bluuebunny/crossref_metadata_2025 huggingface dataset:
Elective orthopaedic surgery for inhibitor patients
Authors: Rodriguez‐Merchan E. C. , Wiedel J. D. , Wallny T. , Hvid I. , Berntorp E. , Rivard G‐E , Goddard N. J. , Querol F. , Caviglia H.
Published: September 2003

Summary.  We report on a series of 108 elective orthopaedic surgical procedures. It includes 88 radiosynoviortheses and 20 major orthopaedic procedures, performed on 51 patients at nine centres worldwide. The average age of patients was 28.5 years (range 5–40 years), and the average follow‐up time was 2 years (range 1–5 years). There were 82 good results, 15 fair and 11 poor. In the synoviorthesis group (41 patients, 88 synoviortheses) the average age was 14.3 years (range 5–40 years) and the average follow‐up was 6.5 years (range 1–10 years). There were 66 good results, 14 fair and eight poor. There were no complications. In the group of major orthopaedic procedures, the average age of the 10 patients was 32.5 years (range 27–40 years), and the average follow‐up was 2.3 years (range 1–5 years). There were 16 good results, one fair and three poor. Postoperative bleeding complications occurred in three of the 20 major orthopaedic procedures performed (15% complications rate). They occurred in three patients treated with insufficient doses of recombinant activated factor VII. Despite such complications, the study has shown that haemophilic patients with inhibitors requiring elective orthopaedic surgery (EOS) can undergo such procedures with a high expectation of success. In other words, EOS is now possible in haemophilic patients with inhibitors, leading to an improved quality of life for these patients. Thorough analysis of each case as part of a multidisciplinary team will allow us to perform elective orthopaedic procedures in patients with inhibitors.
HCV recovery from peripheral blood mononuclear cell culture supernatants derived from HCV–HIV co‐infected haemophilic patients with undetectable HCV viraemia
Authors: Baré P. , Massud I. , Belmonte L. , Corti M. , Villafañe M. , Pérez Bianco R. , De Tezanos‐pinto M. , De Bracco M. M. E. , Ruibal‐Ares B.
Published: September 2003

Summary.  Hepatitis C viraemia, in 38 human immunodeficiency virus positive (HIV+)/hepatitis C virus positive (HCV+) patients, was determined in haemophilic patients during the 4 years since initiation of highly active antiretroviral therapy (HAART). Six of 38 patients had persistently HCV‐negative viraemia for more than 2 years. No correlation between HCV‐negative viraemia and CD4+ T‐cell counts, HIV viral load, age, type or severity of haemophilia could be established. Reduced levels of HIV viral load and the immune reconstitution that follows the initiation of HAART were not enough to explain the disappearance of HCV from plasma. Individuals who cleared plasma HCV had significantly higher CD8+ T‐cell counts (P = 0.0013) (mean ± SE: 1153 ± 117.8cells μL−1) than those with HCV‐positive viraemia (819.1 ± 40.72 cells μL−1). Because HCV could maintain a low replication level in peripheral blood mononuclear cells (PBMC), we cultured PBMC of five of six patients with undetectable HCV viraemia. We found four of five HCV RNA‐positive cultures. The presence of HCV RNA in our cultures proved that these cells may be an important viral reservoir that could contribute to HCV recurrence in plasma even after long periods of negative viraemia. In summary, our results indicate that in spite of prolonged HCV‐negative plasma viraemia, HCV patients that are co‐infected with HIV may harbour replication‐competent HCV in their PBMC. Therefore, true clearance of HCV infection is difficult to achieve in these patients.
Exclusion of mosaicism in Spanish haemophilia A families with inversion of intron 22
Authors: Tizzano E. F. , Cornet M. , Domènech M. , Baiget M.
Published: September 2003

Summary.  Inversion of intron 22, the most frequent mutation event in haemophilia A (HA), was tested in our HA families to diagnose the females at risk of being carriers, to trace the origin of the mutation and to investigate the presence of germinal or somatic mosaicism. A total of 166 females belonging to 54 families with inversion, were analysed. All but one of the mothers tested were carriers and the inversion originated almost exclusively in male germ cells. Somatic or germline mosaicisms were excluded in 53 of these women and in 20 grandfathers, suggesting that such mosaicisms may be a rare event in families with inversion of intron 22.
Immunization of patients with bleeding disorders
Authors: Makris M. , Conlon C. P. , Watson H. G.
Published: September 2003

Summary.  The immunization of patients with bleeding disorders differs from that of the normal population with respect to the risk of haematoma formation at the vaccination site and the unusual infective risks assiciated with the potential, and past, exposure to blood products. Most vaccinations can be given subcutaneously and this should be the preferred route. All routine childhood vaccinations should be given at the appropriate time. All patients with bleeding disorders should be vaccinated against hepatitis A and B. HIV positive patients should receive annual influenza vaccinations and should avoid the oral polio, oral typhoid, BCG and yellow fever vaccines.
Solubility of root‐canal sealers in water and artificial saliva
Authors: Schäfer E. , Zandbiglari T.
Published: September 2003

Aim  To compare the weight loss of eight different root‐canal sealers in water and in artificial saliva with different pH values.

Methodology  For standardized samples (n = 12 per group), ring moulds were filled with epoxy resin (AH 26, AH Plus)‐, silicone (RSA RoekoSeal)‐, calcium hydroxide (Apexit, Sealapex)‐, zinc oxide–eugenol (Aptal‐Harz)‐, glass‐ionomer (Ketac Endo)‐ and polyketone (Diaket)‐based sealers. These samples were immersed in double‐distilled water or artificial saliva with different pH values (7.0, 5.7 and 4.5) for 30 s, 1 min, 2 min, 5 min, 10 min, 20 min, 1 h, 2 h, 10 h, 24 h, 48 h, 72 h, 14 days and 28 days. Mean loss of weight was determined and analysed statistically using a one‐way anova and Student–Newman–Keuls test for all pairwise comparisons.

Results  Most sealers were of low solubility, although Sealapex, Aptal‐Harz and Ketac Endo showed a marked weight loss in all liquids. Even after 28 days of storage in water, AH 26, AH Plus, RSA RoekoSeal, and Diaket showed less than 3% weight loss. At exposure times greater than 14 days, Sealapex showed the significantly greatest weight loss of all sealers tested (P < 0.05). Aptal‐Harz and Ketac Endo were significantly more soluble in saliva (pH 4.5) than in water (P < 0.05).

Conclusions  Under the conditions of the present study, AH Plus showed the least weight loss of all sealers tested, independent of the solubility medium used. Sealapex, Aptal‐Harz and Ketac Endo had a marked weight loss in all liquids.
Removal of gutta‐percha from root canals using an Nd:YAG laser
Authors: Vidučić D. , Jukić S. , Karlović Z. , Božić Ž. , Miletić I. , Anić I.
Published: September 2003

Aim  To examine the use of an Nd:YAG laser in removing gutta‐percha fillings from root canals when used in conjunction with eucalyptol, dimethylformamide (DMF) or no solvent.

Methodology  Root‐canal fillings (sealer and gutta‐percha) were removed with laser irradiation of 20 Hz/1.5 W from 30 roots randomly divided in three groups. In group 1, the solvent was eucalyptol; in group 2, the solvent was DMF; and in group 3, no solvent was used. Laser irradiation was performed until the temperature measured on the root surface increased by 4 °C over room temperature. The treatment was deemed complete when the apical foramen was reached with the optical fibre and a reamer. The samples were split longitudinally, and the area of remaining gutta‐percha on the root‐canal walls was determined with the aid of a computer program. The total number of laser pulses to achieve length and the highest temperature recorded was determined for each tooth. The results were statistically analysed using Student's t‐test (P < 0.05) for independent samples.

Results  The average temperature increase in group 1 was 9.17 ± 0.56 °C; in group 2, 9.56 ± 0.28 °C; and in group 3, 8.29 ± 0.41 °C. The shortest time to achieve length was in group 3 (6.4 ± 0.49 min), then in group 1 (6.7 ± 0.85 min) and group 2 (7.05 ± 0.79 min). The area of remaining gutta‐percha was the largest in group 2 (6.13 ± 5.76%), whilst the smallest was for group 3 (4.69 ± 4.03%), but the difference was not statistically significant. The number of pulses was not statistically significant between the groups.

Conclusions  Use of an Nd:YAG laser alone is capable of softening gutta‐percha. The addition of solvents did not improve the retreatment, either in terms of the time required for the procedure or in terms of the area of remaining gutta‐percha on root‐canal walls.
A combined radiographic and computerized scanning method to evaluate remaining dentine thickness in mandibular incisors after various intracanal procedures
Authors: Katz A. , Tamse A.
Published: September 2003

Aim  To develop a computerized model to evaluate remaining dentine thickness after various intracanal procedures.

Methodology  A three‐step model was developed, in which injection of radiopaque solution into the root‐canal space of 20 extracted mandibular incisors, exposure of periapical radiographs from two directions, and computerized scanning and printing of the image were combined. Following root‐canal preparation and preparation of post space, evaluation of remaining dentine thickness was completed using appropriate software.

Results  Remaining dentine thickness was significantly affected (P < 0.01) by place (mesial–distal more than buccal–lingual), stage (root‐canal preparation more than post space) and location (coronal more than middle and apical).

Conclusions  This in vitro study confirmed that in an oval root‐canal space, the mesial and distal aspects are mainly affected by intraradicular procedures. The three‐step method is a useful tool to evaluate root‐canal instrumentation as the root or tooth can remain intact during the procedure.
Factors influencing the removal of posts
Authors: Hauman C. H. J. , Chandler N. P. , Purton D. G.
Published: September 2003

Aim  To determine whether metal type, cement type and the use of ultrasonic vibration influence the amount of tensile force required to remove parallel‐sided, prefabricated, metal posts from tooth roots.

Methodology  Ninety extracted canine teeth were sectioned horizontally 1‐mm coronal to the labial cemento–enamel junction and embedded in acrylic blocks. Standardized post spaces were prepared with a ParaPost no. 5 (1.25 mm) drill to 10 mm and ParaPost XP no. 5 stainless steel and titanium posts were cemented using zinc phosphate, glass ionomer or composite resin cement. Sixty posts were subjected to 16 min of ultrasonic vibration whilst 30 stainless steel posts received no vibration. The force required for post removal was determined using a universal testing machine. Results were analysed using univariate anova.

Results  The univariate anova revealed no statistically significant differences between the groups at the P = 0.05 level.

Conclusions  In this in vitro experiment, metal type, cement type and ultrasonic vibration did not influence the force required to remove posts.
How important is climate? Effects of warming, nutrient addition and fish on phytoplankton in shallow lake microcosms
Authors: Moss Brian , Mckee D. , Atkinson D. , Collings S. E. , Eaton J. W. , Gill A. B. , Harvey I. , Hatton K. , Heyes T. , Wilson D.
Published: September 2003

Climate is changing. Predictions are for at least a 3 °C rise in mean temperature in northern Europe over the next century. Existing severe impacts of nutrients and inappropriate fish stocking in freshwater systems remain.

Effects of warming by 3 °C above ambient, nutrient addition and the presence or absence of sticklebacks Gasterosteus aculeatus were studied in experimental microcosms dominated by submerged plants, mimicking shallow lake ecosystems.

Warming had considerably smaller effects on the phytoplankton community than did fish and nutrients. It had very minor effects on chlorophyll a and total phytoplankton biovolume. However, it significantly decreased the biovolumes of Cryptophyceae (a major component in the controls) and Dinophyceae. Contrary to expectation, warming did not increase the abundance of blue‐green algae (cyanophytes). Warming decreased the abundances of Cryptomonas erosa (Cryptophyceae) and Oocystis pusilla (Chlorophycota) and increased those of two other green algae, Tetraedron minimum and Micractinium pusillum. It had no effect on a further 17 species that were predominant in a community of about 90 species.

Fish and nutrients, either together or separately, generally increased the crops of most of the 21 abundant species and of the algal groups. Exceptions were for diatoms and chrysophytes, which were very minor components of the communities. Fish, but neither nutrients nor warming, increased the number of species of phytoplankton detected. This was probably through removal of zooplankton grazers, and parallels terrestrial studies where the presence of top predators, by controlling herbivores, leads to increased plant diversity.

There was no particular pattern in the taxonomy or biological characteristics of those species affected by the treatments. In particular, there was no link between organism size (a surrogate for many important biological features of phytoplankton species) and the effects of warming, nutrient addition or presence or absence of fish. However, all species were relatively small and potentially vulnerable to grazing.

Synthesis and applications. The results suggest that fears of an increasing abundance of cyanophytes with current projections of global warming may be unrealized, at least in shallow unstratified lakes still dominated by macrophytes. However, they emphasize that eutrophication and fish manipulations remain very important impact factors that determine the abundance of phytoplankton and subsequent problems caused by large growths.
Demographic models and the management of endangered species: a case study of the critically endangered Seychelles magpie robin
Authors: Norris Ken , Mcculloch Neil
Published: September 2003

Demographic models are assuming an important role in management decisions for endangered species. Elasticity analysis and scope for management analysis are two such applications. Elasticity analysis determines the vital rates that have the greatest impact on population growth. Scope for management analysis examines the effects that feasible management might have on vital rates and population growth. Both methods target management in an attempt to maximize population growth.

The Seychelles magpie robinCopsychus sechellarumis a critically endangered island endemic, the population of which underwent significant growth in the early 1990s following the implementation of a recovery programme. We examined how the formal use of elasticity and scope for management analyses might have shaped management in the recovery programme, and assessed their effectiveness by comparison with the actual population growth achieved.

The magpie robin population doubled from about 25 birds in 1990 to more than 50 by 1995. A simple two‐stage demographic model showed that this growth was driven primarily by a significant increase in the annual survival probability of first‐year birds and an increase in the birth rate. Neither the annual survival probability of adults nor the probability of a female breeding at age 1 changed significantly over time.

Elasticity analysis showed that the annual survival probability of adults had the greatest impact on population growth. There was some scope to use management to increase survival, but because survival rates were already high (> 0·9) this had a negligible effect on population growth. Scope for management analysis showed that significant population growth could have been achieved by targeting management measures at the birth rate and survival probability of first‐year birds, although predicted growth rates were lower than those achieved by the recovery programme when all management measures were in place (i.e. 1992–95).

Synthesis and applications.We argue that scope for management analysis can provide a useful basis for management but will inevitably be limited to some extent by a lack of data, as our study shows. This means that identifying perceived ecological problems and designing management to alleviate them must be an important component of endangered species management. The corollary of this is that it will not be possible or wise to consider only management options for which there is a demonstrable ecological benefit. Given these constraints, we see little role for elasticity analysis because, when data are available, a scope for management analysis will always be of greater practical value and, when data are lacking, precautionary management demands that as many perceived ecological problems as possible are tackled.
Monitoring salt stress in grapevines: are measures of plant trait variability useful?
Authors: Sinclair Chantelle , Hoffmann Ary A.
Published: September 2003

Measures of trait variability, in particular fluctuating asymmetry (FA), have been proposed as biological tools for monitoring environmental quality, but relevant data are often collected under artificial conditions and it can be difficult to separate genetic and environmental factors. We considered a number of trait variability measures for potential use as indicators in field grapevines exposed to salt stress.

Vine responses to a salt gradient were compared using two measures of developmental stability (DS). DS quantifies an organisms’ ability to buffer developmental noise. The two measures of DS tested were leaf FA, representing random deviations from perfect bilateral symmetry, and translational asymmetry (TA), representing deviations in allometric relationships, in this case the relationship between internode distance and node order. Leaf size (measured as centroid size), leaf shape (calculated using the Procrustes method) and maximum internode length were also tested for sensitivity to salinity.

We found that both measures of DS, FA and TA, failed to identify salinity stress in grapevines. Other measures, such as maximum internode length, leaf shape and leaf size, were sensitive to salt stress.

Synthesis and applications. Often, salinity stress is detected only when the impact is harmful enough to cause severe biological effects. Alternative, more sensitive monitoring techniques would allow earlier intervention and management of the problem. We evaluated a number of techniques and showed that indices of bilateral and TA were not useful in detecting salt stress in grapevines. However, changes in internode length, leaf size and leaf shape proved to be sensitive and are potential tools for monitoring salinity in vineyards.
Aerial activity of linyphiid spiders: modelling dispersal distances from meteorology and behaviour
Authors: Thomas C. F. G. , Brain P. , Jepson P. C.
Published: September 2003

Dispersal parameters are critical for modelling spatially dynamic populations yet remain among the most difficult to quantify. Linyphiid spider aerial dispersal by ‘ballooning’ on silk threads is dependent on meteorological factors and amenable to analysis and quantification.

Spider aerial activity was measured during consecutive 10‐min periods for up to 11 h a day. Aerial density was measured at four heights using sticky traps. The time intervals between successive flights were measured by observing spiders landing and taking‐off.

Meteorological measurements (wind speeds and temperatures) were taken simultaneously with the collection of airborne spiders, and used to calculate Richardson numbers to estimate atmospheric turbulence.

Numbers of airborne spiders on any given day, and their vertical density profile on different days, were significantly correlated with Richardson numbers.

Single flight distances were modelled using estimates of ascent and descent rates, the vertical density profile of airborne spiders and the wind speeds they experience aloft. The distributions of single flight distances and the time spent between successive flights were combined in an alternating renewal process to model the number of flights and the total daily dispersal distances of ballooning spiders as a function of available dispersal time.

On a day with, for example, 6 h of suitable weather, linyphiid spiders can potentially disperse a mean distance of approximately 30 km downwind.

Synthesis and applications. We have developed a dispersal model of linyphiid spiders that is central to the further development of spatially dynamic population models of these spiders in agricultural landscapes. It could also be adapted for application to other wind‐borne organisms. Such models have a key role in the future management of sustainable agricultural systems where natural predators are seen as major components of pest control.
Soil ammonium accumulation after sod cutting hampers the restoration of degraded wet heathlands
Authors: Dorland E. , Bobbink R. , Messelink J. H. , Verhoeven J. T. A.
Published: September 2003

Restoration of formerly species‐rich wet heaths and matgrass swards has not always been successful. The constraints on this restoration process are not yet fully understood and need further investigation, particularly the accumulation of ammonium in the soil after sod cutting, i.e. the removal of the vegetation and topsoil layer. This accumulation is known from sod cutting experiments in dry heaths, but had not previously been studied in wet heaths and matgrass ecosystems.

In 2000, sods were cut from two degraded Dutch wet heaths. Soil chemistry and germination in the sod‐cut plots were measured at irregular intervals between April 2000 and August 2001. To test the influence of ammonium on germination and survival, a glasshouse dose–response experiment was conducted with two endangered wet heath plant species.

In both wet heaths, an accumulation of KCl‐extractable ammonium up to 600 µmol kg−1 dry soil was found in the upper 10 cm of the soil within the first year after sod cutting. These high ammonium concentrations lasted for about 10 months. Germination was very low in the sod‐cut plots in 2000 and 2001, and few target species were found, although they were present in the vicinity.

The dose–response experiment indicated a significant, negative correlation of both germination and survival with increasing ammonium addition for both plant species. Mean soil ammonium concentrations of the control, 100 and 250 µm ammonium treatments were significantly lower than those of the 500 and 1000 µm ammonium treatments (47, 45, 70, 144 and 252 µmol kg−1 dry soil, respectively).

Maximum concentrations of KCl‐extractable ammonium in the field corresponded to water‐extractable concentrations that were higher than those found to be limiting germination and growth in the glasshouse experiments. The low germination in the field is likely to have been adversely affected by high concentrations of ammonium as a result of sod cutting.

Synthesis and applications. High ammonium concentrations occur in wet heaths following sod cutting. Low rates of germination of restoration target plant species occur under such conditions. To increase the success of wet heath restoration, the accumulation of ammonium after sod cutting should be prevented by additional measures, such as liming. Because sod cutting is also applied as a restoration measure in the restoration of other ecosystems, such as fens, the effects on increased soil ammonium concentrations need further attention.
Indirect effects of grazing and nutrient addition on the hemipteran community of heather moorlands
Authors: Hartley S. E. , Gardner S. M. , Mitchell R. J.
Published: September 2003

Moorlands dominated by heather Calluna vulgaris are of international conservation importance, but are declining as a result of increased grazing pressure and deposition of atmospheric pollutants. Grazing and nutrient deposition can alter the composition, structure and nutritional quality of the vegetation, which may affect the diversity of herbivorous insects. However, the drivers of insect community diversity in moorlands remain poorly understood.

Here we quantify the changes in moorland vegetation caused by grazing and nutrient addition, together with the effects of these changes on the community structure of a major group of herbivorous insects on moorlands, the Hemiptera. Fencing and fertilizer treatments were used to test the hypotheses that: (1) hemipteran species richness is related to plant species richness; (2) fertilizer addition increases host plant quality and hence the abundance and diversity of Hemiptera; and (3) a reduction in grazing alters vegetation structure and hence the composition of the hemipteran community.

Sites with more mineral soils had the most plant species and the largest species richness and abundance of Hemiptera, supporting hypothesis 1. Fertilizer increased the nitrogen content of both grasses and Calluna and significantly increased Hemiptera abundance and species richness (hypothesis 2), although the effect of fertilizer on diversity was smaller than that of site‐based factors such as plant species richness.

Grazing altered vegetation structure (hypothesis 3): fenced plots increased Calluna ground cover, height and canopy occupancy but reduced grass cover. Four months after the fencing and fertilizer treatments, the level of grazing on Calluna was the prime factor influencing the composition of the hemipteran community. However, after 2 years of the treatments, soil organic content and prevalence of Nardus and new‐growth Calluna had become the greatest influence on community composition.

Synthesis and applications. Grazing and nitrogen deposition alter the vegetation of moorland landscapes and this study shows that these factors also have significant effects on the abundance, species richness and species composition of moorland invertebrates. However, site‐based factors such as soil organic content and plant species richness had the greatest impact on the hemipteran community because plant diversity appears to be the most important driver of hemipteran diversity. Moorland managers may be able to maximize hemipteran species richness using a grazing regime that maintains a mosaic of dwarf shrub and grass cover. Site‐specific factors such as soil type need to be considered when managing moorlands for conservation.
Microsite availability and establishment of native species on degraded and reclaimed sites
Authors: Elmarsdottir Asrun , Aradottir Asa L. , Trlica M. J.
Published: September 2003

Restoration of native plant communities on previously disturbed land requires the identification and modification of environmental factors that impede or restrict ecosystem succession or development. One of the key factors in successful reclamation is to ensure colonization and persistence of native species within an area. Therefore, the identification of microsite types that favour colonization by native species should improve our ability to successfully reclaim degraded areas.

The objectives of this study were to (i) identify and describe microsite types that were conducive to the establishment of five native plant species (Euphrasia frigida, Galium normanii, Thymus praecox, Cerastium spp. and Rumex acetosa) on degraded and reclaimed sites in Iceland; and (ii) to determine the effects of reclamation activities that included the application of manure and inorganic fertilizer on the distribution of microsite types and seedling establishment. Reclamation sites of different ages were examined on an eroded area where the target community was a grass or shrub heath.

The spatial distribution of plant establishment was not random but varied among microsite types and study sites. More seedlings than expected were found in microsite types characterized by small rocks and biological soil crusts. These may have entrapped seed and provided more soil stability and moisture than other microsite types. The cover of these microsite types varied among the study sites but the pattern of seedling establishment among the five native forbs was similar.

Synthesis and applications. Practical reclamation methods are improved by identifying those factors that promote successful seedling establishment by native species. Application of fertilizer without additional seeding proved to be a simple reclamation approach that increased the availability of one favourable microsite type, enhanced the establishment of native species and subsequently allowed vegetation cover to expand. Seed of native plants may be difficult to obtain commercially, but this approach can be used on degraded land where propagules are available but recovery is slowed by soil instability or nutrient limitations.
The effect of density‐dependent catastrophes on population persistence time
Authors: Wilcox Chris , Elderd Bret
Published: September 2003

There has been increasing recognition that catastrophes are an important factor in modelling threatened populations. However, density dependence has generally been omitted from models of threatened populations on the assumption that this omission yields conservative predictions. We explore the significance of including density‐dependent catastrophes in models of threatened populations.

Using an analytical model, we show that density‐dependent catastrophes have a significant effect on population persistence, decreasing mean persistence time at large population sizes and causing a relative increase at intermediate sizes.

We illustrate our results with empirical data from a disease outbreak in crabeater seals Lobodon carcinophagus and show that intermediate population sizes have the longest predicted persistence times.

The pattern we found is qualitatively different from previous results on persistence time based on density‐independent models, in which persistence time increases with population size to an asymptote.

Synthesis and applications. This study has important implications for the conservation of species that may experience density‐dependent catastrophes, such as disease outbreaks or starvation. Our results indicate that small and intermediate sized populations may contribute disproportionately to species persistence. Thus populations that have been dismissed as ‘marginal’ may actually be important for conservation. In addition, culling may increase the persistence of populations that experience density‐dependent catastrophes.
Landscape patterns of indicator plants for soil acidity in the Bavarian Alps
Authors: Schmidtlein Sebastian , Ewald Jörg
Published: September 2003

Aim  Electronic distribution atlases and lists of ecological indicator values are becoming important tools in plant geography. In this contribution, we combine a geographical and an ecological data bank, and map out patterns of indicator value spectra (instead of single or average values) across a physiographically complex landscape. For our study, we select indicators of soil pH and carbonate content as key environmental factors that strongly affect overall plant diversity patterns in the temperate zone. Our goal is to relate the distribution and diversity of plant groups that are indicators of soil pH and carbonate content to environmental controls at the landscape‐scale, and thus contribute to a causal understanding of species pools.

Location  We studied the Bavarian Alps, which represent the German portion of the Northern Alps.

Methods  Based on the existing floristic survey, we calculated relative frequencies of nine classes of indicator plants for soil pH and carbonate content in grid cells. The resulting attribute matrix (cells by indicator class frequencies) was subjected to principal components analysis and to k‐means clustering. Results were compared and mapped out in the grid array of the whole region, resulting in continuous and discrete representations of species pool structure. We used a geographical information system to derive physiographical landscape properties from a geological map and a digital elevation model, and analysed their statistical relationship with the shapes of indicator spectra.

Results and Main conclusions  Averages of indicator values for soil pH and carbonate content follow the geological structure quite closely. Surprisingly, the diversity of indicator plant groups does not appear to be a function of geological or topographic heterogeneity. Rather, it seems to be related to areas of high elevation with uniform geology. The effect is a matter of additional acidophytes in high mountain areas and, in the high calcareous Alps, extreme calciphytes, while species with intermediate requirements are rarer than usual. For explanation, we suggest two facts: (1) a frequent lack of mature soils at high elevations and (2) particularities in soil genetic processes occurring under the harsh climatic conditions of high mountains.
Small island biogeography in the Gulf of California: lizards, the subsidized island biogeography hypothesis, and the small island effect
Authors: Barrett K. , Wait D. A. , Anderson W. B.
Published: September 2003

Aim We used insular lizard communities to test the predictions of two hypotheses that attempt to explain patterns of species richness on small islands. We first address the subsidized island biogeography (SIB) hypothesis, which predicts that spatial subsidies may cause insular species richness to deviate from species–area predictions, especially on small islands. Next, we examine the small island effect (SIE), which suggests small islands may not fit the traditional log‐linear species–area curve.

Location Islands with arthropodivorous lizard communities throughout the Gulf of California.

Methods To evaluate the SIB hypothesis, we first identified subsidized and unsubsidized islands based on surrogate measures of allochthonous productivity (i.e. island size and bird presence). Subsequently, we created species–area curves from previously published lizard species richness and island area data. We used the residuals and slopes from these analyses to compare species richness on subsidized and unsubsidized islands. To test for an SIE, we used breakpoint regression to model the relationship between lizard species richness and island area. We compared results from this model to results from the log‐linear regression model.

Results Subsidized islands had a lower slope than unsubsidized islands, and the difference between these groups was significant when small islands were defined as < 1 km2. In addition to comparing slopes, we tested for differences in the magnitude of the residuals (from the species–area regression of all islands) for subsidized vs. unsubsidized islands. We found no significant patterns in the residual values for small vs. large islands, or between islands with and without seabirds. The SIE was found to be a slightly better predictor of lizard species richness than the traditional log‐linear model.

Main conclusions Predictions of the SIB hypothesis were partially supported by the data. The absence of a significant SIE may be a result of spatial subsidies as explained by the SIB hypothesis and data presented here. We conclude by suggesting potential scenarios to test for interactions between these two small island hypotheses. Future studies considering factors affecting species richness should examine the possible role of spatial subsidies, an SIE, or a synergistic effect of the two in data sets with small islands.
Dispersal and diversification: macroevolutionary implications of the MacArthur–Wilson model, illustrated by Simulium (Inseliellum) Rubstov (Diptera: Simuliidae)
Authors: Spironello Mike , Brooks Daniel R.
Published: September 2003

Aim Provide an empirical test of the ‘radiation zone’ hypothesis of the MacArthur–Wilson theory of island biogeography using the taxon‐pulse hypothesis of Erwin and Brooks Parsimony Analysis (BPA) on Simulium (Inseliellum) Rubstov.

Location Micronesia, Cook Islands, Austral Islands, Society Islands, Marquesas Islands, Fiji and New Caledonia.

Methods Primary and secondary BPA of the phylogeny of Inseliellum.

Results Primary BPA showed that 15% of the taxon area cladogram contained area reticulations. Secondary BPA (invoking the area duplication convention) generated a clear sequence of dispersal for Inseliellum. The sequence follows a Micronesia – Cook Islands – Marquesas Islands – Society Islands dispersal, with a separate dispersal from the Cook Islands to the Austral Islands less than 1 Ma. A radiation in the island of Tahiti (Society Islands) produced numerous dispersals from Tahiti to other islands within the Society Islands system. Islands close to Tahiti (source island) have been colonized from Tahiti more often than islands far from Tahiti, but a higher proportion of those species colonizing distant islands have become distinct species.

Main conclusions The dispersal sequence of Inseliellum exhibits both old to young island dispersal and young to old island dispersal. This is due to habitat availability on each island. Inseliellum is a model system in exemplifying the ‘radiation zone’ hypothesis of MacArthur and Wilson. As well, islands close to the source are colonized more often that those far from the source, but colonization of islands far away from the source results in a higher proportion of speciation events than for islands close to the source. The diversification of Inseliellum corresponds to a taxon‐pulse radiation, with a centre of diversification on Tahiti resulting from its large area and abundant freshwater habitats. This study illustrates the utility of BPA in identifying complex scenarios that can be used to test theories about the complementary roles of ecology and phylogeny in historical biogeography.
Seasonal distribution of a migratory bird: effects of local and regional resource tracking
Authors: Tellería José Luis , Pérez‐Tris Javier
Published: September 2003

AimWe studied how local and regional abundance of a migratory passerine (the blackcapSylvia atricapilla) track resource availability in breeding and wintering grounds, in an attempt to understand the processes underlying the distribution and regulation of migratory bird populations in summer and in winter.

LocationOur study was conducted in Spain. In summer, we sampled five localities representing the diversity of environmental conditions met by breeding Spanish blackcaps. In winter, we sampled eight localities in the wintering range of the species including different habitat types (forests and shrublands).

MethodsOur approach was based on the matching rule, a model that predicts that any local variation in resource abundance between two adjacent habitat patches should be tracked by animals through a similar variation in population abundance. Eventually, this local process should conform to abundance distributions at regional scales. We sampled two habitat patches in each locality, each one including three to five line transects, 500‐m long and 50‐m wide, where we counted blackcaps and measured vegetation structure and fruit abundance.

ResultsDuring the breeding season, the abundance of blackcaps was strongly correlated with the ground cover of brambles (Rubusspp.), a bush which grows in moist sectors in Mediterranean forests and is the commonest nesting substrate of Spanish blackcaps. Both local and regional changes in bramble cover were tracked by variations in blackcap abundance. However, the rate of increase in blackcap abundance with increasing bramble cover along the Spanish gradient was lower than the one predicted under resource matching. In winter, abundance of fruiting shrubs was the best predictor of blackcap abundance, although local abundance of blackcaps not always fitted local abundance of fruits. Notwithstanding this effect, the regional pattern of abundance tracked changes in fruit availability according to the matching rule.

Main conclusionsOur results support the strong effect of habitat quality on the abundance distribution of blackcaps and the tracking of different key resources along the year. Together with the different degrees of resource tracking by blackcaps at local and regional scales, these results also support the view that both breeding and wintering processes have to be studied, and studies have to be conducted at the appropriate spatial scales, if we are to understand the processes underlying the abundance distribution of migratory birds.
A floristic analysis of the lowland dipterocarp forests of Borneo
Authors: Slik J. W. F. , Poulsen A. D. , Ashton P. S. , Cannon C. H. , Eichhorn K. A. O. , Kartawinata K. , Lanniari I. , Nagamasu H. , Nakagawa M. , Van Nieuwstadt M. G. L. , Payne J. , Purwaningsih  , Saridan A. , Sidiyasa K. , Verburg R. W. , Webb C. O. , Wilkie P.
Published: September 2003

Aim To (1) identify floristic regions in the lowland (below 500 m a.s.l.) tropical dipterocarp rain forest of Borneo based on tree genera, (2) determine the characteristic taxa of these regions, (3) study tree diversity patterns within Borneo, and (4) relate the floristic and diversity patterns to abiotic factors such as mean annual rainfall and geographical distance between plots.

Location Lowland tropical dipterocarp rain forest of Borneo.

Methods We used tree (diameter at breast height ≥ 9.8 cm) inventory data from 28 lowland dipterocarp rain forest locations throughout Borneo. From each location six samples of 640 individuals were drawn randomly. With these data we calculated a Sørensen and Steinhaus similarity matrix for the locations. These matrices were then used in an UPGMA clustering algorithm to determine the floristic relations between the locations (dendrogram). Principal coordinate analysis was used to ordinate the locations. Characteristic taxa for the identified floristic clusters were determined with the use of the INDVAL method of Dufrene & Legendre (1997). Finally, Mantel analysis was applied to determine the influence of mean annual rainfall and geographical distance between plots on floristic composition.

Results A total of 77 families and 363 genera were included in the analysis. On average a random sample of 640 trees from a lowland dipterocarp forest in Borneo contains 41.6 ± 3.8 families and 103.0 ± 12.7 genera. Diversity varied strongly on local scales. On a regional scale, diversity was found to be highest in south‐east Borneo and central Sarawak. The most common families were Dipterocarpaceae (21.9% of trees) and Euphorbiaceae (12.2% of trees). The most common genera were Shorea (12.3% of trees) and Syzygium (5.0% of trees). The 28 locations were clustered in geographically distinct floristic regions. This was related to the fact that floristic similarity depended strongly on the geographical distance between plots and similarity in mean annual rainfall.

Conclusions We identified five main floristic regions within the lowland dipterocarp rain forests of Borneo, each of which had its own set of characteristic genera. Mean annual rainfall is an important factor in explaining differences in floristic composition between locations. The influence of geographical distance on floristic similarity between locations is probably related to the fact that abiotic factors change with distance between plots. Borneo's central mountain range generally forms an effective dispersal barrier for the lowland tree flora. Diversity patterns in Borneo are influenced by the mid‐domain effect, habitat size and the influence of past climatic changes (ice ages during the Pleistocene).
Detection of gastric slow wave uncoupling from multi‐channel electrogastrogram: validations and applications
Authors: Wang Z. S. , Elsenbruch S. , Orr W. C. , Chen J. D. Z.
Published: September 2003

Current methodology of single channel electrogastrography is unable to detect coupling or uncoupling of gastric slow waves, which is crucial for gastric emptying. In this study, a new methodology, called cross‐spectral analysis method, was established to compute the coupling percentage of multi‐channel gastric slow waves recorded using serosal electrodes and electrogastrogram (EGG). Two experiments were performed to validate the method and demonstrate its applications in clinical research. In experiment 1, simultaneous recordings of gastric slow waves were made in five dogs from serosal electrodes and cutaneous electrodes. In experiment 2, four‐channel fasting EGGs were made in 10 volunteers for 30 min during waking and 30 min during non‐rapid eye movement (REM) sleep. The validation study (experiment 1) showed that the slow wave coupling calculated from the EGGs was correlated with that computed from the serosal recordings. The gastric slow wave coupling percentages detected from both serosal and cutaneous recordings were significantly impaired during vasopressin infusion (6.3 ± 2.6 vs 62.4 ± 6.3, P < 0.001 for serosal recordings; 6.7 ± 3.0 vs 57.2 ± 2.7, P < 0.001 for cutaneous recordings), and the coupling percentages respectively calculated from serosal and cutaneous recordings were significantly correlated during the baseline recording period (R = 0.922, P < 0.05) and vasopressin infusion period (R = 0.916, P < 0.05). In experiment 2, the gastric slow wave became less coupled when healthy volunteers fell asleep. The percentage of slow wave coupling calculated from the EGGs was 68.2 ± 17.9% during waking but 41.9 ± 20.8 during non‐REM sleep (P < 0.05). The method developed in this study is reliable for the detection of slow wave uncoupling from multi‐channel EGGs. Gastric slow wave coupling is impaired during vasopressin infusion and sleep. These data suggest that this method has potential applications in physiological and clinical studies.
Biomagnetic detection of gastric electrical activity in normal and vagotomized rabbits
Authors: Bradshaw L. A. , Myers A. G. , Redmond A. , Wikswo J. P. , Richards W. O.
Published: September 2003

We recorded the vector magnetogastrogram (MGG) due to gastric electrical activity (GEA) in normal rabbits using a Superconducting QUantum Interference Device (SQUID) magnetometer and measured the degree of correlation of the MGG with 24 channels of serosal electrodes. The vector magnetometer allows us to non‐invasively record three orthogonal magnetic field components and project the recorded magnetic field vector into arbitrary directions. We optimized the magnetic field vector direction to obtain the highest possible correlation with each serosal electrode recording. We performed a vagotomy and examined spatial and temporal changes in the serosal potential and in the transabdominal magnetic field. We obtained spatial information by mapping the recorded signals to the electrode positions in the gastric musculature. Temporal evidence of uncoupling was observed in spectral analyses of both serosal electrode and SQUID magnetometer recordings. We conclude that non‐invasive recordings of the vector magnetogastrogram reflect underlying serosal potentials as well as pathophysiological changes following vagotomy.