bluuebunny/crossref_metadata_2025_split huggingface dataset:
A porous‐matrix sensor to measure the matric potential of soil water in the field
Authors: Whalley W. R. , Clark L. J. , Take W. A. , Bird N. R. A. , Leech P. K. , Cope R. E. , Watts C. W. 
Published: March 2006

SummaryThe matric potential of soil water is probably the most useful assessment of soil water status. However, the water‐filled tensiometer (the benchmark instrument for measuring matric potential) typically only operates in the range 0 to −85 kPa. In this paper, we report the development of a porous‐matrix sensor to measure matric potential in the approximate range −50 to −300 kPa. The sensor uses a dielectric probe to measure the water content of a ceramic material with known water retention characteristics. The calculation of matric potential takes into account hysteresis through the application of an appropriate model to measured wetting and drying loops. It is important that this model uses closed, rather than open, scanning loops. The calibrated sensors were tested in the field and the output compared with data from water‐filled tensiometers and dielectric measurements of soil water content. These comparisons indicated that conventional tensiometers gave stable but false readings of matric potential when soil dried to matric potentials more negative than −80 kPa. The porous‐matrix sensors appeared to give reliable readings of matric potential in soil down to −300 kPa and also responded appropriately to repeated wetting and drying. This porous‐matrix sensor has considerable potential to help understand plant responses to drying soil.
Sorption of naphthalene derivatives on to soils from a long‐term field experiment: a particle size fractionation and extraction study
Authors: Novoszad M. , Gerzabek M. H. , Lischka H. , Haberhauer G. , Jakusch M. 
Published: March 2006

SummaryThe present work investigates the impact of site management on the retention of organic compounds in soil in a long‐term field experiment and focuses on the role of particle size fractions. Specifically, we studied the influence of long‐term farming practices on the soil’s ability to adsorb five hydrophobic organic compounds (HOCs), specifically naphthalene derivatives (naphthalene, 1‐naphthol, 1‐naphthylamine, 1‐hydroxy‐2‐naphthoic acid, 1,4‐naphthoquinone). We examined the sorption on soil and its particle‐size fractions with varying amounts and origins of organic matter in soil amended with farmyard manure and mineral fertilizers over more than 40 years. The soil organic matter had no significant impact on the sorption behaviour of the HOCs. Adsorption on the clay and silt fraction provided a deeper insight into the mechanisms and indicates a strong affinity with adsorption sites of the mineral phase. Naphthalene derivatives with hydrogen atoms in their functional groups adsorbed more strongly than other compounds on to soils containing smaller amounts of organic carbon. Desorption experiments with five organic extractants showed partitioning models for HOCs between extractant and soil surface. Only in experiments with the most polar extractant, formamide, did we observe an influence of the compound’s functional groups on the desorption mechanisms. Column experiments with a HPLC‐system and on‐line UV‐detection proved to be a satisfactory alternative to batch experiments. This approach should enable investigations of adsorption with larger numbers of compounds and soils at the same time.
Comparing the direct and community‐mediated effects of disturbance on plant population dynamics: flooding, herbivory and Mimulus guttatus
Authors: ELDERD BRET D. , DOAK DAN F. 
Published: March 2006

Summary
Competition, trophic interactions and abiotic disturbances play important roles in governing plant population dynamics, yet few studies have addressed their relative contributions or interacting effects.
We used Life Table Response Experiment (LTRE) analysis, coupled with stochastic analyses, to examine how a major abiotic disturbance, flooding, influences the fitness and population growth of a common riparian plant, Mimulus guttatus, and how this effect compares and interacts with that exerted by herbivory.
We also extended LTRE analysis to include nested factors, which enabled us to examine differences across experimental sites. These spatial contributions to changes in population growth rate, λ, were compared and contrasted with those derived for year and experimental treatments.
Flooding had direct positive impacts on population growth, while protection from herbivory benefited plants in both flooded and non‐flooded areas. Spatial variation in plant performance was also substantial, with greater variation across experimental sites than temporal variation across years.
Our stochastic analysis revealed that the impact of herbivores on population growth was much greater when the environment fluctuated between years with and without flooding than in more constant environments.
Both flooding and herbivory exerted the majority of their impacts on plant performance via changes in adult summer survival. For flooded sites, this was surprising, given the small difference in summer survival between control and herbivore‐exclusion treatments, and results from the high sensitivity of population growth to adult survival.
The importance of herbivory in flooded sites would have not been discerned had we not considered how adult survival interacts with other stages of the M. guttatus life cycle. Thus, in order to increase ecological understanding associated with shifts in community dynamics, experimental results should be placed in a life‐history context.
Within disturbance‐driven systems, the direct abiotic effects of factors such as flooding play a critical role in determining population dynamics. However, the biotic interactions that change as a consequence of disturbance can have equal and lasting impacts on population growth.
DNA polymerase X fromDeinococcus radioduranspossesses a structure‐modulated 3′→5′ exonuclease activity involved in radioresistance
Authors: Blasius Melanie , Shevelev Igor , Jolivet Edmond , Sommer Suzanne , Hübscher Ulrich 
Published: March 2006

SummaryRecently a family X DNA polymerase (PolXDr) was identified in the radioresistant bacteriumDeinococcus radiodurans. Knockout cells show a delay in double‐strand break repair (DSBR) and an increased sensitivity to γ‐irradiation. Here we show that PolXDrpossesses 3′→5′ exonuclease activity that stops cutting close to a loop. PolXDrconsists of a DNA polymerase X domain (PolXc) and a Polymerase and Histidinol Phosphatase (PHP) domain. Deletion of the PHP domain abolishes only the structure‐modulated but not the canonical 3′→5′ exonuclease activity. Thus, the exonuclease resides in the PolXc domain, but the structure‐specificity requires additionally the PHP domain. Mutation of two conserved glycines in the PolXc domain leads to a specific loss of the structure‐modulated exonuclease activity but not the exonuclease activity in general. The PHP domain itself does not show any activity. PolXDris the first family X DNA polymerase that harbours an exonuclease activity. The wild‐type protein, the glycine mutant and the two domains were expressed separately in ΔpolXDrcells. The wild‐type protein could restore the radiation resistance, whereas intriguingly the mutant proteins showed a significant negative effect on survival of γ‐irradiated cells. Taken together ourin vivoresults suggest that both PolXDrdomains play important roles in DSBR inD. radiodurans.
A bacterium that has three pathways to regulate membrane lipid fluidity
Authors: Cronan John E. 
Published: March 2006

SummaryWell‐studied bacteria such as Bacillus subtilis and Escherichia coli each have only a single pathway for synthesis of the unsaturated fatty acids required to make functional membrane lipids. In marked contrast, unsaturated fatty acid synthesis in Pseudomonas aeruginosa proceeds by three distinct pathways.
Analysis of the requirements for pilus biogenesis at the outer membrane usher and the function of the usher C‐terminus
Authors: Shu Kin So Stephane , Thanassi David G. 
Published: March 2006

SummaryUropathogenic strains of Escherichia coli assemble type 1 and P pili to colonize the bladder and kidney respectively. These pili are prototype structures assembled by the chaperone/usher secretion pathway. In this pathway, a periplasmic chaperone works together with an outer membrane (OM) usher to control the folding of pilus subunits, their assembly into a pilus fibre and secretion of the fibre to the cell surface. The usher serves as the assembly and secretion platform in the OM. The usher has distinct functional domains, with the N‐terminus providing the initial targeting site for chaperone–subunit complexes and the C‐terminus required for subsequent stages of pilus biogenesis. In this study, we investigated the molecular interactions occurring at the usher during pilus biogenesis and the function of the usher C‐terminus. We provide genetic and biochemical evidence that the usher functions as a complex in the OM and that interaction of the pilus adhesin with the usher is critical to prime the usher for pilus biogenesis. Analysis of C‐terminal truncation and substitution mutants of the P pilus usher PapC demonstrated that the C‐terminus is required for proper binding of chaperone–subunit complexes to the usher and plays an important role in assembly of complete pili.
Comparative immunology of human and animal models of hookworm infection
Authors: FUJIWARA R. T. , GEIGER S. M. , BETHONY J. , MENDEZ S. 
Published: March 2006

SUMMARY Hookworm infection is a major cause of disease burden for animals and humans. Over the past years, the use of animal models in hookworm infections has been driven by the search of new anthelminthic therapies and, especially, vaccine development. These studies also contributed to the advance of knowledge on immunity to hookworms, offering new insights to understand the nature of this parasitic infection. In this article, we will summarize the essential features of the immune response in the two major animal models of hookworm infections (dog and hamster) and then consider its implication for the human immune response.
In vitroinvestigation of ceruminolytic activity of various otic cleansers for veterinary use
Authors: Sánchez‐Leal J. , Mayós I. , Homedes J. , Ferrer L. 
Published: March 2006

AbstractKnowledge of the ceruminolytic activity of commercially available ear cleansing products assists the practitioner to choose the best available product for specific clinical situations. The aim of this study was to quantify and compare the ceruminolytic activity of commercially available canine ear cleansers. For this purpose, the ceruminolytic activity of 13 ear cleansers was evaluated using a standardized synthetic cerumen (SSC) that mimics the composition and texture of canine cerumen. The test products were incubated with mild agitation for 20 min with 500 mg of SSC previously compacted at the bottom of a test tube. Ceruminolytic activity was then assessed by quantifying the SSC removed by decantation. This procedure was repeated five consecutive times on each tube simulating repeated applications in the canine ear canal. Good repeatability among replicates was found in this assay, allowing direct comparisons between products. The final percentage of SSC elimination ranged from none (similar to water), between 8 and 39% for three products and up to 90% for one product (P < 0.001). It is concluded that, in the experimental conditions used in this study, only 1/13 products had significant ceruminolytic activity.
A trade‐off between sexual signalling and immune function in a natural population of the drumming wolf spider Hygrolycosa rubrofasciata
Authors: AHTIAINEN J. J. , ALATALO R. V. , KORTET R. , RANTALA M. J. 
Published: March 2006

AbstractThe field of ecological immunology is ultimately seeking to address the question ‘Why is there variation in immune function?’ Here, we provide experimental evidence that costs of ubiquitous sexual signals are a significant source of variation in immune function. In the mating season, males of the wolf spider Hygrolycosa rubrofasciata drum against dry leaves while wandering around the habitat searching for receptive females. According to a previous study, the male metabolic rate during the drumming increases 22‐fold compared to the resting metabolic rate. In the present study, we examined whether investment in costly courtship drumming decreases male immune function in a wild population of H. rubrofasciata. We induced males to increase their drumming rate by introducing females in proximity. As estimates of male immune function, we used lytic activity and encapsulation rate. Lytic activity estimates the concentration of antimicrobial peptides in haemolymph, which have been shown to play an important role in defence against bacteria, viruses and fungi. Encapsulation is an important defence mechanism against nematodes and insect parasitoids, but it also plays a role in defence against viruses. Our results show that males with nonarbitrarily increased investment in drumming rate had considerably lower lytic activities than control males. Also, there was a tendency for males with nonarbitrarily increased investment in drumming rate to have lower encapsulation rates than control males. This study provides experimental evidence for the first time, to our knowledge, that there are direct immunological costs of sexual signalling in natural populations. Therefore, immunological costs of sexual signals may provide significant phenotypic variation to parasite‐mediated sexual selection.
Restricted gene flow between two social forms in the ant Formica truncorum
Authors: GYLLENSTRAND N. , SEPPÄ P. , PAMILO P. 
Published: March 2006

AbstractWe studied genetic differentiation between two social forms (M‐type: single queen, independent nest founding; P‐type: multiple queens, dependent nest founding, building of colonial networks) of the ant Formica truncorum in a locality where the social types characterize two sympatric populations. The genetic results indicate restricted gene flow between the social forms. Female gene flow between the forms appears to be absent as they did not share mitochondrial haplotypes. Significant nuclear differentiation and the distribution of private alleles suggest that male gene flow between the forms is weak. However, the assignment analysis indicates some gene flow with P males mating with M females. The results have potentially important implications concerning social evolution within the forms but they need to be confirmed in other localities before they can be generalized. The colonies in the M‐type population have earlier been shown to produce split sex ratios, depending on the mating frequency of the queens. The inferred gene flow from the P to the M type means that the split sex ratio is partly suboptimal, possibly because the P populations are not long‐lived enough to influence the behavioural decisions in the M colonies.
Male sterility at extreme temperatures: a significant but neglected phenomenon for understanding Drosophila climatic adaptations
Authors: DAVID J. R. , ARARIPE L. O. , CHAKIR M. , LEGOUT H. , LEMOS B. , PÉTAVY G. , ROHMER C. , JOLY D. , MORETEAU B. 
Published: March 2006

AbstractThe thermal range for viability is quite variable among Drosophila species and it has long been known that these variations are correlated with geographic distribution: temperate species are on average more cold tolerant but more heat sensitive than tropical species. At both ends of their viability range, sterile males have been observed in all species investigated so far. This symmetrical phenomenon restricts the temperature limits within which permanent cultures can be kept in the laboratory. Thermal heat sterility thresholds are very variable across species from 23 °C in heat sensitive species up to 31 °C in heat tolerant species. In Drosophila melanogaster, genetic variations are observed among geographic populations. Tropical populations are more tolerant to heat induced sterility and recover more rapidly than temperate ones. A genetic analysis revealed that about 50% of the difference observed between natural populations was due to the Y chromosome. Natural populations have not reached a selection limit, however: thermal tolerance was still increased by keeping strains at a high temperature, close to the sterility threshold. On the low temperature side, a symmetrical reverse phenomenon seems to exist: temperate populations are more tolerant to cold than tropical ones. Compared to Mammals, drosophilids exhibit two major differences: first, male sterility occurs not only at high temperature, but also at a low temperature; second, sterility thresholds are not evolutionarily constrained, but highly variable. Altogether, significant and sometimes major genetic variations have been observed between species, between geographic races of the same species, and even between strains kept in the laboratory under different thermal regimes. In each case, it is easily argued that the observed variations correspond to adaptations to climatic conditions, and that male sterility is a significant component of fitness and a target of natural selection.
Serum testosterone levels using the radioimmunoassay method in healthy Japanese male volunteers
Authors: SATO YOSHIKAZU , TANDA HITOSHI , KATO SHUJI , ONISHI SHIGEKI , NAKAJIMA HISAO , NANBU AKIHITO , NITTA TOSHIKAZU , KOROKU MIKIO , AKAGASHI KEIGO , HANZAWA TATSUO , SHINOZAKI TADATOSHI , TERAO NAOAKI , FUJISAKI NOBUTA , KUWABARA MORIMASA , NIIMURA KENJI 
Published: March 2006

Aim:  The objective of the present study was to measure serum free and total testosterone values using the radioimmunoassay (RIA) method in healthy Japanese male volunteers with no current diseases.Methods:  Two hundred and fifty‐one healthy men who had no medical illness and received no current medical treatment were selected from 405 male volunteers. Free and total testosterone were measured in blood samples using the RIA method.Results:  Free but not total testosterone significantly decreased with age. Mean free testosterone values from morning blood samples for each age decade from the 20s to the 70s were 17.0, 14.6, 12.5, 10.6, 8.9 and 8.5 pg/mL, respectively. Mean total testosterone values from morning blood samples for each age decade from the 20s to the 70s were 4.7, 4.2, 4.4, 4.2, 4.2, 4.0 and 4.0 ng/mL, respectively. The rates of healthy volunteers that fell within the standard reference ranges for free and total testosterone were 97% and 97%, respectively. However, 19% of the total testosterone values were considered to indicate hypogonadism according to the International Society for the Study of the Aging Male (ISSAM) criteria (<3.17 ng/mL).Conclusions:  Our data corresponded to the standard reference ranges of Japanese men but not the ISSAM criteria. It may be more appropriate to establish a standard reference range for serum testosterone for individual countries. (Reprod Med Biol 2006; 5: 37–41)
Factors Influencing Voluntary Corporate Disclosure by Kenyan Companies
Authors: Barako Dulacha G. , Hancock Phil , Izan H. Y. 
Published: March 2006

There has been considerable research in respect of voluntary disclosure by companies and factors that may explain such disclosure. However, most of the research has been centred in developed countries. This study extends the previous literature by examining voluntary disclosure in a developing country, namely Kenya. Over the last decade, the Kenyan Government has initiated several far‐reaching reforms at the Nairobi Stock Exchange (NSE) in order to mobilise domestic savings and attract foreign capital investment. These measures include privatisation of state corporations through the stock exchange and allowing foreign investors to own shares in the listed companies. This study provides a longitudinal examination of voluntary disclosure practices in the annual reports of listed companies in Kenya from 1992 to 2001. The study investigates the extent to which corporate governance attributes, ownership structure and company characteristics influence voluntary disclosure practices.Our results suggest that the extent of voluntary disclosure is influenced by a firm's corporate governance attributes, ownership structure and company characteristics. The presence of an audit committee is a significant factor associated with the level of voluntary disclosure, and the proportion of non‐executive directors on the board is found to be significantly negatively associated with the extent of voluntary disclosure. The study also finds that the levels of institutional and foreign ownership have a significantly positive impact on voluntary disclosure. Large companies and companies with high debt voluntarily disclose more information. In contrast, board leadership structure, liquidity, profitability and type of external audit firm do not have a significant influence on the level of voluntary disclosure by companies in Kenya.
Disaster risk, climate change and international development: scope for, and challenges to, integration
Authors: Schipper Lisa , Pelling Mark 
Published: March 2006

AbstractReducing losses to weather‐related disasters, meeting the Millennium Development Goals and wider human development objectives, and implementing a successful response to climate change are aims that can only be accomplished if they are undertaken in an integrated manner. Currently, policy responses to address each of these independently may be redundant or, at worst, conflicting. We believe that this conflict can be attributed primarily to a lack of interaction and institutional overlap among the three communities of practice. Differences in language, method and political relevance may also contribute to the intellectual divide. Thus, this paper seeks to review the theoretical and policy linkages among disaster risk reduction, climate change and development. It finds that not only does action within one realm affect capacity for action in the others, but also that there is much that can be learnt and shared between realms in order to ensure a move towards a path of integrated and more sustainable development.
Financing climate change adaptation
Authors: Bouwer Laurens M. , Aerts Jeroen C.J.H. 
Published: March 2006

AbstractThis paper examines the topic of financing adaptation in future climate change policies. A major question is whether adaptation in developing countries should be financed under the 1992 United Nations Framework Convention on Climate Change (UNFCCC), or whether funding should come from other sources. We present an overview of financial resources and propose the employment of a two‐track approach: one track that attempts to secure climate change adaptation funding under the UNFCCC; and a second track that improves mainstreaming of climate risk management in development efforts. Developed countries would need to demonstrate much greater commitment to the funding of adaptation measures if the UNFCCC were to cover a substantial part of the costs. The mainstreaming of climate change adaptation could follow a risk management path, particularly in relation to disaster risk reduction. ‘Climate‐proofing’ of development projects that currently do not consider climate and weather risks could improve their sustainability.