bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fatigue damage analysis in a duplex stainless steel by digital image correlation technique
Authors: EL BARTALI A. , AUBIN V. , DEGALLAIX S. 
Published: March 2008

ABSTRACTStrain field measurements by digital image correlation today offer new possibilities for analysing the mechanical behaviour of materials in situ during mechanical tests. The originality of the present study is to use this technique on the micro‐structural scale, in order to understand and to obtain quantitative values of the fatigue surface damage in a two‐phased alloy. In this paper, low‐cycle fatigue damage micromechanisms in an austenitic‐ferritic stainless steel are studied. Surface damage is observed in real time, with an in situ microscopic device, during a low‐cycle fatigue test performed at room temperature. Surface displacement and strain fields are calculated using digital image correlation from images taken during cycling. A detailed analysis of optical images and strain fields measured enables us to follow precisely the evolution of surface strain fields and the damage micromechanisms. Firstly, strain heterogeneities are observed in austenitic grains. Initially, the austenitic phase accommodates the cyclic plastic strain and is then followed by the ferritic phase. Microcrack initiation takes place at the ferrite/ferrite grain boundaries. Microcracks propagate to the neighbouring austenitic grains following the slip markings. Displacement and strain gradients indicate probable microcrack initiation sites.
Fractographic reconstitution of fatigue crack history – Part I
Authors: NEDBAL I. , SIEGL J. , KUNZ J. , LAUSCHMANN H. 
Published: March 2008

ABSTRACTQuantitative fractography of components which have failed under cyclic loading can offer very valuable information usually unattainable by any other means – in particular, a detailed description of fatigue crack growth (FCG) in space and in time. The reliable characterization of crack propagation provides data important in engineering applications. The main source of information on the relationship between fractographic findings and macroscopic crack growth rate (CGR) is striation spacing. This quantitative microfractographic characteristic was the basis for the methods described in the paper. An application of the fractographic reconstitution of FCG is illustrated by an example of an aircraft wing spar fatigued during a full‐scale test.
Fractographic reconstitution of fatigue crack history – Part II
Authors: NEDBAL I. , LAUSCHMANN H. , SIEGL J. , KUNZ J. 
Published: March 2008

ABSTRACTThe most valuable quantitative information contained in fatigue fracture surfaces is related to striations. An alternative source of information, in particular if striation identification is impossible, can be the general characteristics of fracture micromorphology evaluated by digital image analysis. For study of micrographs as image textures, new methods called textural fractography have been developed. In this paper, some of these methods and examples of their application are described. A generalization for the case of a variable cycle loading is proposed, based on a new concept of counting loading cycles. The presented work foreshadows the potential contribution of textural fractography for fractographic reconstitution of fatigue crack history.
Influence of through‐thickness crack shape on plasticity induced crack closure
Authors: BRANCO R. , RODRIGUES D. M. , ANTUNES F. V. 
Published: March 2008

ABSTRACTIn most of the previous three‐dimensional (3D) numerical studies of plasticity induced crack closure (PICC), ideal shapes have been assumed for the cracks. The aim of present paper is to study the effect of crack shape on PICC. With this objective a 3D numerical model was developed to predict PICC in middle‐tension (MT) specimens with different thicknesses and crack shapes. The radial size of crack tip elements and the stabilization of closure level were studied to ensure the quality of numerical predictions. Simultaneously, an independent numerical model was developed to predict crack shape evolution, stable crack shapes and corresponding K distributions. Crack closure was found to produce a significant tunnelling effect, with maximum values of ΔK and Kmax at the surface. The curved crack presented significant plastic deformation near the free surface which has a high impact on the computation time, compared to the straight crack. The modification of ΔK and Kmax with crack shape produced a variation of 38% in opening values at the interior positions, but relatively small variations at the surface. Considering the great influence of crack shape on PICC, it is fundamental to model realistic crack shapes.
Imagery or meaning? Evidence for a semantic origin of category‐specific brain activity in metabolic imaging
Authors: Hauk Olaf , Davis Matthew H. , Kherif Ferath , Pulvermüller Friedemann 
Published: March 2008

AbstractCategory‐specific brain activation distinguishing between semantic word types has imposed challenges on theories of semantic representations and processes. However, existing metabolic imaging data are still ambiguous about whether these category‐specific activations reflect processes involved in accessing the semantic representation of the stimuli, or secondary processes such as deliberate mental imagery. Further information about the response characteristics of category‐specific activation is still required. Our study for the first time investigated the differential impact of word frequency on functional magnetic resonance imaging (fMRI) responses to action‐related words and visually related words, respectively. First, we corroborated previous results showing that action‐relatedness modulates neural responses in action‐related areas, while word imageability modulates activation in object processing areas. Second, we provide novel results showing that activation negatively correlated with word frequency in the left fusiform gyrus was specific for visually related words, while in the left middle temporal gyrus word frequency effects emerged only for action‐related words. Following the dominant view in the literature that effects of word frequency mainly reflect access to lexico‐semantic information, we suggest that category‐specific brain activation reflects distributed neuronal ensembles, which ground language and concepts in perception‐action systems of the human brain. Our approach can be applied to any event‐related data using single‐stimulus presentation, and allows a detailed characterization of the functional role of category‐specific activation patterns.
Role for the NR2B subunit of the N‐methyl‐d‐aspartate receptor in mediating light input to the circadian system
Authors: Wang L. M. , Schroeder A. , Loh D. , Smith D. , Lin K. , Han J. H. , Michel S. , Hummer D. L. , Ehlen J. C. , Albers H. E. , Colwell C. S. 
Published: March 2008

AbstractLight information reaches the suprachiasmatic nucleus (SCN) through a subpopulation of retinal ganglion cells that utilize glutamate as a neurotransmitter. A variety of evidence suggests that the release of glutamate then activates N‐methyl‐d‐aspartate (NMDA) receptors within the SCN and triggers a signaling cascade that ultimately leads to phase shifts in the circadian system. In this study, we first sought to explore the role of the NR2B subunit in mediating the effects of light on the circadian system of hamsters and mice. We found that localized microinjection of the NR2B subunit antagonist ifenprodil into the SCN region reduces the magnitude of light‐induced phase shifts of the circadian rhythm in wheel‐running activity. Next, we found that the NR2B message and levels of phospho‐NR2B vary with time of day in SCN tissue using semiquantitative real‐time polymerase chain reaction and western blot analysis, respectively. Functionally, we found that blocking the NR2B subunit with ifenprodil significantly reduced the magnitude of NMDA currents recorded in SCN neurons. Ifenprodil also significantly reduced the magnitude of NMDA‐induced Ca2+ changes in SCN cells. Together, these results demonstrate that the NR2B subunit is an important component of NMDA receptor‐mediated responses within SCN neurons and that this subunit contributes to light‐induced phase shifts of the mammalian circadian system.
Sacrococcygeal pilonidal disease
Authors: Lee P. J. , Raniga S. , Biyani D. K. , Watson A. J. M. , Faragher I. G. , Frizelle F. A. 
Published: March 2008

AbstractBackground  Sacrococcygeal pilonidal is a common disease in active young adults. Many surgical methods have been proposed, although no clear consensus as to the optimal treatment has been reported. This review looks at the different surgical techniques available and examines the reported results of primary healing, recurrent disease and complications (including delayed healing).Method  A literature search using the Medline database was performed to locate English language articles on surgery for pilonidal disease. Further articles were obtained from the references cited in the literature initially reviewed.Results  Management should be tailored according to the individual and whether the disease is acute or chronic. Treatment should take into consideration hospital stay and return to work. Simple excision, curettage, partial lateral wall excision, or marsupialisation, are simple techniques with good results. They can be used for the initial surgery but their use is not recommended for recurrent disease. The modified rhomboid flap for recurrent disease has consistently shown positive results in terms of complication rates and recurrence.Conclusion  We would recommend tailored treatment with simple excision for initial presentation and the modified rhomboid flap for recurrent disease.
Phylogenetic comparison of spicule networks in cryptobranchiate dorid nudibranchs (Gastropoda, Euthyneura, Nudibranchia, Doridina)
Authors: Penney Brian K. 
Published: March 2008

AbstractMany dorid nudibranchs possess large numbers of calcareous spicules in their mantle, gill, rhinophores and foot. However, the arrangements of these structures and their differences among taxa are poorly known. Spicule networks were stained with Alizarin red and compared among 12 species of cryptobranchiate dorid nudibranchs and four outgroups. Three general types of networks were found: a cobweb‐like, unbraced framework of one or few spicules per side; a ramifying system of thick, spiculated tracts; and a lattice‐like arrangement of distinct radial and circumferential tracts. The Discodorididae species investigated shared a cobweb‐like network and papillae supported by a ring of spicules, while the Porostomata showed consistent characters leading to a lattice‐like network with larger spicules in the central notum. The Dorididae studied were not cohesive, but each species shared characters with the aforementioned groups. Therefore, spicule network form may provide new characters to help resolve the phylogeny of Doridina.
Induced thermotolerance and tissue Hsc70 in juvenile coho salmon, Oncorhynchus kisutch
Authors: Arkush Kristen D. , Cherr Gary N. , Clegg James S. 
Published: March 2008

AbstractWe examined Hsc70 in gill, liver and caudal fin from coho salmon (Oncorhynchus kisutch) before (ambient, ~12 °C) and after a sublethal heat shock of 25 °C for 1 h. Increased levels were observed for at least 48 h in all three tissues. Attempts to demonstrate isoforms of this heat‐shock protein were not successful using four different antibodies. However, one of these antibodies recognized isoforms in brine shrimp and oysters, two organisms in which the heat‐shock response has been well characterized. Extracts of those organisms and coho salmon tissues were run on the same gels and evaluated on the same Western blots, at the same time. We believe that our results provide a reliable account of Hsc70 in these fish under these conditions. Limited experiments showed that induced thermotolerance was achieved in these coho salmon, lasting for about 1 week after the sublethal heat shock. These data suggest that increased levels of Hsc70 are correlated with induced thermotolerance in these fish.
Why are so many boreal freshwater fishes anadromous? Confronting ‘conventional wisdom’
Authors: McDowall Robert M 
Published: March 2008

AbstractSuggestions that anadromy predominates in northern high latitudes because boreal marine seas have high primary productivity are questioned. Instead, post‐Pleistocene invasion of far northern fresh waters, which became inhabitable as Pleistocene temperatures ameliorated, via coastal seas, is suggested as a primary cause for northern distributions of widely anadromous fish families. Also, cold temperature preferences may be implicated in determining the ranges of these families, as well as the inhospitability of far northern fresh waters and the lack of ecosystem space to support the huge populations of boreal anadromous fishes. Moreover, there are significant numbers of tropical anadromous fish species.
Structure, Agency and Power in Political Analysis: Beyond Contextualised Self-Interpretations
Authors: Glynos Jason , Howarth David 
Published: March 2008

This article evaluates Mark Bevir and Rod Rhodes’ interpretive approach to political analysis by examining their account of social change. Their work is significant because they have endeavoured to construct a distinctive approach which strikes a productive balance between philosophical reflection and analytical attention to the empirical domain. Moreover, in elaborating their approach, Bevir and Rhodes wage a war along a number of fronts: positivism, institutionalism and post-structuralism, and so an analysis of their work enables us to take stock of a range of contemporary methods and approaches. In considering their underlying presuppositions and commitments, we pay particular attention to their account of human agency and its relationship to social structures and political power. While we agree with much of their critique of positivism, naturalism, realism and institutionalism, we argue that Bevir and Rhodes risk overplaying the role of interpreting the individual beliefs and desires of relevant actors to the detriment of a wider net of social practices and logics. Moreover, in challenging their understanding of the post-structuralist approach to political analysis we develop its resources to enrich the possibilities of a critical interpretivism, moving beyond concepts like tradition, dilemma and situated agency. Put more precisely, we argue that the radical contingency of social structures and human agency – their structural incompleteness – discloses new ways of understanding both their character and their mutual intertwining. For example, we develop the categories of lack, dislocation and political identification to think human agency and its relation to wider social structures. More broadly, we argue that an approach developed around different sorts of logics – social, political and fantasmatic – goes some way to steering a different course between a pure thick descriptivism that focuses principally on individual beliefs and desires on the one hand, and a concern with causal laws and mechanisms on the other.
REPRODUCTIVE PHENOLOGY OFLAMINARIA SACCHARINA(L.) LAMOUR. (PHAEOPHYTA) AT THE SOUTHERN LIMIT OF ITS DISTRIBUTION IN THE NOTHWESTERN ATLANTIC OCEAN1,2
Authors: Lee Jin‐Ae , Brinkhuis Boudewijn H. 
Published: March 2008

ABSTRACTLaminaria saccharina(L) Lamour. Sporophytes were monitored monthly from October 1982 to September 1983 to investigate reproduction phenology and relationshiops to growth paatterns aaat its southern limit of distribution in the northwest Atlantic Ocean (Long Island Soundd). Plants exhibited an annual growth pattern. Growth raate, bladelehgth, maximum width, area, stiipe lehgth an wet weight swhoed the same seasonal pattern and reached maximum values between May and June. Only blade thickness continued to increase tthrooughout the ovservation period. Blade dissintegration occurred dduring August and September.Reproductive sporophytes occurred throughout the observation period; the greatest frequency of appearance occurred in October (43.8%) and June (37.8%). The blade area covered by sori ranged from 2.4% (Janaury) to 6.1% (August). Meiospore release under laboratory conditions was maximum in May and minimum in July. No meio‐spores were released in August Sporulation was not correlated with meristematic growth of nitrogen content How ever, reproductive plants were generally larger and thicker throughout the sporulation period, and had a greater carbort content is spring than nonreproductive plants. Fecundity and reproductive success of female gametophytes were maximum in spring and minimum in winter. The growth of early sporophyte stages in the laboratory was greatest in early spring; however, juvenile macroscopic stages were hardly observed in the field during summer months due to warm water temperatures. “Over‐summering” of gamelophytes and / or microscopic sporophytes may account for the annual cycle ofLaminariaat its southern limit of distribution.
DISTRIBUTION, MORPHOLOGICAL DIVERSITY AND EVIDENCE FOR POLYPLOIDY IN NORTH AMERICAN ZYGNEMATACEAE (CHLOROPHYTA)1
Authors: McCourt Richard M. , Hoshaw Robert W. , Wang Jen‐Chyong 
Published: March 2008

ABSTRACTLarge‐scale collections of Zygnemataceae in the continental United States of America were made between March and August in 1982, 1983, and 1984. Collections were made on a 31000‐km transect through 35 states. Zygnemataceae were found at 318 sites was inspected. Temperature average 19°C and pH averaged 6.1 over all sites. Algal strains in collections were identified to genus, characterized for filament width, chloroplast number, and end wall type, then photographed and isolated into unialgal culture. Spirogyra was the most common genus collected(632 strains), followed in abundance by Zygnema (174 Strains) and Mougeotia (135 strains). These three genera contained 95% of the strains collected and were equally widely distributed. Strains of the three genera frequently occurred together; no genus displayed evidence of habitat specialization among the three habitat types: flowing water, permanent ponds or lakes, and temporary pools. In Spirogyra, strains with plane (flat) end walls were four times more abundant than those with replicate (interlocking) end walls. Spirogyra with plane end walls showed more variation in filament width than Zygnema, Mougeotia, or Spirogyra with replicate end walls. In Spirogyra with plane end walls, filament width was correlted with nuclear DNA content and number of strains found per collection site was twice that of other genera or Spirogyra, with replicate end walls. Spirogyra strains wider than 70 μm were more frequent on the northern part of the transect. It is proposed that polyploidy may be of widespread occurrence in Spirogyra with plane end walls and that associated morphological plasticity may account for the high apparent specied diversity and survival of the genus in a wider variety of microhabitats than occupied by other Zygnemataceae.
THE INLAND CHAETOCEROS (BACILLARIOPHYCEAE) SPECIES OF NORTH AMERICA1
Authors: Rushforth Samuel R. , Johansen Jeffrey R. 
Published: March 2008

ABSTRACT Five taxa of Chaetoceros occur in inland waters of North America. These most commonly occur in waters with elevated total dissolved solids in arid regions of the western United States and Canada. Chaetoceros amanita Cleve‐Euler is characterized by consistently forming relatively long chains of cells and having very spinose primary resting spore valves. Chaetoceros elmorei Boyer also forms long chains of cells which are connected by evident valvar processes; spores are nearly always smooth. Chaetoceros muelleri Lemm. may form short chains with processes between sibling valves, but also produces solitary cells lacking processes. Chaetoceros muelleri var. subsalsum (Lemm.)Johansen et Rushforth is similar to the nominate but never produces cells with Processes. Both of the C. muelleri varieties produce spores with smooth primary valves. Chaetoceros simplex Ostenfeld is characterized by a noncolonial habit, cells lacking processes and the production of resting spores with warty to some what spinose primary valves.
AN INVESTIGATION OF THE CELL WALL COMPONENTS OF ACTINOCYCLUS SUBTILIS (BACILLARIOPHYCEAE)1
Authors: Andersen H. A. , Medlin L. K. , Crawford R. M. 
Published: March 2008

ABSTRACT The frustule of Actinocyclus subtilis (Greg.) Ralfs has been examined in detail with light and electron microscopy. The complex valve structure can only he appreciated fully by means of thin‐sections. The loculate areola is closed to the inside by a basket of organic material, which is supported by a system of radiating, lightly silicified ribs. The basket is easily destroyed by acid cleaning, thus leaving an open hole (foramen). The loculus is connected to the outside by a system of interconnecting channels, whose external openings are too small to be resolved by the SEM. Between the locules of the valve face is a complex system of bullulae. The labiate processes are slightly tilted from the vertical axis vis à vis the valve mantle. Fibrillar material and mucilage are present within each labiate process, observations not reported previously. Histochemistry indicates that acid mucopolysaccharides are present within the lumen of the labiate process. We propose that the secretion of mucilage is related to the rotational, but directed movement noted in this centric diatom. The pseudonodulus is a solid silica plate subtended on the inside by a disc of organic material external to the cytoplasm. The relationship between Actinocyclus, Hemidiscus, Roperia, Charcotia and Azpeitia is discussed based on these new findings of valve morphology. Also the relationship between the families Hemidiscaceae and Coscinodiscaceae is discussed.
THE OCCURRENCE AND STRUCTURE OF FLAGELLAR SCALES IN SOME FRESHWATER CRYPTOPHYTES1
Authors: Lee Robert Edward , Kugrens Paul 
Published: March 2008

ABSTRACT Flagellar scales were found in seven out of eleven fresh‐water cryptophytes investigated by shadowing whole cells. All scales examined were 140 to 170 nm in diameter and had a basic seven‐sided rosette pattern with delicate interlacing. The results of this study indicate that flagellar scales are common in cryptophytes.
ULTRASTRUCTURE OF THE CARPOSPOROPHYTE AND CARPOSPOROGENESIS IN THE PARASITIC RED ALGA PLOCAMIOCOLAX PULVINATA SETCH, (GIGARTINALES, PLOCAMIACEAE) 1
Authors: Kugrens Paul , Delivopoulos Stylianos G. 
Published: March 2008

ABSTRACT The ultrastructure of the carposporophyte and carposporogenesis is described for the parasitic red alga Plocamiocolax pulvinata Setch. After presumed fertilization the zygote nucleus is apparently transferred to the auxiliary cell which initiates gonimoblast cell production. These gonimoblast cells differentiate into storage or generative cells. Storage gonimoblast cells (SGC) are large and multinucleate, contain large quantities of starch and are located nearest the auxiliary cell, when compared to the smaller uninucleate, devoid of starch, generative gonimoblast cells (GGC) that form terminal lobes of carpospores. In addition, compressed membrane bodies and annulate lamellae are common in these cells. During carposporophyte maturation the amount of starch in the SGC's decreases and eventually the auxiliary cell, as well as SGC's, degenerate. Generative gonimoblast cells (GGC's) cleave repeatedly to form carpospores which are interconnected by small pit connections. Stage one‐carpospores are recognized by their elongated shape, the formation of small