, using starch gel isozyme electrophoresis. We also tested the self‐compatibility experimentally. Mertensia maritima was found to be self‐compatible and able to self‐pollinate by autodeposition. The total level of genetic variation was extremely low. All the screened individuals were homozygous at all loci. All individuals from the populations of mainland Norway and Iceland were isozymatically identical, whereas individuals from Svalbard differed from these at three loci (AAT‐1, PGM‐3 and SKD‐2). The genetic identity between any population at Svalbard and any population on the mainland was 0.86. These genetic patterns may have resulted from a combination of inbreeding, frequent local population extinctions, and long‐distance dispersal. The isozymatic distinctness of the Svalbard populations is consistent with the arctic distribution of the morphologically based var. tenella, here raised to subspecific rank as Mertensia maritima ssp. tenella.
Flow Control of Annular Compressor Cascade by Synthetic Jets
Authors: Zheng Xinqian , Zhou Sheng , Lu Yajun , Hou Anping , Li Qiushi
Published: March 2008

An experimental investigation conducted in a stationary annular cascade wind tunnel demonstrated that unsteady flow control using synthetic jets (zero mass flux) could effectively reduce flow separation in the axial compressor cascade. The synthetic jets driven by speaker were introduced through the casing radially into the flow-field just adjacent to the leading edge of the compressor cascade. The experimental results revealed that the aerodynamic performance of the compressor cascade could be improved amazingly by synthetic jets and the maximum relative reduction of loss coefficient was up to 27.5%. The optimal analysis of the excitation frequency, excitation location was investigated at different incidences. In order to obtain detailed information on flow-field structure, the digital particle image velocimetry (DPIV) technique was adopted. The experimental results indicated that the intensity of wake vortices became much weaker and streamlines became smoother and more uniform with synthetic jets.
Heat Transfer at High Rotation Numbers in a Two-Pass 4:1 Aspect Ratio Rectangular Channel With 45deg Skewed Ribs
Authors: Zhou Fuguo , Acharya Sumanta
Published: March 2008

Heat transfer measurements are reported for a rotating 4:1 aspect ratio (AR) coolant passage with ribs skewed 45deg to the flow. The study covers Reynolds number (Re) in the range of 10,000–70,000, rotation number (Ro) in the range of 0–0.6, and density ratios (DR) between 0.1 and 0.2. These measurements are done in a rotating heat transfer rig utilizing segmented copper pieces that are individually heated, and thermocouples with slip rings providing the interface between the stationary and rotating frames. The results are compared with the published data obtained in a square channel with similar dimensionless rib-geometry parameters, and with the results obtained for a 4:1 AR smooth channel. As in a 1:1 AR channel, rotation enhances the heat transfer on the destabilized walls (inlet-trailing wall and outlet-leading wall), and decreases the heat transfer ratio on the stabilized walls (inlet-leading wall and outlet-trailing wall). However, the rotation-induced enhancement/degradation for the 4:1 rectangular channel is much weaker than that in the square ribbed channel, especially in the inlet (the first passage). The results on the inlet-leading wall are in contrast to that in the smooth channel with the same AR, where rotation causes heat transfer to increase along the inlet-leading wall at lower Reynolds number (Re=10,000 and 20,000). Higher DR is observed to enhance the heat transfer on both ribbed walls in the inlet (the first passage) and the outlet (the second passage), but the DR effects are considerably weaker than those in a ribbed square channel. Measurements have also been parameterized with respect to the buoyancy parameter and results show the same general trends as those with respect to the rotation number. In addition, pressure drop measurements have been made and the thermal performance factor results are presented.
The Impact of Gas Modeling in the Numerical Analysis of a Multistage Gas Turbine
Authors: Rubechini Filippo , Marconcini Michele , Arnone Andrea , Maritano Massimiliano , Cecchi Stefano
Published: March 2008

In this work a numerical investigation of a four stage heavy-duty gas turbine is presented. Fully three-dimensional, multistage, Navier-Stokes analyses are carried out to predict the overall turbine performance. Coolant injections, cavity purge flows, and leakage flows are included in the turbine modeling by means of suitable wall boundary conditions. The main objective is the evaluation of the impact of gas modeling on the prediction of the stage and turbine performance parameters. To this end, four different gas models were used: three models are based on the perfect gas assumption with different values of constant cp, and the fourth is a real gas model which accounts for thermodynamic gas properties variations with temperature and mean fuel∕air ratio distribution in the through-flow direction. For the real gas computations, a numerical model is used which is based on the use of gas property tables, and exploits a local fitting of gas data to compute thermodynamic properties. Experimental measurements are available for comparison purposes in terms of static pressure values at the inlet∕outlet of each row and total temperature at the turbine exit.
A Comparison of Approximate Versus Exact Geometrical Representations of Roughness for CFD Calculations of cf and St
Authors: Bons J. P. , McClain S. T. , Wang Z. J. , Chi X. , Shih T. I.
Published: March 2008

Skin friction (cf) and heat transfer (St) predictions were made for a turbulent boundary layer over randomly rough surfaces at Reynolds number of 1×106. The rough surfaces are scaled models of actual gas turbine blade surfaces that have experienced degradation after service. Two different approximations are used to characterize the roughness in the computational model: the discrete element model and full 3D discretization of the surface. The discrete element method considers the total aerodynamic drag on a rough surface to be the sum of shear drag on the flat part of the surface and the form drag on the individual roughness elements. The total heat transfer from a rough surface is the sum of convection on the flat part of the surface and the convection from each of the roughness elements. Correlations are used to model the roughness element drag and heat transfer, thus avoiding the complexity of gridding the irregular rough surface. The discrete element roughness representation was incorporated into a two-dimensional, finite difference boundary layer code with a mixing length turbulence model. The second prediction method employs a viscous adaptive Cartesian grid approach to fully resolve the three-dimensional roughness geometry. This significantly reduces the grid requirement compared to a structured grid. The flow prediction is made using a finite-volume Navier-Stokes solver capable of handling arbitrary grids with the Spalart-Allmaras (S‐A) turbulence model. Comparisons are made to experimentally measured values of cf and St for two unique roughness characterizations. The two methods predict cf to within ±8% and St within ±17%, the RANS code yielding slightly better agreement. In both cases, agreement with the experimental data is less favorable for the surface with larger roughness features. The RANS simulation requires a two to three order of magnitude increase in computational time compared to the DEM method and is not as readily adapted to a wide variety of roughness characterizations. The RANS simulation is capable of analyzing surfaces composed primarily of roughness valleys (rather than peaks), a feature that DEM does not have in its present formulation. Several basic assumptions employed by the discrete element model are evaluated using the 3D RANS flow predictions, namely: establishment of the midheight for application of the smooth wall boundary condition; cD and Nu relations employed for roughness elements; and flow three dimensionality over and around roughness elements.
Analytical Modeling of Turbine Cascade Leading Edge Heat Transfer Using Skin Friction and Pressure Measurements
Authors: Holley Brian M. , Langston Lee S.
Published: March 2008

The flow near the leading edge stagnation line of a plane turbine cascade airfoil is analyzed using measurements, analytical modeling, and computational fluid dynamics modeling. New measurements of skin friction and pressure are used to show that the aerodynamics of the leading edge, within what we call the stagnation region, are well described by an exact analytical solution for laminar stagnation-point or Hiemenz flow. The skin friction measurements indicate the extent of the stagnation region. The same parameters that characterize Hiemenz flow also characterize stagnation-point potential flow. The thermal resistance of the laminar momentum boundary layer in Hiemenz flow is absent in the inviscid solution. Consequently, the heat transfer in stagnation-point potential flow is greater than the heat transfer in Hiemenz flow. Based on measurements from an earlier study, the highest heat transfer levels in the cascade occur along the leading edge stagnation line. Stagnation-point potential flow provides a close, upper bound for the measured heat transfer at this small but critical location within the stagnation region. This paper describes how to apply the analytical model for predicting cascade stagnation-line heat transfer using only surface pressure calculations.
Methicillin-Resistant
Staphylococcus saprophyticus
Isolates Carrying Staphylococcal Cassette Chromosome
mec
Have Emerged in Urogenital Tract Infections
Authors: Higashide Masato , Kuroda Makoto , Omura Carlos Takashi Neves , Kumano Miyuki , Ohkawa Saburo , Ichimura Sadahiro , Ohta Toshiko
Published: March 2008

Staphylococcus saprophyticus
is a uropathogenic bacterium that causes acute uncomplicated urinary tract infections, particularly in female outpatients. We investigated the dissemination and antimicrobial susceptibilities of 101
S. saprophyticus
isolates from the genitourinary tracts of patients in Japan. Eight of these isolates were
mecA
positive and showed β-lactam resistance. Pulsed-field gel electrophoresis showed that only some isolates were isogenic, indicating that the
mecA
gene was apparently acquired independently by
mecA
-positive isolates through staphylococcal cassette chromosome
mec
(SCC
mec
). Type determination of SCC
mec
by multiplex PCR showed a nontypeable element in the eight
mecA
-positive isolates. Sequence analysis of the entire SCC
mec
element from a prototype
S. saprophyticus
strain revealed that it was nontypeable with the current SCC
mec
classification due to the novel composition of the class A
mec
gene complex (IS
431
-
mecA
-
mecR1
-
mecI
genes) and the
ccrA1/ccrB3
gene complex. Intriguingly, the attachment sites of SCC
mec
are similar to those of type I SCC
mec
in
S. aureus
NCTC 10442. Furthermore, the genes around the
mec
gene complex are similar to those of type II/III SCC
mec
in
S. aureus
, while those around the
ccr
gene complex are similar to those of SCC
15305RM
found in
S. saprophyticus
ATCC 15305. In comparison with known SCC
mec
elements, this
S. saprophyticus
SCC
mec
is a novel type.
New Anti-Infective Coatings of Medical Implants
Authors: Matl F. D. , Obermeier A. , Repmann S. , Friess W. , Stemberger A. , Kuehn K.-D.
Published: March 2008

Implantable devices are highly susceptible to infection and are therefore a major risk in surgery. The present work presents a novel strategy to prevent the formation of a biofilm on polytetrafluoroethylene (PTFE) grafts. PTFE grafts were coated with gentamicin and teicoplanin incorporated into different lipid-like carriers under aseptic conditions in a dipping process. Poly-
d
,
l
-lactic acid, tocopherol acetate, the diglyceride Softisan 649, and the triglyceride Dynasan 118 were used as drug carriers. The drug release kinetics, anti-infective characteristics, biocompatibility, and hemocompatibility of the coatings developed were studied. All coatings showed an initial drug burst, followed by a low continuous drug release over 96 h. The dimension of release kinetics depended on the carrier used. All coated prostheses reduced bacterial growth drastically over 24 h, even below pathologically relevant concentrations. Different cytotoxic levels could be observed, revealing tocopherol acetate as the most promising biocompatible carrier. A possible reason for the highly cytotoxic effect of Softisan 649 could be assessed by demonstrating incorporated lipids in the cell soma with Oil Red O staining. Tromboelastography studies, enzyme-linked immunosorbent assays, and an amidolytic substrate assay could confirm the hemocompatibility of individual coatings. The development of the biodegradable drug delivery systems described here and in vitro studies of those systems highlight the most important requirements for effective as well as compatible anti-infective coatings of PTFE grafts. Through continuous local release, high drug levels can be produced at only the targeted area and physiological bacterial proliferation can be completely inhibited, while biocompatibility as well as hemocompatibility can be ensured.
The Efflux Pump Inhibitor Reserpine Selects Multidrug-Resistant
Streptococcus pneumoniae
Strains That Overexpress the ABC Transporters PatA and PatB
Authors: Garvey Mark I. , Piddock Laura J. V.
Published: March 2008

One way to combat multidrug-resistant microorganisms is the use of efflux pump inhibitors (EPIs). Spontaneous mutants resistant to the EPI reserpine selected from
Streptococcus pneumoniae
NCTC 7465 and R6 at a frequency suggestive of a single mutational event were also multidrug resistant. No mutations in
pmrA
(which encodes the efflux protein PmrA) were detected, and the expression of
pmrA
was unaltered in all mutants. In the reserpine-resistant multidrug-resistant mutants, the overexpression of both
patA
and
patB
, which encode ABC transporters, was associated with accumulation of low concentrations of antibiotics and dyes. The addition of sodium orthovanadate, an inhibitor of ABC efflux pumps, or the insertional inactivation of either gene restored wild-type antibiotic susceptibility and wild-type levels of accumulation. Only when
patA
was insertionally inactivated were both multidrug resistance and reserpine resistance lost. Strains in which
patA
was insertionally inactivated grew significantly more slowly than the wild type. These data indicate that the overexpression of both
patA
and
patB
confers multidrug resistance in
S. pneumoniae
but that only
patA
is involved in reserpine resistance. The selection of reserpine-resistant multidrug-resistant pneumococci has implications for analogous systems in other bacteria or in cancer.
Expression, Purification, and Characterization of the Immunological Response to a 40-KilodaltonPlasmodium vivaxTryptophan-Rich Antigen
Authors: Siddiqui Asim A. , Bora Hema , Singh Neeru , Dash Aditya P. , Sharma Yagya D.
Published: March 2008

We describe here an ∼40-kDaPlasmodium vivaxtryptophan-rich antigen (PvTRAg40) which contains 321 amino acids and 11.4% tryptophan residues. This protein shows 65% homology (35% identity) with the previously described PvTRAg, besides sharing 23 of 27 positionally conserved tryptophan residues and similar genomic organization. The nucleotide sequence of the entire tryptophan-rich domain of PvTRAg40 was identical among 35P. vivaxclinical isolates. The protein is expressed by ring, trophozoite, and schizont stages of the parasite. The cDNA covering exon 2 of PvTRAg40 was cloned and expressed in the pPROEXHTa vector, and recombinant protein was purified. A high humoral immune response (90.7% seropositivity;n= 43) against this recombinant protein was detected in humans during the course of naturalP. vivaxinfection. Eighty percent of the total of 20P. vivax-exposed individuals exhibited lymphoproliferative responses against this antigen. The T cells of these individuals produced larger amounts of interleukin-12 (IL-12), IL-4, and IL-10 than gamma interferon and tumor necrosis factor alpha cytokines in response to the recombinant protein. Production of Th2-biased cytokines, conserved T- and B-cell epitopes, and an enhanced humoral immune response indicate that PvTRAg40 could possibly induce antibody-mediated immune protection against infection.
Identification of Genes Particularly Sensitive to Lipopolysaccharide (LPS) in Human Monocytes Induced by Wild-Type versus LPS-DeficientNeisseria meningitidisStrains
Authors: Øvstebø Reidun , Olstad Ole Kristoffer , Brusletto Berit , Møller Anne Sophie , Aase Audun , Haug Kari Bente Foss , Brandtzaeg Petter , Kierulf Peter
Published: March 2008

Lipopolysaccharide (LPS) in the outer membrane ofNeisseria meningitidisplays a dominant role as an inflammation-inducing molecule in meningococcal disease. We have used microarray analysis to study the global gene expression after exposure of human monocytes for 3 h to wild-typeN. meningitidis(106), LPS-deficientN. meningitidis(106and 108), and purifiedN. meningitidisLPS (1 ng [33 endotoxin units]/ml) to identify LPS-inducible genes. Wild-typeN. meningitidis(106) induced 4,689 differentially expressed genes, compared with 72 differentially expressed genes induced by 106LPS-deficientN. meningitidisorganisms. However, 108LPS-deficientN. meningitidisorganisms induced 3,905 genes, indicating a dose-response behavior of non-LPS cell wall molecules. A comparison of the gene expression patterns from 106wild-typeN. meningitidisand 108LPS-deficientN. meningitidisorganisms showed that 2,401 genes in human monocytes were not strictly LPS dependent. A list of “particularly LPS-sensitive” genes (2,288), differentially induced by 106wild-typeN. meningitidisbut not by 108LPS-deficientN. meningitidisorganisms, showed an early expression of beta interferon (IFN-β), most likely through the Toll-like receptor-MyD88-independent pathway. Subsequently, IFN-β may activate the type I IFN signaling pathway, and an unknown number of IFN-β-inducible genes, such as those for CXCL9, CXCL10, CXCL11, IFIT1, IFIT2, IFIT3, and IFIT5, are transcribed. Supporting this, human monocytes secreted significantly higher levels of CXCL10 and CXCL11 when stimulated by 106wild-typeN. meningitidisorganisms than when stimulated by 108LPS-deficientN. meningitidisorganisms. Plasma CXCL10, but not CXCL11, was positively correlated (r= 0.67;P< 0.01) to LPS in patients (n= 24) with systemic meningococcal disease. Thus, new circulating biomarkers in meningococcal disease may be suggested through LPS-induced gene expression changes in human monocytes.
A MODULAR IMPLEMENTATION OF DATA STRUCTURES IN BULK-SYNCHRONOUS PARALLEL ML
Authors: GAVA FRÉDÉRIC
Published: March 2008

A functional data-parallel language called BSML has been designed for programming Bulk-Synchronous Parallel algorithms. Many sequential algorithms do not have parallel counterparts and many non-computer science researchers do not want to deal with parallel programming. In sequential programming environments, common data structures are often provided through reusable libraries to simplify the development of applications. A parallel representation of such data structures is thus a solution for writing parallel programs without suffering from disadvantages of all the features of a parallel language. In this paper we describe a modular implementation in BSML of some data structures and show how those data types can address the needs of many potential users of parallel machines who have so far been deterred by the complexity of parallelizing code.
ON IMPLEMENTING THE FARM SKELETON
Authors: POLDNER MICHAEL , KUCHEN HERBERT
Published: March 2008

Algorithmic skeletons intend to simplify parallel programming by providing a higher level of abstraction compared to the usual message passing. Task and data parallel skeletons can be distinguished. In the present paper, we will consider several approaches to implement one of the most classical task parallel skeletons, namely the farm, and compare them w.r.t. scalability, overhead, potential bottlenecks, and load balancing. We will also investigate several communication modes for the implementation of skeletons. Based on experimental results, the advantages and disadvantages of the different approaches are shown. Moreover, we will show how to terminate the system of processes properly.