bluuebunny/crossref_metadata_2025 huggingface dataset:
Shear Modulus and Yield Stress Measurements of Attractive Alumina Particle Networks in Aqueous Slurries
Authors: Yanez Joseph A. , Shikata Toshi , Lange Fred F. , Pearson Dale S.
Published: September 2005

The shear modulus and yield stress of attractive alumina particle networks in aqueous slurries was determined as a function of volume fraction (0.1 to 0.5), pH (2, 4, 5, 6, and 9), and salt (NH4l) concentration (0.25M to 2.34) using both vane and couette rheological tools. Consistent with previous observations concerning the relative strength of attractive particle networks, the shear modulus increased to a plateau value with salt concentration. In this work we have shown that the salt concentration at which this plateau value is achieved is a function of the pH, and thus, the surface charge density. The values of the shear modulus [G′], yield stress [τy], and yield strain [γy] of the attractive networks can be described with power law functions for particle volume fraction [φ] (G′∝φ4.75, τy∝φ3.6, and γy∝φ−1.1) and salt concentration [c] (G′∝ [c]2.0, τ, ∝ [c]1.15, and γy∝ [c]−0.85).
Thermoelastic Behavior in Ca2SiO4 Solid Solutions
Authors: Fukuda Koichiro , Maki Iwao , Ito Suketoshi
Published: September 2005

Dicalcium silicate solid solutions (C2S(ss)) doped with Na2O, A12O3, and Fe2O3 were examined by high‐temperature optical microscopy. Surface deformation caused by a possible martensitic transformation between a′L and β phases was observed in situ under the microscope during temperature changes, indicating that the transformation was thermoelastic. Both the start and finish temperatures of the a′L‐to‐β and β‐to‐a′L transformations decreased with increased Na:(Na + Ca) ratio. Because of the athermal nature of the a′L‐to‐β transformation, the a′L phase, when cooled below the finish temperature, should have been completely converted to the β phase.
Ultrafine Alumina Particles Prepared by Mechanochemical/Thermal Processing
Authors: Ding Jun , Tsuzuki Takuya , McCormick Paul G.
Published: September 2005

Ultrafine alumina particles have been prepared by the mechanical milling and subsequent heat treatment of a mixture of AICI3 and CaO. Heat treatment of the as‐milled powder at temperatures above 350°C and washing with water resulted in γ‐Al2O3 particles 10–20 nm in size. Single phase α‐Al2O3 was formed in the sample after heat treatment at 1250°C. This study demonstrates a novel process for synthesizing nanoscale alumina particles.
Thermal Hysteresis for the α′L↫β Transformations in Strontium Oxide‐Doped Dicalcium Silicates
Authors: Fukuda Koichiro , Maki Iwao , Ito Suketoshi
Published: September 2005

A series of Sr‐bearing Ca2SiO4 solid solutions (C2S(ss)), (SrxCa1−x)2SiO4 with 0 ≤x≤ 0.12, was prepared. They were examined by high‐temperature powder X‐ray diffractome‐try to determine the start and finish temperatures of the α′L‐to‐β and β‐to‐α′L martensitic transformations. The thermal hysteresis was positive with x< 0.045, nearly equal to zero at x= 0.045, and negative with x > 0.045. The zero and negative hysteresis were consistent with the thermoelasticity of the transformations. With increasing x from 0.02 to 0.08, the hysteresis decreased steadily from positive to negative, suggesting a continuous increment in the stored elastic energy.
Superoxidation and Electrochemical Reactions during Switching in Pb(Zr2Ti)O3 Ceramics
Authors: Pan Ming‐Jen , Park Seung‐Eek , Park Colin W. , Markowski Kelley A. , Yoshikawa Shoko , Randall Clive A.
Published: September 2005

Under ferroelectric switching in Pb(Zr2Ti)O3 (PZT) ceramics, we demonstrate that oxygen gas is emitted and degrades electrode microstructure. The oxygen is a direct result of the defect chemistry associated with superoxidation which is established during the processing of the ceramics. Under high alternating electric fields, electron injection into the ceramic surface induces a reduction process, and surface layers are believed to change from a p‐type electronic compensation to an ionic compensation of oxygen vacancies and A‐site lead vacancies. During this process, we noticed progressive changes in capacitance, loss, remnant polarization, and coercive field. The wider implications of this observation for PZT thin film nonvolatile memories are discussed in brief.
Atomistic Structure of Silicon Nitride/Silicate Glass Interfaces
Authors: Pan Xiaoqing
Published: September 2005

The structure of interfaces formed by a Si3N4 grain and the silica‐rich intergranular amorphous phase was investigated by quantitative high‐resolution transmission electron microscopy (QHRTEM). It was found that the contrast and periodicity of the HRTEM image of β‐Si3N4 strongly depend on the specimen thickness and objective lens focus value. The different thinning rate between Si3N4 and the glass phase during ion‐milling results in gradients of the specimen thickness at the interfaces. The interface roughness can also lead to a thickness variation of Si3N4 near the interface parallel to the electron beam. As a result, the HRTEM micrographs, taken from the thin specimen regions near the interfaces at a certain defocus value, show the occurrence of an artifact of an ordered structure seemingly different from Si3N4. The present investigations, however, showed that no ordered phase actually different from that of Si3N4 at the interfacial region in Si3N4 could be identified so far. The interfacial structure is likely direct Si3N4/glass bonding, rather than an ordered transition phase between the Si3N4 and the glass phase.
MAS NMR Evidence for the Presence of Silicon in the Alumina Spinel from Thermally Transformed Kaolinite
Authors: MacKenzie Kenneth J. D. , Hartman J. Stephen , Okada Kiyoshi
Published: September 2005

Georgia kaolinite dehydroxylated at 950°C for 24 h, then leached with KOH at 90°C for 1 h, shows a well‐resolved 29Si MAS NMR resonance at −77.5 ppm, within 2 ppm of the calculated position for Si incorporated in γ‐alumina spinel. From a knowledge of the total SiO2 in the leached sample and its partitioning between the spinel and residual grain boundary phases, a maximum of 3.9 wt% is estimated to be present in the spinel.
Preparation of CaF2 Fibers
Authors: Ota Yoshio , Inui Saburo , Iwashita Tetsushi , Kasuga Toshihiro , Abe Yoshihiro
Published: September 2005

Solid and/or hollow CaF2 fibers were prepared from aragonite whiskers. Aragonite (CaCO3) whiskers with diameters of ∼2 μm were converted into CaF2 fibers without deformation by treatment with HF aqueous solution. The resultant CaF2 fibers were polycrystalline with large specific surface areas of ∼60 m2.g−i, and they densified when heated at 800°C. The thickness of the CaF2 reaction layer can be controlled by the concentration of the HF aqueous solution used. Hollow CaF2 fibers were successfully prepared when CaCO3 whiskers covered with CaF2 were leached with HC1.
Meta‐analysis: capsule enteroscopy vs. conventional modalities in diagnosis of small bowel diseases
Authors: MARMO R. , ROTONDANO G. , PISCOPO R. , BIANCO M. A. , CIPOLLETTA L.
Published: September 2005

Background : Prospective trials support the role of capsule enteroscopy as an improvement in diagnosing mucosal lesions in the small bowel.

Aim : To determine the diagnostic yield and safety of capsule enteroscopy vs. alternative diagnostic modalities (such as push enteroscopy, small bowel follow‐through or enteroclysis) in patients with small bowel diseases.

Methods : A search for prospective studies comparing capsule enteroscopy vs. other diagnostic tests in adults was performed between 1966 and 2005. Selected articles were included in a meta‐analysis. Three analyses were run separately, all included studies and studies having occult gastrointestinal bleeding or Crohn's disease as main outcome.

Results : Seventeen studies (526 patients) met inclusion criteria. The rate difference (i.e. the absolute pooled difference in the rate of positive findings) between capsule enteroscopy and alternative modalities for small bowel disease was 41% (95% CI 35.6–45.9); 37% (95% CI 29.6–44.1) for occult gastrointestinal bleeding; and 45% (95% CI 30.9–58.0) for Crohn's disease. Failure to visualize the caecum occurred in 13%, significantly more often in occult bleeders (17%) than in patients with Crohn's disease (8%) (P < 0.006). Adverse events were recorded in 29 patients (6%). Capsule retention was more frequent in patients with Crohn's disease (3% vs. 1%, OR 4.37).

Conclusions : Capsule enteroscopy proved significantly superior to push enteroscopy and small bowel radiology in the diagnosis of ileal diseases. Capsule enteroscopy is safe, though prior radiology is still necessary to rule out small bowel strictures in patients with known or suspected Crohn's disease.
The pharmacokinetic effect of discontinuation of mesalazine on mercaptopurine metabolite levels in inflammatory bowel disease patients
Authors: GILISSEN L. P. L. , BIERAU J. , DERIJKS L. J. J. , BOS L. P. , HOOYMANS P. M. , VAN GENNIP A. , STOCKBRÜGGER R. W. , ENGELS L. G. J. B.
Published: September 2005

Background : In vitro studies suggest interactions between mesalazine (mesalamine) and thiopurines by thiopurine S‐methyltransferase (TPMT) inhibition, influencing the balance of hepatotoxic 6‐methylmercaptopurine ribonucleotide and immunosuppressive tioguanine (thioguanine) metabolites.

Aim : To examine the in vivo pharmacokinetic interaction between mesalazine and mercaptopurine.

Methods : A prospective study was performed in quiescent inflammatory bowel disease patients using the combination of mercaptopurine and mesalazine. Laboratory parameters, 6‐methylmercaptopurine ribonucleotide and tioguanine levels and thiopurine S‐methyltransferase activity in erythrocytes were measured at stable medication, after mesalazine discontinuation and mesalazine reintroduction, further mercaptopurine was continued.

Results : Seventeen patients were participated. Mean mercaptopurine dose was 0.78 mg/kg/day and median of mesalazine dose was 3000 mg/day. After mesalazine discontinuation, mean tioguanine levels changed significantly from 262 to 209 pmol/8 × 108 red blood cell, increasing to 270 after reintroduction. Mean 6‐methylmercaptopurine ribonucleotide levels were 1422, 2149 and 1503 pmol/8 × 108 red blood cell respectively. Mean 6‐methylmercaptopurine ribonucleotide/tioguanine ratio increased significantly from 6.3 at baseline to 11.2. Mean baseline thiopurine S‐methyltransferase activity was 0.58 pmol/106 red blood cell/h and stable. All patients had wild‐type thiopurine S‐methyltransferase genotypes however, leucocyte counts were stable.

Discussion : A significantly higher tioguanine levels and improving 6‐methylmercaptopurine ribonucleotide/tioguanine ratio were found during mesalazine/mercaptopurine combination. Theoretically, mesalazine inhibits thiopurine S‐methyltransferase activity. In vivo thiopurine S‐methyltransferase activity did not change, however.

Conclusion : Mesalazine has synergistic effects on mercaptopurine therapy, but the mechanism is unclear. Combining these drugs may be further indication for mesalazine in inflammatory bowel disease treatment.
Polymorphisms in apoptosis genes predict response to infliximab therapy in luminal and fistulizing Crohn's disease
Authors: HLAVATY T. , PIERIK M. , HENCKAERTS L. , FERRANTE M. , JOOSSENS S. , VAN SCHUERBEEK N. , NOMAN M. , RUTGEERTS P. , VERMEIRE S.
Published: September 2005

Background : Infliximab treatment is effective in 70–80% of patients with refractory luminal and fistulizing Crohn's disease. The effect of infliximab is ascribed to induction of apoptosis.

Aim : To study whether polymorphisms in apoptosis genes predict the response to infliximab and whether they interact with clinical predictors.

Methods : Cohort of 287 consecutive patients treated with infliximab for refractory luminal (n = 204) or fistulizing (n = 83) Crohn's disease was genotyped for 21 polymorphisms in apoptosis genes. Short‐term clinical response was assessed at week 4 (luminal Crohn's disease) or 10 (fistulizing Crohn's disease) after the first infliximab infusion.

Results : The response rate was 69% in luminal and 80% in fistulizing Crohn's disease. In luminal Crohn's disease, two genetic predictors were identified: (i) patients with the Fas ligand −843 CC/CT genotype (n = 135) responded in 75%, with the TT genotype (n = 21) in 38% only (P = 0.002; OR = 0.11; 95% CI: 0.08–0.56). (ii) Patients with the caspase‐9 93 TT (n = 9) genotype all responded, in contrast with 67% (n = 147) with the CC and CT genotype (P = 0.04; OR = 1.50; 95% CI: 1.34–1.68). Concomitant azathioprine/mercaptopurine therapy overcame the effect of unfavourable genotypes. In the fistulizing Crohn's disease cohort, the same Fas ligand −843 CC/CT genotype was the only predictor of response (P = 0.002; OR = 1.66; 95% CI: 1.21–2.29), interacting with caspase‐9 93 polymorphism but not with azathioprine/mercaptopurine.

Conclusion : We observed that polymorphisms in FasL/Fas system and caspase‐9 influence the response to infliximab in luminal and fistulizing Crohn's disease. The strongest association was seen between the Fas ligand −843 TT genotype and non‐response. Concomitant mercaptopurine/azathioprine therapy, however, was able to overcome the effect of unfavourable genotypes in luminal disease.
Treatment of patients with heartburn without endoscopic evaluation: on‐demand treatment after effective continuous administration of lansoprazole 15 mg
Authors: BIGARD M. A. , GENESTIN E.
Published: September 2005

Background : Relapse is frequent after initial treatment for gastro‐oesophageal reflux. An alternative strategy to intermittent or continuous therapy may be on‐demand treatment.

Aim : To compare the efficacy and safety of on‐demand lansoprazole 15 mg and placebo treatment in patients with gastro‐oesophageal reflux.

Methods : This was a multicentre, randomized, double‐blind study in two parallel groups of patients. In the acute study phase, all included patients (n = 203) were treated with lansoprazole 15 mg (once per day) for 4 weeks. At week 4, asymptomatic patients entered the 6‐month, on‐demand, follow‐up phase and were randomized to receive either lansoprazole 15 mg (once per day) or placebo.

Results : A higher percentage of patients in the lansoprazole group completed the 6‐month follow‐up than in the placebo group [81% vs. 61% (P = 0.003)]. Only 16% of patients in the lansoprazole group discontinued the study for insufficient control of heartburn vs. 28% in the placebo group (P = 0.046). The mean daily intake in patients who completed the study was 1–5 capsules/day in the lansoprazole 15 mg group.

Conclusions : On‐demand treatment with lansoprazole 15 mg in symptomatic patients after short‐term, continuous treatment is a promising therapeutic alternative to intermittent and continuous treatment to maintain heartburn control in patients with gastro‐oesophageal reflux.
The association between admission for poisoning with paracetamol or other weak analgesics and subsequent admission for psychiatric disorder: a Danish nationwide case–control study
Authors: JEPSEN P. , QIN P. , NØRGÅRD B. , AGERBO E. , MORTENSEN P. B. , VILSTRUP H. , SØRENSEN H. T.
Published: September 2005

Background : Many cases of paracetamol poisoning are with suicidal intent, but the association between paracetamol poisoning and subsequent psychiatric disorder is unknown.

Aim : To examine the association between poisoning with paracetamol or other weak analgesics and subsequent psychiatric disorder.

Methods : The study was set in a nested case–control design and based on nationwide Danish registers. We identified all patients diagnosed with schizophrenia, affective disorder or eating disorder in 1994–1998 and matched population controls. We estimated the relative risk of these psychiatric disorders after admission for paracetamol or nonparacetamol poisoning, adjusting for income, employment and marital status.

Results : We included 12 603 cases with psychiatric disorder, and 1.2% had a diagnosis of poisoning compared with 0.2% of the 252 060 matched population controls. Compared with those with no diagnoses of weak analgesic poisoning, the risk of schizophrenia increased 3.9‐fold after paracetamol poisoning, and 2.0‐fold after nonparacetamol poisoning. The risk of affective disorder increased 12.2‐fold after paracetamol poisoning and 2.6‐fold after nonparacetamol poisoning. The risk of eating disorder increased 5.0‐fold after paracetamol poisoning, and 2.2‐fold after nonparacetamol poisoning. The risk of a diagnosis of psychiatric disorder was very high immediately after poisoning and remained increased for more than 10 years.

Conclusions : Paracetamol poisoning is a strong risk marker for psychiatric disorder, particularly affective disorders.
Haematopoietic stem cell transplantation for Shwachman–Diamond disease: a study from the European Group for blood and marrow transplantation
Authors: Cesaro Simone , Oneto Rosi , Messina Chiara , Gibson Brenda E. , Buzyn Agnes , Steward Colin , Gluckman Eliane , Breddius Robbert , Boogaerts Marc , Vermylen Christiane , Veys Paul , Marsh Judith , Badell Isabel , Michel Gerard , Güngör Tayfun , Niethammer Dietrich , Bordigoni Pierre , Oswald Cecilia , Favre Claudio , Passweg Jakob , Dini Giorgio ,   the EBMT Severe Aplastic Anaemia and Paediatric Diseases Working Party
Published: September 2005

This report assessed the results of allogeneic stem cell transplantation (allo‐SCT) in 26 patients with Shwachman–Diamond disease (SDS) and severe bone marrow abnormalities. The conditioning regimen was based on busulphan (54%), total body irradiation (23%), fludarabine (15%) or other chemotherapy combinations (8%). Standard prevention of graft versus host disease (GVHD) with ciclosporin ± methotrexate was adopted in 54% of the patients whilst in vivo or in vitro T‐cell depletion was used in 17 and four patients respectively. Neutrophil and platelet engraftment were achieved in 21 (81%) and 17 (65%) of 26 patients after a median time of 18 days and 29 days respectively. The incidence of grade III and IV acute GVHD was 24% and of chronic GVHD 29%. Nine patients died after a median time of 70 d, post‐SCT. After a median follow‐up of 1·1 years, the transplant‐related mortality was 35·5% (95% CI 17–54) whilst the overall survival was 64·5% (95% CI 45·7–83·2). Allo‐SCT was found to be successful in more than half of SDS patients with severe bone marrow dysfunction. Further improvements would be anticipated by a better definition of the optimum time in the course of disease to transplant and by the adoption of less toxic conditioning regimens.
Epidemiology and outcome of infections due to Aspergillus terreus: 10‐year single centre experience
Authors: Lass‐Flörl Cornelia , Griff Katharina , Mayr Astrid , Petzer Andreas , Gastl Günter , Bonatti Hugo , Freund Martin , Kropshofer Gabriele , Dierich Manfred P. , Nachbaur David
Published: September 2005

Aspergillus terreus, a less common pathogen, appears to be an emerging cause of infection at our institution, the Medical University Hospital of Innsbruck. Thus the epidemiology and outcome of A. terreus infections over the past 10 years was assessed. We analysed 67 cases of proven invasive aspergillosis (IA) according to the European Organisation for Research and Treatment of Cancer/Mycoses Study Group criteria, investigated antifungal susceptibility of amphotericin B (AMB), voriconazole and caspofungin and performed molecular typing of A. terreus. Patients with proven IA caused by A. terreus (n = 32) and non‐A. terreus (n = 35) were evaluated. The two groups were comparable in terms of age, gender, underlying disease, antifungal prophylaxis and duration of neutropenia (P > 0·05). Leukaemia was the most common underlying malignancy. Fungal dissemination occurred in 63% of the patients. Aspergillus terreus infections were associated with a lower response rate to AMB therapy (20%), compared with 47% for patients with non‐A. terreus infections (P < 0·05). In vitro, A. terreus was found to be resistant to AMB and molecular typing discriminated between patients isolates, showing a high strain diversity with 26 distinct types (I‐XXVI) identified by combination of three primers. Aspergillus terreus infections displayed evidence of AMB resistance in vitro and in vivo and were associated with a high rate of dissemination and poor outcome; A. terreus causes systemic infections of endemic character in Tyrol, Austria. The onset of A. terreus infection depends not on the degree of immunosuppression but on environmental Aspergillus spp. exposure.
A comparison of computerised strain gauge plethysmography with D‐dimer testing in screening for deep‐vein thrombosis
Authors: Williams D. , Lee A. J. , Clark H. , Webster J. , Watson H. G.
Published: September 2005

There has been a significant increase in the amount of diagnostic testing performed to confirm or refute a diagnosis of deep‐vein thrombosis (DVT), often in low‐risk patients. d‐dimer testing and computer‐assisted strain gauge plethysmography (SGP) are rapid, inexpensive methods of excluding DVT and, in combination with a clinical probability score for DVT, both have been used to accurately exclude DVT. d‐dimer testing, SGP and a combination of both in excluding DVT were compared in 243 ambulant outpatients who followed a prespecified investigation protocol. The negative‐predictive value of d‐dimer testing alone was 100%, 93·9% (95% CI 93·6–94·1) and 80% (95% CI 73·7–86·3) in patients with a low, moderate and high pretest probability (PTP) score for DVT respectively. The corresponding results for SGP were 95·6% (95% CI 95·5–95·7), 86·1% (95% CI 85·9–86·4) and 77·8% (95% CI 75·9–79·7) in patients with a low, moderate and high PTP score for DVT respectively. d‐dimer testing provided a rapid, cost‐effective method for excluding DVT in low‐risk ambulant patients, which was superior to SGP. Combined use of the modalities did not improve any aspect of clinical decision making.
Ontogenetic shifts in the functional response and interference interactions ofRhyacophila dorsalislarvae (Trichoptera)
Authors: ELLIOTT J. M.
Published: September 2005

1. Ontogenetic shifts in predator behaviour can affect the assessment of food‐web structure and the development of predator–prey models. Therefore, it is important to establish if the functional response and interference interactions differ between life‐stages. These hypotheses were tested by (i) comparing the functional response of second, third, fourth and fifth larval instars ofRhyacophila dorsalis, using three stream tanks with oneRhyacophilalarva per tank and one of 10 prey densities between 20 and 200 larvae ofChironomussp.; (ii) using other experiments to assess interference within instars (two to five larvae of the same instar per tank), and between pairs of different instars (one, two or three larvae per instar; total predator densities of two, four or six larvae per tank).

2. The first hypothesis was supported. The number of prey eaten by each instar increased with prey density, the relationship being described by a type II model. The curvilinear response was stronger for fourth and fifth instars than for second and third instars. Mean handling time did not change significantly with prey density, and increased with decreasing instar number from 169 s for fifth instars to 200 s for second instars. Attack rate decreased progressively with decreasing instar number. Handling time varied considerably for each predator–prey encounter, but was normally distributed for each predator instar. Variations in attack rate and handling time were related to differences in activity between instars, fourth and fifth instars being more active and aggressive than second and third instars, and having a higher food intake.

3. The second hypothesis was partially supported. In the interference experiments between larvae of the same instar or different instars, mean handling time did not change significantly with increasing predator density, and attack rate did not change for second and third instars but decreased curvilinearly for fourth and fifth instars. Interference between some instars could not be studied because insufficient second instars were available at the same time as fourth and fifth instars, and most third instars were eaten by fourth and fifth instars in the experiments. Prey capture always decreased with decreasing attack rate. Therefore, interference reduced prey consumption in fourth and fifth instars, but not in second and third instars. The varying feeding responses of different instars should be taken into account when assessing their role in predator–prey relationships in the field.
Increased growth and recruitment of piscivorous perch, Perca fluviatilis, during a transient phase of expanding submerged vegetation in a shallow lake
Authors: HARGEBY ANDERS , BLOM HENRIK , BLINDOW IRMGARD , ANDERSSON GUNNAR
Published: September 2005

1. In this study, we examine how a 7‐year period of expanding submerged stonewort (Chara spp.) vegetation during a shift from turbid to clear water in a shallow lake influenced individual growth and population size structure of perch (Perca fluviatilis). We expected that a shift from phytoplankton to macrophyte dominance and clear water would improve feeding conditions for perch during a critical benthivorous ontogenetic stage, and enhance the recruitment of piscivorous perch.

2. Growth analysis based on opercula showed that growth during the second year of life was significantly higher in years with abundant vegetation than in years with turbid water and sparse vegetation. Growth was not affected during the first, third and fourth year of life. Stable isotope analyses on opercula from 2‐year‐old perch showed that the increase in growth coincided with a change in carbon source in the diet. Stable nitrogen ratio did not change, indicating that the increased growth was not an effect of any change in trophic position.

3. Following the expansion of submerged vegetation, perch size range and abundance of piscivorous perch increased in central, unvegetated areas of the lake. In stands of stoneworts, however, mainly benthivorous perch were caught, and size range did not change with time.

4. Our findings provide empirical support for the notion that establishment of submerged vegetation may lead to increased recruitment of piscivorous perch, because of improved competitive conditions for perch during the benthivorous stage. This is likely to constitute a benthic‐pelagic feedback coupling, in which submerged vegetation and clear water promote the recruitment of piscivorous perch, which, in turn, may increase water clarity through top‐down effects in the pelagic.
Effects of cold‐girdling on flows in the transport phloem in Ricinus communis: is mass flow inhibited?
Authors: PEUKE ANDREAS D. , WINDT CAREL , VAN AS HENK
Published: September 2005

The effects of cold girdling of the transport phloem at the hypocotyl of Ricinus communis on solute and water transport were investigated. Effects on the chemical composition of saps of phloem and xylem as well as of stem tissue were studied by conventional techniques and the water flow in the phloem was investigated by NMR imaging. Cold girdling reduced the concentration of sucrose but not that of inorganic solutes or amino acids in phloem saps. The possibility that cold treatment inhibited the retrieval of sucrose into the phloem, following leaching from the sieve tubes along a chemical gradient is discussed. Leaching of other solutes did not occur, as a result of missing promoting gradients in stem tissue. Following 3 d of cold girdling, sugar concentration increased and starch was synthesized and accumulated in stem tissue above the cold girdling region and along the cold‐treated phloem pathway due to leaching of sugars from the phloem. Only in the very first period of cold girdling (< 15–30 min) was mass flow inhibited, but recovered in the rest of cold treatment period to values similar to the control period before and the recovery period after the cold treatment. It is concluded that cold treatment affected phloem transport through two independent and reversible processes: (1) a permanent leaching of sucrose from the phloem stem without normal retrieval during cold treatment, and (2) a short‐term inhibition of mass flow at the beginning of cold treatment, possibly involving P proteins. Possible further mechanisms for reversible inhibition of water flow are discussed.
Contributions of evaporation, isotopic non‐steady state transpiration and atmospheric mixing on the δ18O of water vapour in Pacific Northwest coniferous forests
Authors: LAI CHUN‐TA , EHLERINGER JAMES R. , BOND BARBARA J. , PAW U KYAW THA
Published: September 2005

Changes in the 2H and 18O of atmospheric water vapour provide information for integrating aspects of gas exchange within forest canopies. In this study, we show that diurnal fluctuations in the oxygen isotope ratio (δ18O) as high as 4‰ were observed for water vapour (δ18Ovp) above and within an old‐growth coniferous forest in the Pacific Northwest region of the United States. Values of δ18Ovp decreased in the morning, reached a minimum at midday, and recovered to early‐morning values in the late afternoon, creating a nearly symmetrical diurnal pattern for two consecutive summer days. A mass balance budget was derived and assessed for the 18O of canopy water vapour over a 2‐d period by considering the 18O‐isoflux of canopy transpiration, soil evaporation and the air entering the canopy column. The budget was used to address two questions: (1) do δ18O values of canopy water vapour reflect the biospheric influence, or are such signals swamped by atmospheric mixing? and (2) what mechanisms drive temporal variations of δ18Ovp? Model calculations show that the entry of air into the canopy column resulted in an isotopically depleted 18O‐isoflux in the morning of day 1, causing values of δ18Ovp to decrease. An isotopically enriched 18O‐isoflux resulting from transpiration then offset this decreased δ18Ovp later during the day. Contributions of 18O‐isoflux from soil evaporation were relatively small on day 1 but were more significant on day 2, despite the small H216O fluxes. From measurements of leaf water volume and sapflux, we determined the turnover time of leaf water in the needles of Douglas‐fir trees as ≈ 11 h at midday. Such an extended turnover time suggests that transpiration may not have occurred at the commonly assumed isotopic steady state. We tested a non‐steady state model for predicting δ18O of leaf water. Our model calculations show that assuming isotopic steady state increased isoflux of transpiration. The impact of this increase on the modelled δ 18Ovp was clearly detectable, suggesting the importance of considering isotopic non‐steady state of transpiration in studies of forest 18O water balance.
Identification of QTL controlling root growth response to phosphate starvation in Arabidopsis thaliana
Authors: REYMOND MATTHIEU , SVISTOONOFF SERGIO , LOUDET OLIVIER , NUSSAUME LAURENT , DESNOS THIERRY
Published: September 2005

One of the responses of plants to low sources of external phosphorus (P) is to modify root architecture. In Arabidopsis thaliana plantlets grown on low P, the primary root length (PRL) is reduced whereas lateral root growth is promoted. By using the Bay‐0 × Shahdara recombinant inbred line (RIL) population, we have mapped three quantitative trait loci (QTL) involved in the root growth response to low P. The Shahdara alleles at these three QTL promote the response of the primary root to low P (i.e. root length reduction). One of these QTL, LPR1, located in a 2.8 Mb region at the top of chromosome 1, explains 52% of the variance of the PRL. We also detected a single QTL associated with primary root cell elongation in response to low P which colocalizes with LPR1. LPR1 does not seem to be involved in other typical P‐starvation responses such as growth and density of root hairs, excretion of acid phosphatases, anthocyanin accumulation or the transcriptional induction of the P transporter Pht1;4. LPR1 might highlight new aspects of root growth that are revealed specifically under low P conditions.
Internal conductance does not scale with photosynthetic capacity: implications for carbon isotope discrimination and the economics of water and nitrogen use in photosynthesis
Authors: WARREN CHARLES R. , ADAMS MARK A.
Published: September 2005

Central paradigms of ecophysiology are that there are recognizable and even explicit and predictable patterns among species, genera, and life forms in the economics of water and nitrogen use in photosynthesis and in carbon isotope discrimination (Δ). However most previous examinations have implicitly assumed an infinite internal conductance (gi) and/or that internal conductance scales with the biochemical capacity for photosynthesis. Examination of published data for 54 species and a detailed examination for three well‐characterized species –Eucalyptus globulus, Pseudotsuga menziesii and Phaseolus vulgaris– show these assumptions to be incorrect. The reduction in concentration of CO2 between the substomatal cavity (Ci) and the site of carbon fixation (Cc) varies greatly among species. Photosynthesis does not scale perfectly with gi and there is a general trend for plants with low gi to have a larger draw‐down from Ci to Cc, further confounding efforts to scale photosynthesis and other attributes with gi. Variation in the gi–photosynthesis relationship contributes to variation in photosynthetic ‘use’ efficiency of N (PNUE) and water (WUE). Δ is an information‐rich signal, but for many species only about two‐thirds of this information relates to A/gs with the remaining one‐third related to A/gi. Using data for three well‐studied species we demonstrate that at common WUE, Δ may vary by up to 3‰. This is as large or larger than is commonly reported in many interspecific comparisons of Δ, and adds to previous warnings about simplistic interpretations of WUE based on Δ. A priority for future research should be elucidation of relationships between gi and gs and how these vary in response to environmental conditions (e.g. soil water, leaf‐to‐air vapour pressure deficit, temperature) and among species.
Ecological physiology of Pereskia guamacho, a cactus with leaves
Authors: EDWARDS ERIKA J. , DIAZ MIRIAM
Published: September 2005

The specialized physiology of leafless, stem‐succulent cacti is relatively well understood. This is not true, however, for Pereskia (Cactaceae), the 17 species of leafy trees and shrubs that represent the earliest diverging lineages of the cacti. Here we report on the water relations and photosynthesis of Pereskia guamacho, a small tree of the semiarid scrubland of Venezuela's Caribbean coast. Sapwood‐specific xylem conductivity (Ksp) is low when compared to other vessel‐bearing trees of tropical dry systems, but leaf‐specific xylem conductivity is relatively high due to the high Huber value afforded by P. guamacho's short shoot architecture. P. guamacho xylem is not particularly vulnerable to drought‐induced cavitation, especially considering the high leaf water potentials maintained year round. This is confirmed by the lack of significant variation exhibited in Ksp between wet and dry seasons. In the rainy season, P. guamacho exhibited C3‐like patterns of stomatal conductance, but during a prolonged drought we documented nocturnal stomatal opening with a concomitant accumulation of titratable acid in leaves. This suggests that P. guamacho can perform drought‐induced crassulacean acid metabolism (CAM photosynthesis), although δ13C values imply that most carbon is assimilated via the C3 pathway. P. guamacho leaves display very low stomatal densities, and maximum stomatal conductance is low whether stomata open during the day or night. We conclude that leaf performance is not limited by stem hydraulic capacity in this species, and that water use is conservative and tightly regulated at the leaf level.
Adaptive speciation when assortative mating is based on female preference for male marker traits
Authors: DOEBELI M.
Published: September 2005

Adaptive speciation occurs when frequency‐dependent ecological interactions generate conditions of disruptive selection to which lineage splitting is an adaptive response. Under such selective conditions, evolution of assortative mating mechanisms enables the break‐up of the ancestral lineage into diverging and reproductively isolated descendent species. Extending previous studies, I investigate models of adaptive speciation due to the evolution of indirect assortative mating that is based on three different mating traits: the degree of assortativity, a female preference trait and a male marker trait. For speciation to occur, linkage disequilibria between different mating traits, e.g. between female preference and male marker traits, as well as between mating traits and the ecological trait, must evolve. This can lead to novel speciation scenarios, e.g. when reproductive isolation is generated by a splitting in the degree of assortativeness, with one of the emerging lineages mating assortatively, and the other one disassortatively. I investigate the effects of variation in various model parameters on the likelihood of speciation, as well as robustness of speciation to introducing costs of assortative mating. Even though in the models presented speciation requires the genetic potential for strong assortment as well as rather restrictive ecological conditions, the results show that adaptive speciation due to the evolution of assortative mating when mate choice is based on separate female preference and male marker traits is a theoretically plausible evolutionary scenario.
Are hybridogenetic complexes structured by habitat in water frogs?
Authors: PLENET S. , JOLY P. , HERVANT F. , FROMONT E. , GROLET O.
Published: September 2005

The success and the evolutionary fate of hybridogenetic lineages are explained by both a generalistic heterosis hypothesis and an alternative hypothesis, the habitat segregation hypothesis. Because such hypotheses have rarely been tested at the level of whole habitats, our aim was to compare performances of two taxa within a hybridogenetic complex across diverse natural habitats. We took advantage of the waterfrog hybridogenetic complex (Rana esculenta and R. lessonae) by rearing tadpoles in natural contrasted habitats by means of enclosure experiments. We also monitored the frequency of each taxon in the waterfrog assemblages that naturally breed in the studied ponds. The hybridogenenetic taxon showed no evidence of broader tolerance as growth, development and physiology strongly varied in response to environmental heterogeneity. Our study reveals a differential success of the hybridogenetic taxon and its sexual host among environments. Moreover, hybridogenetic taxa rarely dominated the sexual species in natural assemblages. Consequently, our results show that the generalistic model does not explain the success of hybridogenetic lineages, but rather support the habitat segregation, among other alternative concepts.
Disjunct distributions during glacial and interglacial periods in mountain butterflies: Erebia epiphron as an example
Authors: Schmitt T. , Hewitt G. M. , Müller P.
Published: September 2005

Over several decades, the distribution patterns and evolution of alpine disjunct species has become an increasingly discussed subject. Large scale genetic analysis has allowed the resolution of the past range changes and intraspecific evolution of many species, in Europe especially of Mediterranean origin. However, the phylogeographic structures of species with arctic–alpine disjunct distribution patterns are relatively poorly studied. The existing phylogeographic analysis (mostly of alpine plant species) supports disjunct distributions during glacial as well as post-glacial periods for a number of species. However, several questions still remain unresolved and we therefore analysed the Mountain Ringlet Erebia epiphron as a model for such alpine disjunct species. We found strong differentiation into five different lineages supporting five differentiation centres: (i) the eastern Pyrenees, (ii) the mountain ranges between the central Pyrenees and south-western Alps, (iii, iv) two areas along the southern Alps margin and (v) the northern Alps margin. We propose that these patterns evolved due to the humidity requirements of this species, which did not allow survival in the dry glacial steppes, but along the margins of the wetter glaciated high mountain ranges.
Timing and tempo of primate speciation
Authors: Curnoe D. , Thorne A. , Coate J. A.
Published: September 2005

Published molecular clocks for primates are used to estimate typical divergence times for phylogroups (1.6 Ma), species (3.3 Ma), sister species (2.7 Ma), genera (8.9 Ma) and sister genera (8.6 Ma). Significant median differences exist between major groups (infraorders and superfamilies) for various divergence times. These data are employed to estimate typical maximum duration of speciation. Typical primate values (1.1 Ma) suggest this process to be faster than is characteristic of many vertebrates. However, after considering divergence times for hybridizing congeneric and confamilial primates, this value is likely only to estimate the commencement of prezygotic isolating mechanisms, rather than the completion of reproductive isolation. Thus, speciation typically takes around 1.0 Ma to more than 4.0 Ma to occur, depending on whether prezygotic or post-zygotic isolating mechanisms are emphasized. Typical primate genus age is around 5.3 Ma, but we note differences among major groups. In light of these estimates, the classification of humans and chimpanzees is reconsidered using a molecular yardstick approach. Three taxonomic frameworks may flow from molecular analyses, all of them having major implications for understanding the evolution of humans and chimpanzees.
Size asymmetry in intraspecific competition and the density-dependence of inbreeding depression in a natural plant population: a case study in cassava (Manihot esculenta Crantz, Euphorbiaceae)
Authors: Pujol B. , Mckey D.
Published: September 2005

The effects of competition on the genetic composition of natural populations are not well understood. We combined demography and molecular genetics to study how intraspecific competition affects microevolution in cohorts of volunteer plants of cassava (Manihot esculenta) originating from seeds in slash-and-burn fields of Palikur Amerindians in French Guiana. In this clonally propagated crop, genotypic diversity is enhanced by the incorporation of volunteer plants into farmers’ stocks of clonal propagules. Mortality of volunteer plants was density-dependent. Furthermore, the size asymmetry of intraspecific competition increased with local clustering of plants. Size of plants was correlated with their multilocus heterozygosity, and stronger size-dependence of survival in clusters of plants, compared with solitary plants, increased the magnitude of inbreeding depression when competition was severe. The density-dependence of inbreeding depression of volunteer plants helps explain the high heterozygosity of volunteers that survive to harvest time and thus become candidates for clonal propagation. This effect could help favour the maintenance of sex in this ‘vegetatively’ propagated crop plant.
A quantitative trait locus for recognition of foreign eggs in the host of a brood parasite
Authors: Martín-Gálvez D. , Soler J. J. , Martínez J. G. , Krupa A. P. , Richard M. , Soler M. , Møller A. P. , Burke T.
Published: September 2005

Avian brood parasites reduce the reproductive output of their hosts and thereby select for defence mechanisms such as ejection of parasitic eggs. Such defence mechanisms simultaneously select for counter-defences in brood parasites, causing a coevolutionary arms race. Although coevolutionary models assume that defences and counter-defences are genetically influenced, this has never been demonstrated for brood parasites. Here, we give strong evidence for genetic differences between ejector and nonejectors, which could allow the study of such host defence at the genetic level, as well as studies of maintenance of genetic variation in defences. Briefly, we found that magpies, that are the main host of the great spotted cuckoo in Europe, have alleles of one microsatellite locus (Ase64) that segregate between accepters and rejecters of experimental parasitic eggs. Furthermore, differences in ejection rate among host populations exploited by the brood parasite covaried significantly with the genetic distance for this locus.
Genotype × environment interaction for male attractiveness in an acoustic moth: evidence for plasticity and canalization
Authors: Danielson-François A. M. , Kelly J. K. , Greenfield M. D.
Published: September 2005

The lek paradox arises when choosy females deplete the genetic variance for male display traits from a population, yet substantial additive genetic variation (VA) in male traits persists. Thus, the lek paradox can be more generally stated as one of the most fundamental evolutionary questions: What maintains genetic variation in natural populations? One solution to this problem may be found in the condition-dependent nature of many sexually selected traits. Genotype × environment (G × E) interactions can maintain VA under conditions of environmental heterogeneity provided certain restrictions are met, although antagonistic pleiotropy has also been proposed as a mechanism. Here, we provide evidence for G × E interactions and against the role of antagonistic pleiotropy in the maintenance of VA for sexually selected traits. Using inbred lines of the lesser waxmoth Achroia grisella, we measured VA for song attractiveness, condition and development rate under different competitive environments and found that genotypes differed in their plasticity. We argue that variation persists in natural populations because G × E interactions prevent any one variant from producing the optimal phenotype across all environments.
Mineral chemistry of spinel peridotite xenoliths from Baengnyeong Island, South Korea, and its implications for the paleogeotherm of the uppermost mantle
Authors: Choi Sung Hi , Kwon Sung‐Tack
Published: September 2005

Abstract  The mantle‐derived xenoliths entrained in the Pliocene basanite from Baengnyeong Island, South Korea, are spinel lherzolites and spinel harzburgites. The overall compositional range of the Baengnyeong xenoliths matches that of the post‐Archean xenoliths of lithospheric mantle origin from eastern China, but without any compositional evidence for a refractory Archean mantle root. Mineral compositions of the xenoliths have been used to estimate the equilibrium temperatures and pressures, and to construct a paleogeothermal gradient of the source region. The xenolith‐derived paleogeotherm is constrained from about 820°C at 7.3 kbar to 1000°C at 20.6 kbar. Like those from the post‐Archean Chinese xenoliths of lithospheric mantle origin, the Baengnyeong geotherm is considerably elevated relative to the conductive models at the depth of the crust–mantle boundary, reflecting a thermal perturbation probably related to lithospheric thinning. There is no significant P/T difference between harzburgite and lherzolite, which suggests that the harzburgites are interlayered with lherzolites within the depth interval beneath Baengnyeong Island.