bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency-dependent success of aggressive mimics in a cleaning symbiosis
Authors: Cheney Karen L , Côté Isabelle M
Published: October 2005

Batesian mimics—palatable organisms that resemble unpalatable ones—are usually maintained in populations by frequency-dependent selection. We tested whether this mechanism was also responsible for the maintenance of aggressive mimicry in natural populations of coral reef fishes. The attack success of bluestriped fangblennies (
Plagiotremus rhinorhynchos
), which mimic juvenile bluestreaked cleaner wrasses (
Labroides dimidiatus
) in colour but tear flesh and scales from fishes instead of removing ectoparasites, was frequency-dependent, increasing as mimics became rarer relative to their model. However, cleaner mimics were also more successful on reefs with higher densities of potential victims, perhaps because a dilution-like effect creates few opportunities for potential victims to learn to avoid mimics. Further studies should reveal whether this second mechanism is specific to aggressive mimicry.
Non-random nature of spontaneous mIPSCs in mouse auditory brainstem neurons revealed by recurrence quantification analysis
Authors: Leao Richardson N , Leao Fabricio N , Walmsley Bruce
Published: October 2005

A change in the spontaneous release of neurotransmitter is a useful indicator of processes occurring within presynaptic terminals. Linear techniques (e.g. Fourier transform) have been used to analyse spontaneous synaptic events in previous studies, but such methods are inappropriate if the timing pattern is complex. We have investigated spontaneous glycinergic miniature synaptic currents (mIPSCs) in principal cells of the medial nucleus of the trapezoid body. The random versus deterministic (or periodic) nature of mIPSCs was assessed using recurrence quantification analysis. Nonlinear methods were then used to quantify any detected determinism in spontaneous release, and to test for chaotic or fractal patterns. Modelling demonstrated that this procedure is much more sensitive in detecting periodicities than conventional techniques. mIPSCs were found to exhibit periodicities that were abolished by blockade of internal calcium stores with ryanodine, suggesting calcium oscillations in the presynaptic inhibitory terminals. Analysis indicated that mIPSC occurrences were chaotic in nature. Furthermore, periodicities were less evident in congenitally deaf mice than in normal mice, indicating that appropriate neural activity during development is necessary for the expression of deterministic chaos in mIPSC patterns. We suggest that chaotic oscillations of mIPSC occurrences play a physiological role in signal processing in the auditory brainstem.
Genome size and metabolic intensity in tetrapods: a tale of two lines
Authors: Vinogradov Alexander E , Anatskaya Olga V
Published: October 2005

We show the negative link between genome size and metabolic intensity in tetrapods, using the heart index (relative heart mass) as a unified indicator of metabolic intensity in poikilothermal and homeothermal animals. We found two separate regression lines of heart index on genome size for reptiles–birds and amphibians–mammals (the slope of regression is steeper in reptiles–birds). We also show a negative correlation between GC content and nucleosome formation potential in vertebrate DNA, and, consistent with this relationship, a positive correlation between genome GC content and nuclear size (independent of genome size). It is known that there are two separate regression lines of genome GC content on genome size for reptiles–birds and amphibians–mammals: reptiles–birds have the relatively higher GC content (for their genome sizes) compared to amphibians–mammals. Our results suggest uniting all these data into one concept. The slope of negative regression between GC content and nucleosome formation potential is steeper in exons than in non-coding DNA (where nucleosome formation potential is generally higher), which indicates a special role of non-coding DNA for orderly chromatin organization. The chromatin condensation and nuclear size are supposed to be key parameters that accommodate the effects of both genome size and GC content and connect them with metabolic intensity. Our data suggest that the reptilian–birds clade evolved special relationships among these parameters, whereas mammals preserved the amphibian-like relationships. Surprisingly, mammals, although acquiring a more complex general organization, seem to retain certain genome-related properties that are similar to amphibians. At the same time, the slope of regression between nucleosome formation potential and GC content is steeper in poikilothermal than in homeothermal genomes, which suggests that mammals and birds acquired certain common features of genomic organization.
Thermodynamic conditions for stability in materials with rate-independent dissipation
Authors: Petryk Henryk
Published: October 2005

A distinctive feature of the examined class of solids is that a part of the entropy production is due to rate-independent dissipation, as in models of plasticity, damage or martensitic transformations. The standard condition for thermodynamic stability is shown to be too restrictive for such solids and, therefore, an extended condition for stability of equilibrium is developed. The classical thermodynamic theory of irreversible processes is used along with the internal variable approach, with the emphasis on the macroscopic effects of micro-scale instabilities in the presence of two different scales of time. Specific conditions for material stability against internal structural rearrangements under deformation-sensitive loading are derived within the incremental constitutive framework of multi-mode inelasticity. Application to spontaneous formation of deformation bands in a continuum is presented. Conditions for stability or instability of a quasi-static process induced by varying loading are given under additional constitutive postulates of normality and symmetry. As illustration of the theory, the stability of equilibrium or a deformation path under uniaxial tension is analysed for a class of inelastic constitutive laws for a metal crystal deformed plastically by multi-slip or undergoing stress-induced martensitic transformation.
Thermodynamically consistent relations involving plasticity, internal energy and thermal effects
Authors: Schreyer H.L , Maudlin P.J
Published: October 2005

Experimental data associated with plastic deformations indicate that the temperature is less than that predicted from dissipation based on plastic work. To obtain reasonable correlation between theoretical and experimental results, the plastic work is often multiplied by a constant
β
. This paper provides an alternative thermodynamic framework in which it is proposed that there is an additional internal energy associated with dislocation pile-up or increase in dislocation density. The form of this internal energy follows from experimental data that relates flow stress to dislocation density and to equivalent plastic strain. The result is that
β
is not a constant but a derived function. Representative results for
β
and temperature as functions of effective plastic strain are provided for both an uncoupled and a coupled thermoplastic theory. In addition to providing features that are believed to be representative of many metals, the formulation can be used as a basis for more advanced theories such as those needed for large deformations and general forms of internal energy.
Body pigmentation pattern to assess introgression by hatchery stocks in native Salmo trutta from Mediterranean streams
Authors: Aparicio E. , García‐Berthou E. , Araguas R. M. , Martínez P. , García‐Marín J. L.
Published: October 2005

Five qualitative and seven quantitative colouration and spotting pattern features were measured in 23 brown trout Salmo trutta populations and two hatchery stocks. Simultaneously, the LDH‐C1*, a diagnostic locus fixed for *90 and *100 alleles in stocking and native populations from southern Europe, respectively, was analysed to classify the brown trout studied according to their origin: native, hatchery stock and hybrids. The three genotypes showed significant differences in the colouration and spotting features and a discriminant function analysis could correctly identify 79% of the individuals. The most discriminating variables were dorsal fin margin colour, number of opercular spots, presence of the preopercular mark and diameter of black spots. Given the low cost, ease and possibility of field identification of native fish, the results indicate great opportunities for the application of morphological‐based classification models on the conservation and management of native brown trout stocks.
Optimization of fertilization success in Sander vitreus is influenced by the sperm : egg ratio and ova storage
Authors: Rinchard J. , Dabrowski K. , Van Tassell J. J. , Stein R. A.
Published: October 2005

Walleye Sander vitreum eggs could be stored at 7° C for up to 30 h with 60% fertilization rates. Fertilization rates at 1 and 12° C fell to 17 and 5%, respectively. At spermatozoa : egg ratios <25 000 : 1, survival to the eyed stage declined precipitously. Beyond a ratio of 25 000 : 1, survival to the eyed stage did not increase >c. ∼ 70%. Therefore, a standard spermatozoa : egg ratio of 25 000 : 1 was established and is recommended for studies concerning fertilizing success.
Genetic identification of members of the Phoxinus eos‐neogaeus hybrid complex
Authors: Binet M.‐C. , Angers B.
Published: October 2005

In order to identify the several biotypes of the Phoxinus eos‐neogaeus hybrid complex that can be found in sympatry with either or both parental species, a PCR based method was developed. This allowed identification of the mitochondrial genome and determination of the composition and the ploidy of the nuclear genome.
DNA identification of gut contents of large pelagic fishes
Authors: Smith P. J. , Mcveagh S. M. , Allain V. , Sanchez C.
Published: October 2005

Partially digested prey items taken from the gut contents of seven species of large pelagic fishes were identified by DNA sequencing of part of the cytochrome b gene. Sequences matched against those of five pelagic prey species held in GenBank® with 99–100% identities. The method is applicable to most gut content identifications, the only limiting factor being the range of control species sequences held in the reference database.
Comparative mtDNA sequence (control region, ATPase 6 and NADH‐1) divergence in Hucho taimen(Pallas) across four Siberian river basins
Authors: Froufe E. , Alekseyev S. , Knizhin I. , Weiss S.
Published: October 2005

Hucho taimen from eight populations spanning four drainage basins (Amur, Lena, Enisei and Khatanga) were analysed for nucleotide sequence variation across three mitochondrial genes (ATP6, NADH‐1 and control region). Samples of H. hucho, Brachymystax lenok(sharp‐snouted and blunt‐snouted forms) and Parahucho perryi were also included for comparison. Nucleotide variation across a total of 1826 base pairs in H. taimen revealed shared haplotypes between the Amur and Lena basins, further supporting a previous hypothesis of late to post‐Pleistocene hydrological exchange between these now disjunct basins. In contrast to an earlier study using the control region alone, clear phylogeographic structure was seen at a large geographic scale, reflected by two phylogroups, one corresponding to the Amur and Lena basins, and the other to the Enisei and Khatanga basins. Comparative rates of divergence revealed considerably faster and less heterogeneous substitution rates for the two coding genes, especially at interspecific levels compared to the mtDNA control region.
A histological study on the development of the digestive system of Pseudosciaena crocea larvae and juveniles
Authors: Mai K. , Yu H. , Ma H. , Duan Q. , Gisbert E. , Infante J. L. Zambonino , Cahu C. L.
Published: October 2005

The ontogenetic development of the gut and accessory organs in large yellow croaker Pseudosciaena crocea was investigated using light microscopy from hatching up to the juvenile stage (40 days post hatch, dph). At 3 dph (mean ± s.d., 4·1 ± 0·1 mm total length, LT), coinciding with the buccopharynx opening, larvae started to feed exogenously, and the gut consisted of a well‐developed buccopharynx, a partially‐differentiated oesophagus and an intestine divided in three regions (anterior intestine, intermediate intestine and rectum). Yolk reserves were not completely depleted at the onset of exogenous feeding, and a period of mixed nutrition was observed up to 6 dph (4·3 ± 0·1 mm LT), when yolk was definitively exhausted. Important morphological changes occurred at the end of the larval period, coinciding with metamorphosis. At 17 dph (6·8 ± 0·6 mm LT), pyloric caeca differentiated at the junction of the pyloric stomach and the anterior intestine. Gastric glands were first observed at 21 dph (9·2 ± 1·2 mm LT), coinciding with the morphological development of the stomach in three different regions (cardiac, fundic and pyloric) according to the histological characteristics of their mucosa. At this age, large longitudinal folds appeared in the median and posterior oesophageal mucosa. These morphological and histological features suggested the achievement of a digestive system characteristic of large yellow croaker juveniles and adults.
Moral problems and distress among nurse practitioners in primary care
Authors: Laabs Carolyn A.
Published: October 2005

Purpose

To identify the ethical issues nurse practitioners (NPs) encounter in primary care, examine the types of moral problems that arise related to those issues, and determine the level of distress NPs experience.

Data source

Self‐reported responses to an investigator‐designed, anonymous, mailed survey on a convenience sample of 71 NPs practicing in primary care in one midwestern metropolitan area.

Conclusions

This preliminary descriptive study identified a number and variety of ethical issues NPs encounter in primary care. The issue encountered with the greatest frequency was patient refusal of appropriate treatment. Distress was reported most often over problems of moral dilemma, followed by moral distress, and least often, moral uncertainty and moral outrage. Another type of moral problem, possibly related to conflict between patient autonomy and NP beneficence, occurred almost as often as moral dilemma. Not as many NPs reported encountering ethical issues or being distressed as the literature suggests. The reason for this is unclear but may be related to NPs’ sense of moral responsibility or their ability to discern subtle ethical issues in the complex primary care environment. Regardless of moral problem, NPs felt frustrated and powerless. As a result, some changed jobs and contemplated leaving advanced practice.

Implications for practice

More research is needed to clearly understand ethical issues and moral problems for NPs in primary care, how NPs identify and manage problems, and the effects on NPs and patients.
Surface Area Reduction During Isothermal Sintering
Authors: GERMAN R. M. , MUNIR Z. A.
Published: October 2005

A kinetic model for the reduction in specific surface area during isothermal sintering is examined in detail. Experimental data for a variety of materials including A12O3, B, Ni, Cu, ZnO, TiO2, Fe2O3, and As‐Se‐S glasses are analyzed by the technique provided. The results of this technique agree well with those for previously identified sintering mechanisms for each material. The kinetic model is based on sintering driven by the curvature gradient in the interparticle neck region associated with initial‐stage sintering. At the intermediate stage of sintering, a diminished curvature gradient shifts the sintering driving force to the excess surface free energy.
Effect of Carbon and Water on Wetting and Reactions of B2O3‐Containing Glasses on Platinum
Authors: HOLMQUIST GLENN A. , PASK JOSEPH A.
Published: October 2005

Sessile‐drop experiments were conducted to analyze the wetting characteristics of molten B2O3 and B2O3‐containing glasses on Pt. In atmospheres free of carbonaceous gases, the contact angle for all glasses on Pt was small and invariant under ambient pressures of 10‐4 torr to 1 atm for the range 700° to 1000°C. Adsorption of carbon at the metal surface decreased the solid/vapor surface energy and increased the contact angle. Carbon was removed by oxidation at a specific ambient pressure, resulting in a reduction in the contact angle. Temperature‐pressure data are reported for Pt. Absorption of water vapor by the glasses resulted in a reaction at the solid/liquid interface, spreading of the glass, and adherence. The possible reactions that can occur are given.
Dielectric Behavior of Lead‐Silicate Glasses Containing Iron
Authors: EL‐BAYOUMI OSAMA H. , MAcCRONE R. K.
Published: October 2005

The ac conductivity of lead‐silicate glasses containing Fe was measured in the range 4.5° to 500° K to investigate the electronic hopping mechanism in these amorphous materials. Classes containing 0.0, 2.0, and 10.0 wt% Fe2O2 were prepared under normal atmospheric conditions. The ac conductivity, which increased with increasing Fe concentration, followed an Arrhenius expression at the higher temperatures. The activation energy for ac conduction increased with increasing Fe concentration, in contrast to the usual decrease in activation energy observed by other workers. The frequency of the conductivity σ(ω)was approximately of the form σ (ω)αω‐n where the exponent increases with increasing Fe concentration and temperature. This behavior is explained by assuming that a distribution of hopping distances and activation energies is involved in the ac electron transport mechanism. At low temperatures, the curves for tanδ vs Tfor all samples showed a broad relaxation peak at ∼ 70°K. Although this peak is frequency‐dependent, it was independent of Fe concentration. The results did not indicate electron hopping between localized states in the temperature range studied.
Oxidation of Si3N4 in the Range 1300° to 1500°C
Authors: TRIPP W. C. , GRAHAM H. C.
Published: October 2005

The isothermal oxidation behavior of commercial hot‐pressed Si3N4 was evaluated for temperatures from 1300° to 1500°C. Multiphase scales were formed, consisting mainly of α‐cristobalite and enstatite. A large increase in reaction rate above 1450°C is believed to be caused by melting in the scale and the consequent increase in the rate of oxygen transport. No oxygen pressure dependence was observed at 1400°C over the oxygen pressure range 10‐9 atm to 600 torr. However, a small decrease in the kinetics was observed when measurements were made in reduced total pressures of oxygen as compared to O2/N2mixtures at a constant total pressure.
An Error Analysis of Failure Prediction Techniques Derived From Fracture Mechanics
Authors: WIEDERHORN S. M. , FULLER E. R. , MANDEL J. , EVANS A. G.
Published: October 2005

Three principal methods of failure prediction for brittle materials are analyzed statistically. Each method depends on fracture mechanics for its predictive value; hence the variance of the failure time depends on the scatter in the fracture mechanics data and the scatter in the estimate of the initial size of the strength‐limiting crack. The variance is used to calculate confidence limits for the prediction of failure for glass and SiC. Procedures for the collection and analysis of data are discussed and the implications of the analysis for lifetime prediction are evaluated.
Interdiffusion in the System SrF2‐BaF2
Authors: SCHEIDECKER R. W. , BERARD M. F.
Published: October 2005

A microprobe study of interdiffusion between 1033° and 1238°C in the system SrF2‐BaF2 was conducted using single crystals. The interdiffusion coefficient, D, generally decreased with increasing SrF2 concentration, but the composition dependence of D decreased with decreasing temperature. Extrapolation of D values to infinite dilution allowed the impurity cation self‐ diffusion coefficients:

image

The values for DSr in BaF2 are in excellent agreement with tracer results. An analysis of the activation energies for cations diffusing in alkaline‐earth fluorides shows a direct correlation between constriction ratio and migration energy for a single ion diffusing in different fluorides. An apparent anomaly arises when attempting to correlate migration energy with structural information for different cations diffusing in the same fluoride.
Microwave‐Absorbing Ferrite‐Dielectric Composites
Authors: MAGUIRE E. A. , READEY D. W.
Published: October 2005

Two‐phase composites of spinel ferrites and lithium aluminosilicates were prepared and investigated as microwave‐absorbing materials. The magnetic and dielectric loss parameters which determine the heating characteristics were examined. Low‐thermal‐expansion composites were developed which were effective absorbers of microwave radiation. Some compositions investigated exhibited a temperature maximum limited by the Curie temperature of the ferrite in the composite.
Controlled Surface Flaw‐Initiated Fracture in Reaction‐Densified Silicon Carbide
Authors: WILLS R. R. , WIMMER J. M.
Published: October 2005

Controlled surface flaws were produced in commercial reaction‐densified SiC by Knoop microhardness indentation. The flaws themselves could not be observed easily, thus an etching technique was used to delineate their semielliptical shape, thereby enabling calculation of the critical stress‐ intensity factor KIC at room temperature. Room‐temperature fracture was insensitive to annealing environment (air or vacuum), flaw “healing” being observed at ≫1000°C. The variation in fracture stress of indented specimens with temperature showed 3 distinct regions of behavior which were interpreted in terms of residual stress relief, flaw healing, and Si‐SiC bond weakening.
Stress Analysis of Large Deflection of Glass Plates by the Finite‐Element Method
Authors: TSAI CHENGLUNG R. , STEWART ROBERT A.
Published: October 2005

A computer program is used in analyzing stress and deflection characteristics of plates undergoing large deflection. Experimental data were obtained for glass plates with different area, aspect ratio, and thickness subjected to simulated windload. The theoretical predictions and test data are correlated herein and show excellent agreement.
Application of Transmission Electron Microscopy to the Study of Deformation in Ceramic Oxides
Authors: MITCHELL T. E.
Published: October 2005

Slip systems, dislocation reactions, and dislocation dissociations are reviewed in relation to the crystal structures of ceramic oxides. Techniques of deformation and transmission electron microscopy (TEM) are described. The impact of TEM on the understanding of deformation in oxides is discussed by relating the observed dislocation substructures to the mechanical properties in several oxide systems. Important information can be obtained on dislocation glide and climb processes in relation to work hardening, recovery, and creep. Yielding and the brittle‐to‐ductile transition temperature are discussed in terms of the magnitude of the Burgers vector in various crystal structures and the influence of dissociation reactions and diffusion. Examples include oxides with close‐packed anions such as MgO, MgAl2O4 BeO, A12O3, TiO2, and Mg2SiO4, and other oxides such as Cu2O, UO2, and SiO2.
Genetic diversity among horse populations with a special focus on the Franches‐Montagnes breed
Authors: Glowatzki‐Mullis M. L. , Muntwyler J. , Pfister W. , Marti E. , Rieder S. , Poncet P. A. , Gaillard C.
Published: October 2005

Genetic characterization helps to assure breed integrity and to assign individuals to defined populations. The objective of this study was to characterize genetic diversity in six horse breeds and to analyse the population structure of the Franches‐Montagnes breed, especially with regard to the degree of introgression with Warmblood. A total of 402 alleles from 50 microsatellite loci were used. The average number of alleles per locus was significantly lower in Thoroughbreds and Arabians. Average heterozygosities between breeds ranged from 0.61 to 0.72. The overall average of the coefficient of gene differentiation because of breed differences was 0.100, with a range of 0.036–0.263. No significant correlation was found between this parameter and the number of alleles per locus. An increase in the number of homozygous loci with increasing inbreeding could not be shown for the Franches‐Montagnes horses. The proportion of shared alleles, combined with the neighbour‐joining method, defined clusters for Icelandic Horse, Comtois, Arabians and Franches‐Montagnes. A more disparate clustering could be seen for European Warmbloods and Thoroughbreds, presumably from frequent grading‐up of Warmbloods with Thoroughbreds. Grading‐up effects were also observed when Bayesian and Monte Carlo resampling approaches were used for individual assignment to a given population. Individual breed assignments to defined reference populations will be very difficult when introgression has occurred. The Bayesian approach within the Franches‐Montagnes breed differentiated individuals with varied proportions of Warmblood.
Predominance of type 1 CD4+T cells in human abdominal aortic aneurysm
Authors: Galle C , Schandené L , Stordeur P , Peignois Y , Ferreira J , Wautrecht J-C , Dereume J-P , Goldman M
Published: October 2005

The functional repertoire of T cells in abdominal aortic aneurysm (AAA) and the exact nature of aortic wall adaptive cellular immune responses still remains a matter of debate. In this study, we sought to determine whether type 1 or type 2 responses occur predominantly in human aneurysmal aortic lesions. We first examined the phenotype and cytokine secretion profile of T lymphocytes freshly isolated from aneurysmal aortic wall for comparison with their circulating counterparts using flow cytometry. We found that both populations of infiltrating CD4+ and CD8+T cells displayed a unique activated memory phenotype. In addition, we identified the presence in human aneurysmal aortic lesion of CD4+T cells producing high levels of interferon (IFN)-γ but not interleukin (IL)-4, reflecting their type 1 nature. Quantitative analysis of cytokine gene expression confirmed increased IFN-γ transcript levels in infiltrating cells compared to controls. We next analysed aortic wall responses using LightCycler-based quantitative real-time reverse transcription-polymerase chain reaction. Compared to control non-diseased aortic samples, we demonstrated that whole AAA tissues exhibited high mRNA levels of IFN-γ but not IL-4. Overexpression of the transcription factor T-bet in the absence of significant GATA-3 expression further assessed the type 1 polarization of aortic wall immune responses. These findings indicate that type 1 CD4+T cells predominate in human AAA lesions. This study has important implications for the pathogenesis of aneurysm disease. Through the production of IFN-γ, T cells may indeed contribute to orchestrate extracellular matrix remodelling.
Long‐term records of strontium isotopic composition in tree rings suggest changes in forest calcium sources in the early 20th century
Authors: Drouet Thomas , Herbauts Jacques , Demaiffe Daniel
Published: October 2005

Many studies made in Europe and North America have shown an increasing depletion of exchangeable base cations that may cause tree nutritional deficiencies in sensitive soils. We use radial variation of strontium isotope in tree‐rings (87Sr/86Sr ratio) to monitor possible changes in Ca sources for tree nutrition (Sr is used as an analog to Ca). The two main sources of Ca in forest stands are mineral weathering release and atmospheric inputs. Measurements in several forest stands in temperate regions show a steep decrease from pith to outer wood of the Sr isotope ratio from∼1870 to∼1920 except for stands developed on soils with a higher Ca status. This suggests a decrease of the weathering contribution (high 87Sr/86Sr ratio) when cations are displaced from the soil exchange complex by acid deposition at a rate faster than the replenishment of the cation pool by mineral weathering. This displacement enhances the atmospheric contribution, which is characterized by a low 87Sr/86Sr ratio. Tree‐ring chronologies are an exceptional historic‐timing record of chemical changes in the soil environment induced by atmospheric pollution. The reliability of the tree‐ring recorder has been verified with a well‐controlled nutritional perturbation in the context of a limed forest stand (with a known liming Sr isotopic signature). Our data suggest that forest ecosystems were affected by atmospheric inputs of strong acids earlier than previously thought.
Vegetation, climatic changes and net carbon sequestration in a North‐Scandinavian subarctic mire over 30 years
Authors: Malmer Nils , Johansson Torbjörn , Olsrud Maria , Christensen Torben R.
Published: October 2005

This study deals with changes in the plant cover and its net carbon sequestration over 30 years on a subarctic Sphagnum‐mire with permafrost near Abisko, northernmost Sweden, in relation to climatic variations during the same period. Aerial colour infrared images from 1970 and 2000 were compared to reveal changes in surface structure and vegetation over the whole mire, while the plant populations were studied within a smaller, mainly ombrotrophic part. The results demonstrated two processes, namely (1) that wet sites dominated by graminoids expanded while hummock sites dominated by dwarf shrubs receded, and (2) that on the hummocks lichens expanded while evergreen dwarf shrubs and mosses decreased, both processes creating an instability in the surface structure. A successive degradation of the permafrost is the likely reason for the increase in wet areas, while the changes in the hummock vegetation might have resulted from higher spring temperatures giving rise to an intensified snow melt, exposing the vegetation to frost drought. Because of the vegetation changes, the annual litter input of carbon to the mire has increased slightly, by 4 g m−2 a−1 (7.3%), over these years while an increased erosion has resulted in a loss of 40–80 Mg carbon or 7–17 g m−2 a−1 for the entire mire over the same period. As the recalcitrant proportion of the litter has decreased, the decay rate in the acrotelm might be expected to increase in the future.
Theory and performance of an infrared heater for ecosystem warming
Authors: Kimball B. A.
Published: October 2005

In order to study the likely effects of global warming on future ecosystems, a method for applying a heating treatment to open‐field plant canopies (i.e. a temperature free‐air controlled enhancement (T‐FACE) system) is needed which will warm vegetation as expected by the future climate. One method which shows promise is infrared heating, but a theory of operation is needed for predicting the performance of infrared heaters. Therefore, a theoretical equation was derived to predict the thermal radiation power required to warm a plant canopy per degree rise in temperature per unit of heated land area. Another equation was derived to predict the thermal radiation efficiency of an incoloy rod infrared heater as a function of wind speed. An actual infrared heater system was also assembled which utilized two infrared thermometers to measure the temperature of a heated plot and that of an adjacent reference plot and which used proportional–integrative–derivative control of the heater to maintain a constant temperature difference between the two plots. Provided that it was not operated too high above the canopy, the heater system was able to maintain a constant set‐point difference very well. Furthermore, there was good agreement between the measured and theoretical unit thermal radiation power requirements when tested on a Sudan grass (Sorghum vulgare) canopy. One problem that has been identified for infrared heating of experimental plots is that the vapor pressure gradients (VPGs) from inside the leaves to the air outside would not be the same as would be expected if the warming were performed by heating the air everywhere (i.e. by global warming). Therefore, a theoretical equation was derived to compute how much water an infrared‐warmed plant would lose in normal air compared with what it would have lost in air which had been warmed at constant relative humidity, as is predicted with global warming. On an hourly or daily basis, it proposed that this amount of water could be added back to plants using a drip irrigation system as a first‐order correction to this VPG problem.
Mollusc community patterns and species response curves along a mineral richness gradient: a case study in fens
Authors: Horsák Michal
Published: October 2005

Aim The goals of this study were to: (1) compare water conductivity and pH as proxy measures of mineral richness in relation to mollusc assemblages in fens, (2) examine the patterns of mollusc species richness along the gradient of mineral richness based on these factors, (3) model species–response curves and analyse calcicole–calcifuge behaviour of molluscs, and (4) compare the results with those from other studies concerning non‐marine mollusc ecology.

Location Altogether, 135 treeless spring fen sites were sampled within the area of the Western Carpathians (east Czech Republic, north‐west Slovakia and south Poland; overall extent of study area was 12,000 km2).

Methods Mollusc communities were recorded quantitatively from a homogeneous area of 16 m2. Water conductivity and pH were measured in the field. The patterns of local species diversity along selected gradients, and species–response curves, were modelled using generalized linear models (GLM) and generalized additive models (GAM), both using the Poisson distribution.

Results When the most acid sites (practically free of molluscs) were excluded, conductivity expressed the sites’ mineral richness and base saturation within the entire gradient, in contrast to pH. In the base‐rich sites, pH did not correlate with mineral richness. A unimodal response of local species diversity to mineral richness (expressed as conductivity) was found. In the extremely mineral‐rich, tufa‐forming sites (conductivity > 600 μS cm−1) a decrease in species diversity was encountered. Response curves of the most common species showed clear differentiation of their niches. Significant models of either unimodal or monotonic form were fitted for 18 of the 30 species analysed. Species showed five types of calcicole–calcifuge behaviour: (1) a decreasing monotonic response curve and a preference for the really acid sites; (2) a skewed unimodal response curve with the optimum shifted towards the slightly acid sites; (3) a symmetrical unimodal model response curve with the optimum in the base‐rich sites, with no or slight tufa precipitation; (4) a skewed unimodal response curve but with the optimum shifted to the more mineral‐rich sites; and (5) an increasingly monotonic response curve, the optimum in the extremely base‐rich sites with strong tufa precipitation.

Main conclusions Conductivity is the only reliable proxy measure of mineral richness across the entire gradient, within the confines of this study. This information is of great ecological significance in studies of fen mollusc communities. Species richness does not increase with increasing mineral richness along the entire gradient: only a few species are able to dwell in the extremely base‐rich sites. The five types of calcicole–calcifuge behaviour seen in species living in fens have a wider application: data published so far suggest they are also applicable to mollusc communities in other habitats.
Reciprocal distribution of two congeneric trees, Betula platyphylla var. japonica and Betula maximowicziana, in a landscape dominated by anthropogenic disturbances in northeastern Japan
Authors: Osumi Katsuhiro
Published: October 2005

Aim  Information has been compiled on disturbance regimes and the life‐history characteristics of Betula platyphylla var. japonica (Miq.) Hara and B. maximowicziana Regel to investigate the impact of humans on the present distribution patterns of these two congeneric tree species.

Location  The study area is in the central region of the northern Kitakami Mountain Range, located in the northeast of Honshu Island, Japan.

Methods  First, the present distributions of B. maximowicziana and B. platyphylla var. japonica were mapped at the landscape scale. To examine the factors affecting the distribution patterns, topographic features and past land use were taken into account. Second, life‐history traits of both species were clarified at various growth stages either by fieldwork or through a literature search. Previous studies have provided some information on seed production, seed dispersal, seedling dynamics, sprouting, and growth. In the present study, field observations and experiments were conducted regarding seed‐bank formation, size and age at reproduction, and the life span of canopy trees.

Results  Betula platyphylla var. japonica and B. maximowicziana were spatially segregated in the studied landscape (14,000 ha). The distribution of each species was correlated more strongly with land use at the beginning of the twentieth century than with site environmental factors such as altitude or slope angle. Betula platyphylla var. japonica was distributed more frequently on former grasslands, whereas B. maximowicziana was almost exclusively limited to past old‐growth forests. As typical pioneers, the two species showed similar life‐history traits but differed in several critical points. Betula platyphylla var. japonica has a vigorous sprouting ability, which might increase its resistance to burning and logging, whereas B. maximowicziana forms a persistent seed bank in the soil, indicating an advantage in regenerating in disturbances found in forest communities. Other critical differences were detected in age‐related characteristics such as minimum age of reproduction and life span.

Main conclusions  The earlier reproductive maturity and the shorter life span of B. platyphylla var. japonica indicate a shorter population cycle than that for B. maximowicziana. The latter would be excluded from grasslands that were burned frequently, as a result of the longer time span before initial reproduction and its poor sprouting ability. In contrast, B. platyphylla var. japonica would be excluded from old‐growth forests, where disturbance was infrequent, owing to its shorter life span and lack of a persistent seed bank.
Self‐reported anti‐social behaviour: prevalence and risk factors amongst adolescents with and without intellectual disability
Authors: Dickson K. , Emerson E. , Hatton C.
Published: October 2005

Background  Research has suggested increased risk of anti‐social behaviour amongst individuals with intellectual disability (ID).

Methods  This study reports the results of a secondary analysis of data relating to self‐reported anti‐social behaviour, obtained from the 1999 Office for National Statistics (ONS) study of the mental health of children and adolescents in Great Britain. Self‐report data from 4174 adolescents was available. Within this group, a sub‐group of 98 adolescents with ID was identified. Data covered a variety of sub‐types of anti‐social behaviour.

Results  Comparisons of individuals with ID and those without ID indicated a significantly higher prevalence of a number of types of self‐reported anti‐social behaviour in the ID sample. Further analyses indicated however, that these between group differences were accounted for by the higher rates of social deprivation and child mental health problems among the ID sample.

Conclusions  Rather than ID per se being associated with increased rates of anti‐social behaviour, adolescents with ID may be more likely to experience risk factors (lower socio‐economic status and mental health problems) known to be associated with anti‐social behaviour. The clinical implications of this and possible future directions for research are discussed.
Further examination of relationships between life events and psychiatric symptoms in adults with intellectual disability
Authors: Hamilton D. , Sutherland G. , Iacono T.
Published: October 2005

Background  It has been proposed that people with intellectual disability (ID) might be similar to the general population in the way they respond to significant life events. Some preliminary findings have demonstrated that adults with ID who have experienced recent life events have an increased probability of having psychiatric problems. The aims of the present study were to determine whether previous findings can be replicated, and to examine the influence of additional diagnoses associated with ID on the strength of relationships between life event frequency and psychiatric problems.

Methods  Adults with ID (n = 624), living either in staffed community accommodation or in family or foster homes, were assessed on the Developmental Behaviour Checklist for Adults (DBC‐A) and a 37‐item life events checklist. Carers who knew the person well acted as proxy informants.

Results  People living in staffed accommodation experienced more life events than people living with natural or foster families. Life event frequency predicted DBC‐A total score, five of six sub‐scale scores, and caseness status, after significant demographic factors were taken into account. However, the strength of correlations between life event frequency and DBC‐A total score varied among sub‐groups identified by type of developmental disability and level of ID.

Conclusions  Weak but significant associations between emotional and behavioural problems and life events experienced by adults with ID were demonstrated, but it was also shown that the strength of such associations varies among sub‐groups of this heterogeneous population. Future research needs to take account of the circumstances surrounding the life changes, the period of time over which changes might have taken place, and the meaning that the person might attach to the changes. Research into the causal relationship between exposure to life events and the onset of psychiatric problems is also warranted.
Effects of short‐term hypoxia on neuroglobin levels and localization in mouse brain tissues
Authors: Hundahl C. , Stoltenberg M. , Fago A. , Weber R. E. , Dewilde S. , Fordel E. , Danscher G.
Published: October 2005

Nerve cells are highly susceptible to ischemic and hypoxic injuries. The neuroglobin (Ngb), found in vertebrate nerve cells, has been suggested to protect nerve cells from ischemic episodes by a yet unknown mechanism. However, contradicting reports exist regarding localization and up‐regulation of Ngb in response to hypoxia. The aim of the present study was to probe the distribution of Ngb proteins in mouse brain and retina by immunohistochemistry, and to quantify the levels of Ngb mRNA by reverse‐transcription‐polymerase chain reaction (RT‐PCR) after short‐term (2 h) exposure to 7.6% oxygen. We found Ngb to be present throughout the neocortex, most abundantly in the perirhinal, entorhinal and temporal cortical areas, the thalamus and hypothalamus, the choroid plexus, the olfactory bulb and the cranial nerve nuclei in the brainstem. Intense staining was observed in the mesencephalic central grey area and the Purkinje cells. Two‐hour hypoxic exposure caused no detectable changes in staining intensity or spatial distribution of Ngb neither in the Purkinje cells nor in any other brain areas observed. The RT‐PCR data supported the lack of differences in brain Ngb levels between normal and oxygen‐deprived animals. In the retina, Ngb localization by immunohistochemistry was confined to the inner segments of the photoreceptors, the plexiform layers and the ganglion cells. Short‐termed hypoxia did not change retinal Ngb levels as assessed by both techniques. The lack of Ngb up‐regulation in the brain is consistent with results from previous long‐term hypoxic experiments, suggesting that Ngb is not regulated by pure hypoxia in vivo.
Subarachnoid injection of Microfil reveals connections between cerebrospinal fluid and nasal lymphatics in the non‐human primate
Authors: Johnston M. , Zakharov A. , Koh L. , Armstrong D.
Published: October 2005

Based on quantitative and qualitative studies in a variety of mammalian species, it would appear that a significant portion of cerebrospinal fluid (CSF) drainage is associated with transport along cranial and spinal nerves with absorption taking place into lymphatic vessels external to the central nervous system. CSF appears to convect primarily through the cribriform plate into lymphatics associated with the submucosa of the olfactory and respiratory epithelium. However, the significance of this pathway for CSF absorption in primates has never been established unequivocally. In past studies, we infused Microfil into the subarachnoid compartment of numerous species to visualize CSF transport pathways. The success of this method encouraged us to use a similar approach in the non‐human primate. Yellow Microfil® was injected post mortem into the cisterna magna of 6 years old Barbados green monkeys (Cercopithecus aethiops sabeus, n = 6). Macroscopic and microscopic examination revealed that Microfil was (1) distributed throughout the subarachnoid compartment, (2) located in the perineurial spaces associated with the fila olfactoria, (3) present within the olfactory submucosa, and (4) situated within an extensive network of lymphatic vessels in the nasal submucosa, nasal septum and turbinate tissues. We conclude that the Microfil distribution patterns in the monkey were very similar to those observed in many other species suggesting that significant nasal lymphatic uptake of CSF occurs in the non‐human primate.
Co‐expression/co‐location of S100 proteins (S100B, S100A1 and S100A2) and protein kinase C (PKC‐β, ‐η and ‐ζ) in a rat model of cerebral basilar artery vasospasm
Authors: Lefranc F. , Decaestecker C. , Brotchi J. , Heizmann C. W. , Dewitte O. , Kiss R. , Mijatovic T.
Published: October 2005

Object: The cellular events leading to cerebral vasospasm after subarachnoid haemorrhages (SAH) involve a number of members of the protein kinase C (PKC) family. However, whereas calcium is thought to play a number of major roles in the pathophysiology of SAH, a number of PKCs function independently of calcium. We recently emphasized the potential role of the calcium‐binding S100 proteins in a ‘double haemorrhage’ rat model of SAH‐induced vasospasm. A number of S100 proteins are known to interfere directly with PKC, or indirectly with PKC substrates. We therefore investigated whether specific S100 proteins and PKCs are co‐expressed/co‐located in a rat model of SAH‐induced vasospasm. Methods and Results: SAH‐induced vasospasm in rats (by means of a double cisternal injection of autologous blood from a rat femoral artery) distinctly modified the expression levels of calcium‐dependent PKC‐α and PKC‐β and calcium‐independent PKC‐η and PKC‐ζ in endothelial and smooth‐muscle cells. The RNA levels of these four PKC isotypes were determined by quantitative RT‐PCR. The present study reveals that, in endothelial cells, the S100B expression/location correlate well with those of PKC‐η, and those of S100A1 with PKC‐β. In smooth‐muscle cells S100A2 expression/location correlate with those of PKC‐η, and those of S100B with PKC‐ζ. Conclusion: The present data argue in favour of a joint action of the S100 protein network and the PKC signalling pathway during cerebral vasospasm.