Showing papers on "Literature survey published in 2005"

Exports and Productivity: A Survey of the Evidence from Firm Level Data

Abstract: While the role of exports in promoting growth in general, and productivity in particular, has been investigated empirically using aggregate data for countries and industries for a long time, only recently have comprehensive longitudinal data at the firm level been used to look at the extent and causes of productivity differentials between exporters and their counterparts which sell on the domestic market only. This paper surveys the empirical strategies applied, and the results produced, in 45 microeconometric studies with data from 33 countries that were published between 1995 and 2004. Details aside, exporters are found to be more productive than non-exporters, and the more productive firms self-select into export markets, while exporting does not necessarily improve productivity.

Host range and emerging and reemerging pathogens.

Abstract: An updated literature survey identified 1,407 recognized species of human pathogen, 58% of which are zoonotic. Of the total, 177 are regarded as emerging or reemerging. Zoonotic pathogens are twice as likely to be in this category as are nonzoonotic pathogens. Emerging and reemerging pathogens are not strongly associated with particular types of nonhuman hosts, but they are most likely to have the broadest host ranges. Emerging and reemerging zoonoses are associated with a wide range of drivers, but changes in land use and agriculture and demographic and societal changes are most commonly cited. However, although zoonotic pathogens do represent the most likely source of emerging and reemerging infectious disease, only a small minority have proved capable of causing major epidemics in the human population.

Expert system methodologies and applications—a decade review from 1995 to 2004

Abstract: This paper surveys expert systems (ES) development using a literature review and classification of articles from 1995 to 2004 with a keyword index and article abstract in order to explore how ES methodologies and applications have developed during this period. Based on the scope of 166 articles from 78 academic journals (retrieved from five online database) of ES applications, this paper surveys and classifies ES methodologies using the following eleven categories: rule-based systems, knowledge-based systems, neural networks, fuzzy ESs, object-oriented methodology, case-based reasoning, system architecture, intelligent agent systems, database methodology, modeling, and ontology together with their applications for different research and problem domains. Discussion is presented, indicating the followings future development directions for ES methodologies and applications: (1) ES methodologies are tending to develop towards expertise orientation and ES applications development is a problem-oriented domain. (2) It is suggested that different social science methodologies, such as psychology, cognitive science, and human behavior could implement ES as another kind of methodology. (3) The ability to continually change and obtain new understanding is the driving power of ES methodologies, and should be the ES application of future works.

Budgeting sinks and sources of CO2 in the coastal ocean: Diversity of ecosystems counts

Abstract: [1] Air-water CO2 fluxes were up-scaled to take into account the latitudinal and ecosystem diversity of the coastal ocean, based on an exhaustive literature survey. Marginal seas at high and temperate latitudes act as sinks of CO2 from the atmosphere, in contrast to subtropical and tropical marginal seas that act as sources of CO2 to the atmosphere. Overall, marginal seas act as a strong sink of CO2 of about −0.45 Pg C yr−1. This sink could be almost fully compensated by the emission of CO2 from the ensemble of near-shore coastal ecosystems of about 0.40 Pg C yr−1. Although this value is subject to large uncertainty, it stresses the importance of the diversity of ecosystems, in particular near-shore systems, when integrating CO2 fluxes at global scale in the coastal ocean.

Photodynamic therapy for periodontal diseases: state of the art.

Abstract: Background Photodynamic killing of periodontopathogenic bacteria may be an alternative to the systemic application of antibacterial drugs used in the treatment of periodontal diseases Even though the method is still in the experimental stage, increasing bacterial resistance problems may promote the introduction of photodynamic therapy (PDT) into periodontal practice Aim In this review a literature survey is given of PDT as seen from a periodontal perspective Methods In this review, the present knowledge and experience of PDT is summarized Literature data are presented on drawbacks of conventional antibiotics, the mechanism of PDT, bactericidal effects of PDT as well as results of clinical efforts The future prospects of the method are discussed Results The application of photosensitizing dyes and their excitation by visible light enables effective killing of periodontopathogens Encouraging studies using PDT in periodontitis and in peri-implantitis are known Conclusion Even though PDT is still in experimental stages of development and testing, the method may be an adjunct to conventional antibacterial measures in periodontology Clinical follow-up studies are needed to confirm the efficacy of the procedure

Facts and Myths about Research on Public Policy Implementation: Out-of-Fashion, Allegedly Dead, But Still Very Much Alive and Relevant

Abstract: Despite several decades of research on public policy implementation we know surprisingly little, not only about cumulative research results, but also about several other key aspects of this research field. This article tries to amend these deficiencies by presenting the results of a comprehensive literature survey. Its main purpose is to challenge, revise, and supplement some conventional wisdom about implementation research. A second motivation is to lay the foundation for and initiate a much needed synthesis of empirical research results. The main results are: The overall volume of publications on policy implementation has not stagnated or declined dramatically since the mid 1980s as is commonly asserted. On the contrary, it has continued to grow exponentially through the 1990s and into the twenty-first century. Even more surprising is that a large number of publications are located outside the core fields. Hence, the literature is substantially larger and more multidisciplinary than most commentators realize. Doctoral dissertations are the most ignored, but probably the richest, largest, and best source of empirical research results. Tracing the origin as well as the location of the disciplinary and geographical cradle of implementation studies must also be readjusted significantly. The ethnocentric bias of this research field toward the Western hemisphere has been, and still is, strong and some policy sectors are given much more attention than others. Although positive in many ways, the predominant multidisciplinary character of implementation research still poses some serious problems with respect to theory development. Thus, I discuss whether a resurgence of interest in policy implementation among policy scholars may already be occurring. Finally, I suggest that the time is long overdue for efforts to synthesize research results in a more rigorous scientific manner than has hitherto been done.

Sexual size dimorphism within species increases with body size in insects

Abstract: Studies examining interspecific differences in sexual size dimorphism (SSD) typically assume that the degree of sexual differences in body size is invariable within species. This work was conducted to assess validity of this assumption. As a result of a systematic literature survey, datasets for 158 insect species were retrieved. Each dataset contained adult or pupal weights of males and females for two or more different subsets, typically originating from different conditions during immature development. For each species, an analysis was conducted to examine dependence of SSD on body size, the latter variable being used as a proxy of environmental quality. A considerable variation in SSD was revealed at the intraspecific level in insects. The results suggest that environmental conditions may strongly affect the degree, though not the direction of SSD within species. In most species, female size appeared to be more sensitive to environmental conditions than male size: with conditions improving, there was a larger relative increase in female than male size. As a consequence, sexual differences in size were shown to increase with increasing body size in species with female-biased SSD (females were the larger sex in more than 80% of the species examined). The results were consistent across different insect orders and ecological subdivisions. Mechanisms leading to intraspecific variation in SSD are discussed. This study underlines the need to consider intraspecific variation in SSD in comparative studies.

A modeling framework for supply chain simulation: opportunities for improved decision-making

Abstract: Owing to its inherent modeling flexibility, simulation is often regarded as the proper means for supporting decision making on supply chain design. The ultimate success of supply chain simulation, however, is determined by a combination of the analyst's skills, the chain members' involvement, and the modeling capabilities of the simulation tool. This combination should provide the basis for a realistic simulation model, which is both transparent and complete. The need for transparency is especially strong for supply chains as they involve (semi)autonomous parties each having their own objectives. Mutual trust and model effectiveness are strongly influenced by the degree of completeness of each party's insight into the key decision variables. Ideally, visual interactive simulation models present an important communicative means for realizing the required overview and insight. Unfortunately, most models strongly focus on physical transactions, leaving key decision variables implicit for some or all of the parties involved. This especially applies to control structures, that is, the managers or systems responsible for control, their activities and their mutual attuning of these activities. Control elements are, for example, dispersed over the model, are not visualized, or form part of the time-indexed scheduling of events. In this article, we propose an alternative approach that explicitly addresses the modeling of control structures. First, we will conduct a literature survey with the aim of listing simulation model qualities essential for supporting successful decision making on supply chain design. Next, we use this insight to define an object-oriented modeling framework that facilitates supply chain simulation in a more realistic manner. This framework is meant to contribute to improved decision making in terms of recognizing and understanding opportunities for improved supply chain design. Finally, the use of the framework is illustrated by a case example concerning a supply chain for chilled salads.

A Critical Review of Twenty Years' Use of the Resource-Ratio Theory

Abstract: A model of species interactions based on their use of shared resources was proposed in 1972 by Robert MacArthur and later expanded in an article (1980) and a book (1982) by David Tilman. This "resource-ratio theory" has been used to make a num- ber of testable predictions about competition and community pat- terns. We reviewed 1,333 papers that cite Tilman's two publications to determine whether predictions of the resource-ratio theory have been adequately tested and to summarize their general conclusions. Most of the citations do not directly test the theory: only 26 studies provide well-designed tests of one or more predictions, resulting in 42 individual tests of predictions. Most of these tests were conducted in the laboratory or experimental microcosms and used primary producers in freshwater systems. Overall, the predictions of the resource-ratio theory were supported 75% of the time. One of the primary predictions of the model, that species dominance varies with ∗ .

H[∞] control and estimation of state-multiplicative linear systems

Abstract: Part I: Introduction and Literature Survey Introduction Part II: Continuous-time Systems Control and Luenberger-type Filtering General Filtering Tracking Control Static Output-feedback Stochastic Passivity Part III: Discrete-time Systems Control and Luenberger-type Filtering General Filtering Tracking Control Static Output-feedback Part IV: Applications Systems with State-multiplicative Noise: Applications Appendix A Introduction to Stochastic Differential Equations Appendix B The Continuous DLMI Method Appendix C The Discrete DLMI Method.

The Last Word on the Wage Curve

Abstract: Since 1990, there has been extensive international research on the responsiveness of wages of individuals to changing local labour market conditions. For many countries, an inverse relationship between wages and local unemployment rates has been found. In their book, The Wage Curve, Blanchflower and Oswald argued that the unemployment elasticity of pay is around -0.1 in most countries. In a 1995 literature survey, Card referred to this striking empirical regularity as being close to an 'empirical law of economics'. Nonetheless, reported elasticities do vary, even excluding outliers, between about -0.5 and +0.1. There is also considerable heterogeneity among wage curve studies in terms of data and model specification. This paper carries out meta-analytic techniques on a sample of 208 elasticities derived from the literature to uncover the reasons for the differences in empirical results across studies. Several causes of variation are identified. There is also clear evidence of downward publication bias. In addition, many reported t-statistics are biased upwards due to the use of aggregate unemployment rates. A maximum likelihood method and a trimming procedure are used to correct for these biases. Both methods give similar results for our sample. An unbiased estimate of the wage curve elasticity at the means of study characteristics is about -0.07.

Assessing connectivity of estuarine fishes based on stable isotope ratio analysis

Abstract: Assessing connectivity is fundamental to understanding the population dynamics of fishes. I propose that isotopic analyses can greatly contribute to studies of connectivity in estuarine fishes due to the high diversity of isotopic signatures found among estuarine habitats and the fact that variations in isotopic composition at the base of a food web are reflected in the tissues of consumers. Isotopic analysis can be used for identifying nursery habitats and estimating their contribution to adult populations. If movement to a new habitat is accompanied by a shift to foods of distinct isotopic composition, recent immigrants and residents can be distinguished based on their isotopic ratios. Movement patterns thus can be reconstructed based on information obtained from individuals. A key consideration is the rate of isotopic turnover, which determines the length of time that an immigrant to a given habitat will be distinguishable from a longtime resident. A literature survey indicated that few studies have measured turnover rates in fishes and that these have focused on larvae and juveniles. These studies reveal that biomass gain is the primary process driving turnover rates, while metabolic turnover is either minimal or undetectable. Using a simple dilution model and biomass-specific growth rates, I estimated that young fishes with fast growth rates will reflect the isotopic composition of a new diet within days or weeks. Older or slower-growing individuals may take years or never fully equilibrate. Future studies should evaluate the factors that influence turnover rates in fishes during various stages of the life cycle and in different tissues, as well as explore the potential for combining stable isotope and otolith microstructure analyses to examine the relationship between demographic parameters, movement and connectivity.

The interactive whiteboard: a literature survey

Abstract: There has been an increasing awareness of the need to understand the match between technology and pedagogy in the development of interactive learning supported by the interactive whiteboard in schools in the United Kingdom. There is evidence that teachers are seeking some understanding of the research background and to this end a team from Keele University has been working on three aspects of interactive whiteboard use – the management of change as the technology is introduced, the learning processes as teachers become more fluent with the hardware and software, and the development of interactivity as a feature of enhanced pedagogy. There is comparatively little background or research literature available but the team have sought this out and offer an analysis of findings from a broad sweep of sources. These confirm that enhanced interactivity requires an understanding of the way in which both teachers and pupils gain from the use of the technology and demonstrate that there is a progression at a...

The last word on the wage curve

Abstract: . Since 1990, there has been extensive international research on the responsiveness of wages of individuals to changing local labour market conditions. For many countries, an inverse relationship between wages and local unemployment rates has been found. In their book, The Wage Curve, Blanchflower and Oswald argued that the unemployment elasticity of pay is around −0.1 in most countries. In a 1995 literature survey, Card referred to this striking empirical regularity as being close to an ‘empirical law of economics’. Nonetheless, reported elasticities do vary, even excluding outliers, between about −0.5 and +0.1. There is also considerable heterogeneity among wage curve studies in terms of data and model specification. This paper carries out meta-analytic techniques on a sample of 208 elasticities derived from the literature to uncover the reasons for the differences in empirical results across studies. Several causes of variation are identified. There is also clear evidence of downward publication bias. In addition, many reported t-statistics are biased upwards due to the use of aggregate unemployment rates. A maximum likelihood method and a trimming procedure are used to correct for these biases. Both methods give similar results for our sample. An unbiased estimate of the wage curve elasticity at the means of study characteristics is about −0.07.

Naturally-occurring xanthones: recent developments.

Abstract: A literature survey covering the report of naturally occurring xanthones from January 2000 to December 2004, with 219 references, is presented in this review. Among 515 xanthones reported in this period, 278 were new natural xanthones. These xanthones have been identified from 20 families of higher plants (122 species in 44 genera), fungi (19 species) and lichens (3 species). The structural formulas of 368 identified xanthones, their distribution and a brief mention of their biological properties are also included.

Phylogenetic signal in AFLP data sets.

Abstract: AFLP markers provide a potential source of phylogenetic information for molecular systematic studies. However, there are properties of restriction fragment data that limit phylogenetic interpretation of AFLPs. These are (a) possible nonindependence of fragments, (b) problems of homology assignment of fragments, (c) asymmetry in the probability of losing and gaining fragments, and (d) problems in distinguishing heterozygote from homozygote bands. In the present study, AFLP data sets of Lactuca s.l. were examined for the presence of phylogenetic signal. An indication of this signal was provided by carrying out tree length distribution skewness (g1) tests, permutation tail probability (PTP) tests, and relative apparent synapomorphy analysis (RASA). A measure of the support for internal branches in the optimal parsimony tree (MPT) was made using bootstrap, jackknife, and decay analysis. Finally, the extent of congruence in MPTs for AFLP and internal transcribed spacer (ITS)-1 data sets for the same taxa was made using the partition homogeneity test (PHT) and the Templeton test. These analytical studies suggested the presence of phylogenetic signal in the AFLP data sets, although some incongruence was found between AFLP and ITS MPTs. An extensive literature survey undertaken indicated that authors report a general congruence of AFLP and ITS tree topologies across a wide range of taxonomic groups, suggesting that the present results and conclusions have a general bearing. In these earlier studies and those for Lactuca s.l., AFLP markers have been found to be informative at somewhat lower taxonomic levels than ITS sequences. Tentative estimates are suggested for the levels of ITS sequence divergence over which AFLP profiles are likely to be phylogenetically informative.

Brave Spirits on New Paths: Toward a Globally Relevant Paradigm of Indigenous Entrepreneurship Research

Abstract: This is the first study in a series aimed at strengthening research in the emerging field of Indigenous entrepreneurship. A literature survey revealed two dominant themes: the need to reconcile tradition with innovation and the need to understand how Indigenous world-views and values impact upon enterprise. Four relevant theoretical contexts guided an empirical investigation employing depth interviews with 40 selected opinion leaders representing two cultures: Indigenous Australian and American Indian. Data evaluation culminated in the formal articulation of a paradigm for Indigenous entrepreneurship research. Discussion focused on utility of the paradigm and future research directions.

Biological Variation of Total Prostate-Specific Antigen: A Survey of Published Estimates and Consequences for Clinical Practice

Abstract: Background: The objectives of this study were to determine whether a single result for total prostate-specific antigen (tPSA) can be used confidently to guide the need for prostate biopsy and by how much serial tPSA measurements must differ to be significant. tPSA measurements include both analytical and biological components of variation. The European Group on Tumor Markers conducted a literature survey to determine both the magnitude and impact of biological variation on single, the mean of replicate, and serial tPSA measurements. Methods: The survey yielded 27 studies addressing the topic, and estimates for the biological variation of tPSA could be derived from 12 of these studies. Results: The mean biological variation was 20% in the concentration range 0.1–20 μg/L for men over 50 years. The biological variation means that the one-sided 95% confidence interval (CI) of the dispersion for a single tPSA result is ∼33%. Three replicate samples with one analysis on each narrow the one-sided 95% CI for the mean concentration to ∼20% and facilitate decisions on prostate biopsy. During monitoring of serial measurements, the change needed for significance is ∼50% ( P <0.05). Conclusions: The biological variation of tPSA has implications for screening, diagnosis, and monitoring. Single measurements may not be sufficiently precise for screening and diagnosis. Replicate samples and calculation of the mean concentration may improve precision by reducing the dispersion. Monitoring of tPSA requires an estimate of either the change needed for significance or, alternatively, of the significance of the change.

Genotoxicity of environmental agents assessed by the alkaline comet assay

Abstract: Generation of DNA damage is considered to be an important initial event in carcinogenesis. A considerable battery of assays exists for the detection of different genotoxic effects of compounds in experimental systems, or for investigations of exposure to genotoxic agents in environmental or occupational settings. Some of the tests may have limited use because of complicated technical setup or because they only are applicable to a few cell types. The single cell gel electrophoresis (comet) assay is technically simple, relatively fast, cheap, and DNA damage can be investigated in virtually all mammalian cell types without requirement for cell culture. The aim of this thesis was to evaluate the comet assay as a genotoxicity test in genetic toxicology of environmental agents, encompassing both experimental animal models and biomonitoring. The comet assay detects strand breaks (SB). The cells are embedded in agarose and lysed, generating nucleus-like structures in the gel (referred to as nucleoids). Following alkaline electrophoresis, the DNA strands migrate toward the anode, and the extent of migration depends on the number of SB in the nucleoid. The migration is visualized and scored in a fluorescence microscope after staining. Broad classes of oxidative DNA damage can be detected as additional SB if nucleoids are incubated with bacterial DNA glycosylase/endonuclease enzymes. Oxidized pyrimidines and purines can be detected by incubation with endonuclease III and formamidopyrimidine DNA glycosylase, respectively. The animal experimental studies indicated that the comet assay was able to detect genotoxic effects of diesel exhaust particles in lung tissue, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)-induced DNA damage in colon epithelial cells and liver tissue, and benzene-induced damage in bone marrow and liver cells. The strength of the comet assay was further outlined by application of repair enzymes, indicating no oxidative DNA base damage following IQ treatment. High levels of oxidative DNA lesions were detected after exposure to benzene or X-ray irradiation. The comet assay did not detect DNA damage in colon or liver following ingestion of diets containing of high contents of animal fat or sucrose, although other indices of DNA damage were found. Determined from the results of a large Japanese study, the discrimination between carcinogens and non-carcinogens appears to be similar between the comet assay and alkaline elution, which also detects SB. This suggests that the comet assay is a reliable genotoxicity test in animal experimental systems. In the biomonitoring studies, we investigated the effect of common exposures and lifestyle factors (rather than effects of known carcinogens) on the level of oxidative DNA damage in mononuclear blood cells of humans. In the first study, based on repeated measurements, it was shown that interindividual variation and seasonal variation were major determinants for the basal level of SB, whereas no effect of age, exercise, or antioxidant intake could be detected. The effect of exercise was further investigated under both normoxic and hypoxic circumstances, showing a strong effect of hypoxia, and only effect of exercise in terms of SB in hypoxia. In a placebo-controlled parallel dietary fruit and vegetable (or the corresponding amount of antioxidants) intervention study, no effects of the level of oxidative DNA damage or sensitivity to hydrogen peroxide were observed. Although this may seem in contrast to other antioxidant intervention studies, a critical literature survey of antioxidant intervention studies on oxidative DNA damage suggested that well-controlled studies tended to show no effect of antioxidant supplementation. In summary, the aggregated data from the publications included in this thesis, and other publications encompassing the comet assay, indicate that the comet assay is a reliable method for detection of DNA damage in tissues of experimental animals. Although not all types of genotoxic exposures should be expected to result in DNA damage in mononuclear blood cells, the comet assay seems to be a valuable tool for detection of genotoxic exposure in humans. The comet assay indicates that DNA damage is abundant in mammalian cells and affected by lifestyle and many environmental exposures, including diet, exercise, hypoxia, and sunlight.

Removal of Enteric Bacteria in Constructed Treatment Wetlands with Emergent Macrophytes: A Review

Abstract: Domestic and municipal sewage contains various pathogenic or potentially pathogenic microorganisms which, depending on species concentration, pose a potential risk to human health and whose presence must therefore be reduced in the course of wastewater treatment. The removal of microbiological pollution is seldom a primary target for constructed treatment wetlands (CWs). However, wetlands are known to act as excellent biofilters through a complex of physical, chemical and biological factors which all participate in the reduction of the number of bacteria. Measurement of human pathogenic organisms in untreated and treated wastewater is expensive and technically challenging. Consequently, environmental engineers have sought indicator organisms that are (1) easy to monitor and (2) correlate with population of pathogenic organisms. The most frequently used indicators are total coliforms, fecal coliforms, fecal streptococci and Escherichia coli. The literature survey of 60 constructed wetlands with emergent vegetation around the world revealed that removal of total and fecal coliforms in constructed wetlands with emergent macrophytes is high, usually 95 to > 99% while removal of fecal streptococci is lower, usually 80-95%. Because bacterial removal efficiency is a function of inflow bacteria number, the high removal effects are achieved for untreated or mechanically pretreated wastewater. Therefore, the outflow numbers of bacteria are more important. For TC and FC the outflow concentrations are usually in the range of 10(2) to 10(5) CFU/ 100 ml while for FS the range is between 10(2) and 10(4) CFU/ 100 ml. Results from operating systems suggest that enteric microbe removal efficiency in CWs with emergent macrophytes is primarily influenced by hydraulic loading rate (HLR) and the resultant hydraulic residence time (HRT) and the presence of vegetation. Removal of enteric bacteria follows approximately a first-order relationship.

Review of the plants with anti-inflammatory activity studied in Brazil

Abstract: The inflammatory reaction is a response of the organism against an injury and it involves the action of complex events and mediators through of the blood vessels. The present work is a literature survey of the extracts of plants with anti-inflammatory activity studied in Brazil. The review refers to 75 plants with their families, parts used, type of extract used, bioassay models and their activity.

Unification and evaluation of equalization structures and design algorithms for discrete multitone modulation systems

Abstract: To ease equalization in a multicarrier system, a cyclic prefix (CP) is typically inserted between successive symbols. When the channel order exceeds the CP length, equalization can be accomplished via a time-domain equalizer (TEQ), which is a finite impulse response (FIR) filter. The TEQ is placed in cascade with the channel to produce an effective shortened impulse response. Alternatively, a bank of equalizers can remove the interference tone-by-tone. This paper presents a unified treatment of equalizer designs for multicarrier receivers, with an emphasis on discrete multitone systems. It is shown that almost all equalizer designs share a common mathematical framework based on the maximization of a product of generalized Rayleigh quotients. This framework is used to give an overview of existing designs (including an extensive literature survey), to apply a unified notation, and to present various common strategies to obtain a solution. Moreover, the unification emphasizes the differences between the methods, enabling a comparison of their advantages and disadvantages. In addition, 16 different equalizer structures and design procedures are compared in terms of computational complexity and achievable bit rate using synthetic and measured data.

Sex ratio patterns in dioicous bryophytes re-visited

Abstract: Based on a literature survey and our own investigations of selected species, we present a compilation of expressed sex ratios in 103 taxa of dioicous bryophytes, including 56 mosses and 47 liverworts. We grouped the approaches used to determine sex into two categories: (1) sex assessment per herbarium specimen or per patch in the field; (2) sex assessment by examination of individual shoots or thalli, usually in the field. Eighty-eight per cent of the taxa studied by the former methods, and 68% of those included in the latter, exhibited a female-biased sex ratio. The F : M values varied by a factor of 46 among species, excluding cases with only one sex expressing. There was also within-species variation of sex expression and ratio related to geographical area, altitude, year, substratum, plant maturity, and compared with cultivation conditions, and between the two method categories. Across taxa, proportions of non-expressing and sporophytic samples were negatively related to each other; however, t...