bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil 13C–15N dynamics in an N2‐fixing clover system under long‐term exposure to elevated atmospheric CO2
Authors: Van Groenigen Kees‐Jan , Six Johan , Harris David , Blum Herbert , Van Kessel Chris
Published: December 2004

Reduced soil N availability under elevated CO2 may limit the plant's capacity to increase photosynthesis and thus the potential for increased soil C input. Plant productivity and soil C input should be less constrained by available soil N in an N2‐fixing system. We studied the effects of Trifolium repens (an N2‐fixing legume) and Lolium perenne on soil N and C sequestration in response to 9 years of elevated CO2 under FACE conditions. 15N‐labeled fertilizer was applied at a rate of 140 and 560 kg N ha−1 yr−1 and the CO2 concentration was increased to 60 Pa pCO2 using 13C‐depleted CO2. The total soil C content was unaffected by elevated CO2, species and rate of 15N fertilization. However, under elevated CO2, the total amount of newly sequestered soil C was significantly higher under T. repens than under L. perenne. The fraction of fertilizer‐N (fN) of the total soil N pool was significantly lower under T. repens than under L. perenne. The rate of N fertilization, but not elevated CO2, had a significant effect on fN values of the total soil N pool. The fractions of newly sequestered C (fC) differed strongly among intra‐aggregate soil organic matter fractions, but were unaffected by plant species and the rate of N fertilization. Under elevated CO2, the ratio of fertilizer‐N per unit of new C decreased under T. repens compared with L. perenne. The L. perenne system sequestered more 15N fertilizer than T. repens: 179 vs. 101 kg N ha−1 for the low rate of N fertilization and 393 vs. 319 kg N ha−1 for the high N‐fertilization rate. As the loss of fertilizer‐15N contributed to the 15N‐isotope dilution under T. repens, the input of fixed N into the soil could not be estimated. Although N2 fixation was an important source of N in the T. repens system, there was no significant increase in total soil C compared with a non‐N2‐fixing L. perenne system. This suggests that N2 fixation and the availability of N are not the main factors controlling soil C sequestration in a T. repens system.
Elevated CO2decreases leaf fluctuating asymmetry and herbivory by leaf miners on two oak species
Authors: Cornelissen Tatiana , Stiling Peter , Drake Bert
Published: December 2004

Fluctuating asymmetry (FA) represents small, random variation from symmetry in otherwise bilaterally symmetrical characters. Significant increases in FA have been found for several species of plants and animals in response to various stresses, including environmental and genetic factors. In this study, we investigated the effects of elevated CO2on leaf symmetry of two oak species,Quercus geminataandQ. myrtifolia, and the responses of three species of leaf miners and one gall‐making species to random variation in leaf morphology. Leaf FA decreased with an increase in CO2concentration. There were fewer asymmetric leaves and lower levels of asymmetry on leaf width and leaf area on elevated CO2compared with ambient CO2. Leaf miners responded to leaf asymmetry, attacking asymmetric leaves more frequently than expected by chance alone. Differences in secondary chemistry and nitrogen (N) content between symmetric and asymmetric leaves may be responsible for these results due to lower levels of tannins and higher levels of N found on asymmetric leaves ofQ. myrtifoliaandQ. geminata.
Reduced water repellency of a grassland soil under elevated atmospheric CO2
Authors: Newton Paul C. D. , Carran R. A , Lawrence Erin J.
Published: December 2004

Water repellency is a widespread characteristic of soils that can modify soil moisture content and distribution and is implicated in important processes such as aggregation and carbon sequestration. Repellency arises as a consequence of organic matter inputs; as elevated atmospheric CO2 is known to modify such inputs, we tested the repellency of a grassland soil after 5 years of exposure to elevated CO2 in a free air carbon dioxide enrichment experiment. Using a water droplet penetration time test, we found a significant reduction in repellency at elevated CO2 in samples at field moisture content. As many of the processes potentially influenced by repellency have been shown to be modified at elevated CO2 (e.g. soil aggregation, C sequestration, recruitment from seed), we suggest that further exploration of this phenomenon could enhance our understanding of CO2 effects on ecosystem function. The mechanism responsible for the change in repellency has not been identified.
Simulation and scaling of temporal variation in gross primary production for coniferous and deciduous temperate forests
Authors: Wang Q. , Tenhunen J. , Falge E. , Bernhofer Ch. , Granier A. , Vesala T.
Published: December 2004

Observations of ecosystem net carbon dioxide exchange obtained with eddy covariance techniques over a 4‐year period at spruce, beech and pine forest sites were used to derive time series data for gross primary production (GPP) and ecosystem respiration (Reco). A detailed canopy gas exchange model (PROXELNEE) was inverted at half‐hour time step to estimate seasonal changes in carboxylation capacity and light utilization efficiency of the forest canopies. The parameter estimates were then used further to develop a time‐dependent modifier of physiological activity in the daily time step gas exchange model of Chen et al. (1999), previously used for regional simulations in BOREAS. The daily model was run under a variety of assumptions and the results emphasize the need in future analyses: (1) to focus on time‐dependent seasonal changes in canopy physiology as well as in leaf area index, (2) to compare time courses of physiological change in different habitats in terms of recognizable cardinal points in the seasonal course, and (3) to develop methods for utilizing information on seasonal changes in physiology in regional and continental carbon budget simulations. The results suggest that the daily model with appropriate seasonal adjustments for physiological process regulation should be an efficient tool for use in conjunction with remote sensing for regional evaluation of global change scenarios.
Summer warming and increased winter snow cover affect Sphagnum fuscum growth, structure and production in a sub‐arctic bog
Authors: Dorrepaal Ellen , Aerts Rien , Cornelissen Johannes H. C. , Callaghan Terry V. , Van Logtestijn Richard S. P.
Published: December 2004

Sphagnum mosses form a major component of northern peatlands, which are expected to experience substantially higher increases in temperature and winter precipitation than the global average. Sphagnum may play an important role in the responses of the global carbon cycle to climate change. We investigated the responses of summer length growth, carpet structure and production in Sphagnum fuscum to experimentally induced changes in climate in a sub‐arctic bog. Thereto, we used open‐top chambers (OTCs) to create six climate scenarios including changes in summer temperatures, and changes in winter snow cover and spring temperatures. In winter, the OTCs doubled the snow thickness, resulting in 0.5–2.8°C higher average air temperatures. Spring air temperatures in OTCs increased by 1.0°C. Summer warming had a maximum effect of 0.9°C, while vapor pressure deficit was not affected. The climate manipulations had strong effects on S. fuscum. Summer warming enhanced the length increment by 42–62%, whereas bulk density decreased. This resulted in a trend (P<0.10) of enhanced biomass production. Winter snow addition enhanced dry matter production by 33%, despite the fact that the length growth and bulk density did not change significantly. The addition of spring warming to snow addition alone did not significantly enhance this effect, but we may have missed part of the early spring growth. There were no interactions between the manipulations in summer and those in winter/spring, indicating that the effects were additive. Summer warming may in the long term negatively affect productivity through the adverse effects of changes in Sphagnum structure on moisture holding and transporting capacity. Moreover, the strong length growth enhancement may affect interactions with other mosses and vascular plants. Because winter snow addition enhanced the production of S. fuscum without affecting its structure, it may increase the carbon balance of northern peatlands.
Long‐term ecosystem level experiments at Toolik Lake, Alaska, and at Abisko, Northern Sweden: generalizations and differences in ecosystem and plant type responses to global change
Authors: Van Wijk M. T. , Clemmensen K. E. , Shaver G. R. , Williams M. , Callaghan T. V. , Chapin F. S. , Cornelissen J. H. C. , Gough L. , Hobbie S. E. , Jonasson S. , Lee J. A. , Michelsen A. , Press M. C. , Richardson S. J. , Rueth H.
Published: December 2004

Long‐term ecosystem‐level experiments, in which the environment is manipulated in a controlled manner, are important tools to predict the responses of ecosystem functioning and composition to future global change. We present the results of a meta‐analysis performed on the results of long‐term ecosystem‐level experiments near Toolik Lake, Alaska, and Abisko, Sweden. We quantified aboveground biomass responses of different arctic and subarctic ecosystems to experimental fertilization, warming and shading. We not only analysed the general patterns but also the differences in responsiveness between sites and regions. Aboveground plant biomass showed a broad similarity of responses in both locations, and also showed some important differences. In both locations, aboveground plant biomass, particularly the biomass of deciduous and graminoid plants, responded most strongly to nutrient addition. The biomass of mosses and lichens decreased in both locations as the biomass of vascular plants increased. An important difference between the two regions was the smaller positive aboveground biomass response of deciduous shrubs in Abisko as compared with Toolik Lake. Whereas in Toolik Lake Betula nana increased its dominance and replaced many of the other plant types, in Abisko all vascular plant types increased in abundance without major shifts in relative abundance. The differences between the responses of the dominant vegetation types of the Toolik Lake region, i.e. tussock tundra systems, and that of the Abisko region, i.e. heath systems, may have important implications for ecosystem development under expected patterns of global change. However, there were also large site‐specific differences within each region. Several potential mechanistic explanations for the differences between sites and regions are discussed. The response patterns show the need for analyses of joint data sets from many regions and sites, in order to uncover common responses to changes in climate across large arctic regions from regional or local responses.
The SAFARI 2000 – Kalahari Transect Wet Season Campaign of year 2000
Authors: Shugart H. H. , Macko S. A. , Lesolle P. , Szuba T. A. , Mukelabai M. M. , Dowty P. , Swap R. J.
Published: December 2004

Over 50 scientists from eight different countries coordinated research efforts in the Kalahari sand mass in Zambia and Botswana during the 2000 wet season as a part of the Southern African Regional Science Initiative – Kalahari Transect Wet Season Campaign (S2K‐KT Wet Season Campaign). The work focused on change in ecological processes along the International Geosphere–Biosphere Programme‐designated Kalahari Transect (KT). Topics included ecosystem structure, function, biogeochemistry, and modeling at the patch, landscape and regional scale. The KT of southern and central Africa follows a sharp precipitation gradient within an otherwise climatically and geographically similar region that contains a widely distributed, physically uniform soil and relatively little variation in elevation. This paper outlines the focus of the SAFARI 2000 research campaign as it relates to this study area and provides references to archived data sets generated during the study. It also describes vegetation patterns, climate, and 2000 wet season meteorological conditions for the region.
Genetic variation in Sanguisorba minor after 6 years in situ selection under elevated CO2
Authors: Wieneke Silvia , Prati Daniel , Brandl Roland , Stöcklin Jürg , Auge Harald
Published: December 2004

Genetic variation within plant species in their response to elevated CO2 could be important for long‐term changes in plant community composition because it allows for selection of responsive genotypes. Six years of in situ CO2 enrichment in a temperate grassland offered a unique opportunity to investigate such microevolutionary changes in a common herb of that plant community, Sanguisorba minor. Plants were grown from seeds collected at the end of a 6‐year treatment in either ambient or elevated CO2. The resulting seedlings were grown under ambient or elevated CO2 and with or without interspecific competition by Bromus erectus in the greenhouse for two seasons. The effect of competition was included because we expected selection under elevated CO2 to favour increased competitive ability. Elevated CO2 in the greenhouse and competition both caused a significant reduction of the total dry mass in S. minor, by 12% and 40%, respectively, with no interaction between CO2 and competition. Genetic variation in all traits was substantial. Seed families responded differently to competition, but the family × greenhouse CO2 interaction was rather weak. There was no main effect of the field CO2 treatment on any parameter analysed in the greenhouse. However, the field CO2 treatment did significantly interact with the greenhouse CO2 treatment for the cumulative number of leaves, suggesting microevolutionary change in this plant trait. Families from ambient field CO2 produced fewer leaves under elevated greenhouse CO2, whereas families from elevated field CO2 retained constant number of leaves in either greenhouse CO2 treatment. Since this resulted in increased litter production of the families from elevated field CO2 under elevated greenhouse CO2, the microevolutionary response should, in turn, affect ecosystem functions through dry matter recycling.
Secondary prophylaxis therapy: what are the benefits, limitations and unknowns?
Authors: Valentino L. A.
Published: December 2004

Summary.  Prophylaxis is widely recommended for the management of severe haemophilia A. Adoption of this approach has varied from country to country, and notably in the US prophylaxis is currently administered in fewer than one‐half of severe cases. One implication is that a substantial segment of the severe haemophilia. A population will only be able to reap the potential benefits of prophylaxis if administered in the form of secondary prophylaxis. This therapeutic alternative has been less extensively investigated than primary prophylaxis, but nevertheless sufficient evidence has been reported to allow an assessment of the benefits and limitations of secondary prophylaxis. This evidence addresses the use of secondary prophylaxis in three contexts: (i) early secondary prophylaxis; (ii) delayed secondary prophylaxis and (iii) secondary prophylaxis in adults. In patients receiving early secondary prophylaxis studies in Sweden, the Netherlands, the UK and the US have demonstrated a reduction in the frequency of bleeding episodes and a subsequent low incidence of arthropathy. Additional reported benefits consist of reduced emergency room visits and hospitalizations. However, secondary prophylaxis is associated with an increased risk of the eventual development of arthropathy compared with primary prophylaxis. When delayed until school age or adolescence or until the development of frequent bleeding episodes under on‐demand treatment, secondary prophylaxis generally appears to be unable to reverse all existing or developing joint damage. Nevertheless, multiple studies have shown that this therapy can retard further joint deterioration, reduce the frequency of haemorrhage, hospitalization and missed school days, improve physical function and capacity for self care, lessen restrictions on activities, reduce pain and enhance quality of life. Secondary prophylaxis in adults has been shown effective in reducing bleeding episodes. Adults under secondary prophylaxis can also experience improvements in joint condition, functional capacity and quality of life and a reduction in pain. Irrespective of age at initiation, long‐term secondary prophylaxis appears to reduce the frequency of bleeding episodes even in patients with existing target joints whose bleeding diathesis persists during the early phases of secondary prophylactic therapy. In light of its potential benefits for substantial numbers of patients with severe haemophilia A, secondary prophylaxis should be considered to as a therapeutic option for patients not receiving primary prophylaxis.
Bleeding manifestations in males with von Willebrand disease
Authors: Ziv O , Ragni M. V.
Published: December 2004

Summary.  von Willebrand disease (vWD) is the most common congenital bleeding disorder in the USA, affecting 1–3% of the population. Previously characterizing the bleeding symptoms in females with type 1 vWD, we evaluated 42 males with type 1 vWD, mean age 16 years (1–64), of whom 24 (57%) presented with bleeding symptoms. The most common initial symptom was postoperative bleeding (26%). The most common bleeding symptoms ever were epistaxis (53%), bruising (50%), postoperative bleeding (47%), haematomas (29%) and oral bleeding (29%). Of postoperative bleeding, ear/nose/throat (44%), dental (17%) and circumcision bleeding (22%) occurred at a median 10 years of age, despite a previous bleeding or family history in 89%. Complications included anaemia in five (12%), neurological sequelae after subdural haematoma and tonsillectomy in two (5%), transfusion‐associated hepatitis C in two (5%) and degenerative joint disease after traumatic haemarthroses in one (2%). The bleeding time (BT) was prolonged in 83%, and the ristocetin cofactor (vW:RCoF) and factor VIII (FVIII:C) decreased in 64% and 43%, respectively. Haemarthroses and haematoma formation were associated with a longer activated partial thromboplastin time (APTT) (P < 0.05), and anaemia with a lower FVIII:C (P < 0.05). In 81%, a haemostatic response occurred with 1‐8 deamino‐d‐arginine vasopressin (DDAVP), although, in 13%, surgical intervention was also required to achieve haemostasis. Postoperative bleeding could have been avoided in 89%, if a preoperative past bleeding history or family history had been obtained, and, in at least 94%, if a preoperative BT and APTT had also been performed. The failure to avoid postoperative bleeding and related complications in patients with vWD by taking a personal and family bleeding history constitutes a major public health problem.
Falkland Islands biogeography: converging trajectories in the South Atlantic Ocean
Authors: McDowall R. M.
Published: December 2004

Aim This paper describes the biogeographical setting of the Falkland Islands, in the context of the relationships of the islands’ biota to other sub‐Antarctic/cold temperate lands.

Location The analysis focuses primarily on the Falklands biota, and explores its relationships to those of Patagonian South America and South Africa, other southern lands and the islands of the sub‐Antarctic Pacific, Indian and Atlantic Oceans.

Methods The study derives largely from literature sources on the biota and geological history of the Falkland Islands.

Results The animals and plants known from the Falkland Islands exhibit strong affinities with those of Patagonian South America, and especially Tierra del Fuego; additional affinities are with various remote islands of the sub‐Antarctic, as well as New Zealand and to a lesser extent Australia; often these are shared with Patagonia. While the biotic affinities might be interpreted, by some, as indicating a former Gondwanan/South American geological connection of the Falklands, geological evidence points to the Falklands formerly having a land connection to south‐eastern South Africa. Only faint hints of a South African biotic connection remain. The historical biotic and geological connections of the Falklands thus conflict. Moreover, the Falklands biota is so strongly Patagonian that derivation of that biota is best seen as resulting from dispersal, much of it probably recent. This dispersal biota appears to have replaced, and perhaps displaced, the South African biota present on the islands as they detached from South Africa and drifted across the south Atlantic Ocean, as it opened up as South America and Africa drifted apart.
Vegetation establishment, succession and microsite frost disturbance on glacier forelands within patterned ground chronosequences
Authors: Haugland Jake E. , Beatty Susan W.
Published: December 2004

Aim The impact of microscale frost disturbance on vegetation colonization and successionary trends was examined within patterned ground features of Little Ice Age chronosequences. The goal was to investigate and compare vegetation response to micro‐site frost disturbance with that of previous studies done at a coarser landscape scale.

Location The study sites occur on Little Ice Age glacier forelands within Jotunheimen, Norway (61°–62° N). The forelands of the glaciers Slettmarkbreen, Styggedalsbreen and Vestre Memurubreen have been well studied providing chronological controls for landscape studies. Sorted patterned ground features are found within the chronosequences, typically declining with frost intensity and disturbance with increasing terrain age.

Methods Micro‐plots (8.3 × 8.3 cm) were placed at the inner borders and centres of patterned ground features. Species were identified and per cent species cover and per cent cover of life‐form category were noted. Nonparametric Kruskal–Wallis and Mann–WhitneyU‐tests were used to test for differences between percent cover of life‐form categories within patterned ground features as well as to identify thresholds of successional change across the chronosequences.

Results Significant relationships between life‐from groups and patterned ground positions of varying ages were deduced using nonparametric statistics. Findings were then used to discuss trends of succession within patterned ground features and across the chronosequences. Vegetation establishment occurs at the border positions of young (< 30 years) patterned ground features. With time and distance from the ice margin, vegetation encroaches inwards toward the disturbed centres. Succession within patterned ground exhibits several stages: (1) bryophytes/crusts and lichens, (2) grasses/sedges and (3) woody shrubs. The occurrence of forbs was sporadic and generally non‐significant.

Main conclusions Frost disturbance in patterned ground appears to delay successional trends of vegetation communities when compared with previous studies on ‘stable’ terrain, producing micro‐site lag effects. These small patches of disturbed ground are therefore important regarding vegetation assemblages across the landscape and are unlikely to be detected at the landscape scale.
Crystal structure of the cytotoxic bacterial protein colicin B at 2.5 Å resolution
Authors: Hilsenbeck Jacqueline L. , Park HaJeung , Chen Gregory , Youn Buhyun , Postle Kathleen , Kang ChulHee
Published: December 2004

Colicin B (55 kDa) is a cytotoxic protein that recognizes the outer membrane transporter, FepA, as a receptor and, after gaining access to the cytoplasmic membranes of sensitive Escherichia coli cells, forms a pore that depletes the electrochemical potential of the membrane and ultimately results in cell death. To begin to understand the series of dynamic conformational changes that must occur as colicin B translocates from outer membrane to cytoplasmic membrane, we report here the crystal structure of colicin B at 2.5 Å resolution. The crystal belongs to the space group C2221 with unit cell dimensions a = 132.162 Å, b = 138.167 Å, c = 106.16 Å. The overall structure of colicin B is dumbbell shaped. Unlike colicin Ia, the only other TonB‐dependent colicin crystallized to date, colicin B does not have clearly structurally delineated receptor‐binding and translocation domains. Instead, the unique N‐terminal lobe of the dumbbell contains both domains and consists of a large (290 residues), mostly β‐stranded structure with two short α‐helices. This is followed by a single long (≈ 74 Å) helix that connects the N‐terminal domain to the C‐terminal pore‐forming domain, which is composed of 10 α‐helices arranged in a bundle‐type structure, similar to the pore‐forming domains of other colicins. The TonB box sequence at the N‐terminus folds back to interact with the N‐terminal lobe of the dumbbell and leaves the flanking sequences highly disordered. Comparison  of  sequences  among  many  colicins has allowed the identification of a putative receptor‐binding domain.
Lesional T‐cell subset in post‐kala‐azar dermal leishmaniasis
Authors: Rathi Sanjay K. , Pandhi Ravindra K. , Chopra Prem , Khanna Neena
Published: December 2004

Background  The pathogenesis of post‐kala‐azar dermal leishmaniasis (PKDL) is ill understood. This study was carried out to find the percentage of T‐helper and T‐suppressor cells in lesional tissue and their probable role in the pathogenesis of PKDL.

Methods  An immunoperoxidase monoclonal antibody technique was used to characterize and quantify the subsets of T lymphocytes in the infiltrate in 25 patients with PKDL.

Results  The ratio of T‐helper to T‐suppressor cells was 0.87 in hypopigmented macules and 0.85 in nodule and/or plaque lesions of PKDL.

Conclusions  In this study, there was a definite preponderance of T‐suppressor cells over T‐helper cells in both types of skin lesions of PKDL. Further studies should be undertaken on larger numbers of patients to compare T‐cell subsets both in skin lesions and the circulation, in order to determine the pathogenesis of PKDL.
Acanthosis nigricans in a plaque of scleredema on the back of a diabetic patient: A case report
Authors: Lamba Sumedha , Krishtul Anna , Tan Mei‐Heng , Lebwohl Mark G.
Published: December 2004

Acanthosis nigricans (AN) and scleredema are two skin conditions that have been reported in association with diabetes mellitus. Few cases associating scleredema and AN have been reported. A literature search did not reveal any reports of diabetic patients developing AN on top of a scleredema plaque. Here we report a patient with diabetes mellitus who developed AN within the same indurated scleredema plaque.
Use of pimecrolimus cream 1% (Elidel®) in the treatment of atopic dermatitis in infants and children: the effects of ethnic origin and baseline disease severity on treatment outcome
Authors: Eichenfield Lawrence F. , Lucky Anne W. , Langley Richard G. B. , Lynde Charles , Kaufmann Roland , Todd Gail , Lindsley Linda , Barbier Nathalie , Felser James M.
Published: December 2004

Background  Pimecrolimus cream 1%, a cell‐selective inhibitor of inflammatory cytokines, has been shown to be effective in treating atopic dermatitis (AD). This report examines the effect of ethnic origin and baseline disease severity on treatment outcomes in pediatric patients with AD treated with pimecrolimus cream 1%.

Methods  The analysis included 589 patients aged 3 months to 17 years from three 6‐week, randomized, multicenter studies of similar design. Patients were treated with pimecrolimus cream 1% or vehicle twice daily. Efficacy, safety and tolerability in Caucasian and non‐Caucasian groups were compared. In addition, the effect of baseline disease severity on treatment outcome was investigated.

Results  A total of 321 Caucasian and 268 non‐Caucasian patients [Blacks, Asians and others (including Hispanics)] with mild, moderate or severe disease at baseline were included. Baseline characteristics were comparable between the pimecrolimus and vehicle control groups and between Caucasian and non‐Caucasian groups. Significantly higher efficacy [measured by Investigators’ Global Assessment and Eczema Area and Severity Index (EASI) scores] was achieved in the pimecrolimus‐treated group, compared with the vehicle group, irrespective of ethnic origin. Baseline disease severity had no effect on treatment outcome: patients with both mild and moderate AD responded well to pimecrolimus (absolute change from baseline in EASI score −2.60 and −5.48, respectively; both P < 0.001). Pimecrolimus cream 1% was safe and well tolerated in all ethnic groups and at all levels of disease severity.

Conclusions  Ethnic origin and baseline disease severity had no effect on treatment outcome with pimecrolimus cream 1% in patients with AD.
Prevalence of different skin conditions in an outpatients’ setting in north‐western Nigeria
Authors: Onayemi Olaniyi , Isezuo Simeon A. , Njoku Chibueze H.
Published: December 2004

Background  Information on skin diseases in north‐western Nigeria is scanty. We therefore conducted a prospective survey of 2611 new patients seen between August 1999 and July 2001 at the consultant medical/dermatology clinics of Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria.

Methods  The personal bio‐data of all consecutive patients with skin diseases were documented. They were examined and the diagnoses, which were based on the history of presentation and physical examination, were recorded. Bacteriologic, mycologic, and histologic confirmations were obtained as appropriate.

Results  Seven hundred and forty‐six patients (28.6%) had skin diseases. There were 407 male and 339 female patients aged between 0.17 and 90 years; the median age was 27 years. The median ages for male and female patients were 28 and 25 years, respectively. There were 900 skin diseases seen in the 746 patients. The majority of skin diseases were found amongst the younger age group, which represented over 85% of the patients. Infectious and parasitic skin diseases accounted for 44.4% of cases; eczema, acne, papulosquamous, and pigmentary skin disorders were observed in 14.1%, 7.0%, 6.4%, and 6.0% of cases, respectively.

Conclusions  Preventable skin diseases are common in north‐western Nigeria and predominantly affect individuals in the highly productive age group. Health education is therefore necessary to curb their spread, reduce the associated morbidity, and improve the health status of the population. A concerted effort should be made to train health workers in the diagnosis and treatment of the more common dermatologic conditions.
Pierre Marie–Bamberger syndrome (secondary hypertrophic osteoarthropathy)
Authors: Cannavò Serafinella P. , Guarneri Claudio , Borgia Francesco , Vaccaro Mario
Published: December 2004

A 55‐year‐old man presented to our Department with a 10‐year history of coarsening of the facial features. The soft tissue of the forehead had become progressively thickened and corrugated, resulting in marked, hard‐elastic asymmetrical convolutions involving the underlying eyelids, with partial reduction of the visual field (Fig. 1a,b). The patient also exhibited moderately prominent nasolabial folds, pachydermia of the hands and feet without nail changes, significant seborrhoea and palmo‐plantar hyperhydrosis.

(a) Normal aspect of the face (before pulmonary disease); (b) definitive changes in the face: asymmetrical convolutions of the forehead, hypertrophy of the eyelids and prominent nasolabial folds

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A 20‐year history of chronic obstructive pulmonary disease and emphysema, recently complicated by chronic cor pulmonale, and obesity were present. No family history of similar disorders was reported.

Routine blood tests, including full blood count, serum urea, creatinine, calcium, phosphorus, magnesium and electrolyte concentrations and tests of liver function, were normal. Hormonal investigations for testosterone, free triiodothyronine (FT3), free thyroxine (FT4), thyroid stimulating hormone (TSH) and growth hormone (GH) responses to stimulation and suppression tests were within normal limits, as was the evaluation of bone metabolism.

Haematoxylin‐eosin‐stained microsections prepared from a biopsy of the frontal region showed hypertrophic sebaceous glands, with a perifollicular nodule of fibrovascular hyperplasia, and hypertrophy of collagen; another specimen, obtained from the finger, displayed hyper‐orthokeratotic epidermis with few elastic fibers in the dermis, and a mild perivascular inflammatory infiltrate.

A radiological examination of the arms (Fig. 2) and legs revealed a tubular shape of the diaphysis of the long bones, with marked diffuse subperiostal new bone formation, resulting in cortical thickening of the distal ends. Soft tissue thickening around the joints was also evident.

Periostosis in bone diaphysis

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Age and palaeoenvironmental constraints on the genesis of the Yandi channel iron deposits, Marillana Formation, Pilbara, northwestern Australia*
Authors: MACPHAIL M. K. , STONE M. S.
Published: December 2004

Fossil pollen and spores preserved in organic‐rich claystones near the base of the palaeochannel hosting the Tertiary Yandi channel iron deposits (CID) provide an in situ constraint on the age of this world‐class orebody. This assemblage also aids understanding of the palaeoenvironment leading to the deposition and preservation of the host Marillana Formation. The provisional Early Oligocene age of claystones links the genesis of the Yandi CID to the profound disruption of global climates and oceanography at the Eocene–Oligocene transition (Terminal Eocene Event) and provides circumstantial evidence that ore formation was linked to the development of a warm south‐flowing proto‐Leeuwin Current along the Pilbara coast. It is likely that rainfall increased but remained strongly seasonal (monsoonal?) as global climates warmed during the Late Oligocene – Early Miocene. The same fossil evidence indicates that wood fragments, the iron‐oxide‐replaced remains of which are a significant component of cemented goethitic gravel making up CID, came from Casuarinaceae‐ and Myrtaceae‐dominated sclerophyll communities lining the channel banks. Increasingly dry conditions since the late Early Miocene Climatic Optimum are likely to have contributed to the preservation of CID at Yandi.
Contrasts in mantle structure beneath Australia: relation to Tasman Lines?
Authors: KENNETT B. L. N. , FISHWICK S. , READING A. M. , RAWLINSON N.
Published: December 2004

Surface‐wave tomography for the Australian region, using data mostly from portable seismic recorders, reveals a very strong contrast in seismic shear‐wave speed beneath central and western Australia and the east of the continent. Shear‐wave speeds faster than the continental average extend to at least 200 km depth in the cratonic zone to the west of 140°E. Along an approximately north–south line there is then an eastward step to thinner lithosphere (∼150 km thick) but still with fast shear‐wave speeds. A further more irregular transition to the east marks the transition to lowered shear‐wave speeds. The eastern transition at 75 km depth is in close agreement with the original Tasman Line, whereas the two more westerly transitions do not bear a simple relation to the more recent group of Tasman Lines defined from crustal information (outcrop and inferred geophysical trends). The westward transition to the thickest coherent lithosphere (near 140°E) may well mark the edge of the ancient core of the continent, but the current mantle structures must bear the scars of the breakups and reassembly that have created the current Australian continent.
Proterozoic cooling and exhumation of the northern central Halls Creek Orogen, Western Australia: constraints from a reconnaissance 40Ar/39Ar study
Authors: BODORKOS S. , REDDY S. M.
Published: December 2004

The Palaeoproterozoic Halls Creek Orogen preserves the most complete record of Barramundi (1880–1820 Ma) tectonism in northern Australia, but appears unaffected by the 1750–1500 Ma tectono‐magmatic activity that pervades other parts of the North Australian Craton. However, reliable geochronological data in the Halls Creek Orogen are largely restricted to U–Pb zircon and monazite determinations, and the history of post‐tectonic cooling in the crystalline basement remains poorly understood. A reconnaissance 40Ar/39Ar study has been undertaken in the northern central part of the orogen, where 1850–1845 Ma high‐grade metamorphism pre‐dated 1835–1825 Ma emplacement of the Mabel Downs Tonalite, and the subsequent development of the Highway Shear Zone under greenschist‐facies conditions. Hornblende and biotite 40Ar/39Ar results from the Mabel Downs Tonalite yield plateau ages of 1705 ± 5 Ma and 1546 ± 19 Ma, respectively, interpreted to record cooling through the temperatures 540 ± 40°C and 315 ± 45°C, respectively. These values yield slow time‐averaged cooling rates of 1.5 ± 0.5°C/106 years (1845–1705 Ma) and 1.4 ± 0.4°C/106 years (1705–1545 Ma). Variably discordant muscovite and biotite 40Ar/39Ar analyses from sheared leucogneiss and retrogressed pelitic migmatite in the Highway Shear Zone are difficult to interpret, although none record Palaeoproterozoic isotopic closure and most preserve evidence for resetting during Neoproterozoic (900–800 Ma) recrystallisation. In the absence of a reliable minimum age for the Yampi Orogeny (previously published pre‐1000 Ma K–Ar ages may be affected by unrecognised excess argon), the present 40Ar/39Ar data may reflect deformation associated with reactivation of the Highway Shear Zone during this event.
Effective collaboration enhances rural preceptorship training
Authors: Charleston Rosemary , Goodwin Val
Published: December 2004

ABSTRACT:  Preceptorship is a valuable strategy largely underestimated in its ability to influence nursing students’ attitudes and beliefs about mental health nursing. As a model, it has the potential to influence nursing practice, enhance clinical learning, promote recruitment and retention, and generate a more collaborative approach for nursing student supervision. The relationship is usually for a fixed and limited timeframe where the preceptor inspires and supports the growth and development of the student nurse, and encourages role socialization into the profession (

Morton‐Cooper & Palmer 2000

). The challenge for mental health services is to achieve success in the provision of effective preceptorship, ensure positive and rewarding clinical experiences for nursing students, and improve recruitment and retention rates for the service. These aims are substantially more difficult to achieve in the absence of quality education, training and support for preceptors. This paper describes the use of preceptorship training to address recruitment issues in a rural service, particularly the need for effective preceptorship at undergraduate level, which has been shown to have an impact on the willingness of new nursing graduates to enter the mental health nursing field. The design and delivery of the training programme is outlined, including details of the program evaluation and its subsequent impact on psychiatric nurses’ approach to and practice of preceptorship. Finally, the broader issue of the value of training nurses in larger groups, enlisting a critical mass of preceptors within an individual mental health service, is discussed.
Clients and facilitators’ experiences of participating in a Hong Kong self‐help group for people recovering from mental illness
Authors: Leung Judy , Arthur David G.
Published: December 2004

ABSTRACT:  The purpose of this study was to examine the effectiveness of self‐help groups in the rehabilitation of people recovering from mental illness. A qualitative approach was adopted, with individual interviews of 12 clients and four focus group interviews of 22 professionals and volunteers, in a Hong Kong self‐help organization. Three major categories emerged from the client interviews: the meaning of self‐help; experience of self‐help group involvement; and changes in life. The major categories which emerged from the focus groups were: the meaning of self‐help; therapeutic factors; therapeutic process; facilitators’ expectation; and difficulties encountered. Results indicated that self‐help group involvement provided positive experiences for the members and led to some changes in their lives which contribute to the rehabilitation of their illness. Meanwhile, the professionals’ and volunteers’ view of the use of self‐help groups was found to coincide with previous literature. Moreover, a spiritual dimension was expressed by all respondents as one of the factors that enhanced the group cohesiveness. It was concluded that self‐help group involvement is beneficial to psychiatric rehabilitation. Findings have implications for further utilization of self‐help groups for the people recovering from mental illness, as an alternative form of health care to complement the inadequacies in the present health care system.
Crack initiation from micro surface holes in bearings under rolling contact fatigue
Authors: KIDA K. , YAMAZAKI T. , SHIBATA M. , OGUMA N. , HARADA H.
Published: December 2004

Investigations concerning surface crack growth are necessary for understanding the mechanism of rolling contact fatigue (RCF) of bearings because the surface defects cause flaking failures. In the present work, micro holes were artificially made prior to the RCF tests and the initiation of the surface cracks from the micro holes was observed in order to find the key factors for understanding their features. Crack initiation directions were compared to the stress intensity factors calculated by a simple method based on the theory. The extent to which ‘contact pressure (wedge effect)’ and ‘contact stresses’ are applicable for understanding the correlations between the crack initiation directions and stress intensity factors is discussed. The crack initiation directions are strongly correlated to the stress intensity factors caused by the contact stresses alone. We concluded that the crack growth and initiation are dominated by stress intensity factors caused by contact stresses rather than the wedge effect.
On the Ekberg, Kabo and Andersson calculation of the Dang Van high cycle fatigue limit for rolling contact fatigue
Authors: CIAVARELLA M. , MAITOURNAM H.
Published: December 2004

Recently, various methods have been proposed to assess the risk of rolling contact fatigue failure by Ekberg, Kabo and Andersson, and in particular, the Dang Van multiaxial fatigue criterion has been suggested in a simple approximate formulation. In this note, it is found that the approximation implied can be very significant; the calculation is improved and corrected, and focused on the study of plane problems but for a complete range of possible friction coefficients. It is found that predicted fatigue limit could be much higher than that under standard uniaxial tension/compression for ‘hard materials’ than for ‘ductile materials.’ This is in qualitative agreement, for example, with gears' design standards, but in quantitative terms, particularly for frictionless condition, the predicted limit seems possibly too high, indicating the need for careful comparison with experimental results. Some comments are devoted to the interplay of shakedown and fatigue.
Slip behaviour near a grain boundary in high‐cycle fatigue of poly‐crystal copper
Authors: SUMIGAWA T. , KITAMURA T. , OHISHI K.
Published: December 2004

In order to investigate the characteristic slip behaviour near a grain boundary in high‐cycle fatigue, a high‐cycle fatigue test is carried out using a copper poly‐crystal specimen, which consists of several tens of grains. Seventeen persistent slip bands (PSBs) are observed along the grain boundaries. Their location and the activated slip system are different from those expected by the Schmid factor. After the fatigue test, the crystalline orientation and the three‐dimensional shape of each grain are specified by the repetition of polishing and observation by means of an orientation‐imaging microscope (OIM). A finite‐element method (FEM) analysis is also conducted for the specimen with the same orientation and shape of grains taking into account the anisotropy. This analysis reveals that the shear stress concentrates near the grain boundaries where the PSBs are formed. The activated slip systems predicted by the maximum resolved shear stress agree well with those observed in the fatigue experiment. Thus, the characteristic slip near the grain boundary in the poly‐crystal is governed by the concentrated resolved shear stress on the specific slip system due to the deformation constraint by neighbouring crystals.
Validation of procedures for fatigue life assessment of a steel pressure vessel
Authors: DE JESUS A. M. P. , RIBEIRO A. S. , FERNANDES A. A.
Published: December 2004

A full‐size pressure vessel, made of steel plate P355NL1 (EN 10028‐3), was tested under repeated internal pressure until its failure was observed. Also, four representative structural details of the tested pressure vessel were fatigue tested under load control with a stress ratio of R= 0. These structural details are basically two seam‐welded joints, namely a butt‐welded joint and a joggle‐welded joint, one plate attachment using fillet‐welded joints and a nozzle‐to‐plate connection. S–N curves were generated for these details based on both nominal and structural stresses. These curves are critically compared with those proposed in pressure vessel design codes like the ASME VIII – Division 2, the PD 5500 and the recently approved EN procedures, the EN 13445 standard. Finally, predictions of the fatigue life of the pressure vessel, obtained using the previously referred procedures and the experimentally derived design curves are critically compared with the observed life of the vessel.
The effect of bi‐modal and lamellar microstructures of Ti‐6Al‐4V on the behaviour of fatigue cracks emanating from edge‐notches
Authors: BENEDETTI M. , FONTANARI V.
Published: December 2004

This paper is aimed at evaluating the influence of bi‐modal and lamellar microstructures on the behaviour of small cracks emanating from notches in α+β titanium Ti‐6Al‐4V alloy. Pulsating four point bending tests were performed at a nominal stress ratio of 0.1 and a frequency of 15 Hz on double‐edge‐notched specimens. The conditions of initiation and early propagation of fatigue cracks were investigated at two relatively high nominal stress levels corresponding to 88 and 58% of the 0.2% material yield stress. Crack closure effects were measured by an extensometric technique and discussed. Variations in crack aspect ratio were determined and considered in the ΔK calculation. Corresponding results were discussed by considering the effect of the yielded region at the notch tip calculated by elastic–plastic finite element modelling of the fatigue tests. The importance of the bi‐modal and lamellar microstructures on the material damage was highlighted and correlated to the observed oscillations in the crack growth rate. The crack growth rate data obtained were compared with those measured using standard C(T) specimens (long crack).