bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effectiveness of hand and rotary instrumentation for removing a new synthetic polymer‐based root canal obturation material (Epiphany) during retreatment
Authors: Schirrmeister J. F. , Meyer K. M. , Hermanns P. , Altenburger M. J. , Wrbas K.‐T. 
Published: February 2006

AbstractAim  To evaluate the effectiveness of hand and rotary instrumentation for removal of vertically compacted Epiphany and gutta‐percha during retreatment.Methodology  Sixty extracted single‐rooted maxillary central incisors were enlarged to size 40 using FlexMaster instruments. The teeth were randomly divided into four groups of 15 specimens each. The canals of two groups were obturated using vertically compacted Epiphany. The others were filled with vertically compacted gutta‐percha and AH Plus sealer. One Epiphany group and one gutta‐percha group was reinstrumented with Gates Glidden burs and Hedström files. In the other two groups, obturation material was removed using Gates Glidden burs and RaCe rotary instruments. After clearing the roots, the area of remaining obturation material on the root canal wall was measured using a computer image analysis program. Statistical analysis was performed using Repeated Measures Analysis of Variance and anova.Results  Retreatment of specimens obturated with gutta‐percha showed significantly more remaining obturation material than specimens filled with Epiphany (P < 0.05). No difference was found between the removal with Hedström files and with RaCe instruments (P > 0.05). Regarding the mean time of retreatment and time required for reaching the working length, Hedström files were significantly faster than RaCe instruments (P < 0.05). The times did not depend on the kind of obturation material (P > 0.05).Conclusions  Vertically compacted Epiphany in combination with Epiphany Root Canal Sealant was removed more effectively than gutta‐percha and AH Plus sealer. Hedström files were more rapid than RaCe rotary instruments.
Palatal mucosa necrosis because of accidental sodium hypochlorite injection instead of anaesthetic solution
Authors: Gursoy U. K. , Bostancı V. , Kosger H. H. 
Published: February 2006

AbstractAim  A case is reported in which sodium hypochlorite (NaOCl) was inadvertently injected into the palatal mucosa instead of local anaesthetic solution.Summary  An adult male was referred to the University clinic 15 days after an inadvertent NaOCl injection into the palatal mucosa. Soft tissue necrosis was evident, without obvious bony involvement. Tissues healed without scarring within 30 days. No surgical intervention was required.Key learning points  • NaOCl is highly irritant when extruded into vital tissues• Dentists should be careful to avoid the misuse of NaOCl, and should check the nature of any agent before injecting it into patients• NaOCl should not be dispensed in a way that could allow it to be mistaken for local anaesthetic solutions• The well‐perfused tissues of the oral cavity have considerable healing ability
C‐shaped root canal in a maxillary first molar: a case report
Authors: Yılmaz Z. , Tuncel B. , Serper A. , Calt S. 
Published: February 2006

AbstractAim  This case report presents an unusual C‐shaped root canal system in a maxillary first molar tooth.Summary  Although C‐shaped root canals are most frequently seen in the mandibular second molar, they may also appear in maxillary molars. A literature search revealed only a few case reports of C‐shaped root canal systems in maxillary molars. The present case describes a C‐shaped canal in the buccal root of a maxillary first molar. The endodontic access cavity displayed two canal orifices, one leading to the canal system in the buccal root, the other into the palatal root canal system. In the buccal root, what appeared to be the mesial and distal canals joined to form a single C‐shaped canal.Key learning points  • Careful examination of radiographs and the internal anatomy of teeth is essential.• The location and morphology of root canals should be identified at high magnification under the microscope.
The Influence of Flowing Water on the Resource Pursuit‐Risk Avoidance Tradeoff in the CrayfishOrconectes virilis
Authors: Pecor Keith W. , Hazlett Brian A. 
Published: February 2006

AbstractThe influence of hydrodynamics on chemically mediated behavioral tradeoffs has received little attention. We tested the hypothesis that individuals of the crayfishOrconectes viriliswould be more sensitive to chemical cues in flowing water than in still water.Orconectes virilisis a good subject for this test, because it is found in both still water (e.g. ponds), and flowing water (e.g. rivers). A factorial design was used, with two stimulus treatments and two habitat types. Crayfish were exposed to either food cue or food + alarm cue in either still water or flowing water in an artificial stream arena. Habitat use and activity were significantly influenced by stimulus treatment, with more time spent away from the stimulus source and less activity in the food + alarm treatment than in the food treatment. Neither habitat type nor the interaction of stimulus treatment and habitat type had a significant effect on the response variables. Given the natural history ofO. virilis, we suggest that selection has favored the ability to equally utilize chemical cues in both still and flowing water. We acknowledge that different flow conditions may influence chemical ecology in this species and caution against the view that tests in flowing waters necessarily provide a more accurate approximation of natural responses.
Life History Effects Upon Contest Behaviour: Age as a Predictor of Territorial Contest Dynamics in Two Populations of the Speckled Wood Butterfly, Pararge aegeria L.
Authors: Kemp Darrell J. , Wiklund Christer , Gotthard Karl 
Published: February 2006

AbstractAlthough empirical studies of life history effects upon sexually selected phenomena have largely overlooked contest behaviour, recent research suggests that territorial contest participation in butterflies may be mediated by ageing per se. Verbal and mathematical arguments predict lifetime increases in the expression of risky male reproductive behaviours, such as fighting, under a range of ecological conditions. Here we explored the relevance of ageing per se to contest dynamics in two phenologically distinct populations of the speckled wood butterfly, Pararge aegeria. We established 160 experimental like‐population contests among naïve south Swedish and Madeiran dyads, 112 of which we varied the age difference between combatants by 3–4 d. Although this age asymmetry did not influence contest outcome in either population, we found weak positive covariance between the loser's age and contest duration amongst Madeiran males. This is consistent with a slight lifetime increase in aggression because the duration of these aerial persistence contests is a sensitive measure of the losing male's level of aggressive intent. However, the size of this effect (semi‐partial correlation = 0.281) suggests age is not as strongly relevant to contest behaviour in P. aegeria as in other territorial butterflies. We discuss the ways in which ecological differences between butterfly species, particularly with respect to predation risk, may have influenced the evolution of lifetime aggressive strategies in this group.
Do I Know You? Species Recognition Operates Within and Between the Sexes in a Unisexual–Bisexual Species Complex of Mollies
Authors: Gumm J. M. , Gonzalez R. , Aspbury A. S. , Gabor C. R. 
Published: February 2006

AbstractMale sailfin mollies (Poecilia latipinna) can be sexually parasitized by closely related, unisexual, gynogenetic Amazon mollies (Poecilia formosa). This study examined possible cues used by male P. latipinna to distinguish between conspecific females and sympatric, heterospecific P. formosa. Digital photos were used to create models to test male P. latipinna preference for model female P. latipinna and P. formosa with a full suite of traits and altered models of P. latipinna and P. formosa. Male P. latipinna significantly preferred models of either species over no stimulus, demonstrating that models elicit a male response. Males also significantly preferred female P. latipinna models over P. formosa models. We also examined species recognition by female sailfin mollies using the same models, and found that female sailfin mollies significantly preferred to associate with female P. latipinna over P. formosa. These results taken together suggest that the use of fish models yield results similar to those studies using live stimuli. Male preference was then tested for unaltered vs. altered models in the following combinations: (i) P. formosa vs. P. formosa with a female P. latipinna fin; (ii) P. formosa vs. P. formosa with a female P. latipinna lateral spot pattern; (iii) P. formosa vs. P. latipinna with a P. formosa fin and their spotless lateral pattern. Males did not significantly prefer models with any isolated traits over the unaltered P. formosa models. Thus, males may be using traits other than the ones isolated for species recognition or males may be using a suite of multiple traits to recognize conspecific females.
Firefly Courtship: Behavioral and Morphological Predictors of Male Mating Success in Photinus greeni
Authors: Demary Kristian , Michaelidis Constantinos I. , Lewis Sara M. 
Published: February 2006

AbstractDifferences in male mating success can generate selection on male morphological traits and courtship behaviors involved in male–male competition or female mate choice. In Photinus fireflies (Coleoptera: Lampyridae), courtship is based on bioluminescent flash signals produced by both sexes. We conducted field observations of Photinus greeni fireflies engaged in competitive courtships, in which females are able to simultaneously assess several males, to identify male morphological traits and courtship behaviors that might predict male mating success. Male morphological traits did not differ between males that successfully mated compared with unsuccessful males (dialoging males that did not mate). However, courtship behavioral interactions differed: successful males tended to have higher flash pattern rates (number of flash patterns per minute), and their courtship flashes were more likely to be answered by females. We also examined how the risk of predation by Photuris fireflies altered courtship behavior of their Photinus prey. When predatory Photuris fireflies were present, P. greeni females were less likely to mate, and showed decreased flash responses to most males. However, P. greeni males that did successfully mate in spite of Photuris presence were males that maintained high flash pattern rates that elicited female responses. These results suggest that both female mate choice and Photuris predation exert strong selective pressures on the evolution of courtship signals in Photinus fireflies.
Nest Sanitation in Social Spider Mites: Interspecific Differences in Defecation Behavior
Authors: Sato Yukie , Saito Yutaka 
Published: February 2006

AbstractNest sanitation behavior is an important adaptation in nest‐building animals. The social spider mite Stigmaeopsis miscanthi (Saito) constructs woven nests on the leaf undersurface of perennial pampas grass (Miscanthus sinensis Anderss) and lives in the nests in large groups. Nest members of this species defecate at only one site inside the nest for nest sanitation, and the waste management is maintained by volatile chemical and tactile cues. Other members of the genus Stigmaeopsis Banks also construct woven nests, live in groups, and manage their fecal wastes, but the species differ in nest and group size, host plant, and social behavior. We investigated the details of waste management in four Stigmaeopsis spp. and found differences in the location of the defecation site and in the way each species recognizes this site. Like S. miscanthi, Stigmaeopsis longus defecates at only one site and uses volatile chemical and tactile cues, whereas Stigmaeopsis takahashii and Stigmaeopsis saharai both defecate at two sites and use only tactile cues. We discuss the reasons for the waste management differences within the genus, and the relationship between the means of waste management, nest and group size.
Impact of Environmental Disturbance on the Stability and Benefits of Individual Status within Dominance Hierarchies
Authors: Sneddon Lynne U. , Hawkesworth Sophie , Braithwaite Victoria A. , Yerbury Julia 
Published: February 2006

AbstractChanges in environmental conditions affect social interactions and thus may modify an individual's competitive ability within a social group. We subjected three‐spined sticklebacks, Gasterosteus aculeatus, housed in groups of four individuals, to environmental perturbations to assess the impact on dominance hierarchy stability. Hierarchy stability decreased during increased turbulence or lowered water levels (‘simulated drought’) whereas control hierarchies became more stable in a constant environment. The dominant individual either became more aggressive and remained dominant during the environmental manipulation or was usurped by a lower rank member. Only simulated drought affected rates of aggression where levels of aggression were higher after the water level was dropped which may be the result of an increased encounter rate in these conditions. When there were large size differences between the group members, the dominant individual performed the greatest amount of aggression and ate the largest proportion of food and there was little aggressive behaviour from the lower ranks. In groups of similar‐sized individuals, aggression was much higher. The benefit of being dominant was to gain weight over the experimental period whereas ranks 2 and 3 lost weight. The lowest rank, 4, actually gained weight over the experimental period. This study suggests that it would benefit an individual to be dominant, highly aggressive and gain weight or be submissive, avoid aggressive interactions and, by sneakily obtaining access to food, also gain weight. Altering environmental conditions has a profound effect on social behaviour in this study.
Liver biopsy in the diagnosis of visceral leishmaniasis
Authors: Artan Reha , Yilmaz Aygen , Akçam Mustafa , Aksoy Nazif Hikmet 
Published: February 2006

AbstractAim:  To determine whether liver biopsy might be useful in the diagnosis of visceral leishmaniasis when bone marrow examination and serologic tests are inconclusive.Methods:  Over a 10‐year period, liver biopsy was performed in five children with suspected visceral leishmaniasis when indirect hemagglutination tests and bone marrow aspirations were not diagnostic.Results:  Leishmania amastigotes were seen in Kupffer cells in all patients. The accompanying liver histopathological findings were ischemic necrosis in two children, macrovesicular steatosis in two children, portal inflammatory inflammation in two children, and piecemeal necrosis in one child. During the study period, 32 additional pediatric visceral leishmaniasis cases were diagnosed by bone marrow examination.Conclusion:  Liver biopsy can be recommended for diagnosing suspected visceral leishmaniasis in children when serology and bone marrow aspiration are inconclusive.
A Firm‐Specific Analysis of the Exchange‐Rate Exposure of Dutch Firms
Authors: de Jong Abe , Ligterink Jeroen , Macrae Victor 
Published: February 2006

AbstractWe examine the relationship between exchange‐rate changes and stock returns for a sample of Dutch firms over 1994–1998. We find that over 50 per cent of the firms are significantly exposed to exchange‐rate risk. Furthermore, all firms with significant exchange‐rate exposure benefit from a depreciation of the Dutch guilder relative to a trade‐weighted currency index. This result confirms that firms in open economies, such as the Netherlands, exhibit significant exchange‐rate exposure. We collect unique information on the most relevant individual currencies for each firm with respect to their influence on firm value. Our results indicate that the use of a trade‐weighted currency index and the use of individual exchange rates are complements. We also measure the determinants of exchange‐rate exposure. As expected, we find that firm size and the foreign sales ratio are significantly and positively related to exchange‐rate exposure. In contrast with our hypothesis, off‐balance hedging using derivatives has no significant effects. Finally, in line with theory, we find that exposure is significantly reduced through on‐balance sheet hedging, i.e., through foreign loans and by producing in factories abroad.
Corporate Value, Managerial Stockholdings and Investments of Japanese Firms
Authors: Chen Carl R. , Guo Weiyu , Mande Vivek 
Published: February 2006

AbstractWe use a simultaneous equation model which treats firm value, investments and management ownership as endogenous to the firm. Our results show a feedback relation between corporate value and management ownership, i.e., corporate value is positively impacted by management ownership, which in turn is positively impacted by corporate value. Corporate value also affects investments made by the firm. We also find that the effect of the main bank on corporate value is positive but only up to a certain point; then, it turns negative. Supporting the argument that keiretsu firms have lower agency cost, we find that firms belonging to a keiretsu have higher valuations during the sample period. Finally, we find that management ownership increases as the ownership of the main bank, ownership of institutional holders and cross‐holdings decreases, suggesting a substitution effect among these monitoring forces. Our results indicate that ignoring the web of these relationships leads to incorrect inferences.
The Multijurisdictional Disclosure System and Value of Equity Offerings
Authors: Mittoo Usha R. 
Published: February 2006

AbstractThe Canada and US multijurisdictional disclosure system (MJDS) implemented in 1991 lowered the indirect barriers for investors and issuers by easing reporting and disclosure requirements for cross‐border issues. This paper examines the impact of the MJDS and related regulatory changes on Canada–US equity market segmentation using a sample of Canadian seasoned equity offerings in the 1991–1998 period. We find that the number of cross‐border issues by Canadian firms increased, and the typical negative stock price reaction that accompanies seasoned equity issues declined over time, supporting increased integration between the two markets after the MJDS. We also document that cross‐border issues experience about 1.4 per cent lower negative stock price reaction compared with domestic issues, consistent with Canada–US market segmentation. We find mixed support for Merton's (1987) investor recognition hypothesis. While Canadian firms cross‐listed in the US experience a less adverse price reaction to their cross‐border offerings compared with their non‐US‐listed peers, there is no significant difference between the two groups in the case of purely domestic issues.
Frontier Technology and Absorptive Capacity: Evidence from OECD Manufacturing Industries*
Authors: Kneller Richard , Stevens Philip Andrew 
Published: February 2006

AbstractIn this paper, we examine the three facets of technology: its creation, dispersion and absorption. We investigate whether differences in absorptive capacity help to explain cross‐country differences in the level of productivity. We utilize stochastic frontier analysis to investigate two potential sources of this inefficiency – differences in human capital and R&D – for nine industries in 12 Organization for Economic Co‐operation and Development (OECD) countries over the period 1973–91. We find that inefficiency in production does indeed exist and it depends upon the level of human capital of the country's workforce. Evidence that the amount of R&D an industry undertakes is also important is less robust.
Occupational Labour Demand and the Sources of Non‐neutral Technical Change*
Authors: Chan Wing H. , Rich Daniel P. 
Published: February 2006

AbstractThis article introduces a two‐step empirical approach for examining both the nature and sources of non‐neutral technical change across multiple occupations. First, conventional labour‐demand parameter estimates and unbiased tests for neutrality are obtained in the context of a flexible cost system. The resulting input‐specific indices of technical change, unconstrained with respect to time path, facilitate subsequent evaluation of proposed sources. In our application to employment decisions of airline firms, we find labour‐saving technical change that is non‐neutral across occupations. We also document occupation‐specific responses to aircraft technology adoption, route system developments and an unprecedented range of technical change elements.
Would it not be sensible to start by trying to identify the form which the growth of conventional input efficiency has taken and then proceed to tackle the intriguing, but quite distinct, question of the sources of such growth? As it is now, the typical modus operandi implicitly involves an effort to dispose of both issues by a single stroke. David and van de Klundert (1965)
Whatever Happened to Goldilocks? The Role of Expectations in Estimates of the NAIRU in the US and the UK*
Authors: Driver Rebecca L. , Greenslade Jennifer V. , Pierse Richard G. 
Published: February 2006

AbstractDuring the second half of the 1990s the US economy was characterized as the Goldilocks economy: not too hot, nor too cold, but just right. It was argued that this represented a new paradigm, enabling unemployment to remain low without igniting inflationary pressure. We examine the evidence for a change in the relationship between inflation and unemployment for the US and UK using Phillips curve models. The impact of including explicit inflation expectations is also considered. Inflation expectations are found to play an important role, particularly in the US. When expectations are included there is still evidence that the non‐accelerating inflation rate of unemployment (NAIRU) steadily declined during the late 1990s, although this decline in the US NAIRU is not found solely in the 1990s.
Consumption and Aggregate Constraints: International Evidence*
Authors: Dejuan Joseph P. , Luengo‐Prado Maria Jose 
Published: February 2006

AbstractThis paper documents that region‐level consumption exhibits excess sensitivity to lagged region‐level income in Italy, Japan, Spain, the UK and West Germany. However, region‐specific consumption exhibits substantially less sensitivity to lagged region‐specific income. Moreover, excess sensitivity is inversely related to standard measures of openness and credit market integration and for most countries, it has decreased over time. These findings are consistent with the results reported by Ostergaard et al. [Journal of Political Economy (2002) Vol. 110, pp. 634–645] for US states and Canadian provinces, and provide empirical support for the hypothesis that closed‐economy constraints may partly be responsible for the excess sensitivity phenomenon in aggregate data.
Testing for Panel Cointegration with Multiple Structural Breaks*
Authors: Westerlund Joakim 
Published: February 2006

AbstractThis paper proposes a Lagrange multiplier (LM) test for the null hypothesis of cointegration that allows for the possibility of multiple structural breaks in both the level and trend of a cointegrated panel regression. The test is general enough to allow for endogenous regressors, serial correlation and an unknown number of breaks that may be located at different dates for different individuals. We derive the limiting distribution of the test and conduct a small Monte Carlo study to investigate its finite sample properties. In our empirical application to the solvency of the current account, we find evidence of cointegration between saving and investment once a level break is accommodated.