bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen cycling in grazed pastures at elevated CO2: N returns by ruminants
Authors: Allard Vincent , Newton Paul C. D. , Lieffering Mark , Clark Harry , Matthew Cory , Soussana Jean‐François , Gray Yvonne S.
Published: December 2004

In pastures grazed by large herbivores, nutrients cycle both through litter and animal excreta. We compared nitrogen (N) returns from sheep grazing a temperate pasture exposed to ambient or elevated CO2 (475 μmol mol−1) in a FACE (Free Air CO2 Enrichment) experiment established in the spring of 1997. In the spring of 2000 and 2001, we measured the chemical composition of the diet, sheep faeces and of individual plant species before grazing to characterize feed intake and to compare the intake of N to the N produced in faeces. In both years under elevated CO2, leaves of the individual species exhibited lower N concentrations and higher water‐soluble carbohydrate (WSC) concentrations. There was a significantly greater proportion of legume in the diet at elevated CO2 but, together with the changes in chemical composition of individual species, this resulted in diets that had similar N but higher WSC and digestibility for both ambient and elevated CO2. We found that a greater proportion of dietary N was partitioned to urine at elevated CO2, probably because of the higher proportion of legume N in the diet, with possible differences in protein quality. A potentially significant consequence of this change in partitioning is greater N loss through volatilization at higher CO2 levels.
Phenological responses in maple to experimental atmospheric warming and CO2enrichment
Authors: Norby Richard J. , Hartz‐Rubin Jennifer S. , Verbrugge Maria J.
Published: December 2004

Evidence that global warming has altered the phenology of the biosphere, possibly contributing to increased plant production in the northern hemisphere, has come from a diversity of observations at scales ranging from the view of the back yard to satellite images of the earth. These observations, coupled with an understanding of the effects of temperature on plant phenology, suggest that future changes in the atmosphere and climate could alter plant phenology with unknown or unpredictable consequences. We assessed the effects of simulated climatic warming and atmospheric CO2enrichment on the spring and autumn phenology of maple trees (Acer rubrumandA. saccharum) growing for four years in open‐top field chambers. CO2enrichment (+300 ppm) had no consistent effects on the timing of budbreak and leaf unfolding in the spring or leaf abscission in the autumn. Warming (+4°C) usually had predictable effects: in two of the three years of assessment, budbreak occurred earlier in warm chambers than in ambient temperature chambers, and leaf abscission always occurred later. The lengthening of the growing season could contribute to increased productivity, although effects of temperature on other physiological processes can concurrently have negative effects on productivity. In 1995, budbreak was unexpectedly delayed in the warmer chambers, apparently the result of advanced budbreak leading to injury from a late‐spring frost. Likewise, there was increased risk associated with longer leaf retention in the autumn: in 1994, leaves in the warm chambers were killed by freezing temperatures before they had senesced. These observations support the premise that global warming could increase the length of the growing season. Phenological responses should, therefore, be part of any assessment of the possible consequences of global change, but our results also suggest that those responses may not always have positive effects on production.
Role of lakes for organic carbon cycling in the boreal zone
Authors: Algesten Grete , Sobek Sebastian , Bergström Ann‐Kristin , Ågren Anneli , Tranvik Lars J. , Jansson Mats
Published: December 2004

We calculated the carbon loss (mineralization plus sedimentation) and net CO2 escape to the atmosphere for 79 536 lakes and total running water in 21 major Scandinavian catchments (size range 437–48 263 km2). Between 30% and 80% of the total organic carbon that entered the freshwater ecosystems was lost in lakes. Mineralization in lakes and subsequent CO2 emission to the atmosphere was by far the most important carbon loss process. The withdrawal capacity of lakes on the catchment scale was closely correlated to the mean residence time of surface water in the catchment, and to some extent to the annual mean temperature represented by latitude. This result implies that variation of the hydrology can be a more important determinant of CO2 emission from lakes than temperature fluctuations. Mineralization of terrestrially derived organic carbon in lakes is an important regulator of organic carbon export to the sea and may affect the net exchange of CO2 between the atmosphere and the boreal landscape.
Experimental evidence of reduced diversity of seedlings due to climate modification in a Mediterranean‐type community
Authors: Lloret Francisco , Peñuelas Josep , Estiarte Marc
Published: December 2004

We are still lacking in experimental evidence of the effects of climate change on the richness of plant species under field conditions. We report a decrease in the species richness of recruited seedlings in a Mediterranean shrubland in experimentally induced drought and warming over 4 consecutive years. Drought decreased the number of emerging seedlings and their respective species richness. Warming also decreased seedling species richness, but it did not affect the number of emerging seedlings. Species that produce fewer recruits are more likely to disappear in drier or warmer scenarios. However, when the effect of induced climate treatment was greatest, the more abundant species in control stands were not necessarily the ones least affected by treatment; in other words, species‐idiosyncratic responses may occur. These results show that demographic processes are sensitive to minor climate changes, with probable consequences on the diversity and structure of the future plant communities.
Vegetation structure characteristics and relationships of Kalahari woodlands and savannas
Authors: Privette J.L. , Tian Y. , Roberts G. , Scholes R.J. , Wang Y. , Caylor K.K. , Frost P. , Mukelabai M.
Published: December 2004

The Kalahari Transect is one of several International Geosphere–Biosphere Programme (IGBP) transects designed to address global change questions at the regional scale, in particular by exploiting natural parameter gradients (Koch et al., 1995). In March 2000, we collected near‐synoptic vegetation structural data at five sites spanning the Kalahari's large precipitation gradient (about 300–1000 mm yr−1) from southern Botswana (∼24°S) to Zambia (∼15°S). All sites were within the expansive Kalahari sandsheet. Common parameters, including plant area index (PAI), leaf area index (LAI) and canopy cover (CC), were measured or derived using several indirect instruments and at multiple spatial scales. Results show that CC and PAI increase with increasing mean annual precipitation. Canopy clumping, defined by the deviation of the gap size distribution from that of randomly distributed foliage, was fairly constant along the gradient. We provide empirical relationships relating these parameters to each other and to precipitation. These results, combined with those in companion Kalahari Transect studies, provide a unique and coherent test bed for ecological modeling. The data may be used to parameterize process models, as well as test internally predicted parameters and their variability in response to well‐characterized climatological differences.
Response of different decomposer communities to the manipulation of moisture availability: potential effects of changing precipitation patterns
Authors: Taylor Astrid Rita , Schröter Dagmar , Pflug Anne , Wolters Volkmar
Published: December 2004

The potential impacts of changes in precipitation patterns associated with global climate change on the relationship between soil community diversity and litter decomposition were investigated. For a period of ca. 5 months, two decomposer communities in litterbags (1000 and 45 μm mesh size) containing spruce litter were subjected to two irrigation treatments: constant and fluctuating (drying/rewetting) moisture conditions. The latter were expected to induce moisture stress on the decomposer communities. The two mesh sizes were used to exclude different faunal components from the decomposer communities. The 1000 μm mesh excluded only the macrofauna, whereas the 45 μm mesh excluded both the macro‐ and mesofauna. In the short‐term perspective of the present study, mesofauna abundance showed no response to imposed fluctuating moisture conditions. Irrespective of the presence of mesofauna, mass loss, microbial biomass and the control mechanisms, regulating carbon mineralization appeared unaffected by fluctuating moisture conditions. The reduction in the functional/structural diversity of the decomposer communities in the 45 μm litterbags resulted in strongly increased Nematoda abundance but it did not alter the response of Nematoda to fluctuating moisture conditions. Processes in the nitrogen (N)‐cycle and mass loss were sensitive indicators of changes in the structural and functional complexity of decomposer communities. However, a negative effect of fluctuating moisture conditions on extractable N was coupled to the presence of mesofauna. Extremes in rainfall patterns, generated by climate change, may have a negative impact on the availability of nutrients, particularly N, for plants. This effect could be amplified by an additional impoverishment in the structural and functional complexity of the respective decomposer communities.
Role of land cover changes for atmospheric CO2 increase and climate change during the last 150 years
Authors: Brovkin Victor , Sitch Stephen , Von Bloh Werner , Claussen Martin , Bauer Eva , Cramer Wolfgang
Published: December 2004

We assess the role of changing natural (volcanic, aerosol, insolation) and anthropogenic (CO2 emissions, land cover) forcings on the global climate system over the last 150 years using an earth system model of intermediate complexity, CLIMBER‐2. We apply several datasets of historical land‐use reconstructions: the cropland dataset by Ramankutty & Foley (1999) (R&F), the HYDE land cover dataset of Klein Goldewijk (2001), and the land‐use emissions data from Houghton & Hackler (2002). Comparison between the simulated and observed temporal evolution of atmospheric CO2 and δ13CO2 are used to evaluate these datasets. To check model uncertainty, CLIMBER‐2 was coupled to the more complex Lund–Potsdam–Jena (LPJ) dynamic global vegetation model.

In simulation with R&F dataset, biogeophysical mechanisms due to land cover changes tend to decrease global air temperature by 0.26°C, while biogeochemical mechanisms act to warm the climate by 0.18°C. The net effect on climate is negligible on a global scale, but pronounced over the land in the temperate and high northern latitudes where a cooling due to an increase in land surface albedo offsets the warming due to land‐use CO2 emissions.

Land cover changes led to estimated increases in atmospheric CO2 of between 22 and 43 ppmv. Over the entire period 1800–2000, simulated δ13CO2 with HYDE compares most favourably with ice core during 1850–1950 and Cape Grim data, indicating preference of earlier land clearance in HYDE over R&F. In relative terms, land cover forcing corresponds to 25–49% of the observed growth in atmospheric CO2. This contribution declined from 36–60% during 1850–1960 to 4–35% during 1960–2000. CLIMBER‐2‐LPJ simulates the land cover contribution to atmospheric CO2 growth to decrease from 68% during 1900–1960 to 12% in the 1980s. Overall, our simulations show a decline in the relative role of land cover changes for atmospheric CO2 increase during the last 150 years.
Nitrogen input mediates the effect of free‐air CO2 enrichment on mycorrhizal fungal abundance
Authors: Staddon Philip L. , Jakobsen Iver , Blum Herbert
Published: December 2004

Plots containing Lolium perenne L., Trifolium repens L. or a mixture of both plant species were exposed to elevated atmospheric CO2 (eCO2) for 10 consecutive seasons using free‐air CO2 enrichment technology at ETH Zürich, Switzerland. The CO2 treatment was crossed with a two‐level nitrogen (N) fertilization treatment. In the tenth year, soil samples were collected on three occasions through the growing season to assess the impact of eCO2 and N fertilization on mycorrhizal fungal abundance. Soil moisture content, which varied with harvest date, was linked to the vegetation type and was higher under eCO2. Root weight density was affected by vegetation type: lower for clover, higher for grass. Root weight density was stimulated by eCO2 and decreased by high N fertilization. The percent root length colonized by mycorrhizal fungi was lowest in the clover plots and highest in the grass plots. High N significantly decreased root length colonized. There was no overall effect of eCO2 on root length colonized; however, there was a significant eCO2× N interaction: eCO2 increased root length colonized at high N, but decreased root length colonized at low N. Extraradical mycorrhizal hyphal density was linked to soil moisture content. Extraradical mycorrhizal hyphal density was not affected by eCO2 or high N individually, but as for root length colonized, there was a significant eCO2× N interaction: eCO2 increased extraradical mycorrhizal hyphal density at low N but not at high N. These environmental effects on root colonization and external mycorrhizal hyphae were independent of soil moisture content and root weight density. This field study demonstrated a significant mediating effect of N fertilization on the response of arbuscular mycorrhizal fungi to eCO2 irrespective of any change in root biomass.
Effects of climate on the growth of exotic and indigenous trees in central Zambia
Authors: Chidumayo E. N.
Published: December 2004

Aim Climate change has far‐reaching effects on species and ecosystems. The aims of this study were to determine how climate factors affect the growth pattern of indigenous and exotic trees in Zambia and to predict tree growth responses to a warmer climate with the use of mathematical models.

Location Two savanna sites in central Zambia.

Methods Diameter at breast height (1.3 m above ground, d.b.h.) of 91 permanently marked trees belonging to three indigenous and four exotic species was measured fortnightly for periods of 1–2 years from 1998 to 2003. Correlation and regression analysis was used to determine the effect of climate factors (minimum, maximum and average temperature and rainfall) on monthly daily d.b.h. increment of each species. Regression models were used to predict the growth behaviour of trees under a 0.5 °C warmer climate.

Results Interactions between temperature and rainfall explained 60–98% of the variation in d.b.h. increment in all the tree species, except the exoticEucalyptus grandis. For deciduous species, stem expansion was delayed by 2–12 weeks following leaf‐flush and d.b.h. increment peaked during the rainy season. Evergreen and deciduous species could not be separated on the basis of annual d.b.h. increment because the higher growth rates of deciduous species compensated for the shorter growing period. Mathematical models predicted slight changes in d.b.h. growth pattern under a 0.5 °C warmer climate in five of the seven species. Significant changes in d.b.h. growth patterns were predicted in the indigenousBridelia micranthaand exoticGmelina arboreaunder a warmer climate. However, models failed to adequately represent potential soil water stress that might result from changes in tree growth patterns and a warmer climate.

Main conclusions Climate factors explained a large proportion of the variation in diameter growth of both indigenous and exotic trees, rendering it possible to model tree growth patterns from climate data. Tree growth models suggest that a rise in temperature of 0.5 °C is unlikely to induce significant changes in the growth behaviour of the majority of the studied species. However, because the growth behaviour of some species may be substantially affected by climate change, it is recommended that strategies for the future production of such climate‐sensitive trees should incorporate aspects of climate change.
The biogeography of Hoffmannseggia (Leguminosae, Caesalpinioideae, Caesalpinieae): a tale of many travels
Authors: Simpson Beryl B. , Tate Jennifer A. , Weeks Andrea
Published: December 2004

Aim  The flowering plant genus Hoffmannseggia consists of 21 species distributed amphitropically between the arid regions of the south‐western United States and adjacent Mexico, and west‐central South America. This pattern of geographical disjunction is shared by numerous other angiosperm genera and has been the subject of discussions for more than a century with various authors advocating a northern origin for particular taxa and others advocating a southern origin. This study uses a well‐supported phylogeny of a genus with numerous species in each area to address the issues of a northern or southern origin and the facility with which organisms move between the two continents.

Location  South‐western United States and northern Mexico, northern Chile and Argentina, southern Bolivia, and western Peru.

Methods  Using DNA sequence data from the nuclear and chloroplast genomes, we generated a phylogenetic hypothesis for all species of Hoffmannseggia rooted with Zuccagnia and Balsamocarpon. Geographical data were optimized on the resultant tree to assess the probable continent of origin for the genus, the pattern of disjunctions between North and South America, and species radiations within the genus.

Main conclusions  Hoffmannseggia arose in South America and initially split into a suffrutescent (somewhat woody) and an herbaceous clade. Within each of these major clades, there have been at least two exchanges between North and South America. There are no data to support an ancestral pan‐American range for Hoffmannseggia and we therefore ascribe the amphitropical disjunctions to long‐distance dispersal. The phylogeny clearly shows that all dispersals were from South to North America and they occurred at different times and thus the pattern is not the result of a single simultaneous set of dispersals.
Hair removal using an 800‐nm Diode Laser: Comparison at different treatment intervals of 45, 60, and 90 days
Authors: Bouzari Navid , Tabatabai Hossein , Abbasi Zahra , Firooz Alireza , Dowlati Yahya
Published: December 2004

Background  Some laser irradiation parameters such as wavelength, fluence, pulse duration, and spot size have been shown to influence the damage of any target inside the skin, however, the role of some patients’ factors such as hair growth cycle is still under debate.

Objective  To determine the association of treatment interval and laser treatment outcome.

Methods  In a retrospective chart review of 176 patients undergoing laser‐assisted hair removal with a diode laser 24 patients were selected. All accepted to cease the therapy, and be followed‐up for 5 months. At the end of the study the patients were questioned about the efficacy of the treatment as well as the adverse effects. Hair counting was also performed. The adverse effects (pain, blister or erosion, hyperpigmentation, hypopigmentation, and folliculitis) were questioned during the follow‐up period.

Results  The mean hair reduction was 78.1%, 45.8%, and 28.7% in 45, 60, and 90‐day interval groups, respectively (P < 0.0001).

Conclusion  The treatment interval was related to the treatment outcome in our study.
Skin diseases in south‐east Nigeria: A current perspective
Authors: Nnoruka E. N.
Published: December 2004

Background and objective  The incidence of skin diseases in south‐east Nigeria during the present decade was analyzed and compared with results from other parts of Nigeria, particularly those in the same zone, obtained more than 30 years ago. This study was carried out to update the recent clinical picture of skin diseases in our environment in view of the rapid development, urbanization and advances in the region.

Patients and methods  Consecutive new patients seen at the dermatology clinic of the University of Nigeria, Teaching Hospital, Enugu, Nigeria, from February 1999 to March 2001 were included in this prospective study. Only cases seen and examined by the author were included in this study to ensure uniformity of diagnosis.

Results  A total of 2871 patients were observed within the study period. Adults accounted for 69.7% and were aged between 18 and 73 years, while the male : female ratio was 1.3 : 1. Allergic skin diseases (24.9%) were the commonest skin disorders identified, as opposed to infestations which accounted for an extremely high result of 33.7% (for the same region between 1968 and 1971). In second place was infections/infestations (19.1%). A reversal of picture was thus observed. Within the allergic disorders; eczemas/dermatitis were found to be the most prevalent followed by follicular (13.7%) and pigmentary disorders (11.1%). Sexually transmitted diseases and HIV/AIDs have increased significantly and accounted for 5.4%. Blistering diseases (1.1%) and malignancies (0.5%) occurred less frequently, similar to results found in resent decades for the same region.

Conclusion  The current picture of skin diseases in south‐east Nigeria has changed significantly from mere infections to allergic skin, follicular and pigmentary disorders. Cutaneous lesions secondary to STDs and HIV/AIDs have also increased. Skin lesions related to malnutrition, kwashiorkor and starvation were not observed nor were cutaneous tuberculosis, yaws or pediculosis, while blistering disorders and malignancies remained almost the same. The current picture is similar to that in other developing and Afro‐Caribbean countries. Primary‐care physicians and health‐care providers in Nigeria/Africa need to be aware of the globally changing pattern of skin diseases in the region to enable the allocation of necessary resources (financial, material and human) to manage these skin diseases.
Diatom biostratigraphy of the Cenozoic glaciomarine Pagodroma Group, northern Prince Charles Mountains, East Antarctica*
Authors: WHITEHEAD J. M. , HARWOOD D. M. , McKELVEY B. C. , HAMBREY M. J. , McMINN A.
Published: December 2004

In the northern Prince Charles Mountains glaciomarine sediments of the Pagodroma Group outcrop on Fisher Massif (Mt Johnston and Fisher Bench Formations) and at the Amery Oasis (Battye Glacier and Bardin Bluffs Formations), at locations 300 and 250 km south of the Amery Ice Shelf edge, respectively. Most of the Pagodroma Group consists of ice‐proximal glaciomarine diamict, and a much subordinate (<2%) amount of more ice‐distal mudstone. Microfossil biostratigraphy based upon in situ and glacially reworked diatoms constrains the ages of the four formations, and identifies at least six intervals of marine fjordal deposition. Sparse diatoms in Mt Johnston Formation diamicts indicate an Early Oligocene age. However, it is unclear whether these diatoms are in situ or else are glacially reworked and represent either an immediately prior or more remote past interglacial. The Battye Glacier and Fisher Bench Formations contain in situ diatoms and are broadly time equivalent, the former dating between 10.7 and 9.0 Ma and the latter between 12.1 or 10.7 Ma and 8.5 Ma. In situ diatoms indicate the Bardin Bluffs Formation to have been deposited between 2.6 and either 1.8 or 0.99 Ma. Glacially reworked diatoms in the Bardin Bluffs and Fisher Bench Formations identify four depositional intervals. The reworked taxa are sourced from Eocene–Oligocene (>30.1 Ma), Middle Miocene (14.5–12.5 Ma and 12.1–11.5 Ma), Early Pliocene (4.9–3.6 Ma) and, tentatively, Late Pliocene (3.4–2.6 Ma) strata. These microfossil data further develop the interpretation that the Pagodroma Group formed during episodes of reduced glacial extent when, in the absence of an ice shelf, marine waters penetrated far southwards into the Lambert Graben of East Antarctica.
Depositional environment and taphonomy of the ‘strings of beads’: Mesoproterozoic multicellular fossils in the Bangemall Supergroup, Western Australia
Authors: MARTIN D. McB.
Published: December 2004

Enigmatic Mesoproterozoic bedding‐plane structures, informally known as ‘strings of beads’, are common in the Bangemall Supergroup in Western Australia and the Belt Supergroup in North America. The Belt Supergroup structures are formally known as Horodyskia moniliformis, and age constraints show that they are more than 350 million years older than similar 1070 Ma structures in the Bangemall Supergroup. Strings of beads in the Bangemall Supergroup have previously been interpreted as fossils of multicellular organisms based on their morphology and on statistical comparisons with a range of organic and inorganic structures. However, details of their depositional environment and taphonomy, which can provide important insights into their origin, are poorly known. This study shows that strings of beads in the Backdoor Formation of the Bangemall Supergroup were deposited in a subtidal marine‐shelf environment in association with microbial mats and enigmatic dimple marks. The structures are preserved at the base of fine sandstone beds within shoaling‐upward shelfal mudstone and sandstone packages deposited below storm wave‐base. Following deposition from suspension, the strings of beads were bound to the sea floor by microbial mats and their associated mucilage, preventing realignment by palaeocurrents. Relationships between the strings of beads and dimple marks in offshore sandstones suggest that the latter may represent holdfasts to which the strings were originally attached.
Standardized routine outcome measurement: Pot holes in the road to recovery
Authors: Lakeman Richard
Published: December 2004

Abstract:  Routine ‘outcome measurement’ is currently being introduced across Australian mental health services. This paper asserts that routine standardized outcome measurement in its current form can only provide a crude and narrow lens through which to witness recovery. It has only a limited capacity to capture the richness of people's recovery journeys or provide information that can usefully inform care. Indeed, in its implementation nurses may be required to collude in practices or account for practice in ways which run counter to the personal recovery paradigm. Nurses should view a focus on outcomes as an opportunity for critical reflection as well as to seek ways to account for recovery stories in meaningful ways.
Relaxation training methods for nurse managers in Hong Kong: a controlled study
Authors: Yung Paul M. B. , Fung Man Yi , Chan Tony M. F. , Lau Bernard W. K.
Published: December 2004

ABSTRACT:  Nurse managers are under increased stress because of excessive workloads and hospitals’ restructuring which is affecting their work tasks. High levels of stress could affect their mental health. Yet, few stress management training programmes are provided for this population. The purpose of this study was to apply stretch‐release relaxation and cognitive relaxation training to enhance the mental health for nurse managers. A total of 65 nurse managers in Hong Kong were randomly assigned to stretch‐release relaxation (n = 17), cognitive relaxation (n = 18), and a test control group (n = 35). Mental health status was assessed using the Chinese version of State‐Trait Anxiety Inventory and the Chinese version of the General Health Questionnaire. Participants were assessed at the pretreatment session, the fourth posttreatment session, and at the 1‐month follow‐up session. The results revealed both the stretch‐release and cognitive relaxation training enhanced mental health in nurse managers in Hong Kong. The application of relaxation training in enhancing mental health status for nurses and health professionals is discussed.
A fatigue and creep study in austenitic stainless steel 316L used in exhaust pipes of naval gas turbines
Authors: MARTINS R. F. , BRANCO C. M.
Published: December 2004

Exhaust pipes of naval gas turbines are made of thin wall tubing of stainless steel grade AISI 316L. The tubes are fabricated by butt welding of different sections with longitudinal and circumferential joints. The plate thickness is about 4.0 mm, and the working temperature varies between 600 °C and 400 °C in the critical zones of the pipe, in the lower and central areas, respectively. The loadings in the tube induce high‐temperature fatigue and creep‐fatigue cracks have nucleated and propagated in the tube near some welded joints. The paper presents FCGR data obtained in CT specimens of used material taken from the pipes and tested at RT, 335, 500 and 600 °C. Preliminary creep data obtained in tension, in thin‐sheet specimens (about 4 mm thickness), also taken from the conduct wall and tested at 500, 550 and 600 °C are also given. These results are crucial to perform a fatigue‐creep interaction life assessment of the critical parts of the structure in the near future. Finally, the paper presents results of research work to investigate carbide precipitation and formation in virgin thin‐sheet specimens subjected to several types of thermal exposures. In some cases, 3–4 d was the time interval between exposures. Grain size measurements were carried out together with microstructural observations in the SEM. The influence of time, temperature and time interval between thermal exposures was assessed comparing the microstructures.
Model complexity versus scatter in fatigue
Authors: SVENSSON T.
Published: December 2004

Fatigue assessment in industry is often based on simple empirical models, such as the Wöhler curve or the Paris' law. In contrast, fatigue research to a great extent works with very complex models, far from the engineering practice. One explanation for this discrepancy is that the scatter in service fatigue obscures many of the subtle phenomena that can be studied in a laboratory. Here we use a statistical theory for stepwise regression to investigate the role of scatter in the choice of model complexity in fatigue. The results suggest that the amount of complexity used in different design concepts reflects the appreciated knowledge about input parameters. The analysis also points out that even qualitative knowledge about the neglected complexity may be important in order to avoid systematic errors.
Cichlid biogeography: comment and review
Authors: Chakrabarty Prosanta
Published: December 2004

Phylogenetic analyses dealing with disjunct distributions (distributions that require marine dispersal or vicariant events) are reviewed for the Cichlidae. The most corroborated relationship between clades across a Gondwanan disjunction is the sister relationship between Indian and Malagasy cichlids. The minimum age of the Cichlidae as implied by the fossil record is at odds with the timing of the Cretaceous break of the Indian–Madagascar landmass. All well sampled phylogenies for this group fit a pattern reflecting Gondwanan break‐up. Grounds for strictly dispersalist hypotheses are not well founded for any cichlid disjunct distribution, leaving vicariance alternatives as the only explanation.
Twelve‐ and 18‐month‐olds copy actions in terms of goals
Authors: Carpenter Malinda , Call Josep , Tomasello Michael
Published: December 2004

In the context of an imitation game, 12‐ and 18‐month‐old infants saw an adult do such things as make a toy mouse hop across a mat (with sound effects). In one condition (House), the adult ended by placing the mouse in a toy house, whereas in another condition (No House) there was no house present at the final location. Infants at both ages usually simply put the mouse in the house (ignoring the hopping motion and sound effects) in the House condition, presumably because they interpreted the adult's action in terms of this final goal and so ignored the behavioral means. In contrast, infants copied the adult's action (both the hopping motion and the sound effects) when no house was present, presumably because here infants saw the action itself as the adult's only goal. From very early, infants’ social learning is flexible: infants focus on and copy either the end or the means of an adult action as required by the context.
Neurocognitive correlates of socioeconomic status in kindergarten children
Authors: Noble Kimberly G. , Norman M. Frank , Farah Martha J.
Published: December 2004

Socioeconomic status (SES) is strongly associated with cognitive ability and achievement during childhood and beyond. Little is known about the developmental relationships between SES and specific brain systems or their associated cognitive functions. In this study we assessed neurocognitive functioning of kindergarteners from different socioeconomic backgrounds, using tasks drawn from the cognitive neuroscience literature in order to determine how childhood SES predicts the normal variance in performance across different neurocognitive systems. Five neurocognitive systems were examined: the occipitotemporal/visual cognition system, the parietal/spatial cognition system, the medial temporal/memory system, the left perisylvian/language system, and the prefrontal/executive system. SES was disproportionately associated with the last two, with low SES children performing worse than middle SES children on most measures of these systems. Relations among language, executive function, SES and specific aspects of early childhood experience were explored, revealing intercorrelations and a seemingly predominant role of individual differences in language ability involved in SES associations with executive function.
Nightly home hemodialysis: Five and one‐half years of experience in Lynchburg, Virginia
Authors: Lockridge Robert S. , Spencer Maureen , Craft Viola , Pipkin Mary , Campbell Dolores , McPhatter Lesley , Albert Jeanette , Anderson Helen , Jennings Floyd , Barger Terry
Published: December 2004

Background: Lynchburg Nephrology Dialysis Incorporated initiated a nightly home hemodialysis (NHHD) program in September 1997. As of April 30, 2003, 40 patients had completed training; 28 patients were at home and 2 patients were in training. The average age of the patients at the initiation of the home‐based therapy was 50 years, with a range of 23 to 81 years. There have been 24,239 treatments at home with a total of 84.86 patient‐years on NHHD, the longest patient for 66.7 months and the shortest for 1 month.

Methods: Patients dialyzed using the Fresenius 2008H machine, 6 to 10 hr, 5 to 6 nights per week. Treatment parameters included a blood flow rate of 200 to 250 mL/min; a dialysis flow rate of 200 to 300 mL/min; and a standard dialysis solution with 2.0 mEq/L potassium, 3.0 to 3.5 mEq/L calcium concentrations, 35 mEq/L HCO3, and 140 mEq/L sodium. The longitudinal data of each patient in the program for 1, 2, 3, 4, and 5 years were compared to the same patient's pre‐NHHD data. There were 25 patients in the program for 1 year, 19 patients for 2 years, 14 patients for 3 years, 6 patients for 4 years, and 4 patients for 5 years.

Results: Statistically significant improvement occurred in all five groups' need for antihypertensive medications and phosphate binders, SF36 scores, calcium/phosphorus product, blood pressure, number of hospital admissions, and number of days of stay in the hospital. The mortality rate was 2.4% deaths per patient‐year with a 95% confidence interval of 0.9% to 9.4%.

Conclusions: In a longitudinal study, NHHD showed significant improvements in patient secondary outcomes. The improvement in these secondary outcomes was associated with an improvement in mortality rate.
Peptide‐Coated Vascular Grafts: An In Vivo Study in Sheep
Authors: Hill A. , Li C. , Tio F. , Imran M.
Published: December 2004

Background:  The purpose of this study was to evaluate the amount of neo‐intimal tissue in‐growth present at the arterial and venous sides of the anastomosis and the degree of endothelial cell lining of the graft lumen in sheep using commercial vascular grafts coated with the P15 cell‐binding peptide.

Methods:  ePTFE vascular grafts were coated with the cell‐binding P15 peptide using a newly developed plasma surface treatment method. 4 P15‐treated grafts and 2 control grafts were implanted as arterio‐venous fistulas between the femoral artery and vein and between the carotid artery and jugular vein in 2 sheep. 1 animal was euthanized after 14 days and the other animal after 28 days. The grafts along with the connecting arteries and veins were explanted and evaluated for the length of tissue in‐growth along the luminal surface of the ePTFE graft from the anastomosis at the arterial and venous sides. Intimal thickness was carefully measured. Scanning electronic microscopy (SEM) was used to confirm the endothelial cell lining.

Results:  The study showed a significant difference (p < 0.05) in intimal thickness between the coated and uncoated grafts in the venous side of the anastomosis. The average intimal thickness of coated samples (551 μm) was 3 times thinner than that of uncoated ones (1657 μm). The endothelial cell lining appeared to be thicker, and its coverage was more uniform for the peptide‐coated grafts than the uncoated ones. Overall, there was more neo‐intimal tissue in‐growth at the venous side than the arterial side of the anastomosis. The intima at the venous side was also thicker and more bulky compared to the arterial side.

Conclusion:  This study has demonstrated that P15‐coated ePTFE grafts had less intimal tissue in‐growth developed at the venous side of the anastomosis than the uncoated ePTFE grafts. The degree of endothelial cell lining for coated samples was also higher than uncoated ones, which is consistent with our in vitro studies using human umbilical vein endothelial cells. P15‐coated ePTFE graft materials had significantly improved cell adhesion, proliferation, and migration in vitro over uncoated ePTFE.
Is There Any Relationship between Serum Levels of IL‐10 and Atherosclerosis in Hemodialysis Patients?
Authors: Seyrek N. , Balal M. , Karayaylali I. , Paydas S. , Aikimbaev K. , Cetiner S. , Seydaoglu G.
Published: December 2004

Background:  Cardiovascular complications due to atherosclerosis (AS) are the major cause of mortality in hemodialysis (HD) patients. Inflammation may play an important role in the development of AS. Several studies have demonstrated the association of acute‐phase proteins and cytokines with AS in the general population and in HD patients. Interleukin‐10 (IL‐10) is an anti‐inflammatory cytokine. The aim of study was to compare serum levels inflammatory and anti‐inflammatory indicators in HD patients according to the presence or absence of AS.

Methods:  Thirty‐three HD patients were enrolled. AS was defined as the detection of plaques by Doppler ultrasonography. The patients were subgrouped according to the presence or absence of plaques. Serum levels of IL‐1, IL‐2, IL‐6, IL‐10, C‐reactive protein (CRP) and tumor necrosis factor‐α (TNF‐α) were measured. The factors for AS such as age, gender, hypertension, hyperlipidemia, and HD duration were also evaluated.

Results:  We found that the patients with AS had significantly higher hs‐CRP and lower IL‐10. Blood pressure values were also increased in patients with AS. Additionally, there was an increased correlation between CRP and IL‐10.

Conclusions:  AS(+) patients undergoing HD had low serum levels of anti‐inflammatory cytokine IL‐10 and high serum levels of hs‐CRP. These results may suggest that the limitation of anti‐inflammatory response in atherosclerotic uremic patients is a triggering or contributing factor for AS.
Importance of Phosphate Control for Restoration of Vascular Responsiveness in End‐Stage Renal Disease Patients Converted to Nocturnal Hemodialysis
Authors: Chan C.T. , Harvey P.J. , Pierratos A. , Miller J.A. , Floras J.S.
Published: December 2004

Hyperphosphatemia and poor uremia control are established cardiovascular risk factors in patients with end‐stage renal disease (ESRD) associated with impaired endothelial dependent and independent vasodilation (EDV and EIV). Nocturnal hemodialysis [6 × 8 h/week] augments dialysis dose and offers normal phosphate (Pi) balance. We hypothesized that NHD would restore EDV (endothelial function) and EIV (vascular smooth muscle cell function) by simultaneously improving uremia and Pi control. 2 groups of ESRD patients (mean age 41 ± 2 years) stratified according to their baseline plasma Pi levels (normal Pi <1.8 mM, high Pi >1.8 mM) were studied. Dialysis dose (Kt/V per session), plasma Pi, blood pressure (BP) and brachial artery responses to reactive hyperemia (EDV), and sublingual nitroglycerin (EIV) were examined before, 1 and 2 months after conversion from conventional hemodialysis (CHD) [3 × 4 h/week] to NHD. After 2 months, NHD increased dialysis dose (from 1.24 ± 0.06 to 2.04 ± 0.08; p = 0.02) and lowered BP (from 140 ± 5/82 ± 3 to 119 ± 1/71 ± 3, p = 0.01) in all patients. In patients with adequate Pi control during CHD, EDV was normalized after 1 month of NHD. In contrast, in the high Pi group, 1 month of NHD was sufficient to reduce plasma phosphate levels, but 2 months of NHD was required for EDV to improve.

Variables
Normal Pi (n=10) CHD
NHD (1month)
NHD (2months)
High Pi (n=8) CHD
NHD (1month)
NHD (2 months)

Pi (mM)
−1.44 ± 0.09
1.08 ± 0.07*
1.14 ± 0.11*
2.52 ± 0.3
1.40 ± 0.17*
1.26 ± 0.05*

EDV (%)
−3.4 ± 2.7
7.5 ± 1.9*
7.6 ± 1.3*
−1.7 ± 1.3
0.37 ± 1.6†
 8.8 ± 1.2*

EIV (%)
−8.2 ± 4.8
10.3 ± 2.0
15.1 ± 2.0*
5.1 ± 1.1
 6.6 ± 0.8†
16.9 ± 1.7*

p < 0.05 from values during CHD.

p < 0.05 between the normal and high Pi groups.

Correction of uremia without normalization of plasma Pi is insufficient to improve EDV. The time course over which this improvement in vascular responsiveness occurs is delayed in hyperphosphatemic patients, suggesting that improvement in endothelial and vascular smooth muscle cell function requires restoration of normal intracellular Pi balance.
Unphysiology Is the Major Factor Influencing Cardiovascular Instability during Hemodialysis
Authors: Kjellstrand C.M. , Ing T. , Blagg C.R.
Published: December 2004

Background:  Hemodialysis is often complicated by cardiovascular instability (CVI). We studied factors contributing to this problem during 720 hemodialyses (HDs) in 20 patients; 480 dialyses were 6/week and 240 were 3/week.

Methods:  Dependent variables were increase in pulse rate (PR) and maximal (MAX) and overall (OV) fall of systolic blood pressure (BP). Independent variables were dialyses/week (DIAL), ultrafiltration (Uf), % of body weight (BW), pre‐post BUN (ΔBUN), time on dialysis (T), speed of dialysis (K/V in mL min–1 kg–1 BW), target‐postdialysis BW (Ta‐Po BW), Kt/V, ΔPO4, Δbicarbonate, Δpotassium, ΔBUN, an ‘unphysiology index’ summing up changes in electrolytes, and BUN and BW during dialysis (UPI). The relations were analyzed by backward multiple regression analysis.

Results:  PR increased 0.5 ± 11/min; MAX BP fall was 23 ± 17 mmHg; OV BP fall was 12 ± 19 mmHg. In multiple stepwise backward regression analysis, independents in order of importance: PR = 38 – DIAL × 4 + T × 0.1 + Uf × 1.8 +ΔPO4 × 1.8 – UPI× 0.2 – K/V × 2, r = 0.30, p < 0.0001; MAX BP = UPI × 0.4 – ΔBUN × 0.3 + ΔPO4 × 2.6 + 11, r = 0.34, p < 0.0001; OV BP = UPI × 0.4 – ΔBUN × 0.3 +ΔPO4 × 2.7 + 1, r = 0.33, p < 0.0001.

Conclusion:  To prevent BP fall and tachycardia during hemodialysis, the most important factor to decrease is unphysiology, i.e., the oscillations in electrolytes, fluid spaces, and osmolality that occur during dialysis. The best way to do this is to dialyze patients daily. An unexpected finding worthy of further investigation was the large detrimental influence of ΔPO4 on CVI.
Mortality Risk between For‐Profit and Not‐For‐Profit Dialysis Facilities
Authors: Foley R.n. , Fan Q. , Gilbertson D.t. , Ebben J.p. , Weinhandl E. , Collins A.J.
Published: December 2004

Background:  A recent meta‐analysis suggested that the relative risk of mortality is 8% higher in private for‐profit hemodialysis (HD) centers than private not‐for‐profit HD centers (Devereaux et al. JAMA 2002; 288: 2449).

Objective:  To assess the association between dialysis center profit status and mortality using USRDS data in the current era under DOQI guidelines.

Methods:  We studied incident HD patients from 1995 to 2000 who had Medicare as primary payer during the 4th through 6th month after ESRD initiation. Patients who died or underwent transplant during the 6 months after initiation were excluded. Primary dialysis provider was determined from the majority provider during the 6 months after initiation. Patient mortality for the following 12 months was evaluated via Cox regression, which adjusted for age, gender, primary cause of ESRD, race, cumulative hospital days, and comorbidity measures, which were assessed through both Medicare claims during the entry period and the Medicare Evidence form 2728. Patients were followed up until transplantation, death, or completion of the 12 months.

Results:  189,932 patients receiving HD during 1995–2000 were included in our analysis. The adjusted mortality rate was 271.6 per 1000 person‐years at the private for‐profit centers and 272.2 at the private not‐for‐profit centers. The mortality risk relative to private for‐profit vs. not‐for‐profit centers was 1.009 (95% CI, 0.978–1.042; p = 0.558). Sub‐analyses that excluded hospital‐based facilities showed similar results. Although public not‐ for‐profit facilities were excluded from the analysis, a sub‐analysis performed with these also showed similar results.

Conclusion:  Our results suggest that dialysis center profit status was not associated with mortality. This lack of association was found in the combined 1995–2000 population and in separate models for each year. Freestanding vs. hospital‐based and public vs. non‐public facility had no impact on the results.
Phosphorus‐Enriched Hemodialysis for the Treatment of Hypophosphatemia in a Patient with Severe Lithium Poisoning
Authors: Chebrolu S.b. , Chaudhury S. , Bidani A. , Kjellstrand C.m. , Ing T.s.
Published: December 2004

Severe lithium poisoning requires intensive and prolonged hemodialysis (HD) treatment in addition to supportive therapy. Aggressive dialytic therapy can bring about hypophosphatemia, especially, in those patients who are normo‐ or hypophosphatemic to begin with. We report here the use of phosphorus (P)‐enriched HD in a hypophosphatemic patient with lithium poisoning. A 58‐year‐old woman with a long history of bipolar disorder treated with chronic lithium therapy presented with progressively worsening confusion and incoherent speech. She was noted to be confused with a labile mood. The serum levels were lithium 3.6 mM, creatinine 1.7 mg/dL, Na 136 mM, K 4.2 mM, CO2 21 mM, BUN 23 mg/dL, and P 2.1 mg/dL. After a conventional, 4‐h HD session, she became more hypophosphatemic with a P level of 1.8 mg/dL. A P‐enriched dialysate, prepared by adding a Fleet® oral saline laxative preparation (containing NaH2PO4.H2O and Na2HPO4.7H2O) to the “base concentrate” of a dual concentrate, bicarbonate‐based dialysate generating system to obtain a final dialysate containing 3 mg (0.97 mM) of P/dL was used. She underwent 3 subsequent HD sessions using this P‐enriched dialysate, followed by normalization of the serum levels of both lithium and P.

Our data suggest that hypophosphatemic patients suffering from severe lithium poisoning requiring intensive HD therapy and becoming more hypophosphatemic as a result of the dialysis treatment can be further dialyzed with a P‐enriched dialysate both to treat the lithium poisoning and to rectify the hypophosphatemia. In general, the use of such dialysates can play an important role in the prevention and treatment of dialysis‐induced hypophosphatemia.

Day
Length of HD (h)
Lithium level predialysis (mM)
Lithium level postdialysis (mM)
P level in the final dialysate (mg/dL)
Serum P level postdialysis (mg/dL)

1
4 (1st session)
3.4
0.87
0
1.8

4 (2nd session)
1.53
0.59
3
3.0

2
4 (3rd session)
1.13
0.59
3
3.3

3
4 (4th session)
0.69
0.52
3
3.4