bluuebunny/crossref_metadata_2025_split huggingface dataset:
A randomized controlled trial of the effectiveness of a one‐step conditioning agent in sealant placement: 6‐month results
Authors: BURBRIDGE L. , NUGENT Z. , DEERY C. 
Published: July 2006

Summary.  Aim.  The objectives of this study were: to compare the retention of fissure sealants (sealants) placed on occlusal surfaces following the use of a self‐etching priming agent and traditional acid etch; to compare the caries incidence of occlusal surfaces sealed using the two techniques; and to compare the ease of placement of sealant following the use of the two techniques, as assessed by subjects and operators.Design.  The study took the form of a randomized controlled trial conducted in UK National Health Service community dental service and dental hospital clinics. Sixty subjects were recruited to this study by seven dental professionals who placed sealants on lower permanent molar pairs. The technique used for enamel preparation prior to sealant placement on the right and left side of the lower arch was randomized. On one side of the lower arch, Xeno® III was used to prepare the occlusal enamel, and on the other, phosphoric acid etch together with Prime & Bond® was used. Opaque Delton® was used to seal all surfaces. Subjects were blinded to the techniques used. The subjects and operators recorded their impressions of the techniques used on individual questionnaires.Results.  Forty‐six (77%) of the 60 subjects were reviewed by the principal researcher after 6 months. The retention of the acid‐etch group was significantly superior (P < 0·01), as was the caries preventive effect (P < 0·01). Subjects tended to report that placement of sealants was easier following enamel preparation with Xeno® III (P = 0·085), and in the opinion of the operators, sealants were significantly easier to place when using Xeno® III (P = 0·016).Conclusions.  In view of the findings of this investigation, best practice for the placement of sealants remains enamel preparation with acid etch and the use of an intermediate bonding layer.
Dentinal carious lesion in three dimensions
Authors: WONG F. S. L. , WILLMOTT N. S. , DAVIS G. R. 
Published: July 2006

Summary.  Aim.  The aim of this study was to show the morphology of the carious lesion in dentine in three dimensions (3D).Design.  A novel high‐definition X‐ray microtomography (XMT) scanner was used to scan 10 carious primary molars at a resolution of 15 × 15 × 15 µm3. A stack of ∼640 XMT slices were recorded for each tooth. Using this data set and a volume rendering algorithm, each tooth was reconstructed in 3D. The VG Studio Max 1·0 visualization software package was used to make normal enamel and dentine transparent to show the carious lesions in 3D. A video film, comprised of the rendered images from 60 viewing angles rotating through 360°, was produced to show the carious lesion and its relation to the pulp in a three‐dimensional perspective (http://www.smd.qmul.ac.uk/dental/oralgrowdev/biophysics/xmt/images/carious.mpg).Results.  These images showed that carious lesions in dentine were bowl‐shaped. The pulp adjacent to the carious lesion was also observed to mimic the base of the bowl‐shaped lesion.Conclusions.  It was concluded from the teeth studied that the shape at the base of the carious lesion in dentine is curved in 3D, rather than conical, as traditionally believed from two‐dimensional image interpretation. Further 3D studies are needed to investigate whether the bowl‐shaped carious lesions in dentine also apply to caries in other types of teeth.
Efficacy of clinical supervision: influence on job satisfaction, burnout and quality of care
Authors: Hyrkäs Kristiina , Appelqvist‐Schmidlechner Kaija , Haataja Riina 
Published: July 2006

Aim.  This paper reports a study to determine how supervisees’ backgrounds and surrounding infrastructure predict the efficacy of clinical supervision among Finnish nursing staff, their job satisfaction, levels of burnout and perceptions of the quality of care.Background.  Several studies have described the effects of clinical supervision, but few have focused on evaluating it. Until recently, no studies have examined how clinical supervision evaluations are related to supervisees’ backgrounds, surrounding infrastructure or respondents’ levels of burnout, job satisfaction and perceptions of the quality of care.Methods.  The survey involved supervisees completing a range of standardized and validated evaluation measures. The respondents were identified from 12 regional, central and university hospitals across Finland (n = 799). The data collection took place from October 2000 to February 2001.Findings.  The evaluations varied statistically significantly and were associated with statistically significant variations in the respondents’ backgrounds. Clinical supervision infrastructure was also strongly related to evaluation scores. Supervisees’ age, education, gender, employment status, area of specialty, working hours, work experience and experience as a supervisor were statistically significant predictors for evaluations of the efficacy of clinical supervision. These evaluations of clinical supervision were also found to predict the respondents’ job satisfaction, levels of burnout and assessments of good nursing.Conclusions.  Nursing staff, especially those who have over 10 years’ work experience, work in general care, have a nursing diploma, are non‐tenured, work part‐time and work 24‐hour rotating shifts can benefit from clinical supervision. However, resources need to be invested in supervisor education and nursing staff need to be encouraged to start working in both supervisor and supervisee roles because of the positive effects on job satisfaction and quality of care.
Climate impacts at multiple scales: evidence for differential population responses in juvenile Chinook salmon
Authors: CROZIER LISA G. , ZABEL RICHARD W. 
Published: July 2006

Summary

We explored differential population responses to climate in 18 populations of threatened spring–summer Chinook salmon Onchorynchus tshawytscha in the Salmon River basin, Idaho.
Using data from a long‐term mark–release–recapture study of juvenile survival, we found that fall stream flow is the best predictor of average survival across all populations.
To determine whether all populations responded similarly to climate, we used a cluster analysis to group populations that had similar annual fluctuations in survival. The populations grouped into four clusters, and different environmental factors were important for different clusters.
Survival in two of the clusters was negatively correlated with summer temperature, and survival in the other two clusters was positively correlated with minimum fall stream flow, which in turn depends on snow pack from the previous winter.
Using classification and regression tree analysis, we identified stream width and stream temperature as key habitat factors that shape the responses of individual populations to climate.
Climate change will likely have different impacts on different populations within this metapopulation, and recognizing this diversity is important for accurately assessing risks.
Historical biogeography of lowland species of toads (Bufo) across the Trans‐Mexican Neovolcanic Belt and the Isthmus of Tehuantepec
Authors: Mulcahy Daniel G. , Morrill Benson H. , Mendelson Joseph R. 
Published: July 2006

AbstractAim In this study, we investigate phylogeographic structure in two different species groups of lowland toads. First, we further investigate strict parapatry of the Pliocene‐vicariantBufo valliceps/B. nebuliferspecies pair. Secondly, we test for similar phylogeographic structure in the distantly related toadB. marinus, a species we hypothesize will show a Pleistocene dispersal across the same area.Location The eastern extension of the Trans‐Mexican Neovolcanic Belt (TMNB) contacts the Atlantic Coast in central Veracruz, Mexico. Although it is not a massive structure at this eastern terminus, the TMNB has nonetheless effected vicariance and subsequent speciation in several groups of animals. The Isthmus of Tehuantepec unites the North American continent with Nuclear Central America and is also known to be a biogeographic barrier for many taxa.Methods We use sequence data from two mitochondrial DNA genes (c. 550 base‐pairs (bp) of 16S andc. 420 bp of cytb) from 58 individuals of theB. valliceps/nebulifercomplex, collected from 24 localities. We also present homologous sequence data from 23 individuals ofB. marinus, collected from 12 localities. We conduct maximum‐parsimony, maximum‐likelihood and Bayesian analyses to investigate phylogeographic structure. We then use parsimony‐ and likelihood‐based topology tests to assess alternative phylogenetic hypotheses and use a previously calibrated molecular rate of evolution to estimate dates of divergence.Results Our results further define the parapatric contact zone across the TMNB between the Pliocene‐vicariant sister speciesB. vallicepsandB. nebulifer. In contrast, phylogenetic structure among populations ofB. marinusacross the TMNB is much shallower, suggesting a more recent Pleistocene dispersal in this species. In addition, we found phylogeographic structure associated with the Isthmus of Tehuantepec in both species groups.Main conclusions The existence of a Pliocene–Pleistocene seaway across the Isthmus of Tehuantepec has been controversial. Our data depict clades on either side of the isthmus within two distinct species (B. vallicepsandB. marinus), although none of the clades associated with the isthmus, for either species, are reciprocally monophyletic. In theB. valliceps/B. nebulifercomplex, the TMNB separation appears to predate the isthmian break, whereas inB. marinusdispersal across the TMNB has occurred subsequent to the presence of a barrier at the Isthmus of Tehuantepec.
Unusual abundance–range size relationship in an Afromontane bird community: the effect of geographical isolation?
Authors: Reif Jiří , Hořák David , Sedláček Ondřej , Riegert Jan , Pešata Michal , Hrázský Záboj , Janeček Štěpán , Storch David 
Published: July 2006

AbstractAim To show that the frequently reported positive trend in the abundance–range‐size relationship does not hold true within a montane bird community of Afrotropical highlands; to test possible explanations of the extraordinary shape of this relationship; and to discuss the influence of island effects on patterns of bird abundance in the Cameroon Mountains.Location Bamenda Highlands, Cameroon, Western Africa.Methods We censused birds during the breeding season in November and December 2003 using a point‐count method and mapped habitat structure at these census points. Local habitat requirements of each species detected by point counts were quantified using canonical correspondence analysis, and the size of geographical ranges of species was measured from their distribution maps for sub‐Saharan Africa. We tested differences in abundance, niche breadth and niche position between three species groups: endemic bird species of the Cameroon Mountains, non‐endemic Afromontane species, and widespread species.Results We detected neither a positive nor negative abundance–range‐size relationship in the bird community studied. This pattern was caused by the similar abundance of widespread, endemic and non‐endemic montane bird species. Moreover, endemic and non‐endemic montane species had broader local niches than widespread species. The widespread species also used more atypical habitats, as indicated by the slightly larger values of their niche positions.Main conclusions The relationship detected between abundance and range size does not correspond with that inferred from contemporary macroecological theory. We suggest that island effects are responsible for the observed pattern. Relatively high abundances of montane species are probably caused by their adaptation to local environmental conditions, which was enabled by climatic stability and the isolation of montane forest in the Cameroon Mountains. Such a unique environment provides a less suitable habitat for widespread species. Montane species, which are abundant at present, may also have had large ranges in glacial periods, but their post‐glacial distribution may have become restricted after the retreat of the montane forest. On the basis of comparison of our results with studies describing the abundance structure of bird communities in other montane areas in the Afrotropics, we suggest that the detected patterns may be universal throughout Afromontane forests.
Historical biogeography ofRhododendronsectionVireyaand the Malesian Archipelago
Authors: Brown Gillian K. , Nelson Gareth , Ladiges Pauline Y. 
Published: July 2006

AbstractAim Vireya rhododendrons are distinctive and easily recognizable by their general form; however, they are virtually circumscribed geographically, predominantly distributed throughout the biogeographically intriguing Malesian Archipelago. Hypotheses of the evolutionary relationships of the group have been proposed but the biogeography of vireyas has not been analysed based on molecular phylogeny. Recently, the first detailed molecular phylogenetic investigation of sectionVireyawas completed based on cp‐ and nrDNA sequence data, therefore making this cladistic biogeographic study of vireya rhododendrons possible.Location Malesia, Australia, Solomon Islands, Taiwan, Himalayas, north Vietnam and south China.Methods Based on distribution maps, areas of endemism were determined for the biogeographic region of Malesia. Area relationships were analysed based on a recent molecular phylogeny of species in sectionVireya. The method of paralogy‐free subtree analysis was applied.Results Individual distribution maps were produced for 74 species ofRhododendronsectionVireya. Species clades with bootstrap support proved to be biogeographically informative. Major clades correspond to three regions: eastern Malesia, western/middle Malesia and Taiwan/north Vietnam/south China. Within eastern Malesia, Australia, New Guinea, the Bismarck Archipelago and Solomon Islands are related. In western Malesia, northern Philippines, Borneo, southern Moluccas and north and west Sulawesi are related. These areas are more distantly related to Sumatra, the Malay peninsula, Java, Bali, Palawan, Lesser Sunda islands and the southern Philippines. The position of the Himalayas is equivocal and part of a basal polytomy in the summary area cladogram.Main conclusions Two alternative hypotheses are proposed for the evolution of vireya rhododendrons based on the pattern of area relationships. The first hypothesis is that the vireyas are an old group, with ancestors present on Gondwana, rifting north in the Cretaceous. The second alternative hypothesis is that vireyas are a young group that has dispersed eastwards from India to Australia and the Solomon Islands since the current Malesian islands formed.
Fine‐scale genetic structure and dispersal in cooperatively breeding apostlebirds
Authors: WOXVOLD IAIN A. , ADCOCK GREG J. , MULDER RAOUL A. 
Published: July 2006

AbstractIn cooperatively breeding species, restricted dispersal of offspring leads to clustering of closely related individuals, increasing the potential both for indirect genetic benefits and inbreeding costs. In apostlebirds (Struthidea cinerea), philopatry by both sexes results in the formation of large (up to 17 birds), predominantly sedentary breeding groups that remain stable throughout the year. We examined patterns of relatedness and fine‐scale genetic structure within a population of apostlebirds using six polymorphic microsatellite loci. We found evidence of fine‐scale genetic structure within the study population that is consistent with behavioural observations of short‐distance dispersal, natal philopatry by both sexes and restricted movement of breeding groups between seasons. Global FST values among breeding groups were significantly positive, and the average level of pairwise relatedness was significantly higher for individuals within groups than between groups. For individuals from different breeding groups, geographical distance was negatively correlated with pairwise relatedness and positively correlated with pairwise FST. However, when each sex was examined separately, this pattern was significant only among males, suggesting that females may disperse over longer distances. We discuss the potential for kin selection to influence the evolution and maintenance of cooperative breeding in apostlebirds. Our results demonstrate that spatial genetic structural analysis offers a useful alternative to field observations in examining dispersal patterns of cooperative breeders.
Phylogeography of the Percichthyidae (Pisces) in Patagonia: roles of orogeny, glaciation, and volcanism
Authors: RUZZANTE DANIEL E. , WALDE SANDRA J. , CUSSAC VÍCTOR E. , DALEBOUT MEREL L. , SEIBERT JACOB , ORTUBAY SILVIA , HABIT EVELYN 
Published: July 2006

AbstractWe used molecular evidence to examine the roles that vicariance mechanisms (mountain‐building and drainage changes during the Pleistocene) have played in producing phylogeographical structure within and among South American fish species of the temperate perch family Percichthyidae. The percichthyids include two South American genera, Percichthys and Percilia, each containing several species, all of which are endemic to southern Argentina and Chile (Patagonia). Maximum‐likelihood phylogenies constructed using mitochondrial DNA (mtDNA) control region haplotypes and nuclear GnRH3‐2 intron allele sequences support the current taxonomy at the genus level (both Percichthys and Percilia form strongly supported, monophyletic clades) but indicate that species‐level designations need revision. Phylogeographical patterns at the mtDNA support the hypothesis that the Andes have been a major barrier to gene flow. Most species diversity occurs in watersheds to the west of the Andes, together with some ancient divergences among conspecific populations. In contrast, only one species (Percichthys trucha) is found east of the Andes, and little to no phylogeographical structure occurs among populations in this region. Mismatch analyses of mtDNA sequences suggest that eastern populations last went through a major bottleneck c. 188 000 bp, a date consistent with the onset of the penultimate and largest Pleistocene glaciation in Patagonia. We suggest that eastern populations have undergone repeated founder‐flush events as a consequence of glacial cycles, and that the shallow phylogeny is due to mixing during recolonization periods. The area of greater diversity west of the Andes lies outside the northern limit of the glaciers. mtDNA mismatch analysis of the genus Percilia which is restricted to this area suggests a long‐established population at equilibrium. We conclude that patterns of genetic diversity in these South American genera have been primarily influenced by barriers to gene flow (Andean orogeny, and to a lesser extent, isolation in river drainages), and by glacial cycles, which have resulted in population contraction, re‐arrangement of some watersheds, and the temporary breakdown of dispersal barriers among eastern river systems.
Patterns of recurrent evolution and geographic parthenogenesis within apomictic polyploid Easter daises (Townsendia hookeri)
Authors: THOMPSON STACEY LEE , WHITTON JEANNETTE 
Published: July 2006

AbstractGeographic patterns of parthenogenesis and the number of transitions from sexual diploidy to asexual (apomictic) autopolyploidy were examined for 40 populations of the Easter daisy, Townsendia hookeri. Analyses of pollen diameter and stainability characterized 15 sexual diploid and 25 apomictic polyploid populations from throughout the plant's western North American range. Sexual diploids were restricted to two Wisconsin refugia: Colorado/Wyoming, south of the ice sheets, and northern Yukon/Beringia. Chloroplast DNA sequencing uncovered 17 polymorphisms within the ndhF gene and trnK intron, yielding 10 haplotypes. Phylogenetic analyses indicated that five exclusively polyploid haplotypes were derived from four haplotypes that are shared among ploidies, conservatively inferring a minimum of four origins of apomictic polyploidy. Three of these apomictic polyploid origins were derived from southern sexual diploids, while the fourth origin was derived from northern sexual diploids. Analyses of regional diversity were suggestive of a formerly broad distribution for sexual diploids that has become subsequently fragmented, possibly due to the last round of glaciation. As sexual diploids were exclusively found north and south of the glacial maximum, while formerly glaciated areas were exclusively inhabited by asexual polyploids derived from both northern and southern sexual lineages, it is more likely that patterns of glaciation, as opposed to a particular latitudinal trend, played a causal role in the establishment of the observed pattern of geographic parthenogenesis in Easter daisies.
Genetic breeding system and investment patterns within nests of Dawson's burrowing bee (Amegilla dawsoni) (Hymenoptera: Anthophorini)
Authors: BEVERIDGE MAXINE , SIMMONS LEIGH W. , ALCOCK JOHN 
Published: July 2006

AbstractDawson's burrowing bee is a large solitary ground‐nesting bee endemic to the arid zone of Western Australia. In this study, we use microsatellite markers to analyse the genotypes of offspring from individual nests to determine the number of effective mates for each female. From these data we have determined that females almost certainly mate only once which is consistent with male reproductive tactics that include protandry and intense male–male competition for access to virgin females. We also use the molecular data to show that the nesting female is the mother of all the offspring of her nest and that brood parasitism is unlikely in this species. The data indicate that females make daughters at the beginning of the season followed by large sons in the middle, and then small sons at the end. Females often place one brood cell directly above another. The distribution of sex and morph in these doublets follows a pattern with most containing a female on the bottom and a minor male on the top, followed by almost equal numbers of female on top of female and minor male on top of major male. This pattern is likely favoured by emergence patterns, with males emerging before females and minor males emerging before major males. We suggest that although minor males have low reproductive success, their production may nonetheless be beneficial in that minor males open up emergence tunnels for their larger and reproductively more valuable siblings. In addition, minor males may be a best of a bad job product arising from changes in the costs to nesting females of gathering brood provisions over the course of the flight season.