bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal variation in the female components of reproductive success over the extended flowering season of a Mediterranean perennial herb
Authors: Picó F. Xavier , Retana J.
Published: December 2004

We examined the reproductive success of the perennial herb Lobularia maritima during its extended flowering and fruiting season. The within‐ and between‐year variability of the female components of reproductive success (from flower, fruit and seed production to seed survival, seed germination and seedling establishment) were analysed during four flowering seasons. All the components of reproductive success studied showed a significant within‐ and between‐year variation. September was the period of the year with the maximum values of flower and fruit production, and the highest germination and establishment rates. Nevertheless, seed losses due to both predispersal and postdispersal seed predation during this period were also the highest, seriously reducing seed output in this period. On the other hand, in those periods in which seed production was low, i.e. January and May, the percentage of seeds lost to seed predators was the lowest. Reproductive success in each period of the flowering season was estimated using a simple demographic model, in which the information concerning all the components already calculated was integrated. The two variables used to estimate reproductive success in each period, i.e. the number of new individuals produced per plant and the probability of a seed becoming an adult plant, showed relatively small differences over the year. These results suggest a counter‐balance of the different components of reproductive success in this species, with favourable and unfavourable periods for the different components being compensated during its extended flowering season.
Resource depression by a trophic generalist in an acid stream
Authors: Ledger Mark E. , Hildrew Alan G.
Published: December 2004

The occurrence and impact of algal grazing by invertebrates is widespread and well known in circumneutral streams but poorly understood in acidified streams, where specialist grazing taxa are absent. We examined the ability of the generalist stonefly, Nemurella pictetii
(Plecoptera: Nemouridae), maintained at different densities using
in‐stream experimental enclosures, to depress the biofilm resources
coating substrata in an acid stream. Nymphs were reared on the epilithic
biofilm coating cobbles in clear aquaria in Lone Oak at 0, 0.5, 1 and 4
times ambient density and their growth rate compared. The biomass and
algal taxonomic composition of the biofilm was also compared among
treatments and contrasted with stones from the stream. 
After 23 d, biofilm resources, evidenced by descriptors such as diatom
abundance, chlorophyll, carbohydrate and protein content, had been
depressed by the nymphs. The acidobiontic diatom Eunotia exigua
was harvested more efficiently than other algal taxa when nymphal
densities were high. Growth of N. pictetii nymphs in the
experimental channels was density dependent and the decline in growth of
the nymphs with increasing density was probably due to food limitation.
The ability of N. pictetii, often classed as a shredder of leafy detritus, to affect the biomass and composition of epilithic biofilm suggests that this abundant species is an important consumer of algae in acidified systems, where specialist herbivores are often absent. Grazing can clearly be important in acidified streams.
Do symbiotic fungi refresh themselves by incorporating their own or closely related spores into existing mycelium?
Authors: Kytöviita Minna‐Maarit
Published: December 2004

In most symbioses between plants and fungi sex is repressed in the fungal partner. In the notable exception of ectomycorrhizal symbioses, however, both partners frequently reproduce sexually. A possible role of spores is to function as vectors of genomic purging and recombination back to existing parental or to closely related mycelium.
Changes in intraspecific aggregation and the coexistence of predaceous apple mites
Authors: Slone D. H. , Croft B. A.
Published: December 2004

The leaves of an apple tree are a patchy environment for leaf‐inhabiting predaceous and phytophagous mites, consisting of discrete patches of leaf resources connected by relatively inhospitable petioles and branches. We investigated four species of predaceous mites (Amblyseius andersoni, Galendromus occidentalis, Typhlodromus pyri (Acari: Phytoseiidae), and Zetzellia mali (Acari: Stigmaeidae)) inhabiting ‘Red Delicious’ apple trees (Malus pumila). These mites experience intra‐guild predation (IGP), and we hypothesized that the vulnerable species would show increased aggregation when they are in plots with other predators. We also hypothesized that the increase in aggregation will be proportional to the vulnerability of the predator to IGP. We measured intraspecific aggregation with a binomial model that measures P(I), the amount of space a species occupies at a given average density, and compares this statistic among species at a common average density: samples that exhibit lower values of P(I) at a particular average density are considered to be more aggregated. We measured P(I) for the predaceous mites over four years, combining counts of all life stages. Data were segregated into groups with plots containing each predator alone, and each predator together with combinations of other predators. G. occidentalis and Z. mali showed significant increases in aggregation when other predators were present, with G. occidentalis showing the greatest change. T. pyri showed significant change only in the presence of Z. mali. A. andersoni, the largest mite studied here, showed no change in aggregation in the presence of other predators. We discuss possible causes of these changes in intraspecific aggregation and how they may promote long‐term coexistence of predaceous mites.
The ecological significance of toxic nectar
Authors: Adler Lynn S.
Published: December 2004

Although plant‐herbivore and plant‐pollinator interactions have traditionally been studied separately, many traits are simultaneously under selection by both herbivores and pollinators. For example, secondary compounds commonly associated with herbivore defense have been found in the nectar of many plant species, and many plants produce nectar that is toxic or repellent to some floral visitors. Although secondary compounds in nectar and toxic nectar are geographically and phylogenetically widespread, their ecological significance is poorly understood. Several hypotheses have been proposed for the possible functions of toxic nectar, including encouraging specialist pollinators, deterring nectar robbers, preventing microbial degradation of nectar, and altering pollinator behavior. All of these hypotheses rest on the assumption that the benefits of toxic nectar must outweigh possible costs; however, to date no study has demonstrated that toxic nectar provides fitness benefits for any plant. Therefore, in addition to these adaptive hypotheses, we should also consider the hypothesis that toxic nectar provides no benefits or is tolerably detrimental to plants, and occurs due to previous selection pressures or pleiotropic constraints. For example, secondary compounds may be transported into nectar as a consequence of their presence in phloem, rather than due to direct selection for toxic nectar. Experimental approaches are necessary to understand the role of toxic nectar in plant‐animal interactions.
Resource matching and population dynamics in a two‐patch system
Authors: Ranta Esa , Kaitala Veijo
Published: December 2004

We study resource matching – the relationship between resource supply and forager numbers – under conditions of fluctuating population dynamics in a two‐patch system. For the inter‐patch dispersal we apply the patch‐departure rule following the principle of the ideal free distribution: leave the current patch of residence if local conditions are worse than conditions elsewhere on average. We show that such a dispersal rule synchronises cyclic and chaotic local population dynamics, but unlike many other dispersal rules, leaves the underlying population dynamics untouched. We also show that the IFD dispersal rule is not very sensitive to biased information and navigation failures during the dispersal phase. Even under such circumstances we observe a quick process of populations becoming synchronised, even when the population dynamics are chaotic. We conclude that an IFD patch‐departure rule represents an ESS dispersal behaviour towards which the dispersal patterns should evolve.
The effect of spatio‐temporal variation in understanding the fruit crop size hypothesis
Authors: Ortiz‐Pulido Raúl , Rico‐Gray Victor
Published: December 2004

In order to evaluate the ‘fruit crop size’ hypothesis, we analyzed the effect of fruit availability on the number of visits by birds and on the proportion of removed fruits, and on how much of the variation in the proportion of removed fruits could be explained by spatio‐temporal variability. Fieldwork was done on the coast of the state of Veracruz, Mexico, using the small tree Bursera fagaroides (Burseraceae) and its frugivorous feeding assemblage, on four hills during four years. The number of fruits produced, the number of visits by birds, and the proportion of removed fruits varied between years with more than half an order of magnitude. The number of available fruits was associated to both the number of visits by birds and the proportion of fruits removed from each plant individual, and supports the fruit crop size hypothesis. However, the hypothesis varies in strength depending on total fruit production by the population per year and per hill. The spatio‐temporal variation of the system was the effect of variation in the intensity of fructification between years and hills; the inclusion of spatio‐temporal variability helped to explain most of the variation found in our results. The latter approach may explain the explain the conflicting results found by other authors in studies done in only one year or at one site, where variation is greatly reduced. Considering the number of published reports, a meta‐analysis seems to be in order to determine the existence of a general effect between fruit production, the number of visits by birds and the proportion of fruits removed. If this is possible, we hypothezise that the association between fruit production and the number of visits by birds should be of low intensity.
Trading off mortality risk against foraging effort in damselflies that differ in life cycle length
Authors: Stoks Robby , Johansson Frank
Published: December 2004

Life history theory predicts that size and age at emergence depend on the slope and shape of the relationship between mortality rate and foraging effort. Given the high expected foraging effort in obligate univoltine species compared with semivoltine species we expected a low slope and an increase in foraging effort in the presence of a predator for the former and the opposite pattern for the latter. We tested these predictions in two damselfly species of the univoltine genus Lestes, and the semivoltine genus Coenagrion when confronted with perch. We determined for each of the four study species the relationships between mortality rate and foraging effort at an individual level. As expected by the different growth demands associated with differences in life cycle length, both Lestes species had a higher foraging effort than the two Coenagrion species in the absence as well as in the presence of perch. As a result, lestids also suffered a higher mortality rate. The slope of the regression between mortality rate and foraging effort was, as predicted, lower for lestids than for coenagrionids, for one species pair. Despite this, and opposite to our prediction, the lestids decreased foraging effort even more than coenagrionids in the presence of perch. We discuss these findings in the light of life history responses in species that differ in life cycle length.
Eelgrass, Zostera marina, growth along depth gradients: upper boundaries of the variation as a powerful predictive tool
Authors: Krause‐Jensen Dorte , Middelboe Anne Lise , Sand‐Jensen Kaj , Christensen Peter Bondo
Published: December 2004

1200 measurements of eelgrass (Zostera marina) biomass, shoot density and cover along 19 depth gradients in Øresund, located between Denmark and Sweden, were analysed to characterise growth of eelgrass in relation to depth. The large data set allowed analyses of boundaries of distribution as well as of average trends. Natural variability is large in shallow water where populations are disturbed by wave action and other physical parameters. Models based on average values, therefore, did not adequately describe growth regulation by resources, and only explained a minor part (up to 30%) of the overall variation in data. In contrast, boundary functions, which describe the upper bounds of distributions, focus on the variation produced by the ultimately growth‐regulating resource, and therefore provide models with high predictive power. An exponential model explained up to 90% of the variation in upper bounds of eelgrass shoot density as a function of depth and indicated that shoot density was ultimately regulated by light availability. The boundary functions demonstrated that eelgrass shoot density, biomass and cover followed markedly different patterns as functions of depth and were affected differently by the factors governing their distribution. In addition, boundary functions revealed informative spatial structures in data and illustrated whether a given general trend was caused by changes in maximum values, minimum values or both. For example, upper and lower boundaries of biomass‐shoot density relations changed markedly with depth, demonstrating depth‐related changes in intraspecific succession and competition patterns. Boundary functions are therefore suggested as a promising tool for analysing ultimate regulating factors of distribution and growth of organisms when large data sets are available.
Intraspecific competition and subterranean herbivory: individual and interactive effects on bush lupine
Authors: Maron John L.
Published: December 2004

High mortality of plants growing in dense monospecific stands (i.e. self‐thinning) usually results from intense intraspecific competition. However, inconspicuous below‐ground insect herbivory might be a potent but overlooked source of mortality within dense stands of plants, particularly if crowding limits a plant's ability to compensate for herbivore damage. Here I ask how high conspecific density influences a plant's ability to cope with heavy below‐ground insect herbivory.  I manipulated conspecific density and exposure to an abundant root‐borer, the ghost moth (Hepialus californicus), and examined the impacts on the fecundity, growth, and survival of bush lupine (Lupinus arboreus), a fast‐growing shrub that grows in dense monospecific stands in coastal grasslands. Both herbivory and intraspecific competition affected seed production, size, and mortality of bush lupine over the two years of the experiment. Plants consistently produced fewer seeds when growing at high versus low density and ghost moth herbivory also significantly reduced seed production. The negative effects of herbivory on plant fecundity were similar, regardless of plant density. In contrast, plant survival was affected by both competition, herbivory, and the interaction of these factors. In high density plots, plant survival was uniformly low (averaging 0.45–0.50); plants exposed to herbivores died from heavy herbivory, and plants protected from herbivores died due to intense intraspecific competition that compensated for losses due to herbivory. In low density plots, ghost moth herbivory similarly reduced lupine survival, from an average survival probability of 0.94 in plots protected from these herbivores to 0.55 in plots exposed to herbivory. Thus, results show that regardless of plant density, below‐ground herbivory can be a potent source of mortality.
Intrinsic guild structure: determination from competition experiments
Authors: Wilson J. Bastow , Roxburgh Stephen H.
Published: December 2004

A new approach is introduced for determining the intrinsic guild classification of a group of species. Previous delimitations of intrinsic guilds have used evidence of spatial distributions (i.e. species co‐occurrences), but this is rather indirect evidence. The new method is based on the results of species pairwise competition experiments, and thus uses direct data on species interactions. As with the spatial‐distribution intrinsic guild approach, no prior assumptions are made about the classification, nor about which characters are related to guild membership.  The method is applied to the results of two published experiments. For one, little independent evidence is available to judge the classification. There is no correlation between the guild classification obtained and gross morphology, but there is no reason to expect any such correlation. For the second experiment, intrinsic guild classifications had previously been obtained from distributional data, and the experimentally‐based intrinsic classifications was identical to a distributionally‐based one.  We suggest that combining evidence from field distributions with experimental evidence offers a rigorous way to determine the true guild structure of communities, offering convincing conclusions when the two lines of evidence converge.
Interactions between neighboring algae and snail grazing in structuring microdistribution patterns of periphyton
Authors: Kawata Masakado , Hayashi Mayuko , Hara Toshihiko
Published: December 2004

The micro‐distribution of periphyton (filamentous algae) on homogeneous substrates was examined in experimental tanks with and without the pressure of grazing snails. The growth of periphyton attached to artificial substrate was estimated at a small spatial scale (9.3 mm×9.3 mm cells) by varying the number of grazers (0, 5, or 10 snails per tank), using image processing analysis without removing the periphyton. The results suggest that periphyton growth within a cell was negatively affected by the biomass of periphyton in the cell but was positively affected by the biomass of periphyton in neighboring cells. A semivariogram analysis indicated that spatial heterogeneity increased with increasing grazing pressure. The size of patches was not clearly related to the number of snails, but there was a tendency for relative patch size to increase with snail density. Computer simulations were also conducted to examine factors affecting the degree of spatial heterogeneity. The simulation studies indicated that snails should graze a site that was previously grazed in order to produce the observed spatial heterogeneity of periphyton. The results also indicated that the positive effects of neighboring periphyton on the growth of algae might create patches. The interactions among neighboring algae and snail grazing might be an important factor creating the spatial heterogeneity of periphyton even on homogeneous substrates.
The role of lemming herbivory in the sex ratio and shoot demography of willow populations
Authors: Predavec Martin , Danell Kjell
Published: December 2004

We investigated the role of lemming herbivory on the age structure and physical form of a stand of willows (Salix lanata) using lemming scars on stems as an indication of past herbivory. Salix lanata had a female‐biased sex ratio comparable to that found in other willow species and it has been proposed that such a sex ratio may be due to selective herbivory on male genets. There was, however, no difference in the degree of scarring in male and female plants. Scarring did not appear to change the overall physical structure of the willows including the number of stems, the proportion of dead stems and the degree of branching. However, 72% of scarred 7 mm stems were dead, compared to only 22% of non‐scarred stems, suggesting that lemming herbivory may play a role in ramet death. There was a significant positive correlation between stem ages and the lemming cycle as determined by the frequency of scars. With experimental scarring, S. lanata increased its production of new shoots in relation to the degree of scarring. We suggest that this demonstrates a pattern of compensatory growth in willows, whereby they take advantage of a period of relatively low herbivory following the crash of the lemming populations in order to compensate for damage that occurred during the lemming peak.
Habitat selection by predators and prey in communities with asymmetrical intraguild predation
Authors: Heithaus Michael R.
Published: December 2004

Competition and predation have broad ecological consequences as they may influence individual behavior and community structure. In some cases, they are linked and predator and prey are also competitors (intraguild predation). I present a game theoretic model of habitat use by predators and prey under conditions of asymmetrical intraguild predation. This model predicts that when the diet of intraguild predators is restricted to intraguild prey and the resource for which predators and prey compete (the basal resource), co‐occurrence is only stable when dietary overlap is low and productivity of the basal resource is not high. The addition of alternative resources for predators results in co‐occurrence under all conditions. Variation in alternative resource productivity produces a continuum of intraguild prey distributions from matching relative habitat safety, to one that reflects both food and predation risk. When there is a substantial alternative resource for predators, the distribution of predators matches that of alternative resource availability while the distribution of prey is influenced by both habitat riskiness and food availability. The density and distribution of the predator's alternative resource thus influence habitat selection by the intraguild prey. This stresses the importance of indirect interactions in structuring habitat use in communities and the need to view habitat selection in a community context.
Economic globalization and oral health
Authors: Hobdell MH
Published: December 2004

OBJECTIVES: To briefly review the origins of economic globalization and examine the evidence available concerning its possible impact on oral health.

DESIGN: Based on Medline searches 1966–1999 and review of Health Wrights:Politics of Healthdatabase.

SPECIFIC ORAL DISEASES: Dental caries, destructive periodontal diseases, cancrum oris and oral cancer.

CONCLUSIONS: The reported growing disparity between rich and poor populations, both internationally and nationally, is arguably being exacerbated by economic globalization. Increasing levels of the above specific oral diseases might be attributed, in part, to this economic phenomenon.
Community organization and species richness of ants (Hymenoptera/Formicidae) in Mongolia along an ecological gradient from steppe to Gobi desert
Authors: Pfeiffer Martin , Chimedregzen Losol , Ulykpan Kaman
Published: December 2004

Aim Ants (Hymenoptera/Formicidae) have strong influences on ecosystems especially in arid regions. However, little is known about ants of the vast steppe and desert regions of Central Asia. Here we provide the first comprehensive study of ant communities in Mongolia, conducted along a north‐to‐south gradient in climate. We examined ants’ distribution patterns, assessed the impact of climatic parameters on community structure and species diversity and investigated the influence of the corresponding communities of plants.

Location Mongolia (Central Asia).

Methods We observed 31,956 ants at seed baits at 11 study sites along a transect from steppe to Gobi desert for which we attained meteorological data (mean yearly precipitation: 197 to 84 mm). Extra sampling was conducted at sugar and protein baits and by the inspection of different microhabitats. Vegetation patterns of each plot were recorded. Statistical evaluation comprised ordination and correlation.

Results We observed 15 species of ants at seed baits. Three faunal complexes of ants could be distinguished by detrended correspondence analysis (DCA): (1) in steppe baits were dominated byFormica‐ andMyrmica‐species, (2) in semi desert we found mostly species ofTetramorium,Myrmica,Proformica,Plagiolepis, andLeptothorax, and (3) in desertCataglyphis aenescensandMessor aciculatusdominated, andLasiuswas exclusively found there. Another 11 rare ant species were sampled by hand and at sugar baits. Altogether five ant species were new to the Mongolian fauna:Cardiocondyla koshewnikovi,Myrmica koreana,Myrmica pisarskii,Polyergus nigerrimus, andProformica kaszabi. Assignment of taxa to functional groups showed that in steppe cold climate specialists dominated, in semi desert we found mainly opportunists, and in desert hot climate specialists. Several functional groups know from arid zones in other parts of the world were missing. In desert certain species were highly dominant. First DCA scores of ant‐ and plant‐communities were highly correlated with each other and with climatic parameters. While plant species diversity was positively correlated with increasing northern latitude, ant diversity and ant species richness were not correlated with latitude and responded neither to precipitation, nor to any other climatic parameter. Semi desert was a transition zone between steppe and desert, with high species richness. Ant genus composition of the ecotone overlapped with both other regions. However, beta diversity between pairs of plots within this zone was low, indicating a small‐scale mosaic pattern.

Main conclusions The ant communities in the Mongolian steppe and desert zones were strongly influenced by low temperatures and differed in many aspects from the ant fauna in other arid ecosystems, especially in terms of species richness, diversity of feeding guilds, and richness of functional groups.
Extracellular matrix glycoproteins and diffusion barriers in human astrocytic tumours
Authors: Zámecník J. , Vargová L. , Homola A. , Kodet R. , Syková E.
Published: December 2004

The extracellular matrix (ECM) and changes in the size and geometry of the extracellular space (ECS) in tumour tissue are thought to be of critical importance in influencing the migratory abilities of tumour cells as well as the delivery of therapeutic agents into the tumour. In 21 astrocytic neoplasms, the ECM composition was investigatedin situby the immunohistochemical detection of ECM glycoproteins (tenascin, laminin, vitronectin, fibronectin, collagen types I–VI). To explain the changes in ECS size and to detect barriers to diffusion in the tumour tissue, the ECM composition, the cellularity, the density of glial fibrillary acidic protein (GFAP)‐positive tumour cell processes and the proliferative activity of the tumours were compared with the size and geometry of the ECS. The ECS volume fraction and the complex of hindrances to diffusion in the ECS (i.e. the tortuosity) were revealed by the real‐time iontophoretic tetramethylammonium method. Increased proliferative activity of the tumours correlated with increased ECS volume fraction and tortuosity. The tortuosity of the tumour tissue was not significantly influenced by tumour cell density. Higher tortuosity was found in low‐grade astrocytomas associated with the presence of a dense net of GFAP‐positive fibrillary processes of the tumour cells. The increase in tortuosity in high‐grade tumours correlated with an increased accumulation of ECM molecules, particularly of tenascin. We conclude that the increased malignancy of astrocytic tumours correlates with increases in both ECS volume and ECM deposition.
Management of chronic illness: voices of rural women
Authors: Sullivan Therese , Weinert Clarann , Cudney Shirley
Published: December 2004

Background.  The prevalence and cost of chronic illness globally and in the United States of America continue to escalate and the day‐to‐day management of these conditions presents a major challenge. The burden of chronic illness disproportionately affects vulnerable populations such as women and those living in rural areas.

Aim.  To add to the knowledge base of illness management by chronically ill rural women through examining their individual perceptions of the illness experience.

Method.  The Women to Women project provided a nursing research‐based computer intervention model for conducting support groups, providing health education, and fostering self‐care, via personal computers and evaluated its effect on the women's psychosocial health.

Findings.  Fatigue and pain were the major physical symptoms that impacted the women's quality of life, with depression and stress being the primary emotions they experienced. The characteristics of humour, hope, and courage were key in their successful adaptation to living with chronic illness.

Conclusions.  The women's voices relate how they manage their illness responses and adaptation mechanisms. The data provide nurses with information to heighten their sensitivity to clients’ day‐to‐day needs and experiences. It will assist them in their designing and planning of interventions that will enable clients to adapt and to have the best quality of life possible within the limitations of their chronic illnesses. The data are also important to nurses involved in rural research and theory development concerning self‐management and adaptation to chronic illnesses.
Hysterectomy: a case study of one woman's experience
Authors: Fleming Valerie
Published: December 2004

Background. There are many published qualitative studies in the large volume of literature about hysterectomy documenting themes common to the majority of participants, such as social support, feelings of illness and wellness, pain and resumption of normal life rather than events which were unique or exceptional.

Aim. This study explores the meaning of the experience of abdominal hysterectomy for one woman.

Methods. Single client case study method was used. An overview of case study is presented and the rationale for its selection as an appropriate methodology for this study given. The participant and her ‘significant others’ are introduced.

Findings. Four major themes relating to the participant's experience were identified: doubts and justifications, pain, embodiment and sense of betterness. These are discussed in relation to the participant, the research literature and nursing and medical practice.

Conclusion. Highlighting the case of one woman and analysing her experience as a single case study has produced a depth of material not previously available in other studies. The findings should be of use to staff working in gynaecological nursing, but could also be used in the education of nursing and midwifery students.
Educating for rural nursing practice
Authors: Kenny Amanda , Duckett Stephen
Published: December 2004

Background.  Rural hospitals in Australia, as in many countries, face challenges in ensuring that appropriate, quality services are provided.

Aims.  The overall aim of this study was to explore the issues that impact on the ability of rural hospitals to provide effective health care.

Methods.  We used a qualitative descriptive method and purposive sampling, and conducted interviews in hospitals in rural Victoria, Australia. The data collected enabled major issues that impact on hospital service delivery to be identified. Using thematic analysis, global themes were extracted and organized around a thematic network.

Findings.  The workforce was an important theme. Whilst the impact of medical shortages on hospital function has been considered in other studies, little consideration has been given to the rural nursing workforce. The need to maintain an appropriately educated rural nursing workforce emerged as one of the major issues that impact on rural hospital service delivery. In Australia, there has been a great deal of discussion about the educational preparation required for rural nursing practice, with the emphasis on postgraduate study. However, the majority of rural nurses do not have postgraduate qualifications and face significant barriers in obtaining them. Although the vast majority of literature claims that postgraduate preparation is vital for rural nursing practice, this research suggests that the future rural nursing workforce will be recruited from undergraduate courses in regional universities. However, there is a need to include specific theoretical and operational preparation in undergraduate education, to enable nurses to make the transition to rural practice more readily.

Conclusions.  Rural nurses are central to the delivery of health services in rural hospitals. Future rural nursing recruitment and retention hinges on ensuring that they have the confidence, knowledge and skills to deliver safe, appropriate and effective care.
Predictors of prostate cancer on repeat prostatic biopsy in men with serum total prostate‐specific antigen between 4.1 and 10 ng/mL
Authors: OKEGAWA TAKATSUGU , KINJO MANAMI , OHTA MASAYA , MIURA ICHIRO , HORIE SHIGEO , NUTAHARA KIKUO , HIGASHIHARA EIJI
Published: December 2004

Objectives: We determine whether the different molecular forms of prostate‐specific antigen (PSA) and other PSA variables can predict prostate cancer in men undergoing repeat prostate needle biopsy.

Methods: Between 1997 and 2001, repeat biopsy was performed in 97 patients who had undergone prior negative prostate biopsy. The ability of total PSA (tPSA), complexed PSA (cPSA), free PSA (fPSA), free‐to‐total PSA (fPSA/tPSA), free‐to‐complexed PSA (fPSA/cPSA), complexed‐to‐total PSA (cPSA/tPSA), tPSA density (tPSAD), cPSA density (cPSAD), transition zone tPSA density (tPSATZ) and transition zone cPSA density (cPSATZ) was assessed by univariate and multivariate analyzes as well as receiver operating characteristics (ROC) curves.

Results: Prostate cancer on repeat biopsy was detected in 24% of subjects (23 of 97) who had a negative initial biopsy. The PSA parameters cut‐off to ensure a 96% sensitivity of cancer detection, were 29% using fPSA/tPSA, 32% using fPSA/cPSA, 0.18 ng/mL/cc using tPSATZ and 0.16 ng/mL/cc using cPSATZ. The fPSA/tPSA would have prevented 32% of negative biopsies, the fPSA/cPSA 28%, the tPSATZ 23% and the cPSATZ 30%. ROC curve analysis fPSA/tPSA, fPSA/cPSA ratios, tPSATZ and cPSATZ were significantly better predictors of repeat biopsy results than tPSA or cPSA, but there was no significant difference in the ROC curves among these four PSA parameters. In the multivariate logistic regression analysis these four PSA parameters were significant predictors for cancer detection in the repeat biopsy group (P < 0.001).

Conclusion: fPSA/tPSA ratio, fPSA/cPSA ratio, tPSATZ and cPSATZ enhance the specificity of PSA testing compared to tPSA or cPSA when determining which patients should undergo repeat biopsy.
Social learning in young‐of‐the‐year perch encountering a novel food type
Authors: Magnhagen C. , Staffan F.
Published: December 2004

Young‐of‐the‐year perch Perca fluviatilis were presented with a novel food type, dry feed, in the presence or absence of demonstrators, who were experienced to the feed. Most inexperienced fish lost mass in the beginning of the study, but untrained fish in the presence of demonstrators already had positive average growth during the first time period. There was a positive correlation between boldness and body mass change. Both social environment and individual characteristics thus seem to affect learning in perch.
Nursing experience in Iran
Authors: Nikbakht Nasrabadi Alireza , Emami Azita , Parsa Yekta Zohre
Published: December 2004

The aim of this study was to describe Iranian registered nurses’ experience of nursing, and to discuss some of the sociocultural viewpoints that are relevant for such experience. Data were collected by asking 75 registered nurses (RNs) to write statements about their nursing experience. Written descriptions were analyzed by an interpretative phenomenological method. Four different themes emerged: (i) task‐oriented nursing experience; (ii) caring‐oriented nursing experience; (iii) altruism‐oriented nursing experience; and (iv) difficulties experienced. Some participants explained nursing experience by describing a series of daily routine tasks. Others described experience by emphasizing how nursing was a caring profession, and some described their nursing experience from an altruistic viewpoint. Furthermore, the participants described nursing experience based on the relevant problems that they faced in everyday professional life. They expressed difficulties relating to work settings and also problems that were related to the sociocultural view of nursing in society. The nurses in general were dissatisfied with their work and this made them seriously consider leaving the nursing profession. The findings have implications for nursing management and education. These suggestions might enable changes that could effectively improve the status of nursing in Iran. An holistic approach is necessary to integrate these implications into a nursing system, both in practice and in education, for improving conditions that will facilitate a higher development of nursing in Iran.
Evidence for local production of antibodies to auto and non‐self antigens in periodontal disease
Authors: Rajapakse PS , Dolby AE
Published: December 2004

Autoimmune mechanisms may contribute to periodontal disease (PD) pathogenesis; autoantibody to collagentype 1 is produced at the periodontal site and local levels are found to be higher than in serum.

Objectives:  To find any evidence of autoimmune destruction in diseased periodontal tissues in patients with periodontitis. The study examines the relationship of antibodies to a self antigen collagen Type 1 and antigens from two periodontal pathogens namely Porphyromonas gingivalis (Pg), Actinobacillus actinomycetemcomitans (Aa) and a non‐oral bacterium Bacteroides fragilis (Bf) in disease sites and in serum.

Materials and methods:  Granulomatous tissues from periodontally diseased sites and serum samples were obtained from 13 patients (15 sites) undergoing surgical therapy. Tissues were homogenized at 4°C on Tris saline buffer [1 g (5 ml)−1], homogenate was centrifuged and the resultant supernatants were used in assays. Antibody to collagen and Aa, Pg and Bf in tissue eluates and serum were determined by competitive enzyme linked immunosorbant assay (ELISA) and conventional ELISA respectively using an alkaline phosphatase/p‐nitrophenyl phosphate enzyme‐substrate system. Sera from age and sex matched healthy subjects and pooled human serum were used as controls. Antibody (Ab) levels in tissues and serum were standardized by concomitant albumin assay.

Results:  Level of antibodies to collagen type 1 in tissue was significantly higher than in serum (P = 0.0001). Antibody levels in tissue to Pg were significantly higher than in serum (P = 0.0271). Ab levels to both Aa and Bf in tissues and serum were not significantly different from each other.

Conclusions:  These findings confirm the process of the local production of antibodies to autoantigen namely collagen type‐1 and to bacterial antigens in the granulomatous tissues housed within the periodontal lesions in patients with periodontitis.
Analyses of variable panoramic radiographic characteristics of maxillo‐mandibular fibrous dysplasia in McCune–Albright syndrome
Authors: Akintoye SO , Otis LL , Atkinson JC , Brahim J , Kushner H , Robey PG , Collins MT
Published: December 2004

Objective:  Fibrous dysplasia (FD) is a rare skeletal disease caused by activating GNAS1 gene mutations often found in association with the McCune–Albright syndrome (MAS). Multiple bones may be affected in FD, including maxilla and mandible. Patients with MAS have different endocrinopathies that can further influence bone metabolism. The purposes of this cross‐sectional study are to characterize FD panoramic radiographic patterns, and to evaluate the effects of age, endocrinopathies and renal phosphate wasting on radiographic characteristics of maxillo‐mandibular FD in MAS.

Subjects and methods:  Fifty‐one consecutive MAS patients were screened and panoramic radiographs of 43 patients with craniofacial FD were evaluated and analyzed for FD involvement. Clinical chemistries were evaluated for associations between radiographic patterns and age, endocrinopathies or renal phosphate wasting using Fisher's Exact Test.

Results:  Four types of radiographic changes were observed: ground glass (granular/condensed trabeculae), radiolucent (lytic), mixed radiolucent/radio‐opaque (mixed density) or radio‐opaque (sclerotic). Masking or displacement of the maxillary sinus (range: 77.8–86.4%) and mandibular canal (range: 55.6–75.0%) were prevalent in FD sites. Sixty‐three percent of the MAS patients had multiple dysregulated endocrine/metabolic functions, the most common were hyperthyroidism, precocious puberty and renal phosphate wasting. There were no statistically significant associations between radiographic patterns and age, endocrinopathies or renal phosphate wasting.

Conclusions:  Maxillo‐mandibular FD images in panoramic radiographs fall within a spectrum of four different patterns. Patients with facial asymmetry and any of these radiographic patterns should be promptly referred for further radiographic tests and endocrine evaluation if MAS is suspected.
Mucosal CD8α+ DC, with a plasmacytoid phenotype, induce differentiation and support function of T cells with regulatory properties
Authors: Bilsborough Janine , George Thaddeus C. , Norment Anne , Viney Joanne L.
Published: December 2004

Repetitive stimulation of naïve T cells by immature splenic dendritic cells (DC) can result in the differentiation of T‐cell lines with regulatory properties. In the present study we identified a population of DC in the mucosae that exhibit the plasmacytoid phenotype, secrete interferon‐α (IFN‐α) following stimulation with oligodeoxynucleotides containing certain cytosine‐phosphate‐guanosine (CpG) motifs and can differentiate naïve T cells into cells that exhibit regulatory properties. Although these DC appear to be present in both spleen and mesenteric lymph nodes (MLN), only CpG‐matured DC from the MLN (but not the spleen) were able to differentiate naïve T cells into T regulatory 1‐like cells with regulatory properties. The activity of these DC failed to sustain robust T‐cell proliferation and thereby enhanced the suppressive efficacy of CD4+ CD25+ T regulatory cells. These DC are the major CD8α+ DC population in the Peyer's patches (PP). Given their significant presence in mucosal tissue, we propose that these DC may provide a mechanistic basis for the homeostatic regulation in the gut by eliciting regulatory cell suppressor function and poorly supporting T helper cell proliferation at a site of high antigenic stimulation like the intestine.
Mitochondrial diversity evaluated by the single strand conformation polymorphism method in African and North American house flies (Musca domesticaL.)
Authors: Marquez J. G. , Krafsur E. S.
Published: December 2004

Single strand conformation polymorphisms (SSCPs) provide a convenient and inexpensive method of surveying mitochondrial genetic variation in large samples. We investigated how much variation should be incorporated into such surveys by scoring SSCP variation at eight mitochondrial loci in each of four sub‐Saharan African and four North American house fly (Diptera: Muscidae.) populations. Hierarchical analysis of diversity was performed on haplotype frequencies at each locus and on haplotype frequencies formed by combining haplotypes from two, three, four, five and eight loci. Composite haplotypes at two loci were as informative about population structure as those composed of a greater number of loci. Increasing the number of loci increased diversity estimates within, but not between, populations. Mean composite haplotype diversities (16S2andCOII) were 0.49 ± 0.09 among the African populations and 0.32 ± 0.08 among the North American populations. Only two of 16 haplotypes were shared between continents. Nei's genetic differentiation statistic between populations in continentsGPCwas 0.30 ± 0.06 and mean genetic differentiation between continentsGCTwas 0.39 ± 0.06. We conclude that there has been little detectable gene flow between North America and sub‐Saharan Africa.
Linkage and mapping analysis of a non‐susceptibility gene to densovirus (nsd‐2) in the silkworm, Bombyx mori
Authors: Ogoyi D. O. , Kadono‐Okuda K. , Eguchi R. , Furuta Y. , Hara W. , Nguu E. K. , Nagayasu K.
Published: December 2004

Nonsusceptibility to Bombyx mori densovirus type 2 (BmDNV‐2) is controlled by a recessive non‐susceptibility gene, nsd‐2 (non‐susceptibility to DNV‐2) in B. mori. Taking advantage of a lack of crossing over in females, reciprocal backcrossed F1 (BF1) progeny were used for linkage analysis and mapping of nsd‐2 using silkworm strains C124 and 902, which are classified as being highly susceptible and non‐susceptible to DNV‐2, respectively. BF1 larvae were inoculated twice with DNV‐2 virus at the first and second instar stages. DNA was extracted from each of the surviving fifth instar larvae and analysed by RFLP inheritance patterns using probes specific to each of the 28 linkage groups of B. mori. Our results indicated that the non‐susceptibility gene was linked to linkage group 17, since all surviving larvae showed the homozygous profile of strain 902 in their genotype. The other linkage groups showed mixtures of heterozygous and homozygous genotypes, indicating an independent assortment. A linkage map of 30.6 cM was constructed for linkage group 17 with nsd‐2 mapped at 24.5 cM and three closely linked cDNA markers were identified.
Substitution of a non‐retinal phospholipase C in Drosophila phototransduction
Authors: Kim S. , Chen D.‐M. , Zavarella K. , Fourtner C. F. , Stark W. S. , Shortridge R. D.
Published: December 2004

The Drosophila norpA gene encodes at least two subtypes of phospholipase C (PLC), one of which is essential for phototransduction and the other is utilized in signalling pathways other than phototransduction. The two subtypes of norpA‐PLC differ by 14 amino acids that have been proposed as important for the function of PLC in different signalling pathways. The present study aimed to determine whether norpA subtype II enzyme can functionally substitute for the subtype I enzyme in the phototransduction pathway. We found that the non‐retinal norpA‐PLC enzyme can substitute for its retinal counterpart, but that there is a reduced rate of repolarization of photoreceptors following intense light stimuli. This reduced repolarization might be due to the inability of a regulatory component being able to interact with the non‐retinal norpA‐PLC enzyme.
Molecular evolutionary analyses of mariners and other transposable elements in fire ants (Hymenoptera: Formicidae)
Authors: Krieger M. J. B. , Ross K. G.
Published: December 2004

Screens of a library of genomic DNA made during a recent study of the fire ant Solenopsis invicta revealed the presence of three distinct types of transposable elements (TEs). Two of the recovered sequences showed a high similarity to long‐terminal repeat (LTR) retrotransposons, while the third showed a high homology to mariner elements. To investigate the distribution and relationships of mariners in related ants, we PCR‐amplified these elements from additional Solenopsis species. Phylogenetic analyses showed that they form a single group within the mauritiana subfamily that is part of a larger clade derived from hymenopteran species. We also present partial sequence data for the two LTR‐retrotransposons and describe their phylogenetic affinities.